Two airmen of the 306th Bomb Group check a Sperry Computing Gunsight underneath a B-17 Flying Fortress. Image stamped on reverse: 'Sport and General.' [stamp]. 'Passed for Publication 9 Jul 1943.' [stamp] and '273716.' [Censor no.] Printed caption on reverse: 'THE DEFENSIVE POWER OF FLYING FORTRESSES. The extremely heavy defense of the Flying Fortresses has enabled them to fight their way through to targets like Huls and Kiel in the face of the most intensive fighter opposition aerial warfare has ever seen. The result of these and other encounters has been the destruction of more than 1100 enemy aircraft. Formations pf Flying Fortresses have an average of 12 1/2.50 calibre machine guns per plane (which can be manned simultaneously by the usual crew of ten). 27047 An acurate gun sighting instrument . The Sperry computing sight. This instrument gets a bulls eye every time. S. & G. G.C.'