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Engine Mount, Gear Legs |
Bleeding Brakes For the archives ... Today we filled the brake system on OLE No. 1.. Did it from the bottom up and sure enough the dern brake cylinders held a pocket of air. We then pressurized the system from the top down and sure nuff the air was blown out the bottom and now OLE No. 1 has brakes. Hard brakes!!! Next time I do it from the top down first.. BTW make sure the cylinder is extended to the max.. Not a problem with the internal spring type.. Good luck... Larry #001 Hi Fellas: Is there something unique to the master cylinders on the Rocket that I can't get Randy- I bleed the brakes from the wheel up to the reservoir. I unhook the lower bolt of Hey Randy: I will suggest that there is still air in there somehwere. DUH!! Like you didn't know that...sometimes I have an amazing grasp of the obvious.The mast cyls have a port or valve of sorts in them to allow the system to hold about 1-2PSI on the slave cyls. You have to grab the brake pedals and pull the tops aft to open this port/valve during the bleeding process. We don't find it necessary to gyrate with the mast cyls to get a firm pedal-- just run enough fluid thru to get all the air out. Again, DUH!! Like Tom said, we fill from the bottom here too.Cheers Mark If I lay the brake cylinder horizontal and bleed the brakes, is that sufficient to get the air out? Because that's what I've done! Randy It should be up from horizontal, not much, a couple of inches should do. Tom Martin Fairlea Field Randy I read tom and mark's reply and did precisely what they said with Matco, I know you have Grove. Guess what I had to fill from the top to burp the air using a fancy bleed rig from Spruce. Bled from the bottom I always had air. Perhaps the initial fill from the bottom was beneficial in making most of the air going away. I saw you made your own bleed rig, does it introduce air? BTW I have individual master cylinders as you do. Pedals are pleasingly hard now. Best Howard Since the master cylinders are upside down another way to really ensure there is no air in the system is to pump a large volume of fluid through the brake lines, and at the same time pump the brake pedals. Its pretty easy to fashion something to do that. You take a can of some sort, fill it with whatever brake fluid you are using, and put a quick connect air fitting on the can on top, and another one for the fluid on the side at the bottom. Connect that to the bleeder at the caliper. Take a hose and attach it to the resevoir, run the hose to a clean bucket. Turn the air on the same time you have someone in the front pumping the brakes. Voila, your brakes get bled in about 1 minute without any disassembly. You can watch the bubbles flowing thru the clear lines. I've seen a few RV-4 guys do this and it works well, you don't have to fool with any disassembly. Regards, Bob Thanks for all the responses to my problem. So far, everything that has been How does your recirculating thingie purge air out of itself? My guess is that may be your problem...having it open-loop and not recirculating and really blowing fluid thru the system is how Jim W. and those guys do it. If we had more room in the footwells the better solution would be to turn the cylinders right side up, like the RV-6. Regards, Bob Very easy. The return line is plumbed back to the remote resevoir and the air simply bubbles to the top of the resevoir. Everything is made out of clear plastic and clear tubing so you can see what is going on. I know there's air somewhere. I just got to find it. Randy Thats how I do it with the bulb thingie from spruce, run fluid through, not recirclulate, and be very careful not to introduce air all from the top after doing the bottom first. The compressed air drive through system sounds good too. I think your technique is at fault Randy,,,,,,,but what? You are covering all the what ifs it seems. Call mark and pester him, take an aspirin. Good Luck Howard Randy, I had the same problem with my brakes, what I did was hook up a an fitting to the top of the resevior so I could attach a hose and a large funnel that held about a gallon of brake fluid and let the fluid run through the system about 4 to 5 times while working the brakes. Fixed the problem. Sounds like the recirculating thing might be the same thing but may not have the volume needed to push the air out. Just a thought. John Wach For it to work you really have to blast fluid through the system. As John says volume is the key. You can make this whole setup out of an empty bucket for next to nothing. Regards, Bob I agree. We found that the tiniest amount of air introduced into the inlet fitting (either top or bottom) negated success. Once we found the formula, we were done in 5 minutes. Problem is, it took us 90 minutes to find the formula. Good thing we knew where the beer was beforehand...Cheers Mark PS Bob -- which auto trans fluid did you recommend again? What was the SPEC #? Mobil 1 Synthetic ATF. Works good in your car too. Fortunately I had two quarts of that stuff on the shelf. In Allison transmissions you can use either hydralic fluid or ATF, that leads me to think its the same damn thing or pretty close to Aeroshell 31. Now if we can figure out a way to use beer instead of brake fluid... Regards, Bob Regarding brakes, is anyone running individual reservoirs on each master cylinder, or will this not work too well since the cylinders are upside down, and the reservoir would be low, and have a tendency to 'overflow' as the airplane sat and the master cylinder drained into it? I've seen this on other airplanes with the cylinders right side up, and it is a very clean installation. Thanks, Scott Roth #93 One thing to be careful about with any system, but particularly a closed or recirculating system, is small bubbles. If any turbulance is introduced in system (such as pouring into container), it takes a long time for the tiny bubbles (no relation to dancer) to come out of solution. There are also small, invisible bubbles in solution. These will come out with time. These are quite devious and love to collect in the worst places and tend to lodge there. The top (bottom) of our inverted cylinders are a great place. Tapping on them helps to dislodge. It is best to let fluid sit for sometime before circulating and bleeding. Bleeding from top with pressure bleeder seems to work best for me, but does not seem to last. My RV-4 seemed to be the same way. Just learned to live with weak brakes. I'll guaranty that they are strong enough to put you on your nose if applied too hard while in motion. GWBM I have it and it is working just fine. I used the units at the top of the page on the right, part number A-700: http://www.wicksaircraft.com/gotopage.php?page=156 I added a 90 deg fitting at the outlet to go into the side of the master cylinder so maybe the A-600 would be better since it has the 90 built in. scot Okay, break out the beer. I've finally achieved success. It was a combination of many of the ideas I received today. By really pushing the fluid through and vigoriously pumping the brakes with the cylinder turned horizontal, I was finally able to coax the final few bubbles out of the system. The brakes are firm now, but I think Tom had a good point, those littel bubbles may collect later. We'll see. Thanks to everyone who offered up suggestions. Now it's back to the windshield. Regards, Randy #95
