M.Hardy. Gliders & Sailplanes of the world

Slingsby Kirby Cadet

  Well known as the glider on which hundreds of Air Training Corps cadets received their training, this single-seat intermediate trainer was originally designed in 1935 as a soarable version of the Slingsby T3 or Nacelled Primary glider, and was at first known as the T7 Kirby Kadet. It first flew in prototype form at Sutton Bank on 11 January 1936, and was of conventional wood and fabric construction, with a high-set, braced, two-spar constant-chord wing that was, in fact, interchangeable with that of the later T8 Tutor; no flaps or air brakes were fitted, and the ailerons were fabric-covered. The plywood-skinned wing was mounted on a built-up centre portion of the fuselage, in front of which the pilot sat in an open cockpit, and there was no monowheel, the landing gear consisting of a nose skid and a tailskid. Only 22 Kadets had been built when the war put a stop to production, the price of a new one being £93 in 1939, which had risen to £325 by 1948, but the type was put back into production with an Air Ministry order for 200 for use by the ATC, the first aircraft from this order, later to be known as Cadet TX Mk 1s, being built in 1943; the ATC variant differed slightly from the prewar civil Kadet in having reduced rudder height and a monowheel in the fuselage as well as the nose skid. The ATC's predecessor, the Air Defence Cadet Corps, had given its cadets some instruction at British gliding clubs before the war, but this stopped when war broke out, and it was not until 1942 that the first ATC gliding school was opened at Kirbymoorside, Yorkshire, where the Slingsby works were located, and an instructors' course was started. By December 1945 the ATC had 84 gliding schools with over 600 Service and civilian instructors, and about 4,500 cadets had received some gliding instruction, as well as instruction in winch-launching, and an equal number had reached the top proficiency stage of their training. Altogether 226 Cadets were built during the war by Slingsby and three other subcontractors, of which Martin Hearn Ltd of Hooton Park, Cheshire, was the most important; this firm also built 27 of the postwar production for gliding clubs, which brought the total built since 1936 to 431. The Cadet's Gottingen 426 wing section gave it gentle stalling characteristics and good lift at low speeds and this, allied to a simple design making for ease of repair as well as manufacture, made it an excellent trainer. By the early 1950s most Cadet TX Mk 1 s had been converted to Tutor standard (the T8 Cadet TX Mk 2) by fitting the Tutor's longer span wings, and spare Cadet TX Mk 1 wings were used to produce the Slingsby T38 Grasshopper TX Mk 1, which was a version of the SG 38 primary glider with a simplified open-framework fuselage, modified tail unit and the surplus Cadet wings; production began in 1952 and 115 Grasshoppers were built.


Data: Cadet TX Mk 1
Span: 38 ft 6 in
Length: 20 ft 10 1/2 in
Wing area: 170 sqft
Aspect ratio: 8.67
Empty weight: 295 lb
Max weight: 513 lb
Min sinking speed: 3.5 ft/sec at 32 mph
Best glide ratio: 16:1



