Help? Landing Gear (Mis)-alignment

[NWade]

Don't feel too bad. I had mine drilled and sitting on the gear for a year during the build before I realized I had the toe in and toe out angles reversed. I found the 2x4 method to actually work alot better than the way the plans call out how to set the angle.

Keith -

But don't you need to ensure there's no (or nearly no) weight on the gear for that method?
Also, if you let the legs "hang" using the 2x4 method, with the wheels on the ground, you still wind up with potentially a lot of empty space inside one of the sockets if your gear legs are sticking down different distances from the lower longerons (like mine) - right? I mean, I guess I could flip the fuselage and use that method to confirm my alignment problem; but if it still exists then I've still got to figure out the right corrective action - no?
...BTW I'm talking this out, not trying to push back against your suggestion - let me know if I'm missing something! :)

Thanks,

--Noel

[N111YX]

As the "inventor" (or at the very least default adopter of the concept because of jig slippage) of the 2X4 method, my idea was to use enough weight of the fuselage, perhaps 5% or so, to lock things in adequately for drilling. This is done by partially lowering the airframe into the channels via jacks or, if the engine is not installed, perhaps the weight of the fuselage itself sans jacks would not be too heavy to be excessive for the measurements to be accurate.

I don't think 25 lbs or so loaded per wheel will affect the called out measurements enough to matter considering what they'll be loaded to later on.

Best of luck :)

[NWade]

Just to close this out, for posterity:

After re-measuring a bunch more, I confirmed that there is a slight (~0.7 to 08 degree) misalignment between the two main gear tubes on my engine mount. The geometry works out such that when you multiply that over the 34 inch run of the gear legs it accounts for my measured misalignment in gear height and fore-aft position.

After exchanging some detailed emails with Kerry & the Sonex Tech Team, they concur with my ideas for "fixing" the issue.
Option 1: Try to use my bandsaw to cut about 7/8" off the "tall" gear leg.
Option 2: Slide the "tall" gear leg up in the engine mount by 7/8" and drill a new upper attachment hole.

There are two side-effects with either solution. First, I note (as a former chassis/setup guy for NASCAR and SCCA race cars) that the gear that I "shorten" (measured along the centerline of the gear leg) will have a higher effective spring-rate when compared to the other gear leg - since it'll have a shorter bending moment under compression and side-loads. I think this will be a minor effect, however, and is not worth worrying about except during an extreme bounce/prang where I'll have my hands full anyways! :P
The second issue is that the change I make to the leg length does not change the gear leg angle itself. One gear leg will still stick out slightly more in the lateral direction than the other leg (due to the engine mount tube misalignment). While changing the leg length means that the airplane will sit level on the ground, one wheel will be farther from the centerline of the aircraft than the other, by about 3/4". Word from the Sonex factory is that this difference is not a concern, given how the gear legs will flex under load and change the effective track/spacing between the gear during normal operation. I still want the toe-in to be set relative to a line that's parallel to the fuselage centerline (so that the aircraft doesn't try to crab on the ground), but otherwise I'm OK.

The idea of cutting the Titanium on my small benchtop bandsaw is daunting, so I'm pretty sure I'm going to drill a new upper mounting hole in one leg. Given my previous experience this will cost me 1 broken drill bit and 1 smoked bit (despite being careful and using Cobalt bits); but it be the last I have to mess with it!

--Noel
Sonex #1339

[sonex892.]

The idea of cutting the Titanium on my small benchtop bandsaw is daunting, so I'm pretty sure I'm going to drill a new upper mounting hole in one leg. Given my previous experience this will cost me 1 broken drill bit and 1 smoked bit (despite being careful and using Cobalt bits); but it be the last I have to mess with it!

--Noel
Sonex #1339

Noel.
To get the spec'd length and maximum insertion at the axle end, I trimmed my legs off at an angle. I used a hacksaw, real slow strokes (slower than my band saw) and lots of cutting fluid. It wasnt that bad and was over in minutes

[dtwolcott]

Nwade
I don't know if you solved the problem of one leg too long. If not I figured out my problem. The leg would not go all the way into the axle tubing because the weld that went around the tube close to where the hole is created some raised weld spots inside the tube. This stopped the leg from bottoming out. This caused the axle to be 3/4 inch farther from the fusalage than the other one. Just found this out today.
Don