British Aviation and the Sound Barrier

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British Aviation and the Sound Barrier

The breaking of the sound barrier represented a step change in aviation, aerodynamics and engineering. The methodology employed to break the sound barrier in Britain is a classic study of war-time science with a huge post-war effect made more interesting by the fact there is relatively little research or concern paid to its origins. The story here may not be of the classic popular ideal of British inventors creating incredible inventions from spare parts but is instead a more accurate account of the problems and processes of the British wartime government and its collaboration with science and industry. The sound barrier had been known for some time before World War II as the massive increase in drag experienced as an object’s speed closes to the speed of sound with drag falling dramatically after the object surpasses that speed. The decision to research the sound barrier in Britain was only made by the government during World War II and hence this work will focus on those years and the pivotal post-war years when the sound barrier was actually broken.

It is important to note at this juncture that the sound barrier in British military aviation has had no real academic study bar more popular studies of specific aircraft[1][2]. More sophisticated work has however been conducted in the areas of turbojet development[3][4], the aviation industry in Britain[5], British industry and government during the war[6], the history of aerodynamics[7] and even the scientific personalities in the wartime government[8]. The current literature on these surrounding areas ranges from journalistic accounts of aircraft development to sophisticated philosophical of technological change but little history of science on the sound barrier research itself. When discussing British wartime science and industry Edgerton is the obvious choice for the popular academic opinion. The popular belief of British wartime science of Barnes Wallace and William-Wallace, eccentric inventors on a shoe string budget is representative of the ‘national myth about the niceness and decency of England’[9]. Edgerton argues the true nature of England as a technological and militant nation is masked by this myth perpetuated by the government themselves following the war. Whilst this myth is an interesting example of British self-perception lasting to this day its accuracy may certainly be called into question. Certain tales of British invention may indeed adhere to this myth but as Edgerton points out following that myth or directly opposing it leads to ignoring the failures of technology and science in war or ignoring the strong technological tradition in Britain. This work will then try not to fall into these pitfalls and instead discuss directly the project of supersonic research in Britain around and during World War II.

Other work on parts of supersonic research such as jet engines or aerodynamics have less of a history of science stance and instead have other academic end goals. For example, work on jet engines has considered the technological innovation in varying lights and in different countries. Much of the work has focussed on American and German efforts. Whilst the work of these nations is not insubstantial it is important to note that the British work far exceeded that of the Americans in the early post-war years (in part owing to the technology obtained from the Germans). American work on aerodynamics before and during the war was again inferior to the Germans but owing to their funding and facilities exceeded our own. The lack of focus on the British effort is then perhaps excusable. When looking at a combined picture of a supersonic research programme that encompasses all the work done as a whole it will naturally draw from work on the various aspects such as the aircraft, engines, aerodynamics, government-industry relations etc. The lack of coherent histories of science on aviation research post 1930[10] Britain and especially on the sound barrier as a government wartime project mean this work will encompass many different aspects, taking parts from current surrounding literature as well as original archival research. Hence this work will attempt to strike a balance between the histories of warfare and science of specific projects such as the spitfire or invention of radar and broader government and science studies in the war.

The notion of the sound barrier is fundamentally scientific, however, the impetus and drive to break the barrier has been a profoundly military based affair. Scientific research into problems linked to the sound barrier and aviation such as compressibility existed before the war due to the speed of aeroplane propellers getting closer to and then exceeding the speed of sound with the Aeronautical Research Council producing research into sub-sonic and super-sonic flows in 1918[11]. Compressibility is the phenomenon of flowing air density over a body increasing with the bodies speed and was not a flight issue for lower speed biplanes of the inter-war period but would become extremely important. Obviously here the sound barrier refers to the breaking of the barrier by aircraft for research purposes and not in the instance of propellers, or ballistics for that matter! The concept of the sound barrier did pre-date the more concerted efforts to push aircraft through it which was known to be advantageous from 1910 following the publishing of a paper[12] indicating the decrease in drag following the sound barrier hence showing it could be broken.

Hence the question of why the sound barrier was broken is both interesting and relevant to the argument. There are several possible answers to this question that are relevant in different times, states and bodies of people. It would be false to argue that the drag decrease after the sound barrier was a major deciding factor in Britain. Instead the military instigation of research was in direct reaction to evidence[13] obtained in1943 of Nazi jet aircraft and rockets approaching the sound barrier. This is evidenced by the forming of the Supersonic Committee from the participants in the discussion[14] of the evidence and an initial report[15] on a programme of required work for supersonic research. In fact the desired urgency of the research is adequately surmised by the Controller Research and Development for the Ministry of Aircraft production, ‘I hope that too much time and effort is not being devoted to questioning the accuracy of such reports, rather than accepting them on their face value and going straight to the point of what we are going to do about them and what ought we to be doing on similar lines’14.

The reason for the German’s supersonic research is a classic arms race. The speed of fighters in WWII increased throughout the war to the point where unconfirmed reports of piston engine fighters breaking the sound barrier were recorded from 1943 onwards. This increase in speed represented a form of strategic and tactical arms race. Strategically, the fastest fighters could launch from better supplied airfields closer to their nation and still deter the enemy at a greater distance from the assets that needed protecting. Tactically, the fighters with a higher speed had a greater advantage in a dog fight by maintaining their energy better in the turn and climb (the tactics of aerial warfare shall not be covered in more detail here). These were the primary military reasons for the German’s desire to push the sound barrier so that the increase in plane speed could be maintained. The obvious fear being that the enemy were getting faster and hence that state required a faster plane to combat the threat effectively. For the military then, the sound barrier initially was just that, a barrier that needed to be broken in order to produce the greater speeds necessary for improved combat ability.

