Check the Japanese Nakajima J1N1-S Gekko upward cannons....Interesting...Who was first, Schräge Musik, I guess?!
Interesting, more info:
In the spring of 1943 , Commander Yasuna Kozono of the 251st Kokutai based at Rabaul suggested that the J1N1-C might make a good night fighter that would be effective against the long-ranging nocturnal B-24 Liberators that were constantly raiding Japanese installations in the East Indies. Ground crews at Rabaul removed all the equipment from the observer's cockpit and faired over most of the transparency that covered his position. In place of the observer, they mounted two fixed 20-mm cannon firing obliquely upward at an angle of 30 degrees above the forward direction. Two similar cannon were installed in the ventral fuselage behind the wing firing 30 degrees downward. The observer was no longer needed, since his position was now occupied with guns, so the crew was reduced to two. The modified aircraft was designated J1N1-C KAI.
http://www.csd.uwo.ca/~pettypi/elevo...her/j1n1s.html
[ 16. February 2004, 09:40 AM: Message edited by: Kai-Petri ]