Onex main gear

[rpf]

Hi Rusty, I’d like a little taller gear as well. I went to Groves website to design custom gear but, because of production issues, they are not taking any orders for new gear. When I called they said they don’t see doing so in the foreseeable future. I wonder where sonex gets their gear and what alloy they’re made from?

Sonex onex gear is made from 2024. According to Grove, landing gear should be made from 7075.

[13brv3]

Greetings,

After a couple hundred landings, I can see that my main gear is starting to bend a bit. I've definitely made a few landings that were harder than intended, but they weren't hard enough I'd ever worry about bending anything. Mine isn't bad enough to need replacement right now, but it will eventually get that way. This seems to be an ongoing issue for Onex owners, and there's more info in this older thread- viewtopic.php?f=5&t=5536

As others have done, I asked Sonex about re-bending the gear, and they said it's not recommended. They verified that the gear is still 1/2" thick, so it hasn't been strengthened since my kit was made. They didn't answer the question about the specific alloy or tempering, but in the other thread it was reported to be 2024-T351. The only recommendation from Sonex is to replace the main gear with the identical gear they sell. I'm guessing that would be around $750 with shipping.

From 100 hour of flying the plane, I'd have to say the main gear is the weakest link, though not my least favorite design decision. I really wish they'd offer a 5/8" gear, or maybe one that uses a stronger alloy, because main gear shouldn't really be a routine replacement item.

O'Keefe used to make Onex gear, even custom taller gear using 5/8" aluminum, but they appear to be retired and out of business now. It sounds like Groves isn't offering anything now, and I'd be afraid to ask the price if they did. What other option is there for a stronger, and possibly taller replacement?

Another thought is some sort of reinforcing plate that fits on top of the main gear, and extends maybe a foot or so down the legs to add support for the main bend at the fuselage. I'm not sure how well that would work, but it would be easier to fabricate than making the whole gear. Any other ideas?

[rpf]

H Rusty,

I've decided to make my own gear. I purchased a piece of 7075 flat stock (5inches wide x 5/8 inches thick and 96 inches long). I'm going to make the gear about 3 inches taller and in doing so will be slightly wider also. My friend has a hydraulic press, and we will lay it all out, cut the angles and radius all the edges before we bend.

[BRS]

H Rusty,

I've decided to make my own gear. I purchased a piece of 7075 flat stock (5inches wide x 5/8 inches thick and 96 inches long). I'm going to make the gear about 3 inches taller and in doing so will be slightly wider also. My friend has a hydraulic press, and we will lay it all out, cut the angles and radius all the edges before we bend.

I like to see some pictures on how those bends are done.
Are you going to build it so that you can use bolt-on axles? Gives you more options if you need to later add shims.

[13brv3]

H Rusty,

I've decided to make my own gear. I purchased a piece of 7075 flat stock (5inches wide x 5/8 inches thick and 96 inches long). I'm going to make the gear about 3 inches taller and in doing so will be slightly wider also. My friend has a hydraulic press, and we will lay it all out, cut the angles and radius all the edges before we bend.

That sounds like a definite improvement. Where did you get that 7075? I'm afraid to ask the price... I just got the Sonex replacement gear today. I figured with the way the industry is going, I'd better at least have a spare stock gear just in case they become unavailable like Grove and O'Keefe.

I started a thread on the homebuilt airplanes forum, and there has been a lot of discussion. I think it's safe to say the design could be improved, though I'm not sure Sonex has any motivation to make changes.
https://www.homebuiltairplanes.com/foru ... nex.48216/

[peter anson]

I've decided to make my own gear. I purchased a piece of 7075 flat stock (5inches wide x 5/8 inches thick and 96 inches long). I'm going to make the gear about 3 inches taller and in doing so will be slightly wider also. My friend has a hydraulic press, and we will lay it all out, cut the angles and radius all the edges before we bend.

I don't know how sharp the bends in the Onex gear are but the best method for making these would be to bend them with the metal in a soft condition and then have them age hardened. To do that you need to get the material solution treated - heated to about 500°C for a time and then quenched. After quenching the metal will be soft but returns to a fairly hard condition within a couple of hours at room temperature but you can delay it by keeping it cold, like packed in dry ice cold, until you are able to form it to the shape you want. The final step is age hardening, heating the formed parts to around 180°C for around 12 hours. All those temperatures and times are just guesses but the information is available in spec sheets. You should end up with parts that are high strength without inbuilt stresses. I know that may seem like a lot of trouble but I would guess that's how the original parts are made. It would probably be best to get the parts anodized too because 7075 is not corrosion resistant.

Peter

[tps8903]

I've decided to make my own gear. I purchased a piece of 7075 flat stock (5inches wide x 5/8 inches thick and 96 inches long). I'm going to make the gear about 3 inches taller and in doing so will be slightly wider also. My friend has a hydraulic press, and we will lay it all out, cut the angles and radius all the edges before we bend.

I don't know how sharp the bends in the Onex gear are but the best method for making these would be to bend them with the metal in a soft condition and then have them age hardened. To do that you need to get the material solution treated - heated to about 500°C for a time and then quenched. After quenching the metal will be soft but returns to a fairly hard condition within a couple of hours at room temperature but you can delay it by keeping it cold, like packed in dry ice cold, until you are able to form it to the shape you want. The final step is age hardening, heating the formed parts to around 180°C for around 12 hours. All those temperatures and times are just guesses but the information is available in spec sheets. You should end up with parts that are high strength without inbuilt stresses. I know that may seem like a lot of trouble but I would guess that's how the original parts are made. It would probably be best to get the parts anodized too because 7075 is not corrosion resistant.

Peter

Would it be easier to buy the bar stock annealed as 7075-0 and then bend and heat treat to T6?

[peter anson]

Would it be easier to buy the bar stock annealed as 7075-0 and then bend and heat treat to T6?

Definitely yes but I don't know what is available. My local supplier (in Melbourne, Australia) can only supply thick plate in T651. Sheet and thin plate up to 0.25" thick is available in T0. You might have more options in the US.

Peter

[Bryan Cotton]

With some proper engineering, I wonder how Ti would trade.

[LarryEWaiex121]

I can definitely see some squat in my gear I just installed 12 flight hrs ago. I can also say that I have not had any questionable "arrivals" that would explain this. The gear is just very minimal in its nature and clearly built out of a poor choice of material. This is consistent though with the Sonex "kiss" mantra.
Don't make it necessarily good but make it cheap.
Replacing gear like its a consumable isn't really very cost effective for the owner. My unit was the price of whatever Sonex was asking and $300 shipping on Old Dominion. A freaking staggering amount of money for something that had a 14lb shipping weight. Why it couldn't go FED EX Ground for a fair price I'm not certain?
Seems like everyone in the freight business agrees; if its an airplane part, that's license to steal.
I purchased my Onex as a retirement project for something I enjoy doing. It has surpassed my expectations for an enjoyable project. I did a ton more work than I expected and found a laundry list of things that clearly were not done satisfactory from day one. This little sweetie is really starting to shape up and I've just about got it to the place I can call it a "rock solid flyer".
A bit more adjusting and tinkering and I'll call it a successful rebuilding of a cute little plane.
My Waiex is getting jealous of all the attention to this Onex but its all going to work out.
Larry
Waiex 121YX, 1028 hrs
Onex 752MR, 82 hrs.