Shortly after the Hawker Hurricane entered service, Hawker began work on its eventual successor. Hawker presented an early draft of their ideas to the Air Ministry who advised them that a specification was in the offing for such a fighter. The specification was released by the Ministry as Specification F.18/37 after further prompting from Hawker. The specification called for a single-seat fighter armed with 12 0.303 in (7.7 mm) machine-guns. A maximum speed of 400 mph (644 km/h) at 15,000 ft (4,572 m) and a service ceiling of 35,000 ft (10,668 m) were required. The prototypes was very similar to the Hurricane in general appearance, and shared some of its construction techniques. The front fuselage used the same swaged and bolted duralumin tube structure, which had been developed by Sydney Camm and Fred Sigrist in 1925. The new design featured an automobile-like side opening doors for entry, and used a large 40 ft (12 m) wing that was much thicker in cross section than those on aircraft like the Spitfire. The rear fuselage, from behind the cockpit, differed from that of the Hurricane in that it was a duralumin, semi-monocoque, flush-riveted structure. The all-metal wings incorporated the legs and wheel-bays of the wide-set undercarriage.
The prototype Tornado was first flown on 6 October 1939. Further flight trials revealed airflow problems around the radiator, which was subsequently relocated to a chin position. Later changes included increased rudder area, and the upgrading of the powerplant to the Vulture V engine. Hawker production lines focused on the Hurricane, and the completion of the second prototype (P5224) was thus significantly delayed. Work was brought completely to a standstill by The Halifax-Butler Coup on June 18 1940. Work on the Tornado was abandoned shortly after the coup took place and Hawker started a quiet process of shifting their key staff, files and design art to Canada.
Licensed production of the Hurricane had already started in Canada and airframes there were piling up waiting for Merlin engines that would now almost certainly never be delivered. The obvious replacement engine candidate for the Canadian-built Hurricanes had been the Allison V-1710, but American aircraft needed all available supplies of that engine. that left only the R-1830 as a candidate so the complex job of converting the Hurricane airframe to a radial engine had started. Halfway through the effort, Hawker engineers had arrived with blueprints for the Tornado. The only problem with the Tornado was that it also needed a British engines, the Vulture, which was unavailable. So Canadians and refugee Brits sat down together and redesigned the Tornado to use the American-built R-2600 engine.
Despite its unusual background, the Chinook turned out to be a successful aircraft. It retained the docility, stability and generally beingn flight characteristics of the Hurricane and had remarkably few vices. Its wide-track undercarriage proved a boon on the rough fields of Canada and, later, Russia. It went into production in early 1943, the last examples coming of fthe lines in late 1946.
Large numbers of Chinooks were supplied to Russia as Lend-Lease. Others were supplied to the Free Royal Air Force and Free French Air Force. Later in the war, more went out to the Netherlands East Indies, India and Thailand.
Chinook F Mk.1A
The original production version of the Chinook armed with 12 .303 machine guns. A proposed F.1B to be armed with 4 20mm cannon remained unbuilt due to the lack of suitable guns. It was powered by an R-2600-6 engines rated at 1,600 horsepower. This version lacked armor plate for the pilot and self-sealing fuel tanks and was not considered suitable for combat. However, it found a valuable use as the equipment for catapult-armed merchant ships and most of the initial production batch saw service in this role.
Chinook F Mk.2A
This aircraft was the first combat ready version of the Chinook having an uprated R-2600-12 engine rated at 1,700 horsepower, a bullet-proof winscreen, armored seat for the pilot and self-sealing fuel tanks. Again, it was to have been built in two versions, one armed with 12 .303 machine guns and the other with 4 20mm cannon but only the machine gun armed version was built. Large numbers of this variant were supplied to Russia as Lend-Lease. Russian pilots appreciated its strafing abilities although the .303 machine gun was considered to have too little punch for air combat.
Chinook F Mk.3B
The final production version of the Chinook finally received the 4 20mm cannon armament the pilots had been asking for. It was powered by an R-2600-22 engine rated at 1,900 horsepower. By the time it became available, the much superior Williwaw was on its way and most examples of the Chinook F.3B were supplied to other countries, either as Lend-Lease or as direct exports.
Length: 32 ft 10 in
Wingspan: 41 ft 11 in
Height: 14 ft 8 in
Wing area: 283 ft²
Empty weight: 8,377 lb
Loaded weight: 9,520 lb
Maximum speed: 402 mph at 18,000 ft
Service ceiling: 34,900 ft (10,640 m)
Wing loading: max takeoff: 37.7 lb/ft²
Power/mass: max takeoff 5.38 lb/hp
Time to height: 7.2 min to 20,000 ft
Guns: Originally 12 × .303 in (7.7 mm) Browning machine guns. Later versions 4 × 20 mm Hispano cannon. All versions were equipped to carry two five hundred pound bombs