The political reasons mix nicely with both the military and scientific reasons for breaking the sound barrier. As mentioned above, one of the the political advantages of breaking the sound barrier is the military deterrent of having that technology. In the same way that a nuclear deterrent acts, the ability to go faster than the speed of sound effectively renders sub-sonic aircraft useless in air-to-air combat. There are two other main political concerns with the sound barrier. These relate to the prestige of the industry surrounding the sound barrier. The political prestige of being a ‘super-sonic’ nation on the world stage is in itself politically important, placing that state amongst a small but rising number of highly technologically competent states. Leading into the cold war and the nuclear arms race there is a nice parallel to be seen with all technologies relating to nuclear armament.  The other political power generated from super-sonic flight is economic. The industries in support of breaking the sound barrier had developed world-leading technology and standards which were capitalised on by the government to sell abroad. The obvious British examples being Rolls-Royce which sold licenses and manufacturing rights for jet engines after the war.

This work is split into multiple sections. The following section on committees analyses the wide-spread use of committees in British war-time research and military activities. This section will serve as an excellent starting point to show how supersonic flight was increasely considered as the next step in aeronautical research and was embodied in the development of the Miles M.52, a plane effectively designed for research by committee. The next sections focus on the two most well-known and collective areas of supersonic research: propulsion and aerodynamics. The section on propulsion will focus on both the interaction of Whittle and the Air Ministry with the development of jet engines as it was Whittle’s designs that spawned the first two attempts (second being successful) jet engines to break the sound barrier in British aviation. References will also be made to the De Havailland 108 Swallow. This was the first British aircraft  to do so, in 1948. This aircraft however was not designed to break the sound barrier and the accidental nature of its foray past the barrier makes it of less interest to this work than the Miles M.52. In interests of chronological sign-posting it is important to note the American Bell X-1 was the first aircraft to ever break the sound barrier on October 14 1947 and continued to do so. The DH 108 was reported to break the barrier on September 16 1948[16].

Committees

 

It is hard to underestimate the British reliance on the committee during World War II. However, if beurocracy really is the only way to unleash the power of a large organisation then committees are surely an area worth consideration. That being said the web of aviation related departments and committees is often hard to keep track of. Starting from the top there are several organisations worthy of note. The Royal Air Force (RAF) as the prime future user of the supersonic work conducted in this period are an obvious inclusion. Related to the RAF is the Air Ministry, Ministry of Supply (MoS) and the Ministry of Aircraft Production (MAP). These organisations are somewhat self explanatory in that their roles were to govern the use of aircraft and develop and procure aircraft for the RAF. Considering the RAF now purchases its own aircraft directly it is easy to expect tension to arise here, as in many overlapping areas of control in this period. Separate to and smaller than these larger organisations were the National Physical Laboratory (NPL), the Department of Scientific and Industrial Research (DSIR) and the Aeronautical Research Council (ARC). These scientific institions proved vital in industrial and military technological advancement. The ARC and DSIR were designed to guide research and report directly to the government as opposed to any individual ministry. The Royal Aircraft Establishment at Farnborough must also be mentioned here due to its enormous role in aeronautical research throughout the early and mid twentieth century. The RAE came under the war ministry during the War. The RAE did not produce its own independent aircraft but conducted its own research into aeronautical matters as well as test and development of existing aircraft.

It is important to note the method during the war of aircraft procurement. The MAP would issue an Operational Requirement (OR) with a task or mission in mind: e.g. night fighter, medium range, one seater. The OR would then lead to a specification which was more specific with exact details. Manufacturers would then produce aircraft to that specification in a competition to win the contract. This system lasted until the 1970s when the massively complex nature of aircraft design and the increasing time for research and development meant the industry took the lead on aircraft sales. Now it is common practise for government to identify a need and for industry to then bid and design their own answer to that need. In effect the research and development shifts from the strict designs of the government to industry to theoretically allow for more innovation.

However, perhaps the most critical committee to mention here is the “Supersonic Committee” born in May 1943 as part of the DSIR. This committee was set up to discuss the findings of a German prisoner who purported to have information on a German high-speed, high-altitude long range bomber. The military advantage of such a project warranted the thorough investigation it received. The advanced nature of the discussed German research into the sound barrier and supersonic flight is most arguably what initially launched the British effort to break the barrier. The reasons for this style of arms race were discussed in the introduction. The supersonic committee operated separately to the MAP, MoS and to the ARC but acted in a similar way to the ARC but with more power. The  supersonic committee had a more active role of investigating and organising the solving of problems of supersonic flight. The committee therefore had much more autonomy than the ARC and more power to recommend research programmes and aircraft to be built as will be seen.

The role of the ARC is neatly summised by then prime minister at its inception in 1909 and creator of the committee: Lord Asquith, ‘”It is no part of the general duty of the Advisory Committee For Aeronautics either to construct or invent. Its function is not to initiate, but to consider what is initiated elsewhere, and is referred to it by the executive officers of the Navy and Army Construction Departments. The problems which are likely to arise … for solutions are numerous, and it will be the work of the Committee to advise on these problems, and to seek their solution by the application of both theoretical and experimental methods of research”. The role of the ARC in reporting directly to government, post 1918 this was to the secretary for air, was to identify and recommend problems to other organisations to solve. The committee then plays the role of the exploratory middle-man between the identifiers of problems and those with the powers to solve them.

The sub-committees of the Supersonic Committee and the ARC are all extremely complex. The ARC in the years 1939-1948 had 3 committees, 10 sub-committees and 6 special committees. Members of these committees ranged from government officials of the MoS or MAP to RAF or Naval Officers as well as scientists and representatives from the NPL and industry. Members of the Council often had places on the various other committees and sub-committees as distinguished officials and scientists with the larger picture of their goal more obvious to them than to the shorter term specialists in their fields. The Supersonic Committee is in itself an excellent example of the committee mindset of the wartime government science programme. Most scientific questions relating to the war in the war period were answered by committee. Committees were often short-lived but served the role of centralising research to a designated body with the idea of concentrating expertise and maximising the efficiency of industry and scientists in the country.

