The successor of the great Merlin engine, the Rolls-Royce Griffon played its part in helping to win the Second World War when it was fitted to iconic warbirds such as the Spitfire and Seafire.
Griffon development began in response to a request from the Fleet Air Arm of the Royal Navy in 1938. Navy aircraft tend to be larger and heavier than their land-based counterparts; this obviously puts greater demands on the engine if performance is to be maintained. To meet this demand, Rolls-Royce went back to the concept of the Schnider Air Racing Trophy “R” engine. The Griffon, essentially a modernized Merlin, is a 60 degree V-12 with 2239 cu. in. displacement (the same parameters as the “R” and 36% greater displacement than the Merlin while having an only slightly larger frontal area.) However, this was a totally new engine, featuring many design updates and improvements over the Merlin.
The Griffon was the first Rolls-Royce aero engine to employ a hollow crankshaft as a more efficient method of providing oil distribution to the main and big-end bearings, as opposed to the vulnerable, exposed, external oil distribution lines of the Merlin. Additionally, the camshaft and magneto drives were incorporated into the propeller reduction gears at the front of the engine rather than using a separate system of gears driven from the back end of the crankshaft; this allowed the overall length of the engine to be reduced as well as making the drive train more reliable and efficient.
Fitting the Griffon into a relatively small, light, single-engine aircraft such as the Spitfire created some handling difficulties primarily due to the enormous torque reaction which could amount to a very significant 4700 lb-ft at take-off power. Designing a gear reduction unit for contra-rotating propellers turned out to be the definitive answer after various aerodynamic attempts, such as an enlarged vertical stabilizer, presented only a partial solution. Contra-rotating propellers were essential for the Navy’s Seafire because of the extremely hazardous nature of carrier landings, particularly during a go-round when maximum power might need to be applied at low altitude and low air speed. Without the contra-rotating propellers, torque reaction pulled a Griffon Seafire to the right, toward the carrier island, often with disastrous results.
The engine on display was originally fitted to an Avro Shackelton long-range reconnaissance plane which also employed the contra-rotating propeller scheme. It is identical to the Mk 58 Griffon fitted to the Mk 47 Seafire on display. Take-off power is rated at 2450 hp.