Lot 227
Sold for £43,750 (US$ 73,460) inc. premium
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'Special File' comprising approximately 220 drawings, blueprints, specifications, memoranda and letters relating to the production of the Whittle Jet Engine, kept by Henry Nathan Sporborg, senior Director and Chief Engineer of British Thomson-Houston, manufacturers of the engine for Frank Whittle and Power Jets Ltd, under contract from the Air Ministry, between January 1940 and June 1941; the file also containing the draft contract of March 1938 between the Air Ministry and Power Jets, as contractor, and British Thomson-Houston, as manufacturer; the papers contained in the original manilla file bearing a typed label bearing the company's 'B T-H' emblem: "Mr. H.N. Sporborg./ Special File./ Power Jets Ltd./ Quantity Production" and numbered in brown ink "14750"; the spine likewise inscribed "Power Jets./ Quantity Production/ 14750", c. 250 pages, attached with two metal fasteners through filing-holes, some dust-staining and slight time-staining, the outer sheets coming loose, but overall in fine original condition, various sizes, mostly 4to, Rugby, Harrogate and elsewhere, 15 March 1938, and 26 January 1940 to 4 June 1941


  • 'I hope that if you are fully aware of the great importance that the Air Ministry attach to the development of this Whittle engine you will take all steps in your power to ensure that no unnecessary delay occurs in the completion of these engines' – Britain enters the race to build the jet engine during the Second World War. This 'Special File' comprises the papers relating to the development and production of the Whittle Engine belonging to the senior Director and Chief Engineer of British Thomson-Houston, the company responsible for its development and initial manufacture. Few, if any, archives of comparable importance relating to one of the major technological developments of the twentieth century – the jet engine – have we believe been offered for sale.

    Flying Officer Frank Whittle had submitted his first patent for a jet engine as far back as 16 January 1930 but the Air Ministry had shown no interest in his idea. He had also taken his design to the turbine factory of British Thomson-Houston (BT-H) at Rugby and although their chief engineer approved of the idea in principal, it was deemed too expensive to warrant development. It was not until 1935 that Whittle, with the financial backing of Lancelot Law Whyte and others, formed Power Jet Engines Ltd, which was incorporated in January 1936. The Air Ministry still saw no point in the enterprise, so Power Jets entered instead into an agreement with BT-H for them to build an experimental engine facility at Rugby, work on the prototype being well under way by the end of the year. Despite official indifference and a cash crisis, the first 'Whittle Unit' (WU) was produced in 1937. In 1938 BT-H opened testing facilities to Lutterworth and in March that year the project at last received official funding. Meanwhile in Germany, Hans von Ohain's engine, begun in 1935, had passed the prototype stage and was on its way to production (although this was to prove, in technological terms, a dead-end). In June 1939, the BT-H factory was visited by D.R. Pye, the Air Ministry's Director of Scientific Research, who, convinced of the feasibility and importance of the project, gave it his backing. The Ministry agreed to buy the WU and placed an order for a flyable version of the aeroplane. With the new contract, Whittle began work on the Whittle Supercharger Type W1 and in January the Ministry placed an order for a larger engine, the W2.

    One document at least has been marked in pencil "Power Jets Sp[ecial] file 1475", and clearly the documents contained in this 'Special File' – belonging as they do to the man who was both senior Director and Chief Engineer at BT-H – were deemed of especial importance by the company. Bound among papers of March 1940 and no doubt removed from any putative earlier volume, is the original draft costed contract schedule between the Air Ministry and Power Jets, as contractor, and BT-H, as manufacturer; the covering letter to BT-H being signed by L.L. Whyte, Chairman of Power Jets, and dated 15 March 1938 – this therefore being the fruit of the first offer of official funding. In his letter, Whyte states that "We confirm that we have already received from you, through Squadron-Leader Whittle, copies of the negatives and positives of the photographs which are to accompany Squadron-Leader's report, constituting Item 1 under the Research Contract" and stating that this contract will be ready for signature in a few days. The schedule, which extends to eight pages of carbon foolscap, with one typed passage added, is headed "Schedule./ Carrying out of research running on a Whittle Jet Propulsion Unit in accordance with the details, terms and conditions stated below", and opens: "Description./ Supplying all information relating to a Whittle Jet Propulsion Unit (the property of the contractor) obtained from all work undertaken by the Contractor up to and including the 31st July, 1937, including the construction, preliminary investigations and research running of the said unit. The information to be supplied by report in writing to the Secretary (R.D.E.1) Air Ministry immediately. Carrying out research running on the above-mentioned unit at speeds up to 14,000 r.p.m. including 10 hours research running under conditions to be specified by the Director of Scientific Research..."; the penultimate penalty clause reading: "Nothing in these rules shall prejudice the rights which the Secretary of State has otherwise in regard to inventions by Flight Lieutenant Whittle or any undertakings given herein or elsewhere regarding the right of the Secretary of State to control the disclosures of information or to share in the proceeds of commercial exploitation".

