There had been interest in the idea of a prone pilot for combat aircraft to reduce the effect of g-forces during maneuvering. Several aircraft had already experimented with this layout for various reasons, the Horten IIIf had a prone pilot, but this was primarily to reduce drag in this high-performance glider, while the DFS 228reconnaissance glider also used a prone pilot to make it easier to seal its pressurized cabin. It was not until the Berlin B9 was built specifically to test this arrangement for improved g-load that any serious effort toward development could be carried out. Starting in early 1943, the Berlin B9 twin-piston engined experimental aircraft demonstrated that it was indeed possible for a pilot to fly the aircraft lying down, and that it did improve his ability to handle high loads. The pilot had an extremely restricted field of view upward or to the rear that made it suitable only for certain roles, including bombers or fighters or interceptors with a major speed advantage over their opposition. Based on this research, several late-war German designs followed the B9's lead and used a prone pilot. Better g-load performance was not the only reason, however, as this layout also reduced the frontal area of the aircraft. This was a serious concern for interceptors attacking the USAAF's B-17 Flying Fortress, as calculations showed that the chance of being hit by its defensive guns was largely a function of frontal area. The genesis for the Hs 132 was an 18 February 1943 specification published by the German Air Ministry calling for a single-seat shipping attack aircraft to counter an expected invasion of Europe. A piston-engined aircraft was called for at the time, but the performance requirements led to a switch to jet power. Henschel submitted their design for RLM approval in April/May 1944, by which point they had already started wind tunnel testing the basic layout. The aircraft that emerged had a roughly cigar-shaped fuselage with short-span mid-set wings and a horizontal stabilizer with considerable dihedral ending in twin rounded-front vertical stabilizers. The BMW 003 engine was mounted on the back of the aircraft above the wing, likely to make servicing easier due to the low ground height of the aircraft that put the engine roughly shoulder-height. The sharply dihedraled 'butterfly'-like twin rudder arrangement kept the tail surfaces clear of the jet efflux. The cockpit was completely faired into the fuselage contour, with a rounded clear nose-cone on the front of the aircraft. Behind this was the actual "window," a large armored-glass plate located some distance behind the extreme nose; the glazing extended almost to the wing root. The design in terms of engine mounting and tailplane bore a very strong resemblance to the contemporary Volksjäger design competition winner, the Heinkel He 162Spatz. The basic A model carried one bomb; it had no other armament. It was to begin its attack in a shallow dive outside the ships' range of fire, and after reaching a speed of, the pilot would "toss" the bomb at the target using a simple computerized sight, and then climb back out of range. The aircraft was designed to withstand 12 g during pullout. The computerized bombsight was not delivered in time to be fitted to the aircraft. Several other versions of the basic airframe were proposed as well. The Hs 132B used the Junkers Jumo 004 engine in place of the BMW 003, and added two MG 151/20 cannons. The HS 132C was a more extensively modified version intended for bomber interception, featuring the larger Heinkel HeS 011 engine, two 151/20s and two MK 103 or MK 108 cannons. The HeS 011, intended to power a wide variety of new and existing Luftwaffe aircraft, was still in the pre-production phase when the war ended. It was hoped that by the time the HS 132B became available, the Panzerblitzanti-tank missile would be in production and available for use. The Hs 132D included a new wing of increased span. A contract for six prototypes was approved in May 1944, and construction was begun in March 1945. Hs 132V1 was scheduled to have its first flight in June 1945, but the completed wings and fuselage were never mated, and Soviet forces captured the intact fuselage in May 1945 while the wings were never moved from their factory in France.
