The Short R.24/31 (or Short S.18 and nicknamed the ''Knuckleduster'') was a British twin-engined, high-wing cantilever

gull wing The gull wing is an aircraft wing configuration, known also as ''Pulaski wings'', with a prominent bend in the wing inner section towards the wing root. Its name is derived from the seabirds which it resembles. Numerous aircraft have incorpora ...

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

flying-boat A flying boat is a type of fixed-winged seaplane with a hull, allowing it to land on water. It differs from a floatplane in that a flying boat's fuselage is purpose-designed for floatation and contains a hull, while floatplanes rely on fusela ...

designed and built by

Short Short may refer to: Places * Short (crater), a lunar impact crater on the near side of the Moon * Short, Mississippi, an unincorporated community * Short, Oklahoma, a census-designated place People * Short (surname) * List of people known as ...

Air Ministry specification This is a partial list of the British Air Ministry (AM) specifications for aircraft. A specification stemmed from an Operational Requirement, abbreviated "OR", describing what the aircraft would be used for. This in turn led to the specification ...

R.24/31 for a "General Purpose Open Sea Patrol Flying Boat". The contract also specified the use of the experimental

Rolls-Royce Goshawk The Rolls-Royce Goshawk was a development of the Rolls-Royce Kestrel that used evaporative or steam cooling. In line with Rolls-Royce convention of naming piston engines after birds of prey, it was named after the goshawk. The engine first ...

engine. The Saunders-Roe London and the

Supermarine Stranraer The Supermarine Stranraer is a flying boat designed and built by the British Supermarine Aviation Works company at Woolston, Southampton. It was developed during the 1930s on behalf of its principal operator, the Royal Air Force (RAF). It wa ...

competed successfully for this contract. Although it never saw military service, the Knuckleduster provided useful information on the steam-cooling of engines and the handling of monoplane flying-boats; much experimental data gathered contributed to the design of the successful

Empire An empire is a "political unit" made up of several territories and peoples, "usually created by conquest, and divided between a dominant center and subordinate peripheries". The center of the empire (sometimes referred to as the metropole) ex ...

and

Short Sunderland The Short S.25 Sunderland is a British flying boat patrol bomber, developed and constructed by Short Brothers for the Royal Air Force (RAF). The aircraft took its service name from the town (latterly, city) and port of Sunderland in North Ea ...

aircraft.Barnes and James 1989, p. 284.

Design and development

The British Air Ministry issued its Specification R.24/31 for a "General Purpose Open Sea Patrol Flying Boat" in 1931 and ordered one prototype from each of

Saunders-Roe Saunders-Roe Limited, also known as Saro, was a British aero- and marine-engineering company based at Columbine Works, East Cowes, Isle of Wight. History The name was adopted in 1929 after Alliott Verdon Roe (see Avro) and John Lord took a c ...

Supermarine Supermarine was a British aircraft manufacturer that is most famous for producing the Spitfire fighter plane during World War II as well as a range of seaplanes and flying boats, and a series of jet-powered fighter aircraft after World War II ...

and Shorts. Whereas the other two companies opted for traditional biplane designs, Shorts decided to produce a more modern, all-metal monoplane aircraft with the experimental steam-cooled, cast block Rolls-Royce Goshawk engine, itself a development of the smaller

Kestrel The term kestrel (from french: crécerelle, derivative from , i.e. ratchet) is the common name given to several species of predatory birds from the falcon genus ''Falco''. Kestrels are most easily distinguished by their typical hunting behaviou ...

engine. The Knuckleduster's straight-sided hull was of all-metal (

Alclad Alclad is a corrosion-resistant aluminium sheet formed from high-purity aluminium surface layers metallurgically bonded (rolled onto) to high-strength aluminium alloy core material. It has a melting point of about 500 degrees celsius, or 932 degree ...

) box-section construction, from the bow as far as the pointed main step at the rear of the planing bottom; aft of the main step the fuselage was of monocoque construction. The central section of the hull was boxed and braced by diagonal frames to bear the loads from the wing-root attachments. The wing sections inboard of the engines were attached at a 30°

dihedral angle A dihedral angle is the angle between two intersecting planes or half-planes. In chemistry, it is the clockwise angle between half-planes through two sets of three atoms, having two atoms in common. In solid geometry, it is defined as the un ...

, thus providing sufficient clearance for the airscrews from water-spray during

takeoff Takeoff is the phase of flight in which an aerospace vehicle leaves the ground and becomes airborne. For aircraft traveling vertically, this is known as liftoff. For aircraft that take off horizontally, this usually involves starting with a ...

