Short Seamew

Infobox Aircraft
name = SB.6 Seamew
type = Anti-submarine aircraft
manufacturer = Short Brothers



caption = Seamew prototype XA213
designer =
first flight = 23 August 1953 [Green and Pollinger 1956, p. 260.]
introduced =
retired = 1957
status =
primary user = Royal Navy Fleet Air Arm
more users = Royal Naval Volunteer Reserve
produced =
number built = 19
unit cost =
variants with their own articles =

distinguish2|the 1928 Supermarine Seamew or 1940 Curtiss SO3C Seamew

The Short SB.6 Seamew was a "curious-looking" British aircraft designed in 1951 by David Keith-Lucas of Shorts as a lightweight anti-submarine platform to replace the Royal Navy Fleet Air Arm (FAA)'s Grumman Avenger AS 4 with the Reserve branch of the service. It first flew on 23 August 1953, but, due to poor performance coupled with shifting defence doctrine, it never reached service and only 19 were built before the project was cancelled. It has been described as a "camel amongst race-horses".Winchester 2005, p. 46.]

Design and development

The Short Seamew was selected to fulfill Admiralty Specification M.123D for a simple, lightweight anti-submarine aircraft capable of unassisted operation from any of the Royal Navy's aircraft carriers in all but the worst of conditions. Although specifically designed for naval operations, the Seamew was also intended for land-based use by the RAF. [Flintham, Vic. [http://www.vicflintham.co.uk/post-war-research-aircraft-and-prototypes/Cancelled.html "Short Seamew".] "Cancelled Types", 2007. Retrieved: 12 August 2008.] It was to be suitable for mass production and operation by the Air Branch of the Royal Naval Volunteer Reserve (RNVR). This specification was in response to the alarming increase in capabilities of the Soviet submarine forces following the Second World War.

Three prototypes were ordered in April 1952 and the first flight ("XA209"), piloted by its test pilot, Sqn. Ldr. Walter J. "Wally" Runciman, [Sqdn.Ldr. W.J. Runciman, A.F.C, D.F.M] took place on 23 August 1953. This same aircraft, also piloted by Runciman, took part in the 1953 Farnborough Airshow three weeks later. In 1954 both "XA209" and the second prototype "XA213" took part at Farnborough, where the following year both prototypes and two production AS Mk 1 models ("XE171" and "XE172") gave a formation display. [Barnes and James 1989, pp. 450–453.]

The MR Mark 2 was similar in every respect to the AS Mk 1 except that it was optimised for land-based use from hastily prepared airstrips. Naval equipment was deleted although manual wing folding was retained. Slightly heavier than the naval version, the MR Mk 2 had oversize tyres and could carry a higher weapons load.

Design

The pilot and observer were located in tandem cockpits located high up in the front of the deep, narrow fuselage. They sat atop the Armstrong Siddeley Mamba turboprop in front and the weapons bay to the rear of them. The design had originally called for the tried and tested Rolls-Royce Merlin piston engine but the Royal Navy had made it policy to phase out piston engines, in order that supplies of highly flammable high octane aviation fuel need not be carried in large quantities on ships. The turboprop engine also caused less airframe vibration and would therefore have less impact on the performance of the radar scanner mounted below the engine housing.

For simplicity, and so that a nose wheel would not obscure the forward field of the radar scanner, a fixed tail wheel undercarriage was used. The long stroke necessary on the main undercarriage to give the radar scanner and propeller adequate clearance from the ground resulted in an alarming attitude on the ground and the cockpits mounted at a seemingly perilous height. The pilot and observer sat very far forward in order that the pilot could have a reasonable field of downward vision for takeoff and landing and so that both he and the observer had a good field of view e.g. for spotting submarines even when in level flight.

The large, broad-chord wings featured power-folding and pylons for the carriage of rockets, depth charges, flares and small bombs. The large, slab-like, tailplane was mounted high on the vertical stabiliser, requiring the rudder to be split into upper and lower sections. The fixed undercarriage legs could be jettisoned in the event of ditching.Winchester 2005, p. 47.]

Handling Characteristics

The handling characteristics of the Seamew were poor. The prototypes were heavily modified with fixed leading-edge slats, slots added in the trailing-edge flaps, alterations to the ailerons and slats added to the tailplane roots. Although something of an improvement over the initial models, the handling was never wholly satisfactory. Arthur Pearcy wrote "only Short Brothers' test pilot Wally Runciman seemed able to outwit its vicious tendencies and exploit its latent manoeuvrability to the limit."Pearcy 1990]

Operational service

An order was placed in February 1955 for 60 aircraft (split evenly between the FAA and RAF), with Seamew "XA213" successfully completing carrier trials on HMS "Bulwark" in July and December 1955. Naval service flight trials with two Seamews were carried out with 700 Naval Air Squadron in November 1956, which included catapult trials and around 200 takeoffs and landings on HMS "Warrior".

