>>> 4sep02 #9154-11297 +++ #9586 From: Del Rawlins Subject: Mods. Was Re: Hello Everyone >There are a couple of modifications that I would be interested in >making, building the cabin/cockpit area a little wider and deeper and >building the aeroplane so that it can be quickly converted between >tri-gear and tailwheel. There are a whole lot of reasons for the >undercarriage idea. Bob Barrows has mentioned the possibility of widening the cockpit by up to a couple of inches to other builders in the past. You should ask him about that and the other mods when you call/write him to order your plans. He is fairly open to discussing modifications with builders, although based on what I've seen on the list I wouldn't expect him to get really excited about a trigear Bearhawk. As far as making the fuselage deeper, it has been reported here that people well over 6 feet tall don't have any problems fitting into the Bearhawk as designed, if that is what you are getting at. If you are really serious about tricycle gear, we have a member of this list who is building a Christavia Mark IV as a nosedragger (his plans show conventional gear). Since the two aircraft are very similar maybe he will be able to fill you in on the changes he has made. +++ #9588 From: "Bruce A. Frank" Subject: Mods Making a wider cabin is pretty straight forward with no modification to the basic structure, at least for the pilot and front passenger. One can keep the leading edge of the door in the same position, but make a minor repositioning of the trailing edge. All that is required is to add a tube outboard of the structural tube that is normally the trailing edge of the door frame. The cargo door and side windows may need the frames extended outward slight and fabric forming stringers may need to be slightly repositioned to maintain the lines and to smooth transition, but still more a cosmetic rework. The structural tubes of the fuselage do not have to be reworked. This change puts the width right where two guys my size (6'4", 280lbs) usually have to overlap shoulders. I have made this change to my TriPacer fuselage giving me 44" of cabin width across the front seats. +++ #9610 From: Del Rawlins Subject: Re: Mods > Making a wider cabin is pretty straight forward with no modification > to the basic structure, I don't think anybody else has mentioned it so far, but the design of the Bearhawk makes widening the doors easier than this. The door width is already determined by .032 4130 sheet welded to the structural tube, so that changing the width would require nothing more than changing the size/shape of the sheet. As you mentioned there may be complications with the windows and cargo doors, but otherwise it should just be a matter of positioning the fairing strips to fit the new door profile. Course as skinny as I am I don't forsee myself making those modifications... +++ #9621 From: "Bruce A. Frank" Subject: Re: Mods I agree. My Piper fuselage actually had a similar door frame design. I had removed that structure and added tube with tabs for screws to allow the sheet metal to be replaceable. I did this to eliminate the inaccessible under-areas that were originally welded and prone to rust. I had forgotten that the Bearhawk follows similar construction designs used by Piper, but I don't know specifically what the door structure on the Bearhawk looks like. My suggestion and method explanation is intended to insert the idea into the process, not to give cookbook directions. There were no such directions given for the V-6 STOL either. Heck, Blanton wouldn't provide any input to making the pilot side door. His statement was, "just make it like the passenger side door," which actually was enough. +++ #9805 From: "Shannon" shanspur@w... Subject: RE: Design Compromises How about using something like Kent Paser's "Speed With Economy" to make fairings, seals, etc. to clean up the 'Hawk? That's my intention WHEN able to begin construction. Also, how much extra speed is needed to significantly reduce travel time over 1,000 miles? Unless you double your speed, it's hard to justify the expense and fuel consumption of a Lancair IV-P, which I couldn't afford to keep airborne, let alone build. That's why I like the Bearhawk. Reasonable speed, reasonable room, great utility, at reasonable cost. Plus, you get to build it yourself! Just my totally unprejudiced, completely reasoned opinion. +++ #10016 From: "rodsmith52" "Rod Smith" Subject: Re: fitting in Since the Bearhawk doesn't have jury struts, its going to be difficult to mount a rifle at the strut interesection which is standard equipment on an Alaskan Supercub. Maybe I'll add a non structural jury strut on one wing for that purpose :^) +++ #10018 From: "Bruce A. Frank" Subject: Re: Re: fitting in Maybe a scabbard strapped to the single strut! 8^) +++ #11045 From: "Shawn Harrison" Subject: Re: Erbman's Silly Responses > My idea was instead of leaving lift points out in the airstream > constantly causing drag, I would create some devices that would fit > under the front and rear spar attach points and attach to the lifting > device. You'd have to remove the fairing between the wing and > fuselage to install them. Any reason not to use a "push up" device (i.e., a jack) instead of a "lift up" device? Jack it up by pushing on the gear legs, no? +++ #11048 From: Russ and Penny Erb Subject: RE: Erbman's Silly Responses > Any reason not to use a "push up" device (i.e., a jack) instead of a > "lift up" device? Jack it up by pushing on the gear legs, no? Because the point of the exercise is to remove the wheels and put on floats (or the other way round). A jack would be very much in the way. Additionally, bump an airplane on jacks and it tends to fall over, accompanied by very expensive noises. Bump a hanging airplane and it swings. Also, the crane may be used to lift the airplane over the dock and lower it into the water. +++ #11049 From: Del Rawlins Subject: Re: Erbman's Silly Responses > My idea was instead of leaving lift points out in the airstream > constantly causing drag, I would create some devices that would fit > under the front and rear spar attach points and attach to the lifting > device. You'd have to remove the fairing between the wing and > fuselage to install them. The lift points on Boog's Cub consist of some extruded aluminum angles that are bolted through with the spar attach bolts. Above where they bolt on, one half of the angle is ground away, so that all that protrudes through the fairing is about 1/8 thick aluminum maybe 1" to 1-1/2" high. I wonder if it would even be possible to measure the difference in drag. Any cruise speed increase and subsequent time savings would probably be eliminated by the need to remove the fairings and install the other lift points at least twice each year. +++ #11050 From: Russ and Penny Erb Subject: RE: Erbman's Silly Responses > The lift points on Boog's Cub consist of some extruded aluminum angles > that are bolted through with the spar attach bolts. Interesting. The only example I've seen of lift points was on a Cessna 180. They looked like 4 eye bolts sticking out of the top of the wing serving no purpose other than as drag producing devices. Boog's system sound much less draggy. Then again, my suggestion was made based on how I would approach it, figureing the requirement to lift the airplane would happen very few times if ever. I see your point about if it needs to be done on a regular basis. +++ #11057 From: Ken Beanlands Subject: Re: Erbman's Silly Responses If you are flying on floats, especially in the bush, you better make sure you have those liftpoints on all the time. It's added insurance (like the safety wires on a PA-18 landing Gear). Growing up around floatplanes you learn quickly that there are a number of things that can go wrong very quickly and having the ability to get a crane or hoist on the airplane quickly to save it. So far, I've been involved with 3 such situations. 1 was while trying to recover an airplane after it sunk. Being able to snag the eye-rings without having to deal with root fairings , etc. underwater was a real help. Another occassion was a 180 that sank the outside float while tied to a dock. We were able to get a crane on it quick enoug to avoid any water or major structural damage. If we had needed to fool with root fairings while the airplane was banked over 30 degrees and in 50 kts winds, we probably would have lost the plane. The third plane sunk to her belly after a heavy, wet, early season snow storm. We went out to check on our 180 to find the decks about 1"-2" above the water rather than the normal 6"-8" We were able to reach the wings with a push broom and clear off the snow load and she popped back up. THe c-172 tied up at the next dock did not fair so well. It had the same snow load, but much smaller floats. We were able to get a crane out and lift the plane off the bottom far enough to get some planks under her to prevent the floats from being damaged in the high winds. For the minor amount of drag they cause, do yourselves a favour and stick them in permanently. One other point, Never lift an airplane out of the water when the floats are full. A 180 can have as much as 3 tons of water in the floats which could be enough to damage attach fittings. BTW, I had the unfortunate experience of seeing a C-180 crash to the floor while switching from floats to wheels one fall. The owners had recently traded the 172 in on a 180 and this was the first swap. They tied into the same main roof beam that had been used on the 172, hoisted the plain, removed the floats and installed the tailwheel when the beam let go. Fortunately, snow had drifted in through the open door the night before and the floats had already been slid out of the way. There was also someone standing near the wingtip. Just before the plane hit the ground, the beam hit the lower stringer of teh roof rafter and went through absorbing some of the impact foce and slowing the fall. I was amazed that the 2 little steps on either side of the plane were strong enough to prevent the belly from being damaged! The end result was having to replace the steps, straiten out a dent in the exhaust stack and fix 2 or three dents and scratched in the cabin roof where the roof debris fell. It didn't even damage the antenae on the belly! It was in the air a week later. +++ #11058 From: "Matt" mprather@s... Subject: Re: Erbman's Silly Responses How about a compromise? Maybe design some ears permanantly onto the front and rear spars that have threaded holes in them to accept lifting eyes. Keep the lifting eyes in a little bag in the airplane. Use inspection covers over the holes in the skin that allow access to the tabs mounted to the spars. Or alternately design the ears that will be mounted to the spars so that they remain flush with the skin on top of the fuse. Make sure that you get a good seal around the ear-skin junction and make sure that the threads don't let rain water in. That way you don't have anything sticking up into the breeze, but also don't really have to do any work to hook onto the airplane. Of course, this is all probably nonesense, because the area of the airplane behind the windshield probably has a pretty deep boundary layer, or even turbulence. You could probably hide anything up to an inch thick there w/o any aerodynamic penalty. You could mount tie down loops off your Cessna struts up there with no loss of speed. +++ #11059 From: Budd Davisson Subject: Re: Lift straps You don't need much to lift an airplane because you're talking about a dead load with no G factors to worry about. A piece of .090 4130, 1" wide (don't forget to add width for the hole. 1" plus hole diameter) will hold (wait while I get out the calculator), 8100 pounds before it breaks (ultimate, roughly 6000 pounds to yield). And there will be one on each spar bolt. We're talking empty weight here so about 1500 pounds has to be lifted (plus float weight). If you take a piece of .090 and fit it under the head of the spar bolts, then heat and twist it so the part sticking through the fairing is edge to the wind, you'll have plenty. I don't know how much distance there is between the bolt and the fairing to make the twist (there may not be enough and the twist shouldn't be too tight). If there's not enough room, weld up an angle. One inch of weld with a 50% safety factor (read that as screw-up factor) in .090 is still good for 4,000 pounds. So, if you only figure the front two, you still have a 200% safety factor at 2000 pounds empty. If you're thinking about floats, put the lift points on and leave them on. They also make a good place to hang coon tails, which look very cool (unless you're a raccoon, of course). +++ #11061 From: Del Rawlins Subject: Re: Lift straps > What we say that someone come up with a "standard" lift modification, > run it by the Bob and publish it. That way, we won't have an airplane > end up on top of one of our builders. It needs to be stainless steel or maybe 6061 aluminum for corrosion resistance. You could make them out of steel and they would be plenty strong, but when you actually used the points you would scratch the paint off and get rust in short order unless you touched up the paint every time. +++ #11065 From: Ken Beanlands Subject: Re: Re: Standard lift straps > I don't think I will ever need floats or skies, but like the idea of a > full-up instalation for floats, right to the aircraft mounting points > using specialized gear legs. In this way, once the floats were > rigged, they would remain as a unit. I was also thinking that the > brake lines would need fittings to allow easy change out of gear > configurations. This could work on a plane like the Bearhawk where the LG legs can be inserted vertically from the bottim (unlike a C-180 that uses a "porkchop" LG stub that inserts into the lg mounts. Remember that in addition to the struts, there are also two sets of streamlined wires that run between diagonally from the top of the left float to the right side of the fuselage. In fact. it's these two sets of cables that rig the floats. On a 180, they have to be removed to remove the floats. They are hard to see, but check out the top two pics to see them on the front of our 180: http://www.spots.ab.ca/~kbeanlan/personalpics.html You could do this with the Bearhawk but you would have to add a strut to run between the top of the N struts so that you could keep the wires attached. Another interesting adjustment that can impact aircraft performance is the float deck angle. This is the angle that the top of the float makes with the longitudinal axis. For maximum cruise speed, you want a deck angle such that the least amount of frontal area is presented to the airstream. However, for maximum take-off performance, the deck angle has to be significantly higher so that you can rotate to a sufficient angle of attack without burrying the tails in the water. I've flown 2 172's on identical floats with two different deck angles. The one with the lower deck angle took off twice as long as the other, but cruised about 10 mph faster. Kinda like that flap reflexing thing. If I are going to install floats (especially if I were the first to install floats on a BH), I would certainly use an adjustable rear float strut (maybe with a Piper style fork and barrel). Steve Whitenect did some experimenting with this when he first put his Christavia MK 1 on floats and there is a great deal of compromise between TO distance and cruise speed. +++ #11066 From: Ken Beanlands Subject: Re: Re: Standard lift straps > Also on my list are hard points for the installation of steps to allow > "over the wing" fueling without a ladder. These would be removable > since I think they would look hidious. The entry steps themselves I've often wondered about adding a lightweight