Matco is smaller and fits nicely under the F-1 wheel pants with no extra > fitting. The Grove required some major fiberglass work on the wheel pants > (kit #79), which resulted in a large bump-out to accommodate the extra size > of the assembly. I didn't like that. Again, this is a for-what-it's-worth. Right now I have two F-1s sitting in my hangar. One has Grove brakes (the new one) and one has Matco (mine). I have only taxi tested the new one, but have around 110 hours on mine with Matco brakes. Here are my comparisons. I like everything that Grove sells. Its good quality stuff, you can't go wrong with it. I also like Marco. I can tell little or no difference in stopping or holding power of the two systems. Matco is smaller and fits nicely under the F-1 wheel pants with no extra fitting. The Grove required some major fiberglass work on the wheel pants (kit #79), which resulted in a large bump-out to accommodate the extra size of the assembly. I didn't like that. The reason I grew fond of the Marco system is ease of wheel removal. It is essentially the same as the Cleveland system, except there are three hardened bolts that hold the disc to the wheel. Remove those and the wheel easily slips off followed by the disc without dissembling the brake (as you do on the Cleveland). I have had to remove mine several times adding shims to the gear legs and changing tires. My recommendation would be to use the Matco if you have them. Once again Rocketeers, "What ever lights your Rocket". Jim Cash Jim My concern with Matco is grass strip ops when there is a little mud that can get flung up and into the area behind the brake disc.Do you have any comments about that?I will be putting a bulkhead behind the wheels to keep crap out of the aft portion of the W/pants.I have had no probs in that environment and my Cleveland wheel/brake combo. Thanks!! Bill A Hey Bill, I installed a bulkhead behind the wheel in my wheel pants, and it really makes a difference in keeping them free of debris. I think it added strength also. Along the same lines, I added two floating horizontal ribs to my wingtips. Mark's fiberglass lay-ups are thin, yet strong and light. However, those additions have kept me trouble free for the first 100+ hours, and the wingtips maintain their shape out to 260 MPH (that's the max I have flown the airplane). I can't really see any measurable difference between the Cleveland's (which I have always used) and the Matco, except I had rather work with Matco. I have not had this set in the grass that much, but I did with the Cleveland's with no problem. I just don't think it is a big thing. The Groves are a big brake system. The wheel pant on the new F-1 has a big bulge on the inside to accomadate the size. I guess if you subscribe to the theory that bigger is better, they may be better. (HA) I don't use the brakes any more than necessary anyway, and have found the Matco's to be very acceptable for my application. Working with the company has been positive also. Jim Jim Winings tells me his Matco wheels are 1/2" narrower than Cleveland's...FWIW. Probably doesn't help the rigidity of the tire. Jim, if you flipped the brake caliper to be on the front side of the axle, would there be more room in there for it? Bob Bob, I never considered it. I would have to go out, pull the wheel pants and take a look. Jim Hey Fellas: Just got off the phone with Robbie Grove. He had heard about this particular post, and asked me to clarify (turns out the wheel AND pant are his designs, and are intended to be used together). Here goes: We designed a new inner pant bracket and torque plate to allow the Grove calipers to be rotated to appear to be directly behind the axle centerline, thus allowing more room for the caliper to be inside the pant with no additional fiberglass mods. We set up a mount with legs & wheels/tires on the bench here to see about the fit of all the parts (and to see what dims were needed for the outer pant attach fitting), and we had no problems getting all the parts inside the pant. When you start fitting the pants over the Grove wheels, you will use the outer attach point to set the tire/wheelpant centerline relationship -- the tire DOES NOT run in the center of the pant. The tire is set towards the outside of the pant, so that you will NOT have to make a bump for the caliper. It sounds to me that #79 had the pants installed with the tire centered in the pant, and this would surely necessitate a bump for caliper clearance. This type of install is not wrong, just different. Probably needed some mods to the lower intersection fairing too,and a fairly large bushing, or offset, for the outer attach point, as would be used on the Van's pressure recovery style pants. I'm not sure I can get assembly photos of this into V2.24 of the manual, unless I delay the production date of that upgrade...we're not that far along with the F1 we're building here to take those photos, and the initial R&D on the bracket install didn't look very photogenic, if you get my drift. Photos be in V2.25 for sure. If Robbie will supply some CAD files of the wheel assy, it could be that I can produce a CAD section view of the wheel/axle/tire/pant assy, posssibly enlightening some of the builders. Maybe I can insert an exploded view too, useful as reference in changing brake pads and general servicing of the wheel assembly.... Happy New Year to you all! Mark To help clarify the comment on the Kit #79 Grove brake installation I checked with Art, who installed them. He used Van's wheel pants on that airplane which probably explains the difference. I personally much perfer Mark's wheel pants, which are installed on my F-1. The bulge on these pants is very pronounced, so if anyone else is contemplating using Van's, the first post would apply. Jim Brake Lines ran solid all the way from the firewall to the caliper, with a loop near the caliper for flexing. The line runs inside a groove in the wooden stiffeners I put on recently. No clamps on the gear leg whatsoever. Wellllll....it may happen that you could pull the flare off the solid line by flexing it to change pads etc. Just watch it, and you should be OK. The next owner might not be so savvy about this particular aspect of servicing that ship.... The groove in the dampers is exactly how we did it. Plastic line: We have a heavier ship, which lands a bit faster, and thus we use the brakes more/harder... which causes more heat...and the plastic line WILL flow a bit if you get it hot enough...which will allow a leak to start at the fitting...etc. So, it may be suggested that the brake line install is not the place to use non aircraft materials and techniques. Example: the BEST nylon tubing -- 2500 psi -- is UNUSABLE at temps above 280F. If you think you'll never get your brake system that hot, I have some ocean front property in Kansas I'll sell you. Remember: you sign a statement when you get your ship signed off, saying that you built it to plans/manual, with the noted exceptions. I'd recommend noting any changes (brake line not built according to manual, etc), so your insurance company can't come back and deny a claim due to paperwork innacuracies. Especially if you run off the runway due to a brake line failure -- don't think they don't look for this stuff.Be careful! Mark I have replaced 4 broken aluminum brake lines, 2 on my older RV-4 at about 400 hours and 2 on a HRII at about 200 hours. We replaced these with plastic. The HRII now has about 600 hours. I am using plastic lines on my present RV-4 with 1150 hours with no problems. My F-1 has plastic lines. All trucks today have plastic air brake lines. We have no trouble compared to when we used copper lines. My 2 cents worth. Jim #34 We were talking about brake lines a few days ago. I had concerns. I hate when my airplane won't stop. I had planned to use solid aluminum tubing from the firewall to the caliper as is done on other RVs, etc. I've never been wild about the Nylaseal stuff due to heat softening concerns so I didn't want to use it. Then Jim Winings and Mark convinced me to take a look at using something other than solid aluminum lines. They explained to me that the world would end, the sky would fall, etc, and my brakelines would break... blah, blah, blah :-) Seriously though, I value their opinions and the change I'm gonna make is easy and cheap. Here's what I found. Maybe this will cause others to rip out their finished brake lines and set themselves back a week. LOL Aeroquip makes a teflon lined S/S hose, FC807-4, that is equivalent to their teflon lined S/S brake (racing)hose. They told me so on the phone, although they really can't say that. The difference is that FC807-4 is $1.20/ft and the racing hose is $4/ft. They use the same fittings. http://aeroquip.murdockindustrial.com/hoseselector.htm One supplier. In Ohio. The kid was quite helpful. https://fluidpower.eaton.com/intradoc/groups/public/documents/prod_bulletins/ja8 86.pdf Specs for the hose. In a nutshell, -100 to 450 degrees, operating pressure 3000 psi, and burst at 12,000 psi. 0.06 pounds per ft I bought enough line to and fittings to make every part of the brake line, both sides, and it was only about $70. Cheap. And the fittings are easy to install and reusable. I'll probably use this same hose elsewhere under the cowling for oil and fuel lines. For gosh sakes, somebody tell me now if this is a bad idea. Vince I'm told teflon hoses have no life limit, as does the normal Aeroquip stuff we use. Sounds like a great alternative. Carry on! Mark
