+++ #692 Subject: Wiring Conduits From: Russ Erb I plan to use a wiring conduit (tube) in my wing to run the wires for the nav lights, landing lights, strobes, wingtip VOR antenna lead, and whatever through. Several of my buddies building plastic airplanes are using thinwall PVC pipe for wiring conduits. In that application, PVC makes a lot of sense since the PVC can be bonded into the structure. However, in an aluminum wing, such a tube would have to be supported by multiple clamps. PVC pipe is flexible, but can also be brittle and subject to cracking. What about an aluminum tube? Aluminum is generally ductile and would not be as prone to cracking, especially around holes cut to let the wires in and out. I decided to compare weights. Weighing a piece of 1" thinwall PVC pipe I had available, I got an answer of 0.1713 lb/ft. Per the Spruce catalog, 6061T6 aluminum tube 1" x 0.035 (thinnest wall available) is 0.1275 lb/ft. Conclusion: the weight difference between aluminum and PVC is not significant. If a slightly thicker wall aluminum was used it would be heavier. Based on this, I'm leaning toward using an aluminum conduit based on the other material properties of aluminum. +++ #693 Subject: conduit From: Bill Cox Russ I used aluminum tube in my T18 wing and have fished several wires through it over 20 years with no problems. +++ #761 Subject: Wiring Conduits From: Russ Erb Cancel that! In a previous message (see below) I explained why I decided to use aluminum tube for electrical conduits. At the time I was just looking at weight. I forgot about that all important factor: cost! As I was making up an order, I noticed that 10 feet of 1-1/2" x .035 6061T6 Aluminum Tube would cost $22.50. 10 feet of 1-1/4" x .035 is worse at $29.00. On the other hand, a 10 foot piece of 1" thinwall PVC (roughly equivalent to 1-1/4" x .035) would cost well under $5 at the local home center. For virtually no difference in weight, the difference in cost is overwhelming. I'm back to using PVC pipe now. +++ #764 Subject: Re: Wiring Conduits From: Daniel Fox The cost differential seems to be 6 bux vs. sixty bux plus-or-minus from what I read here. 10-to-1 sounds overwhelming, but an additional $54 doesn't sound too bad, if there's something to be gained. My first thought is EMI protection. Would the AL tubing serve to keep any electromagnetic nasties either out of where they don't belong, or trapped where they do belong? Strobes are a traditional source of radio noise; will the AL solution help there? Or would this serve no purpose other than to trap the source and sink inside a tube with each other? Also, which is going to survive the long term better in that environment (temperature extremes, vibration, flexing, etc.)? I'd hate to be preflighting some nice morning and see a bit of (AL|PVC) drip out of the trailing edge of the wing when I exercise the ailerons stop-to-stop. +++ #768 Subject: Re: Wiring Conduits From: Russ Erb > My first thought is EMI protection. Would the AL tubing serve to keep > any electromagnetic nasties either out of where they don't belong, or > trapped where they do belong? Strobes are a traditional source of > radio noise; will the AL solution help there? Or would this serve no > purpose other than to trap the source and sink inside a tube with each > other? I don't claim to understand shielding hardly at all, but my understanding is that to work as a shield the tube has to be grounded. The tube wouldn't be grounded sitting in rubber lined Adel clamps unless I specifically made it so. For EMI supression, the VOR antenna lead is in a conduit in front of the main spar. The strobe lines, which are in a shielded cable, are in a separate conduit near the rear spar. Power wires for the position lights, landing lights, courtesy lights, and Pitot heat are in the same conduit with with antenna lead, but each positive wire is twisted with its corresponding negative wire, which effectively cancels out the E-M fields. Antenna guru Bob Archer has told me that I should be okay with this setup. Note that I'm wiring the airplane as though it were a composite aircraft, that is every circuit has a return ground wire. Using the airframe as ground promotes corrosion and leads to electrical problems like ground loops. As for the material, I'm far from being the first to use PVC for this purpose. Composite builders like it because it can be bonded into the structure. In this case, any loads on the pipe will be very small, and if well secured it shouldn't beat itself to death. As for flexing, PVC is far more flexible than aluminum. Risk of failure shouldn't be any more than for any other part of the airplane. +++ #2498 From: Rod Smith Subject: Re: Wingtip thoughts... > For the aft position light (white), Just a clarification here. Grimes makes a taillight for the rudder that comes with a steel ring that is welded on as an integral part of the rudder. Best done during the construction process rather than a later add on. It has predrilled holes to capture the screws that hold the base of the light unit. I went back and forth before finally deciding that I would put all my lights in the wingtip. I dont think the wiring issue is a real concern as the wire to the rudder light in my Maule was still in good condition 15 years after new. I thought I would just use the 3 in one Whelen wingtip unit but Russ has some great ideas. Also with the antennas. +++ #2838 From: Rob Gaddy Subject: antenna location I was thumbing though a couple of the aircraft parts supply catalogs and noticed a comm antenna that is to be located inside a fiberglass tip of a metal (presumely a RV) airplane. Has anyone had experience with these anetnnas? I assume that they will fit the tip being offered in the BH newsletter. Is the best solution to just use the standard whip antenna attach the the top of the fuselage using the wing-to-fuselage fairing as the attachment point? +++ #2841 From: Russ Erb Subject: [Bearhawk] antenna location > I was thumbing though a couple of the aircraft parts supply catalogs > and noticed a comm antenna that is to be located inside a fiberglass > tip of a metal (presumely a RV) airplane. Has anyone had experience > with these anetnnas? I assume that they will fit the tip being offered > in the BH newsletter. Is the best solution to just use the standard > whip antenna attach the the top of the fuselage using the > wing-to-fuselage fairing as the attachment point? After discussions with Bob Archer, I am putting a Bob Archer antenna in a wingtip for VOR/ILS, which are horizontally polarized signals. The COMM antenna needs to be vertically polarized, so I will be using an external antenna attached and grounded to the fuselage tubing at the "X" above the center of the cabin. Bob told me this would give the best ground plane for the comm antenna since it would be using the fuselage frame and wings. If you use the wingtip VOR antenna, be sure to look carefully at the size of the antenna. You may find you need to give the fiberglass tip just a little more span. That's about the extent of what I know about antennas. That's why I talk to people who do understand them. +++ #2843 From: Mark Goldberg Subject: Re: [Bearhawk] antenna location I used the antenna you are asking about, I think. It is made of strips of aluminum by a fellow named Bob Archer. They do fit inside the RV wingtips. The comm version and the "vor" version are almost exactly alike, with the VOR version having one of the "strips" of aluminum 3 inches longer. The comm version likes to be placed vertically, and the VOR one lays down inside the wingtip. I have 2 of the comm antennas, one in each wingtip of my RV-8. They perform VERY well - and no drag. +++ #2844 From: Bob Romanko Subject: RE: [Bearhawk] antenna location..Bob Archer's URL Here's the URL. I'm planning on going with these as well. http://www.pavionics.com/antennainfo1.htm +++ #2845 From: Bob Romanko Subject: RE: [Bearhawk] antenna location..another URL Here's Bob Archer's description URL: http://www.pavionics.com/antwing.htm Well, not a description of BOB, but of the antenna (grin)! +++ #2846 From: Russ Erb Subject: Re: [Bearhawk] antenna location > I used the antenna you are asking about, I think. It is made of > strips of aluminum by a fellow named Bob Archer. Mark--how vertical are your comm antennas as installed? Are they connected to separate receivers? The comm antenna is shorter than the VOR antenna to center it in the comm frequency band. Bob Archer came to our EAA Chapter 1000 meeting a while back. He warned that you should not put an antenna in each wingtip and then try to couple them together. The wingtips are just enough wavelengths apart such that the antennas will be out of phase with each other and cancel each other out. It is okay to have antennas in both wingtips if they are connected to different receivers. I plan to use the one VOR antenna to drive the VOR/ILS, the glide slope, and even an FM radio (the FM band is just below the VOR band--not optimal but good enough). That's a lot to ask of one antenna, but my primary nav mode will be GPS, and glideslope and localizer are at such close range that it shouldn't be a problem. Of course, if you are a true disciple of Bob Barrows, you are wondering why we are talking about this at all, since electrical systems don't belong in airplanes! Use a handheld radio if necessary! You can e-mail Bob Archer directly at bobsantennas@e... +++ #2849 From: mailstuff Subject: Re: [Bearhawk] antenna location Try RST technololgies in Grass Valley, CA. Jim Wier offers the copper tape, torroids, and instructions on how to make the wingtip antennas for next to nothing. +++ #2850 From: Hedges, Bill Subject: RE: [Bearhawk] antenna location Usually the antennas in the wing tips are for receivers only, i.e. nav radios, I have a friend with a Mooney (speed nut) who has as many buried as possible, there seem to be no ill effects in the radios, but the comm antennas are still out in the breeze, also DME and XPNDR, but they are not as big, and in turbulent cowling exhaust air. +++ #3484 Subject: Landing Lights From: Rob Gaddy I had the opportunity to visit the aircraft museum at Boeing Field near Sea-Tac. Hanging were a couple of classic airplanes (I've forgotten just exactly which) that had landing lights installed (it appeared) just behind the main wing spars under the wings. These lights seem to be of the retractable type, flush with the wing lower skin when not used (pointing down), and extending to point forward when needed. I did a web search and note that this type of light is used on some Cessna aircraft