Udet U 7 Kolibri

Last updated
U 7 Kolibri
ETHBIB.Bildarchiv Ans 05338-02-127-AL-FL 91038.jpg
Role Single seat light aircraft
National origin Germany
Manufacturer Udet Flugzeugbau
First flight before mid-1924
Number built 2

The Udet U 7 Kolibri (Hummingbird) was a single engine, single seat, parasol wing light aircraft, designed and built in Germany in the mid-1920s. Though they had some competition success and set an unofficial lightplane duration record, only two were produced.

Light aircraft aircraft with a gross weight of 12,500 lb (5670 kg) or less

A light aircraft is an aircraft that has a maximum gross takeoff weight of 12,500 lb (5,670 kg) or less.

Germany Federal parliamentary republic in central-western Europe

Germany, officially the Federal Republic of Germany, is a country in Central and Western Europe, lying between the Baltic and North Seas to the north, and the Alps to the south. It borders Denmark to the north, Poland and the Czech Republic to the east, Austria and Switzerland to the south, France to the southwest, and Luxembourg, Belgium and the Netherlands to the west.

Contents

Design and development

The wooden, cantilever, two-spar wing of the U 7 was almost trapezoidal in plan, with sweep on the leading edge, out to ellipsoidal tips. It also thinned outwards in section with most of the taper on the upper surface, giving some anhedral. Short ailerons extended to the tips. The wing was mounted over the fuselage on six streamlined steel struts; two upright tripods ran from the forward spar to points on the upper and mid fuselage and two inverted V-struts joined the rear spar to the upper fuselage. [1] [2]

Cantilever beam anchored at only one end

A cantilever is a rigid structural element, such as a beam or a plate, anchored at one end to a support from which it protrudes; this connection could also be perpendicular to a flat, vertical surface such as a wall. Cantilevers can also be constructed with trusses or slabs. When subjected to a structural load, the cantilever carries the load to the support where it is forced against by a moment and shear stress.

Leading edge

The leading edge is the part of the wing that first contacts the air; alternatively it is the foremost edge of an airfoil section. The first is an aerodynamic definition, the second a structural one. As an example of the distinction, during a tailslide, from an aerodynamic point of view, the trailing edge becomes the leading edge and vice versa but from a structural point of view the leading edge remains unchanged.

Fuselage aircraft main body which is the primary carrier of crew, passengers, and payload

The fuselage is an aircraft's main body section. It holds crew, passengers, and cargo. In single-engine aircraft it will usually contain an engine, as well, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage, which in turn is used as a floating hull. The fuselage also serves to position control and stabilization surfaces in specific relationships to lifting surfaces, which is required for aircraft stability and maneuverability.

When the U 7 first appeared in 1924 it was powered by a 13 kW (18 hp) Douglas 500 cm3 (31 cu in) flat twin, mounted in a squared-off cowling with its cylinders exposed for cooling. [3] By June 1924 this had been replaced by a 26 kW (35 hp) Douglas750 cm3 (46 cu in) flat twin. [4] [5] In the summer of 1925, one of the two U 7s built had a 22–25 kW (30–34 hp) ABC Scorpion flat twin, similarly enclosed. [6] [7] Behind the engine the rectangular section fuselage was plywood covered, with an open cockpit under the wing. [2]

Douglas (motorcycles) British motorcycle manufacturer

Douglas was a British motorcycle manufacturer from 1907–1957 based in Kingswood, Bristol, owned by the Douglas family, and especially known for its horizontally opposed twin cylinder engined bikes and as manufacturers of speedway machines. The company also built a range of cars between 1913 and 1922.

ABC Scorpion O-2 piston aircraft engine

The ABC Scorpion is a 30 hp (22 kW) two-cylinder aero engine designed by British engineer Granville Bradshaw for use in light aircraft. The engine was built by ABC Motors Limited and first ran in 1921.

Plywood manufactured wood panel made from thin sheets of wood veneer

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 boards which includes medium-density fibreboard (MDF) and particle board (chipboard).

