The most important thing you can do for the firewall is epoxy down the fuel hatch cover. Don’t screw it down. Even better, replace the balsa cover with glued down aircraft plywood. Remove the covering material in the glued area on all 4 edges for 100% contact. This forms a very strong box structure VS a channel. . Its funny how may people want easy accesses to the tank and ignore the instructions, I can’t blame them.


The second reason that the firewalls fail is that some guys spin up the starter, than slam it into the spinner nut sometimes misaligned, shaking the heck out of the poor plane.
Back the prop off compression so you get some momentum, line up the starter on the spinner and push the switch....much less violent.


Pictured, is a new in-box fuselage with the tail pre-broken. I removed the covering around the area applied medium CA in the crack and held it closed than carbon fiber strips were added high on each side and one on the bottom.