|Matt Throckmorton's ("DocThrock") Team Rocket F1 EVO Kit Plane Construction Pages|
Landing Gear Last Modified: Thursday, 17-Apr-2008 11:56:57 EDT
On This Page: Wheel and Axle Dampers Wheel Pants Wheel Alignment Brakes Gear Leg Fairings Gear Leg Nut Wheel RE-Alignment Bleeding
Gear legs, Wheels, Tires and Brakes
mount is also the landing gear leg mount. Two
nicely machined titanium tapered rod gear legs fit VERY precisely into
long steel cylinders that are part of the moly steel tubing engine
mount. The two legs are held into the mount by two 1 5/8 inch titanium
nuts which are torqued to 50 pounds and safety tied.
Note: the picture below
shows how the gear legs go in
the engine mount, but this method of landing gear/wheel alignment is no
The Gear Leg "Foot"
At the south
end of the gear leg, there is a steel "foot" or socket.
The gear leg is machined down and the "foot" fits over the machined leg
about 5 inches. At the end of the foot is a pad that will accept the
axle for the wheels, brakes and wheel pant.
The legs are
now securely in the mount, and hanging over the
side of my table in mid air. The steel feet are placed on the ends of
the legs with the round pad facing out.
I used a ruler
and marked several lines across the gear leg
and foot. This gave me a way of making sure I kept the leg and foot in
alignment. One foot was extremely tight and did not want to wander, but
the other foot could move fairly freely. This was a potential problem
I made about 6
marks on the gear leg and foot, and the
carefully tapped (malleted) the gear leg out of the mount. I set up my
"CENTER-IT" drilling jig on my little bench top drill press. This
little V shaped aluminum jig made drilling the center of the round
tubing and leg very much simpler. I bought it at Wicks during OSH. $15
and Axle Assembly
I have Grove wheels and brakes with my kit. I dumped the Grove box out and looked for instructions. They ain't for shit. Don't bother.
I got out the wheel halves and removed the retaining clips that hold in the bearings. I tool out the bearings and greased them but good. I cleaned up the excess grease and put the bearing back in and secured the retaining clip.
I couldn't figure how to put the tube in the wheel. Mind you, I have always done my own tires, wheels, brakes and bearings on my other planes, but I hadn't seen a tube and stem like this before. I emailed Mark and told him I must have the wrong tubes. DOOOH!
After taking a break, I came back and looked at the tubes. They have a threaded stem with a ring and two nuts. No instructions. I finally decided to tighten the two nuts to lock the ring against the root of the stem (against the rubber). This little assembly fits nicely in the round cut out in the wheel halves. I placed the tube inside the 5x500 tire. I then lubed the stem a bit and forced it through the grommet in one wheel half. It sticks out perfectly straight. A very nice assembly!
I then let some air into the tube. It helps to mate the second wheel half if the tube is somewhat inflated. I pressed on the second half and bolted the halves and disc rotor, using 7/16 wrench and sockets to secure them GOOTUNTITE!
Don't forget, you have to align the stem with the red mark (yellow with some MFRs) on the rubber.
I was still waiting for the paint to dry on the gear foot and pant bracket, so I started looking for something "landing gear" to do. I checked to make sure I had the wood dampers that you ProSeal to the gear legs. Sure enough, I still had them. So I unpackaged them and checked them out. There are two halves for each of two legs. I wondered why they came in halves, but oh well, no matter.
I figured I was supposed to glue them together. Nothing in the instructions about this. I had some carpenter's glue I bought about 10 years ago laying around. Sure enough, Elmer was still in the bottle and fluid, not the big rock I expected. So I smeared some to each mating side of each pair. I used different glue patterns on each one, trying to get thorough coverage. Had the Elmer's not worked, Liquid Nails would have been my next choice.
I got out every clamp I own and used 1x2's and clamped all four pieces carefully together. I checked them the next morning and those babies are set! Soon as I get some more parts ready to assemble gear-wise, I'll ProSeal those to the legs, then wrap over them with Fiberglass tape and epoxy.
Rustoleum is not a good paint for my airplane. I figured that out after I painted several different parts with spray cans. Compared to automotive coatings, like PPG Concept, well, the retail rattle-bombs just don't cut the mustard. Everything I've painted is going to get refinished with Concept. Man, I wasted a bunch of time. Now I have lots of stripping, sanding, cleaning and painting to do! DOH!
I sanded and stripped the gear leg "feet" and the wheel pant brackets, then used my touch up HVLP gun to shoot PPG wash primer and primer/sealer on the parts. Next I'll shoot them with PPG Concept. After that, I'll get back on track. I don't want to assemble the brake calipers, axle, and other parts until the bare metal TR parts have been properly painted.
Top coating the parts with the PPG Concept was pretty fun. Once I figured out the right settings on my little HVLP gun, it actually turned out pretty nice. The "warm grey" 1999 Toyota color I picked looks nice and glossy. Except where I shot it too "dry", i.e. not enough paint or too much air pressure. But I got it figured out. Don't think I even had any runs this time. That's a first!
Now that the gear leg "feet" and the wheel pant bracket are painted, as well as the engine mount, I can stick the legs in the mount and assemble the landing gear. That should be a fun little bolt up project. Later on, I'll get the fiberglass parts going. I may not do that until the engine cowl is in place.
Boy, the picture above sure makes my basement "shop" look messy. And it was. I need a lot more room so I can spread out the clutter more! :-)
engine mount to my bench, then stuck the gear
legs in the mount and finger tightened them down. I went ahead and
bolted down the gear leg feet using the hardware supplied by TR.
