Thorp Air Command - T18.net

Hi Guys,

My Thorp project is progressing slowly, but at least it is progressing.

My tailwheel is rather worn, and I was hoping for recommendations on the best tailwheel for the Thorp. I will be landing on both grass and asphalt runways.

Any advice is appreciated!

Thanks,

Marc

Aviation Products double fork six inch on a 5/8” tapered rod spring.
Cubes

Thanks Cubes! Much appreciated

I'll second what Cubes said.

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Bruce Finney
N18JF T-18C #262
Yelm, WA USA

If you use the Aviation Products wheel the first thing you do is shit can the standard wheel bearings that come with the wheel and get a Timken set of quality bearings or their equivalent .

RB
NX115RX

I third what Cubes recommends. I swapped my wheel out for a pneumatic one.

Jim

How is the tapered rod attached to the aircraft? I need to replace my Maule tailwheel as well.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

Here's a photo of the old spring and Maule tailwheel as it came off of my aircraft, calling it a "spring" is being kind.


Here's the new Trusty spring and AViation Product double fork 6" tailwheel. Note the bolster at the front end of the spring, this should be the same as called out on drawing A-862. No mods were made to the aircraft. Since my aircraft did not have the bolster, Tom Hunter made me a deal and included a bolster with the tailwheel and spring


Hope that clears things up, clear as mud eh!

Note on Rich's comment on bearings, I've had my tailwheel on the aircraft since Dec 2008 and have not had to change bearings. That said I read some time ago that an airplane pieces part vendor was sourcing the tailwheels without bearing and installing el-cheepo bearings. Also stated that the wheels that came straight from Aviation Products were quality bearings. I don't remember the source of this statement so it's worth what you paid for it.

Disclaimer - your mileage may vary.

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Bruce Finney
N18JF T-18C #262
Yelm, WA USA

That’s exactly my tailwheel. I don’t see, however, how your new tailwheel has the three attach points like the Maule tailwheel had. Is that what the “bolster” is? I’m not familiar with that term.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

Hey John, the parts that Cubes will sell you include everything you’ll need to bolt the new spring to the aircraft.
The advantage you will find is that the new tail spring drops the tail of the airplane an inch. Allowing for a better 3 point landing attitude. That and it’s not as stiff as the original half trailer spring style. And then there’s the “less drag” , goes faster discussion….
You will find it’s a definite upgrade!
T

It also moves the tail wheel 9” aft, which helps a little with over correcting.
John, the front end of the spring has a hole that the AN6 bolt goes through. There is a small washer to keep the spring parallel to the belly skin. As you move aft, there is a collar that slides on the spring. The collar has two ears that the AN4 bolts go through. You also have to drill a 5/16” hole laterally to install an AN5 bolt (not on your Maule spring) that keeps everything from rotating.
Cubes

John, look under your plane at the aft spring. There is a 1/4” aluminum plate that the spring bolts go through. That is the bolster. Every plane should have one. If you don’t, I have them.
Cubes

Owners should look at that bolster plate once in a while. On my last T18 it was quite badly corroded between the plate and the skin.

D

Thanks, guys! I was concerned that I’d have to make changes to the fuselage structure.
Let’s talk when you have a moment, Cubes, to hook me up.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

Dick Wolff…I agree. I pulled mine off because I could see a little white powder at one edge of the bolster plate where it touched the fuselage skin. When I took it off, there was definitely significant corrosion on the bolster plate itself with some pitting. Luckily the skin of the fuselage wasn’t corroded. I painted the bolster itself after sanding smooth, flipped it over for good measure before reassembling. My point is you’re right. It wasn’t easy to see what was going on. I’ve thought about maybe cutting a thin nylon spacer to separate the two and hopefully eliminate electrolysis. Any thoughts?