ladder that could tuck away into the top of the float for exactly the same purpose. There's nothing I hate more than climbing up on top of the wing to refuel the 180. I just know that one day I'll permanently bend something with my weight on the wing, but there is no other safe way to do it especially from jerry cans. +++ #11070 From: Benton Holzwarth Subject: re: Lift Fittings (was: Erbman's Silly Responses) >> Funny how that happens. Don't forget to include the lifting points on >> top of the fuselage so you can change between them. When I went > My idea was instead of leaving lift points out in the airstream > constantly causing drag, I would create some devices that would fit > under the front and rear spar attach points I was thinking about welding cleats to the fuse for this. My thought was that it'd be only for very occasional use -- like if the plane needs to be helicoptered out of somewhere. I was envisioning something that would be out of the slipstream, but would require (for example) cutting fabric to access. I like the idea of something more easily available, good point about lifting rather than jacking when working on the wheels, etc. Seems like some aerodynamic 'caps' could be made to slip over the exposed fittings to clean them up once the plane is flying, during the 'drag cleanup program'. +++ #11252 From: Budd Davisson Subject: Re: Re: Turbines, plans, and M14's > On the topic of the back doors: Is there any reason they need to be on > the passenger side? (Apart from that they are there on a Maule.) I > realize I haven't looked at the plans yet, but I'm thinking I would > like them on the pilot side instead. I don't see any structural reason other than you'd have to swap truss patterns left to right. +++ #11253 From: Benton Holzwarth Subject: Cargo Doors (was: Turbines, plans, and M14's) I bought the cargo door plans, and intend to put it on the right side. Here's my reasoning: I have just one kid, so expect to put only one seat in the back. Since this seat would only be occupied, presumably, when the front-right seat is also occupied, putting the rear seat on the left lets the two passengers talk more easily. Then with the cargo door on the right, it's easier to load bikes, etc, past the rear seat. My two cents. +++ #11254 From: Ken Beanlands Subject: Re: Cargo Doors (was: Turbines, plans, and M14's) I like the idea of putting the rear doors on the left due to my experiences while float flying: When flying solo and docking the plane, you have to shut down and scramble out of the plane and run to the nose (or tail) before hitting the dock. that sometimes means swithing front seats while taxiing. When flying with two people or more, I like to use the passenger to assist in docking so that I can stay in control until we are secured on the dock. With two on board, I try and dock on the RHS whenever possible. With the cargo door on the left and a folding seat on the right front, the passengar can easily scramble into the rear left seat to handle a docking on the LHS. With two passengers, both sides are covered. Normally, I tend to dock the plane when approaching on teh LHS, but it can be tricky in high winds or tight coves (especially whene there are hungry rocks below the surface waiting to bite the floats). I even fell off teh float one afternoon when I attempted docking in high winds and in a tight cove and didn't quite make it to the dock. I slipped off teh tail of the float while trying to steer it clear of some rocks. fortunately, it was only 3-4' of water ;-). In fact, if you look closely at the picture of me standing on the 180 on my homepage, you may notice that my jeans are soaked. Yup, that pic was taken an hour or so after the incident. >>> 20may03 #11298-18250 +++ #11573 From: Jimmy Mathis Subject: Re: Re: why dimples? Next question. Since you brought up drag, I have wondered about vortex generators. Would they be good for the BH? Jimmy +++ #11575 From: Budd Davisson Subject: VG's Ah, the never ending argument about VG's. There's no doubt they let some airplanes hang on to a higher AOA, but, if that means you can't see the end of the runway over the nose, what did you accomplish? I'm certain this'll start a long thread. bd +++ #11576 From: Tony Dean Subject: Re: VG's Ok here is the first in what will probably be a long discussion. It was my understanding teh VGs tended to help when there is flow separation problem and not all wings will benifit from adding them. The only real way to find out is take pieces of yarn out and attach them to the airplane (See Kent Poser: Speed with economy on this technique) and see where flow separation occurs and where turbulance is significant. Now I know that a Quickie driver claimed they helped a lot, especially in rain. Have no idea what they will do to a BHawk. I think any discussion on VGs for the Bearhawk will be pure speculation until someone actually does some research into the flow characteristics of the wing and validates VG and non VG performance characteristics. Regards Tony Dean +++ #11578 From: Brian Cox Subject: RE: VG's My 2 cents worth on Vortex Generators: I'm not sure how much a Bearhawk would benefit from VG's. I bought my 310 two years ago and immediately bought and installed a VG kit. The key advantage they bring to twin operations is controllability. Reduced Vmc gives more safety margin. At my home field elevation of 5650 MSL, Vmc is below stall speed now. If a builder would want to install them on a BH, there has to be some science behind selecting the location of the devices. If they aren't positioned correctly, the results may make handling worse. After all, my kit cost $2500 for a few ounces of aluminum extrusions and some epoxy. The valuable component was the template, that allowed the aluminum parts to be located where they would work their magic. A lot of research went in to developing and certifying the kit. I think they were worth the price on a twin. For the Bearhawk, I'll pretty much follow the plans - it will take some time at the stick to determine if I need to improve the short field performance over stock. Brian Cox, #478 +++ #11581 From: "Lee H. Erb" Subject: Rivet heads and Vortex Generators Here I go agin. Russ will probably correct my spelling, grammar, etc. When we did wind tunnel tests on the fuselage of what became the UH-1D, I did a number of boundary layer studies, both mathematical and wind tunnel measurements. With theoretical Reynolds number changes in the boundary layer thickness I was able to show the drag effects of door hinges, rain gutters, antennae, beacons, aft fuselage shapes, etc. (The wind tunnel people thought we could not do it but they were willing to take our money and we did it.) Later we calculated that the first 6 feet of the HueyCobra fuselage (175 mph V max) should be flush riveted to reduce drag. I think that it was at 120 knots where rivet heads on fuselages showed an increase in drag. Rivet heads cause increased drag two ways. First they trip the laminar boundary into turbulent boundary layer. (In civil engineering hydraulics the transition is referred to as the "hydraulic jump" seen in fast flowing streams. Civils want it, Aeros don't. Another story.) The turbulent boundary layer has a higher skin friction drag on smooth skin. The velocity distribution of the turbulent boundary layer is such that it has higher velocity closer to the surface. This higher velocity can then impinge on the protuberances (rivet heads) and cause dynamic pressure drag. Literature will draw laminar boundary layer thinner than turbulent boundary but they don't always show the relative velocity distribution near the surface where there might be a protuberance.. At some distance (or speed) the turbulent boundary layer becomes thick enough that small protuberances such as rivet heads are below the high velocity and thus do not effect drag. Turbulent boundary layers will remain attached flow around curves better than laminar. Turbulent BL will remain attached (below compressibility onset) for an angle change of approximately six degrees. (Now you have my professional secret.) Above that angle the flow tends to separate and then you have buffeting or control ineffectiveness such as loss of aileron control. This also why the 23012 airfoil has a sharp stall due to leading edge separation and the 4412 has a trailing edge separation and a mild stall. Then comes the Flight Test Engineers fix because the shape (including shape due to angle of attack) induced separation. VORTEX GENERATORS. Many of the business jets and airliners have vortex generators ahead of the control surfaces to put energy into the boundary layer to keep the BL attached. This separation in some cases is induced by compressibilty. Russ's Masters Thesis was on the shape of strakes on the F-16 to provide a vortex on the inboard portion of the wing at high angles of attack. The F-18 had problems until they got the correct shape for the fuselage strake. (The T-37 forward fuselage strake was for another problem, and another story). FOR THE BEARHAWK: (1) NO VORTEX GENERATORS !!! (2) Flush rivets on the wings is the best way to go aerodynamically. Trailing edge in front of ailerons, and aileron trailing edges it is okay to use brazier head rivets. (I don't like round heads in the airstream.) Observations: > From what I have seen on wings of B-17's, I believe the braizer head > rivets lowered the cruise speed. > From what I have heard of the Quickie and other Burt Rutan designs, > they tend to suffer from laminar flow separation. Laminar separation > can be caused by rain, or even dirt. I have heard where grass on the > canards caused laminar separation and prevented generating enough > lift for rotation on takeoff. Vortex generators forcing a transition > to turbulent BL will help in this case but you increase drag some > minute amount. Lee (Now I gotta go study for tests in Plant Diseases and Pesticides. You can take a boy out of the country but you can't take the country out of the boy) +++ #11772 From: "petpatter" Subject: Bearhawk on floats I've been going over the float section on the bearhawk CD, and was wondering if anyone has made any further research on plans building ones own amphibous floats? What about fuselage attach points? John +++ #11773 From: Budd Davisson Subject: Re: Bearhawk on floats the fuselage attach points (bushings in the fuse and a heavier piece of tubing) are part of the plans now, I think. Or they're in a Bear Tracks. Anyway, they exist and, in fact, are incorporated in all of AviPro's kits I know The Bob has done some preliminary float analysis, but I don't know if he's actually designed the fittings or not. I'd think that would be a function of the types of struts used. The fittings would be pretty easy to design, if Bob hasn't done it. bd +++ #11787 From: Del Rawlins Subject: Re: Bearhawk on floats > I know The Bob has done some preliminary float analysis, but I don't > know if he's actually designed the fittings or not. The Bob has said to use front landing gear attach point as the front mount, and that the rear mounts can be made the same as the front. I can't remember if that was in the newsletter or what. I think that it resulted from questions from the email group that Mike Meador presented to Bob, whose answers he posted back to the group. In any event it is a simple solution and is what I am planning to do, at the cost of a small drag penalty. Since I'm planning on spending most of my time on floats, the drag penalty isn't a huge issue. I was under the impression that Proto 2 uses the cargo tie down points as the rear float mounts, as shown in the newsletter. That is probably a good choice for an airplane that probably won't spend much, if any, time on floats. It will give you the capability of adding them later on without making any fuselage mods, and not incur a drag penalty in the meantime. Personally I would rather not need somebody inside the plane to hold a wrench on the bolt heads while I install or remove the floats, particularly since the plane will be hanging from a hoist at that time. In that case I would design the attach points on the float rigging as fittings that could be installed prior to lifting the plane and removing the gear. -- Del Rawlins +++ #11847 From: "Tim Anderson" Subject: Re: Bearhawk on floats One also has to give thought to where the water rudder pulley attachments will be. One can sort of eye-ball a cable run forward from the rudder to the rear float attachment point and see if pullies on the fuselage side are required...or if one desires to drop the cables down from the fuselage side to a point directly on the float deck with cross over cables as required. ie.. weld pulley brackets on the fuselage side. I saw a C206 on amphibs that actually had the cables inside the fuselage and float struts which will eliminate drag, stepping hazzards and possible cable damage. very elaborate planning required. Also, one may want to think ahead and plan for the routing of the water rudder lift cable run back into the cabin. If one plans ahead that will preclude cutting into fabric to retrofit. TA #398 +++ #11909 From: Del Rawlins Subject: Re: Bearhawk on floats > Also, one may want to think ahead and plan for the routing of the > water rudder lift cable run back into the cabin. If one plans ahead > that will preclude cutting into fabric to retrofit. Since you have to incorporate a control for raising and lowering the water rudders anyway in a seaplane installation, the same control and some of the cable run could be used to lock and unlock the tailwheel. We all know that the Bearhawk doesn't need a locking tailwheel, but if you wanted to have one, *and* the ability to run floats, that will save on adding a separate control and part of the control cable run. Since the tailwheel will be removed when switching to floats, somewhere in the middle of the run the cable would be unhooked and the aft portion removed with the wheel/spring assembly, and the remaining portion could then be hooked up to the water rudder raise/lower mechanism. -- Del Rawlins +++ #11920 From: "Tim Anderson" Subject: Re: Bearhawk on floats Another factor one may concider with floats is to have the rudder horn extra wide..as in several inches..to allow for a greater stoke distance when connecting the water rudders. When I first installed my water rudder cables, the normal rudder cable stoke only moved my water rudders about a quarter of the full defection. I added a extension on the rudder horn of about 6 inches per side to acheive full water rudder deflection. TA +++ #12006 From: Del Rawlins Subject: Re: OT(a little) to fill the silence: Vortex Generators and Ice > I had a discussion with a friend a few nights ago about vortex > generators. He is absolutely against them because he feels that if > one runs into icing that the generators will ice up much and destroy > the lift whereas the un-augmented wing, even with a heavy layer of > ice, will continue to maintain its airfoil shape and provide lift. > > Any thoughts on this. I was planing VGs on my Piper airfoils to > improve real STOL performance. Interesting that you would mention this today. An acquaintance of mine was a passenger yesterday on a Navajo somewhere out in the bush where they ran into icing conditions. The pilot did a good job keeping the leading edge clear with the de-icing boots, but what he noticed from his vantage point over the wing was the ice buildup on the vortex generators. He said that the ice built up almost perpendicular to the VGs in thick layers. They did make the runway but both engines were firewalled in order to maintain altitude. I asked an A&P friend of mine whether VGs do any good (he had a cub equipped with them in his hangar at the time) and he told me I was better off learning to fly the airplane. 