+++ #1013 Subject: Re: wing strut fittings From: Rod Smith > Looks like I will need a piece of 1 1/2 square 2024 T-3,4 aluminum. > All I have been able to find is 6061 T-6. Does anyone know where to > find the 2024 or will the 6061 work? This is available from Dillsburg in PA. Quite expensive but you would not want to substitute 6061. +++ #2588 From: Rod Smith Subject: Re: Status on strut material? --- In bearhawk@egroups.com, Russ Erb erbman@c... wrote: > For Mike Meador: Do you currently have strut material in stock? If > not, what are the plans for the next mill run? Mike will of course have more up to date information. Six weeks ago I inquired about the strut material. At that time Bob had just received his second mill run of struts, so he should have them in stock. +++ #2589 From: Mike Meador Subject: Re: [Bearhawk] Status on strut material? We have STACKS of strut material currently in stock. I picked it up last month. +++ #3615 From: Rod Smith Subject: Re: 023 Update & Budd's Bearhawk Fittings --- "William & Delinda Johnson" wjohnson@f... wrote: > I highly recommend purchasing the strut end fittings from George > Jenson (715.327.5514). To save time, I purchased and the quality is > very good. $145 P.P. USA. Here are some pictures. I thought these were quite easy to make (if you have access to a vertical mill) and I am definitely an amateur machinist. Looking through my builders log, I spent 8.3 hours on them. Could do a second set much faster. One concern I had was how to blindly drill the attachment holes through the strut material accurately enough to match the fitting holes. Consequently I drilled the furthest out attachment hole undersize. I will drill the corresponding hole through the spar material and bolt it, align the fitting, and then drill the 3 remaining 3/16 attach holes through the spar and fitting at the same time. Material cost was $42 dollars at Dillsburg, the only place I have seen it listed. +++ #3616 From: Bruce A. Frank Subject: Re: [Bearhawk] Re: 023 Update & Budd's Bearhawk Fittings Why not leave the fittings un-drilled then drill the strut and fitting assembled? Once the first hole is drilled, a bolt can be inserted to hold it all together for the subsequent holes with much lower likelihood of ovaled holes. +++ #3619 From: Subject: Re: [Bearhawk] Re: 023 Update & Budd's Bearhawk Fittings I spoke with Bob Barrows on the phone the other day and asked him how he managed to drill through the strut material and hit the holes in the strut fittings. I had been wondering how to accomplish that also. I am always amazed at how simple things are when Bob explains how he does things. He cut his strut material to length, then squashed the ends to the 1.5 inch dimension. He then clamped the fitting to the OUTSIDE of the strut and drilled through the fitting and one side of the strut. Unclamp the fitting, slide it inside the strut and drill through the whole thing. Simple. To do the other fitting, bolt the first one to the outside of the strut and then bolt it to the wing or fuselage. Bolt the other fitting to wing/fuselage, then clamp the fitting to the outside of the strut. Follow the same drilling sequence. Now how come I couldn't think of that? +++ #5001 From: Budd Davisson Subject: Re: Strut material Yep, we're using strut stock bought from Bob, so everything will work. We're going to figure out some sort of method of working with scratch builders so everyone can benefit from higher production and tighter tooling. One of our goals is to keep this thing really simple so we don't have to hire anyone to play stock person, so you'll be dealing directly with The Arizona Redhead. To that goal, we're going to limit the number of parts that can be bought individually, but I can already see that certain complex items, or really time intensive pieces, will be available. Also, as we get into it, Bob will be redesigning some pieces for easier production, to wit, the strut links. We'll keep ya advised. +++ #5158 From: "Dan Montee" Subject: Wing Struts OK, it's been quiet for some time so I'll offer up a question to get some discussion going. My Bride wanted to surprise me on Christmas morning (and she did) by giving me something for the Bearhawk. She had called Bob to see what she could purchase. On Christmas morning she gave the ubiquitous wrapped shirt box. When I opened the box of tissue I found what was recognizable as a Bearhawk drawing. As I looked at drawing 15A and thinking I had never see or heard of this drawing my son-in-law walked and presented me with the wing strut material. I was certainly surprised!!! Now my question: I have studied that drawing since Christmas and I am curious about the note, "partially flatten strut, between wood blocks, 4" on each end to obtain 1 1/2 dim." I