The LFG Roland D.IX was a

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

single seat

fighter aircraft Fighter aircraft (early on also ''pursuit aircraft'') are military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air supremacy, air superiority of the battlespace. Domina ...

, a

biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...

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. Three slightly different prototypes were built but there was no series production.

Design and development

Late in 1917 new, more powerful

s were appearing and the

Idflieg The Idflieg (''Inspektion der Fliegertruppen'' - "Inspectorate of Flying Troops") was the bureau of the German Empire that oversaw German military aviation prior to and during World War I. Founded in 1911, the Idflieg was part of the ''Fliegert ...

encouraged aircraft manufacturers to incorporate them into fighters. The D.IX was LFG Roland's response. Apart from its engine it had much in common with the earlier D.VI, D.VII and D.VIII designs. It was a two bay biplane, with straight wings of constant chord and blunt tips. The upper plane was a little larger in both span and chord, so the two

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 struts, which act in ...

s on each side diverged slightly upwards and leant gently outwards. Bracing was assisted by

flying Flying may refer to: * Flight, the process of flying * Aviation, the creation and operation of aircraft Music Albums * '' Flying (Cody Fry album)'', 2017 * ''Flying'' (Grammatrain album), 1997 * ''Flying'' (Jonathan Fagerlund album), 2008 * ...

and

landing wires Landing is the last part of a flight, where a flying animal, aircraft, or spacecraft returns to the ground. When the flying object returns to water, the process is called alighting, although it is commonly called "landing", "touchdown" or "Spla ...

. There were

ailerons An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around ...

on the upper wing only, the first and third prototypes using the overhung, balanced type and the second with unbalanced ones ending at the wing tip. The D.IX had a

fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...

of the ''Klinkerrumpf'' (clinker-built fuselage) type, roughly circular in cross section and built from overlapping longitudinal strips of

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over a light, wooden frame, pioneered by LFG on the D.IV and used on the D.VI, D.VII and D.VIII. Because of the shortness and large diameter of the Siemens-Halske Sh.III geared rotary of the first prototype, the nose of the new fighter was short and blunt compared with those of the earlier aircraft, which had all used liquid cooled

V engine A V engine, sometimes called a Vee engine, is a common configuration for internal combustion engines. It consists of two cylinder banks—usually with the same number of cylinders in each bank—connected to a common crankshaft. These cylinder ...

s. Nonetheless, the metal oil deflecting

cowling A cowling (or cowl) is the removable covering of a vehicle's engine, most often found on automobiles, motorcycles, airplanes, and on outboard boat motors. On airplanes, cowlings are used to reduce drag and to cool the engine. On boats, cowlings ...

was carefully blended into the wooden fuselage. The rotary engine drove a four blade

propeller A propeller (often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon a working flu ...

, an unusual feature at this time and only fitted to one other LFG fighter, the later D.XVI. The

tailplane A tailplane, also known as a horizontal stabilizer, is a small lift (force), lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters ...

of the fighter was straight edged with blunt tips and slightly rounded, split

elevator An elevator (American English) or lift (Commonwealth English) is a machine that vertically transports people or freight between levels. They are typically powered by electric motors that drive traction cables and counterweight systems suc ...

s. Its vertical tail repeated the small

ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. F ...

of the D.VI and later Rolands and the

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

was similarly deep and rounded, but the tail surfaces of the second prototype were much enlarged and the rudder of the third

horn balanced Horn may refer to: Common uses * Horn (acoustic), a tapered sound guide ** Horn antenna ** Horn loudspeaker ** Vehicle horn ** Train horn *Horn (anatomy), a pointed, bony projection on the head of various animals * Horn (instrument), a family o ...

. The D.IX's

conventional undercarriage Conventional landing gear, or tailwheel-type landing gear, is an aircraft undercarriage consisting of two main wheels forward of the center of gravity and a small wheel or skid to support the tail.Crane, Dale: ''Dictionary of Aeronautical Ter ...

was of the single axle type, mounted on V-struts to the lower fuselage and with a tailskid attached to the ventral fin. As well the ailerons and empennage revisions of the later prototypes, both were powered by the newer, Siemens-Halske Sh.IIIa rotary.

Operational history

The first prototype flew in the first D type competition, held in January 1918, and performed well but was lost soon after in an accident in which the pilot's seat collapsed, followed by an inadvertent loop with g-forces that expelled him through the fuselage bottom. The armed second prototype continued development and took part in the second D type competition held in May. There it was judged not worthy of series production.

Specifications

References

Bibliography

* {{Idflieg D-class designations Biplanes 1910s German fighter aircraft LFG Roland D.IX Rotary-engined aircraft Aircraft first flown in 1918