8^) Also they will do bad things to your wing covers. -- Del Rawlins +++ #12011 From: "Bruce A. Frank" Subject: RE: OT(a little) to fill the silence: Vortex Generators and Ice My desire is to keep everything energized for control at very slow flight. I have ridden in a J3 Cub before and after the installation of VGs. The differences in take off and landing speed were undetectable, but the feeling of solid control right at the stall was fantastic. I have had a similar experience in a C172 where there actually was a 3-4 knot reduction of landing/stall speed with similar improvement in handling. Ninety percent of my flying will probably be in the lower 48 with no plans for IFR work. Bruce A. Frank +++ #12345 From: "Vuxton, Christopher" Subject: Lurking other Websites I don't know how many of you stary afield but I've been watching Rocketboy (who is this guy?) at http://www.f1-rocketboy.com/ building his Harmon Rocket (Bearhawk on steroids, not) . This is a great site with lots of ides. Here is an example of things he's doing that could go in a 'hawk: Fire Detection After a friends Velocity engine caught fire inflight, I started giving a lot of thought to a fire detection system. Just snooping around a little bit, I found out that all new light aircraft have fire detection systems. All the aircraft I investigated use the same type of system. They use a simple thermal switch to detect an over heat condition presumably caused by a fire. Purchasing a system from an aircraft maufacturer for a single sensor and a red light cost a staggering $4000. Holy Sh#t !! After speaking to knowledgable people on the subject, it was determind that the following was needed: The highest average cowling exhaust temp must be known. Then a buffer was added. The recommended value was 50 to 100 deg F. The switch needed to be a rugged normally open SPST device that closed at the desired temperature thus illuminating the FIRE light. FWIW, I decided 'ask) the highest exhaust temperatue to be 200 deg F. I had a switch custom made to close at 300 Deg F. This gave me a 100 degree buffer and makes me confident the thing will never give a false warning. The system had to have a closed loop test function to ensure all wiring to the switch and back was in tact. I added an aluminum heatsink to the sensor to insure it got the heat changes as soon as possible from the airstream. I even used some heat sink compound to reduce the thermal impedance. I want as quick of notification as is possible! Bottom line: 300 Degree sensor $0 free. Got it as an engineering eval unit. Heatsink $.75 Wire $3.00 Bright red FIRE LED $.55 Press to test switch $3.00 Total cost $7.30 Plus about 3 oz. weight for piece of mind. This is the switch and the heatsink Here the completed sensor assembly has been installed in the cowl air exhaust flow area. The sensor is held to the heatsink with two -8 stainless screws. Note wires heading for the cockpit. This allows closed loop testing of the entire system during preflight. A slightly different view showing the heatsink contact area. +++ #12353 From: Russ and Penny Erb Subject: Under fuselage hardpoints Finally the pictures are back so I can tell y'all about this (my digital camera has gone back to the shop to fix under warranty again what they fixed a couple of months ago 8^( ) A while back we discussed under fuselage hardpoints (attachment points) for hanging baggage pods, fuel tanks, bombs, or whatever. I had thought of all sorts of ideas but none of them worked, because it was either too complicated or there was something else in the way (like control cables). I got to thinking that the mounts for the tie down rings (which also hold the rear seat in place) as done on Proto II are threaded all of the way through so that bolts can be threaded in from the bottom. With a spacer tube over the bolt, these could work just fine as the aft hardpoints for an under-fuselage pod. Now all I needed was forward hardpoints. In a brief moment of inspiration (perhaps when asking "What would 'The Bob' do?") I came up with the idea shown in the small attached jpeg. I really like it because it is a simple and elegant solution, thus in keeping with the rest of the airplane. I used a short piece of T11 tube with a threaded tube (weld in and tap threads) through it near the wing strut attachment. This is as far forward as you need to go because a pod going any farther forward would interfere with the landing gear shock struts. Yes, I know this violates the rule of only applying loads to a truss at the clusters, but not any more so than the other tie down points or seat belt attach points do. I'm pretty sure the tubes in this area are strong enough to take a little bit of bending loads. Remember, the weight penalty is small if you never use it, but if you use it just once, think about all the pain and anguish you'll avoid by doing it now than trying to retrofit something later. Kind of like that float ventral fin mount I'm installing but will likely never use. Russ Erb +++ #12355 From: Budd Davisson Subject: Re: Under fuselage hardpoints The hard point thing is a good idea and your attach points will hold more than the airplane can lift. I think the BH is ready made for a plywood rack like Cubs use, but that's going to require coming up with a lateral truss that bolts to your hard points to limit sideways movement and keep the load below the belly line. The Alaska hands have seen it many times, but it's pretty cool to see a Super Cub takeoff with a bunch of 4 x 8 plywood sheets slung underneath in the rack. Of course, one of the downsides to the BH single, aluminum strut is we can't weld bushings through them and used them to tie loads to. With the BH, I guess we don't need it. The Cub does. bd +++ #12460 From: Budd Davisson Subject: Re: [Bearhawk] OT: floats, etc. > How are your demonstrators coming along? Perhaps one of them could > be set up on floats when finished, I love the idea. I hate the concept of throwing yet another log on a fire that's already causing my eye balls to sweat. Tell you what though: since there are so many people on this e-group who know floats intimately, I'd love to get some education on the different types (EDO, Wipline, Murphy, etc), pros and cons as well as some telephone/e-mail contacts with those who would be able to help us most when the time comes. I know most of the basics, but not the details. bd +++ #12465 From: "Brian Cox" Subject: RE: [Bearhawk] OT: floats, etc. Tom Young, a member of chapter 43 finished a plane similar to a Bearhawk about a year and a half ago, then flew it to Alaska. He had a set of the Full Lotus inflatable floats for it. He used a fuselage from A&E in Seattle, and a Riblett wing. Power was a Lycoming 0360 with fixed pitch prop. He called the plane the Arctic Fox. Beautiful workmanship. Brian Cox +++ #12734 From: Del Rawlins Subject: [Bearhawk] Re: AviPro Wing Test & newsletter > Great news Budd. It sounds like a gross weight increase would be a > possibility if the landing gear are up to it. Or what is the allowable gross weight of a float equipped Bearhawk. Who cares about the wheel gear? I'll be building them but mainly so it has something to sit on while I build the floats. 8^) -- Del Rawlins +++ #12740 From: Budd Davisson Subject: Re: Re: AviPro Wing Test & newsletter From the beginning Bob has said the float equipped BH had a higher gross weight. I've never heard an exact number but 2650 seems feasible. bd +++ #12746 From: "Penner, Larry" Subject: Utility door Can the Bearhawk's utility/cargo door be installed on the left side rather than the right? I've heard a few 206 drivers bitch about falling in the drink after climbing over and under the airplane when docking. Granted, they don't have a front right hand passenger door for egress. Also after reading the horror stories about well intentioned passengers getting whacked by the prop while trying to help at the dock I was curious. Larry Penner +++ #12747 From: "Bruce A. Frank" Subject: Re: Utility door Certainly I am not the designer, but from a structural stand point there is no reason not to construct the fuselage with the cargo/utility door on the left rather than the right if that fits your need. Bruce A. Frank +++ #12748 From: Russ and Penny Erb Subject: RE: Utility door I'm pretty sure this has been asked before, but I can't find it. As I recall, the consensus was that if you merely built the fuselage as a mirror image of the plans, it should work just fine. Just beware of confusing yourself. Russ Erb +++ #12787 From: Russ and Penny Erb Subject: Cargo Door Tube Twisting For those of you who have built the cargo doors... How did you orient the square tubes? It seems that if I put them flat against the flanges (with 1/8" gap), the sides of the tube won't be flat against the skin. To get the tubes flat against the skin would seem to require angling the tubes out relative to the flanges. Please tell me about what you did with the tubes to get the skin to attach cleanly. This is another one of those subtleties that I never bothered to notice. Russ Erb +++ #12788 From: "Bruce A. Frank" Subject: Re: Cargo Door Tube Twisting Though my cargo door is different, it required orienting the square tube I used, for both the frame around the opening and the door itself, to make it fit the angle of the skin. In my construction my stringers form three facets on the aft section of the fuselage requiring not only orientation of the tubes to match the fabric surface planes in each of those facets but the frame and door itself is multi-angled to match the three facet shape....I got in deeper than I intended, but it has been that way with almost every aspect of construction. Bruce A. Frank +++ #12789 From: "Bruce A. Frank" Subject: Re: Cargo Door Tube Twisting Let me add that the bottom square tube on my door actually has to be "twisted" about 5? from one end to the other over a distance of about 3 feet to lay evenly "flush" with the skin. Bruce A. Frank +++ #12802 From: "piperthorp" Subject: Re: Cargo Door Tube Twisting The top and bottom tubes are most of the problem. The verticals seemed pretty straight forward. I shimmed the tubing in the frame to hold the tube flat against the skin. Seemed to work OK. The Piper Pacer had the square tubing reshaped to sort of a parralelagram (?) for a nice fit, both to the skin and the frame. I have a Maule M4 in the shop and the rear door has square tubing flat to the skin. Bill Cox #303 +++ #12804 From: pfflyerz@c... Subject: Re: Cargo Door Tube Twisting To jig up the cargo door tubes I clamped them in place with 1/8 inch spacers to all the door sills. This worked very well for getting things ready to weld, but it did present the problem you indicated of having the flat tubes not guite in the plane of the skin. When drilling the skin to the frame I tried making little wedge shims but abandoned that idea as too much work. I found that it wasn't really a problem after all as the pop rivets didn't pull the skin in hard enough to cause it to deform. If you are still concerned about it, just use a small shim on top of the 1/8 spacer to kick the tube out to the angle you want. Pat Fagan +++ #12807 From: Russ and Penny Erb Subject: RE: Re: Cargo Door Tube Twisting Thanx, Bill and Bruce. You confirmed what I suspected. Today I cut the tack welds off and repositioned the tubes and retacked. I shimmed the tubes out to match the angles of the skin. It turned out to not be that much more work, and I'm much more pleased with the results, since I know the skin won't look all goofy when it is screwed down. The outer frame of the rear cargo door is done--the front cargo door will come eventually. Russ Erb +++ #12873 From: Russ and Penny Erb Subject: Rear Door Skin Here's another one of those things that slipped through the cracks on the Bearhawk CD. I throw it out in hopes that someone can answer this. On the plans for the cargo doors, it clearly states that the door outer skin is aluminum, attached to the frame with 6-32 screws. Very well, you say, but that's not the whole story. The forward cargo door has the rear window in it. I can't find any information to answer the question: How does the aluminum skin attach to the rear window frame? Russ Erb +++ #12874 From: "piperthorp" Subject: Re: Rear Door Skin Looking at Bob's photgraphs I never got a clear understanding of his method vs the drawings. So.. I did not form a window frame like the left side. I did the rear door similar to an early Piper. I welded in a .032 channel across the bottom of the window with another piece up the rear of the window. The window is sandwiched between the door skin and an aluminum trim piece on the inside of the door. The door skin attaches to the outside of the channels and the inside trim attaches to the top of the channel. Look at a Clipper through Tripacer. Bill Cox #303 +++ #12875 From: Budd Davisson Subject: Re: Re: Rear Door Skin The door skin laps up onto the window frame and the screws go through the plexi and the frame. You just have to make sure that after you've drilled the initial holes that you pull the window back out again and drill those holes out a couple of sizes bigger to give some clearance between the bolts and the plexi. bd +++ #12877 From: "Dan Montee" Subject: Re: Re: Rear Door Skin FYI, I added a couple of pictures of Proto II's cargo door to the photo file. Dan Montee # 415 +++ #12882 From: pfflyerz@c... Subject: Re: Rear Door Skin I made a window frame for the cargo door, just like the one I made for the left side and welded it in the front door frame. The door skin is attached with pop rivets through the skin, frame and window. Pat Fagan +++ #12889 From: Russ and Penny Erb Subject: Something else not obvious in the plans... Been working on doors. Today I was hanging the rear cargo door. I've been building the doors on the fuselage frame leaving a 1/8" gap per Bear-Tracks. Of course, after welding shrinkage, they end up slightly smaller, but that's not the issue here. In fact, it actually helped. For all of the doors except the rear cargo door, the structure between the hinges is straight. Because of the shape of the fuselage, the structure between the rear cargo door hinges bends out away from the hinge line, which can lead to interference when opening the door. Of course, I figured this out in my standard way, namely after welding the hinges on and the door would only open about 20 degrees. My solution was to cut the hinges off and weld new ones on with about a 1/4" gap at the back of the door. Getting the skin to work will be another interesting problem. Another possible solution would be to move the hinge line farther away from the fuselage. The point here is you should check how this door is going to operate before you start welding the hinges in place. Russ Erb +++ #12891 From: Russ and Penny Erb Subject: Would Someone Please Get This Perfectionist Out Of My Shop?! Yesterday I wrote about a problem with hinging the rear cargo door. On the first try I ended up with a door that would open only about 30 degrees. I cut the hinges off the door and tried again after moving the door forward an extra 1/8 inch. I thought I was done, since the door would open fully. Even so, I was bothered by the fact that when the door was halfway open, the gap between the door and the frame was about the thickness of one sheet of fabric. Knowing that there would be at least 4 thicknesses of fabric in this gap (fabric plus reinforcing tape on both sides), I was bothered all night by visions of you guys laughing at me at the 2005 Bearhawk Fly-In, pointing to where the fabric had been worn away by opening the door multiple times. This has happened several times before--I finish some part and it should be plenty good enough, and I try to convince myself that it is plenty good enough, but some minor detail just gnaws at me