Heinkel He 111

The design of the He 111 A-L initially had a conventional stepped cockpit, with a pair of windscreen-like panels for the pilot and co-pilot. The He 111P and subsequent production variants were fitted with a fully glazed cockpits, laterally asymmetric nose, with the port side having the greater curvature for the pilot, offsetting the bombardier to starboard. The resulting stepless cockpit, which was a feature on a number of German bomber designs during the war years in varying shapes and formats, no longer had the separate windscreen panels for the pilot. Pilots had to look outside through the same bullet-like glazing that was used by the bombardier and navigator. The pilot was seated on the left and the navigator/bomb aimer on the right. The navigator went forward to the prone bomb-aiming position or could tilt his chair to one side, to move into the rear of the aircraft. There was no cockpit floor below the pilot's feet—the rudder pedals being on arms—giving very good visibility below. Sliding and removable panels were manufactured into the nose glazing to allow the pilot, navigator and or bomb aimer to exit the aircraft quickly, without a time-consuming retreat into the fuselage.

The fuselage contained two major bulkheads, with the cockpit at the front of the first bulkhead. The nose was fitted with a rotating machine gun mount, offset to allow the pilot a better field of forward vision. The cockpit was fully glazed, with the exception of the lower right section, which acted as a platform for the bombardier-gunner to be positioned. The commonly-used Lotfernrohr-series bombsight penetrated through the cockpit floor into a protective housing on the external side of the cockpit.

Between the forward and rear bulkhead was the bomb bay, which was constructed with a double-frame to strengthen it for carrying the bomb load. The space between the bomb bay and rear bulkhead was used up by Funkgerät radio equipment and contained the dorsal and flexible casemate ventral gunner positions. The rear bulkhead contained a hatch which allowed access into the rest of the fuselage which was held together by a series of stringers. The wing was a two spar design. The fuselage was formed of stringers to which the fuselage skin was riveted. Internally the frames were fixed only to the stringers which made for simpler construction but at the loss of some rigidity.

The wing leading edges were swept back to a point inline with the engine nacelles, while the trailing edges were angled forward slightly. The wing contained two 700 L (190 US gal) fuel tanks between the inner wing main spars, while at the head of the main spar the oil coolers were fitted. Between the outer spars, a second pair of reserve fuel tanks were located carrying an individual capacity of 910 L (240 US gal) of fuel. The outer trailing edges were formed by the ailerons and flaps, which were met by smooth wing tips which curved forward into the leading edge. The outer leading edge sections were installed in the shape of a curved "strip nosed" rib, which was positioned ahead of the main spar. Most of the interior ribs were not solid, with the exception of the ribs located between the rear main spar and the flaps and ailerons. This was of solid construction, though even they had lightening holes.

The control systems also had some innovations. The control column was centrally placed and the pilot sat on the port side of the cockpit. The column had an extension arm fitted and had the ability to be swung over to the starboard side in case the pilot was incapacitated. The control instruments were located above the pilot's head in the ceiling which allowed viewing and did not block the pilot's vision. The fuel instruments were electrical. The He 111 used the inner fuel tanks closest to the wing root. The outer tanks acted as reserve tanks. The pilot was alerted to the fuel level when the tank had 100 L (26 US gal) left. A manual pump was available in case of electrical or power failure but the delivery rate of just 4½ L (1.2 US gal) per minute demanded that the pilot fly at the lowest possible speed and just below 3,048 m (10,000 ft). Fortunately, the He 111 handled well at low speeds.

The defensive machine gun positions were located in the glass nose, the flexible ventral, dorsal and lateral positions in the fuselage and all offered a significant field of fire.[16] The design of the nose allowed the machine gun position to be moved 10° upwards from the horizontal and 15° downwards.[16] The gun could traverse some 30° laterally. Both the dorsal and ventral machine guns could move up and downwards by 65°. The dorsal position could move the 13 mm (.51 in) MG 131 machine gun 40° laterally, but the ventral Bola-mount 7.92 mm (.312 in) twinned-up MG 81Z machine guns could be moved 45° laterally. Each MG 81 single machine gun mounted in the side of the fuselage in "waist" positions, could move laterally by 40° and could move upwards from the horizontal by 30° and downwards by 40°

Gunston, Bill & Wood, Tony - Hitler's Luftwaffe, 1977, Salamander Books Ltd., London