World War II Database

Contributor: Alan Chanter

ww2dbaseThe Westland P.9 Whirlwind was designed in 1936 by W.E.W. Petters (see note 1) to the requirements of Air Ministry specification F.37/35 for a high-performance fighter, armed with four cannon. It would become the Royal Air Force's first twin-engined single-seat fighter and the first such aircraft to be used in numbers by any of the belligerent powers. Of orthodox all metal stressed-skin construction, the Whirlwind introduced several design innovations later to be widely adopted. It had an extremely slim fuselage (the cross section of which was less than that of the engine nacelles), and the four Hispano cannon were closely grouped in the fuselage nose to give a dense concentration of fire. The all-round vision cockpit was an advanced feature, and the coolant radiators were ducted within the centre section of the wing, In addition the Whirlwind incorporated Fowler-type flaps which extended from aileron to aileron.

ww2dbaseA contract for two prototypes (L6844 and L6845) was placed in February 1937, with the first of these flying on the 11th October 1938. An initial production order for 200 machines was placed in January 1939 (followed by a second order for a similar number), with deliveries to fighter squadrons being scheduled to commence during the following September. Unfortunately deliveries the first Peregrine engines (in essence a modernised version of the classic Kestrel) did not reach Westland until January 1940, and, in consequence, the first Whirlwinds did not enter service until June, 1940.

ww2dbaseTeething and delivery problems with the Peregrine engines (See Note 2) coupled with a number of flying accidents and a high landing-speed which restricted the number of airfields from which it could operate, resulted in production being terminated in January 1942 after the completion of just 112 production aircraft. These aircraft equipped just two squadrons of the RAF (No.263 Squadron from June 1940, and No.137 Squadron from November 1941. Both would re-equip with Typhoons in November 1943.

ww2dbaseNotes:
1. W.E.W. Petters would later be the chief designer of the post-war English Electric Canberra.
2. Rolls-Royce being, at that time, more concerned with improving and maximising production of the important Merlin engine.

SPECIFICATIONS

Whirlwind I

Machinery	Two Rolls-Royce Peregrine 1 liquid-cooled V-12 engines rated at 885hp each
Armament	4x20mm Hispano Mk.I cannon, 2x250lb or 2x500lb bombs
Crew	1
Span	13.72 m
Length	9.83 m
Height	3.20 m
Wing Area	23.22 m²
Weight, Empty	3,969 kg
Weight, Loaded	4,697 kg
Weight, Maximum	5,166 kg
Speed, Maximum	579 km/h
Service Ceiling	9,145 m
Range, Normal	1,287 km

Photographs

Visitor Submitted Comments

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1.  Alan Chanter says:
10 Oct 2007 01:56:36 AM

No.263 Squadron R.A.F. undertook a number of light day bomber escort duties with their Whirlwind fighters. The best known of the operations undertaken being the escort of six Blenheim squadrons as far as Antwerp on August 12, 1941. In the summer of 1942, the Whirlwinds of both squadrons were fitted with racks for two 250-lb or 500-lb bombs (redesignated Whirlwind IA), These subsequently undertook low-level cross-channel attacks on locomotives, bridges, shipping, harbour installatons, and other targets until 1943 when both Squadrons re-equipped with Typhoons.

2.  Alan Chanter says:
15 Oct 2007 04:20:01 AM

One Whirlwind(P6972)underwent night fighting trials in 1940 with No.25 Squadron and at one period the first prototype (L6844) was fitted with twelve 0.303-in Browning guns. Another Whirlwind was fitted experimentally with a single 37-mm cannon.

3.  Alan Chanter says:
27 Oct 2007 03:37:45 AM

For a twin-engined aircraft the Whirlwind was highly manouvrable and its handling characteristics were frequently referred to as delightful. Also its performance at low altitude was superior to that of many contemporary single engined fighters. Unfortunately, rather poor maintenance characteristics and continuous teething troubles suffered by its Peregrine geared and supercharged engines (which powered no other service type), coupled with serious delays in engine deliveries conspired to restrict the Whirlwinds career to only two R.A.F. squadrons.

6.  Alan Chanter says:
14 Oct 2022 11:19:13 AM

No. 485 Squadron RNZAF was a Spitfire squadron formed in March 1941 under Article XV of the Empire Air Training Plan.