In today’s Sydney Flyer article we are delighted to welcome back author Anthony Coleiro and the most recent instalment of his X-Files series. For those of you not aware, Anthony has written 128 articles under the ‘X-Files’ series for the club magazine, with this one making it 129. What a record!
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FILE X129: GLOSTER E.28/39
I am sure we have all done this; sit aboard a kero-burner of our favourite airline ready to wing our way to our holiday destination, look out across the wing, see the engine pod(s) slung under the wing, think nothing of it and being good aviators, pull out the safety card, attentively read through it and then settle in for our flight.
There was a time of course when looking at an engine with no exposed propeller was a big deal and instead of thinking nothing of it, we would have stared in wonderment.
So how did it all begin? How did we get to a point where we have jet engines so powerful and aircraft so large that hundreds of people could fly together all in the same aircraft? Well, we need to cast our minds back some 80 years to a time when the world teetered on the edge of war, again, to a time when the monoplane was making great strides into the biplane era to find the answer.
Enter Pilot Office (PO) Frank Whittle of the RAF who was studying mechanical science at Cambridge University. His thesis and experimentation led to a patent being granted in 1932 for a turbo engine. The Air Ministry took great interest in PO Whittle’s work and ordered one of his engines in March 1938. The company he formed to produce the engine was called Power Jets. The engines he produced were tested in specially built rigs. An engine on its own however is not enough; it needs to be attached to an aircraft to see it perform in flight, strapped to a test bench is not going to cut it.
This sort of engine was nothing like anything that came before it. It could not be a case of taking an existing aircraft, swapping the engine mount, bolting on the new engine and away you go as it had been in the past. This engine was a whole new ball game and it needed a specific airframe to be bolted to.
By this time, the dark clouds of war had unleashed their fury and British aircraft manufacturers were running flat out to keep up with military demands for ever more aircraft to repel fascisms march across Europe. By chance, the Gloster Aircraft Company had some spare capacity and most importantly, the technical skill to undertake such a demanding and challenging project. On 21 January 1940, specification E.28/39 was issued to cover the design and construction of a single seat research aircraft and this was awarded to Gloster a few days later on 3 February. The specification called for an aircraft that was comfortable for its occupant, capable of 610 km/h, a climb rate of at least 4000 fpm at sea level using a 1200 lb thrust engine. Additionally, the design had to be readily adaptable to the fighter roll should that need arise.
For such a radical engine, it was thought a radical aircraft should carry it and their initial design was for a twin boom canard winged aircraft. Power Jets objected to such a radical design and Gloster was sent back to the drawing board. The design that Gloster eventually came up with was loosely based on their F.5/34 specification fighter aircraft. This aircraft ultimately lost out to the Hurricane and Spitfire so the design never really stood a chance of going into production. At least all that development work Gloster had put in to win the fighter tender did not go to waste and could be recycled into this new development. Two of these more conventional looking aircraft that they came up with were ordered to test a variety of Whittle engine types.
The design was of a low-wing monoplane with tri-cycle undercarriage with an empty weight of 1309 kg. Three different sets of wings were planned to be built for the aircraft. The aircraft was not only to test various engines but to also different wing plan forms to find the best combination.
During the time of construction, England was on the receiving end of some pretty heavy bombing and as an insurance against total loss should a bomb get lucky, construction of the various components of these aircraft was dispersed. These then came together for final assembly in April 1941. Satisfied that all was well with the construction, it was then dismantled and sent by road to Cranfield for its ground and flight tests.
The aircraft was so top secret that when it was on the ground, an around the clock guard was placed on it. At that time, guarded aircraft had the suffix of /G at the end of their registration which left no doubt in anyone’s mind who saw it that this was something significant and not to get too close.
For the taxi trials, an unairworthy engine was fitted and these tests took place on 7 April 1941 and the next day, short hops were made after which a new type of nose wheel was fitted, one with more travel and the retraction mechanism was also installed. The test pilot found that the aircraft was free of vibration and quieter than the current piston engined aircraft with simple controls and an excellent view from under its bubble canopy. It was not until 15 May of that year before the aircraft took to the air for the first time now fitted with the airworthy W.1 engine of 855lbs thrust. The acceleration was such that it was off the ground in 450-550 metres. This first flight showed that the aircraft was unstable due to the elevator being overly sensitive and it was put back down on the ground, successfully, after only being airborne for 17 minutes.
Stationed at Cranfield were several RAF units, however, the aircraft was so secret, that only those that needed to know about the aircraft knew of its existence. Something like this cannot stay secret for long and so to say that those on the airfield who did not know about this aircraft and then saw this thing for the first time taxi about and then hop along the runway were stunned at what they saw would be an understatement.
