largest prop diameter for Onex?

[13brv3]

Great info Wes! Was the other landing gear something you bought off the shelf, or did you have it made? Looks like a great solution for longer props.

[WesRagle]

Hi Rusty,

Was the other landing gear something you bought off the shelf, or did you have it made?

Yes :-)

I don't remember the exact chain of events, but while searching for a taller gear Todd Reifers (AKA wolfpack3) contacted me and suggested the gear that I ended up buying. The gear was fabricated by O'Keefe Aero. The gear was designed by the late Steve Bennett of Great Plains Aircraft fame. When Steve and Linda decided to sell the engine operation they retained parts of the business including the landing gear segment. The portion of the company they retained is now O'Keefe Aero.

Linda doesn't design landing gear and so only sells gear that was designed by Steve.

As far as I know Todd is the only person who has flown the gear. He said he liked (the airplane has been sold) it a lot. His motivation for changing gear was a desire to use a different tail wheel configuration.

Todd's a big guy. Todd said the gear splayed out bit too much when the plane was fully loaded so he had to add washers to the axle mount. Todd suggested the 50 Deg. bend be increased to 53 Deg. Linda was happy to accommodate that small design change. I had her increase it to 51 Deg. I don't know yet but it might have been better to follow Todd's suggestion.

As I'm sure you know, one change leads to another which leads to another ...

By the time I made the adjustments necessary to bring the airplane back to the proper attitude the supplied tail wheel push rod weldment was no longer usable.



Me, I worry about everything so I worry about the additional aft bending moment when the gear makes contact.

Anyway, like I said, I can't recommend the set up because I have no operational experience with it. It's a mod I decided to make and good, bad, or indifferent I'll take responsibility for it.

Wes

[13brv3]

Thanks again for the excellent info Wes. The project I'm getting is sort of a replacement for one that I (foolishly) sold a couple years ago. It might be a couple weeks before I get it back home, and I'll take a more serious look at the situation then. I found the O'Keefe Aero site, and will follow up with them as needed.

From the pictures you've shown, it looks like the spinner measurement would be 33-3/4" with the shorter gear. If you allow 6" for clearance, it leaves you with a 55.5" prop. Of course none of that accounts for how much the gear will sag at gross weight. Looks like they made the gear about as short as they could for the normal 54" prop.

I guess the next question will be to figure out just how short an 80 HP 912 prop can be with a 2.27 ratio drive. Plenty of time to ponder this, particularly if it keeps raining every day and keeping me from hauling the new project home.

Thanks,
Rusty

[WesRagle]

Hi Rusty,

You're welcome.

And don't forget that my measurement I made was with the tires fully inflated.

One thing that has been my life long nemesis is paperwork. At present I've been relegated to paperwork hell. So, just a heads up in case you're not thinking about it... Be sure you get a Bill of Sale from all previous owners of the project before walking away with your new toy. Also, as it turns out, if any of the previous owners are deceased, the bill of sale can't be signed by their surviving spouse. You will need a notarized "AFFIDAVIT OF HEIR-AT-LAW" from the surviving spouse before the aircraft can be registered.

It's all great fun :-(

Best of Luck,

Wes

[13brv3]

Thanks for the warning. No major complications here. The current owner was the original kit buyer, and he's not dead. Hopefully I'll get to pick it up before either of us gets much older :-) Getting the kit bill of sale squared away is the first priority, along with securing any pics and documentation he has.
Rusty

[WesRagle]

Getting the kit bill of sale squared away is the first priority

Not to be a nag, but just to be clear, *both* bills of sale. The one from Sonex to him and the one from him to you. You'll need them both to register the aircraft.

Wes

[tom0nex74]

I have the standard Sensenich 54X44 prop on 0nex 74. It measures 40 inches from the tip of the spinner to the ground and 12&3/4 inches from the tip of the blade to the ground in the tailwheel position. 34 inches from the spinner and 6&5/8 inches from the blade tip at level position. I fly it off and 3 point land regularly with no problems. I looked into a Rotax with one of the Duc props but could not find anything suitable for a reasonable price. I think there might be one out there somewhere. good luck.........................Tom Ryan. 0nex 74

[13brv3]

Thanks for the measurements Tom! It's good to have another data point, and it matches pretty closely with the data Wes provided. It really sounds like 54" is the largest prop you can expect to run on the stock gear.
Rusty

[13brv3]

OK, so I have the Onex project home, and I'm getting serious about working on it. I spoke with O'Keefe about the taller gear, and they're 2-3 months out. I also worry that maybe I couldn't get a replacement get in the future if it was ever needed, so I'm still trying to figure out a way to use the stock gear, with maybe a 60" prop for the 912UL.

I've seen comments about taller tires, and it would be hard to find tires that aren't taller than the little Chen Shin 11x4.00-5 that's on it. I've seen a number of comments about 5.00x5 tires being taller, but I can't find any measurement for how much taller.

Does anyone know how much extra clearance would be gained with taller tires, even if it requires larger wheels and wheel pants? Naturally we're not talking about big bush balloon tires here.

Thanks,
Rusty

[13brv3]

OK, talking to myself here :-)

I found some dimensions on Goodyear's site, which show a 5.00-5 tire to have a diameter of 13.7"-14.2". The stock tires are 11", so that should give about 1.5" extra ground clearance. If the stock prop is 54", that brings us up to 57" with the same clearance. I've been talking to Hoverhawk about Bolly props, which look like a pretty nice option. They tell me that a 58"-60" 4-blade prop will work well with 80HP, so I think that will likely allow me to use the stock gear, with 5.00-5 tires. I'm sure you lose some efficiency with that many blades, but it will make up for it in coolness :-)