Miles M.52: Difference between revisions

The '''Miles M.52''' was a turbojet-powered [[supersonic aircraft|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 [[List of Air Ministry Specifications|Air Ministry Specification E.24/43]]. The programme was highly ambitious for its time, aiming to produce an aircraft and engine capable of unheard-ofa speedsspeed of at least {{convert|1000|mph}} during level flight, and involved a very high proportion of cutting-edge [[aerodynamics|aerodynamic]] research and innovative design work.

Until 1945 all work on the project was undertaken with a high level of [[Secrecy#Military|secrecy]]. In February 1946, the programme was terminated by the new [[Labour Party (UK)|Labour]] government of [[Clement Attlee]], seemingly due to budgetary reasons, as well as athe disbelief held byof some ministry officials concerningregarding the viabilitypracticality of supersonic aircraft in general. 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 as toof why the project had been terminated and criticism of the decision. The [[AirMinistry Ministryof Supply]] controversially decided to reviveinvestigate 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 the originala manned full-scale aircraft. thatThe hadcontract beenwas previouslyawarded underto development.Vickers Theserather unmannedthan scaleMiles. The models were air-launched from a modified [[de Havilland Mosquito]] [[mother ship]].

DuringA onemodel successfulwith testthe flightM52 configuration of wing and control surfaces achieved [[Mach number|Mach]] 1.38 was achieved by a scale model in normally controllablecontrolled [[transonic]] and [[supersonic]] level flight, a unique achievement at that time and one which validatedprovided "some validation of the aerodynamics of the M.52 upon which the model was based".<ref>{{cite Atjournal|url=https://doi.org/10.1017/S0001924000003602 that|page=154|doi=10.1017/S0001924000003602 point,|title=On the ministryaerodynamics had cancelledof the projectMiles andM.52 (E.24/43) issued– a newhistorical requirement,perspective which|date=2010 would|last1=Brinkworth ultimately|first1=B. resultJ. in|journal=The Aeronautical Journal |volume=114 |issue=1153 }}</ref> Prior to the [[Englishflight Electricthe Lightning]]decision [[interceptorhad aircraft]]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 the Power Jets company 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]], a ground-breaking high-speedthe experimental aircraft which broke the sound barrier.

Prior to the [[World War II|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]].<ref name = "wood 27">Wood 1975, p. 27.</ref> 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 [[G. I. Taylor|Sir Geoffrey Taylor]], and British engine designer [[Stanley Hooker|Sir Stanley Hooker]].<ref name = "wood 27 28">Wood 1975, pp. 27–28.</ref> 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 engine|rocket-propelled]] [[Messerschmitt Me 163]] orand the [[jet propulsion|jet-propelled]] [[Messerschmitt Me 262|Me 262]], both with swept wings, did widercaused attitudes on its merits begin to change. PriorBy to this point,then the British [[Air Ministry]] had already launched a research programme of its own.<ref name = "wood 27 29">Wood 1975, pp. 27–29.</ref>

In Autumn 1943, the Air Ministry issued [[List of Air Ministry Specifications|Air Ministry Specification E.24/43]] calling for a [[jet engine|jet]]-powered research aircraft capable of reaching [[supersonic]] speeds, far faster than any aircraft had ever flownflying at that point .<ref name = "wood 28 29">Wood 1975, pp. 28–29.</ref> It called for an "aeroplane capable of flying over {{convert|1000|mph}} in level flight, (over twice the existing speed record at) that time, along withand the ability to climb to {{convert|36000|ft}} in 1.5&nbsp;minutes.<ref name = "wood 28 29">Wood 1970, pp 28-29</ref> 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".<ref name = "wood 29"/> In fact, the specification had only been intended to produce a British aircraft that could match the supposed performance of an apparently existing German aircraft: the 1,000&nbsp;''mph'' (supersonic) requirement had resulted from the mistranslation of an intercepted communication which had reported that the maximum speed to have been 1,000&nbsp;''km/h'' ([[speed of sound|subsonic]]). This report is believed to have been referring to either the Messerschmitt Me 163A or the Me 262.<ref name="Discussion">[http://www.space.co.uk/DataBank/VideoGallery/VideoPlayer/tabid/384/VideoId/33/Test-Pilot-Discussion.aspx "UK Space Conference 2008: Test Pilot Discussion."] {{webarchive|url=https://web.archive.org/web/20110724145755/http://www.space.co.uk/DataBank/VideoGallery/VideoPlayer/tabid/384/VideoId/33/Test-Pilot-Discussion.aspx |date=24 July 2011 }} ''http://www.space.co.uk''. Retrieved: 12 October 2009.</ref>

