The Udet U 1 was the first of a line of small, low-powered,

low 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 ...

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 ...

monoplane 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 ...

s built in Germany in the early 1920s.

Design and development

In the summer of 1921, a new aviation company was formed using the

WWI 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 flying ace Ernst Udet's name. William Pohl from Milwaukee, Hans Henry Herrmann and Erich Scheuermann joined the company to fund the aircraft before postwar treaty restrictions were lifted on aircraft production, with the intent of building an inexpensive aircraft for the American market. The builders produced and flew the U 1 five months before the formation of the Udet Flugzeubau GmbH company. The design was a

in an era dominated by

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 ...

s. The U 1 was a single-seater, as the air-cooled,

Haacke HFM-2 The Haacke HFM-2 was a German two cylinder flat engine built in the early 1920s. Variants From Flight * HFM-2 () * HFM-2a (); as HFM-2 apart from bore Applications * Albatros L.66 * Dietrich-Gobiet DP.VII * Działowski D.K.D.1 * Dobi-I ...

flat-twin A flat-twin engine is a two-cylinder internal combustion engine with the cylinders on opposite sides of the crankshaft. The most common type of flat-twin engine is the boxer-twin engine, where both pistons move inwards and outwards at the same ti ...

did not have enough power for more than one person. An enlarged-bore version of the engine, the HFM-2a was used in the two seat U-2. The U-2, like its predecessor, had a one-piece wing with a high aspect ratio of 9. In plan it was

trapezoidal A quadrilateral with at least one pair of parallel sides is called a trapezoid () in American and Canadian English. In British and other forms of English, it is called a trapezium (). A trapezoid is necessarily a convex quadrilateral in Eucli ...

out to angled tips and had light dihedral. It was built around twin wooden

spars The United States Coast Guard (USCG) Women's Reserve, also known as the SPARS (SPARS was the acronym for "Semper Paratus—Always Ready"), was the women's branch of the United States Coast Guard Reserve. It was established by the United States ...

; ahead of the leading spar the wing was

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, forming a torsion-resistant D-box.

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 ...

, which filled about 40% of the

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, 1997. ...

, reached out to the tips. Behind the engine in its

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

cowling the fuselage was structurally rectangular in section apart from raised upper decking and was ply-covered. Pilot and passenger sat in tandem in a single, open cockpit, with the pilot in front and over the centre of the wing. It had a conventional, rather angular tail, with a

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. Fin ...

of greater area than the

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 ...

, though this reached down to the keel; the

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 ...

, mounted on top of the fuselage, was also large compared with the

elevators 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 are ...

. The U 2 had a conventional

undercarriage Undercarriage is the part of a moving vehicle that is underneath the main body of the vehicle. The term originally applied to this part of a horse-drawn carriage, and usage has since broadened to include: *The landing gear of an aircraft. *The ch ...

, with pairs of outward-reaching V-struts from the lower fuselage joined at their vertices by a transverse member, to which the single axle was held by shock absorbing rubber rings. With a passenger the U-2 was slower than the U 1 and clearly under-powered, so the last three variants, the U 4, U 6 and U 10, were fitted with more powerful Siemens-Halske

radial engines 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 cal ...

Operational history

The Siemens-Halske-powered U 6 and U 10 variants sold best, with about 16 built. Flown by Udet, the longer span U 10 was the fastest aircraft in the ''Coupe d'Italie des Avions de Tourisme'' held in November 1924, though criticized for its high landing speed. In 1925 a U 10 came first in the under- class of the ''Deutschen Rundflug''.

Variants

Data from ''German Aviation 1919-1945'' ;Udet U 1 :Single seat prototype with

. One only. ;Udet U 2 :Two seat production variant with

a flat-twin. Four built. ;Udet U 4 :

Siemens-Halske Sh 4 The Siemens-Halske Sh 4 was a five-cylinder, air-cooled, radial engine for aircraft built in Germany in the 1920s. First run in 1921, it was rated at 40 kW (55 hp). Applications * Albatros L 59 * Albatros L 71 * Caspar U.1 * Dietri ...

five cylinder radial powered. One built. ;Udet U 6 :

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 powered with revised, more rounded wing plan and tail surfaces. "Bathtub" cockpit replaced with separate single cockpits. Five built. ;Udet U 10 :

five cylinder radial powered. wingspan. Eleven built. ;Udet U 10a :Floatplane variant with

Siemens-Halske Sh 11 The Siemens-Halske Sh 11 was a seven-cylinder, air-cooled, radial engine for aircraft built in Germany in the 1920s. First run in 1925, it was rated at 75 kW (100 hp). Applications * Albatros L 68 * Bach 3-CT-2 Air Yacht * Bach 3-CT- ...

. One only, possibly a conversion.

Aircraft on display

German Museum of Technology (German Museum of Technology) in Berlin, Germany is a museum of science and technology, and exhibits a large collection of historical technical artifacts. The museum's main emphasis originally was on rail transport, but today it also features e ...

, Berlin: Udet U 10, ''D-452''

Specifications (U 2)

References

External links

Udet U.1

{{Udet aircraft Udet aircraft Low-wing aircraft Single-engined tractor aircraft Aircraft first flown in 1922 1920s German sport aircraft