This section will look at specific themes of and events involving the committees participating in supersonic research in Britain. The work of the committees is most relevant from the inception of the Supersonic Committee up to its disbandment in 1946 and hence this is the period in which this section will focus. We will look at what is perhaps the embodiment of the committees work which is the Miles M.52 aircraft. We will look at the impact of the committee on this aircraft and the role of the committee in its commissioning, design, role and eventual destruction. The focus on the development of a supersonic aircraft is the best way to see the role of the committee on aviation and sound barrier research as for the aircraft to be successful all the related areas of study had to be focussed on a single target of breaking the barrier. The theoretical and practical work in the design and production of the aircraft represent the style of the committee and combines all their work in their three years hence the development of the aircraft really is the focal point of the supersonic research.

The initial two meetings of the committee to discuss the new German evidence consisted of only scientific and government personal. This changed as the committee learned of the advanced nature of the German super-sonic research and hence the role of the committee changed. It is arguable the committee initially formed to assess the truth of the claims the German soldier made and to assess how far ahead the Germans were in high-speed aviation. Their findings lead to the committee becoming quite clearly active in dictating and producing high-speed aeronautical research. This step change is evidenced by the addition in the third meeting of a representative from Rolls-Royce and a decrease in members from the Forces. The importance of this committee is evidenced early on by it being chaired by the Director of Scientific Research Ben Lockspeiser. Lockspeiser’s later role as the first president of CERN and his promotion to Director General of DSIR show the administrative and scientific skill that Lockspeiser possessed and arguably learnt during the handling of the numerous committees in DSIR.

From the first meeting scientific work was required of the committee. The first instance of commissioned practical research occurred during the second meeting on the 4th June 1943. The work comprised of creating and testing a supersonic capable airplane model in a sub-sonic wind tunnel in order to start assessing the different flight dynamics at sub-sonic, trans-sonic and super-sonic speeds. This job fell to Mr E Relf of the NPL who was tasked to work with the RAE to produce the model and then use the facilities at the NPL to conduct the testing. The committee here has clearly identified the problem of aircraft handling through the high-speed range and designated the necessary scientific work to a team for completion. This is a useful neat example of how practical scientific knowledge was deemed necessary, farmed out to the relevant members of the committee for completion and to be reported back on. This is the pattern that follows for specifically commissioned research. Problems were identified and designs drawn up and research carried out by varying teams of different back grounds and roles based on the task to be conducted. Other work drew on existing teams and research such as that carried out by the RAE and the ARC with its various committee and sub-committees already specialists in their areas with large bodies of useful work.

The very first instant of supersonic committee specific work was decided to investigate the application of the German athodyds for a British bomber. The use of the athodyd specifically will be discussed in greater detail in the propulsion section. Athodyds were the term used throughout the war to describe what we would now call after-burners whereby there is an addition of fuel and oxygen to the jet exhaust to massively increase thrust. The attitude of the committee here shows the early attitude of the committee being less research based and more for benefitting current designs than it became in the later years. The use of athodyds on current aircraft was found to pose no benefit but their use in supersonic capable aircraft would prove extremely useful. This example serves to show the change of the attitude of the committee in later years upon having a more obvious research capability and agenda to pursue supersonic flight as a means to its own ends. This is made clear from the third meeting in which a report on work conducted by the RAE on athodyds show their capability at higher speeds over a standard jet engine. The RAE had conducted this specific high-speed research in contrast to the aim the Supersonic Committee in initially calculating their practicality in existing designs. This work by the RAE gave the supersonic committee both the practical foundation for high-speed research as it was already underway at the RAE and as a result of that, the ability to act as a more pure research body and less as a body designed for simply military ends.

From the very early meetings it is clear that the committee intended to have Miles construct a high speed research aircraft and promised the job to Miles before the contract became official. This method of designating manufacturers for certain specifications is somewhat novel but not unprecedented if the manufacturer is an expert in a certain field. Both the RAE and NPL produce preliminary designs and forewarned the Miles company of their plan. The desire to use the Miles company was born out of the companies and managers enthusiastic attitude towards research and development. Despite the expertise of the company and the company being closest to the problems faced they were never invited to sit on the committee. In fact the employees of Miles involved in producing the M.52 did not know of the existence of the committee. This is an extremely interesting aspect of the committee. It was common practise for the involved industry to sit on other war time development committees to ensure optimum communication of constraints, progress and problems. In this case however the scientists and officials of the committee, the NPL and the RAE only passed on design changes for the aircraft in smaller scale discussions on practicality with the Miles company. The expertise of the Miles designers was not valued at the meetings. The designers did however meet with the officials of the RAE and NPL regularly as well as other agencies to conduct their own research and use the existing reports from those organisations. The absence of Miles employees from the supersonic committee meetings is still curious as the style of the committee of identifying and discussing problems and distributing the workload could save the Miles company time in constant communicating of their problems to the relevant parties with requests for information or assistance. The problems raised in many of the meetings were of direct consequence to Miles and were often issues raised by the company to the individuals in the meeting and hence their absence simply created another step in the communication change. This is perhaps an instance of the impairment of beurocracy or perhaps the effect of secrecy on scientific research. This is a common time of project science during the war years owing to the abundance of committees and individuals with different authorisations and levels of security clearances. Hence, a possible disadvantage of project science like this means that not all branches of the project are equally represented or kept sufficiently informed. This may have elongated the time scale of the project but given the highly secret and important nature of the work is not a surprise.