The order of parts from the foot outward is: foot, pant bracket (long side up), axle, brake thrust bearing. Originally I had the thrust bearing behind the axle not on it. Thank goodness Mark straightened me out on that one. Not shown: there are two bushings that sit nicely inside the bearings on the wheel. One of them acts as a stop on the axle to hold the wheel/bearings away from the break assembly. In other words the wheel is retained in position on the axle by the bushing in the wheel bearing, not by the shape of the axle. The bushings have a chamfer on the ID. On the inner bushing, I put the chamfer inboard against the chamfered step in the axle. I put the chamfer on the outer bushing inboard as well, to give the wheel nut the maximum amount of surface to mate against, plus I thought it might actually stay a little cleaner that way.
Contrary to what the TR plans recommend, I am probably making all of my hydraulic lines out of 1/4 inch Nylaflow tubing. I've had aluminum lines break 3 different times on other planes, so I'm making the switch to nylon. With brass fittings. The burst pressure is at least 1000 pounds, and I've been told that you can't put that much pressure on a brake line with your feet and legs. So I'm going plastic.
Some thoughts on gear legs and fairings. I had the pleasure of flying alongside with Vince Frazier the other day. First of all, I watched him taxi his Rocket on the ramp. His gear legs looked like jelly, even with the dampers. I couldn't believe how much they wobbled, even on asphalt. I asked him about this and he commented that it was fine and just took some getting used to. Dampers have been optional I guess in the past, but seeing how much the gear move WITH dampers, no question I'm putting them on from the get go. Also, Vince flew his first 5 or so hours without his gear fairings or wheel pants on. He said his plane flew straight and true, and didn't need any tweaking. Then he put on his fairings and ended up with a significant turning tendency. I think this comment is very helpful and is going to dictate how I proceed with my wheel pants. I think I will initially fly before I put my fairings on, too. And I'll try not to permanently mount them, or make it so I can more easily adjust their position if the airframe develops a turning tendency after the fairings are mounted. Also, Vince commented that he mounted his wheel pants too low to the ground. Operating off of an unimproved or grass strip requires a little more clearance. Not only will the bottom of the fiberglass show considerable wear, but catching plants and debris will put quite a load on the bracketing and could cause failure of the pants. I'm going to try to mount mine high enough to get off the ground, but low enough to still be aerodynamic. I actually don't know if I can get both. Having decided to proceed in flying first and then adding fairings later, I'm only going to prime the parts, not final paint them. I'm sure I'll bugger them up trying to get them aligned.
I'll be adding the dampers pretty soon. My engine "core" should be here soon (March '05). I will need to reinstall the engine mount and of course the gear legs in order to hang the engine and begin installation of the engine cowl and other components firewall forward (FWF). The plan is to mount the mount and hang the engine in my basement so I can work on the cowl in heated, well lighted comfort. Then I will remove everything back to the firewall, and send the engine back to the builder for completion. At that point, I will move back into the garage and permanently start mounting parts FWF.
After due consideration, I will not be grooving out the wood gear leg dampers for an aluminum sleeve to run inside along the gear leg. There are reports of brake line failures due to running them inside tubing under the dampers. So I am just going to keep it simple and run the nylon brake line along the dampers, probably fastened (more like "guided") with cushion clamps on the top side of the dampers.
The gear leg dampers (as provided in halves) have already been Elmer's glued together (about 6 months ago). I sanded the recessed part that mates to the gear leg in the center with a coarse grit sanding sponge. I cleaned up the glue and the edges. The dampers are 31 inches long and over 3 inches wide at the broadest part which goes near the fuselage. The plans need updated. There is only 32 inches of titanium visible below the fuselage. I would think the more wood you can glue to the titanium, the less wobble you're going to get, so I am reluctant to trim the wood until it measures the 2 3/4 wide measurement in the plans.
What I plan to do is just to slice a bevel on the wood near the fuselage and ProSeal (or GOOP) the wood dampers to the titanium legs.
I think if you leave the corner on there, it's going to interfere in service, plus the damper will extend over the steel foot. The cut might make fiberglassing the tape over the leg a bit easier,too. I think it will work. I checked the fairings over the dampers already and it should all fit together.
I simply duct taped the dampers into place to see where they sit. The plans don't specify where along the leg to put them. Some would think this a no brainer, but I would rather be sure before the ProSeal goes on. Of course you're supposed to use angles and center the damper trailing edges. I'll certainly follow the plans in that respect as soon as I get the dampers cut and confirmation from Mark on the cut.
Mark confirms that I have the right idea, so I'll Carry On! as his emails are signed.
The fuse was already hoisted so I could change the Charley Fox on the wheel assembly order, so decided to go ahead and glue up one of the dampers. Not a big deal. I grabbed some extruded angle scraps I had laying around and quick clamped them to the gear leg flats. I also used a coping saw to cut the angle off at the top. The angle ended up not matching the lower edge of the fuse, but at an even more open angle away from the ship. I have no idea how much flex there is going to be up there, but I don't want the wood contacting the fuse if I have a hard landing. I suppose if it's THAT hard, I'll have other things to worry about besides a couple pieces of fir.