until I have the somehow redo or re-fix the part. Fortunately, each time I've done this (so far) it has come out better and I've been much happier with the result (and sometimes even pretty impressed with myself). I'm not saying you have to do this--I just do...and it can be very annoying... Anyway, you probably saw this one coming. Today I cut out the hinges from yesterday and made new hinges with the hinge lines 1/4" farther out from the fuselage. I also moved the door as far forward as I could while still maintaining 1/8 inch around the front cargo door. This resulted in about a 1/4" gap between the rear door and the rear frame (the extra came from the weld shrinkage). These two changes made a huge difference, and the result is significantly better. At least I won't have to cut them off and do it a fourth time! I won't say that you'll need to move your hinge line, because that will depend on your particular interpretation of the fuselage geometry. I will say that you need to carefully investigate the geometry of opening the door before welding your hinges in place. Russ Erb +++ #12898 From: "piperthorp" Subject: Re: Would Someone Please Get This Perfectionist Out Of My Shop?! This sounds so familar. The shrinkage is all that saved me from having to rebuild that door. I was doubtful of the hole location on the hinges so I made them about 1/4" long and drilled my first set of holes 3/32". After finding the interference you describe I welded those holes shut and redrilled. I did this on all the hinges and then cut them to final size after I got the fit I wanted. The baggage door was probably the most difficult for me. The doors were a nice project and I am proud of the fit. Bill Cox #303 +++ #14150 From: "conohawk" Subject: Re: Homebuilt float How about the kit floats from Murphy Air: http://www.murphyair.com/Product_Info/Floats/float_decrip.htm I don't have any detailed information about them, though. I doubt they're inexpensive. Bon chance! -Mark Conover +++ #14154 From: "rodsmith52" Subject: Re: Homebuilt float Murphy makes float kits, in 1500,1800 and 3600 displacement. Either too small or too large for the Bearhawk. I have been pestering Keith at Montana Float company for over 2 years about a 2700 displacement float kit. Currently they have 2200 and 3500 kits. I was really impressed with the 2200s that I saw at a trade show in Anchorage. They say they are going to make a 2500-2600 displacement. I keep telling them to make it big enough for the Bearhawk. Aqua floats makes kits for some of their floats. If you look at their website the largest kit float you will see is 2200. The owner told me he would kit a 2400 float for me (good for 2700 gross). Cant remember the price, I think 7-8 thousand less than a certified set. Also check out the aerocomp floats. I dont know anything about them except what is on their website. Rod Smith #246 +++ #14164 From: "Bruce A. Frank" Subject: Re: Re: Homebuilt float Comp Air of Florida also has kits (fiberglass shells) for both straight and amphibian. Prices, last time I looked, for a 2500 lb gross amphib was around $10,000. Wag Aero has plans for aluminum Northaire floats. A couple of years ago there was an article in one of the mags about a gentleman who designed and built his own plywood floats. He had a program that would create the plans for correctly proportioned floats by just sticking in gross weight of the bird. I had him loft a set of plans for me on 2500 lb gross for a fee of $75. I have a friend analyzing and redrawing with elements of the Northaire floats (for which I also had plans) combined into the final layout. (The engineering of some of the hard points was actually done better on the Northaire than on my custom plans) One of these days I'll let you guys know what we come up with...don't hold your breath. Bruce A. Frank +++ #14166 From: William Didier Subject: Re: Homebuilt float try Wag-Aero in WI...they used to have a set of float plans... +++ #14168 From: "Russ Kaye" Subject: RE: Homebuilt float The Wag-Aero plans are for aircraft up to 1500lbs gross according to their catalog. Russ Kaye +++ #14171 From: "Bruce A. Frank" Subject: RE: Homebuilt float They do include instructions as to how to up size to increase gross capacity by adding a bay in the middle (thus lengthening the float) but the proportions are out of scale to my eye when you do that. The really need to be up sized in all dimentions to make the things come out right ...at least to my eye. Bruce A. Frank +++ #14178 From: "Shawn Burns" Subject: Re: Homebuilt float I am building the float attach fittings on #535. My plan is to make my next project a set of amphibious floats. I spent quite some time when I was in Seattle a couple of years ago riding my bike around Lake Washington and looking at floats. My plan is to take some photos and measurements, read all I can on float design, and develop a float of the proper displacement with provisions for stowing gear within the float compartments. They will need a displacement of approximately 300 gallons or 69,203 cubic inches. This would allow one float to support the full gross weight of the aircraft. When I have run my design through my own test program ( I CAN tear up a crowbar in a sandbox!), I will be offering plans to home builders. I have been puzzled for some time as to why float designs (plans-built, that is) have not been marketed yet in the homebuilt arena. I speculate that one reason is the low volume of interest relative to other avenues. Another reason is I don't seem to find a lot of test and design literature available. And then there are of course the liability issues. Floats have not seen a lot of commercial and military application in a year or two. I am not a financial genius, but would be wiling to bet there is more money to be made in defense contracts and builing heavy iron than in selling float plans to a bunch of aviation extremists growing there own 2024T3 on the back 40. I am not an engineer by profession but mearly out of habit and necessity. I also plan to carry a gold dredge on similar lightweight floats powered by a water-powered turbine of my own design. Then when #535 heads up north of Planter Bob for the summer, I might not come back for a while. A barrel of 110LL, my fishing tackle, some .270 ammo, and my little still, yeah, I just might stay! Let some lawyer serve me papers for a suit regarding faulty design while I'm holding my .270 and cooking a batch of "rhumatiz" medicine on the banks of a remote AK river. Shawn Burns +++ #14181 From: Ken Beanlands Subject: Re: Re: Homebuilt float The biggest problem for larger, scratch-built floats is the multi-chined bottom front skins. Once you get above 2000 lbs, it becomes very difficult to get off the water with a single chined hull bottom (in other words, skins without a compound curve). This is quire difficult to produce in either wood or aluminum (although I'm sure that Kent could pop out a set in an afternoon ;-). Although I'm pretty sure that a single-chined float would work on the Bearhawk, I think that take-off performance would be pretty poor. The North-Aire and those plywood floats are for much smaller applications; 1500 lbs for the North-Aire and even smaller for the plywood floats (they were on a Mini-Max Ultralight). You can also buy plans for plywood floats from Falconar in Edmonton, up to 1500 lbs. Zenair sells plans for aluminum floats up to 1900 lbs. BTW, I actually have the Zenair, Falconar and North-Aire float plans with Zenair certainly being the best designed of the bunch. Ken Beanlands B.Eng (Aerospace) +++ #14188 From: Bob Romanko Subject: RE: Re: Homebuilt float I'm seriously considering stitch 'n glue composite homebuilt floats. Any of you guys boat builders? You can make some sweet compound curves by using two very thin sheets of plywood laid up and glued together just before stitching together with stainless wire and laying up glass and epoxy on the seam. Sure makes sense to me. It's how the bow and bottom of the Tolman Skiff are formed. The Tolman Skiff weight almost half of a comparable aluminum or plywood and frame boat, and it's every bit as strong, if not stronger. Planter Bob +++ #14191 From: Budd Davisson Subject: Re: Re: Homebuilt float don't read anything into the question I'm about to ask: Ken, I know this has been discussed before, but from your perspective as an engineer and float guy, how practical would it be for AviPro to reverse engineer a set of EDO's? And which EDO's would those be? Flat tops? In my mind I see building floats as being as complicated as building the wings. bd +++ #14196 From: Ken Beanlands Subject: RE: Re: Homebuilt float How about doing a cove and bead stripper (no comments please, and no, I don't intend to build floats in the nude ;-) plank method similar to building a canoe. This would handle the problem of the compound curve on the front, lower skins and still allow the use of stitch and glue or traditional plywood construction for the rest. You will probably need some spars to run under the length of the upper skins (at least between the spreader bar stations). You will also need a heavy keel behind the forward skins and skeg at the step. Almost the entire weight of the plane will rest on the step skeg when the plane is out of the water, add in some wind and you can see why it needs to be so robust. The rear keel can be lighter as there is not as much stress back there. In fact, at rest you can usually lift the tails of the floats by hand. You should probably have some stringers backing the chines for support as well. If I were to pursue this, I had planned to make the forward skins by forming them over the frames, glassing the bottom, remove them from the frame and glass the insides. Then they would be applied to the floats as a finished piece. If you were to use the shape of something like a CAP 3000, there's no reason why you shouldn't get the same performance. BTW, it's usually OK to overfloat by up to 10%. Generally, the performance is a little better and there is less of a chance of sinking the end of the float when stanting on the tails. Of course, there is a minor weight penalty. However, underfloating can have detrimental effects. One set of floats that you could probably get relatively cheap is the Edo 2790 electric amphibs. These floats are essentially a beefed up 2870 with the amphib gear. Since there is a sealed hole in the float, behind the step, for housing the main gear. This is where the 80 lb loss in floatation comes from. These were originally designed for the 180, but tended to be a bit too small for the later models with 3000 lb gross weights on floats. We originally bought a set that had been on a C-180 on one of the mid-west rivers during a flood. When the storm started, teh owner moved the plane into the hangar. Flood waters eventually floated the plane and crushed it into the ceiling of the hangar! The floats were undamaged. The set changed hands several times before coming to us. By then the floats were missing a lot of the amphib gear and the cost to replace the stuff was more than a set of good 2960's. We traded the 2790's plus the original, very damaged 2960's for a set of good, tight 2960s that are still on the plane today. This was probably a good move since the plane, on strait floats has only 1000 lbs useful. Full tanks is over 500 lbs leaving around 480 lbs. Add in another 200 lbs for the amphib gear and you're at 280 lbs....a good single place airplane. Granted, you could alwas sacrafice some of the 80+ gallons for more useful load ;-) Ken Beanlands B.Eng (Aerospace) +++ #14198 From: Ken Beanlands Subject: Re: Re: Homebuilt float It shouldn't be that hard. Most of the popular floats (Edo and CAPS) available under 3500 lbs are round topped. However, I believe that Wipline (Wipaire) 3000's are flat topped. I know that all the Aqua floats are flat topped, but they only make a 2400 and a 3190 (probably a bit big for a BH). Personnally I think the only hard part of this would be forming the front lower skins. I talked to Eddy Peck in Bear River, Nova Scotia about this and he had come up with a press to make the skins for his float kits. Essentially, he is doing theis already. There is also another company in Quebec and one in Ontario that are also making replica float kits. I've seen them advertise in COPA. Personally, I much certainly prefer flat topped floats, but they are so hard to find in the C-180 weight and Bearhawk Weight range. Probably the best bet is the Aqua 3190's or 2400. BTW, Aqua does sell their smaller floats (950's-2200's) in kit form. It might be just simpler to talk with them and have them prepare a kitted 3190 or 2400's. According to their site ( www.aquafloat.com ), 180% of gross weight of the aricraft must be provided in boyancy. In other words, the 2400's would work on a BH, as long as the gross weight was limited to 2667 lbs. They also list the installed weight of the 2200's as 305 lbs and they are very clear that this is the weight of their floats and all the rigging and does NOT account for the weight benifet of removing the landing gear. They also quote a build time of 600 hours. I would extrapolate that the 2400's run around 340-350 lbs. Another interesting point is that the finished 2400's, complete with rigging, cost about $19,000 USD. With enough interest in Bearhawk floats, they might be interested in coming up with a set of 2700-2800's to augment their line.... Ken Beanlands B.Eng (Aerospace) +++ #14204 From: Ken Beanlands Subject: Re: Re: Homebuilt float One other nice thing about the Aqua (over the Murphy) is that they use 2024 skins, not 6061. Ken Beanlands B.Eng (Aerospace) +++ #14208 From: "Bruce A. Frank" Subject: Re: Re: Homebuilt float I do understand the strength advantage of 2024 over 6061 and the weight savings that can also be achieved by designing with material thickness strength in mind, but after that first slide up on the beach 2024 corrodes at a much higher rate than 6061. Let me comment about the floats designed around the plywood lofting program I mentioned earlier, my intention was not to build with plywood but fiberglass, kevlar and carbon fiber. The changes that need to be made, hull shape and step, to get off the water more quickly is why we are reviewing the design and combining features from available sources about float technology. My original concept was to create WELDED aluminum floats with 6061 T6. I am not convinced that it cannot be done but my time and capital has caused me to pass the project along to evaluate and redesign for probable construction from composites. If anyone can point me at a set of plans for composite floats in the 2200 to 2700 lb flotation range I'd dance at your wedding (actually taking pictures for you would likely make you happier). Bruce A. Frank +++ #14209 From: "Luc Morin" Subject: Re: Re: Homebuilt float I did rebuild my EDO 1320 when I buy my cub 20 years ago. The float where from a salvage and as it is a flat top it is very simple to work on. You put on a long and flat table your bulkhead upside up and you build it... Finishing in by returning every thing and installing the top. As you can see it was a complete rebuild base on the copy of the parts from the left float parts. The right one was nothing more than a small aluminium ball... It is simple to do but with very confined space, but that some thing that an average builder can do. Coping parts is a litle more complicated and getting plan would be a lot simpler... +++ #14210 From: Ken Beanlands Subject: Re: Re: Homebuilt float Although corrosion is an issue (usually on the steel fittings of the float, not the aluminum skins and forms), it is not what causes most floats to be junked. Long before corrosion has made the floats skins unusable, they typically have to be replaced due to damage. Floats, like an