    To do justice to this archive a book-length sturdy would need to be written. Rather than attempt a summary of the whole, we instead provide a skeleton outline of the first sixty or so items. These take the story up to late April 1940, when difficulties that had arisen between BT-H and Power Jets were resolved (partially at any rate), with Sporborg submitting proposals for their manufacturing the jet on 20 April to Air Vice-Marshal Tedder, then Director-General of Research and Development at the Air Ministry; while their Turbine Engineer, R.H. Collingham, submitted a list of "Information required from Squadron Leader Whittle" regarding drawings on 22 April; and on 27 April A.P. Young issued a memo which, in effect, launched production: "Manufacture of 'W' Units/ In view of the extreme importance of completing the experimental 'W' units at the earliest possible moment, a special organisation within the Turbine Factory will be set up to handle this work, as shown in the attached organization chart" (for details of Young, well-known as both a management advisor and electrical engineer, see Richard A. Storey, ODNB: 'With some reluctance, in 1928 Young accepted the post of works manager at BT-H Rugby. Hopes he might have had of succeeding H. N. Sporborg, the senior director, were not realized, perhaps because Young acquired too high a profile in public affairs for a company man').

    The file opens with a memo by H.N. Sporborg to his colleagues, dated 26 January 1940: "Mr Whyte of Power Jets was here today and emphaised [sic] the fact that their work is now looked upon as of the greatest importance by the Air Minister, and in other Air Ministry development work... He also asked whether we did not consider that the time had come to put a co-ordinating engineer on the work, and I immediately said that I thought Mr Cheshire would be an ideal man... Mr Whyte smiled and said that he did not think that would be agreed to by Mr Whittle". This is followed by the original incoming letter to Sporborg and his colleague signed by D.R. Pye, Director of Scientific Research at the Air Ministry, dated 27 January 1940. This is headed "Whittle Jet Propulsion Engines", and opens: "You have for some considerable time been associated with the research being carried out by Power Jets Limited on the Whittle engine the position being, I believe, that all the design work and manufacturing processes are carried out in your Rugby drawing offices and workshops. During the last few months of this research the results obtained have been extremely promising, and the Air Ministry have now decided that further engines should be built on a high priority... I hope that if you are fully aware of the great importance that the Air Ministry attach to the development of this Whittle engine you will take all steps in your power to ensure that no unnecessary delay occurs in the completion of these engines and that you will do all you can to assist Power Jets Limited in their work", and suggesting that engineers be transferred to Ladywood "where the design could then be concentrated under Squadron-Leader Whittle's personal attention". By 21 February, Sporborg is addressing a memo to his colleague, notifying them that Tedder had taken over supervision of the project from Pye and that "As a result of this change they expect that orders will be placed very soon for anything from 4 to 12 new engines based on the design of the W2 engine" and that "it was the Air Ministry's view that the firm who will be engaged on quantity production later on of these engines should be the firm that would carry out the development work, and, therefore, the firm with whom the orders for developing engines shortly to be ordered will be placed". This is followed a terse memo, initialled by R.H. Collingham, the turbine engineer: "Power Jets./ Whittle Engine W.1. S.H.P. to compressor 3000./ If plane at 500 miles/ hour at ground level, H.P. = 1383.5./ Thrust at ground level at standstill = 1260.5 lbs./ R.H.C.".

