Short SB.1

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SB.1

Short SB.1 during landing c.1951
Type	Experimental glider
Manufacturer	Short Brothers
Designed by	David Keith-Lucas
Maiden flight	14 July 1951
Status	Company experimental project
Number built	1
Variants	Short SB.4 Sherpa

The British Short SB.1 was a tailless glider designed by David Keith-Lucas and Professor Geoffrey T.R. Hill and built by Shorts as a private research venture to test the concept of the aero-isoclinic wing, it being the first aircraft to incorporate this feature. It was in effect a one-third scale glider version of Keith-Lucas' ambitious preliminary design P.D.1,^[1]^[2] intended to meet the Air Ministry's (V bomber) specification B.35/46, which was the basis for the Avro Vulcan, the Handley-Page Victor and the Vickers Valiant.

1 Design and development
2 Testing
3 Specifications
4 References
5 Related content

[edit] Design and development

After extensive testing with wind-tunnel and flutter models, the design team proposed that a manned glider be built.^[3] Shorts (Belfast) undertook construction on a single-seat glider incorporating the "aero-isoclinic" wing originated by Professor Hill.

The SB.1 glider was designed to be an inexpensive, simple machine, constructed primarily of spruce with reinforced sections using light alloy steel. The all-important wing controls had "elevons" pivoted on long, tapered light-alloy tubes extending from the leading edge of the tip, just inside the fixed part of the wing (illustrated by photographs in the Short Sherpa article). The pivoting mechanism had a double-ball bearing unit on the inboard end with main loads transferred to a needle roller bearing at the outboard end of the fixed wing. Anti-balance tabs were fitted along trailing edges along with small pneumatically actuated flaps under the inboard sections. When the elevons were rotated in the same direction they functioned as elevators; when rotated in opposite directions they functioned as ailerons.

[edit] Testing

After final construction at Aldersgrove, the Shorts SB.1 bearing Class B registration G-14-5 was readied for flight testing early July 1951. For the first flight on 14 July 1951, the SB1 was winch-launched and the gliding characteristics were found by Shorts' Chief Test Pilot Tom Brooke-Smith ("Brookie") to be satisfactory.

A further successful test flight on 15 July 1951 was followed by the first towed launch from RAF Aldergrove on 30 July 1951. The SB.1 was towed behind a Short Sturgeon TT2 (VR363) piloted by "Jock" Eassie to a height of 10,000 ft, the height of the release. Although Brooke-Smith experienced turbulence inherent in flying a light aircraft in the wake of the towing aircraft, the subsequent test flight was completed successfully. During the second flight of the day (using a longer towline intended to alleviate the turbulence), the test pilot encountered severe buffeting problems and he had to cast off at low altitude. The flight ended catastrophically when Brooke-Smith attempted to side-slip out of the wake and struck the ground "nose-down" at 90 mph, injuring himself seriously and heavily damaging the aircraft.

During his recovery, Brooke-Smith expressed concerns about the towed launches and was adamant that testing the SB.1 required a new approach. The Shorts company persevered with the project, redesigning the aircraft six months later. The new design retained the wings and tail of the SB.1 but (at Tom Brooke-Smith's insistence) featured two small turbojet engines housed in a new, light-alloy fuselage. The result was the Short SB.4 Sherpa.

[edit] Specifications

General characteristics

Crew: 1
Length: ft in (m)
Wingspan: ft in (m)
Height: ft in (m)
Wing area: ft² (m²)
Empty weight: lb (kg)

Performance

[edit] References

^ The first in a series of Preliminary Designs initiated by Keith-Lucas in 1947
^ Barnes and James, p.442.
^ Gunston 1977, p.512.

Barnes, C.H. with revisions by James, Derek N. Shorts Aircraft since 1900. London: Putnam, 1989 (revised). ISBN 0-85177-819-4.
Gunston, Bill. "Short's Experimental Sherpa." Aeroplane Monthly Vol. 5, no. 10, October 1977. p. 508-515.
Short SB4 Sherpa RAF (EJA18c philatelic cover). Croydon, Surrey, UK: Aviation Collectables. [1] Access date: 1 February 2007.