Miles M.52 - WikiHQ

The Miles M.52 was a turbojet-powered supersonic research aircraft project designed in the United Kingdom in the mid-1940s. In October 1943, Miles Aircraft was issued with a contract to produce the aircraft in accordance with Air Ministry Specification E.24/43. The programme was highly ambitious for its time, aiming to produce an aircraft capable of a speed of at least during level flight, and involved a very high proportion of cutting-edge aerodynamic research and innovative design work.

Until 1945 all work on the project was undertaken with a high level of secrecy. In February 1946, the programme was terminated by the new Labour government of Clement Attlee, seemingly due to budgetary reasons as well as the disbelief of some ministry officials regarding the practicality of supersonic aircraft. In September 1946 the existence of the M.52 project was revealed to the general public, leading to criticism of the decision and calls for an official explanation of why the project had been terminated. The Ministry of Supply controversially decided to investigate the design with six different configurations of wing and control surfaces, but as a series of unmanned rocket-powered 30 per cent scale models instead of a manned full-scale aircraft. The contract was awarded to Vickers rather than Miles. The models were air-launched from a modified de Havilland Mosquito mother ship.

A model with the M52 configuration of wing and control surfaces achieved Mach 1.38 in controlled transonic and supersonic level flight, a unique achievement at that time and which provided "some validation of the aerodynamics of the M.52 upon which the model was based". Prior to the flight the decision had already been made to terminate the programme. Work on the afterburning version of the Power Jets W.B.2/700 turbojet was also cancelled, and Power Jets was incorporated into the National Gas Turbine Establishment. According to senior figures at Miles, the design and the research gained from the M.52 was shared with the American company Bell Aircraft, and that this was applied to their own Bell X-1, the experimental aircraft which broke the sound barrier.

Development

Background

Prior to the Second World War, conventional wisdom throughout the majority of the aviation industry was that manned flight at supersonic speeds was next to impossible, mainly due to the apparently insurmountable issue of compressibility. During the 1930s, few researchers and aerospace engineers chose to explore the field of high-speed fluid dynamics; notable pioneers in this area were the German aerospace engineer Adolf Busemann, British physicist Sir Geoffrey Taylor, and British engine designer Sir Stanley Hooker. While Germany gave considerable attention to exploring and implementing Busemann's theories on the swept wing and its role in drag-reduction during high-speed flight, both Britain and the United States largely ignored this research. It was only by 1944 that information about the rocket-propelled Messerschmitt Me 163 and the jet-propelled Me 262, both with swept wings, caused attitudes on its merits begin to change. By then the British Air Ministry had already launched a research programme of its own.

In Autumn 1943, the Air Ministry issued Air Ministry Specification E.24/43 calling for a jet-powered research aircraft capable of flying at over in level flight (over twice the existing speed record ) and the ability to climb to in 1.5 minutes. The E.24/43 has been described as being "the most far-sighted official requirement ever to be issued by a Government department...a complete venture into the unknown with engine, airframe, and control techniques beyond anything remotely considered before".

The Miles Aircraft company had its beginnings in the 1920s and had made a name for itself during the 1930s by producing affordable ranges of innovative light aircraft, perhaps the best known amongst these being the Miles Magister and Miles Master trainers, large numbers of both types seeing extensive use by the RAF for pilot training. Although the company's products were relatively low-technology aircraft, , Miles had a good relationship with the Air Ministry and the Royal Aircraft Establishment (RAE), and had submitted several proposals for advanced aircraft in response to ministry specifications. The decision to involve the company has been alleged to have been partially in order to resolve a dispute about a separated contract that allegedly had been mishandled by the Ministry of Aircraft Production;

Another critical addition was the use of a power-operated stabilator, also known as the all-moving tail or flying tail, a key to supersonic flight control which contrasted with traditional elevators hinged to tailplanes (horizontal stabilizers). Conventional control surfaces became ineffective at the high subsonic speeds then being achieved by fighters in dives, due to the aerodynamic forces caused by the formation of shockwaves at the hinge and the rearward movement of the centre of pressure, which together could override the control forces that could be applied mechanically by the pilot, hindering recovery from the dive. A major impediment to early transonic flight was control reversal, the phenomenon which caused flight inputs (stick, rudder) to switch direction at high speed; it was the cause of many accidents and near-accidents. An all-flying tail is required for non-delta winged aircraft to pass through the transonic region to supersonic speeds without a loss of control. The M.52 was the first instance of this solution.

thumb|left|One of the Vickers models undergoing supersonic wind-tunnel testing at the [[Royal Aircraft Establishment (RAE) c. 1946]]

An initial version of the aircraft was to be test-flown using Frank Whittle's latest engine, the Power Jets W.2/700. The calculated landing speed of (comparable with modern fighters but high for that time) combined with its relatively small undercarriage track was another concern; however, this arrangement was accepted.

