The saga of Mayo's Composite Aircraft projects

Schneiderman

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Major Robert Mayo, aviation consultant and General Manager (Technical) at Imperial Airways Ltd (IAL) conceived the idea for a composite aircraft, the lower component serving to enable take-off of the heavily-loaded upper component, which was carried on its back. The concept, and the operation of the key attachment and release mechanism, was patented in 1932 with follow-up patents in 1933, 34 and 36.
Short Bros were invited to tender for both aircraft in 1933 (there does not appear to have been a competitive tendering process) and they carried out some preliminary tests and calculations which were presented to Mayo, IAL and the Air Ministry. IAL and the Ministry agreed to finance the construction of aircraft, for which they drew up spec. 13/33. Shorts submitted their final proposal in September 1934 and were authorised to proceed.
The two aircraft, Maia, a seaplane, as the lower component and Mercury, a float plane, as the upper component were flown in 1937 and achieved the first separation in early 1938. This and subsequent tests were all successful and proved the concept.
Mayo, naturally, was keen to sell the composite concept for other applications and came up with a variety of ideas, both commercial and military.
After Maia/Mercury had proven the viability of the concept Short were asked to tender for a landplane upper component, basically a landplane version of Mercury, for use as a trans-Atlantic or Empire mailplane. Three and four-engined options were tendered; either to be carried by one of IAL’s Armstrong-Whitworth Ensigns re-engined with Armstrong-Siddeley Deerhounds. However by this point IAL were losing interest in the concept and the Deerhound was proving problematic; the flight test aircraft was lost in a crash.
In 1939 Mayo made tentative suggestions for two further mailplanes; a small one to be carried by a DC3 and a medium size one to be carried by a DC4. Nothing came of this.
On the military front Mayo saw the composite as an ideal way to launch a small, high-speed, long-range, bomber. In 1935 Gloster were asked to submit a design for a two-man bomber with a range of 2000 miles carrying 2000lb of bombs. No lower component was specified by Mayo. In Gloster’s tender it is implied, but not stated, that Mayo had specified a single engine. Gloster’s calculations showed that the idea was flawed, the performance of the heavily laden bomber required separation at high speed and high altitude, both considerably above those to be assessed by Maia/Mercury. The project was dropped. Mayo, however, was not deterred and continued to push the concept in 1936 and again in 1939, suggesting a performance by the bomber far in excess of that estimated by Gloster, but without explanation. The lower component would be an Armstrong Whitworth Whitley MkIV.
In 1940 he tried again, but now focussed on reconnaissance applications and suggested a 25,000 lb aircraft with two or three-engines, total of around 1700 hp. This, too, fell on deaf ears.
But then things took a turn for the better. In late 1940 Air Commodore Marix, of Coastal Command, asked whether it would be feasible to carry a Supermarine Spitfire on the back of a Whitley. The idea was to patrol up to 500 miles into the North Atlantic and to launch the Spitfire against prowling anti-shipping aircraft. The Spifire could then fly back to land after the engagement. Mayo responded in the positive. The project was then redefined to be a Hawker Hurricane carried by a Consolidated Liberator, and this was given sanction to proceed at the end of 1940. Hawker produced drawings for the modification required for the Hurricane; mounting points, control locks, enlarged oil tanks etc. while Rolls-Royce collaborated on the system to enable the Hurricane to draw fuel from the Liberator. Shorts in Belfast commenced work on the cradle and other parts required for fitment on the Liberator. All seemed to be proceeding well. In early April Hawker had nearly completed all the new parts and a Hurricane had been selected for modification and would arrive shortly. The modifications were expected to take one week. However there was no sign of the Liberator and Shorts were unable to complete their work until it arrived when they would be able to make a detailed assessment of its structure. The Air Ministry, or Ministry of Aircraft Production, for reasons unknown, pulled the plug, leaving Mayo to send one last desperate letter hoping to get the decision reversed. The project was dead.
Nothing more was heard of Mayo’s Composite Aircraft concept.
 

lark

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Highly interesting !
There also the thread - British 'Mistel' combination projects - on
this sub-forum.
 

Madoc

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Now that would've been quite the sight!

A big ol' Liberator, in Coastal Command colors, lumbering along through through the low clouds out over the North Atlantic - and with a Hurricane perched atop the bomber's back!

Wouldn't that have been a nasty surprise for any Condors skulking around hunting for convoys! Nasty to, I suppose, for any U-boats as the more nimble Hurricane could keep the sub's gun crews thoroughly distracted while the bomber set up for its attack run.

At the very least, it'd make for a helluva model build!
 

Tony Williams

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I have some photos which I took on a visit to Dundee about a year and a half ago. I was walking by the Tay Estuary and happened to see this commemorative plaque, concerning a world record long-range flight by the Mayo composite aircraft in 1938.