A further development in this issue is the nature of the specification issued to Miles. The specification E.24/43 was the shortest specification the ministry ever issued based clearly around a high climb rate and top speed. The specification left Miles with far more room for innovation than other specification designed for purely military purposed had and is much more representative of the type of specification in use today. The design was left open to adjustment by various members of the committee, most notably by Frank Whittle who’s place on the supersonic committee stemmed mostly from his ownership of the Power Jet company. It was decided in the specification given to Miles that the Whittle W.2/700 jet engine would be used hence allowing Whittle a more intimate involvement. A more in depth discussion of the different engine options will appear later.

Whittle’s involvement is even more obvious in his initial memo on the Miles aircraft on the 23rd October. The memo included a rough list of all the requirements of the airplane and appears to be discussed in tandem with the Miles company. This is at odds with the later lack of cooperation in between the committee and Miles. Whittle elaborates on the initial specification to provide more detail on the final design constraints that Miles would need to stick to. The constraints calculated are of a scientific nature as opposed to an arbitrary committee imposed restraint hence still allowing Miles autonomy over the project.

Miles was left a mere 9 months to construct the aircraft completely. Given that the latest military fast jets such as the Eurofighter Typhoon and F-35 took around 30-40 years to become ready for use the 9 months to produce such a revolutionary machine was obviously too short. Combining this time constraint with the lack of communication and sharing of information from the crucial supersonic committee we can see how the Miles company may not have been offered the best chance to succeed. The time limit was not aided by the reasonably low priority and beurocracy that the company and committee would have to face. The signatory of the contract and the effective head of the project, the Controller of Research and Development in the MoS stated any individual priorities would have to be related to the war effort and weighed up against existing obligations. The priorities here could range from wind tunnel use, hangar space and airfield acquisition, production using other companies etc. This line is not unexpected given the nature of the existing war research having much more immediate impacts: the constant upgrading of the spitfire.

A letter on the 8th November 1943 from Miles related the intitial plan of the aircraft with other options considered. Several questions and initial problems were raised regarding the programme. The issues raised show how the project was to work in reliance on the committee and the government. The company required staff to be hired by the MAP, aircraft to be loaned for initial research and a programme with research priorities to be developed by the committee. This heavy reliance is interesting owing to the looseness of the specification of the aircraft and shows how close industry, science and government were becoming due to the war. The loan of aircraft, strict timeline and rent of airfield space and wind tunnels are all examples of aids that the state gave to private industry for research purposes. In a way it could be described as a research contract given to the Miles company to perform scientific research and development in the area of aircraft manufacture which the state could no do directly. Further proof of these interactions is forthcoming in an internal Miles memo of 8th November. The memo stated that there would be a visit to the RAE to obtain any information relevant to wings, structure, electrics etc necessary for the new aircraft. As well as this there was a planned visit to the NPL to investigate the wind tunnels and discuss necessary model sizes for effective small scale research, the models would then be produced by Miles and tested by the RAE and NPL. The RAE would also be asked to loan a Miles Falcon for further flight tests. These visits and examples of working together and sharing research are critical examples of the interplay of industry and government and the effect that the war had on research in aviation. The time critical and patriotic nature of wartime research and development lead to the close cooperation to ensure the job was completed.

Further evidence of the committees involvement in the design of the final plane come in the form of a memo on the 11th November. The memo poses the question of what engine would be best for the project and whether a larger or smaller intake would result in the greatest thrust to drag ratio. It is important that this work is to be taken by the RAE and not by Miles. The reasons for this are likely the expertise and relative knowledge of more secret jet designs at the RAE and indicate the levels of beurocracy the committee ran through to optimise the aircraft. An alrernate interpretation is that of simply tasking those most competent and ensuring efficiency. Allowing Miles to continue on their current designs and tasking the more research orientated RAE to optimise the engine selection is a classic project science style move. The allocating of jobs and resources to multiple separate parties is similar to the larger scale big science typically seen at CERN on the Manhattan project. The Manhattan project obviously had a single end goal as did the committee. The committee is tasked to investigate problems around the sound barrier and decided one method to be building a full scale aircraft for research to ensure accuracy and reduce workload on smaller scales and maximise research potential. The production and research necessary to create this and investigate other areas of research on the sound barrier are separate but related projects in the same way that heavy water production and ignition mechanisms were separate but related parts of the manhattan project. Indeed further evidence seems to indicate the Miles company more as only the builder of the airplane and in the role of requesting necessary research. This model shows the committee more in the role of the ARC of passing the problems onto the relevant parties for solving and considering what problems required priority.

Evidence of this communication of research needs is easily found in the early stages of design where requests for information from Miles were sent to the MAP, RAE, NPL and the supersonic committee for consideration. Miles initial requests covered stressing factors (g-limits), cabin pressure, wing stiffness and more which all had to be researched and determined by the NPL and RAE. Further work by the RAE lead to the conclusion the current design by Miles would not reach the required air speed and hence they redesigned and consulted Miles. At this stage the RAE and NPL are taking a much more active role in the design of the aircraft as opposed to reviewing current designs or relaying the physical constraints necessary for the speed to be achieved. Perhaps the most obvious piece of evidence for the role of the committees in designing the aircraft was in the meeting to discuss the final specification of the aircraft. It was decided that no deviation be made from the final specification by Miles without the prior consent of the Director of Technical Development (DTD). Following small wind tunnel tests at the RAE using models produced at the RAE from designs by Miles the RAE proposed their own more intricate design changes for chord width, centre of gravity etc. This is important as Miles had also conducted wind tunnel tests albeit at a lower speed but were in less of a position to change the design. The use of the high speed tunnel is essential for the design seeing as Miles did not have the facilities. All modifications were only recommended after discussion with Miles but we can see how the spread of research even within the production of the aircraft is representative of the project nature of the supersonic committee.