After adjustments had been made, further test flights took place and by the end of May, fifteen flights totalling about 10 hours worth of flying in all had been made and an altitude of 25,000 ft had been attained and a speed of 560 km/h.
Even though this work was top secret, it did not escape the attention of the Americans who requested the specifications of the aircraft. Being allies, the request was granted on 28 July 1941.
The aircraft was returned to the Gloster factory where the engine and the wings were swapped and on 4 February 1942 the aircraft took to the air sporting a set of high-speed wings and being now propelled by the W.1A engine of 1160 lbs of thrust. This new engine caused problems and the aircraft had to make a forced landing, thankfully it was uneventful.
The problem was resolved and it took to the air again. More flights took place and at the end of May there was an American audience looking on. Embarrassingly for Gloster, with these allied witnesses present, another problem occurred, this time with the oil pressure reading low. Another forced landing ensued but now luck had run out and the aircraft sustained damage on landing.
With repairs made, Gloster passed the aircraft on to the Royal Aircraft Establishment (RAE) for them to conduct their round of tests.
While all this testing was taking place with the first E.28/39, the second one was under construction. The second test aircraft had been fitted with the more powerful W.2B engine of 1200 lbs of thrust. It joined its sibling in the air on 1 March 1943. Up to this point the British Prime Minister Winston Churchill had not seen these aircraft fly. It was not until 16 April of that year that he had done so and it was the more powerful number 2 aircraft that he saw being put through its paces.
The first aircraft was again re-engined and fitted with the last jet engine to be tested, an even more powerful W2/500 engine of 1620 lbs thrust along with other minor modifications. This gave the aircraft a maximum speed of 750 k/ph at 10,000 feet and a service ceiling of 32,000 ft. On 24 June 1943, the aircraft reached an altitude of 42,170 ft, the first time a jet aircraft achieved an altitude exceeding 40,000 ft. With all that additional thrust, the aircraft was considered excellent for aerobatics.
A mere 7 months after it had first taken to the air, the number 2 aircraft was a smashed wreck for it was on 30 July 1943 while that aircraft was at 37,000 ft the controls froze. Left with an uncontrollable aircraft in an inverted spin, the pilot had no choice but to bale out. The first departure of a pilot from a stricken jet aircraft had successfully taken place.
Even though the aircraft specification called for it being capable of being turned into a fighter and to this end armament comprising of 4 Browning 0.303 machine guns and their fittings was made for the aircraft, however, this eventuality never happened and the armament was never fitted. After the war, the only remaining Gloster E.28/39 was donated to the Science Museum of South Kensington on 28 April 1946. Its purpose as a test bed for the wondrous new invention of the jet engine had been fulfilled and the role of practical application was left in the hands of another type.
This other type was the Gloster Meteor. So successful were those initial tests of the jet engine in E.28/39 that in May 1940, Gloster was given the go-ahead to develop their concept twin jet fighter aircraft, the F.9/40, even though testing still had a way to run. This concept became a service reality and was then renamed, Meteor.
It is interesting to note that the E.28/39 was not the first jet aircraft to fly. Actually, the Germans had achieved this feat on 27 August 1939, more than 2 years earlier! The aircraft was the Heinkel He178. It was fitted with an engine designed by Hans Joachim Pabst von Ohain. The engine was a 750 lbs thrust HeS 3b centrifugal flow jet engine and it took to the air at the Heinkel factory airfield in Rostock. You would think that such a head start would give the Germans an unrivalled advantage but that was not initially the case.
Unlike the British in which the government took an active interest in Whittle’s work and provided the funding and support to turn a theory into reality, the German government showed no such interest. The He178 was a private venture aircraft for the Heinkel company and they received no official support for the concept and it was not until 2 months later on 28 October that any government official came to see the aircraft fly and they were not really that impressed.
Of course, things did change some time later for the Germans and their eventual change of heart ultimately resulted in the twin jet Messerschmitt 262, an aircraft that stunned the allied bomber crews that first engaged with it over the skies of Germany.
There has never been anything to suggest that either side knew anything about each other’s jet developments as both had been developed under the strictest of secrecy, however, it is interesting to note that both Frank and Hans developed centrifugal flow jet engines, axial flow being a later development. These days, the only applications you mostly find for centrifugal flow engines are auxiliary Power units (APU). With two independent brilliant minds thinking the same thing, perhaps it was simply the case of the jet engine’s time had come and fate did not care who was to develop the idea.
British Prototype Aircraft
The Illustrated Encyclopedia of Aircraft
Aeroplane Monthly October 1991
The Complete Book of Fighters
William Green / Gordon Swanborough