Slingsby Kirby Tutor

  The T8 Tutor single-seater introduced in 1937 was an improved version of the Kirby Kadet with a new two-spar wing of increased span (43ft 3 3/4 in) and tapered outer wing panels married to the same wooden fuselage and wooden tail unit with braced tailplane as the Kadet's. At the same time a differential mechanism was introduced into the aileron control circuit. This wing was, in fact, capable of being fitted to the Cadet TX Mk 1, most of which, by the early 1950s, had been converted to Tutor standard as the T8 Cadet TX Mk 2 by the fitting of this wing. The Tutor prototype first flew in July 1937 and seven examples had been built by the outbreak of war; it re-entered production after the Cadet to meet the demands for an ATC trainer, and 62 more were built in the war as the Cadet TX Mk 2. Total Tutor production was 106, and the price had risen from £99 10s (£99.50) in 1939 to £360 ex-works in 1948. A new two-seater version for teaching the initial stages of flying, and suitable for the arduous circuits and bumps of training, was the T31 Tandem Tutor, which first flew in prototype form in September 1950. This was selected as a standard ATC trainer, being known as the Cadet TX Mk 3 by the RAF, and altogether 131 were built for the ATC and 69 for gliding clubs and other civil customers; 14 more were built from Slingsby-supplied kits and a number of Tandem Tutors were also built from Government surplus spares. The Tandem Tutor can be flown either dual or solo, and differs from the single-seat Tutor chiefly in having the forward fuselage lengthened to accommodate the second cockpit. An extra V-strut over the rear cockpit windscreen supports the wing leading edge, and wing spoilers are usually fitted in the upper surfaces, although some Tandem Tutors do not have them, and flaps are not fitted. The forward fuselage is plywood-skinned and the rear fuselage is fabric-covered; the pilots have full dual controls. Landing gear is basically the same as the Cadet's with a monowheel, a skid under the forward fuselage and a tailskid.
  A powered version of the Tutor was undertaken, somewhat against his wishes, by Mr Fred Slingsby, and this, the T29 Motor Tutor, featured a new fuselage with a fixed, divided-axle type undercarriage and tailwheel married to the standard Tutor wings and tail unit. It first flew, as the T29A with a 25hp Scott Flying Squirrel engine, in December 1947 but this first prototype was underpowered, and the second prototype, the T29B which first flew in June 1948, had a 40hp Aeronca JAP two-cylinder, horizontally-opposed air-cooled engine; a single 9.5 Imp gallon fuel tank was installed. It was intended that the Motor Tutor should be sold in kit form for assembly by Ultra-Light Aircraft Association groups but when, after protracted deliberations, the ARB at last granted the Motor Tutor a C of A it was not for training and, since this role had been the main reason for developing the type in the first place, further work on the Motor Tutor ceased and an initial order for six was cancelled.


Data: T31 Tandem Tutor
Span: 43 ft 3 3/4 in
Length: 23 ft 3 3/4 in
Wing area: 170 sqft
Aspect ratio: 11.1
Empty weight: 388 lb
Max weight: 830 lb
Max speed: 81 mph
Min sinking speed: 3.44 ft/sec at 42 mph
Best glide ratio: 18.5:1 at 45.5 mph



Slingsby/Osbourn Twin Cadet

  This powered conversion of a T8 Tutor was made by E. W. Osbourn at Cranfield, Bedfordshire, in 1969 and was known as the Twin Cadet Mk 1. It was fitted with two 197cc Villiers 9E single-cylinder two-stroke engines mounted on the wing bracing struts and driving two small propellers just behind the pilot's head. The prototype, G-AXMB (ex-VM590 and BGA 805) first flew with power on 20 September 1969. and received its Authorisation to Fly on 2 July 1970. It was later re-engined with a single 500cc Triumph T100 motorcycle engine mounted in the nose and first flew in this form as the Cadet Mk 2 at Cranfield on 22 January 1972, receiving its Authorisation to Fly on 6 June that year.
  Another motorised version of the basic Cadet/Tutor airframe was the Slingsby/Martin Motor Cadet Mk 3, which was a T31 Tandem Tutor acquired from the Dorset Gliding Club in 1970 and converted by P. J. Martin and D. R. Wilkinson at Twinwood Farm aerodrome, Bedfordshire, to have a 1,600cc Volkswagen engine in the nose. It was now a single-seater ultra-light, the front seat being replaced by a 6 1/2 gallon fuel tank, and a Luton Minor's undercarriage was fitted to give airscrew clearance. Registered G-AYAN and named 'Thermal Hopper', the sole Cadet Mk 3 received its Authorisation to Fly on 15 January 1971.


Data: Twin Cadet Mk 1
Span: 38 ft 6 in
Length: 20 ft 10 1/2 in
Tare weight: 455 lb
All-up weight: 657 lb
Max speed: 60 mph (power on)
Cruising speed: 40 mph (power on)
Range: 100 miles