The committee continued in this way with the members producing design changes and assisting the company as they could with its low priority. The next important stage of the committee involvement revolves around the cancellation of the M.52. This process arguably started in the 20th meeting of the supersonic committee on the 9th Jan 1945. The minutes of this meeting give the first official mention of a replacement with a new power source. This corresponds with a memo from Prime Minister Winston Churchill signalling a wind down in research and development budgets, especially for aircraft in long term projects coinciding with the ending of the war. Subsequent meetings showed a strong desire for a rocket propelled replacement and to fit a rocket to the M.52 as a test bed for its replacement. This was followed by discoveries of German research at Focke-Wulf showing the benefit of swept wings and massive advantages of rocket power in stability in and attaining supersonic flight. The requirement for service aircraft to be supersonic was believed to be 5 years and hence several meetings of indecision followed whereby the military advantage of jet engines with better endurance were weighed against the more immediate research advantage of rockets propulsion. In the 25th meeting of the committee it was noted that with the new reports from Germany it was possible to design a better supersonic aircraft than the Miles. The following meetings hence focussed on the use of the Miles aircraft as a test bed for a possible future aircraft and on the replacement. Naturally this research into the rocket propulsion units and into swept wings lowered the priority of the Miles aircraft even further. Arguably the final blow to the Miles project came on the 26th Feb 1946. This meeting discussed the spiralling cost of the Miles project which by this point was far from the best design possible. The findings of the committee in favour of smaller radio controlled rocket propelled aircraft for research were passed to the MAP who made the ultimate decision to cancel the contract.

The nature of the committee work conducted on the Miles M.52 is in stark comparison to the work of a similar committee, the Brabazon Committee. The Brabazon committee was formed in 1942 to identify and resolve the air transport, cargo and mail needs of the commonwealth and British empire after the war. In order to solve the countries massive bias towards military aircraft five new aircraft were proposed for civilian purposes to solve these needs. The fourth of these designs was a jet propelled mail plane for the north atlantic. This entire contract was given to the De Havailland company to complete as they saw fit. The committee approved the initial plans in 1944 and in 1945 following the discovery of the German evidence for the advantages of the swept wing the prototypes started to be designed. The DH 108 was only designed as a test plane for the eventual commercial airliner. The 108 was designed to test high speed and low speed flight using a tailless swept wing aircraft. The 108 was not designed or indeed supposed to break the sound barrier but did become the first British aircraft documented to do so in 1948.

The story of the DH 108 then reads very differently to the M.52. Whilst the companies involved both used the RAE for tests and were commissioned by committees it is fair to say the comparisons end there. The 108 used an in house engine desing, the Goblin to propel their aircraft. The 108 was also a stepping stone on the way to an end design for an entirely different purpose hence the pressure on the 108 to break the sound barrier was not an issue as this was not even its research purpose or the purpose of its end design. The company also had effectively free reign to control their own research and development for their final design. This resulted in much more freedom of design and less constant interference as was the case with the Miles. It is important to mention the 108 here not just because it was the first British aircraft to actually break the sound barrier but also to act as a counterpoint to the M.52. Whilst Miles was reliant on the committee for designs, engines and the essentials of aircraft design, DH was completely under its own steam with the 108 with assistance only when required from the RAE. This is perhaps an interesting note on the use of committees in science in that the over management and over control of a project whilst keeping the important information from the necessary parties stifles scientific innovation. Perhaps it is also important to note how accidental the breaking of the sound barrier was in the initial supersonic flight by pilot John Derry who effectively stumbled upon positive supersonic flight during a dive gone wrong.

Perhaps a reasonable conclusion on the wartime project science nature of supersonic research is to state that

 

 

Propulsion

 

There is already a large body of work on the invention and incorporation of jet engines in the aviation industry particularly focussing on their geographical spread (jet race) and applications of technological and innovation models to the usurping of the piston engine by the jet engine (turbojet revolution). Hence focus on the jet engines here will not be on their earliest uses and designs or models of technological change but will focus on their application to British aeronautical research on the sound barrier and the effect of wartime thinking, funding and planning on British jet development.

It is important to note that jet engines were only one method of propulsion considered for use in supersonic research projects. There are examples of fired projectiles, gravity propelled dropped models and other novel forms of propulsion. However of most relevance to this work is the use of rockets, consideration of athodyds as well as the jet engine. Considering the general lack of use of athodyds in Britain their mention will be small compared to the work on jet engines and rockets which were the subject of much more continued research and use.

The relevant individuals to the story of high-speed propulsion on an international scale are generally agreed to be the German Dr Hans Von Ohain, the Frenchman Maxime Guillaume and in Britain, Frank Whittle. Obviously this section will focus on the British efforts, particularly of Frank Whittle who in Britain at least is commonly viewed as the inventor of the jet engine. It is interesting to note however that the first full scale functioning jet engines were produced in both Germany and Britain in 1937. The importance of Guillaume is in his filing of the very first turbojet engine patent in 1920 although there is no evidence to suggest either Whittle or Ohain were aware of this filing.

As well as the individuals involved in the jet engines it is also important to discuss the relevant members of industry and the way in which the government generally handled the jet engine before and during the war. This is not the place to rewrite Whittle’s biography as it is mostly irrelevant and has been produced many times (**). It is however very useful to discuss Whittle’s dealings with the air ministry as well as the way the Air Ministry handled the development of the jet engine as it was Whittle’s initial design that the W.2/700 of the Miles M.52 and the De Havailland Goblin of the DH.108 both came from. I will therefore start with Whittle’s initial interactions with the Air Ministry over his jet engine. There is a natural split in the story of Whittle and the government displayed by the levels of commitment of the government to Whittle’s work with the turning point around 1936. In 1929 Whittle presented his ideas to the ministry to have them rejected due to over-optimistic calculation mistakes, he sent the amended plans the same year to have them rejected on grounds of the materials involved being subject to too high stresses and temperatures. The ministry then shelved the idea and it was up to Whittle and a patent officer to file the provisional specification patent. The ministry was informed but decided not to implement a security clearance on the patent and hence Whittle’s work was published internationally in both the New York Times and German magazines in 1929. The RAF continued to send Whittle for further education until 1936 and both the RAF and Air Ministry had faith in his abilities as an engineer to  innovate in the field of aeronautical research. The jet engine however was not believed to be viable even after it was proved mathematically possible due to the materials and funding required which the private sector would not offer due to lack of civilian uses. This initial dealing of the jet engine by the ministry is typical of the pre-war British attitude towards armament that it was unnecessary and the peace could be maintained in Europe. The funding and support required for Whittle’s work were not forthcoming as the jet engine at this stage really had only military application and that military application was not deemed necessary at the time.

