| CLA.3 | |
|---|---|
 | |
| Role | Racing aircraft |
| National origin | United Kingdom |
| Manufacturer | The Cranwell Light Aeroplane club |
| Designer | Nicholas Comper |
| First flight | mid- July 1925 |
| Retired | 1929 |
| Number built | 1 |
The Cranwell CLA.3 was a parasol winged single-engined, single-seat British aircraft built to compete in the Lympne air races of 1925. It was designed and built by an amateur group drawn from staff and pupils at the RAF College Cranwell. Though it won one prize and set a Class record, only one CLA.3 was made.
The Cranwell Light Aeroplane (CLA) club was formed in 1923 by staff and students at the RAF College Cranwell. The students came from No.4 Apprentices Wing and one of their lecturers, Flt-Lt Nicholas Comper became chief designer of the three aircraft produced by the club as well as one, the CLA.1 that was not completed. [1] Their first finished aircraft, the CLA.2 won a £300 prize at the Lympne trials in 1924, but was a rather slow biplane, and Comper decided to design something much quicker for the 1925 Lympne event. The result was the CLA.3, a single-engined parasol winged single seater. [2] [3] [4]
The wings of the CLA.3 were straight and had constant chord apart from at the rounded tips. [2] The airfoil section used, the Eiffel 371 [5] was something of a novelty, a thick wing with a quite flat bottom. [2] The wings were built on two I-section spruce spars and fabric covered everywhere apart from at the leading edge, where thin aluminium was used. [2] Differential ailerons were fitted; [2] initially the gap between aileron and wing was filled with narrow rubber flaps, but later they were removed as they added weight and made lateral control heavy. [4] The wings were held about 7 in (180 mm) above the fuselage, parasol fashion, by two steel lift struts on each side which ran from a common point on the lower longeron of the fuselage to the front and rear spars at mid-span. [2] Three vertical steel cabane struts on each side joined the centre section to the upper longerons. [2]
The rear part of the fuselage was a Warren girder based on four longerons, tapering towards the tail. The fuselage cross section was kept to a minimum to reduce drag and to this end the pilot sat on the cockpit floor. [2] There were concerns about ease of escape from this position under the rear wing spar, [2] but it was after all, a racing machine. In front of him the structure was wire braced, the longerons converging to become overhung engine bearers. [2] The 32 hp (24 kW) Bristol Cherub II engine was mounted on a plate with a fireproof bulkhead, within a long, smooth aluminium cowling blended into the spinner of the two-bladed propeller. The Cherub's cylinder heads were exposed for cooling. A rounded decking, built up with stringers in the usual way, topped the fuselage from propeller to stern and contained the 4.5 imp gal tank immediately in front of the cockpit, high enough above the engine to allow it to be gravity fed. [2] The overall fin plus rudder shape was not unlike the de Havilland form, though the rudder was not balanced. The tailplane had a straight leading edge inboard, then curved; it could be adjusted in incidence on the ground but not in the air. [2] Its elevators were unbalanced and divided to allow rudder movement. The undercarriage was a simple single axle design using rubber shock absorbers, with the main legs attached to the lower longerons at the same points as the lift struts and braced to the most forward fuselage frame. [2] It was completed with a tail skid.
Nick Comper took the CLA.3 for its first flight in mid-July 1925. [4] The only significant later modification exchanged the geared Cherub II for a direct drive 36 hp (27 kW) Cherub III, fitted with a metal propeller. [4]
Comper was still getting to know the CLA.3 when he flew it at the Royal Aero Club (RAC) race meeting Lympne in August 1925. [6] It was the only new aircraft there. [2] Several of the races were handicaps and did not reward the CLA.3, but it did win the Single-Seater Light 'Plane Scratch Speed Race and the accompanying £50 prize, albeit against only three other competitors. [6] There was also a series of competitions to establish records in the light aeroplane Class, defined by the RAC as those with an engine weight of less than 170 lb (77 kg). [6] The CLA.3 was the fastest out of a field of nine over 3 km, at a speed of 139.89 km/h. (86.9 mph). The same group of aircraft competed over 50 km, and here the CLA.3 came a close second at 135.5 km.h. (84.25 mph). [6] In 1926, fitted with the Cherub III it flew in the King's Cup Race, but engine failure forced it out. [3] [4] The sole CLA.3 was scrapped in 1929. [3] [4]
Data fromFlight 30 July 1925 p.484-7 [2]
General characteristics
Performance
The ANEC I and ANEC II were 1920s British single-engine ultralight aircraft designed and built by Air Navigation and Engineering Company Limited at Addlestone Surrey. One was privately constructed in Brisbane, Australia.