realize that the strut I.D.is slightly over the 1 1/2 in dimension but why not make the end fittings meet the strut dimension rather than squash my spankin' new struts to meet the fitting dimension? I assume there is a good reason but it is not apparent to me. Dan Montee #415 +++ #5162 From: Kevin bearhwk272@a... Subject: Re: [Bearhawk] Wing Struts The only logic that I can find is the availability of material to make the strut end. I for one plan to build the strut end to fit the inside of an unsquished strut. If there be a reason enlighten us. >>> 2mar02 #7686-9153 +++ #8563 From: "flywithtwo" Subject: Wing Struts I recall that the wing struts can be made from salvage units off of a C182/C180. I also recall a thread that indicated that units off a Stinson 108-2 or 108-3 could be used. Is it possible to use C172 struts, or are they too short? I have access to a pair and was just wondering. Brian Cox, #478 >>> 20may03 #11298-18250 +++ #12121 From: "Fred Spain" Subject: corrosion proofing and struts???? ... Also, I bought a pair of struts from a Cessna 188 Ag Wagon for $20. They can be shortened and made to work. However, the material cross section is 1/4" wider and 3/4" longer than that called for in the plans. Can anybody guess how much drag/speed reduction this will cost me? Is it worth saving the cost of "The Bob's" strut material? All good advice on both topics will be appreciated. Thanks, Fred Spain +++ #12122 From: Budd Davisson Subject: Re: corrosion proofing and struts???? Re: strut drag It'll have an effect but I doubt if you'd be able to measure the difference on this kind of airplane. bd +++ #12633 From: jdug@p... Subject: Re: Re: Strut end material Hi from down under in NZ. The specs for the strut ends material specifies 2024 T3 or T4. I have been unanle to locate that but have 2024 T351. Does anyone know the difference, and is this suitable? Cheers, John H Dugdale +++ #12636 From: "Schutt, Barry C" Subject: RE: Re: Strut end material The material you are talking about (T351) has been stress relieved or some such thing like that , it still has the same mechanical properties as the T3, per the Boeing design manual the Rolled, drawn or cold finished bar(T351) has an Ftu of 62 KSI, T4 Ftu is 62 KSI, and T3 extruded is 65 KSI as well as T3510 and T3511. All good material---you're good to go! Barry(Boeing stress analyst)Schutt(036) +++ #13908 From: Russ and Penny Erb Subject: Strut End Fittings Has anyone contacted George Jenson about the strut end fittings that he is machining and selling? Does he have an e-mail address? Does anyone know his current price for the strut end fittings? Russ Erb +++ #13919 From: "t18cox" Subject: Re: Strut End Fittings I bought a set about a year ago and was pleased with the quality. I called him on the phone. Bill Cox #303 +++ #13925 From: lisankejm@g... Subject: RE: Strut End Fittings I got the strut fitting from George a while back and they are very nicely done. Machined and drilled according to the plans. I believe they were around $130 for the set IIRC. I think he has other machined parts for sale as well. Joe Lisanke +++ #13941 From: "Bruce A. Frank" Subject: RE: Strut End Fittings I don't know if this source of strut fittings has been discussed before, but do those supplied by D&E Aviation provide an alternative for use on Bearhawks. Bruce A. Frank +++ #13959 From: Budd Davisson Subject: Re: Strut End Fittings > I don't know if this source of strut fittings has been discussed > before, but do those supplied by D&E Aviation provide an alternative > for use on Bearhawks. I don't think so. Bob designed his own machining for this and, as far as I know, Jensen is the only one making them, although they are a straight forward CNC part. bd +++ #15136 From: Russ and Penny Erb Subject: Strut top end link guidance? For those who have been there, done that... Does anyone have guidance for welding the little link at the top of the strut? It needs to match up with the machined fittings perfectly and I seem to remember someone (possibly Bill Johnson) saying that he made the parts long to account for shrinkage. Or should I weld it on a jig, such as two bolts through a piece of 3/4" square tubing on either side to maintain the proper dimension? Soon I'll have to unwrap those struts I bought several years ago... Russ Erb +++ #15142 From: Del Rawlins Subject: Re: Strut top end link guidance? > For those who have been there, done that... > > Does anyone have guidance for welding the little link at the top of > the strut? It needs to match up with the machined fittings > perfectly and I seem to remember someone (possibly Bill Johnson) > saying that he made the parts long to account for shrinkage. > > Or should I weld it on a jig, such as two bolts through a piece of > 3/4" square