Miles Libellula

Libellula
Miles M.39B in flight
Role	Fighter (M.35); Bomber (M.39)
Manufacturer	Phillips & Powis/Miles Aircraft
Designer	Ray Bournon and George Miles
First flight	1 May 1942 (M.35)
Primary user	RAF (evaluation only)

The Miles M.35 and M.39 Libellula (from Libellulidae, the taxonomic name for dragonflies) were a pair of tandem wing aircraft built by Miles Aircraft. The first was a fighter-sized aircraft, and the latter a scaled version of a proposed bomber type.

There were two designs, the smaller fighter-sized M.35 and the larger M.39. In the end, only the prototype M.35 and a reduced-scale M.39B were built and tested. Both designs used one wing at the rear of the fuselage and a smaller one at the front in a tandem wing arrangement; the configuration was like that on canard aircraft designs, but with the front wing contributing lift rather than solely acting as a control. The wings were set at different heights – the front at the top of the fuselage and the rear at the bottom on the M.35, and the other way around for the M.39B.

Design and development

The Miles M.39 was a proposal by Miles to meet Air Ministry specification B.11/41 for a fast bomber. Miles had already schemed an idea for an aircraft with exceptional forward visibility in the light of losses of carrier-based aircraft during landing. The M.35 was designed and built as a private venture, and after proving the idea's validity Miles suggested it as the basis for a naval fighter. Miles felt the idea had a lot of merit and put forward a larger design, the M.39, to the Ministry of Aircraft Production.

The Miles Libellula M.35

M.35

The M.35, drawn up in 1941 was powered by a single pusher engine, the pilot sat at the front with the fore wing just behind and level with his head giving a clear view in most directions. The wings and oval section fuselage were of all-wood construction, and the design featured a fixed tricycle landing gear; though an extra tailwheel was included to prevent the propeller striking the ground at rotation during takeoff. Elevators and flaps were hinged at the trailing edge of the front wings; and the rear wings carried ailerons and flaps, as well as a fin with a rudder on each wing tip.^[1] A flying example was built with typical Miles speed, in six weeks. The first flight was on 1 May 1942.

The Miles Libellula M.39B.

M.39

Though it had some problems, the M.35 proved sufficient to show the idea had merits, and the larger M.39 was drawn up. This would be a twin-engined design. The design was prepared to meet Specification B.11/41 which had been issued by the Air Ministry in mid 1942 for a high speed bomber. The specification had been written for the P.1005 proposal by Hawker which was a twin engine (Napier Sabre) fast bomber estimated to achieve 400+ mph at 25,000 ft and deliver a 2,000 lb bomb load over 1,600 miles. ^[2] The P.1005 was cancelled after several delays on behalf of the Air Ministry and before Miles submitted his design to the Ministry.

A scale version at 5/8, the M.39B, was built, flying in 22 July 1943 and showing no "undesirable handling". It coincided with interest by the authorities in unorthodox designs for large aircraft. The rear wing was higher than the forward one to avoid downwash and give ground clearance for the propellers. The M39 design had inboard flaps and outboard ailerons on the rear wing. The front wing had a auxiliary aerofoil/flap/elavator device; it could vary the wing area without changing lift coefficient. Until the intended (three) Powerjets W.2/500 turbojets were available the M.39 would have had two RR Merlin 60 inline or Bristol Hercules VIII radial engines. The M.39 would have a crew of three in a pressurized cabin. As well as the bomb-bay amidships, the M.39 would carry two fixed 20 mm cannon in the wings.

The Ministry agreed a development contract and purchase of the M.39B. In November they ordered a full-size prototype (to carry the serial RR910) but it was not built. Miles continued testing, generating more flight data and submitted an improved M.39 design in early 1944.^[3] The M.39B passed to the Royal Aircraft Establishment at Farnborough in 1944, where it carried the serial SR392. It was damaged in two accidents and repaired each time. but was later broken up with the project’s cancellation.

