The

parasol 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 ...

, single engine Udet U 8, sometimes referred to as the Limousine, was a three-seat commercial passenger transport designed and 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 1924. Five were produced and were used by German airlines until about 1928.

Design and development

The first Udet passenger transport was the two-passenger U 5, which appeared in 1923. This was powered by a , seven-cylinder,

Siemens-Halske Sh 5 The Siemens-Halske Sh 5 was a seven-cylinder, air-cooled, radial engine for aircraft built in Germany in the 1920s. First run in 1921, it was rated at 60 kW (80 hp). Applications * Albatros L 60 * Dietrich DP.IIa * Grulich S.1 * Jun ...

radial engine The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ca ...

. The following year Udet produced the first U 8, which had a nine-cylinder,

Siemens-Halske Sh 6 Siemens & Halske AG (or Siemens-Halske) was a German electrical engineering company that later became part of Siemens. It was founded on 12 October 1847 as ''Telegraphen-Bauanstalt von Siemens & Halske'' by Werner von Siemens and Johann Ge ...

radial, making it rather heavier than the U 5 but leaving the design only slightly changed and the dimensions unaltered. The new engine allowed the U 8 to carry three passengers. The

cantilever A cantilever is a rigid structural element that extends horizontally and is supported at only one end. Typically it extends from a flat vertical surface such as a wall, to which it must be firmly attached. Like other structural elements, a canti ...

, one-piece parasol wing of the U.8 was trapezoidal in plan, with long, elliptical tips. It had a thick section which thinned outwards and was built around two

spruce A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfami ...

box spars and fabric covered. Its

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 ...

tapered in chord out to the wing tips; together, they occupied 45% of the span. The wing was mounted a little above 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 ...

on four short

strut A strut is a structural component commonly found in engineering, aeronautics, architecture and anatomy. Struts generally work by resisting longitudinal compression, but they may also serve in tension. Human anatomy Part of the functionality o ...

s, two to each spar, an unusual arrangement used earlier on the U 5 and chosen by its designer, Hans Herrmanns, to improve both the

aerodynamics Aerodynamics, from grc, ἀήρ ''aero'' (air) + grc, δυναμική (dynamics), is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dyn ...

at the wing-fuselage junction and cabin ventilation, a problem in small cabin aircraft of the time. Under the wing, part of the cabin roof was open. The wing struts, uncovered on the U 5, were covered by longitudinal panels. At least three types of

s powered the five U.8s known to have been built. The first examples had the Siemens-Halske Sh 6 but later both nine-cylinder,

Siemens-Halske Sh 12 The Siemens-Halske Sh 12 was a nine-cylinder, air-cooled, radial engine for aircraft built in Germany in the 1920s. First run in 1925, it was rated at 80 kW (110 hp). The Sh 12 was also produced in the United States by Ryan Aeronautic ...

s and a 3-cylinder,

Bristol Lucifer The Bristol Lucifer was a British three-cylinder, air-cooled, radial engine for aircraft. Built in the UK in the 1920s by the Bristol Aeroplane Company, it produced 100 horsepower (75 kW). The Lucifer was originally a Cosmos Engineering ...

. No images of the Bristol installation are known but the German radials were cleanly cowled by the standards of their time, before either

Townend ring A Townend ring is a narrow- chord cowling ring fitted around the cylinders of an aircraft radial engine to reduce drag and improve cooling. Development The Townend ring was the invention of Dr. Hubert Townend of the British National Physica ...

s or

NACA cowling The NACA cowling is a type of aerodynamic fairing used to streamline radial engines installed on airplanes. It was developed by Fred Weick of the National Advisory Committee for Aeronautics (NACA) in 1927. It was a major advance in aerodynamic ...

s had been introduced, and with quite large

spinner Technology *Spinner (aeronautics), the aerodynamic cone at the hub of an aircraft propeller * Spinner (cell culture), laboratory equipment for cultivating plant or mammalian cells * Spinner (computing), a graphical widget in a GUI * Spinner (MIT Med ...

s but with cylinder heads exposed for cooling. One advantage of the gap between fuselage and wing was that the pilot's open

cockpit A cockpit or flight deck is the area, usually near the front of an aircraft or spacecraft, from which a Pilot in command, pilot controls the aircraft. The cockpit of an aircraft contains flight instruments on an instrument panel, and the ...

could be placed under the wing

leading edge The leading edge of an airfoil surface such as a wing is its foremost edge and is therefore the part which first meets the oncoming air.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, ...

rather than set into it, spoiling its aerodynamics. Entry into the

plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...

covered fuselage was through a port-side door under the wing; the three-seat cabin had pairs of windows on each side and a baggage space behind with its own door. At the rear the fuselage became quite slender, with a high mounted, long span, cantilever and almost rectangular plan

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 ...

with high aspect ratio

elevator An elevator or lift is a wire rope, cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or deck (building), decks of a building, watercraft, ...

s. The tailplane incidence could be adjusted in-flight. Its quadrant-shaped fin mounted a

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 aircraft, air or watercraft, water). On an aircraft the rudder is used primarily to ...

which extended down to the keel. The U 8 had fixed, conventional

landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...

of the single axle type which was more refined than that of the U5, with a longer

oleo strut An oleo strut is a pneumatic air–oil hydraulic shock absorber used on the landing gear of most large aircraft and many smaller ones. This design cushions the impacts of landing and damps out vertical oscillations. It is undesirable for an airp ...

to mid-fuselage and rearward drag struts. There was a short tailskid. In about 1925 at least one Udet 8 was fitted with full-span Lippmann/Handley Page slats coupled to full-span ailerons which were lowered together as camber increasing

flap Flap may refer to: Arts, entertainment, and media * ''Flap'' (film), a 1970 American film * Flap, a boss character in the arcade game ''Gaiapolis'' * Flap, a minor character in the film '' Little Nemo: Adventures in Slumberland'' Biology and he ...

s when the slats were deployed. It was one of the earliest German aircraft to have slats. The slatted Udet 8 was recorded as a Udet 8a or Udet 8B in contemporary journals, though a modern source states that the U 8a (''D-839'') had a new wing with an area increase of and a Sh-12 engine. ''D-839'' is recorded as a U 8b in a reconstructed register.

Operational history

In 1925 one U 8, ''D-670'', competed in the "Round Germany Flight", one of only two commercial types to do so. Powered during the contest by the Bristol Lucifer engine (it had a nine-cylinder Siemens at another time), it successfully completed all five circuits of the contest, a total of distance of but, with a more powerful engine than most in its class (C}, was ranked only ninth. Another Udet entrant, the two seat Udet U 10, won class B. The five U 8s were initially used by

Deutsche Aero Lloyd Deutsch or Deutsche may refer to: *''Deutsch'' or ''(das) Deutsche'': the German language, in Germany and other places *''Deutsche'': Germans, as a weak masculine, feminine or plural demonym *Deutsch (word), originally referring to the Germanic ve ...

, but two of them were transferred to Nordbayeriche Verkehrsflug when Aero Lloyd became

Deutsche Lufthansa Deutsche Lufthansa AG (), commonly shortened to Lufthansa, is the flag carrier of Germany. When combined with its subsidiaries, it is the second- largest airline in Europe in terms of passengers carried. Lufthansa is one of the five founding m ...

in 1926. One of these (''D-670'') crashed soon after. It was transferred to the DVS and was joined there by ''D-839'' later in the year.

Specifications (Siemens-Halske Sh 6 engine)

Notes

References

{{Udet aircraft Parasol-wing aircraft Udet aircraft 1920s German civil aircraft Aircraft first flown in 1924 Single-engined tractor aircraft