Design

In order to achieve what was at the time previously unachievable speeds a very high number of advanced features were incorporated into the design of the M.52; many of these were the result of detailed study and acquired knowledge of supersonic aerodynamics. Wood summarises the qualities of the M.52's design as possessing "all the ingredients of a high-performance aircraft of the late fifties and even some of the early sixties". The fuselage had a 5 foot diameter with an annular fuel tank around the engine.

American influence upon the design further contributed to the shape of the wings. While conventional supersonic aircraft feature swept wing designs, airframes from the US largely focused on long range and heavy payload carrying capabilities. The airfoil as well as the general shape of the wing still provided minimal drag across a variety of different speeds, lending itself useful to the design of the DARPA XS-1.

The Power Jets W.2/700 turbojet engine was intended to be the first powerplant for the M.52. Initial aircraft would have been powered by a less-capable 'interim' model of the W.2/700 and thus be limited to subsonic speeds only; it did not feature either the afterburner or the additional aft fan that were to be present on the projected more advanced version with which later-built M.52s would have been equipped. In addition to the W.2/700 engine, a centrifugal-flow jet engine, designs were prepared for the M.52 to be fitted with a variety of different engines and types of propulsion, including what would become the newer Rolls-Royce Avon axial-flow jet engine, and a liquid-fuel rocket motors. however, 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, having adopted a conventional tail for their aircraft, were battling the problem of control. A variable-incidence tail appeared to be the most promising solution; the Miles and RAE tests supported this conclusion. Later, following the conversion of the aircraft's tail, pilot Chuck Yeager practically verified these results during his test flights, and all subsequent supersonic aircraft would either have an all-moving tailplane or a delta wing.

Testing

During 1943 a single Miles M.3B Falcon Six light aircraft, which had been previously used for wing tests by the RAE, was provided to Miles for purpose of performing low-speed flight testing work on the project. A full size wooden model of the M.52 wing, test instrumentation, and a different undercarriage were fitted to this aircraft. By this point, the postwar Labour government, headed by Clement Attlee, had implemented dramatic budget cuts in various areas, which may have provided an inducement for the cancellation of the M.52, which was projected to involve considerable cost. According to Wood, "the decision not to go ahead was purely a political one made by the Attlee Government".

In February 1946, around the same time as the termination of the M.52's development, Frank Whittle resigned from Power Jets, stating that this was due to his disagreement with official policy. At the point of cancellation, the first of the three M.52s had been 82 per cent completed and it had been scheduled to commence the first test flights within only a few months. Lockspeiser's role in cancelling the M.52 became public knowledge, leading to his decision being derided in the press as "Ben's blunder".

It was not until February 1955 that another official reason for the M.52's cancellation emerged; a white paper issued that month stated that "the decision was also taken in 1946 that, in light of the limited knowledge then available, the risk of attempting supersonic flight in manned aircraft was unacceptably high and that our research into the problems involved should be conducted in the first place by means of air launched models." This same paper acknowledged that the termination decision had seriously delayed the advancement of aeronautical progress by Britain. It has since been widely recognised that the cancellation of the M.52 was a major setback in British progress in the field of supersonic design.

In 1947, Miles Aircraft Ltd entered receivership and the company was subsequently re-structured; its aircraft assets including the design data for the M.52 were acquired by Handley Page.