    Thereafter, we have: a duplicate memo from A.P. Young to Collingham, opening: "Confirming our conversation of this afternoon, I understand that an order is likely to be placed in the immediate future for 8 – W.2. Engines to be completed by the end of this year", 22 February 1940; a memo signed by W.A. Randles, 23 February, opening: "This memo covers work done on the re-design and conversion of the Experimental Engine and the new engine known as W.1. This work is so interwoven that it is not possible to separate the two engines"; blueprint graphs and accompanying memo of 23 February: "The attached graphs show the actual position to date and our programme for completing outstanding work in connection with the Experimental Unit and Whittle Engine No: 1... Dealing with Graph No.1 the actual manufacturing position is as follows:-/ K. 802117 Spare Rotor/ Stub Shaft and Blading complete./ Quill Shaft machined complete, and now at Messrs Herberts or mating with Stub Shaft. Delivery promised for 8th March, 1940. This Rotor will be assembled complete, and balanced by the 29th March, 1940./ K. 802218 Modification to Existing Unit./ Blower Casings, joints planed, drilled and bedded./ Air Discharge Pipes, Die Castings received 25% ground"; a memo signed from Collingham to Sporborg, 23 February 1940 headed "Power Jets Limited" discussing "the redesign and conversion of the experimental engine, and of engine W.1." and "engine W.2." of which "we have ordered the main forgings for the turbine & compressor"; another signed by Collingham, on their agreement with Power Jets and their understanding "that it is proposed to make each of the engines slightly different, but the differences will only be of minor modifications, such as modifications to blade angles, etc", with the coda added – "the promise given by Squadron Leader Whittle at the meeting on the 24th inst., that complete information on vapouriser, main & pilot jets, flame tube holes, and fuel connections, will be supplied by the 30th April"; further letters concerning the dispute between Power Jets and BT-H over the eight trial engines; a letter signed by L.L. Whyte to Sporborg: "You have confirmed that your Company has no existing facilities for quantity production. The placing of military orders is not within our control, and in any case we share the view, which we understand to be that of the Air Ministry, that your Company is not suitably placed for war-time aero-engine manufacture"; a memo initialled by Whyte, stating that the name 'Whittle Gyrone' has been registered as a trademark ("...An obvious element in the novelty of the Whittle Engine lies in the fact that it is not the equivalent of an Aero Engine, but of an Aero Engine plus Airscrew..."), 1 March 1940; a letter signed by Air Vice Marshal Tedder, to Sporborg, headed "Whittle Engine and discussing problems between Power Jets and BT-H ("...My discussions with Mr Whyte of that Company have reached the stage when it is desirable for the position to be put on more formal lines..."), 6 March 1940.

    Tedder's letter leads to a memo by Sporborg on his discussion with Mr Pickles of the Air Ministry held at Tedder's behest ("...I told him that we had been working with them, helping their development, for the last four years, that we had done all that we could to help them, and without expressing any opinion as to whether the work could have been done in less time or not we nevertheless found that they were not practical manufacturing people, and therefore had had to be as patient as we could with them... I told him that there was no one in the Power Jets Company who had any practical experience in this class of work, that Mr Whittle came to it as a young man from College, that we had done all that we could to help him, that Mr Whyte himself had stated that he was an amateur and had no engineering or manufacturing experience, and that therefore I did not think the Air Ministry ought to form any view as to what the B.T.H. Company could do from statements made to them by Power Jets... He laughed at this and said that he had been handling contracts with the B.T.H. Company in the Contracts Department for a good many years, and it was not necessary for him to make a visit..."), 7 March 1940.

    (The schedule and covering letter of 15 March 1938 – see above – are bound in at this point; they come with a memo to Sporborg by the Manager of Turbine Sales of 2 April 1940: "It was agreed... that the original of Power Jets Limited letter of the 15th March, 1938... together with the Schedule setting out the terms and conditions of the proposed Air Ministry Research Contract, should be filed by you).

