From "Weaver" to "Ace".
The Gloster Single-engined Jet Projects
The Gloster E1/44 single-engined jet fighter, the result of project "Ace"; too late for WW2, too early for the Cold War.
In Britain, the invention of the gas-turbine jet engine as a means of powering aircraft is usually credited to Frank Whittle. Amongst many other claimants are the German Hans von Ohain, and the Frenchman Maxime Guillaume (even in Britain, there is another contender, Alan Arnold Griffiths). In truth, the gas turbine is one of the simplest sorts of propulsion imaginable, its adoption many years earlier only being held back by a lack of metallurgical knowledge of how to withstand the heat involved. It is interesting to speculate that, if we ever do make radio contact with other advanced life-forms in our Galaxy, many might have skipped over either the steam engine or internal-combustion engine (or both) and gone straight to the much simpler gas turbine, if they had the requisite alloys or exotic ceramics available. Anyone who remembers the "Scrapheap Challenge" TV show will recollect jet engines being built from scratch (for example see the second half of the YouTube video at <this link> ) but those engines would only run for a minute or so before either disintegrating or melting. Advances in making alloys more resistant to the increasing heat in high-performance piston aero-engines¹ made it possible for Whittle to demonstrate a jet engine that worked for over 20 minutes and it was this that prompted the Air Ministry, in 1939, to order an experimental aircraft to try this new engine in.
With war looming, most British aircraft companies had full order books and design staff already committed to other projects. The choice fell on Gloster aircraft, and their chief designer, George Carter. The Gloster company had been swallowed up by the Hawker-Siddeley Group in 1934 but fortunately, a full design team was retained, despite losing Gloster's star designer Henry Folland. It has been suggested that the initial choice of Glosters was prompted by the belief that the design they had most recently been working on, a twin-boom pusher design in response to Air Ministry Specification F18/37, similar in layout to the later SAAB 21, could be easily converted to use a jet engine (the SAAB 21 was successfully redesigned to use a jet engine as the SAAB 21R) . Whittle first met Carter at the Gloster factory in April 1939, where Carter was told about the secret engine project. Carter was intrigued by the idea of a jet aircraft (apparently Carter himself had patented an idea for a gas turbine engine when he was 22 ²) and started looking at design studies prior to an official contract with the Air Ministry. This was agreed in the following October with Carter pitching two alternative designs to the Air Ministry specification E28/39, the whole project being given the code name "Weaver".
The first design was surprisingly prescient, combining a streamlined fuselage with a mid-wing, very slightly "gull" wing. It featured a teardrop cockpit canopy. Two air intakes for the jet engine were located low-down on either side of the nose and the jet engine exhaust exited at the rear of the fuselage via a long tailpipe. The design had a tricycle undercarriage with a nose wheel, then still a novelty in British aircraft. It was a very futuristic design, especially considering the last Gloster design to reach production had been the biplane Gladiator.
First outline design for project "Weaver". Remarkably advanced for the time with nosewheel landing gear and long tailpipe.
The second design put forward was more reserved, in that it avoided any unforeseen problems with the long tailpipe by having the tail end in an overhanging boom. It had a single air intake at the front of the fuselage and the cockpit canopy was faired into the spine that joined the tail boom. This design solution was very close to that adopted by the Soviet Yak 15 and Mig 9 early jet fighters.
Second outline study for project "Weaver" produced a design similar to the first Soviet jets
Although experimental, both designs were intended to be converted into short-range interceptors with minimum armament for use in an emergency. The first design with machine guns mounted in the nose, the second with a single 20 mm cannon in a small fairing lip above the air intake.
Perhaps surprisingly, the more ambitious first design was chosen for development. It evolved into the E28/39 "Pioneer", losing the twin air intakes in favour of a single large opening in the nose of the aircraft.
Replica Gloster E28/39 at the Jet Age Museum at Gloucester.
Two prototypes of the E28/39 Pioneer was ordered in February 1940. The first prototype (W4041) took some short "hops" at the Gloster airfield at Hucclecote in April 1941, after which it went to Cranwell (which had longer runways and was a more secure location) and made its first proper flight in May 1941. Testing of the first prototype and the second (W4046) continued through until 1944, trying out different wing sections and engines.