The attitude of the Air Ministry did change somewhat in 1936 following financial backing from banks and the support of aviation experts and agents which lead to the formation of Whittle’s Power Jet company with the Air Ministry requesting reports on Whittle’s centrifugal flow jet engine following the private financial backing. At this stage Whittle was still employed by the RAF and hence was only allowed to spend a mere 6 hours a week with his company under orders by the Air Ministry, obviously this limit was blatantly disregarded. It was at this time that Whittle’s engine was proving possible the ministry employed Metropolitan-Vickers (Metrovick) to produce and test axial-flow jet engines owing to their experience in axial-flow steam turbines. The Metrovick engines were ready much later than the Whittle engines at 1941 but did outperform the Whittle units at this time giving the ministry the faith to pursue the jet engine as a sole propulsion unit for aviation. Following a successful test of Whittles engine in 1937 and a lack of funds promised by the Power Jets shareholders the Air Ministry gave Whittle £10,000 on the back of a letter from the, even then, highly influential Tizzard, head of the ARC. Whittle thus redesigned his engine, the Whittle Unit (WU) and was moved to an abandoned factory on the same site as his original work but further away to prevent disruption at British Thompson-Houston (BTH). It was here that Whittle was able to produce a much longer endurance and thrust from the engine although the thrust was noted to be  difficult to obtain owing to the measuring apparatus being a spring load on the back of a truck behind the jet!

Despite the budget location and testing apparatus Power Jets was still in financial difficulties still owing to the lack of the promised support of their backers. Whittle did however continue with his work doggedly despite the lack of funds. There was a cycle existing in these earlier years of power jets where owing to the constant innovation of the jet engine it needed to be rebuilt almost entirely every year or so to continue to improve at the projected rate. This in itself required substantial funds which the air ministry would only offer on return of those performance gains. Hence the Whittle’s desire to work so hard on the project to ensure each rebuild eaked out the most performance for the price possible. By the end of the 1938 however the air ministry was convinced of the jet engine as a viable single unit propulsion system as registered by its willingness to fund the engines and the company more substantially. 1939 saw a review of Whittle’s special position as an RAF Squadron Leader working full time in effectively a private company when Squadron Leaders were massively in demand, with the DSR unsure of how essential Whittle was to the company and the research. Doubts regarding Whittle’s necessity to the research were alleviated in an engine test run where the W.U showed a huge increase in thrust and RPM as well as allowing Whittle to state to the Director of the DSR, Dr Pye, that he would leave the RAF if necessary to continue his research. Dr Pye inspired by the results and Whittle’s belief in the project encouraged the air ministry to fund further research by purchasing this third incarnation of the W.U. The W.U was bought and to be kept at Power Jets for further research and with Whittle under instruction to build a flight capable engine for a plane designed by the Gloucester aircraft company. Whittle was tasked to stay at Power Jets and received orders from the ministry for the first flight capable jet engine the W.1 and for a larger more powerful W.2 for the next generation of jet aircraft.

This early history of Whittle’s jet engine is extremely important in understanding the relationship between science, industry and government. Whittle in the early history of Power Jets represented the science and research as well as building the jets as a company contracting BTH to supply parts and provide space for their activities. The government initially provided no funding or help but later on the notice of private funding for the project expressed interest and had Whittle report designs to them, the NPL and RAE. The fact that Whittle was an employee of the RAF is of importance in two critical ways. Whittle was required to file his patents in association with the Air Ministry which meant that under the laws of the time, the Air Ministry controlled the patents. Secondly, Whittle was constantly subject to review of his position, although if anything this seems to have incentivised his work to prove the importance of him staying on at Power Jets.

The importance of the Air Ministry owning the patent lies in the ability to distribute the development and research and development of new jet engines. Effectively allowing the ministry to go over Whittle and Power Jets head to coordinate the development of jet engines themselves. In terms of the dissemination of information and building expertise of turbojet technology in industry and development this move is extremely important. This became increasingly important owing to Whittle’s later dissatisfaction with the standard of work of BTH where the necessary precision tools were not possessed. Whittle moved manufacture to Rover following the initial lack of approval and subsequent assisting of the Air Ministry. The Air Ministry also disseminated the patent  to Rolls-Royce for manufacture. All the manufacturing of the engines by order of the ministry had to be run through power jets which although now played no part in engine production was still funded as a research and development facility. These complications to the story are again in the spirit of project and war-time science where private ownership of patents and manufacturing rights is not the most price or time efficient way for the government to procure new developments. The distribution of work from power jets allowed the company to focus on research and developing engines in collaboration with other companies that had the resources, labour and tools to improve the design. This breakdown of the secrecy of the project amongst industry was essential to the development of the new technologies involved such as Whittle commissioning companies specifically to make the new and necessary Nickel-Chromium alloys for the turbine blades, the same alloy blend used today. The role of the Air Ministry then in taking control of jet engine design was vital to the success of the programme both in terms of funding and in their decision to create the programme into a joint industrial project.

