This is a roddy good section, with plenty of good acting as they say in Python. Actually, this is better suited to Princeton basketball, because there are tons of layups to be done. The first is to bid the top and bottom of the spar to the firewall, and the little chamfered openings on the back of the firewall. Of course the usual rules apply, scuff up target areas first, the glass bubbles to create a radius, apply the cloth, then peel ply. Since there are 2-47″ bid on top, 2-41″ bid on bottom, and 2-9″ bid on both sides of the back (and, oh did I mention, BID is cut at a 45 degree angle on the cloth following the thread line…) this is a tedious and time sucking task. Easy, yet laborious, just the sort of thing I’m really good at. {wink} The best thing I can say about this evening’s work is “it’s done”.

Spar Bonding – Fore Firewall

Spar Bond – Rear Firewall

After these initial layu

ps, the work moves on in earnest. Next we made two foam pieces for each side of the spar out of 3/8″ foam, one to go on top of the gear bulkhead (6″x4 1/2″) and one to mate the gear bulkhead to the top of the spar (6″x10 1/2″). Once they were approximately sized, we cut the top of the gear bulkhead to the same height as the bottom of the spar so the foam laid in there nicely, and then beveled the edges of the diagonal sheet to rest well in it’s position. Then I covered the foam with micro (a step not mentioned in the manual, but always a good idea) and bonded them into place with micro (the manual says to duct tape them into place, but the tape wouldn’t stick worth a d@mn for me, so I went this route instead). Then all of the mating surfaces were well scuffed and they layups began (on plastic first, since there were many to do, and most of them were triaxial cloth). Here’s what they look like.

Spar Foam Reinforcements

Spar Layups on Plastic


First we laid 4 plies of 6″x8″ BID inside of the support from the top of the lower spar to the bottom of the upper spar.

Spar Foam Inner Layups


Then we laid the sets of TRIAX on the top of the support. First was 2 layers of 7″x8″ from the firewall to the top of the spar, then 2 layers of 7″x25″ overlapping the first up to about 6″ above the spar and running just onto the gear bulkhead by about 2″, the 2 layers of 7″x33″ overlapping the second and running all the way down the gear bulhead and over the main gear bolt holes. Then 1 ply of TRIAX (4″x12″) was run down from the bolt hole to on top of the floor duct, and another 1 ply (also 4″x12″) of Triax was run from the bolt hole diagonally lapping onto the fuselage side.

Spar Foam Outer Layups

Finally, a 2″ wide piece of BID was laid up onto each of the fuselage-to-spar inside and out over a radius of micro.



Posted By: Brett Ferrell
Wednesday July 31st, 2002 at 5:59 PM

Categories: Main Spar
Tags: Building Fuselage Spar

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