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 [[Miles Aircraft#Aircraft|company's products]] were relatively low-technology aircraft, and did not include any [[jet propulsion|jet-propelled]] aircraft,<ref name="Brown 1970">Brown 1970.</ref> 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.<ref name="Brown 1970"/> Miles was invited to undertake a top-secret project to meet the requirements of Specification E.24/43; thus began Miles' involvement in high-speed aviation.<ref name = "wood 29">Wood 1975, p. 29.</ref> 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]];<ref name="Brown 1970"/> Wood states that the [[Minister of Aircraft Production]] [[Stafford Cripps|Sir Stafford Cripps]] had been impressed by Miles' designs and development team and thus favoured it to meet the specification.<ref name = "wood 29"/>

[[Frederick George Miles|FredF. G. Miles]] of Miles Aircraft was summoned to the Ministry of Aircraft Production to meet with researcher [[Ben Lockspeiser]] for, the latterdirector toof scientific research, who outlineoutlined the difficulties and challenges involved in developing such an aircraft.<ref name = "wood 29"/> The project required the highest level of secrecy throughout, Miles being responsible for the development and manufacturing of the airframe while [[Frank Whittle]]'s [[Power Jets]] company developed and produced a suitable engine to equip the aircraft. For this project, Miles would cooperate with and receive assistance from the [[Royal Aircraft Establishment]] (RAE) in [[Farnborough Airport|Farnborough]] and the [[National Physical Laboratory (United Kingdom)|National Physical Laboratory]].<ref name = "wood 29"/> On 8 October 1943, Miles received the formal go-ahead to proceed from [[Air Marshal]] [[Ralph Sorley]], and immediately set about establishing appropriate secure facilities for the project.<ref name = "wood 29"/>

Faced with limited amounts of existing relevant information from available sources upon which to base the aircraft's design, Miles turned to the field of [[ballistics]] instead.<ref name = "wood 29"/> He reasoned since bullets could reach supersonic speeds, aerodynamic properties that would enable an aircraft to be capable of becoming supersonic would likely to be present amongst such shapes. In particular, as a result of studying this design data, the aircraft would have both a conical nose and very thin wings complete with sharp [[leading edge]]s.<ref name = "wood 29"/> This contrasted with many early jet aircraft, which had roundrounded noses, thick wings and hinged [[elevator]]s, resulting in these aircraft having local regions of supersonic flow ([[critical Mach number]]s) at belowrelatively thelow speedflight ofMach soundnumbers; thus they were less suitable for research into high subsonic speeds (in dives) than the earlier [[Supermarine Spitfire]] with its thinner wings. In 1943, RAE tests conducted using Spitfires had proved that drag was the main factor that would need to be addressed by high-speed aircraft.<ref>Brown 1980, p. 36.</ref>

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 [[tailplane]]s (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 [[Center of pressure (fluid mechanics)|centre of pressure]], which together could override the control forces that could be applied mechanically by the pilot, hindering recovery from the dive.<ref name="Brown 1970"/><ref>[[Roland Beamont|Beamont, Roland]]. ''Testing Early Jets''. London: Airlife, 1990. {{ISBN|1-85310-158-3}}.</ref> 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 consideredrequired tofor be a minimum condition ofnon-delta enablingwinged aircraft to breakpass through the transonic barrierregion safelyto supersonic speeds without a loss of pilot control. The M.52 was the first instance of this solution, which has since gone on to be universally used for high-speed aircraft.{{Citation needed|date=January 2021}}