Mayo3.jpg


Mayo2.jpg


Mayo1.jpg
 

lark

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I think it's also worth to mention the

Folland/Mayo High-speed Long-range Bomber monoplane
upper component .(1935)

described in :
The Aviation Historian issue No 11
Follands Forgotten Monoplanes part 3- Ralph Pegram.
 

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I am slowly sorting out a large amount of paperwork, scattered throughout twelve boxes, from the office of Mayo that was donated to the Royal Aero Club. The rough outline of the composite aircraft story is as I described in the first post of this thread but I will fill in more detail as I read my way through the files, which will take a couple of months or so. The best way is to do this year by year, starting with 1932 (see next post)
 

Schneiderman

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1932

In 1927 Imperial Airways (IAL) decided that in future all air mail throughout Empire should be carried by dedicated aircraft rather than as cargo on passenger flights. The Air Ministry and Imperial Airways then issued spec. 21/28 in the summer of 1928 which called for designs for twin-engine aircraft capable of carrying 1000lbs of mail for 1000 miles at a cruising speed of more than 150mph. The financial collapse in 1929 and onset of the Depression resulted in the project being given low priority and the somewhat similar outline specification for a single-engine high-speed bomber led to the submission of several designs unacceptable to IAL, who eventually awarded a contract to Boulton-Paul. Their tender, in 1931, was the P64, a twin-engine biplane that barely met the minimum requirements. IAL continued to look for a more advanced aircraft.
In 1932 Maj. Robert Mayo, technical advisor to IAL and responsible for drawing up most of their specifications, thought that he had a solution to the problem. In April he submitted a patent application.
Patent GB400292A described a Composite Aircraft where the heavily loaded mail carrier (upper component) was carried on the back of a second aircraft (lower component) that served solely to manage take-off and climb to altitude where the aircraft would separate. In this way the upper component could be optimised for high-speed cruise with a full load without being compromised by the need to take-off on its own. Although this concept was not entirely novel the key was in the methods and mechanisms to ensure a safe and positive separation of the two aircraft. To this end an additional patent, GB402895A, was issued refining the separation procedures. In essence, at an appropriate altitude and speed the lift generated by the upper component exceeded that by the lower component so that when the connection was released a safe separation was assured.
 

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Tony Williams

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Are you thinking of putting all of this together in a booklet for publication?

If so, you would be welcome to use my photos above if you wish - I have much higher-res versions.
 

Schneiderman

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Tony Williams said:
Are you thinking of putting all of this together in a booklet for publication?

Hi Tony,

Thanks, I had thought about writing an article for publication but decided it was probably better to place the whole story here. That way I can add new material as it becomes available and others can contribute if they wish.

Cheers
 

Schneiderman

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1933

Mayo

Refinement of the separation system continued as Mayo considered the effects of selecting different aerofoils for the upper and lower component. Not only could that for the upper component be optimised for high-speed cruise, as no compromise need be made to allow for take-off, but the different lift characteristics of the two aerofoils could enable separation to be achieved automatically beyond a certain speed. Patent GB402951A was awarded.
Discussions were underway with Arthur Gouge at Short Bros regarding the appropriate design of the two component aircraft. Mayo also negotiated with IAL and the Air Ministry to obtain funding for the project, and was successful in obtaining approval. An outline specification, 13/33, was issued to cover Short’s work. The specification stated that both components should operate from water as much of the planned mail routes were over sea and the policy of IAL was to focus on flying boats for much of the Empire network. The upper component would carry 500lb of mail at a cruising speed in excess of 150mph with a range of over 2350 miles against a 30mph headwind, sufficient to cross the Atlantic. To maximise the utility of the aircraft the lower component was expected to function as a commercial aircraft when not part of the composite. The specification required that the upper component be powered by four Napier Rapier IIIs and the lower by two Rolls-Royce Buzzards. Almost certainly these were to be the Buzzard MS, rated at 1000hp, as there are specs and blueprints for this version, and not the basic Buzzard, in Mayo’s files. Both of these engines were relatively experimental at the time and suggests that the Air Ministry considered the Mayo project, itself experimental, as a useful opportunity to evaluate the engines.

