Thorp Air Command - T18.net

I have been working on the 4130 1/4 and 3/8" main beam brackets and am expecting to perform the reaming to fit steps following the HT to 150,000 psi. I believe that I will be able to machine following the heat treatment. What do you think, am I on the right plot?

Thanks
Tom

I made my own, as well. The fittings are machinable after heat treat with good quality tooling. Make sure your plating guy is aware of and able to meet aircraft specs on the cad job.

_________________
Bob Highley
N711SH
SN 835
KLAL

Bob, Les and I made our fittings together on a homemade wooden bandsaw. We drilled all the holes #30 and had them heat treated. Fitted them to the spars and used a drill press, clamping the spar, drilled the holes to proper size. Upon mating the outer spar with the inboard spar, I pinned the fittings with a 1/8 rod. I also made up a 7 degree angle using angle iron and clamped the spars then drilled and reamed the 9/16 holes. This way you have the same angle on both wings. I do believe that a heavy drill press is manatory to prevent wobble when drilling/reaming. A hand drill will not get it, a give you a loose pin and a lot of wing movement.

I got mine from CSA . Heat treated , matched hole drilled . Perfect fit !

RB BOOM !

Great,
Thanks for the comments and suggestions.

Tom

Gentlemen,
When I take my c wing brackets to the heat treatment shop and I say heat treat to 150,000 psi., I bet there will be follow up questions.

Any words of wisdom on what the right answers will be? Mil specs? etc

Tom

I would take a copy of the plans that states the psi requirement so there is no confusion .

RB

Sounds like a plan. Thanks Rich

When I read this post, I feel pain in my stomac...
Steel plate, heat treatment, wings attatch....
After a deep research I found this steel plate is for the C wing only!
Now I feel better with my T-18 standard wings

(tittle said C wing brackets) Next time I read all the text before pressing the panic button.

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

Hey guys,

I'm at the point of making .563" dia. pins for the C-wing brackets (spar fittings). I have the same idea of making them about .030" oversize and turning them down to fit after heat-treatment. I reamed the holes in the fittings first with a standard reamer, thinkng I had better control match the pins to the holes, instead of vice-versa. I'm hoping it cuts well with sharp lathe tools; I have no grinding apparatus. This is one place to have absolutely a zero-slop fit.

Although some of the parts are different than the standard wing, the concept is the same. I didn't think I could just buy them since jsut half a mil could make a difference. Any comments on you dealt with it and your results?

Looking forward to the "50th Land of Enchantment" fly-in, here at Double Eagle this weekend. Sure wanted to make it to the Thorp fly-ins. I'm still on the ground, but I'm just that close to gettin it done.

Les Krumel,
Albuquerque

Calm down and go have a Moose Head !

RB

Les: I got my wing fittings and pins from CSA . The pins were "slightly" oversized . I just "polished" them on a 3M wheel and that was enough for a "snug" fit and no slop...I should say NO PLAY ! It still takes a few good pulls on the pin removal tool to get them out .

RB

The three amigos all made their steel fittings for our wings. We bought our pins from Phil Tucker.
I drilled the fittings for a 1/2" dowel pin prior to heat treat. After heat treat I mated the fittings drill and reamed them using a large floor drill press very similar to a mill. Both Bob and I now use bolts in the wing for no other reason than we don't fold our wings, Les used pins and had a small amount of play. I think it is important to use a heavy mill and clamp the fittings to eliminate any "wobble" which will result in a loose fit