The Akaflieg Darmstadt D-39 was a single-seat

motor glider A motor glider is a fixed-wing aircraft that can be flown with or without engine power. The FAI Gliding Commission Sporting Code definition is: a fixed-wing aerodyne equipped with a means of propulsion (MoP), capable of sustained soaring flight ...

derived from the D-38

sailplane A glider or sailplane is a type of glider aircraft used in the leisure activity and sport of gliding (also called soaring). This unpowered aircraft can use naturally occurring currents of rising air in the atmosphere to gain altitude. Sailplan ...

. Built in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

in the late 1970s, it was not intended for production and only one was constructed.

Design and development

The D-39 was a motorised version of the D-38 sailplane, with wings moved down from the latter's

shoulder-wing A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...

position to the bottom of 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 aircraft t ...

. A Limbach SL 1700

flat four engine A flat-four engine, also known as a horizontally opposed-four engine, is a four-cylinder piston engine with two banks of cylinders lying on opposite sides of a common crankshaft. The most common type of flat-four engine is the boxer-four engine, ...

was conventionally mounted in the nose; the propeller could be removed but not folded away in flight. The wings, with 4° of dihedral, tail and

monocoque Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell". First used for boats, ...

fuselage were formed from

glass fibre Glass fiber ( or glass fibre) is a material consisting of numerous extremely fine fibers of glass. Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the inventio ...

balsa ''Ochroma pyramidale'', commonly known as the balsa tree, is a large, fast-growing tree native to the Americas. It is the sole member of the genus ''Ochroma''. The tree is famous for its wide usage in woodworking, with the name ''balsa'' being ...

sandwiches and the

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 Flight dynamics, roll (or ...

from glass fibre/ Klégécel foam sandwiches. The D-38 had an all moving T-

tailplane A tailplane, also known as a horizontal stabiliser, is a small 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 and gyroplane ...

, fitted with a Flettner tab. It landed on a retractable

monowheel A monowheel, or uniwheel, is a one-wheeled single-track vehicle similar to a unicycle. Hand-cranked and pedal-powered monowheels were patented and built in the late 19th century; most built in the 20th and 21st century have been motorized. ...

, fitted with a

drum brake A drum brake is a brake that uses friction caused by a set of shoes or pads that press outward against a rotating cylinder-shaped part called a brake drum. The term ''drum brake'' usually means a brake in which shoes press on the inner surfac ...

and assisted by a small, fixed tailwheel. The D-39 was first flown on 28 June 1979. By July 1982 it had been modified into the D-39b, with a greater span, revised wing roots and fitted with two-bladed

Hoffmann Propeller Hoffman Propeller is a German manufacturer of aircraft propellers. The company headquarters is located at Rosenheim in Bavaria, Germany.Purdy, Don: ''AeroCrafter - Homebuilt Aircraft Sourcebook'', page 84. BAI Communications. The company makes d ...

airscrew and three pitch positions. The „D-39HKW“ was developed on the fuselage of the D-39, using 20-Meter flapped wing V

Variants

;D-39: Original version ;D-39b: Same aircraft modified with greater span, revised roots and a new propeller.

Specifications (D-39)

References

{{Akaflieg Darmstadt aircraft Motor gliders 1970s German sailplanes Akaflieg Darmstadt aircraft Single-engined tractor aircraft Low-wing aircraft Aircraft first flown in 1979