The Kolibri's tail was conventional, with a trapezoidal plan tailplane and elevators mounted on top of the fuselage and with a quadrantal fin and a rounded rudder that reached down to the keel. [2] It had a very simple, fixed, tailskid undercarriage with the mainwheels on a short single axle held just below the fuselage underside, making the track narrow. [1] [2]

Tailplane 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 gyroplanes

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 gyroplanes. Not all fixed-wing aircraft have tailplanes. Canards, tailless and flying wing aircraft have no separate tailplane, while in V-tail aircraft the vertical stabilizer, rudder, and the tail-plane and elevator are combined to form two diagonal surfaces in a V layout.

Elevator (aeronautics) type of flight control surface

Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's pitch, and therefore the angle of attack and the lift of the wing. The elevators are usually hinged to the tailplane or horizontal stabilizer. They may be the only pitch control surface present, sometimes located at the front of the aircraft or integrated into a rear "all-moving tailplane" also called a slab elevator or stabilator.

Fin flight control surface

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. Fins are also used to increase surface areas for heat transfer purposes, or simply as ornamentation.

ETHBIB.Bildarchiv Ans 05338-02-128-AL-FL 91039.jpg

Operational history

The U 7s took part in several contests. One of the earliest was the August 1924 Rhön meeting for gliders and lightplanes. There were thirty of the latter, though several were motorised gliders rather than sports tourers. [4] The weather was not good, with high winds, and the Kolibri, flown by Udet, was the only one of three powered aircraft to complete the 80 km (50 mi; 43 nmi) round trip from the Wasserkuppe to Kissingen and back, thus winning first prize. [8] [9] In October 1924 Udet, again starting from the Wasserkuppe, flew the U 7 for 4 hr 39 min, an unofficial record for very light aircraft. There was no official recognition of this class of aircraft at the time. [10]

Wasserkuppe Rhön mountain in Germany

The Wasserkuppe (help·info) is a mountain within the German state of Hesse. The elevation, which is a large plateau formation, is the highest peak in the Rhön Mountains. Between the First and Second World Wars great advances in sailplane development took place on the mountain during the interwar period. Near the summit there is still an airfield used by gliding clubs and pilots of light aircraft.

The two Kolibris, fitted with the engines used at the Rhön, flew in the demanding "Round Germany Flight" which began on 9 June 1925. [5] [6] They were expected to do well but the ABC powered machine had to make two forced landings on the first day, resulting in some damage. [6] :360 Neither was amongst the small group from the lowest power class that completed enough circuits to be amongst the prizes; the winner was the Daimler L21. [11]

Daimler L21

The Daimler L21 or Daimler-Klemm L21 was a light twin engined, single seat, parasol winged sports aircraft built in Germany. It was the winner in the lowest powered class of the Round Germany Flight contest of 1925.

Specifications

Data from Flight, July 1924 [1]

General characteristics

Performance

  • Maximum speed: 120 km/h (75 mph; 65 kn)
  • Range: 480 km (298 mi; 259 nmi) [12]
  • Time to altitude: 8 min to 1,000 m (3,300 ft)
  • Landing speed: 50 km/h (31 mph)

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References

  1. 1 2 3 "The Udet "Kolibri" light plane". Flight . XVI (30): 466–7. 24 July 1924.
  2. 1 2 3 4 "Udet-Flugzeugbau G.M.B.H." Flight . XVII (22): 324–5. 28 May 1925.
  3. ↑ "Light 'plane and glider notes". Flight . XVI (37): 564. 11 September 1924.
  4. 1 2 "Light 'plane and glider notes". Flight . XVI (35): 527. 21 August 1924.
  5. 1 2 "Les avions des "Circuit des Airs". Les Ailes (207): 1. 4 June 1925.
  6. 1 2 3 "Power plants". Flight . XVII (24): 357, 360. 11 June 1925.
  7. ↑ Lumsden, Alec (1994). British Piston Aero-engines and their Aircraft. Shrewsbury: Airlife. p. 54. ISBN   1 85310294 6.
  8. ↑ "Light 'plane and glider notes". Flight . XVI (36): 554. 4 September 1924.
  9. ↑ Frachet, André (28 August 1924). "A la Rhön" (167): 3.
  10. ↑ "L'avionette Udet a volé 4h. 39min" (173). 9 October 1924: 1.
  11. ↑ "The round-Germany flight". Flight . XVII (25): 3370. 18 June 1925.
  12. 1 2 "L'avionette Udet". Les Ailes (165): 2. 14 August 1924.
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