Welkin (Janes All The Worlds) a high altitude fighter designed to combat possible stratospheric raids by the Luftwaffe over England at heights beyond the range of existing fighters. The entire emphasis was on attaining the highest possible ceiling, maximum possible speed and carry four 20mm cannon. Aircraft seriously handicapped by compressibility problems exacerbated by its long but thick wings. Production ended with 101 airframes, of which final 26 delivered less engines, and all but a handful going to MUs for ultimate disposal. Did not see operational service. Two models of a two seat version were built.
(Allied Aircraft Piston Engines by Graham White) The Peregrine was a promising engine by WWII standards based on the Kestrel (same bore, stroke, capacity) and was often described as a “Merlinized Kestrel” because of Merlin features incorporated into its design. Even with a high specific power of 885 HP it was inadequate for the demands of WWII combat. Numerous problems during its brief service life earned it the unflattering nickname “Pesky Peregrine”. Overheating seemed to be the main problem due to the nature of the installation in the Whirlwind. In certain flap configurations the airflow through the leading edge radiators (similar to Mosquito) was reduced. Innovations abounded in the Whirlwind such as leading edge radiators, bubble canopy and T tail. (Beags – I have faint recollection that it also had fuel tank inerting via the exhaust, the exhaust itself being dumped via the typical Merlin shrouded system.)
The Vulture was a totally new design, although often described as a doubled up Kestrel or Peregrine due to all three having the same bore and stroke.
(Bill Gunston) As WWII became increasingly likely the Royal Air Force determined that it was deficient in a powerfully armed aircraft that could undertake long-range escort duties and night-fighter operations. A requirement (F.37/35) not all that different from the German's Messerschmitt Bf-110. From a specification drawn up in 1937 came the Westland Whirlwind, a heavily armed escort fighter. It had some teething problems related to the Rolls Royce Peregrine engine (an unhappy outgrowth of the reliable Kestrel) and the fact that it's landing speed was 80 mph, which meant that it could not use the standard (short) grass field of a British aerodrome. The type was a stable and pleasant aircraft to fly and had a formidable amount of firepower for the time (four 20-mm cannons). It showed some promise in combat, however, like its German counterpart it was not agile enough to successfully combat enemy fighters. The speed quickly garnered it the nick-name Crikey, meaning "my god!" or more accurately "Christ's keys".
After some deliberation the RAF purchased only 112 and equipped only two squadrons, No.s 137 and 263, with the aircraft. After initial use as an escort fighter, it was relegated to convoy patrols and eventually as a "Whirlybomber" flying low-level "rhubarbs" with bombs and cannons against targets of opportunity in France. It was phased out of use in 1942 as better aircraft (primarily the Typhoon and Beaufighter) were being put into service that would outperform it at a lower cost. The Typhoon could carry the same armament with a single engine, and the Beaufighter was even more powerfully armed and used Bristol radial engines that were in greater supply. Also, Rolls Royce dropped the Peregine engine to focus on producing the Merlin.