at about $4,000 each. I wonder if a smaller type motorized unit using modern small bulbs could be made to fit in a wing inspection plate type area under the wing. This would allow for an unbroken leading edge, and eleminate the water sealing problem that Bob addresses. Bob recommends mounting landing/identification lights on the nose which still is a very attractive choice. Zenith has some lights that mount in the wing tips, which also appear to be good choices. Does anyone have discussion points (yea sure, this crowd is so reserved that no one will probably say anything)? +++ #3485 Subject: RE: [Bearhawk] Landing Lights From: Bob Romanko Don't listen to me, 'cause I'm sure some of the fancy engineers in the group will tell you all about their servo-pneumatic- hydraulic-vacuum-assisted thingamajig they drew on CAD, cut out with a LASER, cleaned up with a CNC and polished with a small sub-atomic bombarding process in some solution you can't even pronounce. It's been tested, inspected, and generally prodded at for the past three years. Protected with Teflon, iodized, anodize, black oxided, three different chromates, dipped, stripped, and clipped. The wiring diagram was drawn out by Jim Weir, and tested through a myriad of voltages and temperatures, from 0-100 degrees C. (Engineering types don't use Fahrenheit, you know). Mine's going in the nose bowl, right where God and Bob Barrows meant for it to be. The most advanced thing I'm doing with my light is to mount the filament vertically so my Advanced Auto parts bulb lasts longer. +++ #3490 Subject: Re: [Bearhawk] Landing Lights From: Your local NAPA auto store should have the small (4 or 4 1/2 in. dia.) bulbs. I mounted 1 on left out board of strut straight ahead. right wing down 20 degrees out board of the strut. Spring loaded for down in to air stream, release was a pull knob in cabin. Keep them behind the strut so they don't blind you. You have to lock them up during tie down. You also mite prefer 30 degrees down on the right. Steve +++ #3495 Subject: RE: [Bearhawk] Landing Lights From: joel MAYHALL I believe the landing light you saw was one made by Grimes. I have one on my Bellanca 14-13. $4000 sounds like an awfully high price to pay, I would gladly sell mine for only $3,333. As for location, my pervious Cessna 140 had one mounted on the left wing. Two problems I noticed with that location were the peripheral light glare and a noticeable yaw from the drag on landing (not to mention that my radio would not work due to high amp drain on the battery). My Bellanca has the Grimes light located under the seat area of the fuselage. The yaw and light glare are not a problem with this location. The light construction is relatively simple. The light is extended and retracted by a single directionally geared motor with a stop at the full extension. The motor on\off switch allows you to nudge it further up or down. I imagine someone could devise a simple mechanical device to deploy one. Joel PS When I got my engineering degree, (1962) we were using the Fahrenheit temp scale at General Dynamics/Pomona. +++ #3496 Subject: RE: [Bearhawk] Landing Lights From: I really like the under seat mounting location idea. In the BH, the light (lights) could be mounted under the aircraft, and shine through the landing gear when deployed. An "Armstrong" motor (pilot's arm) could be used to deploy the light, and could adjust the aim point for taxi, takeoff as required. The only drawback that I see could be damage when operating from fields with bushes (bush flying?)and perhaps exhaust and oil from the engine. Maybe a short lever mounted next to the flap lever. Short length electrical wires, and come to think about it, a seat warmer to boot! ;-) +++ #3498 Subject: Re: [Bearhawk] Landing Lights From: Tex and Pat Goerger I have a Grimes landing light that I removed from my 1947 Cessna 140 some years ago and replaced it with the new style, in the leading edge, light. It is complete with the mounting bracket that fits between the ribs. It was in working order when removed and I'd be willing to part with it. +++ #3513 Subject: Landing Lights Location From: Just a thought. I have been thinking about this issue and if I don't go in the nose bowl the next best location would be buried in the strut to wing faring. This is a high drag location and a good size faring at this location could easily handle a light. Take a look at a Howard DG-15. The fairing looks huge but is very low drag. Mounting the light to the outside would stop the glare in the cabin. Just a thought? +++ #3600 From: Rob Gaddy Subject: Copperstate observations I walked the ramp at Copperstate with an eye toward landing light installations. The new / small high energy bulbs were used by several aircraft. Installations included: just inside the cowl looking out the intakes, on the cowl under the prop, on landing gear (retractalble), and in wing leading edges. But the most popular location seemed to be in the wing tips. I noted several installations with the landing/identification lights grouped with the clearance lights, and sometimes strobes,in clear plastic covers on the wing tip forward areas. This was most common on smaller types, Lanceairs and Glassairs. I think that wing tip lights would also be effective on our longer wings with the possible exception of landing on a "real" wilderness runway, narrow with bushes on the sides. I was thinking of mounting two small landing lights in each tip, with the clearance lights mounted external to the tip, further aft in the conventional location. +++ #3608 From: Subject: Re: [Bearhawk] Copperstate observations I have been hankering for landing light installation in the wing tips as well. I like the idea of having themout there and installing a flashing device for visibility. I have wondered though if the heat from the bulb being on almost continuously will be detrimental to the plastic lens. Will it need to be vented for cooling? Also, being a taildragger, how effective will the light be for taxi if it is set up for cruise? +++ #3610 From: Bruce A. Frank Subject: Re: [Bearhawk] Copperstate observations At what does the light need to aim at cruise? The method with two lights is usually one aimed to illuminate the runway on final and the other aimed to provide good vision while taxiing. There can be a bit of parallax problem when attempting to align the runway illuminating light, if it is a tight beam spot light, when it is at the wing tip. Certainly all lights aimed forward, whether aimed horizontally at cruise or slightly dipped for landing, are going to show up well while flying. +++ #4651 From: Tim Subject: Project Description and System Schematics Been surfing around the net, looking for some stuff for the Group...Found this builders page with very nice schematics of Vacuum/Fuel/ Electrical and Pitot/Static System drawings.....Drawings start .5 way dwn pg. +++ #6220 From: zipppydoggg@y... Subject: antenna in tip? > My wingtips will be pretty much like Bob designed them, with a > slight change in size to accommodate an antenna. Just curious, would you share your plans for an antenna in the wing tip? Com (usually)uses a vertical antenna and Nav (VOR)a horizontal one. Are you going to mount VOR in one (two?) tips? I've been wondering about this since I first noted a mention of it. I thought you may have shared in CD version 2, but alas I didn't find a mention. I'm a long way from deciding, but was planning a vertical com antena to be mounted in the fairing between the wing and fuselage, and a GPS somewhere on top either on top of or below the fabric or skylight. One COM and one GPS mounted in the plane and a handheld for back-up was my plan. Not planning to fly IFR (got lots of those hours). Rob Gaddy BH401 +++ #6228 From: Russ and Penny Erb Subject: RE: [Bearhawk] antenna in tip? Search for "Antenna Locations" on the Technical Guidance page. In short, I'm using a Bob Archer Sportcraft VOR antenna (Model 3 I think) in the left wingtip to drive VOR/ILS/Glide Slope. I'll have a simple wire of the right length in the right wingtip for the marker beacon. The transponder will have the traditional little one poking out the bottom. The primary com antenna will be attached (vertically) at the center of the crossing diagonals between the wing roots and grounded to the structure, using the fuselage tubes and wings as the largest possible ground plane. I haven't asked where to place the second com antenna, but it will probably be on top of the fuselage halfway between the primary com antenna and the vertical fin. They need distance between them to reduce crosstalk. This becomes an issue if your audio panel will let you split the radios between crew positions. This setup was recommended by Bob Archer during discussions while he was visiting our EAA chapter. He also recommended how to run the position light and strobe wires relative to the antenna so they wouldn't interfere. Don't ask me any tougher questions about antennas--I'm not sure I know enough to be dangerous. Contact Bob Archer instead. Having said that, I think I heard mounting a com antenna on the fairing between the fuselage and wing distorts the antenna pattern to one side. And since Planter Bob would probably ask, my understanding of proper usage is that an airplane may be festooned with many antennas, while most insects come with at least two antennae. (Don't you just love that word "festooned"?) Russ Erb #164, Edwards CA +++ #6238 From: Brian Cox Subject: RE: [Bearhawk] antenna in tip? Just a few thoughts. I'm an antenna engineer by training and experience. Being based at Edwards AFB, you are probably familiar with the C-137 avionics test bed, project Speckled Trout. I designed the Inmarsat satcom phased array installed on it. I have spoken with Bob Archer in the past about wingtip antennas. He's a nice guy, and makes some pretty neat antennas. Having said that, I think the printed circuit antennas he provides are best suited to composite aircraft. It is very difficult to obtain a nice pattern shape with a horizontally polarized antenna, such as the VOR, when installed on an aircraft. The wingtip is a neat installation option, but will have some pattern distortion in azimuth (around the yaw axis). The typical cat whisker (mounted on the top leading edge of the vertical stabilizer) is a half wave dipole. By bending it into a Vee, the normal donut pattern is distorted enough to fill in the two nulls, and provide a reasonably uniform pattern. The towel bar or blade styles mounted on both sides of the tail are a balanced loop, and will probably provide the most