I put mine to the left of center to leave the large central area free for ignition modules etc. No regrets. Warmest Regards, Bob Gross I'm ready to mount the brake master cylinder and run the tubing/hoses to complete the brake installation. How far up on the firewall? Brake /Parking Has anyone installed a park brake on the bird? Don't need it---more weight. Jim I installed the Cleveland unit, P/N CWB60-5 from the Wicks catalog. I >mounted it to the underside of a DON`T they cause PROBLEMS you haven`t even thought of yet!!!! Bill I am not sure you can make thom fail-safe. I took them off my Great Lakes as there has been more than one I think vans has a setup for their series that should work...Eric Install the cyls as shown in the manual please, tho some say that the opposite direction facilitates Engine Mount If I'm not mistaken, my O-540-B2B5 has the wrong size engine mount ears on Guys, You all have noticed the bolt on engine mount legs, one on each corner or the rear The engine mounts on the TIO-540's take the large Lord mounts we use, and are often thrown out by Another P/N for the large dia mounts is 76790. Preferred airparts had 30 new and 4 used. Prices were $150 Engine Mount Modification Hey Scott: All kits after #80 (I think that was the cut-off) will get the Mk.2 mounts (already modified). Bill No. As I wrote earlier, I think the cut-off was #80, and all after that one will be the Mk.2 units. Mark Has anyone considered the potential of distortion ( its called thermal .063 4130 for the gussets. I feel from my experience in fabrication that securing the EM to a 1/4" or Hi Fellas: If you want to modify your EM before reaming, go to the manual update page & see how it was done Hey Guys, I just talked to Mark about using a Dremel tool to clean things up inside the sockets and he agreed I have been getting some good flight time in on the F-1 in the last few In case your credit is bad with the Snap-on guy, or you're lazy and want to order online... like me... The factory used 4130 steel .125 for the gusset that it is presently installed on your engine mount. For the I finished reaming the gear leg sockets which was not much of a job because I was able to bolt the mount Mark, I feel like I’m missing something important here. I remember the problem you reported on
Howard . Doug has over 150 hrs on his and he put his together dry and has had no problems The real problem is the socket; the mounts breaking in other areas are a consequence. A morse taper is To Mark and other builders...I haven't got the reamer yet, but hope to have Just spent the last 8 hours fussing, bending, pulling, pushing, swearing, banging Engine Mount Welding Listers Dave I had my engine mount reamed and bolted to the fuselage when it was removed for welding. I made a Engine Mount/ Mk2 vs.Indy Mk1 Mark - is the engine mount shown on Randy Pflanzer's web site the same as > > the "new style" ones you Hey Guys, Although we think the Indy mounts are an improvement over even the Mk2 mounts (different mat'l Hey guys, First, let's look at the failures: The first mount ot fail was due to an out-of-balance condition. We replaced Mark, I have a question about any of the mounts, new or old. The holes in the firewall weldments are drilled to Billy, I'll answer this for Mark since we did check and see the difference between mine and Jim's fuselages. Hi gents Indy Mount Has anyone mounted a new style Indy engine mount to their plane. I'm finding that I will new almost a 1/4 inch Yep!!! I put 2 Lycoming engine mount washers in there,one each under the mount.Usually an engine mech will I only needed a measely .032 washer on one of the inner mount pads. Must be SHOP TIP: Shimming at those two points is standard. We had to build in some areas of adjustment, and that is Has anyone installed a indy mount out there? Is the install proceedure the same Scott, the mount holes are .010 oversize intentionally to give some wiggle room for guys who already drilled
Hydraulic Reservior I asked Bart Leblond where to mount the H.R. and he said to put it 4" off center to avoid the oil filter.
Gear Leg Fairing Mark and others, I'm finishing up the gear leg fairing (GLF) and lower gear intersection fairing (LGIF) installation. Do you see a problem if I attach the GLF to the LGIF with a screw and nutplate? Since I had to split the LGIF (couldn't get it off and on) and I had to make it removable (can't reach the upper pant attach screws), I need to install small screws to hold the two halves together. I'd like to mount one of the screws to go through the GLF. That way, I don't have to worry about the fairing sliding up and down the gear leg. I figure just one screw will still allow all of the parts to flex and bend without breaking anything. With the LGIF split, I can remove it to pull the hinge pin in the GLF so that it can all come apart in just minutes. Also, when I installed the stiffeners, I ran a length of 3/8" aluminum tube down the backside of the gear leg. I ran my brake line (1/4" aluminum tube) inside the other tube, allowing it to flex and float free. I did this on my RV-6 and it worked great. Randy #95 http://mywebpages.comcast.net/f1rocket/ I suspect you'll be OK that way. It may require a larger hole thru the GLF -- maybe 1/4" -- to allow for some relative movement during ground ops. I would expect some problems if this was done at the top, unless the hole was maybe 3/8-1/2" dia (lots of movement there!). Carry on! Mark Mark, F1'ers: GLF........In the manual it recommends lifting the airplane to establish the flight attitude for GLFs and the fitting process. I noticed on Vince's site he weighted the airplane with 1200# of sand to simulate a max loaded ground condition. Vince you mention John, Mark and Tom Martin have seconded this idea. I can see the loaded deflection of the legs plainly and understand the value of the process. So which condition is the way to set up the GLF's 1. Unloaded as the manual states for flight or 2. Loaded as it seems the corporate knowledge indicates for ground max deflection. Help experienced ones! Who is correct here? Best Howard Howard, you only care about the glf alignment in flight with no weight on the wheels...Regards, Bob Howard It is best to install the gear leg farings with the aircraft unloaded. The upper gear leg farings should be installed with the aircraft loaded. Tom Martin Mark If you fit these farings without load,what you will see, on the ramp, is that the inner lower surface of the upper gear faring will pull away from the GLF and leave a gap. This may not be noticeable until after some hours of flight. It is not really that big a deal, check out planes on the ramp and see how their upper farings fit. Tom martin I am clear