Short SB.4 Sherpa
SB.4 Sherpa | |
---|---|
Short Sherpa demonstrating at the Farnborough SBAC Show in September 1954 | |
Role | Experimental aircraft |
National origin | United Kingdom |
Manufacturer | Short Brothers |
Designer | David Keith-Lucas |
First flight | 4 October 1953 |
Number built | 1 |
Developed from | Short SB.1 |
The Short SB.4 Sherpa was an experimental aircraft designed and produced by the British aircraft manufacturer Short Brothers. Only a single example was ever produced.
The Sherpa was developed during the 1950s for the purpose of testing a novel wing design, referred to as an aero-isoclinic wing. It was believed that this wing design could possess favourable qualities for producing tailless aircraft, and that the Sherpa would validate the characteristics of the wing for such aircraft to be produced in the future. While such a wing had been flown on the earlier Short SB.1, an unpowered glider, it was deemed valuable to use a powered aircraft instead. The design of the Sherpa is largely based upon that of the SB.1, to the extent that it incorporated numerous elements of this aircraft.
The Sherpa performed its maiden flight on 4 October 1953, after which it spent several years performing experimental flights and the occasional aerial display. After gathering sufficient data for Shorts' purposes, the company decided that it did not show sufficient potential as to continue its research into the aero-isoclinic wing. The sole Sherpa was donated to the College of Aeronautics at Cranfield during the late 1950s and flown for numerous years. It was eventually grounded and used as a static laboratory specimen at the Bristol College of Advanced Technology, before being preserved and put on display at the Norfolk and Suffolk Aviation Museum.
Development
The origins of the Short SB.4 Sherpa can be traced back to the 1920s and the activities of Professor
In particular, one of the company's aeronautical engineers, David Keith-Lucas, was keen to eliminate the parasitic drag normally incurred by the presence of a conventional tail and fuselage, and thus was a keen proponent of the tailless approach.[3] He also observed that directional stability was a critical issue without the application of traditional fins and rudders; it was identified that the outermost parts of the wing could be rotated and repositioned to function as elevons for stability and control purposes. New wing designs that presented a low aspect ratio, such as the delta wing, had been observed to reduce the onset of these issues; Keith-Lucas and Hill, jointly developed what became known as the aero-isoclinic wing.[4]
Having become sufficiently confident in the merits of the aero-isoclinic wing , Shorts opted to produce a new experimental aircraft to incorporate the latest advances and explore its behaviour, thus it constructed the
Design
The Short SB.4 Sherpa was an experimental aircraft, featuring an unusual
In the Sherpa, the wing, which was used without a
In terms of its construction, the Sherpa was primarily composed of light alloys and featured a monocoque arrangement.[8] Wing sweep-back on the leading edge was just over 42° to facilitate low-speed research. The Sherpa was provisioned with a conventional tricycle undercarriage.[8] Two diminutive engines (Turbomeca Palas) were buried in the upper fuselage with a NACA flush inlet on the top of the fuselage and toed-out exhausts located at the wing roots. Fuel was housed within the fuselage in two 250 gallon tanks, which were balanced around the aircraft's centre of gravity; electrical power was supplied by a ram air turbine by the engines.[9] Blackburn, who produced the Palas under licence, hoping to market these engines as a new product line, supplied the powerplants for the Sherpa programme.[10]
Testing
On 4 October 1953, the Sherpa performed its maiden flight, piloted by Shorts' Chief Test Pilot, Tom Brooke-Smith.[9] Brooke-Smith had also piloted the earlier experimental glider aircraft, the Short SB.1, upon which the Sherpa was based. Although he sustained injuries in the crash landing of the SB.1, Brooke-Smith had quickly recovered and was able to undertake the test programme of the redesignated SB.4 (registered as G-14-1) throughout 1953–1954. (Incidentally, the Sherpa was named following the conquest of Mount Everest but derived its name specifically from its company designation "Short & Harland Experimental Research Prototype Aircraft.[9])
During the initial series of flying trials of the Sherpa, performed largely by Brooke-Smith, the aircraft had reportedly proved to be quite satisfactory; its docile handling characteristics led to be being described as being 'one of the most graceful aircraft now flying'.[11][9] The aircraft was typically flown within a restricted flight envelope, during which it reportedly achieved a "flat-out" speed of 170 mph (270 km/h) at 5,000 ft (1,500 m),[12] which made it amongst the slowest jet-powered aircraft to have ever flown.[12][13]
Data from these flights was typically captured by an onboard
The Sherpa itself was subsequently donated to the
Aircraft on display
The sole SB.4 is on display at the Ulster Aviation Collection, Long Kesh Airfield, near Belfast[19]
Specifications
Data from Shorts Aircraft since 1900.[20]
General characteristics
- Crew: 1
- Length: 31 ft 10 in (9.7 m)
- Wingspan: 38 ft 0 in (11.58 m) sweepback 42 degrees
- Height: 9 ft 1.12 in (2.77 m)
- Wing area: 230 sq ft (21.4 m2)
- Empty weight: 3,000 lb (1,400 kg)
- Gross weight: 3,268 lb (1,482 kg)
- Powerplant: 2 × Blackburn Turbomeca Palas turbojet, 350 lbf (1.6 kN) thrust each
Performance
- Maximum speed: 170 mph (275 km/h, 150 kn)
- Cruise speed: 117 mph (188 km/h, 102 kn)
- Endurance: 45-50 min
- Service ceiling: 5,000 ft (1,500 m)
See also
Related development
References
Citations
- ^ Barnes 1967, pp. 439-440.
- ^ Barnes 1967, pp. 439-441.
- ^ Barnes 1967, p. 441.
- ^ a b Barnes 1967, pp. 441-442.
- ^ Barnes 1967, p. 442.
- ^ a b Barnes 1967, pp. 442-443.
- ^ Barnes 1967, pp. 441-443.
- ^ a b c Barnes 1967, pp. 443-444.
- ^ a b c d e Barnes 1967, p. 444.
- ^ Gunston 1977, p. 512.
- ^ Shorts Quarterly Review, Autumn 1953.
- ^ a b Barnes and James 1989, p. 444.
- ^ a b c Gunston 1977, p. 513.
- ^ Barnes 1967, pp. 444-445.
- ^ a b Barnes 1967, p. 445.
- ^ Barnes and James 1989, p. 445.
- ^ Barnes 1967, pp. 445-446.
- ^ Ulster Aviation Society SB4 page
- ^ Ulster Aviation Society website
- ^ Barnes and James 1989, p. 446.
Bibliography
- Barnes, C.H. Shorts Aircraft since 1900. London: Putnam, 1967.
- Barnes, C.H. with revisions by Derek N. James. Shorts Aircraft since 1900. London: Putnam, 1989 (revised). ISBN 0-85177-819-4.
- Buttler, Tony (May–June 1999). "Control at the Tips: Aero-isoclinics and Their Influence on Design". Air Enthusiast (81): 50–55. ISSN 0143-5450.
- Buttler, Tony and Jean-Louis Delezenne. X-Planes of Europe: Secret Research Aircraft from the Golden Age 1946-1974. Manchester, UK: Hikoki Publications, 2012. ISBN 978-1-902-10921-3
- Gunston, Bill. "Short's Experimental Sherpa." Aeroplane Monthly, Vol. 5, no. 10. October 1977, pp. 508–515.
- "Sherpa - Fore-runner of High Speed, High Altitude Aircraft." Shorts Quarterly Review, Vol. 2, No. 3, Autumn 1953.
- Warner, Guy (July–August 2002). "From Bombay to Bombardier: Aircraft Production at Sydenham, Part One". ISSN 0143-5450.