I put a hatch above where the fuel tank would be. Ideally the battery would have been placed against the firewall but because I was nose heavy there is battery box built under the canopy that the battery slides into. The plywood block with the phillips head screw is used to hold the battery back in the box. The hatch is held on with wires in the front and a magnet at the rear. Cutting the hatch was easy because the top of the fuselage was carved from a large piece of 1 inch thick balsa that was hollowed out on the underside.