now on variables involved thank you for the reply. I will alter UGIF as required and notch the GLFs top and bottom. Best Howard Last night I popped the fiberglass fairings (that were molded in place) off of my airframe, gave them a quick clean up and rough trim. Next I put them back into position and drilled a few clecoes where the screws are gonna go. So far, so good. Then I unloaded all of the sand (1200# of fun, fun, fun) and tossed it into the back of my Avalanche. It's going back to Home Depot. Weren't they nice to let me borrow it? (Howard, I unloaded the sand... my wife was no help. Neither were my lazy slugs teenage sons. And the cats just tried to trip me.) The GLFs, UGIF, LGIF, gear legs, and stiffeners are so happy together that they can hardly stand it. No cracking, no popping, no unsightly gaps. Either with or without a load on them. As it turns out, I did understand what Tom and others told me to do. There are new pictures of the results on my site... but aren't you supposed to be working? ;-) Have fun, and remember these opinions are expressed by someone with serious dain bramage. (By definition, all airplane builders have this affliction... just ask their wives.) Vince (BTW, making the UGIF and LGIF from scratch isn't what I consider fun. I recommend trying Mark's parts first. My Cleveland brakes and Sam James wheel pants really SNAFUed my installation)
Gear Legs Just found my right gear leg upper nut completely loose and hanging on the safety wire again. Total time is now 38 hours, and I last checked the legs at 20 hours, and they were tight at that time. History on this subject is tight on initial installation, found both nuts loose after a couple taxi tests, tightened up and safety wired again, started flying, and have been inspecting it every time the cowl is off ever since. There was no additional looseness since the taxi tests, until now. Only the right side found loose this time. By the way, a pair of channel lock pliers is what I use to get in there and tighten the nuts, as it is very tight with the engine on and all the stuff in the way. For those of us flying, or taxiing, Keep checking those nuts every time your in there. Greg Nelson Greg are the nuts backing off or are the sockets just wallowing out or stretching as the gear "wiggles" The question that Bill asks is a good one. Are the nuts getting loose as the gear "nests" farther in the socket or is it just that we need a better method of securing the nuts. There is no locking feature with this nut, perhaps we need a lock washer or even some locktight in this location. Tom Martin I had a very hard time tightening the gear leg nuts. I could not get them tight enough with some smooth jawed channel locks so I visited the local tool store and bought the proper size wrench for about $13.00. Thats a lot to spend for two nuts but I beginning to think it was a good investment. Jack #70 Just a thought here- what does the manual tell you to torque them to? I think it was about 45 lb/ft- it's a pretty big nut, so I would imagine that it would be difficult to torque it with pliers. I deal with fasteners in high-load areas all the time, and loosening is usually cased ether by incorrect torque, material defect, or a design flaw- no rocks being thrown here, just pointing out my experience (I'm a Field Service Engineer with GE Aircraft Engines and deal with this all the time). One way to tell how much torque you can get on it is to tighten it the way you usually do, match-mark the nut and leg, and then torque it to 50 lb/in (I'd go on the high side of the range if it is loosening) with a torque wrench. This will tell you if you had been getting enough torque on it initially. If not, that was the problem. If you were getting enough torque, that is another story... Jack- too high a run-on torque can indicate problems also. When I encounter this, I use a dial torque wrench to measure the run-on torque and if it is over the spec value (Mark F. can provide) there is either a problem with the nut or leg. It may have been designed with a high-run-on torque. If there is no locking feature, this is probably not the case. I agree with Tom Martin that we may need additional locking devices or a new style nut with some locking feature (hopefully this is not a nut we will routinely have to remove). Wes Triff # 14 I believe the gear is moving up in the socket, the nut is same place, rotation wise, as the safety wire gives it no choice. It is definitely the gear moving up in the socket, the nut is not rotating and getting loose. Greg The run on torque is virtually zero, you could spin it on with your pinkies. I originally torque the gear nuts to spec as called out in the manual. One problem I see with this hole deal is how close the nuts are to the firewall. Because they are so tight to the firewall, the nut must stop with a flat against the firewall, or I fear it would rub a hole in the soft stainless if one of the six points is pressing into it. This limits your torque job anyway. They are not coming loose due to vibration they are loosening due to the leg settling or seating into the socket during operation. I actually fear too much torque could lead to other problems by loading the socket around the circumference. However I also believe that a loose gear leg will slam around in there also spiking up the stresses. So snug is the answer. Greg
I agree with Tom- the fact that the nut did not move throws out the torque issue and sheds new light on this. All fasteners I deal with are seated on parent material, and the inside finish of the mount sounds a bit iffy, so I'd clean off the mating surfaces (inside the Morse taper and on the mount-nut surface) and let the gear settle in (as Luis suggested). Keep us posted on the results! Wes Triff #14 Greg I'm having problems with this thread. Are you torqueing the nut to the reccommended torque setting and by what method? Bob Wahl My intention now is to use some sheet metal body spoons to make some "as discrete as possible" indentations aft of the gear leg nuts. Two reasons, 1-get a socket on the nut when motor is mounted, 2-points or flats aimed at firewall will be not a factor as Greg has wisely pointed out without the "dish". I ran into the problem when running down nuts of even getting a socket on the nut so tight was the firewall clearance. My big question to folks flying, when the cowl is pulled is there sufficient space to get a LOONNGG torque wrench angled off to the side in there? Are too many accessories in the way? Jimmy what are your experiences after a few more hours on the airframe? It seems the problem is narrowing down to the taper in gear leg mount sockets and the break-in involved. Tom is smarter than I in his honing and clean up approach. The Petr and Wess, as practicing Engineers, can nail this down we hope to perhaps a QC issue on the gear leg sockets???? Tighter manufacturing tolerances??? Something else??? Good week to all Howard When I mounted the legs on the engine mount I noticed I could check the nuts once a week and I could turn it about 1/8" every time. It finally got to a point when it stop turning. Then I had the need to remove one of the legs. Guess what? It is a mother to remove. It appears, once it is there, it really wants to stay there. I hope I don't ever have to take those out. Ok, the gear is drawing up into the socket. This socket is a standard Morse taper, the same kind that machine shops use to hold tools in place on lathes, I find it hard to believe that the leg is drawing up into the socket unless, like in my case, the socket was not perfect to begin with. When I was fitting my gear legs I was not happy with the amount of thread that was showing above the nut. Removing the leg I found that the surface of the tapered socket was not all that smooth. I purchased a little hone from my auto store, these are the ones that are used to hone the