Short Bros

The Composite Aircraft projects were numbered S20 for the upper component and S21 for the lower.
In addition to their early work on Mayo’s project Shorts were aware that IAL would soon issue a draft specification for a four-engine, monoplane flying boat to operate on the Empire routes and had commenced preliminary design of such an aircraft under project S23. This became the ‘C’ class. They had also received Air Ministry specification R.2/23 for a four engine long range reconnaissance flying boat, their design for which was assigned project number S25. This became the Sunderland.
Arthur Gouge had a good track-record in flying boat design having the Calcutta and Kent in service with IAL and the Singapore III under development for the RAF. The large Sarafand prototype was under evaluation at the MAEE. New concepts in planning-bottom design were being investigated in Short’s water tanks. (Gouge described his work on the evolution of flying boat design in a paper presented to the RAeS in December 1936 and published in the 17th Dec issue of Flight)
 

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Schneiderman

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1934

Mayo

While Shorts worked on their tender for the Composite Aircraft Mayo concentrated on finalising the outline specifications for four-engine flying boat and four-engine land type plane for operation on IAL’s Empire routes, which were issued in March and May respectively. These specifications were very similar as they both called for aircraft carrying either 6200lbs of freight, 24-28 day passengers or 16-20 night passengers. Minimum cruising speed was to be >130mph and range >500miles against a 40mph headwind. In both cases it was stated that any engines in the 500-750hp range could be selected but that geared air-cooled types were preferred. Curiously the flying boat spec. requested a detachable undercarriage that could be fitted while afloat to allow the aircraft to be flown as a land plane. This requirement was dropped later. In early 1935 the landplane contract was awarded to Armstrong-Whitworth for the Ensign and the flying boat contract went to Shorts for their S23 design.
At the very end of the year Mayo draughted a further patent, GB445829A, covering additional refinements to the release mechanism; a barometric lock that prevented separation below a pre-set altitude.

Short Bros

Gouge responded with a tender for the Composite Aircraft to meet spec. 13/33 in September 1934 after having carried out detailed stress analysis and model testing of his two aircraft designs. For the upper component he advocated changing the Napier Rapier III to the V version, which was supercharged and gave superior performance in range. The design for the upper component, S20, appears, from the description, weights and dimensions to be very close to the aircraft as eventually constructed but the performance figures later improved considerably. Gouge also concluded that two R-R Buzzards in the lower component provided insufficient power to ensure a satisfactory take-off in its secondary role as a commercial flying boat (see original S21 design) and substituted four Bristol Pegasus PE4M air-cooled radials. However the entire design of this aircraft was to change, and there were good reasons for Shorts taking this position. Artwork by G H Tavis, dated 1934, and published in The Illustrated London News and Flight the following year, quite possibly gives a fair indication of how the earlier design would have looked.
Gouge had worked closely with Mayo through 1933 and was well aware that he was in a strong position to secure the order for the Empire flying boat. The S23 design was well in-hand prior to the release of the final specification. Here was an obvious opportunity to reduce design and development costs of the S21 lower component by dropping the original concept and replacing it with one that shared many features and parts with the S23.
 

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Schneiderman

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1935

Mayo

The year started with Mayo taking a long, hard look at a patent application filed by John North, chief designer at Boulton Paul. This, too, described a composite aircraft but in this instance the heavily loaded primary aircraft, a monoplane bomber, was assisted in take-off and climb by a lightly loaded secondary aircraft mounted on its back. Although this was the inverse layout to Mayo’s concept he made the case that his patent covered both options, which was certainly not clear. Both systems had their merits and weaknesses; in North’s case the downside was that the primary aircraft, most especially the undercarriage, had to carry not just the heavy bomb overload but also the weight of the secondary aircraft. Versions of North’s idea cropped up several times over the coming years, most visibly in an article written by Noel Pemberton Billing for Flight in 1940.
Convinced of the great potential of his system Mayo launched a company to manage the commercial rights of his patents, with ownership transferred to the company. Mayo Composite Aircraft Company Ltd was established in March 1935 with an illustrious board of directors, including Sir Harold Snagge (Chairman of Napiers), Hugh Burroughes (Chairman of Gloster) and Air Vice-Marshall Borton. The Company commenced negotiations to sell the rights overseas, establishing contacts in Germany, Russia, Japan and the US

The existence of the Short-Mayo project had leaked in the closing weeks of 1934 and in late 1935 articles began to appear in the aviation press, but Mayo himself did not contribute, at least not directly. C M Poulsen, editor of Flight, wrote an article for the 7th November edition and two weeks later he was able to publish an artist’s impressions of the composite taken from the Short’s report of their Annual General Meeting. Finally, in December, a detailed model was presented at the Empire Airways Exhibition. The concept generated a great deal of interest and more than a little scepticism.
The Composite Aircraft in its commercial form was primarily about range. The upper component had to land carrying it paying load and the only weight lost during the flight was the fuel burning-off. This set a minimum size for the aircraft if wing loading was to be at a safe level for landing. For a military role, where the upper component was a bomber, the composite was more about load. As both fuel and payload were lost the aircraft landed empty and hence could be smaller than its commercial counterpart. In theory it seemed straightforward. In the summer of 1935 Mayo approached Henry Folland at Gloster Aircraft with a draft specification for a two-seat bomber carrying 2000lb of bombs over 2000 miles at a speed in excess of 200mph. Mayo subsequently increased the range to 2500 miles. It appears that Mayo’s concept was for a small single-engine aircraft as “ ..economy of material..” was one of the perceived virtues of the concept, although without locating a copy of his original specification this cannot yet be confirmed. Folland’s tenders to this request are described The Aviation Historian issue No 11 but in essence he found that it was not possible to meet Mayo’s full expectations. He made several revisions between November 1935 and June 1936, increasing the size slightly and specifying a more powerful engine, but found that performance was severely compromised; the required altitude and speed for separation appeared to be outside the reach of any available aircraft to be adapted as the lower component and service ceiling with full load was worryingly low. For this class of small bomber the concept had not really proven viable.