An initial version of the aircraft was to be test-flown using [[Frank Whittle]]'s latest engine, the [[Power Jets]] W.2/700.<ref name = "wood 30"/> This engine, which was estimated to be capable of providing 2,000&nbsp;lb of thrust, calculated to be only capable of providing subsonic performance in level flight but when flown in a shallow dive capable of transonic flight. Wood described the engine as being "remarkable as it incorporated ideas far ahead of its time".<ref name = "wood 30"/> In order to getFor the M.52 to achieve supersonic speeds, the installation ofa projectedhigher furtherthrust developmentversion of the W.2/700 engine would be necessary.<ref name = "wood 30"/>

ThisThe furtherextra advancedthrust modelrequired of the engine, intended to powerfor a fully supersonic version of the aircraft, waswould partiallycome achievedfrom bymore theairflow incorporationfrom of aan ''reheat jetpipeaugmentor'' –fan alsodrawing knownair asaround anthe [[Afterburner (engine)|afterburner]].<ref namethrough =a "woodbypass 30"/> Extra fuel was to be burned in the tailpipe to avoid overheating the turbine blades,duct makingand usecombustion of unused oxygen presentfuel in the exhaust. To supply morebypass air tobehind the afterburner than could move through the fairly small engine, an ''augmentor'' fan powered by the engine was to be fitted behind the engine to draw air around the engine via ducts.<ref>[http://www.flightglobal.com/pdfarchive/view/1946/1946%20-%201965.html "Miles on Supersonic Flight."] ''Flight International'', 3 October 1946. p. 355.</ref><ref name = "wood 30"/> These changes were estimated to provide an additional 1,620&nbsp;lb of thrust at 36,000&nbsp;ft and 500&nbsp;mph. Much greater thrust gains were believed to be available at speeds in excess of 500&nbsp;mph.<ref name = "wood 30"/>

The fuselage of the M.52 was cylindrical and, like the rest of the aircraft, was constructed of high tensile [[steel]] with light- alloy covering.<ref name = "wood 30">Wood 1975, p. 30.</ref> The fuselage had thea minimum5 cross-sectionfoot allowablediameter aroundwith thean centrifugal engine withannular fuel tankstank inaround athe [[saddle]]-likeengine.<ref arrangementname placed= over"wood the upper area around it.30"/> The engine was positioned with its [[centre of gravity]] coincidentclose withto that of the aircraftairframe and the wings were attached to the main structure just aft of the engine.<ref name = "wood 30"/> The use of a [[Inlet cone|shock cone]] in the nose was another key design choice; the inletconical coneshockwave slowedfrom incomingthe airpointed tonose theproduced subsonica speedslower determinedloss byin theram engine,pressure butfor withthe lower lossesengine than a subsonicsupersonic aircraft pitot intake. A retractable [[Tricycle landing gear|tricycle undercarriage]] was used. The nose wheel was positioned close tobetween the pilot's feet and the main wheels were fittedaccommodated ontowithin the main fuselage, folding out under the wings when deployed.<ref name = "wood 30"/>

The M.52 had very thin wings of [[Biconvex optimization|biconvex]] section, which had been first proposed by [[Jakob Ackeret]], assince they gave a low level of [[wave drag|drag]]. These wings were so thin that they were known to test pilots as '[[Gillette (brand)|Gillette]]' wings, named after the brand of [[razor]].<ref name= "Discussion"/> The wing tips were "clipped" to keep them clear of the [[Cone (geometry)|conical]] [[shock wave]] thatwhich was generated by the nose of the aircraft. Both wide-[[Chord (aeronautics)|chord]] [[aileron]]s and split-[[Flap (aeronautics)|flap]]s were fitted to the wings.<ref name = "wood 30"/> As a high-speed wing of this shape and size had not been tested before, Miles produced a full-scale wooden model of the wing for aerodynamic testing purposes; other representative portions of the aircraft, such as the tailplane, would be similarly produced and underwent low-speed flight testing.<ref name = "wood 29 30">Wood 1975, pp. 29–30.</ref>

