Dornier Do 17 - Design

Design

The cockpit and forward fuselage had a conventional stepped cockpit and its nose was fully glazed. Early variants had been labelled the "flying pencil" owing to its sleek and continuous "stick-like" lines. As a result of the lessons learned in the Spanish Civil War, the cockpit roof was raised and the lower, or bottom half, of the crew compartment was a typical under-nose "Bodenlafette", abbreviated Bola, inverted-casemate design ventral defensive armament position, a common feature of most German medium bombers. The Bola was extended back to the leading edge of the wings where the lower-rear gunners position and upper-rear gunner position were level with each other. The cockpit layout consisted of the pilot seat and front gunner in the forward part of the cockpit. The pilot sat on the left side, close up to the Plexiglas windshield. One of the gunners sat on the right seat which was set further back to provide room for the 7.92 mm (0.312 in) MG 15 machine gun to be traversed in use. Usually the Do 17 would have a crew of four in the aircraft: the pilot, a bomb-aimer and two gunners. The bomb-aimer would man the MG 15 in the nose glazing and Bola-housed rear lower position. The two gunners would operate the forward-firing MG 15 installed in the front windshield, the two MGs located in the side windows (one each side) and the rearward firing weapon. The cockpit offered a bright and panoramic view at high altitude. The standard ammunition load was 3,300 rounds of 7,92 mm ammunition in 44 double-drum magazines.

The wings were of a broad 55 m² (590 ft²) area and had a span of 18 m (59 ft 0⅝ in) and had a flat leading edge which curved in a near-perfect semicircle into the trailing edge. The positions of the wing roots were offset. The leading edge wing root merged with the top of the fuselage and cockpit. As the wing extended backwards, by roughly two-third, it declined downwards at a sharp angle so that the trailing edge wing root ended nearly halfway down the side of the fuselage increasing the Angle of attack. This design feature would exist on all future Dornier bomber designs, namely the Dornier Do 217. The trailing edge was faired into the round fuselage shape. The engine nacelle was also faired into the flaps. The extreme rear of the nacelle was hollow and allowed the flap with an attached vertical slot to fit into the cavity when deployed.

The fuselage was 15.80 m (51 ft 9⅝ in) long. It was thin and narrow which presented an enemy with a difficult target to hit. The fuselage had twin vertical stabilizers to increase lateral stability. The power plant of the Z-1 was to have been the Daimler-Benz DB 601 but, owing to shortages, it was allocated Bramo 323 A-1 power plants. The Bramos could only reach 352 km/h (220 mph) at 1,070 m (3,500 ft). The limited performance of the Bramo 323s ensured the Do 17 could not reach 416 km/h (260 mph) at 3,960 m (13,000 ft) in level flight when fully loaded. The range of the Do 17Z-1 at ground level was 635 nmi (1,176 km); this increased to 1,370 km (850 nm) at 4,700 m (15,500 ft). This gave an average attack range of 400 nmi (740 km). The introduction of the Bramo 323P increased the Z-2 performance slightly in all areas.

The Dornier did carry an important defensive measure, namely self-sealing fuel tanks to protect fuel stored in the wings and fuselage. This reduced the loss of fuel and risk of fire when hit in action and often made the return journey possible. Oxygen was provided in the form of 20 bottles for crew use during long flights above 3,660 m (12,000 ft).

Communications usually consisted of FuG X, the later FuG 10 (Funkgerät), navigational direction finder PeilG V direction finder (PeilG - Peilgerät) and the FuG 25 IFF and FuBI 1 blind landing devices. The crew communicated by EiV intercom. A primitive autopilot device, the Siemens K4Ü, was installed that could maintain bearing using the rudder's control surfaces.

The bomb bay accommodated four bomb racks, the No. 5 for SC50 bombs and two ETC 500 racks to carry heavier loads of up to 500 kg (1,100 lb) each. A Lotfe A, or B bombsight was issued together with the BZA-2 aperture (a modernised optical lens system). The aircraft's bomb bay allowed two options. The first was to carry four 250 kg (550 lb) bombs for a load of 1000 kg (2,200 lb), then range would be reduced. If however, the unit decided to carry only half the maximum load of 10 50 kg (110 lb) bombs, then additional fuel tanks could be placed into the forward part of the bomb bay to increase range. The bomb aimer would deploy the bomb load via the Lotfe (A, B or C 7/A, depending on the variant) bomb sight which was situated in the left side of the nose compartment and positioned directly under and forward of the pilot. When fully loaded, the Z-1 weighed 7,740 kg (17,200 lb).