tubing on either side to maintain the proper dimension? I welded those parts a few weeks ago so the memory is still fresh, and I went out and measured to be sure. Your mileage may vary since you are using oxy/acetylene and I used TIG, but I had no detectable lengthwise shrinkage of either link. What I did get, was some shrinkage causing one end of both links to grow in width slightly, on the end with the protruding tube. One grew about .005", and the other around .010". Basically the cooling weld bead shrunk slightly, pulling the flats slightly apart at that location. The width at the other end stayed where it was supposed to be, and since that is the end that has to fit between the wing fittings, I don't think there will be any problem upon assembly. For a pic of the finished parts, see: http://www.rawlinsbrothers.org/planes/images/strtlink.jpg If I were doing it again, I would maybe slide the flats down a hair farther onto the tube before welding, so that it would pull up to the exact dimension, but it's really a non issue. To hold it together for tack welding, all I did was put bolts w/ nuts of the appropriate sizes through each hole. If I were using oxy/acetylene I might go to the trouble of making a jig, which wouldn't need to be terribly fancy. If nothing else, the jig would provide a means to hold it to the welding table. Another tidbit for anybody who is welding up the small parts; I have a couple of large magnetic welding angle clamps and a steel welding tabletop. It's a great combination because by monkeying around with the clamps, I can arrange the parts at whatever angle is needed for a particular weld. I also bought a really cheap drill press vise that is sometimes useful for holding items to be welded. The nice thing is, using any of these items I can just fix the ground clamp to the table itself and forget about it. -- Del Rawlins +++ #15143 From: Budd Davisson Subject: Re: Strut top end link guidance? Bob has replaced that top link with a block of machined (or hacksawed) aluminum that is much easier to fabricate than the welded link. We're making them at the plant and I thought he had put them in a Bearhtracks at one point, but I could be wrong. Mike Meador: do you know if Bob has put out a drawing on the links or not? bd +++ #15144 From: Russ and Penny Erb Subject: RE: Strut top end link guidance? No such thing has been published. You've talked about it before, but no one has published anything. If someone could post a drawing or at least a picture I think I will be able to figure it out. Russ Erb +++ #15147 From: Budd Davisson Subject: Re: Strut top end link guidance? It's a simple item. I'm going to attach a crude drawing I just did of it (no laughing from you CAD/CAM guys) but it's not to scale so don't dimension from it. Also, I don't know the material, although 2024-T3 is a good guess. Mike Meador: do you know the material? [ See web-mail for attachment. ] bd +++ #15149 From: "areyouretarded" Subject: Re: Strut top end link guidance? The new linkage only goes out with the new strut material that Bob sells. You get new drawings to fabricate Alum ends. Later - Mike +++ #15151 From: "Dan Montee" Subject: Re: Re: Strut top end link guidance? Maybe I missed an update but my drawing 15a, the one that came with the strut material, still shows the welded link. Dan Montee #415 +++ #15153 From: Budd Davisson Subject: Re: Strut top end link guidance? That was a napkin. I had to erase the pasta stains in the corner. If I were making this, I'd create the inside radii by drilling the block and bandsawing into them. This is made for the aluminum strut fittings. I don't know if it'll work on the older steel ones. bd +++ #15164 From: Russ and Penny Erb Subject: Upper Strut Link Redrawn Based on budd's sketch and Drawing 15A, attached is a CADD file (dxf) that I drew up that should be really close to the actual dimensions. It nestles into the fork fitting with just enough room left for the wing spar straps. The drawing is attached since it is very small (9K). The overall dimensions are 1.5x0.91x2.62 You could make both pieces out of 1 foot of 1-1/2" square (available from Dillsburg or Wicks), although the Spruce (and Wicks) price for 1"x2" works also and is about a buck less. [ See web mail for attachment. ] Russ Erb +++ #15216 From: Del Rawlins Subject: Re: Results of Wing Test @AviPro One more question about the wing test Budd, did you guys use an actual Bearhawk strut with the fittings shown on the plans, or did you just use a chunk of steel? Not that I am the least bit concerned about the struts, I was just curious if they were part of the test or not? -- Del Rawlins +++ #15224 From: Budd Davisson Subject: Re: Results of Wing Test @AviPro We used a totally stock wing strut with all the