Sir Roy Fedden was Chief Design Engineer at Bristol Airplane Co. for many years, especially dedicated to sliding-sleeve valve engines, the famous Hercules, Centaurus etc. Own designs are known as a turboshaft and a turbojet, the "Costwold" (see Interavia 1947, A II, no 10, page 31 to 35).

-His own company, "Roy Fedden Ltd." in Stoke Orchad, near Chetelham, Glos., founded in 1945, is known for its horizontal-opposed six-cylinder engines, with sliding sleeve valves.

-The 6AID-325, with double ignition giving 160 hp at 2,750 rpm., was built between 1945 and 1948.

-This engine can be seen at the Museum of Science in London.

-The G6AID-325 is the same engine with gearbox, delivering the same power, 185 hp at 3,400 crankshaft rpm.

From Appendix 6: In the main text, the engine that he designed in 1945, and developed until 1948, is not shown. It is the 6A1D-325 that delivered 160 hp at 2,750 rpm.

"6A1D-325"

-This engine is on display at the Science Museum in London on the top floor, which is dedicated to aviation.

-The engine was to be installed in pusher mode, as we see in the design below.

"Installation with pusher prop"

"The engine fits inside the wing profile"

-The most important feature of the engine was that it used sliding sleeves, which we can check in the following two illustrations:

"Open cylinders"

-See also the chapter for "Roy Fedden", which is the full name of this important English engineer, who in addition to collaborating with other important brands, made his own engines, as we will see. This includes the "Cotswold" turboprop mentioned in this "Fedden" chapter.

"The Cotswold turboprop"

-Initially, its power was between 1,230 and 1,425 hp. And a certain thrust is also assumed.