uniform pattern. However, these are not very amenable to a tube and fabric vertical stabilizer. One problem with wingtip VORs is that installing it in one wingtip will have poor gain in the direction of the opposite wingtip, just due to wing and airframe blockage, some diffraction effects, and the inevitable ground plane effects of being close to the end of the metal wing. Dipoles work best in free space, not close to metal objects. The objective is to understand it's interaction with the airframe. The ultimate would be to actually take the interaction into account and have it improve the overall pattern, which is a noble goal, but probably not realistic for a horizontally polarized antenna. The second best effort would be to understand it well enough that the worst effects are mitigated. If we consider the possible effects, the choice and placement of antennas offers considerable latitude in making tradeoffs. A poor installation of the best antenna will result in some pretty disappointing system performance. I don't want to preach doom and gloom, so please bear ! with me, and I can offer some suggestions. It might seem logical that one way to counter the distortion of a single wingtip antenna is to install an antenna on both wingtips and connect them via a two way coax combiner, but there's a catch. One wavelength at 113 MHz (middle of VOR band 108-118 MHz) is 104 inches. Thus the wingspan of 33 feet is a bit less than 4 wavelengths. Consider the airplane sitting on the ground, transmitting out of both antennas. Consider being a distance from the airplane, such as 2-5 miles, where the wingtips (the whole aircraft for that matter)look like a single point source and the wave traveling from them arrive effectively parallel, but with different path lengths. As you circle around it at this given radius, there will be periodic nulls where the total path difference between the two antennas is some odd multiple of 52 inches, or one half wavelength. The phase difference between these would be 180 degrees and the two antennas would cancel, resulting in a pattern null. Likewise, t! here will be locations where the phase difference is zero, or some multiple of one wavelength, such as the nose and tail of the airplane, the signals would combine constructively, and there would be a pattern peak. If the coax length to the two radiating elements is not identical, you would still get the same number of nulls and peaks, they would just occur at different locations. For instance, if the difference is one half wavelength, the nulls and peaks would just interchange. However, there is no way to passively combine the elements to get rid of the nulls. One way to avoid this is to place the two radiating elements fairly close to each other in terms of wavelength. Thus the towel bar is really two elements spaced about a tenth of a wavelength apart. The composite pattern can be made very uniform. Another way would be to have a switch between the two wingtip elements. If one has poor reception, the other would probably have good reception. Then the question becomes how the pilot, who is busy flying the plane, would make a decision on which antenna to select. Another option would be to have the two wingtip antennas, with one connected to each of two VORs. If reception on one dropped and the NAV flag indicated such, tuning the other radio has a good chance of getting good reception. It still requires the pilot to be involved in choosing the best one of two. As far as VHF Comm antennas are concerned, your best placement would indeed be top center between the wing roots. I don't think the pattern would suffer too much if it was displaced to one side or the other. The mid fuselage location for the second Comm antenna would also work fine. I see a lot of 172/182 installations with the two antennas side by side over the pilot/co-pilot. That could indeed cause some interaction. If they were ~40 inches apart, that would be less than one half wavelength, and there could be some mutual coupling which would distort the patterns. I had a Mooney with one over the pilot and one aft on the fuselage. There was definitely better performance out of the front antenna. One reason was better line of site, as it was at the highest point on the fuselage, where the second one was on the backward slope. The other is that they were both the "hockey stick" shape, which had a lot of horizontal polarization. The swept quarter wave whip style has more vertical, and should perform a bit better even if it isn't as sexy looking. My 310 has a combination VHF Comm/VOR antenna on the top middle fuselage between the pilot/copilot. This is quaintly known as the "flying lady" antenna. Wag Aero calls it the NAV-COM broadband, and it's priced at a whopping $666.75. Not a good choice for the homebuilder - I was just lucky it came with the plane. The center post has the VHF Com and the swept wings have the VOR/GS element. Performance is outstanding, primarily because it's probably the optimal location on the airframe. The second Comm antenna is mounted below the tailcone, and is also bent back at 90 degrees (on purpose). Due to the location, it's performance is generally not as good. However, it does provide a lot of diversity. If the #1 Comm is experiencing blockage, the #2 is most definitely not. Even so, this could be a non starter with a taildragger, and especially one on floats. Perhaps a swept no. 2 Comm moved further up would provide good diversity and still be workable on the belly. After all of that, here is what I would recommend for your configuration: 1. VOR antenna choice: a) Cat whisker on top of vertical tail, swept forward or backward. Re: Aircraft Spruce P/N AV-532 from R A Miller. b) or Archer antenna in one wingtip for the single VOR. Be aware that the pattern may not be uniform. 2. Marker beacon choice: a) If you use a wire, it will have to have a transformer to be resonant at 75 MHz. A single wire at one quarter wavelength is 39.4 inches. Take a look at the sled style ones that are belly mounted on some planes. They are about this long, but are fed from a grounded shunt. I'm not suggesting the use of a sled style, just that you look at it to see how it's fed. b) The other alternative is a boat style mounted on the belly, which is about 12" long and 1-2" tall. 3. Transponder choice: a) Chrome plated bronze stud, mounted on belly or lower cowling. Re: Aircraft Spruce P/N AV-22. 4. Comm choice: a) #1 swept whip mounted at highest practical fuselage point, close to centerline. Re: Aircraft Spruce AV-529 b) #2 mounted aft on fuselage centerline. Re: Aircraft Spruce AV-529 c) or #2 bent whip mounted on belly aft of gear. Re: Aircraft Spruce CI-122 5. GPS choice: a) Bracket mount on glareshield offset to either side away from fuselage structure. I've had outstanding luck with yoke mount GPS and the antennas set up on the glareshield. The Mooney had a center steel tube and the Cessna has a two piece windshield with a metal center strip. The 207 had single piece windshield but the high wing. If the antenna is forward there is plenty of view to the sky. This would be the easiest install. If the performance does suffer, the alternative is an airframe mounted antenna. 6. TCAS, Satcom and X-Band Radar choice: Just kidding. Here's my proposed configuration for Bearhawk #478. I won't be IFR. Comm 1. Built in radio, antenna on top of fuselage Comm 2. Belly mount bent whip to connect to handheld backup radio GPS. Glareshield mounted. Use iPAQ from Control Vision, can use either HSI or EFIS presentation. GPS backup, have several to choose from. Transponder. Chrome plated bronze stud. No VOR, ADF, Marker Beacon. For what its worth. Brian Cox, #478 +++ #6244 From: Ken Beanlands Subject: RE: [Bearhawk] antenna in tip? I have been looking at an appropriate place to mount the COMM antenna on my Christavia and had been thinking about putting it on a shelf above the steel tube structure behind the cabin. There is a metal shelf in that location that will support the ELT, battery relay, first aid kit, etc. The only thing above this shelf is a single cross tube, two wood stringers and fabric. It will be on the centerline of the plane and fairly high. You can see the area I'm thinking of in the following photo just above upper longeron, between orange level and the stand holding up the rear of the fuselage. http://www.spots.ab.ca/~kbeanlan/struts2.jpg What is your opinion on this type of installation in a fabric covered plane? I was trying to avoid an antenna above the cabin as it would require a higher hangar door. The belly is not that great either as this bird has a pretty low stance and I do intend to use it off field on occassion. The rear area behind the cabin is fabric only that doesn't give much of a grounding plane. Obviously, if this is OK, a similar location could be used on the BH. Thanks. Ken Beanlands B.Eng (Aerospace) +++ #6248 From: Brian Cox Subject: RE: [Bearhawk] antenna in tip? If I understand it, you want to use the shelf as the ground plane. That will work, as long as it is of sufficient size, say about 2 feet by 2 feet or larger (61 cm by 61 cm for metric). The ground plane could be extended by using wires arranged like spokes, say about 8-12 of them, or foil or metal screen or metallized mylar. Since the ground plane is inside of the airplane fabric there aren't any aerodynamic issues. If I understand it correctly, the shelf is mounted inside the fuselage maybe 6 or 8 inches below the outer fabric, and a portion of the whip comes up through the fabric and is mostly visible - maybe with a grommet where the whip goes through the fabric. The max height is less than the top of the tail, thus allowing the vertical stabilizer to set the hangar door height. Please correct me if I have this wrong. There may be some antenna pattern distortion from the metal tube, but if you don't mount it too close, I think it should be workable. Try to clear the tube by at least a foot or so. All of the wood and fabric will be effectively transparent to the signal at VHF frequencies. Another option would be to use the 45 or 90 degree bent whip on the fuselage, such that it is shorter than the vertical stabilizer. You could put a metal or wooden fitting below the fabric to physically mount the antenna. Wires, mesh, metalized mylar, etc. could be attached to the inside of the fabric as a ground plane. Then the metal base plate of the antenna should be bonded to the ground plane with something like braided wire. The quality of this bonding will directly affect the antenna performance. I hope this is helpful. I'd be glad