| Maybe someone can assist me with my failing memory, but I recall reading about a Japenese fighter that had a pair of "upward" firing cannons located behind the cockpit. The idea was to fly beneath the B-29s without having to confront the main armament of the bomber. |
Three that I can find are the Ki 45 Toryu , Ki. 46 III KAI Dinah and the JiN1-S Gekko.