Pobjoy Airmotors

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Pobjoy Airmotors and Aircraft was a British manufacturer of small aircraft engines. They were purchased by Short Brothers shortly before the start of World War II, production continuing until the end of the war.

[edit] History

Douglas Rudolf Pobjoy started in the engine business working with Roy Fedden at Cosmos Engineering just after the end of World War I. Cosmos went bankrupt shortly after the war, with their assets eventually being picked up by Bristol Aeroplane where Fedden would go on to produce a line of extremely successful engines.

Pobjoy also spent time in the RAF as an education officer. Here he met Flight Lt. Nicholas Comper who went on to design the Comper Swift, which would later fly from London to Australia in 9 days 2 hours. Pobjoy partnered with Parnell to develop an engine for the Swift. Although they felt that a cast-block inline engine like the ones being produced by Cirrus and de Havilland would always be less expensive, they nevertheless selected the radial layout for their design, feeling that the cost would be more than offset by the lighter weight and higher performance his designs would offer. Pobjoy later took over the design and started a company of his own to produce it in the Wirral.

The Parnell/Pobjoy design, the 7-cylinder 67 hp Pobjoy P, received its 50-hour type rating in 1928. This was followed in 1929 by the 75/80 hp Pobjoy R, which became very successful, notably on the General Aircraft Monospar. Later designs included the 85/90 hp Pobjoy Cataract, replacing the R, and 130 hp Pobjoy Niagara of 1934. The Niagara was used on a number of designs by Shorts designers, notably the Short Scion Senior and the original half-scale prototype for the Short Stirling, the S.31. The Niagara's compact size excellent performance led to it being used on the Air Ministry's S.23/27 extremely long-endurance prototypes, the General Aircraft GAL.38 and Airspeed AS.39 Fleet Shadowers.

In 1934 Pobjoy moved their plant to Rochester, Kent to be closer to their largest customer, Shorts. The move, and the ongoing effects of the Great Depression, drove the company into financial difficulty, and it was eventually bought outright by Shorts. Douglas Pobjoy then moved on to designing de-icing equipment for high-altitude flights.

After the war Pobjoy designed a new tractor. On 4 July 1948 he was returning from a sales trip to Helsinki when the Scandinavian Airlines Douglas DC-6 he was flying in collided with an Avro York in clouds over the Northolt Aerodrome. All 39 passengers in both planes were killed.

[edit] Note

According to Jane's Fighting Aircraft of World War II of 1946, the company was made public in 1935.

During the second world war Pobjoy ran a section of Rotol Airscrews of Gloucester, England, responsible for the design and development of an airborne generator, intended for use on the Short Shetland flying boat. The unit consisted of a flat-six sleeve-valve air-cooled petrol engine driving the generator. This was installed inboard on the aircraft, and due to the incorrect closure of the cooling ducts the engine overheated and the resulting fire destroyed the prototype Shetland. It seems that the project was abandoned at this stage

[edit] Designs

• Pobjoy P
• Pobjoy R 80 hp
  • 7 cylinder radial air cooled geared, 2835 cc
• Pobjoy Cataract
• Pobjoy Niagara 90 to 130 hp
  • Mark V - seven-cylinder air-cooled geared radial engine