The dampers won't fit between the clamped extruded angles because the dampers are actually wider than the gear leg. Not much, though. I just guesstimated the location of the angles and took the damper to my bench grinder and knocked off a bit of the edges. When you put the dampers between the angles now, chances are that they are going to want to sit at just the right angle. I'd recommend that when you trim the wood in order to fit on the leg in between the clamped angles, you should trim the the edge of the wood where it mates to the leg entire length of the wood so that when you glass it down, you get a nice smooth profile and transition. In other words the wood dampers are slightly wider than the diameter of the gear leg and the dampers need to be sanded or trimmed to match the leg. Remember, you may want to fly the plane without the gear leg fairings on and the dampers exposed to the wind. It's a good idea to have them smooth and uniform.
I used GOOP instead of ProSeal. I have both materials. The GOOP is easier to work with, sets faster, cheaper and readily available.. My basement is cold-ish and my ProSeal is old. When I used it on my windshield, it took about a week to set up. I don't wanna wait that long. I smeared a good coating of GOOP on the gear leg where I thought the damper would contact it. Then I loaded the channel in the leg with lots of GOOP. When I seated the left damper, the thing just went right to place and stayed there. I was thinking I could just leave it that way, but then decided that it might slip over time. So I got out my wooden screw clamps and carefully squeezed them onto the leg and damper trailing edge. The whole thing shifted ever so much with the pressure from twisting the handle of the clamp, so I very carefully scooted the damper back to position by pushing the trailing edge. This is not an exacting process, but you can get it right eyeballing it. The wood just has to be close to centered so it sits under the gear leg fairing (GLF) OK. I went back about an hour after I clamped it and made sure nothing had shifted. I think I'll leave it clamped for a few hours at least.
Two days later, the GOOP is set. I kinda forgot about the gear leg dampers while I was playing with other stuff. I came back to the left leg and removed the clamps. That puppy is one there! I was feeling frisky, so rather than GOOP the other leg, I decided to glass the left leg.
Before I started painting epoxy on the BID cloth, I cut some regular cloth off the bolt. I don't know the weight, it's about the same as my tapes, and FAA certified BID stuff. I had it on hand, so I used it. The plans say wrap a tape this way, then wrap a tape that way. Well, I had some 3 inch tape left and I did a test wrap. Man, it would take a full roll of fiberglass tape to do two wraps on each of both legs. That's a LOT of tape and a bunch of money. I decided to be cheap and use cloth (since I had a bolt laying around), so I cut a tapered piece that would wrap from the trailing edge on the top, then all the way back around, passed the trailing edge again, and ended at the trailing edge on the bottom. That hides the ugly edge, and makes sure the "tail" of the cloth is going aft. Not that it mattered, because I was going to wrap it once with 3 inch tape.
Note: Having completed this process, I probably should have started the cloth in the middle of the bottom side of the damper instead of at the trailing edge, then double wrapped it. That way you would go over the trailing edge twice. The way I wrapped the cloth, the weakest point is the trailing edge because there is only a single layer over it. I'll tell you that it was somewhat difficult to get the cloth to lay over the trailing edge without bulging into big bubbles. A double layer would have been even tougher. The good news is that since you still want to wrap it at an angle, the tape would undoubtedly pull the trailing edge cloth down taught, even with 2 or more layers. But I would imagine that the trailing edge of the damper gets the most force from the shuffle and bowing of the legs. Therefor the trailing edge of the cloth should probably be thicker. As it is I have two layers over the edge, with 3 layers overlapped in some places. Time will tell how it holds up. I think it'll be fine. If not, you'll certainly hear about it.
I slathered the epoxy resin on the damper and over the gear leg. Then I set the bare cloth onto the leg and started wetting it with a 2 inch disposable brush. I did the top, then the bottom, then the top, then the bottom. As I went along, I brushed in the direction of the trailing edge to keep the cloth taught. There was still some air bubbles at the trailing edge. The fiberglass cloth just doesn't want to make that tight of a turn.
I kept brushing and working the cloth until it looked saturated and most all the air bubbles were out from underneath. Then I got the 3 inch tape that I test wrapped on the leg and started wrapping it from the bottom up. I overlapped the edges anywhere from 1/4 to 1/2 inch or so.
Don't forget that all this COULD come loose. I made sure the cloth and the tape were positioned in the machined area of the flat of the leg at the bottom, to help keep the whole thing from slipping down if the damper breaks free from the GOOP bond on the leg. I also lapped the tape over the beveled top of the damper, so the fiberglass would help to retain the damper at the upper end.
I used the brush again to work the tape taught. Be careful not to pull the edges of the wraps apart or you'll have to peel it apart and start over. Don't ask how I know...
Once this was done, I of course snapped a picture then walked away. If the second batch of slow I had to used to put down the tape layer sets in relative comparison to other 4 squirt batches, that tape should be mostly set by late tonight. Sure enough, just before bedtime, the resin was almost cured.
There is nothing holding the tape on except epoxy resin. I did not have to fasten the cloth or tapes to keep them in place when I started. I suppose that if I had a staple gun handy, I might have shot a few staples in it just to keep the tail end in place, but once I wet and overlapped it, the cloth stayed put quite nicely.
Once it completely sets up, I'll check it, perhaps trim it some, then move on to the other leg.
After glassing the left leg, I went back and did the same process on the right leg. GOOPed, left the damper clamped 2 days, painted the surfaces with West System, wrapped 2 plies of BID cloth as one continuous piece, terminating at the trailing edge, then wrapped 3 inch tape from bottom to top with about 1/2 to 3/4 inch overlap. After completing that side, I went back with a course sanding sponge and hit the surface of the other glassed damper to knock down and smooth out the glass. Once both are set up, I'll need to go back with my dremel and clean up the ends. That might have to wait until the legs are off the ship again to do that, which should happen soon. Unless I take down a wall and knock down my fence to get my plane out of my basement.
