ALVIS LEONIDES Type 503/5 This project was led by Robin Byers.  The ALVIS company was founded in 1919 as T G John Ltd. Late in 1921 the name became The ALVIS Car & Engineering Co. Ltd. The name is believed to reflect the company’s skill in the use of aluminium in its products. T G John, was a Welshman, he founded his company in Coventry to build sports and racing cars, he remained with the company until 1944 being responsible for the financial and business affairs of the company, others being employed to be responsible for design and production. The Company first became interested in aero engines, at the behest of the Government, in the mid 1930s but none of the prototype engines it produced went into production before the war. During the war the Company made a significant contribution to the war effort as a sub-contractor, particularly to Rolls-Royce. The Company’s car factory was severely damaged by the Luftwaffe in a raid on Coventry in 1940, the aero engine factory escaping serious damage. In 1944 the Company accepted a contract from the Ministry of Aircraft Production (MAP) to produce a replacement for the Armstrong Siddeley Cheetah, a medium powered engine that had served the RAF very well during the war. The new engine was based on one of the Company’s pre-war prototypes the Alvis 9ARS Leonides, which itself owed something to the French company Gnome le Rhone with whom Alvis had had a licensing agreement. Prototype engines were produced and flown, the first production engines flew in 1948. Many variants of the Leonides engine were produced including a 14 cylinder two row version. The engine was widely used in both fixed wing aircraft and helicopters for over twenty years and was in production until the late 1960s, many thousands being produced. By the late 1960s Alvis had stopped making both cars and aero engines but were a very successful manufacturer of armoured fighting vehicles. The company then had a succession of different owners until finally BAE Systems took the company over and the name ALVIS was dropped. SPECIFICATION OF THE LEONIDES ALVIS Type No. 503/4 RAF Designation Mk 125 9 cylinders, two valves per cylinder Bore 4.8 in. stroke 4.41 in. (over square) Take off power 550 hp at 3000 rpm Capacity 11.8 litres compression ratio 6.5 Single stage centrifugal supercharger Fuel injection into the eye of the supercharger Weight 815 lb, Diameter 41.5 in. Length 54.4 in. Three bladed Dowty Rotol propeller TRAILER The trailer on which the Leonides and on which our other engines have been mounted is of a unique design developed by Robin Byers and built by members of Aero Engines Carlisle. The trailer is available in three sizes dependent on the intended application. The trailers use beam axles mounted on twin inter linked leaf springs. The two tubes which form the backbone of the trailer also double as fuel and oil tanks. The triangular box section which binds the two structural tubes together also has a double function as the location of the starting batteries and other engine ancillaries. A fourth variant used for the Hercules engine uses rectangular steel tubing for the main structural members and Peakride rubber suspension and brakes. |