Thorp Air Command - T18.net

Can I drill a hole trough the bottom of the "socket" that you place the control stick into? I cant think of a reason why that would be a problem, but I thought I would ask anyway. I want to do this so I can run my wiring up to my grip, without drilling a hole in my control stick.

I'm getting ready to install my AP (thanks again Ira) and thought I would knock this other wiring issue out at the same time.

Well, I have not built a T-18, but I know of what you speak and I see no problem with a small hole up through the bottom - it beats a hole in the stick above the receptacle IMHO.

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Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

I haven't built one either, but i just cant imagine that would be an issue. since it will be a hole that involves the control of the plane, i thought I would lob the question out there.

That stick socket is 2024t3 billet. It is a machined part, and expensive to make, by the way. If you look at the shape of it, you will probably change your mind. That would be a long hole. When I was trying to relocate my walking beam (another long story), I did the research on how much stress the horizontal push/pull tube could be under. The answer was about 40 lbs max, as I recall. So to answer your question, structurally, you would be ok drilling that hole as long as it is centered and you have appropriate edge distance etc. Would I do that? No. First, it's a long hole to make it to the bottom. Second, once there, you are now having to deal with aileron push pull tubes and aileron stops which may cut or pinch your wires. Third, the stick is 4130 steel and much stronger. Fourth, a hole in the stick will keep the wires in the cockpit area ie closer to the AP control head, than through the bottom.
Just some thoughts
Cubes

I made my hole in the steel stick just above stick socket . Just big enough to run the wires and place some spiral wire loom on the wires as it goes thru the hole . Probably a 1/8" hole ? Maybe 3/16" ? Wires running thru the hole are 20-22 ga wires . It gets inspected every annual . Would take a pretty strong ape to bend that steel stick ! I am Serious and don't call me Shirley !

RB

Anybody using an aluminum stick? I think mine are.

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http://www.dixiefriedfabrication.com/

Yep, drilled a 3/16" just above the stick socket for trim and audio pilot switches.

My sticks are also aluminum, as called out in the drawings, but I used a little greater wall thickness. Just like Bill, I drilled a 3/16" hole just above the socket. If you take care with the hole, & de-burr & polish it to eliminate stress risers it should be fine - & especially if you use a thicker wall like I did, or maybe even make a short doubler tube to fit in that area. I'm thinking that the best location might be fore or aft on the tube, rather than on either side, as the aileron forces are generally greater than those to operate the stabilator. The difference is probably not important. Probably should use a steel stick if Patty Wagstaff is gonna' fly your airplane.

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

Now doesn't that make you feel better ?

RB

well, i guess im glad I asked, because i think im gonna go with drilling a hole in the stick now..thanks for the input.

I used an inside sleeve made of thick wall 2024 tubing turned down to fit snugly inside the aluminum stick. It runs from the stick bottom to about 3" above the top of the stick socket. Total wall thickness is about 3/16" in the sleeved area. I used a 3/16" hole about 1/2" above the top of the stick socket to run the wires through, de-burred as suggested. Have flown about 1100 hours with this and had no issues.

2024 Alum sticks, knocked a little hole in the side of the pilot stick, installed grommet, run the wires through the boot under pilot seat and used disconnects so can remove the stick. Process took 10min, I have long arms, so I shortened the sticks, made controls very sensitive, and it's easier to enter and exit the cockpit. My old 225lb 73" carcuss don't move around like it used too, so ease of entry and exit is benificial. Dan