    The narrative resumes with a memo initialled by Collingham of a conversation with Whittle ("...Squadron Leader Whittle called in at office to discuss details on Engine W.1 and afterwards in general talk on Power Jets future ideas on development...They were proposing to develop a gas turbine driven blower, the turbine being single stage and blower two stage... The proposed to build what they termed a W2X engine, leaving out considerations of light weight except as regards impeller... 6000 S.H.P. gas turbine for driving compressors for full scale test on compressor performance... 4000 S.H.P. gas turbine driven generating set for emergency use for Air Force to compete with Brown Boveri design... Whittle stated that he would feel forced to advise Air Ministry that limits of accuracy obtained in manufacture in Turbine Factory not close enough for work of this nature..."), 18 March 1940; a letter signed by Whyte of Power Jets to Sporborg, opening: "At one of our recent meetings you explained that the B.T.H. Company would not be prepared to continue the manufacture of Engine W.2 unless the remainder of the Development Engines (required by the Air Ministry for possible military use) which are planned for this year were also to be manufactured by them", 18 March 1940; a retained carbon initialled by Collingham of his letter to Whittle, refusing to let him have a list of the W.1. drawings ("...this engine will not be completed for test before the middle of June... and in fact the assembly drawings, as you are aware, are not yet completed..."), 20 March 1940; a letter signed by Whyte of Power Jets, to Sporborg, giving details of two experimental Gyrones that they might manufacture, 21 March 1940; a memo by Sporborg, opening: "I called on Captain Wilkes, Managing Director of the Rover Company [who were to be manufactures of the W2B engine], at their Meteor Works in Coventry to-day by arrangement to discuss the Whittle Engine... He has discussed the matter in a general way with Air Vice-Marshal Tedder and was present at the conference in Harrogate on the 16th. He understands that the Ministry want him to build the engine... They expect to be given an order by the Air Ministry for a good number of engines... Rover Company have never done any turbine work of any sort, but assume they will be able to build the engine from the drawings. They would like to have our help", 28 March 1940; a memo by Collingham to Sporborg, discussing the two experimental Gyrones ("...If we are going to get out the drawings for the W.2. engine before we go ahead with the drawings for this experimental Unit, we could not start the drafting work before 27th May..."), 3 April 1940; a memo signed by A.P. Young, to Sporborg, headed "Power Jets Limited – Manufacture of Whittle No. 2 Engine", with attached schedule and blueprint graph, the memo opening: "In accordance with your request we have examined in some detail the proposal to manufacture the Whittle No. 2 Engine at the rate of one per week. We are unable to finally determine this problem at this stage because as you know the final design of this new engine have not yet been completed", 4 April 1940; a letter signed by Whyte of Power Jets, to Sporborg: "you stated that the B.T.H. Company were prepared to proceed immediately with the manufacturing drawings on W.2, but that your Company maintained the position that if the next batch of engines were not coming to them, they would not be prepared to undertake the manufacture of W.2. You also said that if you did not complete the manufacture of W.2 you would not be prepared to hand over your manufacturing drawings to another Company. In view of the importance of these matters I have notified the Air Ministry regarding these points"; with Sporborg's draft reply pencilled in, 4 April 1940; a typescript of Sporborg's telegram to Whyte ("...I do not accept your letter fourth as correct record...") and a letter signed by Whyte, in response to Sporborg's telegram, 5 April 1945.

    There follows a receipted list of engineering drawings received from BT-H by Power Jets, 5 April 1940; a memo signed by J.L. Wilson to Sporborg, headed "Whittle Engine ("...Air Vice-Marshal Tedder telephoned me... He asked me if it was possible to have a short meeting during lunch time, as the Whittle Engine was one of the subjects of conferences today... I stated that our recommendation would be that the bulk order for engines be split between the B.T.H. Company and the Rover Company... Air Vice-Marshal Tedder agreed whole-heartedly with these views and stated that the chief anxiety of the meetings being held to-day was to see how soon trials for this engine could be made in the air..."), 8 April 1940; a carbon of Sporborg's letter to Tedder ("...We have fully considered the matters discussed with you at our previous meeting with regard to the Whittle Engine... and we are in a position to make definite proposals..."), 8 April 1940; a carbon of Sporborg's letter to Whyte ("...I am at a loss to understand why you considered you had any authority to tell the Air Ministry anything as the result of our conversation..."), 8 April 1940; a letter signed by Whyte to Sporborg, in answer to the above, 10 April 1940; a memo by Sporborg headed "The 'Whittle Engine'", opening: "A meeting took place at Rugby today between Mr Tweedy and Mr Tobin of the Air Ministry, Sqd Leader Whittle of the Air Ministry who is on loan to the Power Jets Company, and Mr Wilson, Mr Collingham and myself, to discuss details of the arrangements proposed under which we are to more actively assist the Air Ministry in the development of the Whittle engine" ("...We pointed out that the Whittle design is entirely untried and would involve a good deal of draughting work and pattern making... We said we feared that if the WX. design were proceeded with it would have to follow the completion of the W.2 engine, whereas our design could be carried on in parallel... The Air Ministry representatives made it clear that they wanted to enlist the assistance of the B.T.H. Company to bring to bear on this problem our accumulated knowledge and experience of the subject, and they pointed out in a private conversation after the meeting that if we had any difficulties with Mr Whyte or Sqd Leader Whittle in doing this, we were to enlist their help if we required removing any such difficulties..."), 15 April 1940.

