Short SB.4 Sherpa

The origins of the Short SB.4 Sherpa can be traced back to the 1920s and the activities of Professor Geoffrey T.R. Hill, who was pivotal in the design of the Westland-Hill Pterodactyl, a pioneering tailless experimental aircraft. Even prior to the First World War, Shorts had been involved in tailless aircraft research, but interest in the field reached new heights in the years immediately following the Second World War. During the late 1940s, the company worked on multiple proposals for tailless aircraft in response to specifications issued by the Air Ministry, including Specification X.30/46 and Specification B.35/46, which sought a military assault glider and strategic bomber respectively. 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. 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. This aircraft was designed to be as inexpensive as possible and thus featured extensive wooden construction alongside its innovative wing. After only a few months of flight, the SB.1 suffered damage in a heavy landing at RAF Aldergrove on 17 October 1951. Shorts' chief test pilot, Tom Brooke Smith, objected to further flights of the unpowered glider. Accordingly, it was decided that the fuselage, which had been heavily damaged, would be replaced by a modified design that incorporated a pair of Turbomeca Palas turbojet engines. ==Design==

The Short SB.4 Sherpa was an experimental aircraft, featuring an unusual aero-isoclinic wing. In the Sherpa, the wing, which was used without a tailplane, was fitted with rotating tips comprising approximately one-fifth of the total wing area. Unlike pure wingtip ailerons, these surfaces were a bit more like "wingtip elevons", as they were rotated together (to act as elevators) or in opposition (when they acted as ailerons). They were hinged at about 30% chord and each carried, on the trailing edge, a small anti-balance tab, the fulcrum of which could be moved by means of an electric actuator. It was expected that the rotary wing tip controls would prove greatly superior to the flap type at transonic speeds and provide greater manoeuvrability at high altitudes. In terms of its construction, the Sherpa was primarily composed of light alloys and featured a monocoque arrangement. Blackburn, who produced the Palas under licence, hoping to market these engines as a new product line, supplied the powerplants for the Sherpa programme. ==Testing==

On 4 October 1953, the Sherpa performed its maiden flight, piloted by Shorts' Chief Test Pilot, Tom Brooke-Smith. which made it amongst the slowest jet-powered aircraft to have ever flown. Data from these flights was typically captured by an onboard flight data recorder and analysed post-flight to build up a model of how a similar full-sized wing would behave under various conditions, including various altitudes and speeds. Aviation author Bill Gunston notes that, despite the Sherpa having attaining its design goals, the concept was considered to be "not fully realised in practice" and the project was eventually wound up without a direct continuation. The Sherpa itself was subsequently donated to the College of Aeronautics at Cranfield, where it continued to fly up until 1958. At this point, engine issues forced the aircraft to be grounded until replacement powerplants could be organised. Its fuselage was on display at the Norfolk and Suffolk Aviation Museum, near Bungay, Suffolk, until 17 July 2008, after which it was moved to the Lisburn site of the Ulster Aviation Society. == Aircraft on display ==

The sole SB.4 is on display at the Ulster Aviation Society, Long Kesh Airfield, near Belfast ==Specifications==