Miles M.52

The Miles M.52 was a British supersonic research aircraft project which was undertaken in top secret between 1942 and 1945. The Air Ministry later cancelled the project for reasons that remain controversial to this day.

Design and development

The British Miles Aircraft company was responsible for a range of aircraft right back to the early days of flight, but their name is relatively unknown, not being associated with any of the great classic designs. In 1942, the Air Ministry and the Ministry of Supply approached Miles with a top-secret contract, E.24/43, for a jet powered research plane designed to reach supersonic speeds. The contract called for an "aeroplane capable of flying over 1,000 mph (1,600 km/h) in level flight, over twice the existing speed record, and climb to 36,000 feet (11,000 m) in 1.5 minutes."

A huge number of advanced features were incorporated into the resulting M.52 design, many of which hint at a detailed knowledge of supersonic aerodynamics which, due to the war, took years to become public. In particular, the design used very thin wings for low drag (see wave drag) and "clipped" the tips to keep them clear of the conical shock wave generated by the nose of the aircraft. With no other sources on supersonic flight Miles had turned to the known area of ballistics.

The fuselage had the minimum cross-section allowable around the centrifugal engine with fuel tanks in a saddle over the top. Another critical addition was the use of an "all-moving tail," key to supersonic flight control, which contrasted with traditional designs that used a two-piece stabilizer/elevator design. This tail was tested on a M.3b Falcon Six light aircraft at RAE in April 1945.

One of the Vickers models undergoing supersonic wind-tunnel testing at the Royal Aircraft Establishment (RAE) c.1943

The design was to be powered by Frank Whittle's latest design, the Power Jets W.2/700. It incorporated a reheat jetpipe - now known as an afterburner - to give extra power. Burning extra fuel in the tailpipe avoided overheating the metal of the turbine blades and made use of the unburnt oxygen in the exhaust. In order to supply more air to the afterburner than could move through the fairly small engine, a fan, powered by the engine, was installed in front of the assembly and blew air around the engine in ducts, essentially an early turbofan engine.

Finally the design added another critical element, the use of a shock cone in the nose to slow the incoming air to the subsonic speeds needed by the engine. This design feature became common on many postwar aircraft such as the English Electric Lightning and MiG 21. Supersonic heating was not completely understood at the time, so the M.52 was built using stainless steel instead of duraluminum.

The pilot would have sat in a small cockpit inside the shock cone in the nose of the aircraft, and in an emergency the entire area would be thrown free of the aircraft using explosive bolts. The pilot would then wait for the cockpit to slow, then exit and parachute to safety. The ability to exit the capsule was a serious concern however, since it was not stable on its own at supersonic speeds, and likely would have tumbled, possibly breaking up.

There were many changes during development due to the uncertain nature of the task. Initially a very thin biconvex wing was to be used. This would have been made thicker if required later with additional sections added on. The overseeing committee was concerned that the biconvex wing would not give sufficient altitude for testing the aircraft in a dive.

As the project progressed an increase in total weight led to concerns that power would be insufficient and rocket assistance or extra fuel tanks were considered.

Miles requested the use of a Supermarine Spitfire, then the fastest aircraft available to test the tailplane, this was not provided and features such as the thin wing and the innovative tailplane design incorporating the "all-moving tailplane" were tested on the Miles "Gillette Falcon" in 1943.

Operational history

Prototypes

In 1944, design work was considered 90% complete and Miles was told to go ahead with the construction of three prototype M.52s. Later that year, the Air Ministry signed an agreement with the United States to exchange high-speed research and data. The Bell Aircraft company was given all of the drawings and research on the M.52, but the U.S. reneged on the agreement and no data was forthcoming in return. Unknown to Miles, Bell had already started construction of a rocket-powered supersonic design of their own, but were battling the problem of control. A variable-incidence tail appeared to be the most promising solution; the Miles data seemed to confirm this. Later, under manned flight, pilot Chuck Yeager would verify it experimentally, and all subsequent supersonic aircraft would either have an all-flying tailplane or a delta wing.

Cancellation

At the close of the Second World War, the first of the three M.52s was 82% completed, with test flights only a few months away. However, in February 1946, the new Labour government introduced a dramatic budget cut, and the Director of Scientific Research, Sir Ben Lockspeiser, cancelled the project. The actual reasons for the cancellation of the Miles M.52 was that Britain was utterly bankrupt post-Second World War and couldn't afford the programme; Miles still required several thousand pounds more to complete the work. Among the other factors contributing were the doubts about pilot safety, as well as some German research that seemed to point to swept wings being desirable at supersonic speeds.

Subsequent work

Instead the government instituted a new programme involving expendable, pilotless, rocket-propelled missiles. The design was passed to Barnes Wallis at Vickers Armstrong, and the engine development took place at the RAE. The result was a 1/3 scale model of the original M.52 design, powered by an Armstrong Siddeley Beta rocket engine and radio controlled.

The first launch took place on 8 October 1947, but the rocket exploded shortly after launch. Only days later, the Bell X-1 broke the sound barrier and there was a flurry of denunciation of the Labour policies in research and development with the Daily Express taking up the cause for the restoration of the M.52 programme, but to no effect. On 10 October 1948, a second rocket was launched, and a speed of Mach 1.38 was obtained. But, instead of diving into the sea as planned, the model failed to respond to radio commands and was last observed (on radar) heading out into the Atlantic. At that point, further work was cancelled.

1,000 mph

The 1000 mph speed specified for the M.52 was eventually achieved when the Fairey Delta 2 WG774 became the first aircraft to reach and surpass it. On 10 March 1956, WG774 broke the World Air Speed Record raising it to 1,132 mph (1811 km/h).

Specifications (M.52)

Data from

General characteristics

• Crew: 1

Performance

See also

Aircraft of comparable role, configuration, and era

• Bell X-1
• Silbervogel

References

Bibliography

• Amos, Peter and Don Lambert Brown, . Miles Aircraft Since 1925, Volume 1. London: Putnam Aeronautical, 2000. ISBN 0-85177-787-0.
• Brown, Don Lambert. Miles Aircraft Since 1925. London: Putnam & Company Ltd., 1970. ISBN 0-37000-127-3.
• Brown, Eric. "Miles M.52: The Supersonic Dream." Air Enthusiast Thirteen, August-November 1980. ISSN 01443-5450.
• Faster than Sound. NOVA (PBS) documentary, first broadcast 14 October 1997.
• McDonnell, Patrick. "Beaten to the Barrier." Aeroplane Monthly Volume 26, No. 1, Issue 297, January 1998.
• Wood, Derek. Project Cancelled. Indianapolis: The Bobbs-Merrill Company Inc., 1975. ISBN 0-672-52166-0.
• Yeager, Chuck et al. The Quest for Mach One: A First-Person Account of Breaking the Sound Barrier. New York: Penguin Studio, 1997. ISBN 0-670-87460-4.

External links

• Faster than Sound - Nova documentary
• transcript of the Nova programme
• Jets45 Histories
• Eric "Winkle" Brown talks about the M.52 in 2008