Thorp Air Command - T18.net

Fuel tank won't fit? Yeah, I kinda had the same problem, but I can still get it in. Then with chaff strips, maybe not. Must be a not so rare problem. You know what ya gotta do. I like your welding fixture... did mine the same way and it seemed to keep things "square". Photos are good for others to see.

Les.

Well turns out no real big deal. What I did. I figured I really was talking about a 1/4 inch that needed to be adjusted to get the tank to fit. The brackets had the right profile they were just to far up (meaning to close to the top of the skin) by a 1/4 inch. So heres how I managed it. I removed the saddle formers and trimmed the bottom mounting tab off. I then made small 90 degree brackets that would rivet to them and mounted those on the cross brace. Then jigged it up with clamps to fit the tank, drilled and clecoed de-burred riveted and done in about 3 hours. I am happy.

tabs by cgifly2, on Flickr

removed by cgifly2, on Flickr

quarter inch by cgifly2, on Flickr

new fit 1 by cgifly2, on Flickr

jigged by cgifly2, on Flickr

fitted by cgifly2, on Flickr

finished by cgifly2, on Flickr

Sure is nice to have the skins off to get in there and see how things fit. My project came with a partially completed fus. so I spent a lot of time on my head and back trying to get a good look at things to get the tank to fit correctly (probably got it 95% correct ?) If I were building up the fus. I sure would leave off the top cowl skin off until the tank had been fitted ! Good job Mr. skeet !

RB

Thanks and I wish anyone else would jump in here with "if I were you now I would" :^)

Don't forget you need to put the cork and or rubber chafe strips in the "craddle." Same sort of procedure as fitting the canopy and windscreen/trim strips. If you fit the glass without the rubber strip and drill the mounting holes and then try and fit the glass over the rubber, it won't line up correctly. As Agent 86 would say..."Missed it by that much !" Otherwise..."Looking good Billy Ray !"

May not seem like much, but that little bit of chafe strip can throw off the whole fit of the tank !

RB

My 2 cents: install a positive locking cap, weld in a 3/8 or 1/2 npt boss on the bottom (not 1/4 npt), plan for a flared vent tube so you don't have to put hose on it. Plan your wiring conduit... I don't agree with having wire laying across the top of a fuel tank.

Consider welding in a reinforcement patch around the outlet boss so you CAN hang the valve directly off the bottom without losing sleep over it. This is by far the simplest way to plumb the valve. (Most of the T18's I looked at at KD2011 had the S/O valve on the tank, and we don't hear anything about tank cracks anymore.)

Best way to mount that shut off is on the tunnel or tank support with a remote rod or cable as the control if necessary. I'm not going to doubt you Dick but I can think of at least 7 of the (?) thorps at ky dam last year that do not have the primary shutoff mounted to the tank. That being said I, Wendell and I'm sure many others have a shutoff mounted to the tank but thats simply to allow servicing of the fuel lines/system. The point is the one mounted to the tank is intended to be used infrequently. The cracking fuel tank is no myth, I would not risk it.

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD

Great stuff, this is what I want to hear. 7077J had the shut off valve on the tunnel with in arms reach. The line went from the tank towards the cockpit through a electric (free flow when off) fuel pump to the S/O then back to the engine compartment. I am absolutely removing the fuel pump and will consider options regarding placement of the S/O valve. I am not one to turn it off after every flight. But of course will want it easily assessable in a emergency. While we are on the tank. The original fuel gauge was a float and arm type. It worked just fine, but was mounted in the middle of the tank towards the cockpit. I kinda like the top mounted ones, but am scared to mount it under the skin. Will not put an extra access panel on top skin, so reliability is a paramount quality. Any Ideas? I am not completely ruling out the same float and arm gauge, but just thinking out loud.

Put that access panel on top and don't sweat it! None of them are 100% reliable.

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD

No worries, Lee-man, I am planning to attach my SOV remotely. Details to follow. I was just saying.. hanging it off the tank sure makes it easy. If one were to build for that by strengthening the boss area, it might be worth it. But regardless, it is IMPARITIVE to have a flex line somewhere in the system in case of an "incident."

Speaking of senders, I have a float type, probably SW, and I had to take mine apart to get it out! The part with the resistive wire, and the wiper, inside wouldn't quite go through the boss on the tank. I had to take the business end out through the bung. Something to watch for if you are building a new tank.

I was talking to somebody out there about installing a capacitive sender... can't remember who. Keith Sneider? Paul Gagnon? Any news?

Y'all have a good time at SnF! Wish I could be there. Saving my jeeters (Fraser) and holidays for Texas.

Skeetman ! Put that access panel over the sender ! You will kiss my feet when the thing goes FUBAR and needs to be replaced. You will not enjoy removing the tank to do that. I put my access panel in and took about 2 hours ? Already had to remove it to do the final cal on the fuel gauge. I have the bendable probe. No float. So far works like a champ !

RB