aluminum boat, takes a lot of bangs and dents on teh bottom of the hull through it's life and eventually become loose (rivet heads damaged and leaking, keel/skin seam leaking, creases along the hard chine, etc) all work to cuse leaking inthe floats. Eventually, the floats come off, and the skins are replaced. I do have a concern with just how well fiberglaloats will handle thes bumps and bangs form ground handling. All it takes is to come into a dock a little hot or angled a bit off and you've just put the hard edge of the float into the dock. Having seen this happen twice, I'm not so sure how well a fiberglass float will fair. the aluminum buckled in about 3 inches and popped back out, leaving a permanent crease, but no subsequent leaking. I don't think that fiberglass would have done as well. For fiberglass to be strong enough, I think it would end up being more fragile than aluminum. Besides, the floats we have on the 180 are about 35 years old, made from 2024 and have no sighs of corrosion despite being run up onto lots of beaches. they are still tight, despite the crinkle on teh nose ;-) Ken Beanlands B.Eng (Aerospace) +++ #14212 From: Del Rawlins Subject: Re: Re: Homebuilt float > I do have a concern with just how well fiberglaloats will handle > thes bumps and bangs form ground handling. Somehow fiberglass boats seem to survive untold numbers of hard arrivals at the dock each year. Granted, most of them are built heavy, but I know that I've hit rocks with my fiberglass canoe that would have permanently deformed an aluminum canoe, and the glass canoe just bounces off. The worst thing that happened was we put a dent in it last summer that popped back out easily (I'm planning to put a reinforcement on the inside in that spot, just in case). What concerns me more with glass floats, is that because the aluminum will deform more easily in the event of an impact, with a glass float more of that force will be transmitted directly to the airframe. An incident that might have required only float repairs could have more serious consequences. Another issue that has been raised by a float pilot I know, is that composite floats tend to have much lower drag than aluminum floats, which can make slowing down on the water interesting. That said, I'm still planning to build composite floats for my Bearhawk. -- Del Rawlins +++ #14213 From: "Matt Prather" Subject: Re: Re: Homebuilt float Building a composite "knockoff" of something that was originally metal requires engineering - intimate knowledge of the materials. That's why fiberglass things are often floppy and overweight. When done correctly, a composite structure can be incredibly abuse tolerant. However, once a composite structure has been deformed beyond elastic recovery, its strength is usually severly reduced. The same thing happens to Al, but sometimes to a lesser extent ("just popped the dent out and kept going"). Like with other materials, you can design regions of a composite structure to be flexible and abuse tolerant (along the bows and gunwalles) and other places to be stiff and sturdy (along the bottoms). The other nice thing about composites is that there you can mix and match materials based on their mechanical properties. A layer of kevlar makes something very abrasion and tear resistant - perfect for under the 'Vee' of the float. An interesting testament to the strength of a properly designed composite structure is related here: http://www.ez.org/flightto.htm I realize probably none of you are enamaoured by plastic airplanes, but when properly designed, they are tough. LongEz gear are light weight, aerodynamic, and pretty stiff, but apparently fairly flexible when pressed. Regards, Matt Prather +++ #14217 From: Ken Beanlands Subject: Re: Re: Homebuilt float I don't think you'll have ANY problen stopping no mater what the surface drag. Floats stop by form drag. Pretty much as soon as you're on the watter with that byg prop at idle and all that flap hanging out, you yank back on the column and trive the tails of the floats deep in the water and you're stopped. Most floatplanes will stop in a fraction of the distance of a wheeled plane. Well, let me rephrase, most floatplanes can decelerate to walking speed in a fraction of the distance of a wheeled plane. Stopping the plane entirely is a whole other story ;-) Besides, if you're worrid whether or not you have enough room to stop, then most likely you will NEVER take off out of there. The 180 will go from 60+ mph to about 5 mph in less than 300'. Even my shortest take-off's are more like 1000'. I have not problems with a smooth bottom (No cracks here plese ;-) as it will generally allow you to take-off quicker. In fact, Lake and Air used to sell a tape that you applied to teh bottom of the hull to decrease float/watter drag. As you have said , most fiberglass boats in the same weight range have very heavy hulls compared to floats. Ken Beanlands B.Eng (Aerospace) +++ #14218 From: "Bruce A. Frank" Subject: Re: Re: Homebuilt float The utility point between strong enough and light enough is a major concern to me, I have seen a set of floats that demonstrated puncture resistance that exceeded that of aluminum floats by using Kevlar and a "softer" epoxy that flexed dramatically before giving up. Your experience with 35 years of service with aluminum floats is encouraging. I went to a seaplane base years ago and saw several sets of floats laid on saw horses with for-sale signs on them. All of them had corrosion significant enough that thinning and subsequent cracking was visible on all on display. (Majority were Edos) Don't know how old any were but the sight of all those floats with bottom hull corrosion significant enough to effect structure rattled me a bit. Heck, rattled me a lot... particularly when most were still priced above $15,000...even with corrosion holes. Does anyone know of plans available for aluminum floats in our weight range? Bruce A. Frank +++ #14220 From: "rodsmith52" Subject: Re: Homebuilt float The gross weight on Maules with Aqua 2400s is 2700#s. One Maule pilot I know swapped from EDO 2450s and said the aquas could carry a lot more and got off the water faster. Since Bob says the Bearhawk gross on floats is 2700, they should be a good match. I talked to the owner of Aqua floats at Sun&fun 2001 and he said they would kit the 2400s if you want. Rod Smith #246 +++ #14221 From: "ken wardstrom" Subject: homebuilt floats Bruce, you may want to get ahold of mike hirshfeild. I believe he was going to sell either the plans or kits for his floats, and they are the exact size for the bearhawk. They are also the most incredible floats i've ever seen. His original floats had wheels that he bolted on for the winter, but his new ones were completly amphib. Pretty neet to watch him land on the river with the wheel gear down and not flip over. - ken +++ #14222 From: "Bruce A. Frank" Subject: Re: homebuilt floats Gee, I talk to Mike on the phone every once in a while and he has never said that he offered either plans or kits. I knew that he had built a set for his first Ford powered plane (the picture I posted on the Bearhawk Yahoo group site) and later had those up for sale because he'd made some changes, but plans and/or kit you say....Man, nobody tells me anything!!! +++ #14233 From: "ken wardstrom" Subject: homebuilt floats Bruce, i may have gotten things wrong regarding mikes floats re: plans or kits. - ken +++ #14234 From: "John T." Subject: composite floats Composite floats should be workable. Use Kevlar near the bow for puncture resistence, and carbon fiber for strength where needed. Use fiberglass everywhere else. John +++ #14237 From: "Dan Montee" Subject: Stitch & Glue Floats I tend to agree with PB, stitch & glue may be the best choice for a kit float. I helped build a canoe using this method about 30 years ago before the resins of today were developed. That canoe was lighter than our comparable aluminum canoes and took all the abuse the aluminum did and it wouldn't dent. Like the good Planter I'm thinking of taking a 6 month hiatus from the BH to build a S & G boat. My mission is different. My intended use is on Charlotte Harbor FL. I chose a boat (GT 23) offered by http://www.bateau.com/index.html. These guys are successful boat designers. My thought is that floats are boats, not aircraft, and that a good kit boat designer would be the hot ticket for engineering the float. I got the impression from their Q & A that if there is demand, they will design it. Here ya go Bruce, give em' a call! Dan Montee +++ #14238 From: "Bruce A. Frank" Subject: Re: Stitch & Glue Floats Their stuff makes a wood float with a fiberglass overlay look like a viable idea! Bruce A. Frank +++ #14239 From: "Dan Montee" Subject: Re: Stitch & Glue Floats Bruce, FWIW, they distinguish the stitch and glue designs as being a true composite vs. plywood covered by glass. Composite being lighter and stronger. Dan Montee +++ #14241 From: Del Rawlins Subject: Re: Stitch & Glue Floats > http://www.bateau.com/index.html. These guys are successful boat > designers. Good site. I've had the plans for their "flat 11" skiff for a number of years, but got interested in the Bearhawk and never got around to it. At some point I may take a month or so off from bearhawking to build it, but since my canoes are more useful it isn't a priority. Been thinking of ordering plans for their "Indian River Skiff" since my brother and I have a perfectly good 15hp outboard preserved in a crate down in Cordova. Then I could trailer it down to the Anchor river and Bob and I could go steelhead fishing with it. Somebody kick me. *repeat after self* MUST BUILD BEARHAWK PARTS MUST BUILD BEARHAWK PARTS MUST BUILD BEARHAWK PARTS Anyway, I think stitch and glue would be the fastest way to go for homebuilt floats, the trick would just be keeping the weight down. I built a 13' stitch and glue flat bottomed canoe a few years ago, and spent exactly 2 weeks building the entire structure. The rest of the work (the gunwales, sanding, finishing) took a little longer but I would say I had no more than a month into it. The most time consuming part of the entire process was waiting for epoxy to cure before proceeding to the next step. It wasn't especially light but that was because I used the cheapest exterior plywood I could find (which was all that was available in Cordova without a special order). If you used a basket mold and had patterns for all the pieces, you could really crank them out in a hurry, and the building method is simple enough that even the Planter can figure it out. -- Del Rawlins +++ #14247 From: Ken Beanlands Subject: Re: Re: Homebuilt float If you're looking for the North Aire floats, Lake and Air is where I bought them from. Ken Beanlands B.Eng (Aerospace) +++ #14248 From: Ken Beanlands Subject: Re: Stitch & Glue Floats Glen-L might be another source for designing a lightweight wooden float kit. Ken Beanlands B.Eng (Aerospace) +++ #14251 From: "Bruce A. Frank" Subject: Re: Re: Homebuilt float Here is the Wag Aero Web Store listing of the North Aire Floats. http://store.wagaero.com/*ws4d-db-query-Show.ws4d?*ws4d-db-query-Show***GDD-CAD-251251254260251251-1412***-eProducts***-***shopping(directory)***.ws4d?shopping/results(S).html Be sure to past the whole URL rather than just clicking on it. If you cannot get there with this long address then go to the Wag Aero Store and type in the "Key Word" slot "floats". The plans are prices at $45....same as they were when I bought a set 8 years ago. Bruce A. Frank +++ #14259 From: "Russ Kaye" Subject: RE: Stitch & Glue Floats Or maybe if you like s&g try http://www.devlinboat.com/ Russ Kaye +++ #14271 From: John Dougherty Subject: Re: Re: Homebuilt float I have a set of plans for the Northaire floats. I have a freind that built a set. he did make them larger (he thinks to about 1660's) and they do perform very well on his homebuilt supercub. He owns a sheet metal shop and when he bent up the bulkheads and chines etc., he made two sets. I bought one set from him but have never used them as they would not be suitable for a Bearhawk. I suppose I should think about selling them..........John +++ #14286 From: "Brian Cox" Subject: RE: Re: Homebuilt float Check out www.full-lotus.com. They sell inflatable floats and have a 2700# version. I saw a pair for a plane similar to a Bearhawk that a chapter member had completed. He was cleaning out his hangar here in Colorado before flying his Arctic Fox up to Alaska. I had heard this fall on this group that some of the Alaska Bearhawkers had seen the plane. He just installed two front seats and left the back open for cargo. The floats could be deflated and folded, then fit in the back of the plane. Brian Cox, #478 +++ #14291 From: "Bruce A. Frank" Subject: RE: Re: Homebuilt float One of the cool things about Lotus Floats is being able to do exactly that, fold them up and throw them in the back. Knew a guy who would fly to AK with his plane always overloaded. He would ship the floats and install them when he got there so no drag or other problems traveling cross-country. The draw back was that they do not get off short. He always had to get up enough speed to lift one float (aileron roll) before he could leave the water. Bruce A. Frank +++ #14300 From: Ken Beanlands Subject: RE: Re: Homebuilt float OK, I absolutely LOVE these floats (except for the looks) You can run them up on a beach with no worry of damage. The balloon effect of the inflatable floats takes out a lot of the pounding on the airframe. There is no chance of having water leah into a compartment due to the possitive pressure in the cells. If a cell does leak, the other cells fill in the area of the deflated cll and away you go. You can run with half the cells gone in each half of the float (fore and aft). The flat bottom does not draft as much as well. The Rebel I've flown was equipped with these and was a joy to fly. Downsides are the non-traditional look of the floats and the lack of amphibs on the larger floats. I didn't realize that you get them in a 2700 size. Ken Beanlands B.Eng (Aerospace) +++ #14302 From: Tim Subject: Re: Re: Homebuilt float They're nice floats and the company took care of the problem with the zip on bottoms coming off (hard shell) my only concern is vandalism ie: some punk with a beach blade. 