Slingsby T.7 Kirby Cadet / T.8 Kirby Tutor / T.20 / T.31
Slingsby - T.7 Kirby Cadet / T.8 Kirby Tutor / T.20 / T.31 - 1936 - Великобритания
Страна: Великобритания
Год: 1936

M.Simons The World's Vintage Sailplanes 1908-45
M.Hardy. Gliders & Sailplanes of the world

M.Simons The World's Vintage Sailplanes 1908-45


  The Kadet, Slingsby’s Type 7, was designed by John Stanley Sproule who joined the firm as what Slingsby called “a very good boy". He persuaded Slingsby to let him design a glider with better soaring ability than the Pruefling, with a span somewhat less than that of the Hols der Teufel, and a cleaner aerodynamic form. The new Kadet with its two-spar, parallel strutted wing, was test flown on 11th January, 1936. Over 20 were built. Kits were also exported for assembly overseas. The earliest models had straight-backed fuselages, the nose in front of the cockpit resembling that of the Pruefling, and the rudders were tall. There was no landing wheel. The weight, empty, was 118 kg, giving a low wing loading of 13 kg/sq m, hence the good light wind soaring ability with a pilot of average weight.
  An order was soon received from the Midland Gliding Club for a set of improved wings for their existing Kadets. Sproule laid out a tapered wing retaining the aerofoil of the Kadet since the rib jigs for the inner panels already existed. Toward the tips he changed the profile to the same reflexed form as that used on the well-known Falke. The new glider was at first known as the Taper-wing Kadet but was soon re-christened Tutor. The practice of changing wings around does not seem to have been very common. The fuselage was modified and all Kadets and Tutors thereafter had a gracefully curved rear fuselage spine. Rudders were reduced in height, and the old-fashioned nose shape was simplified. Seven Tutors were sold before the outbreak of the Second World War.
  Big developments were to follow. The Air Training Corps soon adopted the Kadet and Tutor as standard training gliders for their large, semi-military pilot training programme. Air Ministry specifications were speedily written around the two Slingsby types, and were issued. All the gliders from now on had landing wheels, were strengthened and painted in military style with dark green dope. The outer wing panels of the Tutor were simplified, giving a straight leading edge, which did not improve the appearance, but made no real difference aerodynamically. The result was a very practical, robust pair of training gliders. The names were also changed. The spelling of Kadet was evidently thought too Germanic, so it was henceforth as the Cadet Mark 1 and Cadet Mark 2 that the Kadet and Tutor were known to the ATC.
  Slingsbys built 226 Cadets and other companies another 180, under the Air Ministry contracts. Six Cadets went to Canada, one to be modified and flown in post-war years as a sailplane. One was built in the USA for study as a possible trainer for the US Army glider pilot programme. It was known there as the Kadet UT (utility) 1, and first flew at Meriden, Connecticut, in May 1943. This aircraft still survives.
  At the same time, 62 Tutors (Cadets. Mark 2) were built at Slingsby’s factory. All gliders now were fitted with the new OTTFUR safety release. Ottley Motors, a small family company in North London, built the releases and produced over 30 Cadets as a sideline.
  Post-war, Slingsby built a few more of each and, under licence, Martin Hearn Ltd sold over two dozen of both types. Altogether, 431 of Type 7 and 106 of Type 8, were produced with a few others assembled from kits or spare parts, including one in Australia. Until the early ’60s, Tutors remained the most common ’early solo' gliders in England. A two seat version, the Type 31, was produced in 1950.
  A Cadet flown by John Jeffries achieved some remarkable cross-country performances. The best, in 1960, was a distance of 260.6 km

  Technical data:
   Kadet: Span, 11.70 m. Wing area, 15.8 sq m. Aspect ratio, 8.66. Empty weight, 118 kg. Flying weight, 208 kg. Wing loading, 13.2 kg/sq m. Aerofoil, Goettingen 426.
   Cadet Mark 1: Span, 11.73 m. Wing area, 15.8 sqm. Aspect ratio, 8.71. Empty weight, 134.5 kg. Flying weight, 232.7 kg. Wing loading. 14.07 kg/sq m.
   Tutor, Cadet Mark 2: Span, 13.24 m. Wing area, 15.79 sqm. Aspect ratio, 11.1. Empty weight 159.5 kg. Flying weight. 258.5 kg. Wing loading, 16.4 kg/sq m. Best glide claimed, 1:21 at 50 km/h.

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
T.8 Kirby Tutor
The Kirby Tutor just after take-off.
Taken at High Wycombe in 1971, this photograph shows, left to right, the nose of a Weihe, the Cantilever Gull or Kirby Gull 3, the Dunstable-based Minimoa and at the far end of the line, the Kirby Tutor.
T.7 Kirby Cadet
The prototype Kadet showing the straight-backed, fuselage, with raked nost and tall rudder. The glider was finished in clear dope and varnish all over.
PD628 was an early version of the Kirby Kadet, with straight fuselage back and no wheel. Inscribed County Borough of Merthyr Wing, this example is in ATC colours.
This view of the ATC Kadet PD628 clearly shows the camouflage pattern on the glider’s surfaces.
The American Cadet UT 1, straight backed, wheelless, and still airworthy. The owner at time of publication was Tom Smith.
RAF Kirby Cadet VM637. This Mk II glider is pictured in October 1946. The wire bracing between the lift struts is clearly visible.
Two views of the Australian Kadet, imported as a kit in 1939 by members of the Gliding Club of Victoria. It first flew in January 1941 and still survives in Adelaide, but is not airworthy. Note the tall rudder, the absence of a landing wheel and the later type of fuselage.
A pre-war wheelless Kadet in flight.
T.8 Kirby Tutor
The prototype Tutor in post-war garb at Long Mynd.
Slingsby T.8 Tutor G-ALKB of the North Downs Gliding Trust, seen at Redhill devoid of its registration letters.
Built by D. C. Burgoyne as a Type 7 Cadet, BGA No 657 was brought up to Type 8 standard and is seen here bearing the civil registration G-ALTU, acquired for a short period in 1950.
A post-war Tutor built by Martin Hearn Ltd. The blue stripes of the Derbyshire & Lancashire Gliding Club may be seen on the rudder.
The "taper-wing" Kadet flown at Dunstable in 1938 by Philip Wills.
A pre-war Tutor with wing leading edge taper and no wheel.
A Tutor flying at Sutton Bank.
RAF TX Mk 2 Cadet VM634. Note the straight leading edge, the only external visible difference between the Mk 2 wing and that of the Taper-wing Kadet.
Slingsby/Osborne Twin Cadet.
John Sproule prepares to rise to the occasion during the first "air-wake" investigations aboard HMS Pretoria Castle in May 1945. At this time the Type 20 was suitably camouflaged, but it was later doped silver overall.
Picture shows the author aloft in the Slingsby Type 20 over HMS Illustrious on October 19, 1949, during the second series of experiments. The first tests had taken place over four years earlier.
The T.20 well clear and ready to rise.
During the 1949 trials, with the enormous fixed flaps in evidence.
Manhandled to a touchdown.
Lt Curry, RN, disappears below deck level, the T.20's wing tip scraping down the side of Illustrious as it descends into the sea on its last flight. The radio mast in which the tow cable became tangled can be seen immediately in front of the glider.
The Slingsby T.31 has a new lease of life note that it has become vintage. Although its performance as a school glider was something of a joke, the care taken by new owners to remove old paint and improve the finish enables the T.31s to stay up much better.
Slingsby Type 7 Kirby Kadet (Cadet)
Slingsby Type 8 Kirby Tutor
Kadet and Tutor