Short Sturgeon

Le Short Sturgeon sur Wikipedia version de langue anglaise

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The Short Sturgeon was a British aircraft originally designed in the Second World War as a high-performance torpedo bomber.

With the end of the war in the Pacific it was no longer needed as such.

Through shifting priorities postwar, the Sturgeon was redesigned first into a target tug and then later as a prototype anti-submarine aircraft.

The many modifications that resulted turned the promising design into a hapless and grotesque-looking hybrid.

Design and development

The (S.A.1) Sturgeon began life as a high-performance torpedo bomber during the Second World War with a bomb bay that could accommodate six 500 lb bombs or any of the current standard airborne torpedoes, operating from Audacious and Centaur-class aircraft carriers.

The torpedo requirement was dropped when the Second World War ended and plans for large aircraft carriers were abandoned.

Specification S.11/43 for a naval reconnaissance aircraft called for the design and construction of a twin-engine reconnaissance aircraft for visual and photographic reconnaissance and shadowing, by day or night.

The specification included a maximum all-up weight of 24,000 lb, height (stowed) of 17 ft, length of 45 ft and a wingspan of 60 ft (spread)/20 ft (folded). Power wing-folding was also required.

The contract went to Short Brothers for their revised S.38 Sturgeon as the PR.Mk 1 on 12 February 1944 for three prototypes, with military serials RK787, RK791 and RK794 assigned.
The first Short S.A.1 Sturgeon I RK787 flew at Rochester Airport on 7 June 1946, appearing at Farnborough in July Deck landing trials were completed in 1947.

The second, RK791, flew from Sydenham, Belfast on 18 May 1948.

The pilot's cockpit was a sub assebly bolted to the front of the spar, the navigator was behind the centre section of the wing and the radio operator - separated from the navigator by his equipment - behind him.

The navigator and radio operator entered through a door, which acted as a ladder when opened, in the starboard side: their seats being offset to port.

The cameras were installed in the fuselage behind the radio operator Armament would be two 0.5 inch machine guns with a 1000 lb bomb or two 500 lb bombs (or depth charges).

The PR.1 competed in the Air League Challenge Cup Race of 1949 with an average speed of 295 mph.

The production series of 100 aircraft was cancelled but the design stayed alive with modifications to accommodate a target-tug role as the S.39 (also known as S.A.2) Sturgeon. A third prototype, RK794, was modified to a Mk 2 standard with a new serial, VR363.

The TT Mk 2 featuring an all-metal construction, mid-wing cantilever monoplane, was a large but clean-looking twin-engined design with a distinctive glazed nose in its target tug configuration.

The all-metal monocoque was built in four sections ending at a cantilever tailplane with single fin and rudder.
Rudder and tailplanes were fabric covered.

The wing design featured a swept leading edge and taper on outboard sections and wing folds outboard of the twin Rolls-Royce Merlin 140 engines driving contra-rotating propellers which allowed shorter blades and the Merlins being mounted closer to the centreline.

The main wheels retracted rearwards into the engine nacelles while the tail wheel retracted forwards into the fuselage. Radiators were mounted in the leading edge between the nacelles and the fuselage.

The Sturgeon's postwar role began as a naval liaison and target tug aircraft with modifications to the nose, lengthened to provide a crew position forward of the propeller arcs and a winch system.

The crew of two included a pilot in an enclosed cockpit, level with leading edge of wing.

The all-purpose "observer" in the nose had to perform the functions of "navigator, wireless operator, target operator and camera operator. He moved between stations in the nose and rear fuselage.".

Five TT2s were further converted into the less-sophisticated TT3 variant.

The penultimate and last Sturgeons were redone as prototypes for a proposed anti-submarine aircraft, powered by two Armstrong Siddeley Mamba AS Ma3 turboprops of 1,147 hp (1,100 kW) driving two four-bladed propellers.

The engine exhausts were directed down instead of to the rear.

Another major modification was the grafting on of a gigantic bulbous nose that housed two radar operators in stations forward of the engines and the radar itself below.

Acute problems arising from the resultant "schnoz" led to the demise of the project — "the efflux from the Mamba turboprops seriously destabilized the aircraft at some power settings and destroyed the good handling characteristics.

It proved impossible to trim for safe flight on one engine which was a necessity for long endurance on anti-submarine patrols."

Two Sturgeon SB 3 prototypes were ordered with the first, WF632 flying on 8 December 1950 at Belfast.

The design proved extremely difficult to trim when flying on one engine and so unstable that no effort was made to resolve these problems, consequently, the project was cancelled before the second prototype, WF636 flew.

Both aircraft had very short lives, being scrapped in 1951.

Operational service

The main production variant, the TT2 naval target tug (TS 475 – TS 498) spent most of its life with No. 728 Squadron at Hal Far, Malta.

They also operated with No. 771 Squadron at RNAS Ford in 1950- 1954.

Their primary role as a target tug included towing targets for ground-to-air firing practice, photographic marking of ground-to-air firing, target towing for air-to-air practice by night and day, "throw-off," target practice and radar calibration.

All existing Sturgeon TT2s were modified to a (S.B.9) TT3 standard during the early 1950s. The TT3 variant was intended to meet less stringent requirements.

The extended TT2 nose with its synchronised photographic equipment and crew station was removed and replaced by a smaller streamlined nose cone.

With the change from carrier operations to ground bases, all deck-landing equipment was also eliminated as well as the wing being modified to have a manual folding gear in place of the TT2's hydraulic system.

Briefly, a Short Sturgeon TT2 (VR363) piloted by "Jock" Eassie was utilised as a glider tow aircraft in the Short SB.1 flight tests.

The experimental "tailless" glider, designed by David Keith-Lucas and Professor Geoffrey T.R. Hill, was built by Shorts as a private research venture and intended to test the concept of the aero-isoclinic wing.

The first towed launch of the SB.1 piloted by Shorts' Chief Test Pilot, Tom Brooke-Smith ("Brookie") took off from RAF Aldergrove on 30 July 1951.

The SB.1 was towed behind to a height of 10,000 ft with the flight completed successfully.

On the second flight of the day, the tow rope was extended and Brooke-Smith experienced the problems inherent in flying a light aircraft in the turbulence caused by the towing aircraft.

Brooke-Smith had to cast off at low altitude and while attempting to side-slip out of the wake, struck the ground "nose-down" at 90 mph, injuring himself seriously and damaging the aircraft.

With the extensive damage to the Short SB.1 necessitating a rebuild, the decision to "power" the modified glider (redesignated the Short Sherpa) meant the end of the use of the Sturgeon tow plane in the program.

Variants

* S Mk 1 gunnery trainers built at Shorts, Rochester

* TT Mk 2 target tugs (further converted to the TT Mk 3 standard)

* SB.3 prototype anti-submarine aircraft built in Belfast. One SB.3 was demonstrated at the 1951 Society of British Aerospace Companies' (SBAC) Farnborough Airshow; the second example was completed but never flown.

Un des prototypes du SB-3

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Operators

United Kingdom

* Royal Navy, Fleet Air Arm

o 728 Naval Air Squadron
o 771 Naval Air Squadron