Junkers Ju 87 D/G vol. I


A three-section inverted gull wing featured two main spars and was of all metal construction. Its characteristic flattened “W” shape was achieved by attaching two dihedralled outboard sections to the anhedralled center section. The wing had a trapezoid planform with rounded wingtips. The wing’s center section was permanently attached to the fuselage structure. Two coolant radiators were placed under the wing’s center section. Outboard wing sections were attached to the center section with for universal ball joints designed by Junkers. The aircraft featured stressed sheet duralumin skins. The wing was equipped with two-piece wing flaps behind the trailing edge of the center and outboard sections. The flaps and single- piece, trimmable ailerons were attached to the wing by patented Junkers support devices. Ailerons were operated mechanically, while flaps featured hydraulic actuation. All elements of the wing’s mechanization were covered with smooth duralumin skins. The aileron-flap system was a unique Junkers design called Doppelflügel, or “double wing”. That arrangement was technologically simple and the slotted flaps and ailerons increased the system’s effectiveness. Automatically actuated, slotted dive brakes were placed under the wing, near the number 1 wing spar. Those devices were used in automatic dive recoveries.

 

Three types of field modifications to cockpit’s armor plating – first one included additional armour plates for both crew stations. Most likely, modifications similar to this one were very common. [Visualisation 3d Marek Ryś]

The tailplane was of an all-metal design with smooth, duralumin skins. The vertical fin had a trapezoid shape and featured a rudder operated by steel control cables. Trimmable horizontal stabilizer with neutral dihedral had a rectangular planform and was braced by steel tube struts with duralumin fairings. The elevator was actuated by a system of push-rods. Both rudder and elevator were aerodynamically and mass balanced and featured trim tabs.
Conventional, fixed landing gear with a tail wheel provided good ground handling. The single-strut main landing gear was attached near number 1 wing spar at the junction of the wing’s center and outboard sections. KPZ main landing gear struts manufactured by Kronprinz featured a fork and oleo shock absorbers with additional spring damping. The main wheels were covered by characteristically shaped fairings, one of Stuka’s most recognizable features. A set of 840x300 mm tires was mounted on the main landing gear wheels. Recommended operating pressure for the tires was 0.25 MPa. The aircraft had hydraulic drum brakes on the main wheels which used F1- Drucköl brake fluid. The tail wheel assembly was attached to a horizontal frame placed between fuselage frames 15 and 16. The wheel was attached to a Kronprinz strut and fork which was spring-damped. The tail wheel strut had a 360° free-castoring capability. The tail wheel rim was designed to accept a 380x150 mm tire with recommended operating pressure of 3 to 3.5 atm. The tail wheel could be locked for take-off, landing and in-flight by means of a control cable running to the cockpit. Technical inspection of the landing gear was recommended after every 500 cycles. The aircraft was also equipped with a tail skid to protect the empennage during emergency landings. For winter operations the aircraft could be equipped with skis in place of landing gear wheels. The kit consisted of a set of three skis with plywood fairings. The main skis were 3,780 mm long, 1,025 mm wide and 519 mm high. The tail ski dimensions were 1,005x440x200 mm respectively.
The powerplant was a Junkers Jumo 211 J-1 engine developing 1,420 Hp. It was a twelve cylinder, inverted “V” unit with a two-stage supercharger and fuel injection. The engine featured a 60 degree cylinder angle and had a 35 l working capacity. Each cylinder was 150 mm in diameter, had a piston stroke of 165 mm and produced a 6.5:1 pressure ratio. A dry engine weighed in at 660 kg. The powerplant sat on the engine mount attached at four points to the firewall. Engine start could be performed using a combination hand and electrical inertia starter, which could be activated either by hand-cranking or by a ground power source. Engine cooling was provided by a 1:1 mixture of water and ethylene glycol with 1.5 percent addition of Schutzöl 39 anti-corrosive fluid. Coolant overflow tank had a capacity of 18 l and was placed on the left side of the engine mount. Two pumps controlled the proper coolant flow. The heat was dissipated through a pair of radiators mounted under the wing’s center section, close to the trailing edge. The counter-clockwise rotating engine drove a clockwise rotating VS 11 propeller with 20° adjustable pitch. The propeller’s diameter was 3,260 mm and it was redlined at 2,250 rpm.