Even before the first E28/39 had flown, Carter started work on an operational fighter design to make proper use of the new jet engines. He chose to use two engines mounted in nacelles in the wings, a configuration that allowed for heavy armament to be housed in the nose, and which took account of the relatively low thrust available from the early Whittle engines (although it was anticipated this would be greatly increased in future developments). Carter's experience with the earlier F9/37 twin piston-engined fighter prototypes must have helped him with the configuration. Carter presented his ideas for the new fighter in August 1940 and the Air Ministry wrote specification F9/40 around it, ordering 12 prototypes in February 1941. This went on to be the famous "Meteor" fighter (first flight March 1943), the only Allied jet to see service in WW2 (albeit very briefly). The Meteor stayed in production until the mid-1950s and saw service in the RAF until the 1960s as a night-fighter and trainer.
Gloster Meteor, the mainstay of the RAF in the 1950s.
In 1942, the first of the more powerful next-generation engines, the Halford H-1 (later to become the deHavilland Goblin), started to be tested, and other advanced designs from Whittle, Metrovick (the first British axial-flow jet engine), Rolls -Royce and GEC in America were all expected to be available soon. This made it possible to consider a single-engined jet fighter design. Initial work was done by George Carter at Gloster along with Jimmy Lloyd at Armstrong Whitworth (part of the same Hawker-Siddeley Group) who presented their initial estimates of performance to the Air Ministry who quickly seized on the possibilities of the new design and wrote specification E5/42 around the project, which was allocated the code-name "Ace". George Carter was able to delegate responsibility for the Meteor and so took control of the new project. The new design was based on using the Halford H1 engine but was to be built in such a way as to be able to accomodate any of the other high-powered jet engines expected to mature shortly. The Air Ministry was very excited about the possibilities of project "Ace" and declared it should be given priority over the Meteor if resources became stretched. Three prototypes were ordered (serial numbers NN648, NN651 and NN655).
E5/42, the first "Ace". It differed from the later E1/44 by having smaller wing-root engine intakes and a "T" tail.
A parallel project called "Rocket" was mooted by Gloster in August 1943 that envisaged replacing the single engine in the "Ace" with two smaller side-by-side Rolls-Royce B37 Derwent jets, fed by larger intakes either side of the nose.
Meanwhile, the Meteor proved to be very tractable in accepting larger engines, first the Whittle designed (but Rolls-Royce produced) Welland, then the Rolls-Royce Derwent. With the Royal Air Force going onto offensive operations the longer range and twin-engined safety of the Meteor was seen as increasingly desirable. So the order of priority was reversed, with the Meteor being given precedence and the "Ace" project sidelined, while the "Rocket" project was dropped altogether.
In 1944 deHavilland started testing their H2 engine (later renamed "Ghost"), while Rolls Royce started development of what was to become the Nene jet engine, both of which promised to have twice the thrust of the earlier jets. Both the H2 and Nene were too big to fit into the nacelles of the Meteor (the Nene was later scaled down to fit the Meteor, in which form it was known as the Derwent V). This prompted the earlier E5/42 design to be enlarged, initially to take the H2 engine, leading to specification E1/44 being issued for the new design. Four prototype airframes were ordered (serial numbers SM809, TX145, TX148 and TX150). The earlier project name of "Ace" was retained. The H2 engine required only a small air inlet, and this would have been accommodated in the wing-root, (similar to the intakes on the deHavilland Vampire). However priority was then switched to the Rolls-Royce Nene engine and the prototypes were all built with the larger intakes, on the side of the fuselage, required by the low-pressure intake of the Nene.
The Gloster E1/44 "Ace" first prototype to fly (TX145). Notice the tailplane location on the fuselage.
