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

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 wings. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

flying-boat A flying boat is a type of seaplane with a hull (watercraft), hull, allowing it to land on water. It differs from a floatplane in having a fuselage that is purpose-designed for flotation, while floatplanes rely on fuselage-mounted floats for b ...

designed and built by Short to Air Ministry 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 engine. The Saunders-Roe London and the Supermarine Stranraer 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, military outpost (military), outposts, and peoples, "usually created by conquest, and divided between a hegemony, dominant center and subordinate peripheries". The center of the ...

and

Short Sunderland The Short S.25 Sunderland is a British flying boat Maritime patrol aircraft, 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 ...

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 aerospace 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 ...

Supermarine Supermarine was a British aircraft manufacturer. It is most famous for producing the Spitfire fighter plane during World War II. The company built a range of seaplanes and flying boats, winning the Schneider Trophy for seaplanes with three cons ...

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 , 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 behaviour which is to hover ...

engine. The Knuckleduster's straight-sided hull was of all-metal ( Alclad) 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, 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 tr ...

. The wings were designed for high torsional stiffness, each comprising a box-spar with four tapered

stainless steel Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...

tubular booms. Fuel tanks were mounted within the wings; sprung and braced wingtip floats were fitted. The wing surfaces were made 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 A galley is a type of ship optimised for propulsion by oars. Galleys were historically used for naval warfare, warfare, Maritime transport, trade, and piracy mostly in the seas surrounding Europe. It developed in the Mediterranean world during ...

and, further aft, stowage space for

drogue A drogue or 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 (watercraft), hull from becoming side-on to the water waves, waves. A boa ...

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, with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such ...

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 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 (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 modifications incorporated before it returned to Felixstowe in March 1935. In April the Knuckleduster joined 209 Squadron at

RAF Mount Batten Royal Air Force Mount Batten, or more simply RAF Mount Batten, is a former Royal Air Force station and flying boat base at Mount Batten, a peninsula in Plymouth Sound, Devon, England, UK. Originally a seaplane station opened in 1917 as a Royal ...

Plymouth Plymouth ( ) is a port city status in the United Kingdom, city and unitary authority in Devon, South West England. It is located on Devon's south coast between the rivers River Plym, Plym and River Tamar, Tamar, about southwest of Exeter and ...

for service trials alongside the

Stranraer Stranraer ( , in Scotland also ; ), also known as The Toon or The Cleyhole, is a town in Dumfries and Galloway, Scotland, on Loch Ryan and the northern side of the isthmus joining the Rhins of Galloway to the mainland. Stranraer is Dumfries ...

and

London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...

.Air Pictorial May 1971, p.176. This included an appearance at the Royal Air Force display at

Hendon Hendon is an urban area in the London Borough of Barnet, northwest London northwest of Charing Cross. Hendon was an ancient Manorialism, manor and parish in the county of Middlesex and a former borough, the Municipal Borough of Hendon; it has ...

. 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 near to the village of Cosford, Shropshire, England just to the northwest of Wolverhampton and next to Albrighton. It is a training station, home to ...

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 Air force, air and space force of the United Kingdom, British Overseas Territories and Crown Dependencies. It was formed towards the end of the World War I, First World War on 1 April 1918, on the merger of t ...

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 servi ...

* Marine Aircraft Experimental Establishment

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 motion (physics), motion of an Physical object, object through an atmosphere, or through the vacuum of Outer space, space, without contacting any planetary surface. This can be achieved by generating aerodynamic lift ass ...

'' 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 (also referred to as brass knucks, knuckledusters, iron fist and paperweight, among other names) are a melee weapon used primarily in hand-to-hand combat. They are fitted and designed to be worn around the knuckles of the human h ...

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