to work with you on optimization. By the way, nice looking fuselage. I hope to be there in 4-5 years. Ribs this year, Spars next year, and so on. Best regards, Brian Cox, #478 +++ #6256 From: zipppydoggg@y... Subject: antenna in tip (continued) Please pardom my ignorance, but isn't there a magic black box that could pick out the stronger VOR signal (assuming one in each tip) and send it along to the VOR? Would it be "simple" and/or cost a fortune? It seems (from your excellent post)that the "fling lady" has some major advantages, amount which is being an "all in one" unit that would mount close to the instrument panel. You pointed out the major disadvantage is cost. Couldn't a "flying lady" be fabricated? I know there are some good fabricators in this group. Rob "I have a long time to decide" Gaddy BH401 +++ #6258 From: Russ and Penny Erb Subject: RE: [Bearhawk] antenna in tip? Thanx, Brian. Glad to see a nice meaty post from someone else. Yes, I'm familiar with the Speckled Trout. See it on the ramp here frequently. Bob Archer said the same thing about why coupling antennas in both wingtips is not a good idea. I expect that the wingtip antenna would be primarily used for ILS/Localizer and rarely for VOR, so I think I can live with lesser reception to the right. Besides, if you use VORs for tracking to or from, the fore/aft direction is the more important. There are those crossing radial things that could come up, though. There was some mention of needing a ground plane. My understanding was if the fuselage truss was used as a ground plane, the tubes were close enough relative to the wavelength that they appeared as a solid surface. That avoids the weight of additional metal. My next question is that if I mounted the antenna to the fuselage tubes, would that cause a problem with the aluminum stringers running next to the antenna? Should I move the mount up to the level of the fabric? This would be an issue with the comm antennas on top and the transponder antenna on the bottom. I figure that putting the antenna inside the truss would be bad, so having the base partially inside the stringers might be a detriment. This isn't my area of expertise, so I welcome the advice. Thanx for recommending a specific part number for the comm antenna. Why did you put the GPS antenna on the glareshield instead of on top of the fuselage where I would think the visibility of satellites would be better? I mount the fire control radar antenna in the spinner. It has a good view, but it is a little difficult interpreting the display when it's spinning at 2400 RPM. Russ Erb +++ #6275 From: Brian Cox Subject: RE: [Bearhawk] antenna in tip (continued) Disclaimer to Bearhawkers. This is long winded. I apologize in advance for those who like their responses short and sweet. Although I truly enjoy this, I realize that it may put most folks to sleep. BC Hi Rob, I can think of a way to do it. To select the right antenna or steer a beam, three items are required. 1 - a means of switching or steering the antenna; 2 - a means of receiving the desired signal and measuring the received power, or a means of knowing/determining the location of the transmitter and receiver; 3 - a means of deciding what state to set the switch or beamformer in, based on the received signal or the known locations. The difference between switching and steering, is that switching involves selecting the best antenna among two or more. Steering involves combining the signals from two or more antenna elements, to get the best reception from the desired ground station. In the case of the two wingtip elements, they could be switched by a simple coax single throw double pole switch. There is another way to do it that is very simple from a switching standpoint, which is known as "adaptive combining". Combine both antennas in a two way coax combiner, as was described in my earlier posting. Place a device in one coax path known as a phase shifter. Think of this as a black box with an arbitrary length of coax inside. If it offers an alternate path that is exactly 180 degrees longer, and a set of switches to choose between the two paths, it can be toggled for a relative path delay of either 0 or 180 degrees. Note that this difference only has to be relative. Once the signals are received in phase, adding 360, 720, 1080 degrees, or any multiple of a full wavelength, will not change the fact that the two signals arrive in phase. This is known as modulo phase shifting. Now consider the case where you are switched to the "0 degree" path and are located in a null from the combined pattern as seen from the aircraft, where the signals from the two antennas arrive out of phase. Flip the switch, and the differential path length is no longer out of phase, and the pattern is at a peak. This would allow the nulls and peaks to be moved dynamically. Now consider another pair of paths in series with the first 0/180 path, only the difference is 0 and 90 degrees. This is a two-bit phase shifter. By choosing between four states, a relative path length difference of either 0, 90, 180 or 270 can be selected. Likewise adding a 0/45 bit and creating a three-bit phase shifter would allow eight states, 0 through 315 degrees in 45 degree steps. This would allow flexibility in moving the beam peak dynamically. This is one half of the solution, the ability to move the peaks and nulls in the combined pattern. Effectively you would have a two element phased! array, which electronically steers the beam. Of course there are switches and digital electronics to make this happen. Either of the above methods solve the first problem, a means of switching or steering the antenna beam. There are two basic means of deciding how to do it, known as POINTING and TRACKING. Pointing means determining what direction you want the beam to be steered, and then setting the phase state to a known condition to accomplish that. Consider a satellite TV receiving dish. The installer gets information on the location of the satellite (latitude, longitude, altitude) and determines the location where the dish is to be installed (latitude, longitude, altitude). The pointing directions of azimuth and elevation are then calculated, and the antenna positioned to receive the signal. Tracking involves moving the receive antenna beam through it's range, monitoring the received power and choosing the direction of best signal reception. If either the receiver, the transmitter, or both are in motion, then the pointing or tracking becomes dynamic. The amount of relative motion determines how often sampling must occur and a corresponding change in selected antenna or beam will occur. Pointing requires that the location of all the VOR stations be stored in memory and used in the calculation of beam, and also that the aircraft position be continually updated . It's not a problem to do this with GPS, but this makes VOR dependent upon the GPS, and can't be implemented as one being a backup to the other. Besides, the reason someone is using the VOR is that they don't have GPS on board for whatever reason. To solve the second item, the box would have to either have a receiver that is tuned to the same channel as the radio, or to make use of the radio itself, as in reporting its power. The antenna is designed to receive all of the channels in the 108-118 MHz band, and each channel is 50 kHz wide. Therefore the tracking receiver has to be tuned to the same 50 kHz channel as the VOR receiver. If we wish to have the antenna switch automatically, we don't really want to have to manually tune it. The receiver implementation is starting to look a bit complicated. So what means is there of getting a power report from the VOR? It doesn't normally send out this type of signal. What does it report? Maybe there is a discreet signal from the VOR receiver to the OBS that causes the NAV flag to drop when out of range? This would be a natural and simple means of deciding to switch to the other antenna. With all the above in mind, it could be implemented as a tracking antenna with either switched or steered implementation. The switched implementation would have the two antennas into a SPDT coax switch. It can be arbitrarily set, and would toggle when the nav flag drops. If you are out of range of the VOR, this means it would be toggling back and forth. However, once the flag goes away, it will stay on the selected antenna, and only start to toggle when the flag drops. If the flag drops, and the antenna toggles, is must dwell long enough for the flag to disappear, or else it will never set to the proper antenna. The steered implementation would work much the same, but in this case, one antenna path (it doesn't matter which one) would have a one-bit phase shifter. The nav flag feedback would toggle the phase shifter. It may even work with a phase shifter of finer resolution (more than one bit), and just continue toggling through the phase states until the flag disappea! rs. The simpler the decision mechanism, the simpler the implementation. For what it's worth, Brian Cox, #478 +++ #6278 From: Brian Cox Subject: RE: [Bearhawk] antenna in tip? I see how a single wingtip antenna would be adequate for Localizer/GS. If you are crabbing into a left crosswind, it may blank a bit. Every antenna install is an opportunity for tradeoffs. I think that even though they fall short of perfection is OK. I will usually settle for "better than the next best alternative" as a good criteria. The fuselage truss should provide plenty of ground plane for the Comm antenna. One wavelength is over 90 inches, so the entire fuselage width of ~40" is less than half a wavelength. For a localized ground plane, I was suggesting something really lightweight stuck to the inside of the fabric, like wire screen, or a few radials of copper tape, thin wire, or metallized mylar. That was in reference to a question about the Christavia, and mounting the antenna a bit farther back than the truss. The neat thing is that you can install on the truss. If the radio performance is marginal, you can easily tweek it with these simple lightweight methods. As far as Comm antennas, I was out on the ramp at my local airport (Jeffco, CO - BJC) and saw a Grumman Cheetah. It had the comm antenna as the bent whip mounted on the belly straight between the main gear. It came back off the surface swept back at 45 degrees, then bent parallel to the ground. That is kind of similar to the optional location for the #2 nav from my earlier posting. Now I believe the gear legs are fiberglass, which is pretty friendly to RF. On the bearhawk, the shock struts come