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SHERPA JET SB.4

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Image: ALAN JARDEN

History of the Shorts Sherpa SB.4 prototype

In 1947, Shorts submitted a bomber design to meet the V-bomber requirement B.35/46 for the best possible performance at the highest altitude. The design (PD.1) was essentially the Short Sperrin fuselage with a new tail and what was described as an 'aeroisoclinic wing'.

 

Handley Page and Avro's designs for the requirement were both accepted and contracts were received to build small-scale powered prototypes to explore the handling characteristics.

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Image: SHORTS ARCHIVE

Shorts decided to keep up to speed with their own concept at their own expense and set about construction of a one third scale glider of the PD.1 called the SB.1.

 

The aircraft was also the first to be wholly designed and built in Belfast after Shorts transfer from Rochester and construction was to be as inexpensive as possible.

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Image: SHORTS ARCHIVE

The concept of the 'aero-isoclinic' was a swept-wing in which the angle of incidence  would remain constant from root to tip. It's most striking feature however was that the wing tips comprising of about one-fifth of the total wing area, could pivot and acted as the control surfaces.

 

In July 1951 the SB.1 was taken to Aldergrove Airport for its initial flights, to be towed by a Shorts Sturgeon aircraft. On the second flight the whole program suffered a setback when the glider piloted by Tom Brooke-Smith, was forced to cast-off the tow line before gaining  much height and crashed on the runway.

The SB.1 glider being towed behind a Shorts Sturgeon before it crashed on the runway at Aldergrove

Image: SHORTS ARCHIVE

Tom Brooke-Smith was injured and resumed flying six months later. For the SB.1 however, with the fuselage a total wreck its chances for becoming airborne again probably seemed slim.

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Image: SHORTS ARCHIVE

With the damage to the SB.1 assessed and the wing and tail found to be repairable a decision was made to continue the project. Tom Brooke Smith however objected to making any further flights in the machine as a glider, so a new fuselage was designed incorporating two Turbomeca Palas turbojets mounted to the rear of the wing, and a fixed tricycle undercarriage was also added.

 

The rebuilt monoplane, now designated SB.4, was flown at Aldergrove on 4th October 1953.

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Image: SHORTS ARCHIVE

Although limited to 250mph and 5000ft altitude the aircraft demonstrated good handling qualities and the following year was was demonstrated at the S.B.A.C show at Farnborough under the new name Sherpa, an acronym of 'Short & Harland Experimental Research Prototype Aircraft', and also maybe a reference to the then recent conquest of Everest.

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Image: SHORTS ARCHIVE

Throughout its test program, results were analysed and information acquired, but the concept probably proved to be slightly disappointing in practice, and manufacturers were learning how to build conventional wings that behaved satisfactorily at high sub-sonic mach numbers.

 

There were several further aero-isoclinical proposals from Shorts, one for the Supermarine Swift with an aero-isoclinical wing, and a design for the NA.39 Naval Strike Bomber, a requirement that was eventually won by the Blackburn Buccaneer.

On completion of the Flight test program in 1956 the Sherpa was given to the college of aeronautics at Cranfield for research and remained airworthy until 1964 when the engines became time expired. It was then transferred to the Bristol College of Advanced Technology as an instructional aircraft, and in May 1966 was presented to the Skyfame Aircraft Museum at Staverton.

History of the Shorts Sherpa SB.4 restoration

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Image: ALAN JARDEN

When Skyfame closed in 1979 the fuselage found its way to the Imperial War Museum at Duxford. The three parts of the wing had by then unfortunately gone missing, and the fuselage remained in storage there for many years until it was decided to try to restore it, with the work being undertaken by the Medway Aircraft Preservation Society (MAPS) based in Rochester.

 

In 2001, MAPS put out a request to any organisations that might be able to supply them with a pair or Turbomeca Palas turbojet engines and by chance the original pair of Palas engines from the Sherpa had been stored at Shorts Belfast for many years before being donated to the Ulster Aviation Society.

Hangar volunteers, Peter Morrison (foreground) and WIlliam Smyth patiently working to make the experimental Sherpa SB.4’s jet's wingtips pivot.. Image: Mark J. Cairns

Image: MARK J. CAiRNS

Several phone calls and a few months later an RAF Puma from 230 Squadron Aldergrove arrived at the UAS original home in Langford Lodge to collect the engines and take them to Rochester for installation in the restored Sherpa.

 

With the fuselage's restoration work complete the aircraft was then offered on long term loan to the Ulster Aviation Society by the IWM, and joined the Heritage Collection, at Maze Long Kesh in 2008 where its ground-breaking aero-isoclinic wings are currently being recreated by UAS volunteers, Peter Morrison and William Smyth.

Shorts Sherpa SB.4 XXXL R/C flying model

Manufacturer: Shorts
Model: Sherpa Jet SB.4
Prototype (Experimental)
First Flight: 4th Oct, 1953
Registration: G014-1
UAS Location: Hangar 1
UNDER RESTORATION
Maximum Speed:  250 mph at 5,000ft
Engines: 2 × Blackburn Turbomeca Palas turbojets, 350 lbf (1.6 kN) thrust each
Service Ceiling: 5,000 ft
Length & Height9.7m x 2.77m
Wing Span: 11.58m with sweepback of 42 degrees​​