The Grasshopper is a primary single-seater glider intended to give basic training through short ‘hops’ on airfields or school playing fields. The open framework fuselage with a seat for the pilot was a simplified version of that of the Schulgleiter SG 38. It used the wings of the Slingsby Cadet Mk I and was designed to be easily dismantled for storage. The wing being wire-braced and without flaps or air brakes. A post war surplus of the T. 7 Kirby Cadet T.X. Mk. 1’s resulted in Slingsby building the primary T. 38 Grasshopper T.X. Mk. 1 with surplus T. 7 wings and tailplanes married to a new primary open fuselage. Most Cadet TX Mk Is were converted to Tutor standard as the T8 Cadet TX Mk 2 by fitting them with the Tutor’s longer span wings, and the spare wings of the TX Mk 1s were used to produce the Grasshopper TX Mk1.

It was launched by a V shaped elastic rope pulled by teams of cadets and could also be mounted on a pivoting tripod stand to enable the effects of the controls to be demonstrated.

The Grasshopper and the virtually identical EoN Eton were used by ATC Squadrons and RAF Sections of the Combined Cadet Force from 1952 to the late 1980s and many cadets made their first, somewhat brief, solo flights in these gliders.

Production began in 1952 and altogether 115 Grasshoppers were built.

Span: 39 ft 0 in
Length: 21 ft 1.5 in
Wing area: 174 sq ft
Aspect ratio: 8.73
Empty weight: 293 lb
Max weight: 550 lb
Max speed: 80 mph

The T37 Skylark 1, first of the series, was built for a lark, according to Mr F. N. Slingsby-hence its name – and was an experimental single-seater with a three-piece laminar flow wing of 45ft span, intended to test various lateral stability devices to determine the best type of lateral control surface for use with a laminar flow aerofoil; the wing was of NACA 63-/64-series section and had very effective air brakes but no flaps. The fuselage was based on that of the T30 Prefect, with a one-piece canopy, the length being 20ft 11.5 in, and there was a main skid only plus a tailskid, no monowheel being fitted.

The first of two prototypes made its maiden flight in March 1953, and only the two Mk 1s were built partly as this version had, for that time, a very high stalling speed. But it had proved sufficiently promising to be developed into the T37B (later T41) Skylark 2.

Both of the single-seat Skylark 1 built were still flying in 1977.

The Sky first flew in prototype form in September 1950 and was designed for the 1951 British National Championships, in which it came first and second, at the request of the newly-formed Royal Air Force Gliding and Soaring Association, who wanted a contest sailplane with a better performance than that of the well-known DFS Weihe. The Sky was basically an 18m span version of the 15m Slingsby Gull 4 with a longer fuselage and was at first known as the Gull 5 or the ‘Slingsby 18 metre’, but the name Sky was suggested by John Furlong as it was made up of the initial letters of Slingsby, Kirbymoorside where the firm’s works were, and Yorkshire.

The Gull 4 was intended to be Slingsby’s postwar 15m design, but did not go into production as the rival EoN Olympia was cheaper. The Sky, which resembled it, was of conventional wood and fabric construction; the production aircraft were designated T34A Sky 1 to distinguish them from the improved T34B Sky 2 intended for the 1954 World Championships but not, in the end, built. This version had NACA 64-/63 series wing sections instead of the Mk 1’s Gottingen 547 and NACA 2R 12 aerofoils, and revised squarecut wing tips and tail units. The high single-spar cantilever wings have a leading edge torsion box and a light secondary spar to carry the two-piece ailerons; the wing is fabric covered aft of the main spar and DFS-type air brakes are fitted in the upper surfaces, but there are no flaps. The fuselage is a ply-covered stressed skin wooden structure, and the landing gear is a single fixed monowheel behind an ash skid under the forward fuselage; there is a tail bumper and a jettisonable two-wheel dolly can be used in place of the monowheel. The tailplane is cantilever and the rudder and elevators are fabric-covered. The pilot sits under a one-piece moulded Perspex canopy and has adjustable rudder pedals; oxygen, radio and barographs can be installed for contest flying.

Although only 16 examples were built, the Sky high performance single-seater has a secure place in gliding history as being the first British-designed type to win the World Championships, which it did in 1952 flown by Philip Wills when this event was held at Cuatro Vientos, near Madrid; eight T34 Skys took part, also being flown by the Dutch and Argentine teams, and all but one of them were placed in the first 14, including the 3rd place taken by Robert Forbes. Philip Wills flew his Sky into second place in the 1954 World Championships at Camphill, Bedfordshire, and in the 1956 event this place was taken by Luis Vicente Juez of Spain in another Sky.

