Interesting photo Rich. Have not seen one like that before, pitty the area is a bit fuzzy. But there is definately something there. Getting back the the drawings Mike posted. The large half moon opening is indeed for cooling, but never had a cover over it on any SE5 variant. The half moon panel A10799 is the end cap of the fuel tank. The small rectangular opening is the spent cartridge case schute from the vickers, and the square-ish hinged flap/hatch is access to the fuel tank drain valve. Regards, Pete in RI