321Tim +++ #14305 From: Rob Sexmith Subject: STOL cuffed BeaverHawk STOL cuffs added to the de Havilland Beaver's NACA 4415 airfoil improved its powered slow flight angle of attack and short field performance. Similar STOL cuffs applied to Murphy Rebel are reported to do the same. How would STOL cuffs on a BearHawk affect it's performance. I know I am suggesting modifying perfection; but What If??? +++ #14308 From: Ken Beanlands Subject: Re: Re: Homebuilt float Heck you can do that with aluminum floats too, and they are a lot more difficult to field repair than the Full Lotus. Basically, a bicycle repair kit could fix most punctures. Ken Beanlands B.Eng (Aerospace) +++ #14314 From: Russ and Penny Erb Subject: RE: STOL cuffed BeaverHawk When this has come up before the general consensus was that the Bearhawk already has a slow enough stall speed that additional hi-lift devices would be of little use. Remember that leading edge devices increase lift by increasing the stall angle of attack. Depending on your landing gear geometry, that can be a problem. Remember that if the tail wheel touches first, the aircraft will immediately de-rotate and slam the main gear to the ground, and there's not a darn thing you can do about it. If the tail wheel touches while the main gear are still 5 feet or more in the air, you better have good, strong landing gear and a good seat cushion. OUCH! Accident report: "The Bearhawk with leading edge cuffs successfully landed with a ground roll of 10 feet. However, the landing gear is splayed, and the pilot is in the hospital with back injuries..." Likewise, the maximum takeoff AOA is the AOA in the 3-point attitude. If that AOA is already below the stall AOA, the cuffs won't improve your takeoff performance. They will add a small amount of drag and take away from the top end and cruise speed. All design elements are a compromise. Russ Erb +++ #14321 From: "Luc Morin" Subject: Re: Re: Homebuilt float The problem with float comparison is that you can never compare a design with an other if it is not on the same plane or almost on an identical other. WE where tree J-3 owner with two with an Continental C-85 and one with a C-90. My plane have EDO 1320 as I did mentionned earlier but my friend with the same engine had EDO 1400. My plane did out performed the other one by many second on take off. Butthe other one with a C-90 had EDO 1400 and he was outperforming me by a uge marging so... The best is always the same plane with different float for the rest the rigging, the prop, the engine wear and so one. For me and my comparable friend he sell the plant not being able to acheive good performance from is set up I did suspect a bad rebuild of the airframe after a ground loop when it was on wheel... +++ #14332 From: Rob Sexmith Subject: Re: Landing Last 15 feet Final - STOL cuffed BeaverHawk To better understand your response I need to understand your and the groups' responses to two stick and rudder piloting questions? 1) Landing, Over the fence 15 ft above the strip where are your eyes, what are doing/managing/looking for just before touchdown? 2) Multiple Choice -- Choose One. When landing a BearHawk (taildragger) I try to land a) Power On main wheels first landing b) Power On tail wheel first landing c) Power On three point d) Power Off main wheels first landing e) Power Off tail wheel first landing f) Power Off three point g) Who cares as long as my Brakes Hold Rob Sexmith +++ #14335 From: Budd Davisson Subject: Re: Re: Landing Last 15 feet Final - STOL cuffed BeaverHawk These aren't questions that can be answered as asked. It depends on the runway, the approaches and the conditions and what you're trying to do with that particular landing. I was going to try to answer the questions but got bogged down in the numbers of variations possible. You obviously are asking for a reason. Let's deal with the reason first and then get to the piloting questions. bd +++ #14340 From: Russ and Penny Erb Subject: RE: Re: Landing Last 15 feet Final - STOL cuffed BeaverHawk I can only answer that with respect to glider landings, since that's about all I've flown as PIC for the last several years and the only taildragger experience I have. 1) At 15 ft above the strip I'm still looking at the aimpoint because I've still got another 5 feet to go to the flare. After that I'm looking at the runway about 30 to 40 feet in front of me to judge the height for touchdown. Looking at the far end of the runway like some instructors say has never worked for me--too far away to judge. 2) d -- Power off--it's a glider! Main wheel (only one) first because gliders are happier landing that way. There's only a couple of degrees attitude difference between level and 2-point anyway. Landing at too high of a pitch angle breaks the main gear when it slams down. (In case you missed it, when the tail wheel is on the ground, you can pull all you want on the elevator and it's just going to squash the tailwheel--as the nose come down, each degree of rotation reduces the angle of attack on the wing and reduces the lift that much more--it's a divergent, uncontrolled motion all of the way until you smack the ground.) I doubt you're going to get a consensus on this--my experience has been some people prefer wheel landings, some prefer 3 point. Some aircraft are easier one way or the other. What's best is whatever you can do consistently and safely. Russ Erb +++ #14347 From: Rob Sexmith Subject: Re: Landing Last 15 feet Final - STOL cuffed BeaverHawk I agree many variables, many conditions, many techniques. My focus here is taildragger landing not on some 6000' runway; but at some 1000' or less farm strip etc. with a barb wire fence and drainage ditch awating me should I land long. If I land long (landing run increases as the square of the speed). Hit the fence -- (impact force increases as the square of the speed). Bad Landing Run - swerve- (centrifugal force of swerve increases as the square of the speed. ergo ground loop. Hence land slow. But slow landings are not necessarily the easiest. By now you can guess why I do not hang around the Long EZ group. I had read about STOL cuffs used by bush pilots and their landing techniques where there do not seem to be concerned with their tail wheel other than loosing it on some boulder -- hence they prefer wheel landing on STOL cuffs; yet Russ worries about tail first , de-rotate, pounding mains, breaking safety chains, fraying bungees, etc. for potential gear failure. So I re-read what Russ says below and tried to match it up with what I have read about bush pilots landing on gravel bars -- Then BAM!!!! it hit me. True Gravel Bar Bush planes have Tundra Tires. The dummy that I am failed to account for their increase in angle to compensate for the STOL cuff's increase in AOA. So at stall landing Bush planes could/should/would be landing on their mains as their planes are probably setup to have the tailwheel off the ground by 3in or so at landing geometry. So one question to Russ et all regarding STOL cuffs is: Assuming you are willing to give up top end speed for lower end slowness (for the reasons I stated above), How much would you need to increase the mains (tires, wheel, gear length in any combination) to add STOL cuffs and how much Slower would the BearHawk wing fly with them? Would adding Tundra tires be enough? ITEM Two Russ's image of tailwheel first with mains 5ft plus above the ground still make me thing about " landing, over the fence 15 ft above the strip" Let's start with just eyes upon landing, over the fence 15 ft above the strip. Where should they be? Forward, side down or some variation? I would answer 10 o'clock down? I then know my (depth perception) altitude and attitude for stick back- arrest, full stick back- land. I would know 10ft, 5ft, 3ft, 1ft, High Wing attitude for that magic mental trigger -- full stick back into the gut. I will defer my second question re: power on/off, wheel first, tail first landings until after the STOL Cuff and eyes upon landings are discussed. Rob Sexmith +++ #14350 From: Del Rawlins Subject: Re: Landing Last 15 feet Final - STOL cuffed BeaverHawk I assume by STOL cuffs you do not mean leading edge slats or anything that complicated. If you are talking about the leading edge cuffs sometimes added by Cessna drivers, don't bother. My understanding of the Bearhawk airfoil, is that it is a modified NACA 4412 (which is a common airfoil used in some Cessnas and other planes). Bob Barrows has already modified it to include the leading edge droop that is achieved by installing leading edge cuffs on Cessnas. So you don't have to do anything but build it to plans to achieve whatever benefits the leading edge droop provides. Somebody here correct me if I am wrong about this. For what it's worth, an A&P friend of mine related a story about some guys who had to ferry a Cessna with one damaged wing. They installed the wing off another airplane, which resulted in the airplane being ferried with one cuffed and one non cuffed wing. The pilot couldn't tell the difference according to the story. -- Del Rawlins +++ #14352 From: Budd Davisson Subject: Re: Re: Landing Last 15 feet Final - STOL cuffed BeaverHawk 'Guess it's my turn. First, 1000 feet isn't particularly short, even with the fence, although if it's rough, it'll feel short. I routinely land a Pitts Special in 1000 feet on smooth grass and I'm much more than fence high at the threshold. Any GA airplane, even a 172 and particularly a 182 can handle that fine. There are a couple of factors that have to be taken into account when landing short and one of the most important is that you see the point you're going to use to touchdown on almost until you hit it. And then you hit that point every time Period. Being super slow doesn't help you if your nose is so high you can't accurately see the touch down point and you leave too much runway behind you. Helio Couriers can fly incredibly slow, but at max AOA, you can't see over the nose so they have to give up speed for visibility. As Russ said, most of the high lift devices like cuffs and VG's make the wing hang on longer, but you run the risk of giving up visibility or speed, they can't have both. The amount of this effect depends very much on the airplane. It's generally better to get slow speed with wing area, aspect ratio or, better yet, effective flaps, so your nose is within an acceptable range of angles. At the same time, you want to sit as high in the airplane as physically possible for super short approaches to get your eyes high over the nose. The point you're going to touchdown on isn't necessarily the threshold, but some place far enough past the threshold that you aren't dangerously low over the threshold. Maybe 100 feet past it. For the same reason, you don't drag it in super slow, Vso plus .5 knot, etc with lots of power. There's an old bush saying that makes terrific sense "It's much better to roll off the other end at 5 mph than land short." If you're landing on 500 feet, it's probably wise to shoot for the threshold, otherwise play it safe and have a few feet over the threshold. The smart money flies a de-accellerating approach with a specific speed in mind to hit just short of the threshold. It doesn't have to be so close to stall that the back side of a gust will drop you out of the air. It just has to be slow enough that the airplane is on the backside of the curve with high enough drag that it is really responsive to power for glide slope control. Again depending on the airplane this could be anywhere from 8-12% over stall. As for how you touchdown, it again depends on the airplane. If you want to land short, you need braking so you can't have even the slightest bounce. You want down and you want to stay down. If you nail the tailwheel on too aggressively, you'll bounce the mains and get no braking. If you do a traditional wheel landing, you'll be too far above stall and have too much energy to get rid of. Some of you bush guys can chime in here, but what is often mistaken for a wheel landing is actually a near three-point but the tail is raised just as it touches to put the airplane on the mains and nails it solidly to the ground. This works well with tundra tires that love to rebound and gives immediate braking. Personally, I prefer a well managed three-point with both the power and the speed bleeding off within 5-10 feet of the ground so I arrive on the deck with minimum energy, just enough to get the tail down in the abbreviated flair. The goal is to touchdown with no bounce and minimum speed exactly where you want it to and that comes down to pilot technique more than airplane capabilities. Only the serious bush guys fly their airplanes well enough that they are getting maximum performance out ot them. The rest of us are just approximating. The bottom line is that if the runway is so short that you need everything a Bearhawk or a Super Cub has to give, most of us probably shouldn't be landing there in the first place. Them's my thoughts. bd +++ #14358 From: "Tim Anderson" Subject: RE: Re: Homebuilt float I have LOTUS for my Kitfox. I flew them for one summer up in fairbanks. Worked great. They do not have a keel on the bottom so if one gets cross-wize, one would be basically water skiing. I never had a problem but the possibility exists. I had a guy make water rudders, he had a wag-aero 2+2 and had done the same thing. Tim Anderson +++ #14371 From: Budd Davisson Subject: Re: modified 4412 Good info, Lee. Gust factors at really slow speeds can be major factors. When we start talking landing speeds in the 40 mph bracket, a wimpy little 5 knot gust isn't so wimpy. Since it is such a big percentage of the airplane's speed, at the moment of onset (positive or negative) it can have a real sheer effect and when you're at minimum speed, trying to get down over the trees, that definitely isn't good. Also, I think I should clarify what it is that Bob "modified" about the 4412 and it ain't much. We talked about it in some detail when we were together just before Christmas. The 4412 has a slight "flat" spot in the top surface toward the front of the airfoil and all Bob did was smooth out that curve. He didn't droop the snoot or go for a changed stagnation point or anything. He says he doubts seriously if you can tell the difference in flight. So, we should consider this pretty much a stock airfoil. I asked him why he used a Ribblet on the BH Too and he said, "Oh, I don't know. I just thought I'd try one." That's our Bob. bd +++ #14407 From: "rodsmith52" Subject: Re: modified 4412 Is that what Bob said? If so I am really confused. I had a full size copy of Bob's modified airfoil printed and then plotted the unmodified 4412 over it. Bob's airfoil was drooped about a 1/4" at the nose compared to the unmodified. I got talking to Harry Ribblett about it. He was curious what Bob did with it. I sent him a copy. Harry said there was a right and a wrong way to add leading edge droop to an airfoil and Bob had done it the right way. The resultant airfoil was very similar to Harry's 30 series airfoils. +++ #14489 From: "Bruce A. Frank" Subject: Slow Flight We got into some discussion about leading changes to improve slow flight and the dangers thereof, but I'd like to pursue the line of speculation a bit further. What are the impact of stall fences and drooped tips vs. Hoerner tips. We also got into some discussion of vortex generators. I understand the worries about gusts at such low speed, but if the wing airflow is energized with vortex generators and with a tip that controls the wing tip vortices can there be safe flight, safe stalls at 30 mph with the Bearhawk wing? With the Piper (USA35B) wing? The first question I'd like to explore is a Hoerner tip compared to, say, a Demers (droop) tip for controlling slow speed flight? Bruce A. Frank +++ #14494 From: Del Rawlins Subject: Re: Slow Flight > We got into some discussion about leading changes to improve slow > flight and the dangers thereof, but I'd like to pursue the line of > speculation a bit further. What are the impact of stall fences and > drooped tips vs. Hoerner tips. We also got into some discussion of > vortex generators. I recently had a discussion with my brother on vortex generators. My understanding of them, is that they are more often used to correct for some undesirable characteristic, and that they are of limited usefulness in most light aircraft applications. The exact quote of the IA that helped us with the Citabria was "just learn to fly the airplane" when I asked him about whether they were worth installing. But in my discussion with my brother, he explained his reason for wanting them, and it all has to do with float operations. Basically the VGs help a floatplane get up on step more quickly, which requires a high angle of attack at a low airspeed. The faster you can get on step, the faster you can get off the water. > The first question I'd like to explore is a Hoerner tip compared to, > say, a Demers (droop) tip for controlling slow speed flight? In the basic aerodynamics class I took last fall it was explained that the function of the drooped tip is to effectively create a longer wingspan, which keeps the tip vortices from interfering with the ailerons, thereby reducing adverse aileron yaw. -- Del Rawlins +++ #14964 