**** more on other engine considerations from meetings etc and maybe dh 108

Aerodynamics

 

The study of sound barrier aerodynamics was introduced reasonably early in the story of the sound barrier in 1935. The exponential increase and decrease in drag preceding and following the sound barrier was observed here and was arguably the start of the desire to break the sound barrier to increase efficiency and speed past the transonic region. Despite this early advance in the science of the sound barrier the aerodynamics of breaking the barrier as previously discussed was only scientifically solved five years after the actual first breaking of the barrier. Problems involving fluid flow and supersonic aerodynamics are yet to be solved and engineering approximations are the still the main method of ensuring supersonic flight. This represents a technological understanding of the sound barrier distinct from pure science where the knowledge of the process is in the application of knowledge to the problem and not in the solving of the theory in each case.

Work on the history of aerodynamics by John Anderson has taken a definitively American slant on the area but makes valuable insights into the area. Practical studies of aerodynamics in the early stages of supersonic research were often the limiting factor in the problem of breaking the barrier. In Britain in particular the lack of sufficiently sized variable speed supersonic capable wind tunnels was a major disadvantage compared to Germany and America. This often lead to the testing of individual subsections of the plane in scaled model form being subject to testing as opposed to whole  model tests. This disadvantage whilst not showing in the overall picture represents the struggle of early aerodynamics and the lack of scientific knowledge of what actually happens at the sound barrier.

This section will take a similar stance to the previous sections. The interplay of science and technology will be interesting in examining the larger ideas of the sound barrier as a target of British war time project science. The methodology of aerodynamic research is at the forefront of the sound barrier research and is ultimately the real science that was desired to be researched through the supersonic project. Whilst the propulsion units and methods of production and manufacture were important in going supersonic the key area of research and most necessary part of the formula is the aerodynamic research.

Previous problems of near super-sonic were identified as traits of this flight regime and ranged from massive instability to out of control dive or climb or even flipping at whim. These problems were largely noticed by pilots flying modified spitfires in dives to probe the sound barrier. These initial tests both showed the key problems to be overcome in aerodynamic stability and control surface technology but also developed a factor called the critical mach number. The critical mach number was the mach number the aircraft could be safely flown up to without exhibiting the dangerous symptoms previously mentioned. The quest to break the sound barrier then was a quest to increase this critical mach number by improving the aerodynamics and control surfaces of the planes used.

Aerodynamic theory and testing has existed in various forms arguably from Archimedes around 290BC and have assisted in developing steam turbines and engines as well as in developing the very first manned aircraft. Aerodynamics subsequently came into its own in the 20th century becoming more and more applicable to the ever increasing aviation industry.

The first notion of the sound barrier had early beginnings in shock wave theory in the 19th Century first noted by W.J.M Rankine following the work of Laplace in identifying the speed of sound. Rankine’s work identified the equations for shock waves still in use today and the existence of this work already ready to be applied is perhaps a key reason for the fairly rapid success in the breaking of the sound barrier in the mid 20th Century. It was however Ernst Mach who devised the first experimental proof of the sound barrier by recording using his own invention, the shadowgraph, to show the supersonic shockwave produced by a bullet being fired. It was only following the creation of the ARC in Britain that the crux of supersonic flight was defined as overcoming compressibility problems. Until this time all aircraft flew at speeds slow enough to define the air flow over the body as uncompressible. It was known however, that the propellers of those airplanes often exceeded the speed of sound especially at their tips and hence research was required to optimise their performance. The ARC hence became the first organisation to study the effect of compressibility in aviation. They were shortly followed by the American National Advisory Committee for Aviation, NACA.

The first wind tunnel tests on compressibility started in Britain in 1922 at the RAE where the propellers were measured in great detail in how much lift they produced in relation to the velocity of both the rotational speed and airflow over the propeller. It was here that the a certain mach number was scientifically defined as the point at which the lift generated decreased massively at a certain speed relative to the present speed of sound. The lift was known to increase up to this point and hence the propeller would produce more thrust and hence increasing this pivotal mach number of the propeller would increase its performance. It was then in 1928 that the Cambridge fluid flow Professor Geoffrey Taylor made a distinctly novel advance in the field. Taylor noticed a comparison between fluid flow and electrical current flow. Taylor used this analogy to produce an experiment that resulted in the calculation of the critical mach number for a circular cylinder. This work whilst being both novel and accurate was not further used. Yet it is an excellent example of the innovative approach of British science and industry of the 20th Century that is so often noted as Britishness in certain literature.

British aerodynamic research tends to be overshadowed by the efforts of the Americans and the Germans. This is noted in letters and memos circulating the ARC in 1943 stating that little is known is still known in Britain about compressibility effects especially in the critical transonic region of mach 0.8-1.2. This lack of essential knowledge comes down to poor wind tunnel equipment. Whilst both the Germans and Americans had larger variable speed supersonic wind tunnels by this time the British had small fixed speed supersonic wind tunnels. This disadvantage had major effects on both the aerodynamics of the aircraft design but also on the design of the jet engines. Each part of the jet engine had to be individually tested in the tunnel to ensure its integrity and performance instead of whole sections as the wind tunnel was simply too small. The issue with the design of aircraft is that differences had to be calculated between two very large quantities in  separate aircraft design to optimise the performance. Hence the scale of the model needed to be larger to increase accuracy of the necessary quanitities but obviously this could not be achieved. This is arguably what often lead the Supersonic Committee, the RAE and the ARC to look at other means of measuring the aerodynamic performance of aircraft and components. Novel methods including projectiles fired from artillery units or simply dropped shapes from aircraft both fitted with radio transmitters to transmit the necessary data. It was however the initial decision of the supersonic committee that the compressibility problems would be dealt with most efficiently by a piloted aircraft, hence the M.52. This opinion as noted previously changed to the preference for rocket propelled unmanned aircraft built up with radio control until a manned flight was deemed safe. The impact of poor wind tunnel facilities is hence a key part of the supersonic story. It impacted every aspect of the research and was an issue not fixes until after the war and the Americans had already broken the barrier. It was then a substantial wind-fall for the British to obtain the supersonic research reports from the Germans at the end of the war to make up for the lack of their own information. The lack of wind tunnels is most likely a consequence of their cost to both produce and to run. Supersonic wind tunnels would almost certainly have fallen into the category of long term research which took a back seat during and immediately after the war where subsonic wind tunnels were adequate for testing and improving the current military air fleet which was of more obvious and immediate national importance.

