Thread: Merlins

Seeing the other thread wasn't about aeroplane engines, I thought I would start one on them. I have always had an interest in these engines, because my father spent most of the war building them or tooling for them.

Rolls Royce had reluctantly got into the aeroplane engine business in about 1915, and by the end of the first war had in production the Eagle, a V12 producing 360hp from 20l, and was considered at least the equal of anything else comparable. This had separate cylinders, and was replaced by the similar sized Kestrel with a cast cylinder block in 1927, producing 490hp. For the Schneider Trophy races in 1929, they produced the 37l Rolls Royce R engine. This produced 2500hp (on special racing fuel, with an engine life measured in (single digit) hours, after a major effort to get oil consumption down to 50 gallons an hour.

Using their experience with the 'R', the Kestrel was enlarged in 1934 to produce the Merlin 1, which produced 790hp from 27l. This became one of the most successful aeroplane engines of the period. Power continually increased until by 1946 it was producing up to 2030hp, although the most widely used variants produced around 1700hp.

It powered most of Britain's military aircraft in WW2, including Hurricane, Spitfire, Lancaster and Mosquito, as well as the most successful US fighter of WW2, the P51. It was built by Rolls Royce, plus a number of shadow factories in Britain, Packard in the US, and CAC in Sydney.

Technically, it was a V12 with a single overhead camshaft operating four valves per cylinder via rockers. It had a geared centrifugal supercharger and a geared propeller reduction.

Post war it was used in civilian aircraft to some extent (Avro Lancastrian and Canadair GM-54), but was not really successful. A land version called the Meteor was used in tanks in the postwar period, and it was also used in high speed naval motor boats in a marine version built by Packard. Postwar it was use in air racing and boat racing, in some cases producing power way beyond anything the manufacturers dreamed of.

On a personal note, one of my treasured tools is a screwdriver made from a Merlin head bolt that failed QC. It is about two feet long with a cast alloy handle, and has been in use for over sixty years.

John

Yes isuzurover was first with the longnose reference.

I think using the R380 will only delay greabox failure by about 2 days.

It's a lovely looking thing but probably just built for show.

(And very gentle acceleration!)