When I was goofing around waiting to hear from Mark on the Dampers, I started playing with the wheel pants. You have to cut them before you can get them located and install them. They come without any opening for the gear leg. I simply held the front half of the pant on the tire and bracket and marked where the top and bottom of the gear leg would intersect. I cut the "hole" at the mating edge of the pant and tried it on. I had to cut it three times to get it where I wanted it (so far). I shoved the halves of the pants together and marked the "hole" on the rear pant. Then I cut that one too. I did the same thing to the other side and then duct taped the parts together over the tire and rear leg. When you start this process, cut the front half to fit the gear leg and the width of the tire first.
Starting to look pretty cool, eh? Those wheel pants came very clean from the factory as far as the quality of how they mate. The finish in some places kind of sucks, but over all they are VERY nice. Some guys don't like the front/back style pant. Unless I can find a faster set of pants, these are the ones that I'm sticking with.
Contrary to the plans, the first thing you should do when you try to it these pants is BEND THE SHIT out of the wheel pant bracket. I bent the top and the bottom bracket down a lot. Not because they didn't fit the contour of the pant, but because they made the pant too tight. IOW, the brackets pull the pant very hard and bind it against the outside of the tire and the mounting spool. So I bent them and reshaped them a little to take some tension off the fiberglass pant.
One thing I did that was sorta wrong was to cut a bunch out of the rear half of the pants to fit them over the gear leg. You could actually just shave the edge off and get it to fit on the wheel over the axle. I cut completely back thought the "doubled" area that fits under the front pant. It wasn't necessary, but other than cosmetically it shouldn't hurt anything. I don't think it will compromise the strength. Anyway, when you start to fit these pants, most of the cutting is done out of the front pant. You certainly can cut too much off, so you need to be careful. But the wheel pant gear leg intersection fairing is pretty large and can cover quite a bit of mistake there.
I set the two halves together and duct taped them. The plans say to put in 5 or 6 #8 screws, and don't get too close to the bottom. That just means drill your hole where you can get a good straight shot at the screw with a screwdriver. For fitment purposes, I actually only put in 4 #40 clekos. It's possible that I may not want to use the holes I drilled in the end. I can fill them easy enough if I need to.
I did not use a 1 inch spacer on top of my tire. I used a 5/8 inch thick piece of scrap wood I had laying around. It was fairly long, so it probably held the pant up more like around 3/4 inch. I duct taped it to the rubber.
During this fitting process, I had the fuse hooked to a hoist. I was moving the whole thing up and down off the gear so I could see what what going on under the pants and mark them. What I found was that most of the marking and therefore cutting that I did was at either end and on the outboard side of the tire cutout at the bottom of the wheel pant. Even after bending, the bracket holds the wheel pant quite a ways out away from the tire, so there's quite a gap at the bottom on the brake caliper side of the pant. I had to cut more than 1/2 inch at the ends, and every bit of 3/8 from the outside at the tire opening of the pant. I used my air saw to cut the tire and axle openings in the pants.
I stopped cutting everything when I could put on both pants clekoed together with the block on top of the tire, and the pants would move around somewhat easily. I have to adjust them to go with the slip stream. First, I had to make them easy to get on and off and get some clearance at the opening for the rubber. In the beginning, the pants were wedged against the bracket and the rubber, and felt bound up. Now they sort of rotate a bit, and I can put them in a range of positions. Now they are probably ready to line up with the slipstream. I'll come back to these later on, maybe months from now, and line these beauties up!
I visited Jim Winings in Indianapolis and he has a cool set of pants that may essentially be "one offs". They are two piece pants as well, but the separation is around the tire inboard over the brake calipers. So looking from the outside, you don't see any seams. Those babies are supposed to be the slipperiest pants you can find. Jim described the features, which include a much smaller trailing edge "tail fin". When you look at the position of the pant above, you notice it looks pretty nice. Keep in mind that my tail is up on a sawhorse and if it was on the tailwheel and I hit a bump, I would easily scape the bottom of the fin. I may just fill in the back of my wheel pants from the inside with flox and grind them down to the size of J.W.'s, which would make them 2/3 to 1/2 the height. Less drag? Don't know. Dragging less? Absolutely!
I took my legs over to Plainfield, Indiana and had them cut down. I also bought the Airkit LLC shortened gear socket (foot) that has a repositioned mounting plate. This plate significantly inproves wheel alignment (toe in and camber) over the stock sockets (feet). The kit also shortens the titanium gear legs and takes a lot of the jelly wobble out of them.
The alignment process starts when the Rocket is on the gear legs. The wings and everything that will be on and in the plane when flying should be added. In my case, I've been waiting over a year to get to this point. The wings are finally on the airframe out in my hangar. I'll put all the parts on that I can, then salt bag extra weight onto the plane to simulate my 200 pounds and full fuel (typical "flying weight"). I actually used 40 pound salt bags.... 5 to simulate me, 4 on each wing for fuel and stuff, 1 in the back seat for stuff, and one over the engine mount to simulate the cowls, spinner and oil in the engine.
