Jameson Aero Engines Ltd built some horizontally opposed engines that appeared between 1946 and 1950.

-The design began in 1943 and was completed after WWII.

-The first model was the four-cylinder FF that gave 88-92 hp at 2,800 rpm.

-The FF1 engine gave 106 hp at 3,050 rpm and in this case it was fitted with 0.691 to 1 reduction gear.

-The FF4 gave 110 hp. Two of these engines can be seen at the RAF museum in Hendon.

-A 200 hp version with 8 cylinders was also designed.

"Jameson FF1"

-What it shows off, is its small size, the use of gear, and the original distribution for the angled valves.

-FF1 in the figure does not show the induction system, which was on top of it. It was installed on the De la Cierva “Skeeter” prototype and on two DH aircraft.

-We located a drawing of the engine, one of those great cutaways that have been published in the Flight (Flightglobal) magazine. Here we can see all the details.

“Jameson four-cylinder cutaway” (PiP)

From Appendix 6: We did not have a photograph of the Jameson engine until we found it in the English Flight publication.

“Jameson engine” (PiP)

-This engine had inclined valves, an interesting thing for a small and supposedly economical engine. It had interesting mechanisms of rockers, rods and rocker arms.

“Jameson's valve system”

-It had a gearbox of the same unusual type that we have seen in the Allison V-1710 on the P-40 aircraft. The crankshaft drove the teeth of the inner gear of a drum at the end of the propeller shaft.

“Gearbox details”