Onex main gear

[13brv3]

My new gear showed up yesterday via UPS ground. The box isn't all that big, and certainly not that heavy, but it was still $120 shipping.

Would other Onex owners take a look at the gear and see how much the center horz section is bowed? Since it's bolted through to the angle that's inside the floor, when the center of the gear bends, it also bends the floor. On mine, I'd estimate the center of the gear is 3/16" to 1/4" lower than the left and right ends, and I can only imagine what happens with any landing force. It really seems wrong to me to have your landing gear constantly flexing the floor of the fuselage.

Most gear like this is mounted only at the left and right ends, and with a clamping type radiused block. The way this is mounted, the main landing force probably exists on those two washers that are between the outer bolts and the fuselage. When I remove mine, I fully expect to find significant dents in the skin where those two washers are being smashed into the aluminum. At the very least, I'll make a full length plate for those outer bolt locations to spread the load, and I'd highly recommend anyone who's still building one to do that as well.

[13brv3]

How did others handle the brake lines along the rear of the gear legs? My original gear already had holes drilled like the plans show, but 2 instead of 3. As suck, I needed to use tie wraps between the two to keep the line from flailing around. With the new gear, I don't really want to drill holes, though I've seen that it doesn't become the weakest portion of the gear leg.

I'd really like to just wrap the gear in something to hold the line, but anything you put there seems like it would be a problem later. On an RV-3B, I temporarily used tape of various types, and it was never good once the sun and age got to it. How about some sort of vinyl wrap like they put on cars?

If I can't find something long lasting and not super ugly, I'll end up going with holes and clamps. I'd probably opt for using round head screws rather than countersinking the gear leg to preserve some strength. I even thought of using smaller holes, and small tie wraps rather than screws and clamps.

Rusty

[XenosN42]

I drilled three countersunk holes in each side of the gear, as shown in the plans. Then used clamps. Worked out well.

I don't think vinyl wrap would work well for this application. The wrap gets much of it's adhesion from being stuck flat on a flat surface. If the wrap had to hold down a round tube it would quickly lift off.

The small holes and small tie wraps sounds like the best alternative to the Sonex plans method. But, when I replace my OneX gear I'd just go with the Sonex way. It works.

[13brv3]

I don't have any experience with vinyl wrap, but I would have thought it would work well for this. The gear leg is mostly flat, and it would wrap around onto itself for good adhesion. If you keep the top edge pointing aft, the airflow wouldn't tend to get under it, and it should have a good chance of success.

Most likely, I'll just hit the gear with some rattle can paint, and add 3 bolts and clamps on each side. I'm still working on the best way to support the fuselage while I have the gear off. I have a metal sawhorse but it's a bit higher than I'd like, so I'll probably pick up a couple tall jack stands tomorrow then use whatever seems to work best. Pity hydraulic hoists (jacks, or anything else) don't stay up reliably.

Rusty

[rpf]

Hi Rusty,

This is how I supported my plane when i removed the gear to upgrade to 5/8 thick 7075 aluminum.

Randy

[13brv3]

Hi Rusty,

This is how I supported my plane when i removed the gear to upgrade to 5/8 thick 7075 aluminum.

Randy

You sure didn't waste any time making that gear! BTW, what engine mount is that?

I removed the gear yesterday, and match drilled the holes for the new gear. I tried to take pictures of the bend amount for each side as well. Just measuring the angle, the new gear is 51.5 deg, and the old is now 47 and 48 deg.

Rusty

[rpf]

Yeah, I still have to match drill mine. I’m also waiting for new axles that I ordered. That mount is for an aeromomentum am13 engine.

[sonex892.]

How did others handle the brake lines along the rear of the gear legs?

Rusty

The Sonerai project I'm working on came with grooves cut into the rear edge of the gear legs. I intend use thinwall aluminium as a conduit, glued to the gear with proseal.

[13brv3]

The Sonerai project I'm working on came with grooves cut into the rear edge of the gear legs. I intend use thinwall aluminium as a conduit, glued to the gear with proseal.

I don't think I've seen the rear groove option before. I now Grove used to offer a gun-drilled brake passage in the gear leg.

I ended up drilling the normal 3 holes, but I didn't countersink them, and used tie wraps instead of clamps.

[13brv3]

I finished installing everything today. I decided that the tires and discs were fine for now, and the pucks were OK to use for a limited time. The new pucks will be easy to install, and I'll do that in the near future.

Once the plane was back on the gear, there was some good news. First, the tires are at about 0.5 deg positive camber (0.6 R, 0.4 L). This is a promising start, since the original gear was measured at 1.2 deg negative for the left, and 2.7 deg negative for the right before the plane was even taxied. It’s always possible that the early kits (SN-085) had gear that wasn’t bent correctly, and they fixed that later. I’m also hopeful that they improved the heat treatment, or changed alloys. I've never seen any comment that suggest Sonex ever made a change to the gear, and I can imagine reasons why they wouldn't make that information public if they did.

I also measured 6.25” of prop clearance in level attitude, compared to 4.5” with the old gear. This is a very nice change if it stays that way.

Naturally it's going to be raining all day tomorrow, and I work the weekend, so maybe Monday it will fly again. I'm thinking I might go back to flying the plane on at 3-pt attitude, rather than trying to land slow. Landing slow tends to be harder on the gear since the tail will always hit first. We have 6500 ft or runway, so I've got just a little extra room :-)

Attached is a before and after picture of the right wheel, and I'm guessing you can tell which is which :-) The left wheel was similar, but not quite as bad.