I have some 1/4 inch aluminum plate left over from my tail feather jig. The plan is to grease the bottom of a couple wheel sized plates, and the floor, and slip a plate under each tire. With the added weight and some coaxing, the plane will come to rest in it's aprroximate taxiing stance. Then it's just a matter of marking the orientation, hoisting up the airframe and removing the legs, then center drilling for an attach bolt after assuring that the gear feet (sockets) have the pads aligned at ZERO toe in and ZERO camber (based on extended airframe and wheel centerline marks).
My foldable hoist (Harbor Freight) wasn't tall enough to get over the propeller and lift the airframe high enough to get the wheel assemblies onto the landing gear legs. I called my old buddy Keith Welsh and borrowed his "industrial size" hoist (which we used to get the airframe off of his trailer when I brought the fuse to the hangar). That hoist had more than enough ooomff to get the gear legs up. I pulled off the OEM gear feel and tossed them aside. The right wheel assy went on just fine, but I have to "coax" the left side a lot to even get it part way on. Out comes the files and sandpaper.. and a dollup of grease. After that, no problem!
Originally, I was going to use lasers along the wheels (tires actually) to check the alignment. That's just not practical. However using a laser to get the centerline of the ship IS VERY practical. I centered the ship up in my hangar over the center seam in the concrete floor. Then, I centered my Dad's laser (thanks Dad!) on the seam and shot it along the floor and belly of the ship, all the way to the back of the hangar. With the plane's tires sitting on greased plates, it was easy to center the beam on the belly seam of the fusleage as well as the tailspring and tire. Now that I know the ship is centered, I can work on the wheels. Of course you don't really need to use the center seam on a floor, you can put the laser anywhere you want arbitrarily, and center it up on the ship, and check you measurements agains the beam. I used the BEAM, not the floor seam to make measurements.
Instead of a laser, I used two peices of aluminum angle I had in back stock. Each was over 4 foot long. To prop them off the floor, I used 4 oil filters (still in the box) at the outer ends of the angle and a brick laying against the angle to make sure it stayed agains the tire. After that, it's a one man job using a large tape measure and double/triple checking measurements just to get everything equal and centered. You want a rectangle, not a parallelogram! Equal AND centered to make it all "square".
It wasn't hard to rotate the wheel assemblies. I used a dead blow and tapped (OK, BANGED) the rubber a couple times to coax the wheel around on the gear leg. Very small taps on the tire with my palm was all that was necessary when I got it down to about 1/8 inch. Once I thought I was finished, I took a break, then came back and double/triple checked my measurements. Good to go! So I made some marks along the leg and foot to index the alignment between them for drilling on the bench.
As an afterthought, I removed all the ballast and checked the aligmentment again. The index marks had not changed, but without the nearly 600 pounds off of the airframe, the tires scooted the greased plates about 4 inches! A quick measurement between the angles showed that there was now about 1/8 inch of TOE OUT! Let that be a lesson to you boys and girls, if you shoot for "zero/zero" on your wheel assemblies, it never actually stays that way. All you can do is guess at your flying weight and hope for some "fudge" when you are flying light. Toe out is not particularly good on a high speed taxi (landing). And flying a little heavy in MY Rocket will probably make landings a lot easier.
Time to hoist up the airframe again, remove the gear legs and wheel assemblies, then drill them together on the bench. That wasn't too tough. Had some help from my flying buddies. Ruined two bits going too fast through the titaium. Man, does that stuff get hot, even with copious cutting oil. Since the gear legs have the dampers on them already, and since the leg diameter is larger than the foot diameter, getting the leg to sit perpendicular in a drilling jig was tough. So the bolt holes didn't end up perfectly centered, but they are really close. I filed off the lip around the drilled holes, lubbed up the parts to keep corrosion down (that steel foot wants to rust pretty badly!), and reinserted the leg/wheel assemblies into the engine mount. NOW it looks like an AIRPLANE!!!!!
Brake Lines & Bleeding
Summit Racing has some nice AN fittings and braided stainless hose. The Grove brakes as supplied need a 1/8 NPT to -4 AN fitting. I was going to use a steel fitting, but opted to use a supplied 90 degree aluminum fitting down at the caliper. In fact the only steel fitting is the bulkhead fitting through the firewall.
Locating the bulkhead fittings was a little tricky. I was trying to figure out how to install a parkling brake valve in the brake system. Icouldn't figure out where I wanted to put the push pull cable because the arm on the valve seemed to work the opposite of what direction was convenient. Finally I stuck the valve assembly on the top of the footwell in the firewall, directy in the center between the brake cylinders. Then, I needed to determine access to that valve and run high pressure lines to the other side of the firewall. I was going to run the hoses outboard near the sidewalls on the firewall, but decided instead not to have long tubing runs over or around the pedals, and just went through the center of the footwell. The next decision was where to run the lines and where to locate the bulkhead fittings in the footwell. Essentially you have to decide top or bottom. I decided to run the bulkhead fittings just above the level of the engine mount bolts in that area. The bulkhead fittings are then over the mount cross tube and away from the fuel pump and the exhaust pipes and hangars. That makes the braided lines that run along the legs longer, but overall a simpler and more convenient.
The wheel pants are pretty tight around the wheel/tire assembly. It was going to be tough to use a straight fitting in the caliper. A 45 fitting probably would have worked, but I didn't have any on hand. So, 90 degrees it is. Then a 45 degree fitting on the -4 hose end at the caliper. The braided line will run along the leading edge of the gear leg, up over the engine mount leg tube and attach, then up over the middle horizontal mount member and attach to the bulkhead fitting with a 90 degree hose end. Summit makes hose ends in red/blue and anodized black. I decided to use the black for the brake lines. A, because they look cool, B, because the caliper gets so dirty anyway, and C, to differentiate between the red/blue braided stainless fuel lines.
