Miles M.39B (Libellula)

History

The M.39 "Libellula" was conceived by the Miles Aircraft Company in the early 1940s when World War II (1939-1945) raged. The original concept was to reduce the complexity of landing aircraft on the carrier deck, where visibility is largely obscured by forward engines and large main aircraft. A new approach was taken, designed to reduce the risks involved, and this became a "tandem wing" arrangement that eventually encompassed some of Myers' concepts during the war.

However, neither concept came to fruition through a series production contract, although the M.39B was built and flown as a prototype.

In general, the design with which Miles made this effort is known as the "Libellula," a taxonomic surname for dragonflies (no doubt a reference to the twin-blade main plane that Miles used).

The original work on this theme comes from the M.35 product, which is more or less a technology demonstrator for a single-seat naval fighter. It was modeled on a private project by Myers with a tandem wing arrangement to re-evaluate the Center of Gravity (CoG) seen in traditional military aircraft (main aircraft at the front and tail at the rear).

The tandem wing approach allows for a greater range of centres of gravity between the two main aircraft in the game, and could theoretically have some inherent advantages - shorter fuselage and more enclosed onboard storage span (and less weight), less complexity of the wings, as there is no need to use the wing folding mechanism, and control is improved by "doubling" the control surfaces along the pair of wings.

Engineer Miles is back with the M.35 in just six weeks. Powered by a 130-horsepower de Havilland Gypsy Major inline air-cooled engine, the aircraft has a front main aircraft wingspan of 20 feet and rear main aircraft wingspan of 20.5 feet. The overall length is 20.3 feet and the maximum weight reaches 2,000 pounds.

The cockpit remains at the very forward end of the fuselage, providing excellent visibility. The main wing of the front wing is a shoulder-mounted design with a straight line design, while the main wing of the rear wing is a low-mounted, swept-back design. The vertical tail is attached to the tip of the rear main aircraft. The engines are buried in the rear of the fuselage and are arranged in a "propeller" configuration. A pseudo-trike undercarriage was installed, although the fourth leg was always behind to protect the rear of the aircraft.

In testing, the engine proved to be dynamic, with longitudinal control turned off. Nonetheless, the design demonstrates some unorthodox arrangements that will aid future work in the field.

The piece was further developed into a new 5/8 scale design and named M. 39B. The aircraft will serve as a single-seat demonstrator, powered by two air-cooled in-line de Havilland Gypsy primary IC engines of 130 hp each - these are powered by outboards suspended below each rear wing main aircraft The cabin is presented. The former main aircraft is now positioned low on either side of the cockpit.

The fuselage is given a finely contoured shape from nose to tail. Tricycle landing gear installed - now in the traditional sense.

Due to the larger project range of the M. 39B, its size has also increased accordingly. The wings now reach 25 feet at the front and 37.5 feet at the rear. The overall length is 22.3 feet, and the maximum weight increases to 3,200 pounds.

After being built and tested, the M. 39B was capable of reaching speeds of 166 miles per hour, with twin engines and with tandem wings. The first flight of the M. 39B took place on July 22, 1943.

A dorsal fin was later added to the rear of the fuselage to complete the M.39B's signature three-fin appearance.

By September 1943, all work on the M.35 and M.39B aircraft was a private endeavor. Since then, the British Air Force has decided to offer Miles a formal development contract. Shortly thereafter, Miles attempted to pique the interest of the United States Army Air Forces (USAAF), who were already considering a homebrew Curtis XP-55 "Ascender" with a similar tandem wing, thruster engine configuration designed to use Fighter.

The USAAF responded by being generally disinterested in the Miles product, as the XP-55 had its own problems - especially with stall and recovery. With the U.S. program and a total of three aircraft built, only flight tests were performed.

The M.39B has received an assessment from the Royal Aircraft Corporation (RAE) and the problem has been there from the start. A new landing gear had to be installed, and several incidents kept the machine in constant repair and prevented useful flight operations.

Overall, despite the unusual layout, the flight characteristics of the aircraft are considered fairly normal. Landing and takeoff require some changes to the usual routine, but that's forgivable. Stall and recovery as expected.

As early as 1941, the RAF issued a new specification (B. 11/41) for medium high performance bombers at medium and high altitudes. Myers responded by offering his M. 39 project, a revised version of the M. 39B with a crew of 3 in a pressurized cockpit.

Power comes from 2 Rolls-Royce Merlin 61 series inline engines or 3 Power Jets W. 2/500 gas turbine engines. The front wingspan has been significantly increased to 37.5 feet and the rear wingspan is 55.8 feet. Overall length increased to 35.9 feet and maximum weight increased to 26,750 pounds.

The recommended cruise speed is 360 mph, and armament includes 2 x 20mm cannons at the root of the wings (one per wing), carrying up to 6,000 lb bombs through an internal bomb bay in the center of the fuselage.

de Havilland DH finally meets the B. 11/41 specification. 99 "Vampires". Hawker P. 1005 is also sometimes in operation.

The prototype M.39 high-speed bomber was ordered under a contract signed in November 1943, but was never built. The RAF bomber requirements were met elsewhere, and the M. 39 project ended with the M. 39B data acquisition aircraft.

Although the M.39B survived the war, it only lasted until it was scrapped in 1948.

The last proposal related to the Libellula project is M.63. The aircraft was instead equipped with three cluster jet engines in the aft fuselage, eliminating the wing-mounted, strut-driven engine nacelles of the original design (which also served as the central dorsal fin in the M 39B).

The result is a more streamlined variant that retains all the capabilities of the M. 39 high-speed bomber, complete with a courier aircraft - although even this suggestion was broken by Miles.

Specification

Basic

Production

Roles

Dimensions

Weight

Performance

Performance

Armor

Changes