    That same day a meeting was held at BT-H, chaired by Sporborg and attended by Whittle, of which we have the minutes ("...the Air Ministry was proceeding under the assumption that the work might be got through in time for the this war and it was only on that assumption that they were justified in putting extreme pressure on the work... After a brief description of W2.X. had been given by Squadron Leader Whittle, Mr Tweadie wanted to know whether the W.2,X, and W.X. would be manufactured in parallel... Squadron Leader Whittle explained that the drawings for W.2 were nearly completed and that the patterns, with one exception, have been made..."), 15 April 1940. There was clearly a good deal of bad blood by this time between Whittle and BT-H, as a memo by Collingham to Sporborg shows: "Mr Randles took the opportunity to ask S/L Whittle when he could discuss various discrepancies which he had found in the layouts, and S/L Whittle... stated that we were wasting our time as the layouts were not up-to-date... I rang S/L Whittle up to-day and asked him what he meant exactly by saying that we were wasting time, and he stated that he had not put it as bluntly as this... It was his understanding that the drawings for engine W.2. would be made at Lutterworth as he was responsible for design to the Air Ministry, and that prints of these drawings would be sent to Rugby for our comments... He also stated that he felt unless this question of drawings and design was dealt with on these lines that he would not be prepared to accept responsibility to the Air Ministry. I told him that he was raising questions which it was not within my province to decide, and that all such matters would have to be taken up with Mr Sporborg", 17 April 1940. Nevertheless, this is followed in the file by a copy of a letter by Whittle to BT-H, sending prints of drawings ("...The layout drawings shewn are preliminary proposals for the single chamber pressure combustion test unit which we refer to as W.X..."), 17 April 1940; a copy of a letter by Whyte to BT-H, concerning orders and spares for the W1, 17 April 1940; a memo headed "Proposition to Manufacture the W.2 Engine on a Production Basis", with covering letter signed by A.P. Young, opening: "The proposition has been studied in detail on the basis of our receiving an order for at least 125 engines to be manufactured at the rate of 2½ engines per week"; with three attached schedules, blueprint of the workshop and graph, 18 April 1940. Clearly some sort of rapprochement had been arrived at, as a copy of a letter by Whittle to BT-H, headed "W.X. Engine", shows: "We desire to reproduce the combination chamber conditions of the Power Jet engines at all the usual running speed, and hence the set to do this must be variable in speed over about a 10-1 range", 19 April 1940. Subsequent papers testify that a working relationship had been re-established, such as a quotation signed by H.G. Rowe, Manager Turbine Sales, submitted to the Ministry for the Whittle Engine W2 (three for £14,480), 20 April 1940; two letters signed by W.L. Tweedie of the Ministry, to Sporborg, concerning the contracts, 20 April 1940; a carbon of Sporborg to Tedder, headed "Whittle Engine", outlining the building work, etc., required, coming to £200,000, 20 April 1940; and a memo to Sporborg signed by Collingham, headed "Whittle Engine W.2./ Information required from Squadron Leader Whittle", 22 April 1940.

    This concludes our survey of the first sixty or so items. The remaining papers are no less interesting, concerned as they are with the minutiae of development and production, and include at least five pencil engine-designs by Collingham, the turbine engineer, as well as a run of requisition orders submitted to Sporborg, and often lengthy production reports. The 'Special File' ends on 4 June 1941. By then aircraft production had been transferred from Tedder's control at the Air Ministry and made part of a new Ministry of Aircraft Production under the control of Lord Beaverbrook, and the Gloster E.28/39, powered by a single Whittle W1, had had its maiden flight on the 15 May 1941. The volume concludes with three letters or memos. The first is from Whittle (a carbon copy) to BT-H, Turbine Sales, dated 30 May 1941, headed "Whittle Superchargers – Turbine Design", opening: "In recent work on the test bench it has been found that the turbine of the W1A is much less efficient than that of the W1 and that the W1 No.2 design of blading is also less efficient than the first design. The Ministry of Aircraft Production has been informed of this and of our view that an intensive programme of experimental work is required on the turbine component of the supercharger within the next few weeks, if the W2B (Rover) is to be launched into production in time to keep up with the aircraft production. We are of of the opinion that you could give very considerable help in this matter: (1) by making alternative blading and alternative wheels for the W2 Mk III and W.2.B. (Power Jets); (2) Wind tunnel tests". This request gives rise to the penultimate document, a memo to Sporborg signed by Collingham of 3 June 1941 in the course of which he states: "I feel we should not carry out any of Wing-Commander Whittle's suggestions or proposals which we feel that our experience in design of turbine blading will not assist the development". The final letter is the retained carbon of Sporborg's reply of 4 June 1941: "We cannot refuse to help them, but as you say it must be clearly understood that nothing whatever should be undertaken that will cause any delay of any sort to the completion of our W2B machine, no matter what pressure may be brought to bear on us by the Ministry, or anyone else".

    Provenance: purchased by the present owner in the early 1980s. We are grateful to the Bodleian Library, Churchill College, Cambridge, and the National Archives for their help in researching the provenance.

    End of Sale.
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  1. Simon Roberts
    Specialist - Books, Maps, Manuscripts and Historical Photographs
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