jjglennon

jjglennon

Member
Hi All,
Can anyone shed light on the correct positioning of T-405, the Tank/Fuselage Attach Angle, as it is to be positioned on the inboard tank rib? The piece appears on sheets 18a and 21, but I find no dimensions or angles associated with it, except that it appears to be parallel to the bead on the tank rib. Please point me in the correct direction.
Thanks in advance.
John
 
Check out dwg 18 closer

Its made from a piece of 3/16 angle 2 inches from front to back and starting with 2 1/2 sticking out towards fuselage. That 2 1/2 side gets a symmetrical bell shape. The top to bottom length conforms to the shape of the forward end of that tank rib. Make a heavy paper template and then trace it onto the 2 inch side of the angle. That should end up being about 4 inches long. Cut it and work it on your belt sander to near final shape. Remember to make the mating doubler that goes inside the tank opposite this T405 angle (T-410) out of 063 alum plate. Dwg 18 shows that measurement to be 2.205 inches front to back and 4.045 inches top to bottom. It also gets shaped to match the inside of the tank. It's dimensions are a little larger because there's no rib flange to take into account inside of the tank like there is on the outside. They all get riveted together along with plenty of proseal. Also, take a minute and think about where to locate the rivet holes in these so they don't interfere with riveting the tank skin to the rib. It's real close in there and you might need to scallop the bracket edge to get clearance where a shop head from the tank skin will be. If your skin has not been drilled to the rib yet, locate those forward rivet holes a little closer to the edge (maintain proper edge distance) of the rib flange to allow that 3/16 thick angle to have minimal interference.
 
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Thank you for the thorough reply and your good advice. My question relates to the placement of T 405 on the rib...

If I were to lay the inboard tank rib on my workbench and look at T 405 from above, T 405 would look like the letter "D". The "D" can rotate clockwise or CCW a few degrees with the given dimensions of T 405. Does the straight side of the "D" follow a line parallel to the trailing edge of the rib or parallel to the bead on the rib?

The crux of the question is: What measurement insures that the builder has properly aligned the straight side of the "D"? Or is it possible that TLAR is OK for this piece because the fuselage piece to which it mates is fitted to T405, no matter it's angle, during the fuselage build?

Thanks again. Sorry if I'm just being dense.
John
 
Mine are parallel to the strengthening bead..

pressed into the rib immediately below the location where you would mount this piece. You are correct in that you will mate the two together when placing the fuselage bracket in the correct location later on so it's all good. I suppose if you still have the two tooling holes avaliable in the rib and positioned the bracket at 90 degrees to a line drawn through those holes, you would be spot on.
 
WenEng said:
...Also, take a minute and think about where to locate the rivet holes in these so they don't interfere with riveting the tank skin to the rib. It's real close in there and you might need to scallop the bracket edge to get clearance where a shop head from the tank skin will be. If your skin has not been drilled to the rib yet, locate those forward rivet holes a little closer to the edge (maintain proper edge distance) of the rib flange to allow that 3/16 thick angle to have minimal interference.
Click to expand...

I'm not sure what the -6 instructions say, but those very same parts on -7 tanks are recommended in the instructions to be riveted after the rib is riveted to avoid problems with setting the skin to rib rivets.
 
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