Thorp Air Command - T18.net

Assuming you have the pre-fab box (with pre-drilled holes), use it as a template on the inside of the firewall for your location. Assuming you are going to use nut plates (cockpit side of the firewall) to attach the battery box to the firewall ? I belive I did a NL write up on the install of my battery complete with parts list ? [:0]

RB

Thats my problem. Since the fuel tank is already in place, I cant get to the cockpit side of the firewall. The only part of the firewall that is accessible from both sides is very the lower portion of the firewall behind the rudder pedals and there is already stuff hanging on the firewall all over the place down that low. The only place I can fit the battery box is where you have yours Rich. But again, I cant access the inside of the firewall that high up because the fuel tank is there. Im not in the frame of mind at this point to take out the fuel tank to hang the battery box so I may be at a dead end.

Its just if Im gonna move it, I want to get the most benefit I can out of it. And moving it to the firewall will help me CG the most.

I thought that might be your problem. It may be possible to rivet (Cherry Max Structrual Rivets) a stand off bracket, with nutplates to the engine side of the firewall. It's been a while since I looked in that space in the cockpit to see what the clearance is, but I believe where I put my attach points, clearance was not a problem. The tank does not sit flush with the firewall as it sits in a cradle. In any case you will have to verify that no wires or lines will be drilled into. A drill stop on the bit will also prevent "over drilling." That would prevent drilling into the tank.Any ostacles such as wires, etc. will require a look see. [;)] You could also slip a strip of aluum. or thin plywood (or?) in between the cockpit side of the firewall and any obstructions that you may have a concern about before you drill. [:p]

RB

I believe the saddle the tank sets in positions the tank about 3/4" from the firewall. You can use a drill stop or slide a piece of tubing over the bit and leave just enough sticking out to drill thru the firewall thickness. I would put a re-enforcement plate on the outside and pick up the outer firewall corner rivets and the fueltank saddle rivets using cherrymax or equiv. You can buy blind nuts (hardware store)and install them from the engine side and use them to mount the battery box. I mounted a remote oil filter this way with the exception used countersunk 10/32 coming thru the re-enforcement.

Yep...on the stiffener plate. Put mine on the inside. Outside works too. Auto speed nuts would work.

RB

Bill, would you mind sending a picture of your attachment setup you describe above? I think I understand what you guys are telling me but a picture is worth a thousand words. Many thanks for all the input.

Go to my photo album, click image "Thorp-oil cooler 005jpg. Double click on it and it will give you an exploded view. This is how I mounted my oil filter, a simular setup could be used for the battery.

thank you very much.

Here is a picture of my battery mounted on the firewall. It is an Odessey 625, with a homemade aluminum (riveted together) mount. Two 1/4" bolts hold the battery in place in the mount, and 4 flathead #10 bolts with countersunk washers hold the mount to the firewall--but I had nutplates on the back side of the firewall to bolt to.

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Dave M
Sacramento
ex-T-18 owner