The RAF lost interest after four Mk 2s were built with three of them converted to AS1 standard; the fourth ("XE175") was flown by S/L W. "Wally" J. Runciman for a series of sales tours in 1956 to Italy (March), Yugoslavia (April) and West Germany (May). It was this same aircraft in which Runciman was killed when he crashed during the Sydenham (Belfast) Air Display on 9 June 1956. Rumours that the crash had been caused by a material failure were current at the time but the accident investigation board did not confirm them.

Meanwhile the FAA decided that the RNVR Avengers would be replaced by Seamews, but only four had been taken on charge by the time the RNVR squadrons were disbanded in March 1957 in keeping with the 1957 Defence White Paper, before any Seamews were allocated to them. Seven aircraft eventually delivered to the FAA were scrapped at RNAS Lossiemouth, and the other 11, complete and awaiting delivery, were scrapped at Sydenham. The last surviving Seamew, "XE180" which had been purchased by Shorts on 31 August 1959 for ground instruction at its Apprentice Training School, was scrapped in 1967. [ [http://www.belfastforum.co.uk/index.php/topic,451.1800.html "XE180"] ]

The Rolls-Royce Heritage Trust has preserved a Seamew engine, which is found at its Coventry branch.

Operators

; UK
* Royal Navy

pecifications (Seamew AS 1)

aircraft specifications

plane or copter?=plane
jet or prop?=prop

ref= [Winchester 2005, pp. 46–47.]

crew=2
payload main=1,844 lb
payload alt=836 kg
payload more=of weapons
length main=41 ft
length alt=12.50 m
span main=55 ft
span alt=16.75 m)
**Wings folded 23 ft (7.01 m
height main= 13 ft 5in
height alt= 4.09 m)
**Wings folded 15 ft 7.5 in (4.76 m
area main=550 ft²
area alt=51 m²
airfoil=
empty weight main=9,795 lb
empty weight alt=4,443 kg
loaded weight main=14,400 lb
loaded weight alt=6,804 kg
max takeoff weight main=15,000 lb
max takeoff weight alt=6,790 kg
more general=

engine (prop)=Armstrong Siddeley Mamba
type of prop=turboprop engine
number of props=1
power main=1,590 shp
power alt=1,190 kW

max speed main=236 mph
max speed alt=205 knots, 380 km/h
range main=750 mi
range alt=650 nm, 1,200 km
ceiling main=
ceiling alt=
climb rate main=
climb rate alt=
loading main=26 lb/ft²
loading alt=127 kg/m²
power/mass main=0.11 hp/lb
power/mass alt=180 W/kg
more performance=

bombs=
** 1× torpedo
** 4× depth charges
rockets=Several rockets carried underwing
Sonobuoys: 20

avionics=

ee also

aircontent

related=

similar aircraft=
* Fairey Gannet
* Grumman Avenger

sequence=
* Solent - S.25 (Sunderland) - SB.1 - SA/4 (Sperrin) - SB/6 (Seamew) - SB/4 (Sherpa) - SC.1 - SC.7 (Skyvan) -

lists=
* List of aircraft of the Fleet Air Arm

see also=

References

Notes

Bibliography

* Barnes, C.H. with revisions by Derek N. James. "Shorts Aircraft since 1900". London: Putnam, 1989 (revised). ISBN 0-85177-819-4.
* Green, William and Gerald Pollinger. "The Observer's Book of Aircraft". London: Frederick Warne & Co. Ltd. 1956.
* Pearcy, Arthur. "Short Seamew". "Aviation News 6", 19 July 1990.
* Runciman, Squadron Leader W.J. "Pilot's Flying Log Book". "Squadron Leader W.J. Runciman, A.F.C., D.F.M." Original held by his family, a copy held by P. Sortehaug, 4, William St., Dunedin, NZ.
* "The Seamew Calls a Halt to the Rising Cost of Air Power." "Shorts Quarterly Review, Vol. 2, No. 3, Autumn 1953".
* "The Short Seamew Light Anti-submarine Aircraft" (promotional brochure). Belfast: Short Brothers and Harland Limited, c. 1953.
* Williams, Ray. "Fly Navy: Aircraft of the Fleet Air Arm since 1945". London: Airlife Publishing, 1989. ISBN 1-85310-057-9.
* Winchester, Jim, ed. "Short Seamew". "The World's Worst Aircraft: From Pioneering Failures to Multimillion Dollar Disasters". London: Amber Books Ltd., 2005. ISBN 1-904687-34-2.

External links

* [http://www.aviationarchive.org.uk/Gpages/html/G3631.html Short Seamew AS1]
* [http://www.vicflintham.co.uk/post-war-research-aircraft-and-prototypes/Cancelled.htmlCancelled Types]