The Miles M.20 was an experimental fighter developed during the early stages of World War 2.
It was developed against the backdrop of the battle of Britain. The meeting between the Miles design staff and the Air Ministry took place on 13th July 1940. The Air Ministry demanded that the prototype be completed within three months of this date and it was only when Miles Aircraft agreed to this that contract B140247/40 was placed for one prototype.
To ensure rapid design and construction, it was decided to;
- Use wooden construction (wood working labour was readily available).
- Fit a non-retracting undercarriage.
- Delete all hydraulics (hydraulic equipment was in short supply).
- Use standard parts. For example, Hurricane gun mounting fittings and Miles Master flying controls.
- Use an existing power plant. The fuselage was designed to fair in with a standard Bristol Beaufighter MkII's Merlin XX power plant.
The fighter was covered by specification F.19/40 and so was required to have a maximum speed not less than 350 mph at 21,000ft and a service ceiling of 32,000ft despite these severe austerity measures.
Miles did it. The prototype ordered flew on 15th September 1940. It was later given the serial AX834 and it was this aircraft that ended up in a gravel pit after brake failiure.
Despite the thick wing (21% thickness/chord ratio) Miles managed to reduce drag with a very slippery surface. They also made construction as simple as possible,the fuselage skinning was made very simple by avoiding any double curvature for example.
Archibald Sinclair effectively killed the M.20 in a letter of 30th December 1940 in which he stated that the M.20's performance was "not good enough for day use". However, he did hold out the possibility of the M.20 being used as a disposable convoy protection fighter, with small wheels projecting beneath the fuselage instead of the normal fixed undercarriage to make landings in the sea safer. A second prototype was built to this end, the first having overshot the runway and crashed into a gravel pit in February 1941. The role was eventually filled by the "Hurricat".
The prototype was then altered to meet specification N.1/41 issued in July 1941 for a naval fighter, which could be used from catapults on CAM ships (Catapult Aircraft Merchantmen). However these ships had no flight decks so the aircraft had to be ditched into the sea after just one mission. In April 1942 the aircraft went to A&AEE at Boscombe Down for assessment. It got a pretty good report, though a strong swing to the left on take off, which could not be corrected if allowed to develop, and heavy controls with overbalanced ailerons were criticised. The fixed undercarriage was considered very dangerous in the event of a ditching, which was not ideal for a naval fighter.
The potential roles for the aircraft were filled by other types so it never entered production. The prototype (DR616) was struck off charge on 22 May 1942 and broken up in November of that year.
- Max speed: 333 mph (536 km/h) at 20,600 ft (6 280 m).
- Initial climb; 3,200 ft/min (16,25 m/sec).
- Normal range: 550 mls (885 km).
- Empty weight: 5,870 lb (2 663 kg).
- Loaded Weight: 7,7581b (3 519 kg).
- Span: 34 ft 7 in (10,54 m).
- Length: 30ft 1 in (9,17m).
- Height: 12ft 6in (3,81 m).
- Wing area: 234 sq ft (21, 74 m2),