Thorp Air Command - T18.net

Does anybody have any how-to experience to share with "turning down" the 2" x 0.12 35" 2024 T3 aluminum tube small enough to be inserted into the 2" x .049 main spar tube?
Thank you

Hi!
For my opinion the stabilizer "spar" and the entire stab assembly was the biggest challenge.
I'm turning around during 3 months to find the way and to find the "tubing material" to do the job.
Finally, I order the tube from Eklund Engineering! Expensive, but the quality was perfect.
It's the only part I buy since I start rebuilding my plane.
I hope you have a big lathe!!!

Good luck!

_________________
Thierry
French Canadian T-18
C-FPVE #091

A big issue. I've asked for relief of this design from an engineer. Tough to make.
Cubes

After the 300 mph tail failure, John Thorp put a lot of money and effort into vibration analysis for this spar mod. It works with the weight distribution of the bob weights on the stab ends and control arm. Lore has it that the horizontal is now "supersonic". Of course, it has not been tested to that limit. All that said, I would not mess with the design, without doing equal or better live testing on an alternative one.

_________________
Bob Highley
N711SH
SN 835
KLAL

In talking with Cubes, the issue is that items that were common when John Thorp designed the T-18 are in many cases not being manufactured today. As such- to make future airframes 'fly' it will be necessary to find an alternate means to fabricate parts. The other item that Cubes and I talked about was the extrusion to make the 577 lower rudder attach fitting. Again, that size - not available. It's one thing to have the Thorp parts business, but now to have to 're engineer' and 'test' parts is a whole different animal. Thanks to Cubes for stepping in and making the huge effort to get more airframes into the air.

Oh, and I heard that Spanky has volunteered to continue the stab testing program when the time comes.....

I probably have the stock to make the 577 fitting

If anyone needs the hor. spar tube and doubler , check with John Kerr I believe still has at least one of each and he can tell you how he got the doubler into the main spar tube .

Can't remember installing my spar tube reinforcement - it's been quite a while ago now. I can say you don't want a loose fit, but with small clearance I recommend being real careful not to get it stuck only part way in. Aluminum will gall up real easy and can almost "weld" itself together. Be sure parts are wiped down and very clean from grit, etc. Add a little dry lube or something too. To buck the rivets I used a heavy round bar with a flat ground all along the side. Suspended it with the stabilator between two saw horses.

Les Krumel,
Albuquerque