Slingsby T . 20 The Slingsby T . 20 was a British glider designed and built by Slingsby that first flew in 1944 . Design and development . The Type 20 was probably the least well known Slingsby product , yet it arguably had the most exciting flying life . The design started life in parallel with the larger Type 21 , as a private venture inexpensive robust two - seat training glider intended for the Air Training Corps . The aircraft borrowed design elements from several predecessors , including an enlarged wing from the T . 8 Kirby Tutor , and a fuselage , reminiscent of the early Falcons , with cabane struts in front of the rear cockpit , which sat in front of the narrow cabane structure under the centre - section , as well as an additional cockpit in the nose . Flight trials . Flying with the T . 20 began in 1944 with no reported problems , the prototype languished at Sutton Bank Gliding Club , emerging only to fly the occasional illegal soaring flight , the pilots that flew the T . 20 all praising its handling . No production order was forthcoming however . Preparation for carrier trials . During the intensive carrier operations of the war it had been noticed that there were many accidents as aircraft neared the ' Round - down ' ( the aft edge of the flight deck ) on their approach to ' Land - on ' . To investigate this phenomenon the Admiralty authorised a research program to establish airflow patterns over the ' Round - down ' on large Aircraft Carriers using a suitable glider towed behind a carrier using a small winch to allow the glider to climb , descend and move forwards and backwards in relation to the ' Round - down ' . John Sproule , former designer at Slingsby , was ordered to find a suitable aircraft and carry out the test flying . In 1945 Sproule visited the Slingsby works and took the prototype T . 20 away for use in the carrier trials . Carrier trials on HMS " Pretoria Castle " . The T . 20 was fitted with special instrumentation and large Zap flaps , fixed at 30° , at Wombleton aerodrome where initial trials were carried out at low altitude towed behind a car . The glider , scientists , John Sproule and winch were loaded onto HMS " Pretoria Castle " at the Clyde docks and on 29 May 1945 the T . 20 took off , tethered to a winch on the flight deck . The glider was manoeuvred around the aft end of the carrier , as she steamed along at 35 knots , until there was a sudden shift in the wind which left Sproule struggling to maintain height calling for the winch to haul him in so he could gain height . The winch engine had stalled and was reluctant to start , but just as Sproule was preparing to abandon the T . 20 in the wake of the carrier , the winch burst into life and the T . 20 climbed away allowing the shaken Sproule to land the T . 20 back on the deck . Results gathered by the instruments were of poor quality so the trials on " Pretoria Castle " were abandoned . Carrier trials on HMS " Illustrious " . After the scientists had modified their instruments , a new set of trials were authorised to take place on . Sproule and an experienced glider pilot as deputy , scientists , glider and equipment were embarked on " Illustrious " in the English Channel . Initial flights with Sproule at the controls went well , but his deputy ' s first outing ended in disaster as the pilot failed to pull back on the stick to climb away , staying close to the deck weaving from side to side till eventually the tow cable snagged a telecoms antenna and unceremoniously dumped the T . 20 into the ' Oggin ' alongside the carrier . The deputy pilot was rescued but the unfortunate T . 20 was rammed by an accompanying destroyer to ensure the wreckage sank .