Miles M.20

The Miles M.20 was a Second World War fighter developed by Miles Aircraft in 1940. It was designed as a simple and quick-to-build "emergency fighter" alternative to the Royal Air Force's Spitfires and Hurricanes should their production become disrupted by bombing expected in the anticipated German invasion of England. Due to the subsequent shifting of the German bombing effort after the Battle of Britain towards British cities in what became known as The Blitz, together with the dispersal of British fighter manufacturing, the Luftwaffe's bombing of the original Spitfire and Hurricane factories did not seriously affect production, and so the M.20 proved unnecessary and the design was not pursued.

M.20
Second prototype of the Miles M.20
Role Lightweight fighter
Manufacturer Miles Aircraft
Designer Walter G. Capley
First flight 15 September 1940
Primary users Royal Air Force (intended)
Fleet Air Arm (intended)
Number built 2 prototypes
Developed from Miles Master

Design and development

At the outbreak of the Second World War in September 1939, Miles Aircraft began work on a single-engined fighter to supplement the RAF's Spitfires and Hurricanes. A wooden mock-up of the design, the M20/1, was inspected by Sir Kingsley Wood, the Secretary of State for Air, but no orders followed.[1] Following the outbreak of the Battle of Britain in July 1940, the Royal Air Force was faced with a potential shortage of fighters. To meet the Luftwaffe threat, the Air Ministry commissioned Miles to design a simple easy-to-build fighter to specification F.19/40. This became the Miles M.20/2. Nine weeks and two days later the first prototype flew.[2][1]

To reduce production time the M.20 employed all-wood construction and used many parts from the earlier Miles Master trainer, lacked hydraulics, and had spatted fixed landing gear. The fixed undercarriage freed space and payload sufficient for twelve .303 Browning machine guns and 5000 rounds, and 154 Imperial gallons (700 litres) of fuel (double the range and ammunition capacity of the Hawker Hurricane and Supermarine Spitfire).[3] The M.20 was fitted with a bubble canopy for improved 360-degree vision.

In line with a design philosophy emphasising simplicity, speed and re-using available components, the engine was a Rolls-Royce Merlin XX "power egg" identical to those used on Merlin-powered Avro Lancasters and Bristol Beaufighters. This conferred flight performance that fell between those of Britain's two frontline fighters.

Testing and evaluation

The first prototype, with the B-class serial U-9 first flew on 15 September 1940,[4] and was tested at the A & AEE under the military serial number AX834 against Specification F.19/40. Armed with eight .303 Browning machine guns like the Hurricane, the M.20 prototype was faster than the Hurricane but slower than Spitfire types then in production, but carried more ammunition and had greater range than either. As the Luftwaffe had been defeated over Britain, the need for the M.20 had vanished and the design was abandoned without entering production. The first prototype was scrapped at Woodley.

A second prototype, U-0228 (later DR616) was built to Specification N.1/41 for a Fleet Air Arm shipboard fighter, equipped with an arrestor hook and catapult launch points. It first flew on 8 April 1941.[5] This variant could be launched by catapult aircraft merchant ships which lacked flight decks so the aircraft were to be ditched after their mission, and to facilitate this the undercarriage could be jettisoned. However, obsolete Hurricanes were modified to fill this role, which rendered a shipboard variant of the M.20 unnecessary. Consequently, this prototype was also scrapped.

Specifications (M.20/4)

Data from The British Fighter since 1912,[6] Miles Aircraft since 1925[7]

General characteristics

  • Crew: 1
  • Length: 30 ft 1 in (9.17 m)
  • Wingspan: 34 ft 7 in (10.54 m)
  • Height: 12 ft 6 in (3.81 m)
  • Wing area: 234 sq ft (21.7 m2)
  • Aspect ratio: 5.1
  • Airfoil: root: NACA 23021; tip: NACA 23009[8]
  • Empty weight: 5,870 lb (2,663 kg)
  • Max takeoff weight: 7,758 lb (3,519 kg)
  • Fuel capacity: 154 imp gal (185 US gal; 700 l) fuel ; 8.5 imp gal (10 US gal; 39 l)
  • Powerplant: 1 × Rolls-Royce Merlin XX V-12 liquid-cooled piston engine, 1,260 hp (940 kW) at 3,000 rpm
  • Propellers: 3-bladed Rotol constant-speed propeller

Performance

  • Maximum speed: 333 mph (536 km/h, 289 kn) at 20,600 ft (6,279 m) combat load
350 mph (304 kn; 563 km/h) clean at 20,600 ft (6,279 m)
  • Stall speed: 80 mph (130 km/h, 70 kn) flaps down
101 mph (88 kn; 163 km/h) flaps up
  • Range: 550 mi (890 km, 480 nmi) / 2 hour duration - normal
870 mi (756 nmi; 1,400 km) / 5 hours 12 minutes duration - absolute maximum
  • Endurance: 5 hours 12 minutes at 9,000 ft (2,743 m)
  • Service ceiling: 31,400 ft (9,600 m)
  • Absolute ceiling: 35,500 ft (10,820 m)
  • Rate of climb: 3,200 ft/min (16 m/s)
  • Time to altitude: 20,000 ft (6,096 m) in 9 minutes 36 seconds
  • Wing loading: 33.2 lb/sq ft (162 kg/m2)
  • Take-off run: 810 ft (247 m) with 30° flap
  • Take-off distance to 50 ft (15 m): 1,350 ft (411 m) with 30° flap

Armament

See also

Related development

Aircraft of comparable role, configuration, and era

Related lists

References
  1. Brown Aeroplane Monthly April 1976, pp. 207–208.
  2. Bridgeman 1946, p. 133.
  3. Mondey, David (1982). Hamlyn Concise Guide to British Aircraft of World War II. Chancellor Press. p. 170. ISBN 1-85152-668-4.
  4. Jarrett 1992, p.55.
  5. Jarrett 1992, p. 57.
  6. Mason 1992, pp. 292–293.
  7. Brown, Don L. (1970). Miles Aircraft since 1925 (1st ed.). London: Putnam & Company Ltd. pp. 172-177. ISBN 0-370-00127-3.
  8. Lednicer, David. "The Incomplete Guide to Airfoil Usage". m-selig.ae.illinois.edu. Retrieved 16 April 2019.

Bibliography
  • Bridgeman, Leonard. "The Miles M.20." Jane's Fighting Aircraft of World War II. London: Studio, 1946. ISBN 1-85170-493-0.
  • Brown, Don. "Last-ditch defender". Aeroplane Monthly, Vol. 4, No. 4, April 1976, pp. 207–211.
  • Green, William. Warplanes of the Second World War, Fighters, Vol. 2. London: Macdonald, 1961.
  • Jarrett, Philip. "Nothing Ventured..." Part 21. Aeroplane Monthly, Volume 20 No. 1, Issue 225, January 1992, pp. 54–60. London: IPC. ISSN 0143-7240.
  • Mason, Francis K. The British Fighter since 1912. Annapolis, Maryland: Naval Institute Press, 1992. ISBN 1-55750-082-7.
  • Mondey, David. The Hamlyn Concise Guide to British Aircraft of World War II. London: Chancellor Press, 2002. ISBN 1-85152-668-4.
  • Swanborough, Gordon. British Aircraft at War, 1939–1945. East Sussex, UK: HPC Publishing, 1997. ISBN 0-9531421-0-8.
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