inside of brake cylinders on cars, and I honed the sockets. This did smooth the socket to a more satisfactory level and the gear leg did draw up farther into the socket. I was able to gain one thread on one leg and almost two threads on the other. I did not remove anything from the socket other than some high spots and tooling marks. I have two engine mounts here and they are both the same way. I have no way of measuring the surface of the socket to determine if it is true at this point, but it is much better. There are some other possible reasons that could explain the gear sliding further into the socket. The socket could be expanding and or the gear leg could be wearing. This seems very unlikely with so few hours. If you did not remove the powder coat from under the nut it might seem like the gear leg was coming up when it was only the powder coat compressing. I measured the depth of the powder coat at .015 thou. This should be removed from any spot on the engine mount where there is a fastener attached. I am not a big fan of powder coating as it is very difficult to see what is happening to metal under the product, cracks do not always show through. It would be nice if we could get the Czech engineers to respond to this issue as it really is something that is out of my area of experience. Perhaps Wess Triff could comment on my speculations. This puzzle will be solved. Tom Martin My intention now is to use some sheet metal body spoons to make some "as discrete as possible" indentations aft of the gear leg nuts. Two reasons, 1-get a socket on the nut when motor is mounted, 2-points or flats aimed at firewall will be not a factor as Greg has wisely pointed out without the "dish".I ran into the problem when running down nuts of even getting a socket on the nut so tight was the firewall clearance. My big question to folks flying, when the cowl is pulled is there sufficient space to get a LOONNGG torque wrench angled off to the side in there? Are too many accessories in the way? Jimmy what are your experiences after a few more hours on the airframe? When I mounted the legs on the engine mount I noticed I could check the nuts once a week and I could turn it about 1/8" every time. It finally got to a point when it stop turning. Then I had the need to remove one of the legs. Guess what? It is a mother to remove. It appears, once it is there, it really wants to stay there. I hope I don't ever have to take those out. At the beginning stages of fitting the gear legs I also removed the powder coating that I believed was on the way. I also found some welding residue on the inside of the socket that needed to be smooth out. These were not allowing the gear leg to go all the way in. I could put the nut but I knew it needed a bit more thread as Tom mentioned here. Once those rough spots were taking care, I could get more thread to show up. It now appears to be all the way in. We'll find out after a few taxi. Luis 21 Anybody ever give thought to chilling the gear leg before installing? I mean really chilling, like liquid nitrogen chilled. Then stick that sucker in and tighten that nut up. After reading all the posts on this subject, the looseness is starting to make sense. I did nothing to the EM taper other than remove a little powder coat over spray in there, and remove it from the seat of the upper nut. Sounds like the surface finish, and possible imperfections were keeping the leg from seating all the way into the cone, but over time these things wear in, so I'll just keep checking that nut every time I can see it. Eventually things should stop moving unless something else is going on, but I doubt anything too dramatic is happening down there. It was torqued to spec only once, because after installation of the engine I can't even begin to get a socket on that nut. Possibly a big crows foot but I have not found one yet. Besides with the firewall in the way, you can only do so much. I am using stiff, .041 safety wire, to insure the nut is not moving in service. Little dishes in the firewall in the area of the nuts is a great idea for those ships still under construction. Its probably not worth the effort for the completed birds. Greg Nelson I second Tom's opinion...I'd really like to hear what the status is behind the engineering efforts by Petr and co. I will be quite honest here and say that I'm a little frustrated that this problem hasn't been solved yet, as I am ready to mount my engine, and have been patiently waiting for a course of action. I know some other builders feel the same way. Fortunately, I still have plenty of other tasks to work on. I do have a couple of things I'd like to say in this regard: 1. I hope the tapered sockets are not being welded after they have been machined. This would certainly cause the problems that some of us are seeing with the gear legs settling. Any type of welding would cause the taper to shrink after it has been machined. 2. The surface finish of the ID is too rough for a reamed Morse taper. My opinion is these should be reamed as the last step after powdercoating and sprayed with a rust inhibitor such as LPS-3 before shipment. The finish should be as smooth as a baby's butt. 3. The tubes that the bolts pass thru to the firewall should be of greater thickness. 4. The forward-facing tube that is welded to the top of the gear socket should be gusseted. I've been debating about incorporating these changes myself, if nothing happens soon (my TIG welder in the corner of my shop is just begging me), but that would not solve our problems collectively. As a side note, I've had cracks in my engine mount on my RV-6 and Van's acted like they never heard of that happening, even tho there are several RV's in the Indy area where I live that have encountered the same problems. It was ironic that they have since beefed up the mounts on the RV-7 (this was only a few months ago.) So gear problems aren't limited to the F1's or Harmon's. It may be a fact of life with the Wittman-type engine/gear mounts but I'd gladly pay the price in weight penalty if the mounts were made to be much stiffer. I've never heard of an engine mount being too stiff causing problems. The last thing I'd ever want to see is a gearleg fold underneath an airplane, especially ours. Bob Regarding all the discussion about gear leg looseness. I am sure the gear leg is seating deeper in the socket causing the nuts to be loose. If there is weld residue in the socket, which I believe mine has also, it means they did not ream the bore after welding and this is a BIG NO NO. The residue is oxidation caused by red heat on the outside of the socket during welding. You just DO NOT weld on a machined part without refinishing (reaming) afterwards. The socket will also not be round any more as the weld draws, pulling the bore out of round. If you can get the gear leg out, it will probably show signs of galling from the high spots in the socket.Jim Winings #34 Where can Mark F. get a reamer big enuf, so he can pass it around to the builders to fix his problem? They're about $200 from mscdirect.com, but we need to know the morse taper # first. Here, here! I agree with Bob. My TIG has been saying the same things to me. I'll save weight somewhere else. Is Petr also investigating potential cracking problems or just the gear leg socket thing? I'm anxious to hear what Petr and Co. have to say. My mount is ready to be permanently bolted in place. I really don't want to do that until the mods, if any, are complete! I've got a brake hone like Tom Martin mentioned. Is that the best way to get rid of humps and bumps? Anybody got a Morse taper reamer to share? Nobody said anything about chilling the gear leg. Liquid nitrogen and dry ice are readily available at welding supply houses. LN2 is around -196C and dry ice in acetone about -77C. I'm willing to bet that after reaming the socket so it's smooth and chilling the gear