RE: Sig Hog-Bipe kit.
Here are some pictures of the hatch. On the fuse, I added a couple sister balsa sticks on the outside of the most outside balsa sicks forming the deck. These were spaced one push-pin width away from the existing balsa sticks. For the hatch, I cut out some additional formers and glued them in one push-pin width away from the fuse formers. I also glued the balsa sticks to the fuse formers butting up against the hatch formers. Then I sheeted the entire top, and after the glue was dried i carefull probed the area until I felt where the corners of the balsa sticks and hatch former were. Then after they were marked, I inserted the razor knife starting at the corner marks and carefully slidding it to the middle. The two balsa sticks helped guide the knife and made it fairly easy to cut. Then with a little pursuasion, the hatch popped out. There is some patching that needs to be done to clean it up, but all-in-all, I am happy with it.
I just have to decide on how I want to fix the hatch in place. I don't really want any holes in the firewall where oil or fuel can get in, so I don't like the piano wire idea, but I don't really want any latches on the top, so I don't like the jet hatch method either. I am trying to think a way to run the wire from the open cockpit up to the hatch and have the removal method in the cockpit some how.
Right now, with a 16 oz tank and 1/4" foam the tank is nearly hitting the hatch, so a smaller tank might still be in order. The floor is in the perfect location height wise for the carb alignment with 1/4" foam.