World War II

The Messerschmitt 262A jet fighter

The Germans were justifiably credited with a certain amount of engineering genius during the war, epitomised by their V Weapons, both of which were exceptional achievements. Because of the successes that they did have there is, I believe, a tendency to regard all of their engineering efforts as having achieved a level of excellence and, at the same time, to downplay the achievements of the British.

The Messerschmitt 262A was a fighter powered by two jet engines (there was a bomber version but the demand at the time was primarily for fighters). When it first appeared over Germany in combat on July 25 1944 it came as a shock to the pilots of the propeller driven Merlin powered Mustangs, which were used to escort the US B17 Fortresses and, up to that time had proved equal to the best that the Luftwaffe could put up and far better than the rest. The Messerscmitt 262 with its top speed of 525mph was 100mph faster than the Mustang, with a correspondingly superior rate of climb. Throughout the five years of the war up to that time the improvement in the maximum speed of fighter aircraft through numerous developments and different designs had been no more than 100mph, then suddenly this one aircraft had achieved a similar leap forward in one go. As a consequence it has been hailed as yet another manifestation of German engineering genius.

On the face of it that is how it appeared. Certainly the aircraft looked advanced, it had wings which were swept back to some extent and must have been one of the first to use this approach, which subsequently became so widely used, and the jet engines, Junkers Jumo 004's, used multi-stage axial compressors, the standard on all modern jet engines. Furthermore it looked right and, as the old engineering adage goes 'If it looks right then it is right'. In this case, however, not so.

The Mustang pilots soon discovered that the 262 had a very poor turning circle and the ability of the Mustang to turn inside the Messerschmitt gave it a significant advantage that helped to offset the disadvantage of an inferior performance and made it possible for the slower Mustang to shoot down many 262's. Turning circle was not the only weakness of the aircraft's flying characteristics, it was always dangerously close to stalling at take-off and landing and proved difficult to fly at these times. The Jumo engines were also prone to surge when the compressor stalled and required careful handling of the throttle to avoid this, furthermore they had a tendency to suffer from 'flame out' at altitude and could be difficult to restart. The operational life of the engines was also unacceptably short. The overall result was that the aircraft was something of a nightmare for its pilots and more than 200 pilots were killed in training - more than were killed flying the aircraft in action.

It is interesting to contrast the situation with regard to jet powered aircraft in the UK at that time: Sir Frank Whittle is often described as the inventor of the jet engine, which is not strictly true. The concept of the jet engine was well known from the early days of the twentieth century but producing a viable engine presented numerous practical difficulties and Frank Whittle deserves all the praise he has received for his dogged determination to overcome these difficulties despite the lack of official enthusiasm. He chose to use a centrifugal compressor rather than the axial type because it presented fewer development problems and his engine flew successfully in the Gloster E.28/39 in 1941. The E.28/39 was designed around the concept of an interceptor fighter but was seen more as a learning vehicle for the application of jet engines.

The De Havilland Engine Co built a family of jet engines based on the Whittle design, the first of which was the Goblin and similarly Rolls Royce adapted the Whittle engine to produce the Derwent. Both these engines had been developed to a reasonable stage of reliability and durability, due in part to the achievement of the material scientists in developing new alloys to withstand the constant operation at high temperatures of the turbine blades. The first fully operational jet fighter in the RAF was the Gloster Meteor powered by two Rolls Royce Derwents. The Meteor first flew operationally in the summer of 1944 and proved its value in chasing after the V1 Flying Bombs, it can be compared directly with the Messerscmitt 262. The wing aerodynamics of the Meteor were rather more conventional and the engines, which were a shade more powerful, were far far more reliable and durable, making the aircraft much more pleasant to fly. Just after the war in 1945 the Meteor established a new world speed record of 607mph, which suggests that the operational version was more than a match for the Messerschmitt. The whole approach in the UK had been towards producing a practical and durable jet fighter rather than rushing, as the Germans seem to have done, to put one into service before the development had reached a suitable stage. The de Havilland engine, which produced 50% more power than the Junkers Jumo, went into service in the de Havilland Vampire just before the end of the war. The later version of the engine, the de Havilland Ghost, went on to power the Comet, the world's first jet civil liner and, despite the tragic story of the early Comets, which was in no way attributable to the engines, established beyond doubt the viability of jet engines in civil aircraft.

Although early British engines put their faith in the simpler centrifugal compressor the axial type was not being ignored. Metropolitan-Vickers produced a prototype axial jet engine with an axial compressor. This was designed in 1938, it passed its Special Category Test in 1942 and first flew in 1943. It flew in a Meteor in November 1943. There was considerable research and development in the UK on axial compressors. All this culminated in the Armstrong Siddeley Sapphire, based on the MetroVick design, which was probably the first really practical jet engine with an axial compressor and probably the best engine of its day. So, in the field of jet aircraft at least, there is no way that German engineering was superior, far from it.

It is interesting to note also that, at that time, the USA wasn't even in the game. After the war they were keen to catch up and lured many British engineers across the pond. They wanted to purchase Armstrong Siddeley Sapphires in large numbers but, with typical British reluctance to invest, Armstrong Siddeley decided not to establish the necessary manufacturing capability and sold the design to the Americans, which enabled them to make a large leap forward.

Ron Watts