up in that location, and the balance of the gear legs would be more of a problem. Maybe a 2-3 feet aft of here would be a reasonable location. To get best GPS performance, go with the exterior mount puck style. If possible, use one with an integral active low noise amplifier. I suggested the puck because I haven't installed a panel mount GPS in anything I fly. The cost of good yoke mount ones are so inexpensive, and they work so well, that I can't bring myself to spend thousands for the panel versions, although there are some great ones available. I have the original Lowrance AirMap, which I've been using for about 5 years. It has a detachable patch antenna. I've never had a problem with reception on the glareshield of the 207, Mooney or 310. I'm now using a Compaq iPAQ. This is a Windows CE device that has Control Vision moving map software installed. After about a month of use, I'm still continually amazed at its performance. My GPS input to this is a Garmin 35. This is about the size of a computer mouse and encloses an antenna and GPS receiver. It takes 10-30 volt power from a cigarette lighter plug, ! and the serial output drives the iPAQ, along with also powering the device. Again, no reception problems. *** We interrupt this e-mail for a brief DISCLAIMER. I work for a company that puts legal cellphones in gen av aircraft. We have a network and dialup internet portal that can be used by computers with cellular modems. I don't intend to make this into a commercial for my company, but also want to let you know where I'm coming from on the GPS/computers/moving map angle.*** The glareshield mount is not the optimal antenna solution, it just happens to work very well for my application. It's also a solution that will fit most homebuilders needs IMHO. I'm assuming that the performance of these little computers is following Moore's Law (double processing speed and half cost every 18 months), whereas the panel mount will be the modern equivalent of an ADF sooner than we all would like. No knocks on the ADF, no knocks on the panel mount GPS, just an economic tradeoff. By the way, the iPAQ has the entire AOPA airport directory on it, and a weight and balance spreadsheet, synchs up to my desktop for my calendar and contacts list. It also has an MP3 player which I can patch to my intercom for music, a cellular modem, e-mail and web browser clients. And get this, I'm not even a gadget freak. I'd use this just for the moving map. Consider that the computer, GPS, yoke mount bracket, moving map software, desktop flight planner and 6 months of updates comes in at just about the same price as my original Lowrance. Also, the Lowrance has the serial data output as do most all of the handhelds and panel mounts. I really don't even need the Garmin 35 puck. I could use the Lowrance output, or any other GPS as the data source for the iPAQ through a serial cable. Here's the conceptual panel in my Bearhawk, VFR Airspeed Altimeter Turn and Bank (Old autopilot unit I have that runs on both vacuum/electric) VSI Compass No Attitude Indicator or Directional Gyro (leave panel space in case I change my mind) Comm #1 - VHF panel mount - whip antenna on top of fuselage Comm #2 - Sporty's handheld connected to belly mount bent whip Nav #1 - GPS moving map Nav #2 - spare old GPS handheld stowed Transponder/Encoder ELT No VOR or ADF No IFR planned for the Bearhawk. Brian Cox, #478 +++ #6279 From: Russ and Penny Erb Subject: RE: [Bearhawk] antenna in tip? Thanx Brian for another set of informative posts. I also consider that Localizer/GS require rather short range reception, so the antenna installation doesn't have to be as perfectly optimized. Not as short range as a marker beacon (practically anything will pick that up), but still short. As you may have gathered, I've decided to equip my Bearhawk for Night IFR. My primary mission is cross-country with the family (why I wanted 4 seats--if 2 would do I'd be typing this on the RV list probably). I've done these routes with a friend in a Cessna 180, and each trip at some point being able to file IFR kept us from being delayed. No thunderstorms or such nonsense, just clouds in the way. I won't even go into what avionics I would like to put in lest someone be all over me for violating the "Spirit of Bob" -- that would be the guy who's allergic to electricity. And as for apologizing for long posts--don't. I don't know what the supposed "magic" of short posts is. I think you'll find a long post full of meaty info will always be welcomed. As you (or someone) said recently, judge it on the "signal/noise" ratio. Remember that everyone still has the magic solution to longwinded drivel--the delete button. Just because someone sent you an e-mail doesn't mean you have to read every word. Besides, you're going to have to work a lot harder to approach the length of some of my long posts you'll find in the archives. I think the record holder is "So You Want To Be An Airplane Designer?" It's length was apparently so offensive that Del snagged it and put it in the FAQs so that people could continue to be offended for years to come. I think my posts follow the revised Waldmiller rule: they come out about pi times longer than I originally thought they would. Question to waste ponders on: Why is it that all pies have a circumference of 2*pi? Isn't that an extra pi? And why doesn't it last twice as long? (somebody stop me before I type another message!!!!) Russ Erb +++ #6289 From: zipppydoggg@y... Subject: Re: antenna in tip (continued) Excellent post, Do you think that a "Flying Lady" could be homebuilt? I'm attracted to the concept of one antenna for Comm and VOR. I agree with your vision of the equipment, VFR, except I think that a single VOR would be useful. Rob +++ #6294 From: Brian Cox Subject: RE: [Bearhawk] Re: antenna in tip (continued) It's possible to make the "flying lady" out of a wire "V" dipole on top of a post, and have the comm antenna buried inside the post. You don't want the post to be too tall. Normal swept comm antennas are about 20" long or so (a quarter wavelength is 23", but they usually have a lumped element matching circuit in the feed. It can also be shortened as a sleeved monopole, which is a monopole with a tube around it. This could be encapsulated in foam then glassed to form the body, with the vee attached to the top. Making an antenna in this manner will require a lot of tweeking, which could be an advantage or disadvantage. On the negative side, you would need the use of a network analyzer, or a spectrum analyzer with a reflection bridge and a tracking generator. Not the type of equipment normally available to the homebuilder, unless they work at a company that does antennas or radio products. This can also be an advantage. Since you are only making one antenna, it only has to be tweeked once. I have seen a couple of the flying lady's on ebay in the past. I've also seen a version that is a wire VOR on a post that would install in much the same fashion. This would be almost as handy. Like the flying lady, you could mount it above the cockpit, affording a much shorter coax run than a tail-mount VOR. In this case, the comm antenna would be separate, but there should be enough space to fit them both on the plane. I'll try to put together a paper with ideas on antennas and take some pictures, maybe I can submit them to the FAQ on e-groups. Or for inclusion in the CD, Version 3? I think I can find enough examples on the ramp at Jeffco to show all of the ones we discussed. Brian Cox, #478 +++ #6603 Date: Thu, 21 Jun 2001 23:15:41 -0000 From: bcox@ Subject: Antenna Locations Just a note to follow up on earlier antenna discussions. This month's Sport Aviation (June 2001) features the Murphy Super Rebel. The aerial photo on page 32 gives a really good look at the dual VHF comm, GPS, and ELT antenna installations. Anywhere in the wing area over the cabin would work pretty well for the comm, whether centered or offset to the side. The GPS position is pretty optimal for a good look at the upper sky. There is a picture on the cover that shows the aircraft belly. It's hard to see the transponder antenna, but the end of the right exhaust tip looks like it is pointing at the antenna from this perspective. Another picture on page 35 gives a better view of it, kind of centered between the gear and steps. I don't see any evidence of VOR, ADF, DME systems. The panel looks to have an audio selector/intercom, VHF comm, GPS/COM, and Transponder. Brian Cox, #478 +++ #6608 Date: Fri, 22 Jun 2001 15:09:06 -0000 From: zipppydoggg@ Subject: LED Position Lights? Has anyone thought of using an LED array for each position light? I was poking around looking for plans to build aircraft strobe lights. I think they are way too expensive. Along the way, I started looking at nav lights. At the same time, I was thinking of the new LED taillights seen on busses and trucks. I was thinking of the long life and low current draw of such a system. I'm planning on using LEDs for interior lighting; instrument, map, dome, etc. Yea, I know that a regular tail light bulb is very inexpensive and gives off a lot of light. I think I remember that Russ has cooked up his own home-brew position lights using NAPA parts (good idea). Does the FAA make any big deal about home made position lights? They wouldn't care (I don't think) about them for day VFR, but what about night flying. I've seen dozens of custom installations at airshows, surely these aircraft are cleared for night flying. When using regular tail light bulbs, is there any advantage to having a "dim" position and a "bright" position, using the tail light and brake light filaments respectively? Two filaments could mean less scrambling around to get the nav lights working prior to a night flight. Yea, I know the extra wire (plus swithch) adds weight. Rob "thinking in the distant future" Gaddy +++ #6609 Date: Fri, 22 Jun 2001 16:36:54 -0000 From: bcox@ Subject: Re: LED Position Lights? I have been scrounging parts on ebay and other web locations. There seem to be a lot of lights available for little cost. I picked up some NOS position lights for $5 each. They were manufactured over 40 years ago, but were in the original sealed packaging, some fibrous crepe paper outer with foil liner. They looked like new. One type was a really nice aluminum fitting, chromated, with the glass dome and bayonet style sockets for auto type bulbs. The other was similar, but with dual sockets inside. I bought enough to do the plane and have a set of spares. I'll figure it out as I build the wingtips. I also picked up a rotating