I have a 40 size trainer that seems to want to pop the firewall. I have repaired this problem three times using 30 min epoxy once and then Gap Filler CA. The plane is a Thunder Tiger Trainer. Might not be the best trainer out there but it does fly nice for me when I can keep the firewall inside the fuse. Is there a method of boxing in a frame or some other building/repair tactic I can use. I do need some help with this. Thank you

Bluesun9

Glass cloth works great. If the firewall is pulling loose from the fuselage sides, glass works wonders.

Any glue you use needs to have a chance to get into the wood. It's gotta be able to get to the wood to penetrate it. Fast epoxies don't penetrate worth spit. Use 30 minute at least.

Adding fiberglass cloth would work well as Da Rock mentions above. The problem is most likely that there is probably not enough gluing surface to make a strong enough joint of the firewall the sides of the fuselage.

Adding triangular stock to the inside of the fuselage before re-gluing should solve the problem as well. Be sure to clean the area well of old glue before adding the tri-stock and attaching the firewall. Slow set adhesive will certainly provide a stronger joint as glue has more time to penetrate the substrate. Applying adhesive to both sides of the glue joint is also a good idea to insure that you don't endup with voids in your glue joints.

Another method you can use to help add strength to the firewall is to "pin" the firewall in place. It's a pretty easy procedure and adds a lot of extra "holding power" to the firewall/fuselage joint. Once you have the firewall glued in place on the plane use pegs made from wooden dowel rod to secure the firewall. Simply drill through the fuselage into the firewall on both sides of the fuselage, usually 2-4 pins on each side depending on the plane size. Now use epoxy to glue the dowel rod into each hole and then simply cut off the dowel rod flush with the fuselage.

Ken

The firewall on my Alpha 60 separated 5 minutes into it's maiden flight. Horizon replaced it after seeing pictures. There is not enough room for triangle stock on the sides, due to the engine mount, so I used dowel and pinned it as you talk about above. Quick and easy to do and I've had no problems with it.