Subsequent work

Instead of a revival of the full-scale M.52, the government decided to institute a new programme involving expendable, pilotless, rocket-propelled missiles; it was envisioned that a total of 24 flights would be performed by these models, which would explore six different wing and control surface configurations, including alternative straight wing and swept wing arrangements. Wood referred to the failure to revive the full-scale aircraft as "at one stroke Britain had opted out of the supersonic manned aircraft race". The contract for the expendable missiles was not issued to Miles but to Vickers-Armstrongs, whose design team was led by noted British engineer and inventor Barnes Wallis. While the base design work was conducted by Wallis' team, engine development was performed by the RAE itself. The product of these efforts was a 30 per cent scale radio-controlled model of the original M.52 design, powered by a single Armstrong Siddeley Beta rocket engine, fuelled by a mix of high-test peroxide. On 10 October 1948, a second rocket was launched, and the speed of Mach 1.38 was obtained in stable level flight, a unique achievement at that time. 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. Following that successful supersonic test flight, further work on this project was cancelled, Wood commented of the model programme: "with the money thus wasted the piloted M.52 could have been completed and flown and a great store of invaluable information obtained...the pilot was shown to be essential for any worthwhile development process and a well designed test-bed aircraft to be a sine qua non for full-scale knowledge".

Many important design principles that were incorporated in the M.52 did not reappear until the mid- to late 1950s, with the development of truly supersonic aircraft such as the Fairey Delta 2, and the English Electric P.1 which became the English Electric Lightning. And the X-1, D-558-2, F-100, F-101, F-102, F-104, Mig-19 etc. in the 40s and early 50s. The wing design of the M.52 was similar to the supersonic Wasserfall German rocket. Both of those aircraft were developed in response (initially) to requirement ER.103 of 1947, informed by the knowledge gained from the M.52 aircraft and missile research projects together with German experimental data.

Specifications (M.52)

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References

Notes

Bibliography

Amos, Peter. Miles Aircraft – The Early Years: The Story of F G Miles and his Aeroplanes, 1925–1939. Tonbridge, Kent, UK: Air-Britain (Historians) Ltd, 2009. .
Brown, Don Lambert. Miles Aircraft Since 1925. London: Putnam & Company, 1970. .
Brown, Eric. "Miles M.52: The Supersonic Dream." Air Enthusiast Thirteen, August–November 1980. pp. 35–42 .
Brown, Eric. The Miles M.52: Gateway to Supersonic Flight. Stroud, Gloucestershire, UK: The History Press, 2012. .
Brown, Eric. Wings on my Sleeve. London: Weidenfeld & Nicolson, 2006. .
Breaking Sound Barrier. Secret History (Channel 4) documentary, first broadcast 7 July 1997. Heavily re-edited as Faster than Sound. NOVA (PBS) documentary, first broadcast 14 October 1997.
Buttler, Tony. "Miles M.52: Britain's Top Secret Supersonic Research Aircraft". Crécy Publishing Ltd, Manchester, 2016. .
McDonnell, Patrick. "Beaten to the Barrier." Aeroplane Monthly Volume 26, No. 1, Issue 297, January 1998.
Miller, Jay. The X-planes: X-1 to X-45. Midland Publishing, 2001. .
Pisano, Dominick A., R. Robert van der Linden and Frank H. Winter. Chuck Yeager and the Bell X-1: Breaking the Sound Barrier. Washington, DC: Smithsonian National Air and Space Museum (in association with Abrams, New York), 2006. .
Temple, Julian C. Wings Over Woodley – The Story of Miles Aircraft and the Adwest Group. Bourne End, Bucks, UK: Aston Publications, 1987. .
Wood, Derek. Project Cancelled. Indianapolis: The Bobbs-Merrill Company Inc., 1975. .
Yeager, Chuck et al. The Quest for Mach One: A First-Person Account of Breaking the Sound Barrier. New York: Penguin Studio, 1997. .

External links

Faster than Sound – Nova documentary
transcript of the Nova programme
Jets45 Histories
A video of a modern radio controlled model replica of the M.52 flying
Eric "Winkle" Brown talks about the M.52 in 2008
Museum of Berkshire Aviation: "The M.52 Story"
"High Speed Research" (pdf download). The Aeroplane Spotter, 19 October 1946.
"Miles on supersonic flight." Flight, October 1946, p. 355.
Supersonic Approach by H. F. King, M.B.E.Flight 3 April 1947
Ministry of Supply report "Flight Trials of a Rocket-propelled Transonic Research Model: The R.A.E.-Vickers Rocket Model"
"Transonic Research" a 1946 Flight article on the M.52-based Vickers test rocket.