From: "bearhawk484" Subject: Updating plans to reflect enginering changes Hey guy's.I am plans owner #484 and have been making notes on my plans reflecting recent changes (non- mandatory).In the Oct. 2002 Beartracks newsletter suggested changes item #4 doubling centre root end rib. Does this refer to centre rib #1 only .032? Item #3 main spar front TOP cap strip to extend to front spar plate root end. How can only the TOP strip be extended? If this is done it seems to me the .032 attach angles for the nose ribs will be at an angle ( out top to bottom .125). Should the BOTTOM strip be lengthened as well? The wing load test (same newsletter)refers to small distortion at centre BUTT rib near rear spar, nowhere on the plans can I find mention of a BUTT rib detail. To me the short ribs aft of the main fuel tank #3 are these BUTT ribs,is this correct? Having read the flight reports on the Bearhawk I see that the trim seems to be to sensitve.Has there been any thought of downsizing the length of the trim tab? Shortening the tab to the first T25 outboard of the trim linkage will leave a surface 13.5"x5" long on each stab, should be plenty,less weight? Thats whats on my mind. Your thoughts matter. THANKS R Michael Mellor #484 +++ #14978 From: Budd Davisson Subject: Re: Updating plans to reflect enginering changes The butt ribs referred to are the .032 center root ribs. There has been some talk about shortening the trim tabs, which I believe Bob has done but it doesn't seem to make much difference. A longer ratio would work better. At least one airplane is going together with a walking beam in the aft end of the trim system to change the ratio. The nose rib attach angle would have to be spaced out and the back edge of the rib trimmed accordingly, although there is probably nothing wrong with extending the bottom cap strip too, although it is unnecessary and adds weight. bd +++ #15000 From: Russ and Penny Erb Subject: RE: Updating plans to reflect enginering changes The top capstrip is lengthened to prevent buckling. It was strong enough for compression before, and the bottom capstrip I suspect is in compression also but not as much, so extending it would just add weight. You will need to space the rib out. I've installed a trim system that includes a jackscrew between the wheel and a bellcrank. My concern is that the mechanical advantage will now be so high that I'll be spinning the trim wheel like mad. I think I put the drawings up in the files area. Russ Erb +++ #15667 From: "zipppydoggg" Subject: pounds per G I was just reviewing bd's Hawk Talk newsletter (excellent by the way) and noted that the article on the wing static test used 6,000 pounds. This load was shown to be equivilent to 5.7G, which works out to be just over 1,000 pounds per G. From this I would conclude that the weight of the wings was not considered in this test, after all, the weight of the wings and fuel is carried by the wing itself. Is this correct? I suppose that the G load quoted is based on a maximum gross weight, less wing weight. I'm just beginning the effort to put about 100 pounds more engine weight than is recommended, as well as the other compications (longer gear, more fuel, etc.)that come with a bigger engine. I starting the research. I was supposing that gross weight (in general) is based on 5 things, 1-landing gear strength, 2- fuselage, floor strength, 3- wheel, tire and, brake strength, 4- takeoff and climb performance and 5- wing and strut strength (G capacity). Does this sound about right? Just to keep and Apples for Apples comparison, I suppose that one should know the wing weights seperate from the full up aircraft weight. Rob "engine on the truck heading my way" Gaddy BH401 +++ #15668 From: "Matt Prather" Subject: Re: pounds per G > I was supposing that gross weight (in general) is based on 5 things, In addition to takeoff and climb, I would include stall speed (which drives approach speed) and landing rollout length. On a Bearhawk, the wing loading may be low enough that they aren't an issue. +++ #16480 From: Budd Davisson Subject: Re: Floats We're still collecting information on floats to help customers and, since I'm from Nebraska/Oklahoma where we don't worry too much about floats, I'm going to depend on some of your expertise to help answer the following questions: We've been told EDO made some 2750 straights (2690's as amphibs) that were electric retracts for C-180s that were too small so became unpopular. The question is, is this a correct fact and are they harder to find than most floats? Also, what price to they run if found? We've also been told there is a Czech company cloning EDO floats. Does anyone know anything about this? Thanks, bd +++ #16481 From: Budd Davisson Subject: Re: Re: PS PS question: What is the consequence of over floating the airplane other than carrying weight you don't necessarily need? I'm thinking about the Murphy 3000's (or is it Aerocomp) and our 2700 pound gross on floats. bd +++ #16482 From: "Mike Carriere" Subject: Re: Re: Floats There are a lot of options for the BH on floats. Edo made the older 2425 (flat tops) which fit the stinsons and even some older C-180's The C-180 was most commonly found on a pair of Edo 2870's which are a round top straight float. I believe the amphib you are asking about is the Edo 2790 which looks like the 2870 with wheels and a fair amount of them were installed on C-180's and the Maules. When the C-185 started to get popular (mid to late 60's) edo went to the 2960 and 3430's. I have a chart of actual displacement for each model including CAP's and Whipline and PK. BH #469 is sitting on CAP 3000's and they look too large for it. I believe the 2870's will work but we have some homebuilders out of Quebec that make a 2700 lb displacement float (flat top looks like a PK) for about $6000 US excellent workmanship. Recently bought a set of 2000's (Edo style) and they are great. Aqua 2440s and Bauman 2750's would be a great float as well. As I said, a lot of options for the BH but look for a displacement form 2500 lbs to 2700lbs Mike Carriere +++ #16512 From: Ken Beanlands Subject: Re: Re: Floats We actually had a set of 2790's for the 180 but the gear was missing. Dad had the idea of converting them back to strait floats but it was not to be (too much red tape involved in sticking on a couple of patches). He was able to TRADE them into a set of 2960. One thing I would suggest is to use strait floats if at all possible. Amphibs will add about 300-350 lbs to the empty weight (especially with EDO amphibs). That would severely impact the useful load. Take a typical BH with a 1400 empty and add 600 lbs and you're up to about 2000 lbs. Add in 325 lbs for fuel and you have about 375 left. As most bush operators will tell you, a C-180 with amphibs is a great 2-place machine ;-) Ken Beanlands B.Eng (Aerospace) +++ #16526 From: Budd Davisson Subject: Re: Floats FYI - I just got in contact with the Czech float company that is building Zenair floats and cloning EDO's and this looks promising. Right now the biggest float they make is a 2444. A bit small. They estimate a 2700 amphib would weight 500 pounds a set and straights about half that. We're going to get together at SnF. Just thought you'd like to know. bd +++ #16527 From: Budd Davisson Subject: Re: Lower Flying wires Here's my thoughts on wires: Go with the Brunton's wires top and bottom, round on the bottom where they could be damaged, streamlined on the top where they can be seen. Has anyone checked what the actual diameter of the Brunton's round 1/4" wire? It is probably drawn down and smaller than 1/4". And as for the Reynolds number: it's one of those delicious dimensionless coefficients that intuitively give a feeling of efficiency but in reality are hard to define so they make sense in real life terms, as in "Ah, who gives a damn, the Rn is down around 200,000. When it gets up to around three million let me know and I'll start worrying about it." Engineers love to talk that way. It's as close as we get to talking dirty (well...not really). bd +++ #16545 From: "Mike Carriere" Subject: Re: Floats > I remember seeing a ad in General Aviation News from a company here > in Wisconsin... Thats probably Baumann Floats, New Richmond, Wi. 715 246 9352 They have a model BF2750 ampib and straight. Mike Carriere #463 +++ #16704 From: "Bruce A. Frank" Subject: Decisions, Decisions Corky Scott sent some pictures of his airframe, Christavia MK4, and I noticed something that I'd like to incorporate into my plane. I'd like opinions on the feasibility of this mod. On the Piper (TriPacer fuselage) airframe the lift strut attachment point is right (roughly) in the middle of the door. I noticed on Corky's Christavia that the attach point is in line with the front post of the door frame. This keeps the struts completely out of the way for entry and exit. Remember this plane uses two struts (rather that a single strut like the Bearhawk) and jury struts. Moving the attach point forward under the door front post appears to me to not be a significant modification. Since my intention is to eventually put this plane on floats I have designed swing up doors and I just hit me that moving the strut attachment point to the longeron area below the REAR post of the door would allow easy movement forward on the floats. Opinions please! Bruce A. Frank +++ #16705 From: John Dougherty Subject: Re: Decisions, Decisions I talked to Bob about this same thing a couple years ago and he said there would be no problem doing that except, you would have more difficulty routing the cable that goes up the strut. Apparently he originally had the strut on his at that position but moved it to make cable routing easier......Jack +++ #16706 From: Budd Davisson Subject: Re: Decisions, Decisions You'd have to move the carry-through structure with it, change the angle of the attach fittings in the wing and then worry (just a little) about the asymmetric loads in the spar and drag/anti-drag trusses. bd +++ #16708 From: "Bruce A. Frank" Subject: Re: Decisions, Decisions Well, on mine anyway (different from the Bearhawk) all control cables go from the cabin into the wing root. Bruce A. Frank +++ #16709 From: "Bruce A. Frank" Subject: Re: Decisions, Decisions Angle of lift strut attach fittings in the wings is a piece of cake because I am using Heim type extra capacity rod ends. Rather than drag/anti-drag wires the wings are assembled with what are called "W" braces configured with 1" square aluminum tube. Now as for the asymmetrical loads...that is a significant point of this discussion. The Christavia wing is essentially a duplicate of the Piper wing (but wood spars rather than my aluminum ones). My wing spars have doublers from the fuselage attach points out past the lift strut attach points. My compression struts are sections of rear spar material (with routed lightning holes in the web area) attached to the spars with aluminum angle brackets (the point is to create a ridged "box" structure to handle the loads of 10' Fowler flaps, with reflexing, and extended ailerons on each wing...Piper OEM style wings tend to flex and distort which sometimes causes reverse control problems when flying slowly using stop to stop aileron inputs and high bank angles. Bruce A. Frank +++ #16710 From: "Bruce A. Frank" Subject: Re: Decisions, Decisions I left out one point, the carry through structure. If I go to the forward attach point, under the door post, I have a near duplicate of the OEM cross member structure with additional support from seat support diagonals. This point is where the front of the gear leg pivot is located in the TriPacer-to-Pacer conversions. If I move the attachment bracket to the rear door post position there is heavy cross member support with additional vertical bracing (added when I widened my cabin at the shoulders) and, again, part of the seat support structure diagonals. Bruce A. Frank +++ #16949 From: "Bob Andrews" Subject: Montana Float Company (MFC) I'm the MFC east coast distributer, and had the opportunity to visit with Mr. Bob Barrows a few days ago under his wing at Sun & Fun. He indicated that Bearhawk builders have shown interest in floating their aircraft. MFC is coming out with a float (based on the 3500 design) in the 2600 - 2800 size. Currently the plan is to provide finished floats and kits. Mr. Barrows indicated that there is considerable interest by the builders to construct from plans using raw materials. Hence, we are considering a "Parts & Plans" product. Top deck, side skins, bulkheads, etc. are built from plans using 6061- T6 flat stock, and landing gear, special extrusion type parts, etc. are purchased as needed during construction. As a plans builder of a 2+2 and kit builder of a set of MFC 2200 amphibs, I personally whould have liked to have had this "Plans & Parts" option (it was hard to drop 14k on the amphib kit ... piece-meal funding it would have been nice). I've launched a poll that will close at the end of the month ... please vote if you plan to splash your Bearhawk. Thanks, Bob Andrews +++ #16953 From: "Bruce A. Frank" Subject: Re: [Bearhawk] -7 degrees flaps > Why does Maule include -7 degrees flaps on their aircraft, and would > that benefit us on the BH? This has been a topic of discussion. Reflexing the flaps should improve cruse speed. Pat, did you set yours up with reflexed flaps? Bruce A. Frank +++ #17047 From: pfflyerz@c... Subject: Re: -7 degrees flaps > Pat, did you set yours up with reflexed flaps? No, still haven't gotten around to messing with that yet. I've been working on my strut fairings. Finally got them painted, but haven't installed them yet. I've discovered that I have absolutely no patience left for building, #232 sucked me dry. Pat Fagan +++ #17195 From: Doug Knight Subject: Bearhawk wet wing I have been working on this modifacation and should have it in by mid next week. Total Fuel 65 gallons, 32.5 gallons for those of you who can't divide. Weight savings about #30 off of the airframe. Doug +++ #17200 From: "John Haugen" Subject: Re: Bearhawk wet wing Thank you, thank you, thank you! I am a big fan of wet wings, and was dreaming of a way to incorporate it on the BH (tough because I haven't seen a BH wing). Is this removable with screws, or fixed with rivets? My thoughts were to have a tank shop (I don't weld alum) weld one for me, avoiding the possibility of leaks. Also how do you intend to prime your tank, if at all? JH +++ #17203 From: "doug" Subject: Re: Bearhawk wet wing Tank is removabale from the top with screws. Internal priming is only alodine, that's all that's required. While I'm a certified welder I saw no challenge in welding up fuel tanks. I've done thousands of gallons of fuel/hyd/h2o in the marine industry and wanted a change. There's even room for more fuel if you can plan on it early on. this brain fart came after the spars where built. Doug +++ #17205 From: Budd Davisson Subject: Re: Re: Bearhawk wet wing You're going to have to describe this because we may have a semantical problem here. The definition I've always heard for a wet wing means there is no tank. The wing itself is a sealed tank. So, what is it you're doing exactly? bd +++ #17208 From: "doug" Subject: Re: Bearhawk wet wing Rod, as in what kinda details are you looking for? I'll share a little but I'm not going to give away the store. Last time it did that was with the "BOB's vented fuel caps" I sorta got NAFTAed. I'm still sitting on a few that I'd like to get rid of. I could build you an AMERICAN wings/wet fuel cells but that is not what you are probably looking for, so please clarify your questions and I'll answer what I'm willing to share at the moment. In short, skin top and bottom wet, tank bolts in from top, no hat section problem any more, spar cap stiffened in another manner. While this