. The wings were designed for high torsional stiffness, each comprising a box-spar with four tapered stainless steel tubular booms. Fuel tanks were mounted within the wings; sprung and braced wingtip floats were fitted. The wing surfaces were of fabric. The experimental 720 hp Rolls-Royce Goshawk steam-cooled engine was specified for the "Knuckleduster," which led to many problems due to the engine's unreliability. The engines, with conspicuous condensers protruding vertically from the nacelles, were mounted at the "knuckle" between the dihedral inner and the horizontal outer wing sections. The tail unit comprised a horizontal plane braced by struts with two vertical fins and rudders, also supported by diagonal bracing to the fuselage. As a result of early test results, fin area was increased; a major redesign of the tail unit was requested by John Parker and implemented at considerable cost. In addition to the enclosed cockpit in which the pilot and the navigator sat side by side, there was a gunner's cockpit in the bow, stations for the engineer and radio operator and a navigator station with a chart-table, sighting ports and two folding bunks. A third folding bunk and two fixed bunks were mounted in the crew's living quarters, which also included a galley and, further aft, stowage space for

drogue A drogue (also known as a storm drogue) is a device trailed behind a boat on a long line attached to the stern. A drogue is used to slow the boat down in a storm and to prevent the hull from becoming side-on to the waves. A boat that has deploye ...

s and a lavatory. Further armament was provided by a midships gun mounting and a rear gunner's cockpit in the tail; bombs could be mounted in underwing bomb racks and there was also provision for a

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, s ...

to be transported (but not launched). All guns mountings carried a single Lewis Gun.

Operational history

First launched the previous day, the first flight of the prosaically named R.24/31 ( serial ''K3574'') took place on 30 November 1933, piloted by Shorts' Chief Test Pilot

John Lankester Parker John Lankester Parker OBE FRAeS Hon. MSLAE (1896 – 22 August 1965) was Chief Test Pilot for Short Brothers from 1918 until his retirement in 1945. He joined Shorts in 1916 as a part-time test pilot and assistant to then Chief Test Pilot Ronald ...

and crewed by George Cotton and W. Howard Bell.Barnes and James 1989, p. 282. Parker noted that the fins were flexing so he landed immediately. After the fins had stiffening added, the aircraft flew again successfully on 15 December. Other problems found during testing were that the boat could not be trimmed straight and level: the fin area was increased by 18% and the tail was re-designed, including fitting a cupola over the tail gun position. On 12 June 1934, at the conclusion of test flying, the Knuckleduster was flown to Felixstowe for official trials with the

Marine Aircraft Experimental Establishment The Marine Aircraft Experimental Establishment (MAEE) was a British military research and test organisation. It was originally formed as the Marine Aircraft Experimental Station in October 1918 at RAF Isle of Grain, a former Royal Naval Air Serv ...

(MAEE).Barnes and James 1989, p. 283. The aircraft was judged not to meet the specification, particularly regarding top speed and range, even though these were not a priority in the specification. In October 1934 the boat was returned to Rochester for repair following an accident - a collision with another flying-boat. It was repaired and several modification incorporated before it returned to Felixstowe in March 1935. In April the Knuckleduster joined 209 Squadron at

RAF Mount Batten RAF Mount Batten was a Royal Air Force station and flying boat base at Mount Batten, a peninsula in Plymouth Sound, Devon, England. Originally a seaplane station opened in 1917 as a Royal Navy Air Service Station Cattewater it became RAF Catte ...

, Plymouth for service trials alongside the Stranraer and

London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...

.Air Pictorial May 1971, p.176. This included an appearance at the Royal Air Force display at Hendon. It was returned to the MAEE in October 1935. Despite suffering engine problems, it continued to carry out trial flights until September 1938, when it was retired from flying duties and assigned to No. 2 School of Technical Training at

RAF Cosford Royal Air Force Cosford or RAF Cosford (formerly DCAE Cosford) is a Royal Air Force station in Cosford, Shropshire, just to the northwest of Wolverhampton and next to Albrighton. History Origins RAF Cosford opened in 1938 as a joint aircraf ...

for instructional purposes. Although it was not ordered into production - mainly hindered by the unreliable engines - a new Air Ministry Specification R.2/33 was released before it flew, which would lead to the

. The Sunderland was another large monoplane flying-boat that had benefited from the work on the R.24/31.

Operators

; *

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...

No. 209 Squadron RAF Number 209 Squadron of the British Royal Air Force was originally formed from a nucleus of "Naval Eight" on 1 February 1917 at Saint-Pol-sur-Mer, France, as No. 9 Squadron Royal Naval Air Service (RNAS)Rawlings 1978, p. 324. and saw active servic ...

Specifications

References

Notes

Bibliography

* ap Rees, Elfan. "Prototypes And Experimentals No 1: Short R.24/31". ''Air Pictorial'', May 1971, p. 176. * Barnes, Christopher H. and Derek N. James. ''Shorts Aircraft since 1900''. London: Putnam, 1989. .
"The Short "Knuckleduster""
''

Flight Flight or flying is the process by which an object moves through a space without contacting any planetary surface, either within an atmosphere (i.e. air flight or aviation) or through the vacuum of outer space (i.e. spaceflight). This can be a ...

'' 17 July 1935, Vol. XXVIII, No. 1385, pp. 56–58. Retrieved 28 March 2019.

External links

"British Test Angular Ugly Duckling Plane" ''Popular Mechanics'',September 1935
a 1934 ''Flight'' article {{Short Brothers aircraft 1930s British patrol aircraft Flying boats

Knuckleduster Brass knuckles (variously referred to as knuckles, knucks, brass knucks, knucklebusters, knuckledusters, knuckle daggers, English punch, iron fist, paperweight, or a classic) are "fist-load weapons" used in hand-to-hand combat. Brass knuckles ...

Gull-wing aircraft High-wing aircraft Aircraft first flown in 1933 Twin piston-engined tractor aircraft