By 1944 it was already obvious that victory over the Axis powers was assured. Britain was broke, with its economy in a parlous state, rationing was still in force, and would continue for another decade. It was only natural that all unnecessary spending was reined back, so the E1/44 project proceeded at a slow pace. Construction of the first prototype (SM809) was only completed in 1947 and tragically the aircraft was destroyed in a traffic accident while being shipped to Boscombe Down for its first flight. The next prototype (TX145) took to the air on the 9th of March, 1948. Performance was up to expectation, with a top speed of 620 mph (998 kph) but there were major handing problems. These issues were largely fixed on the next prototype (TX148) which had the tailplane raised from the fuselage to halfway up a larger rudder with a bullet fairing (this is ironic because the original E5/42 had a high mounted "T" tail which might have avoided the issue). The new tail configuration was so successful it was adopted on production Meteors. The last airframe (TX150) was never built to full flying condition, being used for structural testing. TX145 did suffer a crash-landing late in its career (November 1950) following a flame-out of its engine, although it was quickly repaired and was back flying within 2 months.
The second prototype to fly, TX148, with the higher tailplane and bullet fairing that solved the handling issues.
Production orders for two batches of twenty E1/44 fighters (forty in all, serial numbers VP601-VP620 and VR164-VR183) were placed to production specification 23/46. This stipulated that the wingspan of production aircraft should be reduced and that they should be capable of carrying drop-tanks, bombs and rockets. An ejector seat and provision for a g-suit were also specified.
The slow pace of the project and the still precarious state of Britain's economy led to the production orders being cancelled and the two flying prototypes spent their days being used for experimental flying control and braking parachute research at Farnborough before sadly being sent for use as targets on the Shoeburyness weapons range in September 1951.
The first prototype E1/44 was apparently given the nickname the Gloster "Gormless" by Bill Waterton, one of its test pilots. With no official trial or mock combat reports available, it is hard to know if this brickbat was deserved. It had neither the super-thin wings of the Miles M.52 (or later Lockheed Starfighter) or the swept-back wings of such types as the NA F-86 Sabre and Mig-15 required for transonic performance. Neither did it have the all-flying tailplane first developed for the Miles M.52 (a design idea reportedly observed by an Americans team inspecting the Miles factory and used on the F-86 Sabre and most other tailed transonic and supersonic aircraft that followed). But its tantalising top speed of 620 mph (albeit without armament) and reportedly excellent climbing speed does seem remarkable compared with other straight-wing jets that actually saw service in the 1950s, such as the Supermarine Attacker, Grumman F9F Panther and P-80 Shooting Star. Britain neglected its defences after WW2 and then, when the Korean War started and the Cold War intensified, had to spend millions playing catch-up with its "super-priority" Hunter, Swift, Javelin and Lightning projects. In Korea, the Meteors of the Australian Air Force were badly handled by Soviet Mig-15s (powered by Soviet copies of the Rolls-Royce Nene engine) and Britain had to order Canadair Sabres until the Hunters and Swifts began to come off the production lines. It is tempting to think that the E1/44 might have provided a useful stop-gap.
Interestingly, in 1946-47 Gloster collaborated with the Nationalist Chinese government on a jet fighter design called the CXP-1001, very close in configuration to, and plainly a development of, the E1/44. It was to have had a Nene engine in a longer, fuselage with a single air intake in the nose and be armed with four 20mm cannon. The collapse of the Nationalist government in mainland China forced abandonment of the venture.
The CXP-1001 design featured larger wings with swept-back front edges, a halfway house to tailed deltas like the Javelin and Mig 21.
It should also be remembered that Gloster had actually started work on what was to become the delta-winged, twin-engined Javelin interceptor as early as 1946. Gloster evidently learnt a lot from data on delta wings recovered from Germany after the war, The Gloster P275 fighter design of 1948 had the same configuration as the Lippisch P13a. They even schemed a delta-winged development of the Meteor, complete with all-flying tail, as early as 1947 (Gloster design number P262). From 1949 onwards they had their hands full with the development of the Javelin and a planned "thin-wing" successor. The final Gloster traditional single-engined jet design showing any family resemblence to the E1/44 was a study, in 1948, for a transonic research aircraft, with sharply swept wings, powered by an Armstrong Siddeley Sapphire axial-flow engine, that was expected to reach Mach 1.2. This was hoped to be developed into a fighter in response to Air Ministry Specification F3/48, a specification that ended up producing the Hawker Hunter. Gloster did do some provisional work on VTOL designs with multiple lift-engines in 1960 (P505 and P507), some of the last design studies carried out by the company.