The 5606 FAA/PMA brake fluid has worked very well for most light planes for decades. It does have a low flashpoint, and if you have a hydraulic leak, like onto a red hot brake caliper, it can catch fire. Actually it looks like all brake fluids can catch fire, it's just a matter of temperature. The consensus amoung experimental builders is to use synthetic ATF (automatic transmission fluid), which can tolerate nearly double the heat before reaching flash point. Also, it is compatible with the O rings in the Grove brake calipers. Auto Zone supplied me with 2 quarts of Valvoline synthetic ATF. Turns out that it's red and looks just like 5606. Sure doesn't smell like it, though. They both are nasty.
Once the stainless lines were along the gear legs and attached to the fittings, and the nylon brake system inside the cabin was ready, it was time to fill the sytem and pressurize the brakes. Sadly, it's not as easy as just filling the reservoir and pumping the fluid down. Nope. You gotta get a bleeder adapter and push the air out of the high pressure side of the system from the bottom up. It's an easy job, albeit often messy. (and it did not work for me...)
Bleeding the brakes turned out to be tricky, but easy once you know the secret. Well, once you stumble onto a method that works. Slow, traditional bleeding from the top down? Nope. Pressure bleeding from the bottom? Nope, didn't work. What my friend Jeff Tucker finally suggested was to fill the reservoir, hold pressure on the pedals and then quickly open and shut the bleeder valve at the bottom of the calipers. Once we got the rythmn down, it only took about 20 minutes to do the whole job. Took 3+ hours total to figure out what didn't work! DOH! Once you get that solid feeling brake pedal, the satisfaction is tremendous!
Gear Leg Fairings
Now that the wheels and brakes are installed, it's time to close everything in. The wheel pants will need a little extra trimming around the gear foot bolt and the brakes lines/fittings. After that, it's a matter of positioning the spats and leg fairings. This will be a little interesting because my gear legs are 3 inches shorter than stock. That means I'll have to trim the leg fairings about 3 inches at the top. I hope that doesn't create TOO big a gap at the gear leg/fuselage fairing.
Let me continue by saying that right off the bat, you need to cut like 6 - 8 inches off the top of the GLFs. And contour the top cut to parallel the lower fuselage. After that, I split the "spats" which fair the junction between the wheel pant and GLF and the GLF and the fuselage. My idea is to work from the top down.
Once the engine cowl is in place, it's pretty easy to take the upper spat and coax it to a stable and good looking position. I drilled each once of these in 3 convenient places into the cowling, but NOT into the metal fuselage. I'm going to try to combine some fasteners into the fuselage with the wing root later. Anyway, once the upper fairing is clekoed in place, then I took the cut GLF and trimmed it some more. So far, the GLF sits inside the upper spat about 3 inches. When I put the wheel pant fairing (lower spat) in place, it looked pretty good all together! I did NOT trim the bottom end of the GLF AT ALL! I kept trimming the top of the GLF until the lower GLF actually sat in that notch in the titanium gear leg. That ends up putting the GLF substantially inside the necks of the spats, but still short enough not to interfere with the wheels/brakes or fuse during service.
The TE of the GLFs have to be cut. Even the molded cut line is not enough, but it is close. Once I trimmed the GLF at each end's TE, just enough to fit in the spats, I observed how everything sits together. My theory here is that if the upper fairing is right, and the GLF is lined up using the upper fairing, then the lower fairing should be easier to locate, and maybe that will help locate the wheel pant. Again, trying to get it all to "work together" (orientation) from the top down.
After I had already been flying my Rocket about 15 hours, and after test flying the wheel pants, I decided to trial fit the rest of the landing gear fairings and go for a flight. I located the upper intersection fairings (UIFs) where they positively absolutely fitted against the cowling and the belly of the airframe, and clekoed the ULFs in place. The wheel pants were in place (with the wheels/axles properly re-aligned zero camber, zero toe in). I trimmed the scored line on the GLFs and put them over the legs and dampers. I taped the GLFs closed. They actually WANT to go into position fore and aft. I DID NOT FOLLOW THE MANUAL. I figure that if my dampers are right, and the GLFs want to sit where they want, and I have the GLFs trimmed and taped VERY SYMMETRICALLY, then you don't need a plumb line, and make measurements, blah blah blah (well, I was hoping I wouldn't need to go back and do it the hard way....).
The GLFs only wanted to scoot fore and aft over the legs and dampers, not change "flying angle". I taped them with some duct tape (closed the trailing edge) and then wrapped the right leg with shipping cling wrap, then taped some more. I put the lower intersection fairing in place and scooted it around until it felt like it was where it wanted to be. Then I drilled the LIFs to place and clekoed them, AFTER drilling the top of the LIFs for one of the wheel pant screws and screwing them together (just that one screw on each pant/fairing).
After the intersection fairings were in place, I went around to all the clekoes, and replaced them with pop rivets. So the intersection fairings have one screw and a slew of blind rivets (temporary, non structural).
Now that the intersection fairings are set, I went back and taped the GLFs as far forward as possible, trying very hard to give them positive seating in the fairings at either end. I used duct tape for this. Several pieces, in a criss cross fashion, to be sure to hold the leading edges tight together (the trailing edges of the GLFs are not the same as the intersection fairings, not yet, anyway).
