MEDWAY AIRCRAFT PRESERVATION SOCIETY Ltd
We restore and preserve historic aircraft and artefacts for public display.
Patron: Her Majesty The Queen
Bristol Hercules XII Engine
The Bristol Hercules was designed by Sir Roy Fedden and produced by the Bristol Engine Company with manufacturing starting in 1939. It was the first of the company's "sleeve valve" designs to see widespread use. The 14-cylinder radial aircraft engine is air-cooled and has sleeve valves in the cylinder walls which increases the efficiency by eliminating the traditional valves in the cylinder heads. It was first used to power aircraft such as the Bristol Beaufighter, Handley Page Halifax and Short Stirling bombers that were flying in the early years of World War II and later versions powered other military bomber and transport aircraft as well as several types of early post-war civil airliners. The cylinders are in two banks of seven, rotated with respect to each other for optimal cooling and each bank has its own master connecting rod and six other connecting rods. An in-line epicyclic reduction gearbox is mounted on the front in order not to obstruct the air flow to all cylinders as can be seen in these two images.
MAPSL undertook the preservation of this Bristol Hercules Mk XII engine from the RAF Museum’s Halifax between 1994 and 1999. This version had a single-stage supercharger and developed 1380 HP.
Bristol Pegasus XVIII Engine
The Pegasus engine was a nine-cylinder air-cooled radial engine designed by Roy Fadden in 1932 for the Bristol Aeroplane Company, being developed from the earlier Mercury and Jupiter engines. It was used on various military aeroplanes during World War II including the Fairey Swordfish, Handley Page Hampden, Hawker Hart, Short Sunderland and Vickers Wellington, and also in several civilian designs, developing about 900 HP in normal flight conditions. The cylinders are in a single bank with a master connecting rod and eight articulated connecting rods mounted on it. An in-line epicyclic reduction gearbox is mounted on the front in order not to obstruct the air flow to all cylinders as can be seen in these two images.
This Bristol Pegasus XVIII engine comes from the RAF Museum’s Handley Page Hampden and was restored that by MAPSL between 2001 and 2009. The two images clearly show what can be achieved by a team of dedicated volunteers working to the highest standards and not cutting any corners. The lengthy timescale for this project resulted in part from the work being taken in parallel with other projects; however, the results were well worth the wait and reflected the effort that was put into the preservation by the members.