Main Gear (taildragger configuration)

Here's how the Cleveland wheels mount to the Diehl gear. I really hate the way those bolts almost hit the brake disc. In fact, I had to take a grinder to my bolt heads to keep the disks from being scored. The compromise is locating the bolts so that there is enough edge distance around the bolts at the bottom of the fiberglass legs to prevent tearing them out, or the bolts hittings the discs.

This is the Diehl gear casting and leg installed to the front of the main spar. One question you might ask yourself at this point (now that you've glued and bolted the leg to the casting) is "how can I sand the correct contour into the leading edge of the airfoil with that gear leg in the way?". Were I to do it again, I'd flox nutplates to the back side of the casting and leave the leg removable so that the contour could be sanded and then the leg reinstalled. The black thing to the right is the landing light.

Here you can see that I had to clearance the lower gear brackets so that the caliper could be mounted almost horizontally, otherwise, it would be pointed down toward the ground and almost dragging. The brake line will running around in a 270 degree circle to relieve binding and allow a little flexing.

I've been worrying about prop clearance, since I want to swing a 54" prop and my Corvair engine's thrust line sits 2" below the longeron. That sounds like a lot, but I've seen drawings in the Newsletter that indicate that the thrust line was set to 2.375" below the longeron on at least SOME drawings that came out of the "factory". Troy swings a 60" prop with his C-85, but only has about 4" of ground clearance, but then he normally flies off of asphalt, and he's a great pilot. I'm planning on landing on some grass (although it's kept like a golf course), but would like to have the extra clearance. And I'd like a little taller stance to come a little closer to a full stall landing.

Anyway, the easiest way I've come up with to do that is just add 3" to the length of the lower gear leg bracket (in the vertical direction), which also improves the angle that the gear intersects the wheel fairing and should reduce drag a tad, despite the extra height. There will be an offset so that the bracket will align with the gear leg, rather than being skewed like the Diehl brackets end up. And this will also solve the problem mentioned up in the first paragraph, where the bolts are in such close proximity to the discs. The bolts will be nowhere near the brake disk now.

If I had the chance to just start over again, I'd probably buy Grove Aircraft's solid aluminum gear for about $550. It's already 4" taller than the Diehl gear, and they will alter their standard gear to whatever specs you request. I think I'd ask for gear that's about 6" taller than the Diehl gear, or another 2" taller than Grove's usual height, for even more prop clearance and the ability to do full stall landings.

Standard KR main gear is the "Lamb" tire (now made by Cheng Shin) 11x4.0-5, which is a little shy of 11" diameter undeflected. I bought a set of 5.00x5 tires for my Clevelands in the beginning, but they looked like Tundra tires on the KR, so I gave them to my brother to use on his C-172.

Update-March 22, 2003 - With the engine mounted, and three concrete blocks sitting on each stub wing to simulate the weight of wings and fuel, it was time to check the wheel alignment. Tony Bengelis says shoot for straight ahead in normal attitude (tail high, for a taildragger), and no camber. I thought I'd check to see how close I was going to be, given the "hail Mary" methodology of mounting lower gear attach brackets to gear legs.

I used a $12 Harbor Freight laser level to project a line that I could measure from. This particular level has a removable collimator that splits the pinpoint laser dot into a fine line that is projected at about a 90° angle for a distance that easily visible 50 feet away in darkness. After raising the tail to level the plane, and rolling the plane a little to let the tires get realigned, I clamped the level to the brake disc on one side, leveled it, and turned out the lights.

I measured a distance 20" away from the tire and put duct tape on the floor to mark where the line intersected the floor. I then measured 277 inches further away, and marked another piece of duct tape with the beam's path. I then moved the level to the other brake disk, and repeated the procedure. With the lights turned on, I measured the distance between the beam at the start point (20" from the tire) and 277 inches further away. I came up with a convergence (they got closer together) of 11 inches. I divided 11 by 277 and hit "inverse tangent" on the calculator, which yielded a toe-in of 2.27 degrees. Actually, I didn't have to bother with that. It's just a ratio thing to determine what thickness a shim would need to be. 11/277=x/2.5, where 2.5 is the width of the lower gear bracket. That tells me that I need a shim that is .0993" wider on one side than the other. But since I can split the difference between the two sides, I need a .05" shim on each side. I could probably put a light washer under the front two axle bolts on each side to do that job, but I'll probably get a machinist to mill a shim for each side. That way I can also cure the camber difference that I have between each each side. These are also supposed to be vertical when landing, and mine are 2.9 degrees on the pilot's side, and 1 degree on the passenger side. I'll have to figure out what I need exactly, but I'm confident that I'll get it pretty close.