Note that the GLF is supposed to ride inside the other leg fairings, but for now, I taped them together. I wanted to fly the plane with them in a test position and make sure that I didn't cause any whacky turning tendencies or anything.
Near as I can tell, after a 2.2 hour test flight with the gear leg fairings just taped on, the plane flies the same.... except faster!!! I like what I have, and once we are closer to determining what we want to do with the experimental damper/strut antennas, I'm going to drill the clekoes, rivet in some plate nuts, and screw everything together. I'll also put some UHMW plastic tape on the ends of the GLFs where they are supposed to ride inside the other fairings. They of course need primed, too.
Gear Leg Nut
One thing I nearly forgot to do was to re-torque the titanium gear leg nuts! And of course they have to be drilled and safetied. The first nut I just decided to drill through every other corner and keep my fingers crossed that I'd have a good location to safety. It worked out, fortunately. On the second nut, I just torqued it down, marked the corner next to the engine mount tube I was going to use to safety, then drilled just that hole. Well, that didn't work because I got confused and drilled the hole to the "loosen" side of the tubing, not the "tighten" side of the tubing. Fortunately, I realized this before re-installing the nut.
After drilling the first three holes in the nuts, and breaking three bits (I was doing this with a cordless drill), I was getting a bit frustrated. Finally, I went up to a bit that was about 3 times the diameter that I needed. And sharp. And I used cutting oil. First I directed the bit perpendicular to the hex side of the nut, then as the bit went deeper, I slowly turned the drill to drive through to the next face on the nut. The final two holes went very quickly and easily. The trick was to slow the drill WAY down.
Another thing that I added to the mix was some nylon tubing. I cut off just enough to go over the .041 wire and looped the engine mount. The one in the pic to the left I did by hand through the nut, then used twist pliars to pigtail the end.
The tab washers that come with the legs and nuts had to be bent down over the engine mount where it would interfere with the safety wire. In fact I wasn't able to get onto any tab to bend up agains the flat of the nut. The engine mount tube where the gear leg fits in is round anyway, and the tabs aren't long enough to go between the support tubes. So I just left it alone except where I needed to bend it out of the way of the safety wire.
My theory on this problem is that my plane, especially with me in it, weighs a lot more than Jim Winings and his plane. Jim is the guy who cut and rewelded his gear leg sockets to correct the alignment and shorten the "foot" and gear leg by 2.5 (or was it 3?) inches. I shortened my gear legs and used the gear sockets that hold the axle from a kit designed by Jim. He is also the guy who noted my tires showed a LOT of negative camber when I was taxiing in front of him. Dammit. I thought I had done a fantastic job with my alignment. Well, maybe I DID!
I think that given the fact that my EVO is heavier than a standard Sport F1, plus I'm heavier than Jim, plus I have a dual battery system up front, I think I just have a bunch more weight on my plane than Jim does. I think it was inevitable that under similar load conditions (single pilot, full fuel), my plane was going to end up with negative camber using the alignment that Jim used on is Sport wing Rocket, and gave him zero zero alignment.
My toe in is ZERO. That's good. Zero toe in and Zero camber is what we want for best all around use of our tires. The nice thing about ZERO ZERO is that it doesn't make any difference whether your tail is up or on the ground, it's stays zero zero (or darn close to it). Now this does not take into account a lot of variables. Mostly, I'm talking me in the plane with full fuel. Heavier loads (or lighter pilots) are going to change the wheel position because of the flex on the gear legs. However, let's keep it simple. Now if your camber or castor are not zero zero, then as the plane's orintation changes from tail high to 3 point, then the tire orientation can change a BUNCH!
My goal was to just change the CAMBER, and not add any toe out or toe in. I wanted the fore and aft alignment of the tires to stay the same. So I was looking to get some shims that really only changed the dimensions in one flat plane. "Cessna" shims (and the shims I used on my Citabria) are pre-drilled and change both camber and castor in varying degrees. I didn't want that. Randy Pflanzer turned me on to the fact that he used RV8 shims to align his wheels.
Vans sells shims for $8 each. Pricey. But less than Aircraft Spruce's Cessna shims for $45 - 135 a piece! The Vans shims are simple, small aluminum plates. Undoubtedly they are simply cut/machined from a chunk of billet. The 1 degree shims are the same thickness at the top compared to 1/2 degree shims. The 1 degree shims are, however, about 1/2 the thickness of the 1/2 degree shims at the bottom edge. And they are only angled in one plane, so they can change camber OR toe in, not both. Well, you can use a combination of shims to change both aspects of your alignment, but each shim can only change one aspect of the alignment.
I had used shims before, but not like these. I had used predrilled "Cessna" shims that simply bolted into place. The Vans shims are plain flat (angled) stock. Undrilled. Which in this case is good. Although there is a square bolt pattern for our Grove axles, the gear leg holds the foot at a funky angle, and I'll bet that the gear leg andle is specific to the Rocket. So pre-drilled, "pre-made" shims (unless made by Team Rocket... which they really don't) just won't work.
The sims didn't come with instructions, so I guessed. Can't be that hard. Made my own rules as I went along Vive La Experimental!
Again, my toe in was ZERO, and I wanted to keep that measurement. That measurement was checked with the tail DOWN. Mark Frederick wants you to set your wheel alignment with the tail in the air. Jim Winings wants you to align your gear with the tail in three point. Mark wheel lands. Jim 3 points. They are BOTH right. Again, if youshoot for ZERO ZERO, it doesn't matter. My camber was negative, with the tops of the tires tilted inboard at 2 and 3 degrees (give or take) on right and left, respectively.