leg, you'd never have a loose nut again. But how cold is cold enough? Morse taper in Mills can be quite firmly attached with placement in household freezer, so I think that liquid nitrogen is overkill. Hi Fellas: > > Well, we have the results of the analyzing of the Engine mount and gear leg > assembly. This testing showed some surprising results, to say the least. I > will make the appropriate changes to the manual. > In the meantime, please note the results and clean all debris and grease > from the lower socket area as noted. We will come up with the proper > reaming tool as quickly as practical, and distribute this tool (or tools) > among the flying ships first, and then to the ships which are closest to > flying, and then to the remainder of you builders. > > Cheers! > Mark Hello Mark, >> HPAI ordered in Aeronautical Research and Test Institute an analyze >> of possible reasons for cracks creation in F1 engine mount. Here are >> results of this analyze and some possible solution recommendations: >> >> 1) The main reason for cracks creation in upper area of main leg holder >> in F1 EM is a shimmy effect of leg during taxing. The cracks have two >> cross direction which show us that the leg is loaded by torque and this >> torque was supported only in upper area of EM by slot and nut. >> >> HPAI note: All notes about nut loosing and problems with their fixing >> support this idea. > > TR LP note: We will suggest balancing of all wheel/tire assemblies > prior to taxi testing any of > >> the F1 series ships. >> >> 2) The problem of upper fixing is coming from not perfect geometry >> of Morse cone at the lower end of the leg socket by welding operations, >> tolerances, coating, etc. >> By this way there is no fixing of torque in bottom EM area with cone >> and torque is transmitted to the upper area of the socket (flat sided hole >> at the threads/nut). >> >> HPAI note: Mr. Winnings notes are correct, we need to ream the cone >> once more after welding for proper function of the Morse 5 cone >> connection between leg and EM. >> >> 3) All these torque problems are even bigger by notes in assy manual >> about use of some oil or grease in cone area for the reduction of all >> friction >> and by this application, the cone's ability to absorb the leg torque is >> defeated. >> >> HPAI note: Please don't apply grease in cone area and keep it dry as >> possible. >> >> 4) All technology or design changes can only elongate time for >> cracks creation if we don't cure the shimmy problem. >> >> HPAI note: We know that similar structures are working longer >> by application of one cross bolt in bottom area. This bolt is loaded >> by torque from shimmy shaking especially as we know now. We >> suggest that HPAI and Mark will issue exact positioning of bolt and >> some notes how this operation can be easy and correctly done >> by any builder. We must specify which dia. bolt, and the location of the >> bolt hole, with Mark. >> >> 5) The assy manual description of leg and wheel positioning/alignment is >> not >> complete enough by Institute point of view and it does not protect whole >> assy >> from the possibility of the shimmy problem. >> >> HPAI note: Here we expect some range of tests from Team Rocket >> for a smallest amount of shimmy by a specified wheel position. >> We cannot make these tests at our factory because no airplane is here and >> the >> testing processes in Institute laboratories are very expensive. >> >> 6) Some cracks were created later by this primary problem and >> these have no direct relation to problem. >> >> HPAI note: We can make some small minor changes in new EM >> production by better fixing and dia increase of bolt tubes for connection >> to firewall. >> >> >> Short review: >> >> A) ream the Morse cone to correct shape after welding >> B) clean all grease or oil out of the cone area >> C) fix leg and tighten the nut to the correct torque (no coating or dust >> in all areas) >> D) drill cross bolt hole in bottom cone area by sketch and install bolt >> E) install axle holder and wheel as correct as possible by F1 manual >> >> TAXI and FLY >> >> >> Have a nice day >> >> >> Petr (doctor Watson) >> >> >> P.S.: The real Sherlocks are in the Institute! >> Hey Mark, The RV's have a small piece of tube welded on the bottom of the gear socket horizontally tying into the bottom cross tube. I never understood why that was there until now...to keep the EM sockets from twisting with torsional forces. Learn something new all the time. The bolt in the lower taper area is a good start, and certainly explains why the upper socket pieces have cracked. However, I still think things should be beefed up a bit more, because there's no 100% cure to keep these gearlegs from shimmying. I would also have to guess that the new bolt should be drilled after the gearlegs have settled into the taper (after reaming, of course). Maybe some taxiing or a flight or two then drill for the new bolt. Bob Well, we think the corrective action on the cone will allow a good fit from the start, so the bolt can be drilled at first. I suspect micro-rotations of the leg (due to a bad fit and grease at the cone) are loosening the nuts. Shimmying: each ship will have a different shimmy speed. Simply go thru it quickly, and don't taxi at that speed. Ever. I doubt there is any reliable way to eliminate the shakin' shimmy dance, but we can minimize it. Mark I wonder if a sleeve over the socket for the MLG would do it? Must be too simple or an engineer would have thought of it. Bob Hi guys, I've been in Texas for about three weeks, and just finished the 150, or so, emails that have built up. I will give my gear another quick check before flying again, but the last time I looked at 70 flying hours, the nuts appeared to still be tight. We did clean that area thoroughly during assembly, and maybe that helped. I do still have a little shake just above normal taxi speed (on landing rollout), and nothing I do seems to stop that. Its probably a normal characteristic of this type gear. I may have access to a morse5 taper reamer here at our local welding/machine > shop. Is it suitable, or are there unique features to your reamer? Eric #45 That is the correct part, as far as I can tell. Don't remove too much metal please! And, no grease upon final install. IF we decide to have the builders install a torque botl in the lower socket area, it will likely be done with the engine mounteed etc. Stay tuned on this one. Cheers! Mark Some notes. Today I remaned my engine mount. Bob Haynor...I will send you the reamer on Monday. Don't go to the gym the day you ream. You will need you strength. I reached the 11/16" limit before getting 85% contact area. Your mileage may vary. The reamer works well and is pretty easy. Have a 1" open end wrench handy to turn the reamer. I redrilled my left gear leg today to fix it. I made 18" sq grease plates to allow the airplane to sit on. This made it pretty easy to see/measure what was going on. All said and done, with the ship in level att, I have no toe in. With it in 3 point attitude, the toe in sits at 5/16" difference at the ends of the 13.5" jig tool noted in the manual. I have yet to calculate this into degrees but it looks like maybe 1-1.5 deg. Hope this helps the rest of you for reference. BTW, the aiplane rolls easily now and the tires don't squeal any more. Had I to do it again, I (IHMO) would do both gear legs this way rather than the jig method in the assy manual (which I screwed up). Regards, Bob Gross Guys, For those of you that have all ready done this I am looking for some wisdom. I have the reamer in hand and am ready to try this but I don't want to #$%@#% it up. So, any words of advise would be helpful. Mark mentioned once about stopping with 85% contact. What exactly does that mean? Do I have to worry about keeping it straight, if so how? For those of you that have all ready