**** more here on rest of supersonic committee aerodynamic research and relation to miles / maybe dh 108

Conclusions

The investigating of and breaking of the sound barrier in British aviation is evidently a complex web of different stories and links between industry, war, government and science. However some general observations have made themselves evident from this study.

Whittle’s early struggle to find traction with the Air Ministry to fund and support his jet engine in comparison with the later attitude of the ministry coinciding with the war show the effect that war has on technological development. Before the war it was obvious to even Whittle that his jet engine was far before its time and only had real applications in war but not on the biplanes still in use. It took the threat of war and fear of other nations having better technology to create the arms race that lead to the development of the jet engine. Whilst the war did provide the grounds for the development of the engine and the need to investigate the sound barrier it is arguable they were not the most favourable conditions for scientific research. Large bodies of men were conscripted into war as opposed to science and research, even Whittle struggled to keep his job at Power Jets. As well as this the nature of the bureaucracy of funding research meant that all research had to be linked to the  war effort and hence longer term projects such as the breaking of the sound barrier required influential backers such as Tizzard and Dr Pye. It is also arguable how the bureaucratic project structure of the various war ministrys and scientific organisations aided the development of supersonic research. Despite the abundance of committees and manpower in the management level it was after the war that the necessary wind tunnels were designed. The Miles M.52 is a strong case for death by committee where the committee’s constant redesign and interference with the project without the involvement of Miles at the supersonic committee’s meetings ultimately lead to the dissatisfaction with the design that lead to its demise. The spiralling costs were one part of the unhappiness with the project that were the result of the redesigns and lack of commitment to propulsion units. By the time they discovered the Germans knew of a better complete design this rung the death knoll as every development in supersonic research possible was adjusted on the M.52 and the new German designs required a completely new aircraft. Obviously one cannot say for certain if the M.52 would have gone supersonic but the donation of all the data and reports on the aircraft to the Americans a year before they went supersonic in a shockingly similar looking aircraft may provide an indication.

Observations about the efficacy of the project aside I believe it is important to classify the target of supersonic research and breaking the sound barrier as project science. This notion is somewhat difficult to define but perhaps by emphasising points made earlier it will become clear. The way the committees functioned in the war was to identify problems and distribute them for solving by the revelant parties. This often resulted in contracted work to companies or sub-committees on important issues. The interplay between these companies, scientists, government organisations etc all comes together to form the end goal of breaking the sound barrier. Individual jobs within this target were obviously the propulsion unit, the aerodynamics, the materials necessary, the manufacturing etc. The supersonic committee tasked groups to deal with each of these problems and coordinated the effort from above with communication running effectively between all parties. The only area this communication was not present in was in the lack of a Miles representative at the supersonic committee meetings. As previously mentioned this the comparison to the Manhattan Project or CERN as typical examples of big or large scale project science are plentiful. For example the end goal of CERN being to probe the subatomic structure of matter requires the individual experiments to be designed and constructed as well the construction of the Large Hadron Collider itself in collaboration with all the scientists necessary to ensure the efficacy of the machine. This is entirely comparable to end goal of conducting supersonic research by building a supersonic plane with all the necessary design work, experiments and individual projects to be completed en route to the end construction of the plane and end goal of its use in research.

Bibliography

 

Brian Rivas. A Very British Sound Barrier: The DH108 – A Story of Courage, Triumph and Tragedy. (Walton-On-Thames: Red Kite, 2012)

Charles Percy Snow. Science and Government. (New York: The New American Library, 1962)

David Edgerton. Britain’s War Machine. (London: Penguin, 2011)

David Edgerton. England and the Aeroplane: An Essay on a Militant and Technological Nation. (London: Macmillan, 1991)

Edward W. Constant II. The Origins of the Turbojet Revolution. (Baltimore: John Hopkins University Press, (1980)

Eric Brown and Dennis Bancroft. Miles M.52: Gateway to Supersonic Flight. (Stroud: Spellmount, 2012)

John D Anderson Jr. A History of Aerodynamics and its Impact on Flying Machines (Cambridge: Cambridge University Press, 1997)

Sterling Michael Pavelac. The Jet Race and the Second World War. (Westport: Praeger Security International, 2007)

Takehiko Hashimoto. Theory, Experiment, and Design Practise: The Formation of Aeronautical Research, 1909-1930. (Ann Arbour: UMI Dissertation Services, 1991)

The National Archives – AVIA 15/1908


[1] Rivas B. (2012)

[2] Brown E (2012)

[3] Constant E W (1980)

[4] Pavelac S M (2007)

[5] Edgerton D (1991)

[6] Edgerton D (2011)

[7] Anderson J D Jr (1997)

[8] Snow C P (1962)

[9] Edgerton D (1991) pg. 107

[10] Hashimoto T (1991)

[11] Anderson J D Jr (1997) pg. 383

[12] Anderson J D Jr (1997) pg. 385

[13] The National Archives (In future to be abbreviated to TNA) – AVIA 15/1908 – 15A – Extract from POW Report

[14] TNA – AVIA 15/1908 – 9A – May 1943 Correspondence between DSR and CRD at the MAP

[15] TNA – AVIA 15/1908 – May 1943 RAE Report ‘Some Simple Considerations of Supersonic Flight’

[16] Rivas B (2012) pg. 218

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