Follow along with me.... SO, the measurement from the middle of the front of the tires is the same as the middle in the back of the center of the tires. Now let's assume that I have the wheels centered with the centerline and I'm not driving some trapezoidal aligned, side shifting catywompus Rocket. I'm not. The thing tracks straight as an arrow. The front at backs of the tires should not change. My goal is to just tip the tops of the tires outboard and not change the toe in. Flat shims, inserted "squarely" to the floor should allow me to do this. Again, the goal is ZERO ZERO, I want them square. They are already ZERO, so I just need to negate the negative camber.
I started on the right side. First I removed the brake caliper. Then, I used my hoist and a motorcycle handlebar tie down loop (big beefy one made by Harley) on the low side of the gear socket bolt to lift the gear leg. I removed the wheel/tire assebly, then the AN4 bolts and axle. Just to be safe, I put 4 2x4's under the fear foot (socket) in case the hoist/loop slipped (it never budged). I used the 2x4s as a guide to show be what square to the floor would be. This is a very precise science, not an EXACT science, so let's not get too anal here. I set the bottom edge of the shims on the 2x4, centered the shim between the bolt holes, and marked to cut the notch for the top bolt.
A note here. These shims are not going to be drilled. They are notched. They do not cover the entire mating surface of the axle, they only fill in the space between the bolts. Note the picture. Also worth mentioning is that the bolt holes are offset, because the gear legs sit at a wonky angle.
Once I had the shim(s) notched for the top bolt, I double checked that the lower edge was parallel to the flat surface of the 2x4. I want these shims SQUARE to the floor! Next, I marked the bottom bolt hole on the shim and then notched it. I used a round file to finish the notches so that the shims were not too loose and kind of stuck in place between the bolts. Then I marked and notched for the other two bolts.
After notching 2 each of the 1 degree shims for the right axle, I bolted everything back together. Then I notched 3 degrees worth of camber shims for the left wheel and bolted them up. Easy, peasy. Took me about 3 hours to figure out what I was doing and to finish the project. You can probably do it in half that time!
Now that I have ZEROED out my camber, time to get the plane out and taxi it, then check it again. I bought some 1/2 degree shims just in case I need to tweak the camber more ( or maybe even correct toe in, which I doubt). If anything, since at the time of this writing my Rocket has neither paint or interior, and since I plane on occasionally carrying a backseater, I hope if anything I end up with slightly positive camber. Since it was 16G32 today, I decided not to roll the plane out. I was afraid it would launch all on it's own, unintentionally.
Another note: I changed the right axle bolts to AN4-14 and the right axle bolts to AN4-15. Since you are increasing the distance between the Grove axle and the pad on the gear leg foot socket, you have to increase the length of the bolts slightly.
You might be able to tell in the pic that the axle sits a bit differently against the pad on the foot. When I made the change on both axles, you could really tell that the tires sat in quite a different orientation.
Note that the middle bolt (most noticeable) could have been dropped to a AN4-14 instead of the 15 that I used. It probably would have still had one thread showing. But I decided to just use bolts of the same length all around for simplicity sake.
After confirming that the alignment is complete and correct, I can go back and finish the installation of the gear leg fairings. If the wheels are not correctly aligned before you finish the fairings, you would have to go back and re-position and re-drill the instesection fairing at least. You might even have to change the main gear leg fairing.
Now I hope my tires wear more evenly and more slowly. Also, the plane should be a little easier to push around by hand.
Bleeding the Brakes
Nothing earth shattering here. But I did find that I had trouble bleeding from the bottom up with a pressure bleeder. Our friend Chad Williams, RV6 builder and IA, stopped in to my hangar while Curly, Moe and Larry were trying to bleed the brakes on my Rocket. I did a poor job on one of my nylaflow lines and the compression fitting popped loose. After replacing the line, I was in the cockpit pumping the pedal as one friend was watching the reservoir, and the other was opening and closing the bleed screw. Well Chad suggested getting some "fish tank hose" and just looping it into the reservoir. He said you might need to safety the clear flexible hose onto the bleed fitting to keep it from splooging or leaking air. At the time, I just happened to have a small roll of that clear poly tubing in the hangar, so we went to work.
With the clear hose looped up and set into the reservoir, it was just a matter of watching for the air bubbles to come out of the fluid, and making sure the reservoir doesn't overfill or empty (a 6 foot hose holds more fluid than you think). But you merely pump the pedal like a mad man and force the air bubbles out of the lines. Nice to be able to see them in the clear tubing. After a while, the pedal starts to feel moderate resistance and no more bubbles can be seen in the pretty red synthetic ATF fluid. At that point you just close the bleeder screw and remove the clear tubing. The pedal will feel like a ROCK! Works like a charm. Thanks to Chad for the recommendation and for changing my technique. With this technique, it'll actually be easy to bleed the brakes all by myself. Sweet.
I covered my parking brake installation in the Fuselage 3 section. The parking brake valve was bolted inside the cabin on the top of the footwell in the firewall. It sits in the center of the footwell, between the rudder/brake pedals. I installed a T handle to close the valve and lock the brakes. The handle (from Spruce) resided on my center console, near the fuel valve switch. The parking brake is a simple system, the cable merely pulls the valve arm 90 degrees to lock pressure in the system. Press the brake pedals, twist the handle and pull it, twist it back and pressure is locked against the brakes. Kinda nice on windy days and slopeing ramps.