beacon, mil surplus, for $15. Plan is to mount this either on the belly, like a Mooney, or on the aft fuselage. I'll have to plan the fitting when welding the fuselage. Brian Cox, #478 +++ #6611 Date: Fri, 22 Jun 2001 18:34:51 -0000 From: tallow_98@ Subject: Maule Diesel and Strobe site As for the lights ya'll have been discussing; check out www.misty.com/people/don for a very informative page on all kinds of lighting systems and sources that you build. Jimmy 501 +++ #6614 Date: Fri, 22 Jun 2001 18:31:53 -0400 From: Jim Ash ashcan@ Subject: Re: LED Position Lights? Are there official, lawyer approved colors for these lights, and do any LED's come in these specific spectrums? Jim Ash #387 +++ #6621 Date: Sat, 23 Jun 2001 19:31:36 pst From: "Russ Erb" erbman@ Subject: Re: LED Position Lights? I'm not using the two filament tail lights. I'm using the single filament white bulbs used for backup lights. Russ Erb #164, Edwards CA +++ #6622 Date: Sat, 23 Jun 2001 19:36:01 pst From: "Russ Erb" erbman@ Subject: Re: LED Position Lights? Position lights have a required angle that you be able to see them from. LEDs are typically very limited in their viewing angle. I doubt they would work unless you had a bunch pointed in different directions, and then I doubt they would be bright enough. At that point, it would be SIMPLER to use an incandescent bulb. Russ Erb +++ #6646 Date: Mon, 25 Jun 2001 14:15:22 -0000 From: zipppydoggg@ Subject: LED nav lights (continued) I check the FARs. The intensity and angles for the lights are given in the reg. The toughest requriements (I think) are for 40 candles per nav light straight ahead and the 110 degree angle. An array of several LEDs would be needed. This is where it could get expensive. The prices of LEDs varies widely, just like other electronic items. I didn't see a color requirement other than the general terms "green", "red", and "white". The multiple LEDs is really a strength of this system. One goes out and you don't have to stop flying right away as tge others continue to operate. As for the intensity, here in Phoenix, I've noted the use of LEDs in traffic control lights (red lights), and for tail lights on busses. They are plenty bright, even in the Phoenix sunshine. I've seen red, green, amber, and white. Rob "chewing the cud" Gaddy BH401 >>> 2mar02 #7686-9153 +++ #8729 From: Russ and Penny Erb Subject: RE: Another New Thread I'm going with 12 volt. 28 volt came about in large aircraft (military, commercial) as a weight savings ploy (higher voltage, smaller wires, less weight). My impression was that light plane manufacturers switched to 28 volt simply because "that's what you use in airplanes" with no real weight savings. With 12 volt you can use lights and accessories from the JC Whitney catalog or your favorite auto parts store. 28 volt items tend to have "airplane" stamped on them with the attendant inflated price. Worst of all, 28 volt requires two batteries, or a battery twice as big. That's a lot of weight (60 vs 30 lbs). I see no benefit whatsoever in using a 28 volt system in an airplane the size of the Bearhawk. A lot of the low current wires are sized by mechanical integrity, not current load. You can't really go below 22 or 24 gauge. You could save more weight by going on a diet. Them's my not terribly researched thoughts. Russ Erb +++ #8730 From: Ken Beanlands Subject: Re: Another New Thread I'd also have to agree with Budd. I learned more than I ever wanted to know about 24V systems when we had an overheating voltage regulator while crossing the Gulf in a 172 on floats. We landed in Pasadena with a dead battery on a Sunday morning only to find that it was a 24 V system. We had just picked up the airplane from the previous owner and hadn't been briefed on that little point. By a very lucky turn of events, the guy meeting us at the seaplane base lived next door to a mechanic for Canadian Helicopters that had access to a 24 V charger. I'd suggest sticking with 12/14 Volt Ken Beanlands B.Eng (Aerospace) +++ #8731 From: "Bruce A. Frank" Subject: Re: Another New Thread First 12 volt is 14 volt just as 24 is 28. I can see no good reason for using anything but 12 volt (13.8-14v). The 12 volt system, until recently, universal on automobiles for the last 40 years. All of the power using and generating stuff you need and want is available from automotive sources at bargain prices (relative to airplane prices). Even that "aviation" alternator on that 0-540 costing close to $500 can be replaced at PEP Boys or NAPA with an exact replica (I mean, even the part numbers match) for $80 to $150. There are virtually no alternatives with the 24/28 v. system. In theory higher voltage allows for smaller diameter wire to transmit the same amount of energy. On a military transport this might save you a couple a hundred pounds. On the Bearhawk maybe half a pound, if that! Are we measuring our wire diameters with our micrometers? I am actually installing oversize wire. Bruce A. Frank +++ #8739 From: "rodsmith52" Subject: Re: Another New Thread I agree with the rest, 12/14 volt system. 12 volt accessories are cheaper and more available. I highly recommend Bob Nuckolls book the Aeroelectric Connection for anyone about to wire their plane. You can read many of his articles on his web site, www.aeroelectric.com Rod Smith #246 +++ #8910 From: Erb Russell Maj DET 5 AFOTEC/DOB Subject: Static Wicks Today's AOPA e-Pilot brought up the issue of P-static, or precipitation static. This is the static charge that builds up when flying through moisture, and can cause problems with your avionics while IFR. If you plan to only fly VFR, then this probably isn't a problem. I do plan to fly IFR, so I need to at least consider this. My initial thoughts are a wick at each wingtip just outboard of the aileron (easier than trying to electrically bond the aileron or attach wicks to my aileron that is already covered) and wicks on outer parts of the elevators and rudders. I'm thinking I will also need bonding jumper wires between the rudder/elevator and the fin/stab. They are still uncovered, so I can add some tabs for the attachments. I throw this out to the group for discussion. Anyone else have any experience with P-static or static dischargers? Russ Erb +++ #8911 From: "Bruce A. Frank" Subject: Re: Static Wicks We are talking static electricity that has little difficulty jumping through contact points or materials in close proximity. I don't think you have to go to the trouble to electrically connecting these parts together. Install the wicks and the charge will come...er, well, in this case, Go! Bruce A. Frank +++ #8912 From: Bob Romanko Subject: RE: Static Wicks Ditto. There's enough metal there for the static to go through that strapping isn't an issue here. Static can happen in high humidity VFR conditions as well, but in most cases the flight times are so short that it's not as big of an issue in smaller aircraft, at least that's what I was taught WAY back when. I always wondered what The Spirit of St. Louis did for static. I'll have to ask my friend Lew Casey about that. Planter Bob +++ #8913 From: mprather@m...> Subject: Re: Static Wicks Lurker comment: One other issue with attaching anything with mass to control surfaces is balance. I believe the NTSB has attributed some flutter incidents on Bonanza tails to having too many coats of paint. I would guess that a static wick would way less than a coat of paint, but the majority of its mass is located far beyond the aft edge of the the aileron. Probably not a big deal at BH speeds, but if you are trying to balance the ailerons at all, it might be something to at least spend a moment to ponder. Matt- +++ #8914 From: Brian Cox Subject: RE: Static Wicks I throw this out to the group for discussion. Anyone else have any experience with P-static or static dischargers? Russ Erb #164, Edwards CA Hi Russ, I learned a few things about static wicks when I owned a Mooney. The forward fuselage is made of steel tubing and the skin is not stressed in this region. That's a legacy of the old M-20 Mooney that had fabric fuselage, wood wing and tail. I started experiencing intermittent compass errors on the order of 40 degrees. The first thing I tried was to overhaul the compass. After that, we took it out to the compass rose and it were able to swing it, experiencing no errors. A couple of days later, the error popped up when someone was doing instrument training. We then ordered a new compass, installed it, and again had a successful test on the ground. This still didn't fix the problem, and to further confuse the issue, the errors only occurred some of the time. I put out requests for help among MAPA and some of the better known Mooney specialists. Most folks were of the opinion that the steel cage had become magnetized over time. Many Mooney shops routinely degauss these cages. Another solution would have been a remote compass sensor in the tail with cockpit indicator (about $850 plus install). I could not get consistent advice on degaussing the cage. The most conservative advice was to fly it to a Mooney specialist and pay to have them degauss it. Middle of the road was to rent a degausser from them and have my mechanic do it. One shop said I could do it myself easily, and there was little difficulty or risk. Another shop said that I would have to remove not only all of my radios, but all electrical equipment from the panel, including fuel gauges, etc. Another source said I could go to a local TV repair shop and borrow one of their degaussers. Just place it in close proximity to the steel tubes, then pull the trigger. Hold the trigger down, remove the degausser from the plane, get a fair distance away, then let go of the trigger. The main problem I had was the inconsistency in all this advice, so I just didn't feel good about trying to degauss the frame. I quizzed the pilots about the prevailing conditions when they experienced compass error, and concluded that it didn't occur on dry days. On a hunch, I decided to buy the static wick kit from Mooney. It was about $350, and took a couple of hours for my shop to install. There were 15 wicks (!), three each on the ailerons, L&R elevator and rudder. These were the plastic jet style, about 3-4" long. Once installed, the compass errors went away. In contrast I had a T207 that had one wick on each surface instead of three. These were the ones that look like a cord. They seemed to work OK. The 310 doesn't have any on the ailerons, wings or tip tanks. There are a couple on the elevator and rudder. I don't seem to have any P-static problems in it