Short Bros

Short had won the contract for the Empire flying boats and received an order for 28 without first building a prototype. Gouge had taken the pragmatic step of building the small 4-engine S22 Scion Senior 9-seat passenger aircraft, available in landplane and seaplane form and first flown in 1935, as virtually a scaled down S23 which must have aided confidence in elements of the design.
Short had also won a contract to build a prototype marine reconnaissance flying boat, the S25 Sunderland, to spec. R.2/23 and work on this was also underway.
In mid 1935 IAL issued another outline specification for a four-engined flying boat capable of flying the trans-Atlantic routes (the range of the Empire class had been specified as just 500 miles although the standard aircraft reached 750 miles and plans were already in place to add extra fuel tanks to the S23 to undertake trial long distance flights. A batch of longer range Empires were designated S30). Gouge simply stuck to the S23 design formula and enlarged it in all dimensions as the S26. He submitted his tender in September.
The Empire flying boats and the Sunderland were both high priority programmes and required rapid expansion of Short’s works and the employment of a large workforce of metal workers. The design office was working flat out on the S23, the numerous additions required for the longer range versions, the Sunderland project and the S26. Inevitably Mayo’s composite would take a back seat for a while.
 

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Schneiderman

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1936

Mayo

Notwithstanding the issues raised by Folland’s analysis of the bomber project, in January 1936 Mayo wrote a memorandum extolling the virtues of the Composite Aircraft for launching bombers. In his memorandum he suggests that the Composite Aircraft bomber, with a speed of between 250 and 300 mph, would “..render it practically immune from attack by even the most advanced types of fighting aircraft” and “..it will have for the return flight not only the speed but also the ceiling to enable it to evade almost any form of hostile attack.” Furthermore he makes the claim that once the lower component had returned to base another upper component bomber could be loaded “..within a few minutes.”; a bold statement. The advantages of air-launching a bomber with high wing loading were clear, but, as Folland had demonstrated, not as outstanding as Mayo claimed, and it came with significant downside.

Negotiations for sales to Germany, Russia and Japan continued.

In the memorandum Mayo also states that the Composite Aircraft would be ready for testing in 1936. Apparently he was unaware of the growing workload at Shorts and the higher priority given to other projects. He would have to wait for one more year to see his aircraft fly.
The Aeronautical Research Committee commissioned a study into the relative merits of the three ‘assisted take-off’ methods then under consideration for the trans-Atlantic service, namely the Mayo Composite, inflight refuelling and catapults. The report, T3782, published in July concluded that Mayo’s scheme showed “no marked advantages on any point”, refuelling “..is not, at its present state, suitable..” and favoured catapult systems.

Two new patents were issued; one showing a refuelling arrangement for the S20, and the other further refinements to the latch mechanism.

Short Bros

At the turn of the year the first S23 Empire flying boat was nearing completion and its first flight would take place on 4th July. Production rate was expected to be around one every three weeks. Work was proceeding on the S25 Sunderland prototype while discussions took place with the Air Ministry regarding revisions to the nose and tail armament, which shifted the centre of gravity. Agreement was reached on a number of modifications necessary to rebalance the aircraft, following which a production contract for 11 aircraft was awarded on 11th March.
When early tests of the S23 Empire had demonstrated that its hydrodynamic performance was good and that take-off in less than 60secs was possible at maximum load, despite the high wing loading, a contract for 3 enlarged trans-Atlantic S26 flying boats was also awarded. On top of this Gouge was in discussion with the Ministry regarding a further flying boat type capable of launch by barge-mounted catapult and had a preliminary design in hand. But design work was not focussed solely on flying boats. In response to an outline spec. from IAL for an intermediate size 4-engine airliner he had tendered a design, the S28. Finally, encouraged by his success with large four-engined monoplane flying boats Gouge produced a tender, design S29, to the latest specification for a heavy four-engine bomber, B.12/36. In total this was an extremely onerous workload for both the design team and the construction workers.
Mayo’s optimistic assessment for the completion date of the Composite Aircraft was misplaced.