tankage may pose an added cost right here in the beginning, the bennifits will be rewarded in the future. I get an added margin of 1 hour and #30 extra to play with. Imagine using the Bobs arangement at 76 gal (2 mains & 2 aux) with a hardware penility of #52 (of mains and aux). Doug +++ #17211 From: "doug" Subject: Re: Bearhawk wet wing Then, you and I are going to agree to disagree. A tank bolts into an enclosure, a wet wing uses skin as part of the fuel surfaces. How about an RV or Piper? A wet wing also has stucture for the wing. A tank has none and fulls a void and is along for the ride. Semantics, yes. Doug +++ #17212 From: Benton Holzwarth Subject: re: Bearhawk wet wing Ah, I get it. it's still a tank, but rather than nestling into a bay in the wing and then being covered with wing skins above and below, the top and bottom surfaces of your tank form the wing surfaces as well. I think what you're doing is still different than, say, an RV's wet wing, where (am I mistaken) they really do, literally, seal a couple bays of the wing, and fill it with fuel -- no separately constructed, removable tank. So, in either of those -- the Bearhawk or the RV, those wing skins are stressed wing members. Your tank is rigid enough and mounted firmly enough to take up those loads? Benton +++ #17213 From: "Bruce A. Frank" Subject: Re: Re: Bearhawk wet wing Wait, before this gets out of hand, let me describe what I see. I see a tank that will be inserted into the wing. The top of the tank becomes the top of the wing and the bottom of the tank becomes the bottom of the wing. The top of the tank, and I am assuming this, will have a flange that is screwed down to the rim around the wing opening. The tank, though inserted, will have some structural (though maybe minor) function in the wing. I am also assuming that the top and bottom of the tank will be riveted to the sides and ribs/baffles in the tank. I have sent an email to Doug asking for more details as I have a similar concept for my project. However Doug responds, I would like to see it all here in the group. Dough, please do not be conservative in how much you write. I for one would like an extensive word picture along with some additional photographs. This group is all about sharing and helping each other. You appear to have a unique concept of this tank and I am here to learn. Bruce A. Frank +++ #17217 From: Budd Davisson Subject: Re: Re: Bearhawk wet wing As our loading tests showed, the top of the wing skin in the tank bay area is a primary piece of structure and is where the wing twist shows up first. Just making it stiff or heavy isn't enough. The attaching system for the tank has to allow for smooth continuity of stress from the rear to the front spars and into the skins ahead of he spar. Not a difficult task, but something that has to be considered. I don't think this is considered a wet wing but a "structural" tank. Either way it can be made to work as long as the engineering concerns are worked out. bd +++ #17220 From: Bruce Gagne Subject: Re: Re: Re: Bearhawk wet wing Just to clarify the semantics in my own pea-brain... It's my understanding (no need to ask for corrections if I'm wrong; they'll come!) that a "wet wing" set up, such as Mooney's is as already described. That being simply a chunk of the wing sealed up and given all the proper plumbing and it's a fuel tank. The set up that Doug described seems like the method used by Piper (all my experience is in PA-28/38, so I don't claim this to be universal to all PAs) is a separately constructed tank that's set in place with 10 gazilion screws that'll get rusty over time. Once installed, the tank then is a load bearing part of the wing. This set up, I believe is referred to as an "integral tank" is it not? Again, semantics, but it is two different arrangements and building methods. BruceG +++ #17221 From: "Bruce A. Frank" Subject: Re: Re: Bearhawk wet wing A tank that actually has to handle structural loads is an exorcise in engineering. One of the most common problems with the F.Atlee Dodge Piper replacement tanks is that if they are not somewhat isolated from the wing's normal flexing they develop seam leaks. I had at one time contemplated a welded tank for my Piper wings that incorporated the through tank brace as part of the structure of the tank. After talking to several experienced aeronautical engineers and a bunch of AIs and A&Ps I decided it prudent to abandon that idea. Bruce A. Frank +++ #17222 From: Budd Davisson Subject: Re: Re: Bearhawk wet wing To do this in a stressed skin wing requires some structural subtitles be taken care of at the interface of the tank to the wing structure, but it can be done. The primary concern is that the tank not introduce some discontinuities in stress flow, e.g. unintentionally make a piece of the spar cap stronger locally which then introduces a sharpish discontinuity at the edge of the tank in the spar cap. If all the possibilities are considered it can be done, but it does take some engineering to make sure the structural balance isn't upset somewhere. bd +++ #17225 From: Budd Davisson Subject: Re: Bearhawk wet wing Conceptually, a true "wet" wing is a great idea but from a practical point of view it's a real pain in the butt. It's hard to construct because everything has to be put together wet with sealer and then there is the constant specter of leaks developing, which almost always happens. A bolt-in, integral tank, like Doug is proposing has none of those problems but does require a little engineering finesse, as I mentioned. It's a much easier solution. To be conservative, however, I'd want to proof load a wing with that configuration. There is, however, a reason so many airplanes use welded tanks or bladders: it's the simplest of all solutions and doesn't introduce any structural complication but it does increase the parts count considerably and doesn't maximize the fuel load. bd +++ #17230 From: pfflyerz@c... Subject: Re: Bearhawk wet wing This has been a very interesting discussion. I believe I finally understand all the different posibilities. What I don't see is, in an integral tank installation, where is the great weight savings. You still have a bottom skin, and, so I assume hat stiffeners. You save the weight of a top skin, but the mounting flange must weigh at least as much as the saved top hat stiffeners. That leaves the only remaining savings to be the straps holding the tank in. I can't see any of that adding up to 30#. What am I missing? Pat Fagan +++ #17237 From: 321Tim Subject: Re: Bearhawk wet wing I remember Ray Semple commenting on his Davis that he originally built a wet wing for prior to building/installing welded fuel tanks, like the Bearhawk.....He changed from wet to wing tanks due to a couple of PRC leaks....Ray commented that he found it difficult to get all hand made parts (vs Kit) to the same close tolerances required for a nice tight wet wing. 321Tim +++ #17242 From: "doug" Subject: Re: Bearhawk wet wing Just the fuel bay panel is 032. If I had planned on this mod sooner I would have incorperated the nose sectionas well, like the RV's. the bueaty of this system is leaks are fixed on the bench. Short on time I'll sound in on more later. Doug +++ #17253 From: Benton Holzwarth Subject: re: Wet wing Another thought -- with this arrangement, any liquids at the fill port either go inside the tank, or outside the wing. There's no 'in between.' No 'scupper's to sort out. One more plus for Doug's idea. Benton +++ #17536 From: Budd Davisson Subject: Re: FLOATS TO BE AVAILABLE FROM MONTANA Now that you've opened the float subject again, I'll share this with you. We've been in conversation with Montana Floats and they've agreed to come up with floats for the Bearhawk. They are planning on offering the following: -Plans only -Plans and parts -Pre-drilled kits -Pre-drilled with tougher assemblies finished (on amphibs) -Finished and ready to float. They will offer both amphibs and straights, although they say that most of their business is in amphibs. They are working to a gross weight of 2700 pounds. After looking at their products I can honestly say that building a float from scratch would be tougher than building a BH wing by a fair margin. Not something for the faint of heart, but the plans will be available for any and all masochists. They gave me no time line, but it sounded as if it would be this year. You can go on their website (http://www.montanafloat.com/) or call them at 406-293-9026. Ask for Keith, although anyone who answers the phone can probably help. AviPro has nothing to do with this project other than helping get them fired up enough to do it. They will market them direct so don't ask us anything about them because we don't know diddly about floats. 'Thought you'd all like to know about this. bd +++ #17538 From: Ken Beanlands Subject: Re: Re: FLOATS TO BE AVAILABLE FROM MONTANA I know, I know, you asked us not to ask any questions, but one does pop to mind that your engienering curiosity probably asked them. What are they made out of; 2024 or 6061? The problem with a lot of teh float kits is the use of 6061. Sure, it doeas a little better in the corosion protection, but the softer nature of the material makes for lots of dents and dings. Floats take a lot pf punishment from people walking on them, sitting on a beach or slipway or tied to a dock. I've noticed that the Murphy floats (in fact, nearly all their products) use 6061. Most of the comercial float manufacturers (Edo, wipline, CAP, etc) use 2024. Obviously, if you went the masocistic plans-only route, then this would not be a problem, just sub 2024 for 6061. BTW, their float prices seem to be very reasonable. $9,000 for a good float kit is quite good. Ken Beanlands B.Eng (Aerospace) +++ #17539 From: Del Rawlins Subject: Re: FLOATS TO BE AVAILABLE FROM MONTANA > We've been in conversation with Montana Floats and they've agreed to > come up with floats for the Bearhawk. Thanks for the update. I reached the same conclusion about building floats from aluminum a few years ago after viewing several EDOs in various states of disassembly. If they actually offer a plans-only option, that will give us a proven hull shape of known displacement that can be reverse-engineered for composite, which I'd rather have anyway. I'll have to run it by my engineering staff *g*, but I think that using light birch ply with stitch and glue construction in a basket mold, accurate floats could be built quickly. This is a proven boat building method which produces strong, light hulls in a hurry. And if I have to do a field repair, the epoxy and glass can be flown in to me a lot easier than an air compressor to run my riveting/drilling tools. -- Del Rawlins +++ #17542 From: Budd Davisson Subject: Re: Float questions You failed the first test: you asked a question. Here's the answer: I don't know what they are using. I do know part of the reason for 6061 in a lot of kit products is that it's so much cheaper, but I doubt if they are using it. We considered it for cowlings and stuff but decided to go with the tougher material. As for price, I don't know that either. They were talking $15-16K for amphib floats and straights a little more than half that, so $9K sounds about right. E-mail them. I underscore what I said before: I don't know squat about floats. bd +++ #17543 From: Budd Davisson Subject: Re: Float questions REVISION I just re-read what I wrote and wanted to clarify something: the prices I quoted below were for their bottom line kit, not completed floats. The completed floats were going to be about twice that or $25-$30K for amphibs with all the bells and whistles (electric/hydralic gear, warning lights, mounting structure, etc). Again, straights would be about half that. bd +++ #17544 From: Ken Beanlands Subject: Re: Re: FLOATS TO BE AVAILABLE FROM MONTANA Heck, if you're going to do that, then just head down to the local seaplane base with a LARGE roll of paper, an adjustable T, a tape measure and start tracing. Ideally, look for a set of Wipline 3000's or maybe 2350's. By tracing out the flat skins, you'll have the first big design information for the stitch and glue process. Getting the skin patterns is typically the hardest part about stitch and glue design. You will need at least 8 formers to get 7 watertight compartments. use the adjustable T-square and ruler to get the shape of the formers. I know, sounds simple. but there is still a lot of design work to come up with the keel and chine designs, attach point design, etc. Ken Beanlands B.Eng (Aerospace) +++ #17545 From: Ken Beanlands Subject: Re: Re: FLOATS TO BE AVAILABLE FROM MONTANA Oh yeah, one other thing, you'll generally find a can of bodyfiller in the back of most floatplanes to take care of those eventual holes in the floats. Very simple field repair and it works well. The permanent patch after the fact becomes a little harder to do as you need to remove all the bodyfiller first. Ken Beanlands B.Eng (Aerospace) +++ #17890 From: pfflyerz@c... Subject: what the... where's the...S..T...no...%#!!!#&@*@%$#!... Two helpful hints for all you builders out there 1) install a parking brake 2) use the GD thing! I was on my way to an EAA chapter meeting Tuesday night where I was supposed to be the guest speaker, talking about building the Bearhawk. I planned to fly the plane up for show and tell. After pushing it up the little rise out of the hanger I went to move my truck. When I looked back, the airplane wasn't where I had left it. It had rolled back into the corner of the hanger, ruining the right elevator. I now have complete confidence in my welds. Obvious damage was limited to a slight buckling of the last tail rib. The elevator spar was tourqed, but no welds broke. Yesterday I replaced the spar tube and welded everything back together. Today I covered it. Isn't scratch building grand! BD, I still intend to make it on the 19th. Cal, Tahoe is out, though for reasons beyond this goof. For any one else, I hope to be at Watsonville on Fri. and Sat. Pat "bonehead" Fagan +++ #17895 From: Benton Holzwarth Subject: re: What the... >> 1) install a parking brake >> 2) use the GD thing! Chocks also are effective. Maybe not as convenient, but easy to retrofit, and don't have the nasty habit of becoming engaged (unbeknownst to you) while in flight. Either scheme requires part two, to be effective. A friend at work had been lamenting to me the time and cost to cover the landing gear pivot A/D on his Cutlass. He was looking at substantially more cost and time than Pat's effort cost him. (By a couple orders of magnitude on the $ dimension!) I'd said at the time that if I were to bend an LG on mine, I was free to make another, either just like the old one, or beefed up some. I forwarded your note to him and a couple RV builders here with an emphasis on the 'Yesterday I welded it up, and today I covered it.' So, you didn't mention the hangar fared. Does that mean you had to 'put it down?' Benton +++ #17899 From: "handainc" Subject: Re: what the... where's the...S..T...no...%#!!!#&@*@%$#!... My "original" Pacer has that type of friction lock emergency brake, and I have been totally unable to get it to work and many hours of fiddling with it. I would recommend something more positive, like the unit on later Tri-Pacers ( but that would be more weight). Any suggestions on getting my emergency brake to work would be appreciated. Someone, somewhere, (everything I do on the internet sort of runs together) I saw a post about creating an emergency brake on your plane by installing a friction tab on the master cylinder shafts to hold them after you depress the brake and pull a cable connection to lift the tabs into bind with the shaft. Might be an easy after thought with no major change to the craft. +++ #17904 From: "Garry Butler"