done this I am looking for some > wisdom. I have the reamer in hand and am ready to try this but I don't want > to #$%@#% it up. So, any words of advise would be helpful. Mark mentioned > once about stopping with 85% contact. What exactly does that mean? Do I > have to worry about keeping it straight, if so how? > Hey Jon: Use plenty of cutting oil. Stop reaming when the protruding threads measure 11/16" or less. Don't try to get 100% contact -- it ain't gonna happen (there isn't enough material there). Don't worry about keeping it straight -- it will naturally got straight by itself. Use plenty of cutting oil! When finished, clean the socket & leg before installing. Tighten the nut to 40 lbs/ft and safety. Cheers Mark Are you using a hinge on your gear leg fairings? Bob W Nope -- just glued 'em together. Some folks have not had good luck with this type of attachment, but we can't tell exactly (except for the one fella who used polyester). We added a small pc of cloth at the top & bottom corners, over the resin/milled fiber slurry. On my other plane, any separation always started at the top, and this cloth re-inforcement might help reduce that problem. If you start to notice some separation, I used Goop brand marine Adhesive to make the repair. That is some really sticky stuff -- a friend actually used it to close his leg covers, and it has worked for about 3 years on his RV6. Cheers Mark I'm not Mark, but I used a hinge, I'll bet he didn't. I was able to put the pin in without drilling a hole in the fusalage. the only mastake I made was getting the trailing edge togeather too tight so that the UGLIF witch I had already fitted had a little extra gap. So if you use the hinge do it first before you do the GLIF's. Jack #70 I have my engine mount bolted to my work table and I'm in the process of attaching the legs and the axle attach brackets. While I'm doing this, it seems to me that it would be a whole lot easier to go ahead and attach the brakes/wheels/tires at this time so that I can fit up and attach the wheel pants. Since the wheel pants should be attached parallel to the direction of flight while airborne, that would be easier to accomplish over on my bench rather than trying to jack up the airplane and drop lines all over my garage floor. Am I missing something obvious here? Randy #95 Hey Randy: It MIGHT work...but the pant is NOT aligned with the ships waterline when viewed from the side -- the tail is a little high for gorund clearance. The axle centerline measures 6" from the ground (tire is compressed, you know), so use this measurement to figure the upward offset of the tail. While you're at it, go ahead and install the leg dampers -- alignment is important here too. It's OK if you run the brake lines down the front of the leg at a later time -- I woudn't install 'em with the dampers in this case. Cheers! Mark I intend to install my wheel pants higher on the tire than what is shown in the plans to accomodate 1) grass/rough strips, and 2) a potential flat tire. I had my wheel pants on my RV-6 mounted too low and they took a pounding. I'm not sure how I'm going to be able to figure out the angle. Does anyone have a measurement of how high the tail of the wheel pant is off of the ground with the fuselage level? Randy #95 The setup in the manual is OK with grass -- it's what I operate from here! I've run over those blue reflectors on the taxiway too -- no damage. I'm not sure you want 'em high enough to take a flat tire... > > I'm not sure how I'm going to be able to figure out the angle. > P357 of V2.25 says 7 1/2" with 35PSI in the tires... Cheers Mark That's exactly how I did my axle sockets, wheels and pants. Much easier than jacking the plane up in the air! I did my RV-4 this way also and it would go 200 on a tired old O-320, 150 hp. So this technique must work OK! pics and procedures on my website. Scroll about 3/4 down the page. http://www.usi.edu/science/chemistry/vfrazier/landing%20gear%20and%20related%20s tuff.htm Vince Frazier Gear Leg Solutions what is the latest fix for the gear attach problem? Are we passing around the special tool to ream this upper socket? Can this be done hopefully after the engine is mounted? Yep -- a special reamer with a pilot shaft to line bore everything back to spec. The CZ boys are producing 4 tools (1 will go to Australia for Doug Watson's ship) and these will be passed around from builder to builder. I don't expect the reaming operation to take more than 10 minutes or so -- and can be done on the ship. Refitting the legs might be a problem -- tightening those nuts with the engine in the way is not so easy. Luckily, the engine can be taken off in 10 minutes or so, and moved slightly out of the way for easier access to those big nuts. How much TORE QUUUUUUUUU on the bolts Boss man----2lbs of muscle and 40lbs of ass do it?????? Hey Bill: I hope you refer to the leg nuts!! 50 lbs should do it -- keep an eye on 'em as the ship builds hours too... Cheers Mark As I was reaming the sockets and getting close there was about 3/8" of the cutting surface of the reamer still outside of the socket. When I tightened the gear legs I had 2 1/2 threads showing above the nut. I did not try the legs while reaming. I was looking for a clean cut mark totally around the base of the gear socket. The high spots (where the welds were) came off pretty quickly but I wanted a good fit all the way around the socket at some spot. On mine it was the bottom edge. Jack #70 Mark, in a prior msg. discussing the reamer operation, you said: check the >> fit of the leg into the socket as you proceed, and stop when you have 11/16" >> of thread protruding from top on the socket. QUESTION..Is this measurement >> made after torqueing the gear leg nut ?? or a free fit?? billy waters > > > Free fit. It's not going to move any measurable amount with torquing. > > Remember to install dry! > > Cheers > Mark Doug Watson only put a very very very small amount of oil (just a smear) on his when he assembled and has no seating, cracking or loosening and he has 140 hrs up so far Kaos When reaming my gear leg sockets, I never got 100% contact around the bottom end of the socket, rather the top end got it. After installing the gear legs, It took one flat of the nut to go from finger tight to 50 foot lbs. I have 2.5 threads showing on one leg and 3 threads showing on the other. I made a crows foot wrench that easily tightened the nuts with a torque wrench. Total contact area was extimated to be approx 65% by the time 11/16" figure was reached. About finished up those miserable baffles now. New pics on the web site for those interested. Regards, Bob Gross That makes perfect sense to me. Typically when something is welded it usually shrinks a slight amount. That's why the bottom is wider, since it is the area farthest away from the welds. Bob #80 Hi Fellas: Dearest Mark, Been reaming today. Not much more fun than being reamed. Very little material is being removed before the limits of 11/16 are being reached. There are still assymetrical marks (no relation to Mark F.) appearing on the gear leg. That tells me that there are still high spots inside around the weld clusters and I don't know if what we are doing is really having any real good. In fact with just a light honing with a scoth brite wheel on a die grinder is getting us to the limits on the first two mounts before reaming is even attempted.with . My question is... can we have these flats machined longer and have a new radius machined giving us about 1/8" or more travel before the limit is reached? I just don't like the fact that there is now no more room to tighten the big nut if there is some slight settling in service. There appears to be enough thread left to allow for some machining. Reamer and reamee Terry and Wayne Gear Leg Torque Hi guys, I think this one is worth filing away for future reference. While at OSH I talked