A characteristic feature of the German policy in aviation has been the adoption of a certain model of machine and its use in large numbers until such time us it is displaced by a later type. The Rumpler biplane, affords a typical instance of this. During the second year of the war it very largely employed, as is evidenced by the fact that the majority of the machines captured by the French during most of 1916 and the early part of 1917 were Rumplers. Its general characteristics
Top Speed: 95 m.p.h.
Engine: 165-h.p. Mercedes D III
Wingspan: 40.2 feet
Weight: 2,867 lb. loaded
Armament: 2 machine guns
Specifications from “Practical Aviation,” by Charles Hayward, 1919
Planes
The Rumpler has a span of 40.2 feet on the upper plane and 36.08 feet on the lower, the total supporting surface being 381.6 square feet. The wings taper slightly from the butt end at the fuselage toward the tips, the chord varying from 5.74 feet to 5.31 feet, while the gap is 5.75 feet. There is no stagger, the struts being vertical. Both planes are set at a dihedral angle of 2 degrees. In accordance with the usual German practice, the ailerons are attached to auxiliary spars instead of being hinged to the rear beams of the wing itself. They are operated by the usual bell- crank lever projecting through a slot in the wing, this lever being relied on to produce an upward movement of the aileron, while a cable attached near the trailing edge of the aileron is used to give the downward movement. The wings have an angle of incidence of 5 degrees next to the fuselage.
Tail Unit
Steel tubing is employed almost entirely for the framing of the essentials of the tail unit, the horizontal stabilizer being supported about midway of its length by a tube rising on each side from the lower longeron of the fuselage, while at its trailing edge, where it forms the hinge for the elevators, it is further braced by similar tubes attached to the rudder post. The horizontal stabilizer is of the standard triangular form and measures slightly over 11 feet in span along its trailing edge, while the vertical tail fin is very short, being approximately 3.7 feet along the fuselage by 2.7 feet high at the rudder. The latter, however, has an over-all height of 3.7 feet.
Fuselage
The usual seating practice is reversed by placing the pilot in the forward cockpit, while the observer occupies the rear. This second cockpit is equipped with a swiveling seat and a circular rack on which the machine gun is mounted, so that as the gunner varies the aim of his piece he moves around with it. From the nose of the machine to a point just back of the observer’s seat, the four main longerons of the fuselage are of ash, while aft of that point they are of spruce. The engine is braced in place on its ash beams by steel tubes which are practically a continuation of the forward tube struts of the
Landing Gear
Depending on whether it is fitted out as a “bomber” or as a destroyer, the Rumpler biplane carries a release gear for six heavy bombs and a light gun for defense only or two machine guns of a heavier type. The only unusual feature of the instrument equipment is the location of the compass in an inverted position under the upper the upper right wing. For landing in a restricted space, the axle of the landing gear is provided with a brake which acts on the principle of the plow and is operated by means of cable from the forward cockpit.
Power Plant
The motor employed is the 165-h.p. Mercedes, which develops its normal output at 1400 r.p.m. but which on a bench test showed as high as 174 h.p. at 1450 r.p.m. The propeller measures 9.1 feet in diameter and has a pitch of 6.2 feet, though this applies only to a particular machine, since others of the same type that have been captured have differed more or less in detail. The weight of the motor is 676 pounds, while the propeller weighs 41.5 pounds. Fuel is carried in a main tank forming the pilot’s seat and from this tank is raised by a pump to a gravity tank fitted between the forward and rear main wing beams and attached to the central inverted struts from the fuselage.
Just in front of this gravity fuel tank is placed the radiator, fitting in a space between the forward main spar and the leading edge of the wing which it has been designed to fill. A three-way valve is inserted in the main fuel line so that gasoline may be fed either from the main tank directly by pressure or from the gravity tank. The weight of the fuel carried is 374 pounds and the necessary water weighs 55 pounds.