fittings including the fuselage fitting that was welded to the fixture in such a way that it duplicated it's fuselage configuration. When the wing broke there was the slightest mark in the bottom fuselage fitting bolt. Not enough to call it a failure but enough to tell it had seen the load and that was the only thing that could be found in any of the strut stuff. Everything else was unmarked. bd +++ #15270 From: Russ and Penny Erb Subject: Strut Link, Part III Okay, you wanted dimensions. You got dimensions. I added them using the simplest and quickest method I know--with a pencil! Note this is not an official "Bob" drawing, but my interpretation of a "budd" drawing of a "Bob" design. I doubt there are any differences beyond very subtle ones. [ See web mail for attachment. ] Russ Erb +++ #15282 From: Budd Davisson Subject: Re: Strut Link, Part III No big differences other than it's 1.0" wide, not 1.5". That makes the radius at the bottom of the tang centered under the 3/8 hole, not on the hole center. That puts .430 of metal between the bottom of the hole and the bottom of the fitting for tear-out resistance. That's what the one on my desk measures. bd +++ #15385 From: Russ and Penny Erb Subject: Making the fittings fit... Calling all structural engineers...(budd)... By actual measurement, my wing attach straps (the .190 thick steel parts) have a width of .982 and .971. The corresponding gap in the aluminum upper wing strut fitting (from George Jensen) is .920, as per the plans. For Planter Bob (so he doesn't have to go find his calculator) that's .062 and .051 of interference, or .031 and .0255 on each side. The question: Would it be better to remove the interfering material from the steel straps or from the aluminum fitting? The skin is already riveted on the wing, so grinding down the spar is not an option. Russ "Stuck Again" Erb +++ #15402 From: Russ and Penny Erb Subject: What The Bob DID Say... The issue is making Erbman's upper wing strut fitting fit. Lets see, so far we have in the hopper: 1. I ain't no gonna say -- bd 2. Take some of both (aluminum and steel) -- Planter Bob 3. First, drill out all the wing rivets... -- Bruce Gagne 4. Make a fitting that fits -- Del Rawlins Well, I was forced to use the telephone (for some reason I have an aversion to that) and call The Bob. And the answer was... 5. OH MY! You must scrap both of your wings! You only have 8 rivets on the bottom of the nose ribs! You must have at least 9! (...okay, not really...but if you have no idea what that was about, consult your Bearhawk CD. If you don't have a Bearhawk CD, order one now! Go to http://www.qnet.com/~erbman/bearhawkcd.htm -- only $20!) Actually the answer was 5. None of the above--you didn't give us enough information! The Bob, being the Bob, started asking some questions. It turns out that my 0.190 4131 plate from Spruce lo those many years ago was really 0.200 thick. That accounts for .020 of the .062 and .051 excess. Add about .003 for the primer film. That leaves .039 and .028 excess, which is the amount the straps are farther apart than the expected 0.532. Anyway, taking 0.010 off of each steel strap is obvious, since that would bring the strap down to the 0.190 dimension shown on the plans. As for the rest, The Bob said to take the rest of it off of the steel straps. That will leave the straps either 0.0195 or 0.014 undersize. Okay, Bearhawkers, time to score your papers. budd, report how you did. Russ Erb +++ #15405 From: Budd Davisson Subject: Re: What The Bob DID Say... I wondered about the steel thickness because aluminum is almost always right and steel never is, but didn't think to ask the question. As for the primer: we opened the wing fitting dimension up on the factory fuselages just a little primarily because of the build-up from so many layers of primer. bd +++ #15413 From: Del Rawlins Subject: Re: What The Bob DID Say... > The Bob, being the Bob, started asking some questions. It turns out > that my 0.190 4131 plate from Spruce lo those many years ago was > really 0.200 thick. After you posted that, I just had to go out and measure my straps, which were also made from steel purchased from Aircraft $pruce. Mine are actually a hair undersize at .185". So I will have an extra .010 to play with when it comes time to bolt the parts together. I'll still be surprised if I don't have to make my aluminum fittings a little oversize to make up for the added thickness of primer on the aluminum parts and powdercoat on the steel. I was actually thinking of buying those fittings but will likely hold off until after the spars are built. Thanks for the heads up. -- Del Rawlins +++ #15416 From: Russ and Penny Erb Subject: Strut Link Part V Hopefully this will be the end of this saga. After several