to Snap-on tools and ordered a special crow's foot for the gearleg nuts (3/8'' drive and 1 5/8'' opening). Eric Hanson had mentioned this to me some time ago, and it works. Everytime I check the nuts they are loose, even with tight safety wire. With the engine on and plumbed its a bear to get to them with a socket. However, with the crow's foot its a piece of cake, and I can use it with my torque wrench. Cost was about $30. Also, today I finished installing the TruTrak digital wing leveler. It installs quite easily using the RV-4 servo mounting bracket which is included with the unit. The head fits in a standard 2 1/4'' hole. Once I finish the wiring harness and get a test flight, I will give you a report. It looks real good so far. Jim Cash Jim It would be interesting to know if the leg is pulling up into the gear socket with time, or is the nut just coming loose. Any chance of getting an accurate measurement of the threads extending from the socket and checking it the next time the nut gets loose? If it is just a question of the nut coming loose than I would consider using some locktight after a settling in period. There is a reamer making the rounds for those of us in the building stage and hopefully it will let the gear legs "seat" so that the nut does not come loose. Tom Martin Hey Guys, why not just index mark the gearleg nutz to see if it moves ..billy Hi Billy, I did in fact mark the nut the last time I tightened it. The nut is not backing off. It is a very course thread, so a little turn goes a long way. This time I did get a torque wrench on it with the crow's foot, so it will be interesting to see if it continues to seat. I have not used the reamer, nor do I intend to. Eventually it has to seat. Jim I did the ream job last week and after doing it I highly recomend that it must be done. Only about 10% of my left gear leg socket was making contact with the gear leg. The right one was not much better. After reaming the gear legs pulled up very smooth and snug. Jack #70 Mark, in a prior msg. discussing the reamer operation, you said: check the Free fit. It's not going to move any measurable amount with torquing. Remember to install dry! Cheers Mark Mark, > Speaking of gear mounts, why do we assemble the gear legs dry--just makes > my skin crawl thinking Mark, this is a question that Jim and I 'agree to disagree' on. My experience with 4130 and 3AL-2.5V titanum is Will do. Thanks. How 'bout some more torque on those big nuts to keep things snug, or is 40 ft-lb all they are I certainly disagree with Bob on this one. The last thing you want in a Mark, In v2.26 p348, the manual shows a torque of 50 ft-lbs for the nuts, but p487 sez We put a 2' bar on an old Model T Ford wrench and pulled pretty stinkin' hard. We probably got about 70 lbs/ft on 'em, and they have not loosened. This is on a Mk.2 Mod.1 mount.... I'm worried about pulling the threads out on either the leg or the nut -- either would be pretty bad -- thus the lower limit. For socket retention, 500 would likely be about right. I see a non-answer above -- use the 50 lbs/ft setting if you have a proper torque wrench. Might need occasional re-torquing. Cheers Mark Gear Leg Fairings Since I'd rather be thinking about F1's than work right now, I have an idea that I would like to pass along. I have Mark's gearleg fairings on my -6 and since I'm based on not-the-smoothest-grass-runway-in-the-world, I have a crack in the middle of both fairings. Tom Martin can attest that a crack in the gearleg fairings is one of the first things people notice. My gearleg fairings are bonded at the trailing edge, and on the F1 I plan on something a little different. I am going to use hinges to join the trailing edges, but am going to cut every other hinge eye out so that the aft portion of the fairing can slide along the hinge pin so the fairing can flex somewhat. Mark, could you maybe experiment with that? With the hinges in there it would make it a lot easier to remove the fairings for repair. Bob #80 I am going to use hinges to join the trailing edges, but am going to cut > every other hinge eye out so that the aft portion of the fairing can slide > along the hinge pin so the fairing can flex somewhat. Mark, could you > maybe experiment with that? Hey Bob: Other than producing some urethane foam fairings that would bend with the leg, I can't figure out how to eliminate this cracking. The cracking DOES indicate a hard landing, which should tell you to inspect other parts of the ship too...so it ain't all bad... The fairing breaks when it is bent too much along its 'spar' axis. I don't think allowing the TE to slip like you plan will help any. A thicker foil would help, but that's more drag... More ideas? Mark The local Harmond Rocket that I have been looking at has Alum. gear fairings made from two pieces overlapped at the middle of the span so I asume if not connected would slip somewhat. Jack #70 Bob, I have 75 hours on my airplane with the trailing edge hinged just as you suggest, except I did not remove every other eye. No problems so far, and if in the future they need to be removed---piece of cake. Jim Cash Hey guys, I went out yesterday with the express intent to once and for all test my gear leg fairings. Decelerating from Mach-2 (no I won't tell you exactly how fast---suffice to say fast enough), the only thing I felt was a bit of mach tuck in the transonic region (normal), and low and behold the fairings are still there. Suggest that installing the hinges might be a good idea. I just installed a set on a new F-1 (which we will fly in a couple of weeks) and they are stronger with the hinges without doubt. And, a quick sideline---If you saw the ad, disregard---When my hand was placed against the hot skillet I couldn't do it. Blackjack is still THE MAN! Jim Cash Jim, Are these just regular gear leg fairings, except with a hinge running down the trailing edge? And some foam at the top and bottom? You can tell me how fast--I'll keep it classified--promise. Bob Hayner Gear Leg Fairing Flutter As Mark has mentioned...make sure your glf are bonded exceptionally well, or this will happen! Du-oh! Duct tape to the rescue, back airborne though. 11.9 hrs to date.This happened this am, around 225mph indicated and about 3g. Eric Any reason not to make the gear leg fairings out of aluminium? Would not appear to be a difficult fabrication job. My Cardinal hasn't had a crack in its aluminium fairings for >25years (granted it only manages 130knts.) F1 builders I have used a riveted on hinge on the back of the faring with good success. This will allow the gear leg faring to be removed for inspections and minor repairs. Tom Martin Let me offer a strong second to Tom's suggestion. The hinges work great, and I have had my F-1 out to 265 MPH indicated with no problems. A little expandable foam on both ends and quickly tightening the upper and lower farings allow for a strong setup after an overnight sit. Jim Cash I have this strong urge to say "WHY" on so many occasions, as I observe on the list. I have used both metal and glass on the farings and both work well. The problems you have seen lately on early flight F-1s have absolutely nothing to do with the product. Bonding the farings is a poor idea. Hinging is a good idea, as is fiberglass farings on a 300 MPH F-1. I have over 18 months of trouble free flying on mine so far, and although I don't jerk an airplane around, I fly it close to the limit most of the time. Mark, you might want to comment on that. Jim Cash One of my definite "do-overs" is to use hinges on the fiberglass gearleg fairings on the Rocket. Mine have cracked in the middle on my -6 and since they are bonded it means that I will have to do some cutting. With the hinges that obviously won't be a problem if those too crack, which simplifies repairing. Bob #80 in retrospect, and for the next set of glf, I plan on trying the set as |