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Aviation History
1939
1939 - 0367.PDF
FEBRUARY 9, 1939 FLIGHT. 139 SERVICE AVIATION Royal Air Force and Official An nouncements : Fleet Air Arm Neivs : Military Aviation Abroad The Boulton Paul Defiant two-seater fighter, described below. New Two-seater Fighters OFFICIAL regulations are such that news of important de velopments is often withheld for so long that members of the public who interest themselves in the equipment of our Air Force become apprehensive. By way of example, a num ber of letters have been received in this office during the past year or two enquiring as to the progress in the design of two- seater fighters, emphasising that since 1930 the Hawker Demon has remained our standard aircraft in that category. Only within the last few days has it become permissible to refer to and illustrate our new standard type and another for midable machine in the same class. A number of R.A.F. squadrons will shortly be equipped with the Boulton Paul Defiant low-wing monoplane with Rolls- Royce Merlin engine. The Defiant is entirely of metal con struction, light alloy being the chief material employed. Wings and fuselage have stressed-skin covering, with flush riveting, presenting an exceptionally smooth surface. A slight taper is given to the centre section, the outer wing panels, which have a pronounced dihedral angle, being more heavily tapered and having rounded tips. Split flaps are fitted to the inner portions of the wings and Frise ailerons of high aspect ratio are placed outboard of these. The elevators and rudder are partly horn balanced and have small trimming tabs. The oleo pneumatic undercarriage retracts inwardly into the centre section and is provided with appropriate panels for completing the under-surface of the wing. The military interest lies chiefly in the concentration of all the armament in a Boulton Paul power-driven gun turret, faired as completely as possible compatible with the provision of a good field of fire. The actual number of guns installed is still undisclosed. It is to be assumed that the Defiant will be used chiefly for attacking formations of enemy bombers, probably by flying slightly ahead of and below the raiders, who are likely to be comparatively poorly armed in the nose. This form of attack has been demonstrated in public by Demons. The actual mark of Merlin fitted may not be specified. Assuming that it is a Merlin II as installed in the Hurricane and Spitfire single-seaters it may be guessed that the speed of the Defiant is of the order of 300 m.p.h., considering the drag of the turret and the fact that the dimensions are little larger than those of the Hurricane. Fitted with the Merlin II or X fully supercharged engine, the Defiant should certainly be faster than any comparable two-seater ordered for any foreign Air Force. The use of a Merlin R.M. 2 S.M. two-speed supercharged engine operating on 100-octane fuel (1,145 n-P- at 16,750ft.) would, of course, improve the performance very considerably. The De Havilland three-bladed variable-pitch airscrew is fitted with a spinner which should give an exceptionally clean entry. The oil cooler is cowled in under the rear of the engine, while the radiator for the coolant is placed under the fuselage, approximately between the pilot's cockpit and the rear gun ner's position. The exhausts are of the new "ejector" type. Main dimensions of the Defiant are: Span, 39ft. 6in.; length, 30 ft.; height, 12ft.; wing area, 250 sq. ft. The Hotsptir Hotspur is the name of the second two-seater fighter, pre liminary details of which have just been released. This Hawker product is also comparatively small, the dimensions being as follows: Span, 40ft. 6in. ; length, 32ft. lo^in.; height, 10ft. nin. wing area (gross), 261.5 S<1- ft. In view of the peculiar shape of the Hotspur's turret the fairings are arranged differently from those on the Defiant. Apart from the inevitable break in this region the machine has very clean- cut lines and gives an impression of great strength, which is accentuated by the placing of the radiator fairing directly be neath the engine, as in the Henley two-seater. The wings of the Hotspur have Frise ailerons and are of stressed-skin metal construction, but the fuselage is fabric covered. It appears that the undercarriage is similar to that on the Henley. The Merlin engine has ejector-type exhausts and drives a three-bladed v.p. De Havilland airscrew. The Hawker Hotspur two-seater fighter has a turret of an unusual barrel- shaped design.
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