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Fuse Center section

tjo

Well Known Member
In the instructions it says to bolt together the fwd and aft center sections with 1.438? blocks to test fit, then take the apart. Seems kind of a waste to fabricate wood blocks to this specific dimension just to put them together and take them apart. Is this really important? Is it really necessary? What is the goal? I appreciate any input.

Tim
 
You need the spacers to ensure that your wing will fit nicely into the fuselage later. I borrowed some from a seven builder. They had dried a bit and the wings are very tight fit. Better yet is to make spacers out of aluminium that will remain stable. They are required.

Jack
 
Buller

Buller makes spacers. He can make standard dimension or custom to the dimension of your wing spars. I used 1.444". .005" thicker than the spars. My wings slide in with just the right amount of effort. I left them in place till the fuse was riveted together.
 
Yep, you need the spacers. I made some out of aluminum for better dimensional tolerances. Find a buddy with a CNC and bribe him with a six-pack.
 
I borrowed spacers from another 7 builder. They were pieces of laminated wood milled to the corrrect thickness. I added a layer of blue painter?s tape to each side to ensure I wouldn?t have a problem fitting the wings. I?m glad I did, as I measured the spacing just before fitting the wings and came up with a 10-15 mil interference fit. (I think I tightened the temporary bolts a bit too much and compressed the spacers slightly). Surprisingly enough, after chamfering the inboard edges of the spars and greasing the spars and center section, there was enough give in center section that the wings slid in with a minimum of effort.

http://www.mykitlog.com/users/displ...r&project=2052&category=7733&log=251539&row=9
 
I took some good old 1/2" electrical conduit tubing, cut it with a tubing cutter, then worked it down to the correct length on the grinder. Check the length with some calipers and stick them down between the front and rear sections and bolt them in place.

Since everything is prepunched, it is probably overkill, but at least you'll know that the wing spar will fit in there nice and tight.
 
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