History Of The Blackburn
During the early 1950s, the Soviet Navy underwent a major fleet expansion to challenge US and NATO naval supremacy, posing a serious threat with their new of SVERDLOSK-class cruisers.In response, the British Royal Navy decided to obtain a low-level carrier based attack aircraft. This aircraft was intended to penetrate the defenses of Soviet naval battle groups by streaking in at low level and high speed, then destroy them with a nuclear weapon in a "toss-bombing" attack.
The requirement was formalized as "Naval Staff Requirement Number 39 (NA.39)" in June 1952, which called for a two-seat carrier-based aircraft that could carry a nuclear weapon internally, fly at a speed of Mach 0.85 at an altitude of 60 meters (200 feet), and operate over a combat radius of at least 740 kilometers (460 miles).
Total weapons load was to be 1.8 tonnes (4,000 pounds); the length could be no more than 15.5 meters (51 feet) in stowed configuration to allow accommodation on existing carrier-deck elevators; and the maximum weight was to be no more than 20.4 tonnes (45,000 pounds). The aircraft was to have the capability of acting as a tanker.
At the time, Blackburn was building nothing more warlike than transport and cargo aircraft. Nonetheless, the company responded to the requirement with a design with the company designation "B.103", which incorporated a number of advanced features.
The requirements for aircraft payload and performance dictated twin engines. Blackburn originally considered the Armstrong Siddeley "Sapphire Sa.7" engine with 4,990 kilograms (11,000 pounds) thrust, but it proved too bulky and heavy. As an alternative, de Havilland proposed a scaled-down version of their Gyron turbojet, the "PS.43 Gyron Junior", to be known in production as the Bristol Siddeley "Gyron Junior Mark 101". The Gyron Junior was a non-afterburning engine that offered 3,630 kilograms (8,000 pounds) of thrust.
Low-level flight demands an aircraft with small wings and high wing loading to reduce bumpiness from gusts and turbulence, but carrier takeoff and landing generally demands large wings and low wing loading to ensure short takeoff, and slow landing speeds. Blackburn compromised by using a small wing that incorporated a "flap blowing" or "boundary layer control (BLC)" system.
The BLC system used a network of ducts that bled ten percent of the engine compressor flow and routed it to the leading edges of the wings and over the flaps and ailerons. It also directed engine bleed air to the underside of the high-set "tee" tail. The BLC system almost doubled lift at low airspeed, and also provided an effective de-icing system.
The B.103 was designed to be fitted with two stores pylons under each wing, for a total of four, but also had a bomb bay, which was to accommodate four 450 kilogram (1,000 pound) bombs or a single nuclear weapon. A conventional bomb bay was not regarded as suitable for high-speed low-level attack, and so the B.103 was given a rotating bomb bay door, with munitions attached to the door itself. The door could snap around rapidly, reducing aerodynamic difficulties.
The rotating bomb bay not only simplified weapons release, but made it easier to load munitions and perform servicing. The bomb bay could also in principle accommodate a reconnaissance camera pack; a 2,000 liter (528 US gallon) ferry fuel tank; a cargo container; or a pack with twin Aden 30 millimeter cannon.
However, although the other items were built, the cannon pack was not, and the aircraft would never incorporate gun armament. The cargo container would prove useful for transporting golf clubs and other essentials.
Total internal fuel capacity was 7,092 liters (1,871 US gallons). This fuel load was augmented by two underwing "slipper" tanks that were mounted over the inboard stores pylons and had a capacity of 1,136 liters (300 US gallons), as well as the ferry tank mentioned above.
The B.103 incorporated the new "area rule" aerodynamics, where abrupt changes in the cross-sectional area of the aircraft, including the wing, were to be avoided. This allows the fuselage to expand aft of the wing and results in a "coke bottle" appearance. Blackburn engineers used area-ruling to improve the design's aerodynamics, while also increasing the storage capacity of the aircraft's fuselage, giving the aircraft a distinctive set of full-bodied curves. The airframe was designed with an emphasis on strength, and the aircraft would generally be described as being "built like a brick outhouse".
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