Specifications (M.35)

Data from The Hamlyn Concise Guide to British Aircraft of World War II^[4]

General characteristics

• Crew: 1
• Length: 20 ft 4 in (6.20 m)
• Wingspan: 20 ft 5 in (6.22 m)
• Height: 6 ft 9 in (2.06 m)
• Wing area: 45 ft² front and 90 ft² rear (4 m², 8.3 m²)
• Empty weight: 1,460 1b (662 kg)
• Loaded weight: 1,850 lb (839 kg)
• Powerplant: 1 × de Havilland Gipsy Major inline piston engine, 130 hp (97 kW)

Performance

• Wing loading: 13.7 lb/ft² (68.2 kg/m²)
• Power/mass: 0.07 hp/lb (0.11 kW/kg)

Specifications (M.39B)

Data from The Hamlyn Concise Guide to British Aircraft of World War II^[5]

General characteristics

• Crew: 1
• Length: 22 ft 2 in (6.76 m)
• Wingspan: front 25 ft 0 in, rear 37 ft 6 in (7.62 m, 11.43 m)
• Height: 9 ft 3 in (2.82 m)
• Wing area: front 61.7 ft², rear 187.5 ft² (6.64 m², 20.16 m²)
• Empty weight: 2,405 lb (1,091 kg)
• Loaded weight: 2,800 lb (1,270 kg)
• Powerplant: 2 × de Havilland Gipsy Major IC air-cooled piston inline engine, 140 hp (104 kW) each

Performance

• Maximum speed: 164 mph (264 km/h)
• Stall speed: 60 mph (97 km/h)
• Rate of climb: 1,100 ft/min (5.59 m/s)
• Wing loading: 11.2 lb/ft² (54.9 kg/m²)
• Power/mass: 0.1 hp/lb (0.16 kW/kg)

See also

Aircraft of comparable role, configuration and era

• Curtiss-Wright XP-55 Ascender
• Kyushu J7W
• Mikoyan-Gurevich MiG-8
  

Related lists

• List of experimental aircraft
• List of aircraft of the United Kingdom in World War II
  

References

Notes

1. ^ Bridgman (Jane's) 1998, p. 131.
2. ^ Buttler p83
3. ^ Buttler p87
4. ^ Mondey 2002, p. 174.
5. ^ Mondey 2002, p. 175.

Bibliography

• Amos, Peter and Don Lambert Brown. Miles Aircraft Since 1925, Volume 1. London: Putnam Aeronautical, 2000. ISBN 0-85177-787-0.
• Bridgman, Leonard (ed.) Jane's fighting aircraft of World War II. London: Crescent, 1998. ISBN 0-517-67964-7
• Brown, Don Lambert. Miles Aircraft Since 1925. London: Putnam & Company Ltd., 1970. ISBN 0-37000-127-3.
• Brown, Eric. "The Lovelorn Libellula." Air Enthusiast Five November 1977-February 1978. Bromley, Kent, UK: Pilot Press Ltd., 1977.
• Buttler, Tony. British Secret Projects Fighters & Bombers, 1935-1950. Hinckley: Midland Publications, 2004. ISBN 978-1-85780-179-8.
• Mondey, David. The Hamlyn Concise Guide to British Aircraft of World War II. London: Chancellor Press, 2002. ISBN 1-85152-668-4.
• "The Miles 'Dragonflies'" Aeroplane Monthly, June 1973. London: IPC Media Ltd. ISSN 0143-7240.

External links

• "M.35 Libellula". Miles Aircraft History site. 13 January 2006. http://replay.waybackmachine.org/20060113150748/http://www.miles-aircraft.com/M.35_and_m.39b_libellula.html. Retrieved 29 March 2011. 
• Teeuwen, Jaap. "Miles M.35". British Aircraft of WW2. www.jaapteeuwen.com. http://replay.waybackmachine.org/20080820080850/http://www.jaapteeuwen.com/ww2aircraft/html%20pages/MILES%20M35.htm. Retrieved 29 March 2011. 
• Teeuwen, Jaap. "Miles M.39B". British Aircraft of WW2. www.jaapteeuwen.com. http://replay.waybackmachine.org/20080703165346/http://www.jaapteeuwen.com/ww2aircraft/html%20pages/MILES%20M39B.htm. Retrieved 29 March 2011. 
• Miles Tandem Monoplanes Flight 1944
• pictures of Miles Tandem Monoplanes - Flight 1944