I also taped the laser to the top of the vertical stabilizer and projected a beam across the centerline of the firewall, across the same 277 inch line. I marked where it intersected the floor too. This allowed me to determine that my centerline is only off by about an inch over a distance of 80 inches, which is a deviation from straight ahead of only .7 degrees. Close enough for KR work! Later, after the engine was completely installed, I used a plumbob from the center of the prop hub to find the CL up front, and from the tailwheel spring to define the rear line, and reverified the aircraft centerline. The two were within an eighth inch, so I'm pretty confident about that.

There's no telling how many ground handling problems are caused by something as simple as imperfect alignment, and it's too eazy to check and fix to just leave it to chance.

November 2004 , Now that the wings are attached, the engine is completely installed, and almost everything is exactly as it will be for flying, I've revisted the alignment so I can do the final adjustment. A funny thing happened with the fuel tanks 3/4 full and 150 pounds of pilot in the left seat...the excessive camber in the pilot's side almost went away! So now all I have to worry about is the toe-in, which also improved with weight. It's now only 2.09 degrees, so a simple 1/32" shim on one side would correct it by 1.33 degrees, reducing it to .76 degrees, and still very close to being aligned with the fuselage. That's definitely close enough for KR work!

Updated August, 2007
I have to say that I can't imagine an airplane tracking any better, or being any easier to takeoff and land with, than this KR has been! I land on grass quite often, and even with 12" grass, I've yet to have any kind of problem with the 11x4-5.00 tires. But I've landed with a flat tire three times so far in 460 hours of flying and over 1000 landings (triple that if you count bounces).

As I was getting ready to fly to the Corvair Wings and Wheels thing in Alliance Ohio, I noticed my tire was low. I had a can of "AirUp" from Walmart on hand for just such an emergency, and put about 3 ounces of the can into the tire. It filled it up and sealed the inside from future leaks. I'd been told that this would lead to a big imbalance in the tire, and the gear would shake a lot on takeoff. Sure enough, it did...but only the first time. On subsequent takeoffs and landings (and I've done at least 25 since then) it's been as smooth as ever, and the tire is still holding air just fine. The beauty of this solution is that the stuff is still in the tire, and any more tube pinches will probably be sealed before I land. To me, this is 3 ounces of insurance, and I'm quite happy to carry it around with me inside that inner tube. In fact, I'd been carrying a full can for a year in anticipation, so it will actually save me some weight by just carrying three ounces in each tire!

This has worked on my mountain bike for about 10 years now. Before that, I got 2 or 3 flats a year due to thorns, and I got tired of pushing a bike around. Yes, the KR tubes/tires are thoroughly talcum powdered and I keep them inflated to about 45 psi.

My chocks are a sort of go-no-go gauge that makes it easy to tell if my tires are a little low. I put them under the brake disk, so if the tire deflates between flights, it's difficult to get the chock out, and even I can tell they're low. These chocks are my home hangar chocks. "On the road", I use two thin aluminum angles I keep in my flight bag...or a nickel will do too...

Here's how I jack up my airplane when I'm working on it in the hangar. "On the road", I just find somebody to crawl under the spar and lift with their back while I change a tire or something (I've only had to do that once, however). That torn wing/leg fairing was done on my first flight, where I tested the gear with a 5.5 g landing.

I finally got around to doing the gear leg extension thing. What I expect from this is a lower landing speed due to the higher angle of attack (getting closer to full stall and 4 more inches of prop clearance so I can spin a longer, more efficient prop. Now I can move from a 54" diameter prop to a 58" diameter prop, and still have an extra 2" of ground clearance.

There's 3.75" of vertical lift here, which is equivalent to gear legs being 5.3" longer (almost as long as Larry Flesner's and Jeff Scott's gear legs). I also slid the wheels back a tad to see if that'll improve three point landings. The caliper is awaiting hookup in this picture. The extensions are made of 1/4" 4130 steel, TIG welded, and powder coated, hacked out in my basement (and it shows). These come with a 12 ounce weight penalty each, but I could've (and should've) shaved some of that off.

As you can see here, N56ML got a lot more "proud", and looks kinda "bad" to me! Taxi visibility will get worse, but that's OK, because it just means I'll have to sit up on the seat a little higher. It does resemble Larry's and Jeff's airplanes. Now wheel pants and gear leg fairings can commence. I'll let you know if the wheels fall off...

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Email me at N56ML"at"hiwaay.net