The Air Training Corp more commonly known as the ATC or Air Cadets, is a youth organization for 13 to 18 year olds, which is supported and funded by the Royal Air Force (RAF). The aims of the ATC are the same today as they were in 1941 when they were first formed:

"To promote and encourage among young men and women a practical interest in aviation and the Royal Air Force; it seeks to provide training that will be useful in the services and civilian life. It fosters the spirit of adventure and to develop the qualities of good leadership and citizenship".

 

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Slingsby Type-21 Glider (not modeled):

The prototype made its first flight in September 1950 and was followed by some 200 production machines. Most were delivered to the RAF Air Training Corps on behalf of the Air Cadets, providing eager young men a reliable mount to conquer the skies.

The Type 21 prototype, with a span of 50 ft was rejected by the ATC at first and was saved only when bought by the London Gliding Club. It was soon found it to be extremely useful and the club ordered another, with suggested improvements. Slingsby lengthened the wings and improved the fuselage. The new two-seater was demonstrated at the British National Competitions in 1947 and attracted orders. The T - 21B entered production. It became the standard training sailplane for British civilian gliding clubs and remained so until well into the 1960s. The ATC had second thoughts and also ordered the type, giving it the name 'Sedbergh'.

The T -21 was in most respects an enlarged Grunau Baby. The two seats were side by side in the open cockpit. Instructors generally preferred this arrangement because it enabled them to converse normally with the student and observe facial expressions. That there was some inescapable drag penalty hardly mattered in a trainer. The small windscreens were very effective in deflecting the airflow away from the pilots' faces. If the airspeed was not well controlled this became obvious immediately in the cockpit.

The fuselage aft of the wing was a triangulated timber frame covered in fabric except underneath where plywood skin was used to protect against damage on rough ground. The wing, like the Grunau Baby, had a single main spar, with a single strut. The leading edge was the usual kind of plywood skinned 'D-sectioned' torsion tube with fabric covering behind. Spoilers were fitted on the upper side. These, though not very effective, were powerful enough for a pupil to sense the difference when they were opened or closed.

For reasons of balance the seats had to be set back under the leading edge of the wing. The view from the cockpit upwards and into a banked turn was limited, which was the only important disadvantage of the sailplane. Since the wing was mounted high on a narrow pylon, it was easy to look sideways and aft under the wing, so despite the wing overhead, in practice the all round vision was acceptable.

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Slingsby T.31 Tandem Tutor I (The featured model)

When Slingsby introduced the Type 31 it was called the Tandem Tutor and it was perfect for training flights by pupils who had progressed to the Kirby Kadet and were ready to move on. The Tutor, or Cadet Mark 2, was built in quantity for the ATC and more were produced after 1946 for civilian use. In 1949 although the T - 21 was already becoming accepted as an excellent trainer, some clubs, particularly where the landing field was relatively rough, required a robust two seater with better performance and handling like the Tutor.

Some Tandem Tutors were modified into motor gliders, substituting the front seat for a VW or similar power plant. For ease of ground handling, The T.31 gained a narrow undercarriage replacing the single wheel. It had strengthened wings and some additional bracing of the struts. To develop a two seat glider from this involved very little work, requiring only that a front cockpit should be spliced onto the fuselage instead of engine bearers. To fit the engine in the nose the fuselage had been widened. This made room for the rear pilot's feet and rudder pedals to be placed on either side of the front seat.

The Tandem Tutor was tested by the BGA and came on the market from 1951. There were exports to many countries of complete aircraft and kits of parts. The Air training Corps took 131 and named them the Cadet Mark 3.

The T-31 Tutor has a completely wooden structure, the fuselage, tailplane and the rear part of the wing being fabric covered. As a training glider, the T.31 is flown either from the front seat by the student or from the rear seat by the instructor- full controls and instrumentation being provided for both occupants. More than 200 T-31s were built. Some are still flying as vintage gliders.

Two good photos of the Slingsby tandem configuration cockpit

These are a couple of the models Guido made while working out the Slingsby Tutor model. Note the WWII control tower he added for effects

The Slingsby Tutor nose and skid details

` The Slingsby Tutor wing struts and tailplane

 

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Specifications for the Slingsby T-31 Tandem Tutor

Length: 23 ft 3.5 in Wingspan: 43 ft 3.5 in Wing area: 170.1 ft² Aspect ratio: 11.1 Wing profile: Göttingen 426 Empty weight: 388 lb Gross weight: 829 lb Performance Maximum speed: 80.8 mph Stall speed: 38 mph Maximum glide ratio: 18.5 @ 41.6 mph Rate of sink: 206.4 ft/min

Here's Guido Van Roy, Belgium, the designer of this Slingsby Tutor model.