iterations, attached is the best drawing I can make of the strut link that is sitting on budd's table based on e-mail exchanges. Of course, any of you could step up and ask The Bob to release his drawing. Question to anyone who recently bought strut material with its associated drawings--does it still show the welded strut link or the aluminum one like shown here? Russ Erb [ See web mail for attachment. ] +++ #15995 From: Russ and Penny Erb Subject: Tiedown rings For Pat Fagan: I noticed that you installed the Bob-style tie-down rings at the wing-strut junction. (For those who aren't familiar with this, it is essentially a washer on either end of the strut attach bolt with a partial ring welded between them) For the "washers" did you use washers or cut a piece of 4130 and drill a hole in it? What thickness? What did you use for the ring? Did you bend a solid rod or a piece of tubing? What size? Thanx! Russ Erb +++ #16002 From: Pat Fagan Subject: Re: Tiedown rings > I noticed that you installed the Bob-style tie-down rings at the > wing-strut junction. I made the washers out of .032 4130 and made them pear shaped so there would be a larger surface to weld to and still allow a full, flat surface under the nut. The ring is just 1/4 inch mild steel rod, bent in a U shape with the ends flattened to conform to the the pointy shape of the washers. Pat Fagan +++ #16170 From: Russ and Penny Erb Subject: Right Wing Strut Is In Well, I finally did it. I've been dreading installing the wing strut for years now, probably because the thought of cutting on a $125 chunk of aluminum was daunting, not to mention irreversible. It has to be the right length the first time. Because I was dreading it, I've been putting it off as long as I could. I've also thought through the process several hundred times. I went through it slowly and deliberately, and it did come out perfect the first time. What I wanted you to get out of this was this: The plans call for 4 inches at each end to be flattened (smooshed) to fit the fittings. The issue is that the fittings are made from an aluminum block 1-1/2 inches square. In the strut material, the gap between the flats is 1-5/8 inches. I had wondered if the smooshing could be done in a bench vise or was a hydraulic press required. I'm happy to report that a bench vise is plenty sufficient. One issue that comes up during the smooshing is springback, aka "the pro perty of 2024-T3 we most like to hate". 2024-T3 has more than its share of springback. If you smoosh it down to a 1-1/2" gap, it will spring back to its original size, elastically laughing at you. Therefore, you have to over-smoosh it. However, it is very difficult to unsmoosh it, so you need to keep track of how much you smoosh. Do a little bit, let it out, measure, do a little bit more. Repeat. Stop when it is the right size. So much for that. In a few months I'll get to do it again. Russ Erb +++ #16175 From: bearhwk272@a... Subject: Wing Strut Material ? Re Russ comment... wing strut. Is the strut 2024 or is it 6061? I do not think that 2024 can be extruded to this shape? Just wondering. Kevin Bearhawk +++ #16182 From: Russ and Penny Erb Subject: RE: Wing Strut Material ? Good catch, Kevin. Referring to the plans, replace all occurrences of "2024-T3" with reference to the wing strut to "6061-T6". The fork fittings at either end are 2024-T3/4. "It ain't the things we know that get us in trouble. It's the things we know that ain't so..." Russ "Caught Me Again" Erb +++ #16184 From: Russ and Penny Erb Subject: RE: Right Wing Strut Is In > Is there any good reason not to make the fittings to fit the strut > material, rather than the other way around (for those of us who > don't already have the fittings). Then no smooshing would be > required. Or, is there any good reason not to put 1/16" aluminum > shims on each side of the fitting? Other than you would pay for an extra 1/2" of aluminum just to machine away all but 1/8" of it? Actually, there is no reason to be worried about the slight smooshing. It's really minimal, and I doubt any non-Bearhawker looking at my strut would even noticed that it is slightly smooshed. > If your struts came from the same batch as mine (the first), then > they should be 6061-T6. My bad. The end forks are 2024-T3, the strut itself is 6061-T6. Bad memory. See response to "Kevin Bearhawk" > Another question. Did anybody actually make the original design > fittings other than The Bob? Just out of idle curiosity, how does > one get inside the strut to buck those big rivets? It would seem to > be critical that they be done properly, and yet next to impossible > to execute. I also made the new strut links from 2024-T3 instead of welding from 4130. Russ Erb +++ $Id: 2.1.4-Wing-Strut,v 1.8 2003/05/21 14:58:46 bentonh Exp $