either. I'll probably copy this setup on the Bearhawk. Brian Cox, #478 +++ #8916 From: Bob Romanko Subject: RE: Static Wicks No, but he had fuel, and someone had to touch the plane when he landed. Planter Bob +++ #8917 From: Russ and Penny Erb Subject: RE: Static Wicks I mentioned the jumper wires because I'm not sure of the electrical conductivity through hinges that are filled with grease. Yes there may be some, but a small jumper would provide a reliable connection. As for the question of balance, my elevator has been balanced with my best estimate of fabric weight. I can check it after adding the wicks (before covering) and if it appears to be a problem, I'll add some more balance weight. As for the ailerons (which tend to be more of the flutter problem because of any flexibility in the wing), that's another reason why I said I'd mount in on the tip on the non-moving part. Based on the response so far, it's sounding like static wicks are a good idea for those of us planning to fly IFR. Russ Erb +++ #8922 From: Matt Prather Subject: Re: Static Wicks Modern tires (at least) have a significant amount of carbon added (coloring them black) to make them (I believe) UV stable, and so they are fairly conductive. The reason that cars are a safe place to be in an electrical storm is not because the tires are insulators, but because the metal shell of the car body makes a Faraday cage to conduct electricity instead of allowing your body to do the dirty work. Fuel won't care about the charge buildup as long as its not exposed to a spark. Everything has to be at some potential (including the gasoline). Having a large potential (voltage) is not in itself dangerous (think bird on a powerline - its voltage is varying by the line voltage at 60Hz/120Hz). Making something not designed to be conductor cary current is not good, and exposing volatile hydrocarbons to spark is not good. Also, the Spirit' has a tailskid. It would be still interesting to know if static was something they were thinking about at that point. MAP +++ #9105 From: Russ and Penny Erb Subject: The Last (?) Word on Static Wicks For those of you planning IFR and needing a source of static wicks, I recommend http://www.cessnaparts.com (Hill Aircraft) Part number C592001-0201 $16.65 each Keep that part number because you can't order from these guys without it. The comparable Aircraft Spruce price is $49.30. The cheapest one Spruce has is $34.95. It seems really odd that a part sold as a "certified airplane part" costs significantly less than the same thing in the Spruce catalog. Russ Erb >>> 4sep02 #9154-11297 +++ #9342 From: "Pat Fagan" pfflyerz@c... Subject: rocker switches update Remember how excited I was a while back about Carling rocker switch breakers? Well, forget about them. You can't order from the factory and the closest authorized supplier is an hours drive from me. I decided to go with the Potter Brumfields, but they are so ugly I couldn't go through with it. I finally made the drive to a Carling dealer yesterday. The part number takes some real study, but they allow you to customize every feature of the breaker to your desires. The rep said Carling has a 5 switch minimum and it takes 6 to 7 weeks to get them. I wanted 5 so I said "Let's do it". When she tallied up my bill it came to $420! Carling required a minimum of 5 for each style & amperage. Needless to say, I am rethinking my switch requirements. My wife and I have started covering #232. We have covered both doors, the cargo doors, trim tabs, and the horizontal tails. It is getting easier as we get more experience. I also made an extra set of "patroller" doors that turned out pretty nice. I will post a picture whenever I get one developed. +++ #9922 From: "Bruce A. Frank" Subject: Strobes and Landing lights Don't know how many of you keep track of the newsgroup , well, I know a few of you do. Richard Riley posted these links a few days ago and after going to the web site and the dealer's sites I find this worth passing along. The following is a copy of what I have passed along to others. Others who are very happy to find this stuff. >These are the leads for lighting. The Matronics link takes you to a >post about getting the strobes. Go read that first. The link from that >text is to: > >http://www.strobe.com > > The Nova Strobe (that looks just like the Whelan). If you follow the > dealer links from Nova's page you will see that the dealers carry both > the Nova and the industrial Whelan. One dealer that I saw had a sale > on the Whelan package (power supply, lights and cable) but you can go > as high as 90 watts with the Nova brand. > > Click on "ordering" on the left of the page and three dealers are >listed. 'Strobes and More' seemed to have the best price. I looked at >exactly the same Whelan Aviation product a while back and the package >with four strobes was over $800. The equivalent Nova package cost about >$255,. > > Now if you want an HID (High Intensity Discharge--xenon bulb...no >filament...bright as a continuous strobe ) landing light, the Galaxy >Mall link is the place to go. > >Bruce >richard@riley.com wrote: >> >> Pheonix Micro Light has drop in replacement HID PAR-36 and 46, bulb >> and ballast in the $300 range. They aren't listed on the website, >> but they do have them if you call and ask. >> >> http://www.galaxymall.com/auto/microlite/products.html >> >> For strobes, there's a great article on the Matronics RV list archive >> (sorry for the long URL) > http://www.matronics.com/searching/getmsg_script.cgi?INDEX=102641277?KEYS=nova?LISTNAME=RV?HITNUMBER=36?SERIAL=23112628000? >> >>> 20may03 #11298-18250 +++ 11635 From: Russ and Penny Erb Subject: RE: EAA 1000 table suggestions > Speaking of the leading edge landing light, I've been meaning to ask > you if there are going to be pictures and/or drawings of it on the > next version of the CD (which I'm actually planning on buying this > time around). Yep, just like they were on Version 2! Please take note of the caution that comes with it--namely that I have found several types of smaller bulbs that are suitable for use. I'm locked in now, but if you use a smaller bulb you can do it without having to move any ribs. I'm in the final proofing stage of Version 3, so look for an announcement "soon". Russ Erb +++ #14118 From: "fourthwedge" Subject: Avionics Wiring Stolen directly off the RV List. Looks pretty good to a somebody who has trouble getting a flashlight to work right. Dave Subject: Avionics wiring From: Stephen Johnson (spjohnsn@i...) --> RV-List message posted by: "Stephen Johnson" There is a completely new approach to avionics wiring that has been developed by a company in Utah. They gave a presentation to our local RV group a couple of months ago. I'm a little surprised that there hasn't been much on the list about this, so I thought I'd post something so that anybody at the stage of avionics installation would at least take a look at this approach. The company is Approach Systems and their web site is: www.approach-systems.com They basically have a modular system with a multilayer circuit board as a hub with pre-wired cables to the boxes. This offers big advantages in noise immunity, time savings and trouble shooting. I'm a retired EE and I spent some 30 years knocking around electronics labs, and I have to personally recommend this way to go. I have absolutely no connection with this company. Happy building. Steve Johnson +++ #14122 From: Budd Davisson Subject: Re: Avionics Wiring I'm quite familiar with the Approach system and we're going to use it where we can. It's a true plug and play operation and the most complex thing you have to do is run a power to the module. I highly recommend it to folks like me who keep caps on all of the power outlets in our house in the belief that if we don't the electricity will flow out and puddle on the floor. bd +++ #14128 From: "rodsmith52" Subject: Re: Avionics Wiring/Subaru engine I just looked at this setup on a local RV-7 and thought it was a great idea. He has a Blue Mountain EFIS and UPS GPS/Com and UPS transponder. I think he said the hub and harnesses cost him about a $1000, which is probably less than an avionics shop would have charged him. He said he could have wired everything himself but one cold solder joint and he would be looking for the problem a long time. Rod Smith +++ #14635 From: Benton Holzwarth Subject: RAH vs. Exp Avionics > What is RAH? There is also a YahooGroups list for avionics -- "ExperimentalAvionics ". I've only tuned in briefly there, so won't comment on the quality of the discussion. Benton +++ #15432 From: Russ and Penny Erb Subject: RE: Autopilot Selection > Russ (and any others), which autopilot are you intending to install? > The Navaid and TruTrak are popular autopilots with the RV crowd. > They are inexpensive (compared to the S-TEC line). I will be installing the S-Tec System 30. I wanted a two-axis autopilot, and my experience has been with an S-Tec autopilot in a friend's C-180. The servo mount shown on the CD is for the S-Tec servo. I don't have a servo yet, but the fine folks at S-Tec sent me the drawing of the external dimensions so that I could design for it. As far as I know, the Navaid is only a wing leveler, and possible a nav-tracker. No altitude hold function. If someone knows better, feel free to correct me. Russ Erb +++ #15625 From: Bob Romanko Subject: The Case for Electrical Allergies You know....I've been thinking...... Is it really worth it to have any circuits other than the one from the mags to the end of the plugs? There are a lot of advantages to bagging electronics.... 