In 1936 Alan Cobham’s Flight Refuelling Ltd became an associate company of IAL. Cobham held patents for hosed-based refuelling systems and had been experimenting on a small scale for a few years. Now it was planned to run tests of the system using one of IALs modified S23 Empire flying boats, eventually for experimental trans-Atlantic crossings. In early 1936 the Air Ministry issued spec. 36/35 for a long-distance mail landplane, with a range of around 3000 miles, and a contract was awarded to de Havilland for two DH91 Albatross aircraft. This was an all-wood aircraft featuring a composite ply and balsa monocoque fuselage and powered by four DH Gypsy 12 engines. Mayo’s scheme now had two serious rivals.
 

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Schneiderman

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1937

Mayo

Mayo remained largely silent while awaiting completion of the Composite Aircraft.
Negotiations continued with Germany, including meetings with Ernst Udet, while those with other countries seem to have stalled.
By November the finances of Mayo’s Company were beginning to raise concerns and new funds were sought


Short Bros

Production of the S23 was now in full swing and commercial services had begun by IAL. There had been problems, however, as three aircraft were to be lost during the year, one through navigation error in very poor weather and two through pilot error, one on take-off the other on landing. The rushed introduction of an advanced aircraft into service had proven costly. Service experience demonstrated that the planning bottom was rather fragile and required strengthening, and an upgrade programme was initiated. A further eleven aircraft were ordered by IAL, some S23 and the remainder S30.
Plans had been completed for the installation of in-flight refuelling equipment in one of the S23 aircraft and work had commenced.
The first Atlantic crossing by a modified long-range S23 took place on 7th July when it flew from Shannon in Eire to Botwood in Newfoundland, returning on the 22nd. A further nine two-way crossings were made in the year.
On 12th August the Short-Mayo S21 lower component, now named Maia, was test flown for the first time. The S20, named Mercury, followed in mid September.
On 16th October 1937 the prototype S25 Sunderland made its first flight. After brief tests it was returned to the factory for the pre-planned series of modifications.
Shorts had also received an order for two C29 catapult-launched flying boats. These drew heavily on the designs for the S23 and S25 but the opportunity was taken to test models in the RAE wind tunnel and water tanks to assess low-drag, stepless planning surfaces planned for this aircraft and development of the S25 Sunderland.
After extensive taxying trials at differing aircraft weight the first flight of the Composite Aircraft took place on December 20th With the upper component firmly attached to the framework on the wing centre section of the lower component, and with its flight control surfaces locked, the pilot of the lower component was in effect flying an eight-engine biplane. These initial tests were carried out without any problems and Shorts prepared for the first in-flight separation of the two aircraft.
In mid-year Shorts heard that they had won an order for their S29 Stirling bomber. Although rated as less attractive than Supermarine’s Type 317 the Air Ministry, as they had done before in many instance, funded development as an alternative as an insurance against unforeseen problems.

On 20th May the DH91 Albatross made its first flight.
 

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1938


Mayo

Mayo must have been extremely relieved when the Short-Mayo Composite Aircraft achieved its first in-flight separation on 7th February. The event was reported extensively in the press. There had been no technical problems of any kind and both aircraft had behaved exactly as predicted. Later flights were equally successful. The engines on Mercury were upgraded to more powerful Rapier MkVI.

After a series of long-distance test flights, in July, Mercury, launched from Maia at Foynes, flew to Montreal and then onwards to New York carrying 600lbs of freight. The return journey, in the absence of Maia, was made without payload via Bermuda, the Azores and Lisbon.
In October Mercury set a new distance record for seaplanes when it flew 6045 miles from Dundee to the Orange River estuary in South Africa. The original intent to reach Cape Town and capture the absolute distance record was thwarted by bad weather conditions en route, fuel pump failure, and the loss of an engine cowl panel.
In the run-up to Christmas Mercury made two flights to Alexandria, Egypt carrying mail.

Following the successful demonstration of the experimental Composite, Mayo pushed ahead with specifications for commercial versions as landplanes. These would be configured in two forms; Empire and Atlantic. In both cases the lower component was to be an Armstrong-Whitworth Ensign, a type just coming into service with IAL after a protracted development, but re-engined with Armstrong-Siddeley Deerhounds, a new engine still in the experimental stage.
In April Short tendered an upper component design, a straightforward derivatives of the S20 Mercury with a retractable undercarriage. It was to be powered by four Bristol Aquila radials. Mayo was confidently predicting that an order for four would be placed. In March 1939 Short submitted a modified version of this aircraft powered by three Bristol Taurus radials (drawings of these aircraft designs do not appear to have survived).

At some point in the year Mayo wrote yet another brief memorandum with outline specifications for two commercial upper component aircraft. The smaller of the two could have two, three or four engines totalling 750-1120hp, a crew of up to four, loaded weight of 16,000lb, and a cruising speed above 200mph. Depending on range the payload would be between 1100 and 3400lbs. The suggested lower component was the Douglas DC3. The larger version was double the size, and carried 1800-4500lbs of mail. Mayo suggested that it could be carried by the Douglas DC4 (presumably the original design) or an Armstrong-Whitworth Ensign with Wright Cyclone engines.

