Rolls-Royce Goshawk / PVG
The engine first ran in 1933 and was first announced in 1934, and originally known as the P.V.G., this modified Kestrel paved the way for the development of the Merlin and was designed to be evaporatively cooled. The Goshawk was developed from the Kestrel IV prototype engine, to use evaporative (also known as "steam") cooling. Rather than keep the cooling liquid below its boiling point in the cooling system, the coolant was allowed to boil; boiling taking more heat from the engine and less coolant was needed. Instead of a radiator to take the heat from the coolant, a condensor was required to turn the vapour back to liquid. These had to be much larger than radiators and added drag to the aircraft design.
Bore and stroke were the same as for the Kestrel, i.e., 127 mm x 140 mm.
Twenty engines were built and they flew only in prototypes as a few manufacturer's private ventures and "one offs".
Goshawks I, II and III were fully supercharged and gave 600 h.p. at 2,600 r.p.m. at 12,000 ft, and 650 h.p. at 15,000 ft. The weight was 975 lb, and the three marks had reduction-gear ratios, respectively, of 0.632,0.533 and 0.477. Goshawks VI, VII and VIII were medium-supercharged units rated at 660 h.p. (490 kW) at 2,600 r.p.rn. at 6,000 ft, and geared-successively as the I, II and III.
Problems with coolant leaks, coolant pumping and the realisation that large wing mounted radiators would be vulnerable to combat damage caused the project to be cancelled although lessons had been learned and were put into development of the later Merlin.
Only 20 Goshawks were built, but they were fitted in the Blackburn R7/30, Bristol R7/30, Gloster S.15/33, Hawker P.V.3, and Short R.24/31. The Goshawk was the power unit specified for the twin engined Short Knuckleduster flying boat (K3574) to Specification R24/31 and "preferred" for submissions to Air Ministry specification F7/30 for a fighter aircraft. Goshawks were used by all three officially sponsored prototypes, the Supermarine Type 224 (K2890), the Westland F.7/30 (K2891) and the Blackburn F3 (K2892), which only taxied with the Goshawk fitted and did not fly), in addition to two private venture entrants, the Bristol Type 123 and the Hawker P.V.3.
The Goshawk also powered Hawker's privately developed "High Speed Fury Mk 2" (K3586) and "Intermediate Fury" 2" (the latter Hawker's own development aircraft and "hack" serial G-ABSE) and the Westland Pterodactyl V (K2770) and was installed for trials in the Gloster TSR.38 (S1705), and the first Gloster Gnatsnapper prototype (N227).