T.34 Sky
Span: 18.0 m / 59 ft 0.5 in
Length: 7.65 m / 25 ft 1.25 in
Wing area: 17.37 sq.m / 187 sq.ft
Aspect ratio: 18.7
Wing section: Gottingen 547/NACA 2R 12
Empty weight: 252 kg / 556 lb
Max weight: 363 kg / 800 lb
Water ballast: None
Max wing loading: 20.9 kg/sq.m / 4.28 lb/sq.ft
Max speed: 113 mph / 98 kt / 182 km/h
Stalling speed: 29 kt / 54 km/h
Max rough air speed: 72.5 kt / 134 km/h
Min sinking speed: 0.66 m/sec / 2.17 ft/sec at 39 mph / 33.5 kt / 62 km/h
Best glide ratio: 27.5:1 at 43 mph / 37 kt / 69 km/h

The T. 8 Kirby Tutor (RAF Kirby Cadet T.X. Mk. 2) with a 13.24 m/ 43.4 ft. tapered wing evolved into the T.31 Tandem Tutor (RAF Kirby Cadet T.X. Mk. 3) two-place trainer.

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.

The Tandem Tutor was designed by F. N. Slingsby, first flew in prototype form in September 1950. A two-place development of the single-place T.8 Tutor using the same wings with additional bracing. Early production T.31’s had no aids for approach control, but spoilers were added to later models, and retrofitted to most examples.

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 Royal Air Force used T.31B’s (known as the Kirby Cadet T.X. Mk. 3) in its air cadet organization from 1950 to the mid 1980’s. One ‘Mark 3’ made over 120,000 flights totaling 6,000 hours in this period.

Variations:
Martin & Wilkinson Cadet III

T.31 Tandem Tutor
Wing span: 13.2 m / 43 ft 3.75 in
Wing area: 15.8 sq.m / 170 sq.ft
Airfoil: Gottingen 426
Aspect ratio: 11.1
Length: 7.1 m / 23 ft 3.75 in
Empty Weight: 176 kg / 388 lb
Payload: 442lb/ 200kg
Gross Weight: 830 lb /376 kg
Wing Load: 4.88 lb/sq.ft/ 23.8 kg/sq.m
Water ballast: None
Max speed: 81 mph / 70 kt / 130 km/h
Stalling speed: 33 kt / 61 km/h
L/DMax: 18 @ 73 kph / 39 kt / 45 mph
MinSink: 1.05 m/s / 3.48 fps / 2.06 kt at 42 mph / 36 kt / 67 km/h
No. of Seats: 2
No. Built: 200
Structure: wood/fabric

This single-seat intermediate trainer is basically an updated and improved version of the Grunau Baby, of which Slingsby had built a small number under licence before the war as the T5 Baby.

Of conventional wood and fabric construction, it has a braced wing with air brakes but no flaps, and a nose skid under the forward fuselage just ahead of the non-retractable monowheel; there is also a tailskid, and the tailplane is braced. The pilot sits in an open cockpit and has a small windscreen.

The Prefect, which first flew in prototype form in June 1948, is semi-aerobatic and suitable for cloud flying and cross-country flights.

Altogether 30 Prefects were built for clubs and other civil users, and 16 for the ATC as the T30A Prefect TX Mk 1 (WE979 to WE993 and WG783).

Prefect WG783 was initially delivered with camera mounting fittings and flaps fixed in the down position for the second stage of carrier wake trails, which involved flying a glider from the deck of an aircraft carrier to investigate characteristics of the wake over the flight deck.

Span: 45 ft 0 in
Length: 21 ft 3.5 in
Height: 4 ft 2 in
Wing area: 154 sqft
Aspect ratio: 13.2
Empty weight: 390 lb
Max weight: 587 lb
Max speed: 100 mph
Min sinking speed: 2.75 ft/sec
Best glide ratio: 21:1

A proposed postwar development of the T.13 Petrel was the T.22 Petrel 2, which had a revised cockpit with a step, wing spoilers, a monowheel and a tailplane with elevators, but this version was not built. A Petrel was fitted with a small engine on top of the fuselage in 1947 by Wing-Commander K. H. Wallis but this version of the Petrel was never flown.