The M.52's pilot, who for the first flight would have been the test pilot [[Eric Brown (pilot)|Eric Brown]], would have flown the aircraft from a small [[cabin pressure|pressurised]] ]cockpit which was set inside the shock cone forming the nose of the aircraft.<ref name = "wood 30"/> in which theThe pilot would have had to fly the aircraft in a semi-[[Prone position|prone]] position,{{fact]] with a curved windscreen that was aligned with the contours of the bullet-shaped nose. In the event of an emergency, the [[Escape crew capsule|entire section could be jettisoned]], the separation from the rest of aircraft being initiated by multiple [[cordite]]-based [[explosive bolt]]s.<ref name = "wood 30"/> Air pressure would force the detached capsule away from the fuselage and a parachute would slow its descent, then the pilot would bail out at a lower altitude.<ref name = "wood 30"/> In order to serve its role as a research aircraft, the M.52 was to be equipped with comprehensive flight instrumentation, including automatedwith instrument recordersreadings andphotographed strainautomatically gaugingand throughoutstructural the[[strain structuregauge]] connectedreadings tophotographed on an [[oscilloscope]].<ref name = "wood 31"/>

During 1943 a single [[Miles Falcon|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.<ref name = "wood 29 30"/> Owing to the wing's thinness and sharp leading and trailing edges somewhat resembling a [[Safety razor|razor blade]], the aircraft was nicknamed the "Gillette Falcon". On 11 August 1944, this low-speed demonstrator performed its [[maiden flight]].<ref name = "wood 30"/> These tests found that the wing had favourable [[aileron]] function, but also indicated that landing without [[Flap (aeronautics)|flap]]s would be more difficult than its contemporaries.<ref name = "wood 30"/> Compared with a standard Falcon Six, wing area was reduced by about 12 per cent; it had the effect of increasing the landing speed by over 50 per cent from {{convert|40|to|61|mph|abbr=on}}, higher than any prior aircraft.<ref>[http://museumofberkshireaviation.googlepages.com/high_speed_research.pdf "High Speed Research."]{{Dead link|date=January 2024 |bot=InternetArchiveBot |fix-attempted=yes }} ''The Aeroplane Spotter'', 19 October 1946. Retrieved: 12 October 2009.</ref><ref name = "wood 30"/>

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]].{{Citation neededcn|date=DecemberJune 20162024}}

On 8 October 1947, the first launch of a test model occurred from high altitude; however, the rocket unintentionally exploded shortly following its release.<ref>Brown 2007, p. 276.</ref><ref name = "wood 37"/> Only days later, on 14 October, the [[Bell X-1]] broke the sound barrier. There was a flurry of denunciation of the government's decision to cancel the project, with the ''[[Daily Express]]'' taking up the cause for the restoration of the M.52 programme, to no effect.<ref>[[Peter Masefield|Masefield, Sir Peter]]. ''[[Secret History (TV series)|Secret History]]'': "Breaking the Sound Barrier" Channel 4, 7 July 1997. Re-packaged as ''NOVA'': [https://www.pbs.org/wgbh/nova/transcripts/2412barrier.html "Faster Than Sound."], PBS, 14 October 1997. Retrieved: 26 April 2009.</ref> 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.<ref name= "Brown p. 42"/> By this point, the X-1 and Yeager had already reached M1.45 on 25 March of that year.<ref>Miller 2001, {{page needed|date=December 2016}}.</ref> 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,<ref name= "Brown p. 42"/> being followed up immediately by the issue of [[List of Air Ministry specifications#NavalPost requirement/Aircraft,1949 Navalspecifications. Air Staff requirementsOperational Requirements/targets|Ministry of Supply Experimental Requirement ER.103]].{{Citation needed|date=January 2021}}

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 highly regarded 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.{{Citation needed|date=January 2021}}

* [http://museumofberkshireaviation.googlepages.com/high_speed_research.pdf "High Speed Research" (pdf download). ''The Aeroplane Spotter'', 19 October 1946.]{{Dead link|date=January 2024 |bot=InternetArchiveBot |fix-attempted=yes }}