Now that the Composite concept had been proven Mayo’s Company made a further push to achieve sales overseas. However Germany was cooling on the idea, at least in part as they were committed to catapults. Curtiss-Wright in the US declined the offer. In September they were contacted by representatives from Mitsubishi in Japan. The Japanese Naval Authorities had shown interest in the Composite concept and they were enquiring whether it would be possible to purchase a complete Maia/Mercury composite. As this was not possible, as the design was the property of the Air Ministry, they asked whether it would be possible to buy an S23 Empire flying boat plus a new design for an upper composite to mount on it. As the S23 was not appropriate they asked whether an upper component could be design to fit their Douglas DF flying boat, which Mayo considered to be possible. The discussion went on to consider prices and patent rights.

The odds, however, were stacking up against the composite scheme for commercial use. The official report had not noted any marked advantages relative to the alternatives, most of which were also under development. In-flight refuelling techniques were proving to be successful. Catapult, or accelerator, trials were underway on land, and new long-distance aircraft had flown or were under construction. The Air Ministry looked at Short’s upper component landplane tender to Mayo’s specification but were no longer prepared to fund dedicated mail carrying aircraft, preferring dual-purpose passenger and cargo machines. As a consequence the prospects for the commercial Composite were effectively finished.

The possible military application of the scheme came up again. *Short presented a design to the Air Ministry in April for a single engine, single seat upper component bomber carrying a 2000lb bomb load. The bombs were carried within the fuselage ahead of the cockpit, which was positioned well back behind the wings. The wing plan was reminiscent of Gouge’s flying boats, the Scion and S20 Mercury. This bomber was to be powered by a Bristol Centaurus radial, an engine that had not as yet been tested, even on the bench. Gouge believed that a top speed of 419mph was possible, although the Air Ministry were sceptical and believed it would be around 370mph. Given the loaded weight of 15,500 lb they were probably right.
Further evaluation of the composite system suggested that the time required to load and mount a bomber, take-off, climb to the release height of 15,000ft and return would be of the order of one hour. A hard-working unit may be able to get 20 bombers launched per day, but to get a significant number of bombers on a mission would require a squadron of lower components and several cranes/gantries, which would, themselves, be vulnerable to attack. By August the Air Staff concluded that the use of a composite system was unjustified. To what extent Mayo had been involved in these studies is not known, there are no references to it in his papers archived at the RAeC.

*From Michael Bowyer in Air Pictorial November 1974, presumably from Air Ministry files held in the National Archives (thanks to forum member lark for the information)

Short Bros

Oswald Short and Arthur Gouge had been outstandingly canny. Of the four systems under evaluation for the trans-Atlantic commercial service; Composite, refuelling, catapults and large long-range aircraft, they were in the forefront for each. The Short-Mayo Composite had proven technically viable and they had tendered designs for land-based derivatives and speculatively for military applications. The S23 had commenced testing in-flight refuelling and they had a contract for two S29 catapult flying boats, although this was soon cancelled. Finally the three big S26 flying boats for direct trans-Atlantic crossings were under construction. Whatever decision IAL and the Air Ministry made Short Bros were most likely to be the beneficiary. In terms of the number of aircraft they may be contracted to construct the Composite was probably of least interest to them.

In late 1938 Short tendered a design to specification 14/38 for a trans-Atlantic passenger aircraft. This called for an all-metal, four-engine aircraft, a pressure cabin for sixteen passengers, and range above 3000 miles. Their S32 design drew heavily on the work underway on the S26 flying boat, Sunderland and Stirling. Somewhat to their surprise, given their workload, they were awarded a contract for two prototypes, one with pressure cabin and one without.

With the exception of Mercury’s flight there were no further Atlantic crossings made in 1938 by any of the various long-distance contenders. Although the DH91 Albatross had flown with success there had been no attempts at any long distance flights.
 

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Schneiderman

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1939

Mayo

It was now quite clear that no order for new Composite Aircraft would be forthcoming from IAL and hence test flying of Maia and Mercury was terminated.
Mayo went back to extolling the virtues of the system for a long range bomber. The same arguments were put forward again; speed, range, size, cheap, simple, but this time he suggested in very general terms a two-man bomber carrying two 500lb bombs which would have a range of 2000 miles, with an alternative version carrying four 500lb bombs (i.e. the same as he had requested from Folland in 1935. In these latest cases no defensive armament would be carried. In the draft document he has left the anticipated speed of both aircraft blank. He suggested that the Armstrong-Whitworth Whitley MkIV would be the ideal lower component as it was likely to be obsolete as a bomber by the time the upper component was built and ready for service.

