|
|
The Blackburn F.3 (F.7/30) was an unusual looking biplane fighter designed to get the best performance out of the Rolls-Royce Goshawk engine, but which only reached the prototype stage.
Air Ministry Specification F.7/30 called for a new single seat day and night interceptor, to replace the Gloster Gauntlet. The new aircraft was to have a top speed of at least 250mph, better range, manoeuvrability, rate of climb and service ceiling that existing fighters, be armed with four synchronized Vickers guns and carry two way radio and night flying equipment. Low wing loading and a field of view free of exhaust glare was required for the night fighter role. The preferred engine was the new Rolls-Royce Goshawk.
The specification attracted a great deal of attention, with Supermarine, Westland and Blackburn all getting contracts to produce a prototype and Bristol and Hawker both producing private venture entries.
The Supermarine Type 224 was an inverted gull wing monoplane, with fixed undercarriage in large spats attached to the low point of the wings. This aircraft failed to achieve the speed or rate of climb requirements. However some of the work that went into this aircraft helped with the development of the Spitfire.
The Westland F.7/30 (or PV.4) was a biplane with a gull wing upper wing and the engine positioned over the centre section of the lower wing and the pilot in front of the engine. It was even slower than the Type 224.
The Bristol Type 123 was a compact biplane with some unusual control features, but it proved to be rather unstable in flight and development was abandoned as this problem couldn’t be fixed.
The Hawker PV.3 was a larger version of the Hawker Fury, and was probably the best of the F.7/30 designs, but it arrived too late.
Blackburn produced the most unusual looking design. The F.3 was a biplane, but visually looked like a mid-wing monoplane sitting on top of a second wing. The fuselage was raised from its normal position between the wings to a new position high in the aircraft, with the upper wing half way up the fuselage. The nose dropped down sharply from the cockpit, giving the pilot excellent views forward and above. A large honeycomb steam condensing radiator was positioned below the main fuselage, connecting to the lower wing. The smaller lower wing was connected to the upper wing by N struts towards the outer ends, as well as the radiator and short struts to the fuselage. Two machine guns were carried just in front of the upper wing roots, and two at the top of the condenser fairing.
The F.3 made its first taxiing trials at Brough on 20 July 1934. Ground handling trials began on 17 August. These revealed that the aircraft was difficult to handle on the ground because of its short fuselage and high centre of gravity. Attempts to fix this problem made little difference. On 5 September cracks and dents in the fuselage skin were found. The F.3 wasn’t ready to be delivered in time for the competitive trials, and so the Air Ministry withdrew the prototype order. The F.3 never flew and in July 1936 went to the Electrical and Wireless School at Halton for use as an instructional airframe.
The biggest problem with all five of the designs was the Goshawk engine. It was based on the very successful water cooled Rolls Royce Kestrel, which was used in many RAF aircraft of the late 1920s and early 1930s. The Goshawk used a steam cooling system, which allowed the cooling liquid to evaporate, increasing the amount of heat it could take from the engine. However the steam then had to be cooled and turned back into water before it could be used again, requiring large condensing radiators in the wing. Only twenty Goshawk engines were built. It suffered from problems with coolant leaks and with the coolant pumps, and didn’t produce as much power as expected. It was also realised that the large condensing radiators would be very vulnerable to battle damage, making the engine unsuited for use in a fighter. As a result the project was cancelled, and none of the aircraft submitted for F.7/30 entered production. Instead the contract went to the Gloster Gladiator, which used the more reliable Bristol Mercury engine, and fulfilled most of the requirements of the specification.
Book 309
Engine: Rolls-Royce Goshawk III
Power: 660hp
Crew:
Span: 36ft 10.75in
Length: 27ft 0in
Height: 10ft 0in
Empty weight: 2,500lb
Maximum take-off weight:
Max speed: 190mph
Climb Rate:
Service ceiling:
Endurance:
Armament:
Bomb load: