Bristol Bagshot

The Bristol Bagshot, also known as the Type 95 was a prototype for a heavily-armed British fighter of the 1920s built by the Bristol Aeroplane Company.

Development
The Bristol type 95 Bagshot was built to Air Ministry Specification F.4/24 in December 1924. This called for a large twin-engined fighter aircraft with a crew of pilot and two gunners, a maximum speed of 125 mph and a landing speed of 50 mph. Initially the details of the required armament were not specified. Frank Barnwell's design to meet this requirement, the Bagshot, was a high wing all-metal monoplane with an unusual triangular-section fabric-covered steel-tube fuselage with two upper longerons and a single lower member. The pilot sat in line with the wing's leading edge, with one gun position in the nose and another just behind the wing. The two-spar wing had a steel primary structure and duralumin nose ribs and end-members, and was a semi-cantilever, being braced by a pair of diagonal struts on each side. The legs of the fixed undercarriage met the wing at the same place as the struts and had an axle fairing of aerofoil section, contributing some lift. Power was provided by two wing-mounted 450 hp Bristol Jupiter VI engines.

In September 1925 the Air Ministry amended the specification, calling for supercharged engines, increased fuel load and a higher top speed at altitude. Barnwell attended a design conference to discuss these new demands and was told that the purpose of the aircraft was to carry a pair of Coventry Ordnance Works 37mm (1.460 in) cannon, generally called COW guns.

When he subsequently received full details of the required equipment, calling for two Lewis guns in addition to the main armament, Barnwell realised that the aircraft would be overweight and have a landing speed of 57 mph, and suggested making an alternative fuselage of rolled steel strip in order to save weight. If load testing of this proved unsatisfactory, he recommended abandoning the project as a waste of time. However, the Air Ministry declined to cancel the contract and the Bagshot was completed, being provisionally accepted by the Air Ministry on 12 May 1927 and being assigned the number J7767.

Operational history
The Bagshot was first flown without any armament at Filton on 15 July 1927 by Cyril Uwins, Bristol's chief test pilot. This first flight was short: 'Always a bad sign' remarks Archibald Russell (later Sir Archibald), who at that time was working in the stress calculations office at Filton. Uwins reported that control in the roll axis was poor. A second flight, during which Uwins pushed the speed up to 100 mph, revealed that the problem became worse as the speed increased. Uwins was unable to observe the wing's behaviour (He had a damaged neck thanks to an aircraft accident). It was decided that the aircraft was safe enough to carry an observer if the speed was kept down, and Russell, who had recently been working on measuring the deflection of the aircraft's wing spars under load, was given the job. The rear gun position gave an excellent view of the wing. Uwins and Russell agreed a simple system of hand signals in order to communicate. By the time the aircraft reached the agreed speed and height for the trials Russell was already very concerned. But although the 'writhing movements' of the wing were 'large and alarming' he had no signal to tell Uwins that enough was enough, and so the whole planned flight program was flown. It was concluded that control reversal resulting from twisting of the wing when the ailerons were applied was the cause of the problems. It was not feasible to modify the Bagshot's wing so as to achieve the necessary stiffness, so it was grounded and shortly afterwards broken up.