I built a really nice tail dragger and and instead of putting the fuselage doublers on correctly, I installed them so that I had left thrust on the firewall. I took it a step further and never caught it until I installed the engine and it was pointing the wrong way. You should see the shims I had to build to fix that screw up. There would also be the L-19 that I scratch built. I installed my fuel tank in the front and installed my battery under the fuel tank. I added all my foam to make sure that I had no fuel foaming issue's and then I installed all the top sheeting. Then the big opp's jumped out. I had drilled the fire wall for the pushrod, but not for the fuel tank. No problem, I will pull the tank out from inside the plane. If only I had made the bulkhead cutout a 1/4 inch bigger that tank would have come right out of there. I got to scratch build all that front end sheeting again. I need the practice I suppose. Good Luck, Dave