The Bristol Type 91 Brownie was a light sports aircraft produced in the United Kingdom by the Bristol Aeroplane Company in 1924. It was a low-wing cantilever monoplane aircraft of conventional configuration with fixed tailskid undercarriage. The pilot and passenger sat in tandem open cockpits. It won the £1,000 pound prize for second place at the Lympne light aircraft trials in October 1924.
The Parnall Pixie was a low powered British single-seat monoplane light aircraft originally designed to compete in the Lympne, UK trials for motor-gliders in 1923, where it was flown successfully by Norman Macmillan. It had two sets of wings, one for cross-country flights and the other for speed; it later appeared as a biplane which could be converted into a monoplane.
The Beardmore Wee Bee was a single-engined monoplane built only once and specifically for the Lympne two-seat light aircraft trials held in the United Kingdom in 1924. This plane won the major prize.
The Cranwell CLA.4 was a single-engined two-seat inverted sesquiplane designed and constructed for the 1926 Lympne trials by an amateur group from RAF College Cranwell. Two were entered, though engine problems prevented one from taking part; the other was eliminated with a broken undercarriage. A third aircraft was amateur-built in Canada and flew until 1934.
The Cranwell CLA.2 was a single-engined two-seat biplane built by staff and students of RAF College Cranwell as an entrant to the Lympne Two Seater Light Aeroplane Trials of 1924. It won the reliability prize.
The RAE Hurricane was a single-seat, single-engined light monoplane designed and built by the Aero Club of the Royal Aircraft Establishment for the 1923 Lympne Motor Glider Competition. It was underpowered with an unreliable engine. Re-engined, it flew in many races, with first place in the 1926 Grosvenor Challenge Cup its greatest success.
The RAE Scarab was a light single-engined single-seat parasol winged modification of the de Havilland Humming Bird, flying in the United Kingdom in 1932. Only one was built.
The Handasyde monoplane was a single-seat light aircraft built for the 1923 Lympne motor glider competition. It competed there but won no prizes.
The Shackleton-Murray SM.1 was a single-engined two-seat light aircraft designed in Britain and flying in 1933. It was a pusher driven parasol winged monoplane. Only one was built.
The Parnall Possum was an experimental triplane, with a single, central engine driving wing-mounted propellers via shafts and gears. Two of these British aircraft were built in the mid-1920s.
The Clarke Cheetah was a single-engined amateur built aircraft built in the UK using some parts from a de Havilland Humming Bird to produce a machine that could fly either as a biplane or as a parasol winged monoplane. The single example flew for five years before being converted again in 1936.
The Comper Streak was a single-engined, single-seat racing monoplane built in the UK in the mid-1930s. It was not successful as a racer and only one was produced.
The Comper Kite was a single-engined, two-seat touring monoplane built in the UK, derived from the contemporary Comper Streak racer. Only one was built.
The Surrey Flying Services AL.1 was a single-engined side-by-side two-seat training biplane, built at a UK flying club in 1929. Only one was built, but it was flying until the outbreak of war in 1939 and remains in storage.
The Koolhoven F.K.44 was a two-seat, single engine sport monoplane designed and built in the Netherlands in the early 1930s. It was built to order, but only one was completed.
The Leduc RL-12 was a French low power, economical, parasol wing, single seat aircraft. First flown in July 1939, its development was halted by World War II.
The Cranwell Light Aeroplane Club was formed in 1923 by staff and students of the RAF College Cranwell to design and build light aircraft. One of the members was Flight Lieutenant Nicholas Comper who became the Chief Designer. Comper and the club designed and built four aircraft with the last three types being flown.
The Silesia S-4 was a Polish, low-power parasol wing aircraft built in 1925. After an engine change and airframe modifications it became one of the Silesian Aeroclubs fleet. It was lost in a take-off accident in 1931 and was the last Silesia aircraft to fly.
The Brown 1926 parasol monoplane was a 1920s US, three seat, parasol wing civil aircraft developed from a biplane wartime scout. It was intended for either the private or commercial passenger markets, though one was used as a crop-duster.