1. Less weight 2. Less cost of ownership (I got over $6,000 in my 175 radios already) 3. Less complexity 4. Less to go wrong 5. Less to have stolen 6. Less chance of fire 7. Easily replaced with a handheld nav/com and gps I could probably add more, but you're getting the idea. With what I've been throwing into 42Echo lately, I'm strongly considering having a MINIMAL panel on my Bearhawk. In fact, handproping is starting to make a lot of sense. I don't fly at night, have a handheld GPS and nav/com, and frankly can keep out of airspace where I'd need a transponder. If I were going on a long xcountry I'd probably charge a small 12V battery and throw it in the baggage area and hook it up to a wire that terminates on the panel in two lighter sockets rather than pack AA batteries. I don't know....maybe I'm just tired of feeling like I'm gradually purchasing an avionics shop...... Planter "Reconsidering Getting My Instrument Rating" Bob +++ #15637 From: Russ and Penny Erb Subject: RE: The Case for Electrical Allergies Bagging electronics is just fine IF: 1. You don't want to go anywhere, and 2. You don't mind waiting to go there. i.e. "Time to spare, go by air" As for #164, I'll absorb the weight and expense for the promise of being able to keep reasonably close to schedule. Remember if you approach it right, you may not have to give all of your money to the avionics shop--there will be more things you can do yourself and do it better than the flunky who's not getting paid that much. Snap out of it and listen to Del. Russ Erb +++ #15662 From: Ken Beanlands Subject: Re: The Case for Electrical Allergies That's similar to my phylosophy on the Christavia although I will have a battery, starter and altenator. What I've geared the panel up with is: Yaesu handheld radio $350 New Garmin GPS III GPS $850 New FlightCom 2-place intercom $125 Salvaged Gimes 2-flasher red strobe pack (free except for $50 to avionics shop to convert from 24 V to 12V and bench check) $50 Westach 3-1/8" Tach ~$100 Westach 2-1/4" ammeter/voltmeter combo ~$100 4 x Westach 2-1/4" CHT/EGT combo ~$750 Mitchel 2-1/4" Oil Pressure ~$75 Mitchel 2-1/4" Oil Temp ~$75 Salvaged 3-1/4" Altimeter (crash investigators disassembled it, avionics shop put it back together and recertified) $120 New 3-1/4" ASI (traded for salvaged unit) Free Salvaged VSI 3-1/4" Free Salvaged T&B 3-1/4" Free Compass $125 Fuel Gauge, sight $20 Breakers/switches $150 Mixture/Carb/Cabin heat controls $225 Ameriking ELT $300 Total for the panel: $3415 CAD, $2200 USD. Biggest ticket items are the 4 CHT/EGT gauges (still a lot cheaper than an engine analyzer) and the GPS. There is no reason why you couldn't match this on the BH with a little scrounging. You really have to watch what you scrounge though. I ended up with a functioning ELT, but the replacement batteries were half of what the Ameriking ELT costs, and the Ameriking uses D-cell alkaline batteries. The best source for inexpensive instruments and avionics are the local avionics shops. They typically have some units sitting around that you can buy that come bench tested and ready to roll. If you don't mind older equipment,this is a good way to go. It is nice to be able to use the electric instruments. I have a combination mechanical oil pressure/temp gauge but I was a little concerned about running an oil line from the engine back through the firewall and under the fuel tank. Besides, the temp probe wouldn't fit the Franklin. I'll be holding on to that one for the BH. The little John Deere altenator seems to be the best compromise between a full electrical system and none at all. You can get away without a battery or starter, and just run the altenator. Ken Beanlands B.Eng (Aerospace) +++ #15665 From: Ken Beanlands Subject: RE: The Case for Electrical Allergies The same arguement can be made for buildign a plane and installing a full IFR panel. It's fine to install if: 1. You don't want to finish the project 2. You don't mind waiting to finish it. I've heard it said that hafl the build time of a typical aircraft is taken up by installing systems between the panel and nose. The less you have there, the quicker it goes and the less likely you are to become frusturated with the project and give it up. There are a lot of projects listed for sale as 90% complete. Typically, they are just needing the panel installed. My approach is to start as simple as possible with no panel mount avionica and as simple a panel as possible; no vacuum gyros, no electronic engine analyzer, no panel mount avionics stack, no lighting (except a pair of strobes), etc. However, I have provisioned the plane with the instrument holes for the vacuum gauges and with 2 radilo stacks, one housing a glove box and the other will provide a mount for the GPS and handheld. If I find that sort of flying limiting, then I'll add the luxury items later. This will allow me to get flying this year (accounting for both time and available funds). Otherwise, I'd be at it at least 1-2 more years. Ken Beanlands B.Eng (Aerospace) +++ #15711 From: "Mark Conover" Subject: Wing Tip Landing Lights I came across this link in another e-group: http://www.creativair.com/mr75/index.htm It's a new, inexpensive ($150.00 per pair) landing light kit. Uses MIR-16 75 watt halogen bulbs. Originally designed for RV tips. Seems it could be modified for B'hawk purposes. Mark Conover +++ #15713 From: Russ and Penny Erb Subject: RE: Wing Tip Landing Lights Yes, that could probably be adapted to Bearhawk tips. Note that the strobes are blocked to the rear, so an additional rear facing strobe will be required. Russ Erb +++ #15714 From: "Mark Conover" Subject: Re: Wing Tip Landing Lights I noticed that too. The kit doesn't include the nav light/strobe unit that you see in the example. Any concerns over the amount of heat generated by the halogen bulb? Apparently, it is designed to be projected backward. Mark Conover +++ #15716 From: Del Rawlins Subject: RE: Wing Tip Landing Lights > Yes, that could probably be adapted to Bearhawk tips. Note that the > strobes are blocked to the rear, so an additional rear facing strobe > will be required. Or another way of looking at it, the Bearhawk tips could probably be adapted to fit those lights, if you were planning to make your own tips anyway. It might be necessary to change Bob's tip design slightly, if you weren't planning to do that anyway. I hadn't decided yet whether to go with a cowl mounted light or between the wing ribs like Russ, so this is a good third option to consider. Particularly since I was thinking about doing something similar just for the position lights. -- Del Rawlins +++ #15727 From: "Mark Conover" Subject: Re: Autopilot Selection (long) All my cash is heading south to Mexico (or at least Arizona), so I need to find a less expensive method of reducing the work load during long trips and enroute IFR. All that I've learned from others makes me feel pretty confident that the Navaid autopilot will do the job. Based on a fairly extensive Usenet search, I found a lot of current users of the device who are happy with the performance of the autopilot. Part of the reason for that is having a low expectation, as the Navaid people make no pretense that this unit is of the same quality as the S-TEC models. The Navaid AP-1 provides both a simple wing-leveler mode, as well as a Nav Trak mode (wired to CDI deflection outputs or GPS). I think there is even a track-intercept mode available. Not bad for $1,300. While this device is not promoted as being for IFR, it is clear that many people are doing so. By no means should it be used for shooting an approach. But, in a busy one-person cockpit, I wouldn't mind having it available. My old 182 had a Pathfinder autopilot with similar capabilities, though that ancient device was less precise than the Navaid( if user-reports are to be believed). Here in the land of IMC (Puget Sound), I would mainly hand-fly in IMC. But, once in a while, I'd off-load maintaining course to the autopilot. Since the Pathfinder was almost thirty years old, it took a lot of testing the unit during VFR before I grew comfortable with it in IMC. Same would be true of the Navaid. Again, only at altitude, not during an approach. And what about altitude hold for the pilot of modest means? Well, I found an intriguing reference to a do-it-yourself alt-hold device called the EZTrim: http://hometown.aol.com/ccady/eztrim4.htm This pressure-transducer-based unit interfaces electronically to a MAC-type servo that is driving (in our case) the elevator trim horn. I happen to already already have a MAC servo, and intend to use it. The brains of the EZTrim device is a plain old Parallax Basic Stamp microcontroller. For a while, the developer of EZTrim was selling the units. He has since decided that he was spending too much time doing that. Now all supporting information (PCB layout, parts list, and Basic source code) can be downloaded at no cost. Those of us having microcontroller develoment experience would find this project very straight-forward. I'll be concentrating on my wings for another year or two, and then on populating the Avipro fuselage with parts. But after that, I've got to try this. Mark Conover, #502 +++ #17511 From: "zipppydoggg" Subject: 12 or 24 Volts I don't remember any discussion about using a 12 volt or 24 volt system in the BH. I guess most engines have a 12 volt alternator and starter, which essentially settles the question. I anyone using anything different? I could go either way for the same money. Rob "what would I do at work except think about these things?" Gaddy BH401 +++ #17513 From: Bob Romanko Subject: RE: 12 or 24 Volts Tony Bingelis, God rest is soul, wrote a great article on this back in December, '89: http://members.eaa.org/home/homebuilders/authors/bingelis/12%20Volts%20vs.%2 024%20Volts.html That's in the member's section of the EAA website. If that URL wrapped on you, don't forget to cut/paste that sucker back together in your browser's address window. Planter Bob p.s. The answer is 12 Volts (grin) +++ #17516 From: Ken Beanlands Subject: Re: 12 or 24 Volts If you are buying all new equipment, then it totally does not matter which way tyou go. 24 V will typically run a little cooler which may be critical on a fully populated IFR stach and especially with a remote avionics bay, but for something like the BH, it wouldn't really matter. However, if you plan on using used equipment, then 12V is far more common and readily available. If a device is available in only one voltage type, it will usually be 12V. Finally, if you ever end up with an overheating VR resulting in a dead battery on the shore of a Newfoundland lake on a Sunday morning, you may find that it's a lot harder to get a boost or a recharge for a 24 V system than a 12V. If you're lucky, the chief engineer for Canadian Helicopters is around and willing to help ;-) Ken Beanlands B.Eng (Aerospace) +++ #17519 From: "Bruce A. Frank" Subject: Re: 12 or 24 Volts I have looked at a lot of voltage systems, particularly since some automotive applications are going to 24 and even 36 to 48 in some vehicles. Twelve volt is still the least expensive both from the equipment needed to generate and regulate it to the cost of the instruments and radios that run on it...at least in my research. Higher voltage alternators, regulators and starters are smaller and thus lighter, but if I were really concerned about that few pounds of weight I'd get my act together and lose 60 lbs of body fat. Bruce A. Frank +++ $Id: 2.5.2-Systems-Electrical,v 1.15 2003/05/22 03:33:30 bentonh Exp $