The Siemens-Schuckert DDr.I was a

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

German German(s) may refer to: * Germany (of or related to) ** Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...

twin engine,

push-pull configuration An aircraft constructed with a push-pull configuration has a combination of forward-mounted tractor (pull) propellers, and backward-mounted ( pusher) propellers. Historical The earliest known examples of "push-pull" engined-layout aircraft incl ...

triplane A triplane is a fixed-wing aircraft equipped with three vertically stacked wing planes. Tailplanes and canard foreplanes are not normally included in this count, although they occasionally are. Design principles The triplane arrangement m ...

fighter aircraft. Only one was built, crashing on its first flight.

Design and development

The unusual DDr.I was one of the first aircraft to have two engines on the same centre line, one in

tractor configuration In aviation, the term tractor configuration refers to an aircraft constructed in the standard configuration with its engine mounted with the propeller in front of it so that the aircraft is "pulled" through the air. Oppositely, the pusher co ...

and the other a pusher, an arrangement usually known as

tandem Tandem, or in tandem, is an arrangement in which a team of machines, animals or people are lined up one behind another, all facing in the same direction. The original use of the term in English was in ''tandem harness'', which is used for two ...

push-pull. It was a

with constant chord, straight edged, square tipped wings of equal span and marked stagger. These were divided into two bays by pairs of near-parallel

interplane strut In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in ...

s. The upper wing was braced over the

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraf ...

with a pair of N-form struts, leaning inward from the upper fuselage to common mountings on the wing centre line. The middle wing of the triplane was positioned at

shoulder The human shoulder is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder mak ...

height on the fuselage and the lower wing passed unbraced below. There were short span ailerons on each wing. The smoothly faired and contoured short fuselage of the DDr.I positioned the open pilot's cockpit between two Siemens-Halske Sh.I nine cylinder

rotary engine The rotary engine is an early type of internal combustion engine, usually designed with an odd number of cylinders per row in a radial configuration. The engine's crankshaft remained stationary in operation, while the entire crankcase and its ...

s, one with a two blade tractor propeller and the other driving a four blade pusher turning just aft of the lower wing

trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 199 ...

. The

empennage The empennage ( or ), also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow.Crane, Dale: ''Dictionary of Aeronautical Terms, third e ...

was mounted on four longitudinal, tubular outrigger beams, braced with vertical and transverse members. There were no fixed rear surfaces; the single piece, constant chord

elevator An elevator or lift is a cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or decks of a building, vessel, or other structure. They a ...

reached between the two upper beams and a pair of similarly shaped

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adve ...

went from the upper to the lower beams, hinged further aft than the elevator but with their lower ends on a hinged frame that moved with it. The DDr.I had a fixed conventional undercarriage, with its mainwheels on a single axle mounted on wide spread V-struts attached to the lower fuselage at the lower corner points of each engine's

firewall Firewall may refer to: * Firewall (computing), a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts * Firewall (construction), a barrier inside a building, designed to limit the spr ...

. Engine control problems and a lack of stability experienced in the first flight, made on 9 November 1917, led to a crash; the aircraft was not rebuilt and plans for a more powerful version, the DDr.II, powered by two , Siemens-Halske Sh.III eleven cylinder

s were abandoned.

Specifications

References

{{Idflieg Dr-class designations Triplanes Twin-engined push-pull aircraft 1910s German fighter aircraft DDr.I Aircraft first flown in 1917 Rotary-engined aircraft