Miles M.35 Libellula

The Miles M.35 or Miles Libellula (from Libellulidae, the taxonomic name for a family of dragonflies) was a tandem wing research aircraft built by Miles Aircraft as a precursor to a proposed naval carrier fighter.

Design and development
Carrier borne combat aircraft are at a disadvantage when compared to land-based equivalents as they require wing-folding systems, which increase the aircraft's weight at the expense of payload. At the time, adaptions of single-engined tail-dragger land-based aircraft typically had poor visibility when landing. At some time in 1941, Miles became aware of the high accident rates for carrier landings and began private venture work on unorthodox configurations that might solve the visibility problem and also the complications of folding wings required for storage of ship-borne aircraft.

While contemplating these problems, George Miles visited the Aeroplane and Armament Experimental Establishment at RAF Boscombe Down, where he saw the Westland-Delanne tandem wing Lysander, which had a second wing with tip rudders in place of the conventional vertical stabilizer and tailplane arrangement. George Miles realised that a tandem-wing fighter could be built to fit onto carrier elevators without folding and that the pilot could be seated in the nose, giving an excellent view for carrier landings. Among the solutions considered, the tandem wing configuration appeared to Miles to be the answer provided it was "aerodynamically feasible".

Advantages of a tandem-winged carrier fighter would include: small size, manoeuvrability, excellent visibility, reduced weight and reduced drag. Rather than go through the process of submitting an unorthodox design for official consideration, Miles decided to build and fly a mock-up. Miles tasked Ray Bournon with designing a small single-engined single-seat aircraft, the Miles M.35. Design and construction was completed in six weeks. The result was a small wooden aircraft with a high-set front wing and low-set rear wing, fixed tricycle undercarriage, and pusher propeller, with the engine in the rear of the fuselage and the pilot sitting in the front of the fuselage.

The front wing was moderately tapered with a straight leading edge, while the rear wing was in three parts: an unswept centre section, clearing the propeller and supporting the main undercarriage legs, and outer sections from about ¼ span swept back at approximately 30º, supporting large end-plate fins at the tips. The box-like fuselage connected all the components and carried the engine, fuel and cockpit as well as the nose undercarriage.

Operational history
Flight trials of the M.35 were to commence in 1942, but Miles' chief test pilot was reluctant to take off in the aircraft, whereupon George Miles took over himself. The M.35 proved to be extremely reluctant to take-off; eventually Miles discovered that if the throttle was closed sharply whilst at speed the little aircraft leapt into the air. The initial flight on 1 May 1942 was not a success, with the aircraft almost uncontrollable due to an incorrect centre of gravity, but Miles managed to land it in one piece. Later flights were more successful after ballasting the aircraft correctly, proving that the tandem-wing layout could be useful as a naval fighter. Further flying was carried out in support of Miles other tandem-wing projects.

Miles immediately submitted a proposal for a naval fighter based on the arrangement - which they called Libellula - to the Admiralty and the Ministry of Aircraft Product. Having built the M.35 in secret without official authority the company was castigated by the Ministry of Aircraft Production which, along with the Admiralty, rejected the proposed fighter. Miles were so encouraged by the results from the M.35 that they drew up a bomber design on the same principles that was then submitted on July 1942 to meet the requirements of specification B.11/41 and started work on a scale version - the M39B.