*Independently from Mayo, Maj. Oliver Stewart, the brother of Maj. Jack Stewart, one of the directors of Mayo Composite Aircraft Ltd. and responsible for marketing the Composite, took it upon himself to take up the cause. Why he did so and why Mayo was apparently not leading is a mystery. Stewart wrote to the Technical Directorate at the Air Ministry and requested that they should look again at the Composite scheme, which they did but drew the same conclusions as before. He then wrote to Gouge who informed him that he had carried out no further work on composite schemes. But Gouge then appears to have contacted Folland, now the Managing & Technical Director of Folland Aircraft, and requested that he look again at the possibility. Folland’s design, the Fo111, was sketched out rapidly and sent to the Air Ministry in October. This design was for a two man aircraft carrying two 500lb bombs with a range of 2000 miles, that is to say precisely as suggested by Mayo in his last memorandum, which suggests that there had been some contact between the three of them. The Ministry remained lukewarm about the proposal, which is not surprising as it was no different from earlier suggestions. Exactly how Stewart, Gouge, Mayo and Folland were working is not clear but Stewart contacted the Ministry again and apparently suggested that a speed of 440 mph was possible. The story in the article is a little unclear at this point but the aircraft design illustrated had reverted to being a single seater with wooden outer wings to simplify construction and reduce weight. It was to be powered by a Pratt & Whitney Double Wasp and would carry two 500lb bombs at 440 mph and have a range of 2500 miles. All up weight was estimated at 9655 lbs. The Double Wasp engine had run but was not yet in production. The Ministry were not impressed and the idea stalled.

*From Michael Bowyer in Air Pictorial November 1974, presumably from Air Ministry files held in the National Archives (thanks to forum member lark for the information)

Folland seems to have worked on four bomber designs associated with this project (from Spirit of the Hamble):
Fo111, Nov 1939, unspecified engine
Fo111a, Jan 1940, P&W Twin Wasp (note, not Double Wasp)
Fo112, P&W Twin Wasp
Fo112A Napier Sabre
these last two are probably conventional non-composite versions of Fo111

Now that work with the Maia-Mercury composite had been terminated the focus for trans-Atlantic commercial flights focussed on the Short S30 flying boats with in-flight refuelling and their large stablemates the S26 flying boats, the first of which made its maiden flight on 21st July. The DH Albatross mail carriers were also expected to enter service later. The refuelling tankers were deployed to Foyne and Botwood and eight return flights were made before the outbreak of war terminated all commercial operations.
 

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Schneiderman

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1940

Mayo’s Composite concept as a method to air-launch an overloaded aircraft had been judged to be a non-starter; technically impressive and proven but offering insufficient advantage overall to justify the expense and effort. This was true for both a commercial cargo carrier and a high-speed bomber although Mayo continued to write memos highlighting the potential for bombers, fighters or reconnaissance aircraft. He did, indeed, have a mechanism and technique to carry and launch aircraft, and that still had attractions.

In November 1940 Mayo was contacted by Air-Commodore Marix who wanted to know whether it was feasible to carry a fighter, preferably a Spitfire, as the upper component of a composite. The idea was to patrol around 500 miles out in the Atlantic to defend shipping against attacking aircraft. The Spitfire was to be released when the enemy were spotted and then to fly directly to land once the engagement was complete. Whereas the basic Composite scheme was for the lower component to serve simply to carry the heavily loaded upper to altitude for release, in this case the lower component was to undertake the patrol, and the upper, a standard fighter, only released for combat.
Mayo replied to the query in early December. He considered the scheme to be quite feasible and that the studies and experimentation with the Short-Mayo Composite had gathered sufficient information to enable such a project to proceed without additional work. He recommended that Coastal Commands existing fleet of AW Whitleys would be ideal lower components.

In December the Canadian Director of Air Services wrote a brief memo outlining options for a Trans-Atlantic mail and passenger service. Mayo's Composite was included as one possibility although the prime suggestion was to use Boeing B17s.
 

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1941

Following Matrix’s suggestion and Mayo’s confirmation it appears that a new project was initiated and a meeting held on 23rd January at Short’s offices in Rochester. By this stage the fighter had been changed to a Hurricane and the lower component to a Consolidated Liberator. Mayo was asked to address the issue of weights and separating forces, which he summarised in a note dated 30th January. In a second note dated 5th February he discussed the safety aspects for locking the Hurricane’s controls and the criteria for a safe separation.
A programme of work then commenced with Hawker providing drawings and parts to adapt a Hurricane to be carried, refreshed with fuel from the lower component and fitted with additional equipment to enable it to run for the duration of the patrol; such as an enlarged oil tank. Much of this was ready by the end of March and an aircraft had been selected for modification. Shorts in Belfast were to manufacture the support cradle for fitment on the Liberator.
However a decision was made to terminate the project, although the reasons for this are not recorded, prompting Mayo to write one last note on 4th April to attempt to reverse the decision, or at least to allow the project parts to be stored so that work could recommence at a later date, should circumstances change. Presumably the reply was in the negative.
 