The Gloster transonic test design, a prone-position pilot version was also proposed..
It is sometimes said, that if Frank Whittle had got the backing he deserved, Britain could have had jet fighters in service in time for the Battle of Britain. Although I would not dismiss this as impossible, I do think it highly unlikely given the many technical obstacles that had to be overcome and the chain of events that eventually got Whittle success. Even if Britain had jet fighters in 1940, would that have been a good thing? If Germany had thought Britain had a technical edge, might they have delayed their assault on the Soviet Union until they had finished off Britain for good? A first-generation jet fighter, with the power of Whittle's first models of engine, and without the benefit of the advances in aviation knowledge accrued in the early war years (armament, armour, self-sealing fuel tanks), would have had only a slim advantage over traditional piston-engined fighters, and the disadvantages of the early jet engines' slow acceleration and high fuel use would have been very limiting. It is not impossible to imagine the Luftwaffe adopting the same tactics the Allies used against the German Me262 fighters at the War's end; hanging around their bases to catch them as they took off and landed.
Painting of the early Gloster single-engined "Weaver" project as if it had seen service in 1940/41. With a single 20mm cannon for armament, it would have to rely on "hit and run" tactics. If it had slowed down to dog-fight, or engage targets for more extended periods, its slow acceleration would have made it a sitting duck.
If the war had gone against the Allies later; dragged on until late 1945 or into 1946 (imagine the Soviet Union make a separate peace, or D-Day fails) then a fighter like the E1/44 would surely have found a welcome place in the Allied armoury. Any handling problems would have been overlooked because of its impressive 620 mph (998 kph) top speed, greater than the DH Vampire and contemporary marks of the Meteor. With emergency production, it might well have found widespread use, and alongside the Brakemine missile, held the line until the inevitable mushroom cloud over Berlin.
Gloster E1/44 "Aces" surprise a formation of Me262s.
As a fighter in the Korean War, the E1/44 would have likely have been much inferior to the Mig-15, especially in transonic performance. However, it might have faired better than the Meteor and the specifications laid out in the original production order (23/46) for the ability to carry drop-tanks, two 1,000 lb (454 Kg) bombs and up to eight rockets might have made it a formidable ground attack fighter for the time.
¹ Don't think my comments disparage Whittle's contribution at all, he deserves to be remembered as the "father of the jet engine" for his determination and perseverance; sacrificing his RAF career and health to see his brainchild through to production and use. It is worth remembering that Hans von Ohain had access to both Whittle's patent and Griffiths' research paper. But I stress that the practical use of a jet engine was waiting on the development of (or recognition of the properties of) the necessary alloys. In the case of Whittle's first Jet engine, the alloys required were "Stayblade" steel, developed for steam turbines, used on the jet turbines, although this later proved unsatisfactory and had to be replaced by G18B, an alloy developed for piston aero-engine valves. The Impeller used an aluminium alloy called RR56, developed for Rolls-Royce aero-engines by High Duty Alloys Ltd.
² Mentioned in Chapter 9 of John Gollet's "Genesis of the Jet", see sources below.
UK Jet Pioneers: An article by Tony Buttler in issue 105 (May/June 2003) of Air Enthusiast magazine.
British Secret Projects - Fighters & Bombers 1935-1950: Tony Buttler, Midland Publishing, ISBN 1 85780 179 2.
Gloster's Nene Machine: An article by Barry Jones in the September 1993 issue of Aeroplane Monthly magazine. This article is at odds with Tony Buttler's article and book on some points about the process of developing the E5/42 into the E1/44, particularly about the way serial numbers were allocated to the different prototypes.
Gloster Aircraft Since 1917: Derek N James, published by Putnam, ISBN 0 85177 807 0.
Genesis of the Jet: John Golley, published by Airlife, ISBN 1 85310 860 X.
The British Aircaft Specification File: KJ Meekcoms and EB Morgan, published by Air-Britain, ISBN 0 85130 220 3.
The Development of Gas Turbine Materials: Edited by GW Meetham, Applied Science Publishers, ISBN 13:978-94-009-8113-3.