Slingsby T-7 Kirby Cadet
This single-seat intermediate trainer was originally designed by John S. Sproule 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.
It 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. Early examples had a rubber shock absorbed skid for takeoff and landing, but later versions had a modified nose, a less tall rudder and a fixed main wheel and a tailskid. 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.
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. The Royal Air Force air cadet training program eventually acquired 376, known as the Kirby Cadet T.X. Mk. 1.
During World War II, Total production by Slingsby and subcontractors (including Ottley Motors Ltd., a batch of 30) amounted to around 430, with some kits being supplied in addition. Plans were made available for license building.
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.
By the early 1950s most Cadet TX Mk 1s had been converted to Tutor standard (the RAF Kirby T8 Cadet TX Mk 2) by fitting the Tutor's longer span (13.24 m / 43.4 ft) tapered wings. This in turn evolved into the T.31 Tandem Tutor (RAF Kirby Cadet T.X. Mk. 3) two-place trainer. Spare T. 7 Kirby Cadet TX Mk 1 wings were used to produce the Slingsby T38 Grasshopper TX Mk 1 post war, 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.
Cadet TX Mkl
Wing span: 11.73 m / 38 ft 6 in
Wing area: 15.8 sq.m / 170 sq.ft
Length:20 ft 10.5 in
Empty Weight: 134 kg / 295 lb
Payload: 218 lb / 99 kg
Gross Weight: 513 lb / 233 kg
Wing Load: 3.02 lb/sq.ft / 14.75 kg/sq.m
Aspect ratio: 8.67
L/DMax: 14 @ 48 kph / 26 kt / 30 mph
Best glide ratio:16:1
Airfoil: Go 426
MinSink: 1.07 m/s / 3.5 fps / 2.07 kt at 32 mph
No. of Seats: 1