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1942

In July 1942 a question was asked in the House of Commons as to ”..whether any use has been, or is being, made of the Mayo Composite Aircraft for the swift transport of fighters?”
The Under-Secretary of State for Air replied “The possible application of the Mayo principle has been considered from time to time, but other methods have been found more suitable for the purpose to which the hon. and gallant Member refers. To build or to modify aircraft specially for one particular purpose when that purpose can be achieved by readier methods would not be economical. This principle has been considered on many occasions by technical experts, in conjunction with the Air Staff, who know the operational requirements, and if my hon. and gallant Friend wants any further information, I shall be glad to give him further technical details.”

1952

The Mayo Composite Aircraft Company Limited

Extraordinary Resolution (pursuant to section 142 of the Companies Act, 1948) passed 2nd December 1952
At an Extraordinary General Meeting of the Members of the above-named Company, duly convened and held at 3, Thames House, Queen Street Place, in the city of London, on the 2nd day of Decemebr, 1952, the following Extraordinary Resolution was duly passed:-
“That it has been proved to the satisfaction of this Meeting that the Company cannot, by reason of its liabilities, continue its business and that it is advisable to wind up the same and, accordingly, that the Company be wound up voluntarily”
Dated this 2nd day of December 1952

R.H.Mayo, Director
 

Schneiderman

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OK forumites

That is a summary of the Mayo Composite Aircraft story from the Company material held in the RAeC archives supplemented with published material in Flight, Aeroplane, and the Putnam volumes for Short and de Havilland. Additional input from lark who provided the 1974 copy of Air Pictorial.

Comments?

Personally the 'highlights' for me are the interest in the project shown by the Japanese in 1938 (now, why would they want a long-distance bomber? ;) ). Also the fact that contact with Germany went as high as Udet. Finding the Folland Fo111 design in Air Pictorial is also good news, few early Folland drawings are known so it is good that this one has resurfaced. I have no idea why none of this appears in the Mayo files or why the submissions to the Air Ministry appear to have bypassed his company.

It does seem clear that Air Ministry interest in the composite concept declined well before the first flight was achieved. It is also apparent that IAL were more interested in dual-purpose aircraft and put most effort into the Short S23 family and the DH91. Even though Maia and Mercury did all that was expected of them there was basically no market.
 

Cy-27

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Excellent research Schneiderman, I really enjoyed reading the full story having grown up with the Mercury and Maia story in its isolation. I had no idea that the concept extended over such a long period. Thanks again for your efforts.
 

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Thanks for this nice thread Schneidermann... ;D
Do you have some specifications for the Short Bomber?
Thanks
 

Schneiderman

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From the Air Pictorial article, primary source probably in an Air Ministry file.

Short upper-component bomber (April-July 1938)

Bristol Centaurus
Single-seater (i.e. pilot had to fly, navigate and act as bomb aimer, an unreasonably high workload)
4 x 500lb bomb
300 gal fuel
structure weight 4100lb
all-up weight 15,500lb
Max speed 419mph (Air Min estimate was 370 mph)
Range 2000-2500 miles
 

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Hi,

here is the 1934 design.

http://www.avia-it.com/act/biblioteca/periodici/PDF%20Riviste/Ala%20d'Italia/L'ALA%20D'ITALIA%201935%2001.pdf
 

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Schneiderman

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No that is a piece of speculative artwork from The Illustrated London News. See post #12
 

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Here's a brief Movietone newsreel (circa-1937?) about the Short Mayo Composite effort that features some footage of the Short S.20 Mercury (G-ADHJ) under construction, and "mothership" Short S.21 Maia (G-ADHK) taxiing and in flight.
YouTube - British Movietone" "Aviation's Latest"
 

Schneiderman

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Nice video, thanks

A little more on the suggested military applications of the Mayo concept are in a new chapter of Tony Butler's British Secret Projects 4: Bombers 1935 - 1950.
 

TsrJoe

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just musing, is there any note in the files re the serial of the allocated Hurricane (or Liberator ?) intended for delivery to Shorts for the proposed Liberator/Hurricane composite ? im curious if any drawings were prepared for the strut mountings too (there was an artists impression in 'Hurricane Special' but im not sure if the struts depicted are speculative or based upon actual ?)

cheers, Joe
 
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TsrJoe

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ref. 'Hurricane Special', Maurice Allward (artwork by M. Roffe), Ian Allan Ltd., 1975
 

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Schneiderman

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Unfortunately not. A Hurricane for modification had been identified and delivered to Kingston, so perhaps the people at Brooklands could determine which one that was. Apparently preliminary design work had been carried out on the support struts but the structure of the Liberator needed to be examined before final work could be done. I believe the artwork to be speculative.
 

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