Hitler's Jet Plane (4 page)

The major change to the airframe was now no longer possible on the grounds of time alone. The financial loss to Messerschmitt AG was estimated at around RM 40 million (a labourer’s annual wage at the time was about RM 1,500). Enormous sums had to be paid to the suppliers of materials, fitments, equipment and instruments. Scarce raw materials from partially completed aircraft were piled into great mountains of scrap in large warehouses. The loss in aircraft production and valued members of the workforce completed the blow for the Augsburg works, which in peacetime would have been bankrupted. Messerschmitt was relieved of his position as company head and retained only as a technical director.

Naturally, no effort was spared to convert and modify the design into a safer, better aircraft. The result was the Me 410 ‘fast bomber’ with a top speed of 590 kph which could carry a one-tonne payload and was gunned-up as a destroyer aircraft. There was a corresponding reconnaisance version. It was a decent aeroplane certainly, but not one which lived up to the high expectations one had of a Messerschmitt.

Udet committed suicide four months after the Augsburg visit. The grandiose fighter ace of the Great War, the unsurpassable pilot and daredevil aerobatic flier, the man who loved life, it was never within his capabilities to adjust to the hard realities of a high office of state. To blame Udet alone for all the inadequacies, errors of judgement and neglect is unjust. In the Luftwaffe pecking order Udet was below Goering and Milch, and he was the only one who really cared nothing for career and power. He had lived his life as an aviator. The future held only humiliation for him and the loss of his freedom. Therefore he chose to go.

Willy Messerschmitt had no intention of abandoning work on the Me 262 in the wake of Milch’s visit. A few days afterwards he had discussed his situation with Senior Engineer Meyer, head of the monitoring office, and found him sympathetic. All held the view that nothing useful would be served by bringing work on the aircraft to an abrupt halt, for it was making no demands on production capacity nor consuming large quantities of materials. Therefore Meyer agreed to turn a blind eye to no more than two dozen engineers continuing to work on the project.

It was the winter of 1941 before a pair of 003-TL turbines arrived from BMW Berlin-Schönefeld. Once fitted, the ground rolling trials lasted into March 1942. Fritz Wendel familiarised himself with the construction, operation and maintenance of the new engines both during these running trials and also with Junkers at Dessau and BMW. To safeguard the test pilot against all eventualities in the air the central piston engine with spinner would be retained. This motor required its own fuel tank and the back-up system made the aircraft very heavy but it was decided not to take the chance that the new jet engines would provide a trouble-free performance first time out.

In high spirits on 25 March 1942 Wendel carefully pushed the two throttle levers to full power, released the brakes and let the Me 262 roll forward. During the first minute all went well. It was immediately obvious that the aircraft needed more than a 1,000-yard runway but just short of the airfield fence the machine rose quickly to 150 feet. As Wendel was retracting the undercarriage the left jet stopped, quickly followed by the other. A jet aircraft configuration cannot glide and without the piston engine in the nose the aircraft would have fallen to the ground with little hope of survival for the pilot. As it was, Wendel was able to maintain his low height, make a careful circuit and land safely. An engine survey revealed that the compressor blades of both turbines had failed. They were fractured, torn, bent, wrenched from their sockets, had glowed with heat. It was a failure of materials. Materials which had been expected to be, but were not, adequate for the task they were called upon to do. This was not something merely irremediable overnight; there were no basics to go back to, for no prior flight data existed. The test rig in the BMW factory and running trials at Augsburg had proceeded satisfactorily and therefore the failure of both turbines simultaneously was apparently inexplicable. What was not understood at the time was the extent to which scientific research and practical experimentation into materials was necessary to make jet engines as safe as they are for modern commercial passenger-carrying aviation today.

BMW’s engineers retired to Berlin-Schönefeld with their ruined turbines and it would be a long time until they were heard from again. Whether the project would have survived had not the Jumo 004A powerplant reached the completion stage at Junkers Motorenwerke is a moot point. As with BMW, Junkers had also received a contract from the Reich Air Ministry to develop a jet engine. Leading a team of specialist engineers, Dr Herbert Wagner, Head of Development at Junkers, had embarked on the task in 1935. Four years later work began building the 004A.

Von Ohain, with his jet engine for the He 178, and the British designer, Whittle, used radial compressors; Junkers and BMW preferred an axial construction with a smaller frontal surface more suitable for higher air speeds. Dr Anselm Franz, who was responsible for jet-engine development at Junkers at the time and after the war was appointed Vice-President of the Avro – Lycoming Division, Stratford (USA), wrote in 1967:

Taken as a whole, the 004 jet bears great similarity to the modern jet engine. It consisted of an eight-stage axial flow compressor, six single combustion chambers, a single-stage axial turbine which drove the compressor and a jet with an adjustable needle which was built from the beginning for the later addition of an after-burner. A special regulator had been developed which at higher revolutions kept the selected revolutions and the corresponding gas temperature constant automatically. This regulator was mounted together with other equipment on the upper side of the compressor housing. The starter motor was located in the compressor intake hub. The contract specified a thrust of 600 kg at full throttle, but a large reserve was expected. The design of the Jumo 004A was completed in the spring of 1940 and the engine first ran on the test-stand on 11 October 1940. Full revolutions were achieved in December that year and it was run at 430 kg thrust in January 1941. Cracks in the compressor blades caused by vibration then brought the test-stand development to a halt. The designed thrust of 600 kg was reached in August 1941 following modifications to turbine wheel construction. In December the same year the engine was run for ten hours, 1,000 kg thrust being obtained. Apart from the vibration problem mentioned earlier, few other basic flaws came to light in the development and testing of the 004A. After these extremely promising results the Reich Air Ministry contracted for eighty units of 004A for further development and operational testing.

Procuring the high-value and rare materials to progress the 004 development presented special difficulties. Tricks-of-the-trade and improvised solutions had to be employed in order to proceed at all. Dr Franz continues:

The 004A engine was an experimental rig. For that reason and because of the scarcity of certain valuable materials in Germany at the time – heat resistant materials such as nickel, molybdenum and cobalt were simply not available – it was unsuitable for mass production. To mass-produce the Jumo 004B required a far-reaching, radical reappraisal of the situation. As an example I would mention that sheet-plated areas such as the combustion chambers and thrust jet were adapted to take the normal steel plate flw 1010, the surfaces being protected against rust by a layer of aluminium. Special air-cooling measures were necessary to keep the temperature of the plating within acceptable limits. The production-line 004B had a thrust at take-off of 910 kg. On tests beginning in the summer of 1943, fractures were found in the turbine blades. This was due to a resonance between the vibration count of the blades and the vibrations occurring in the six combustion chambers at maximum revolutions. To save time we often resorted to unusual methods. In this particular case I recall well the professional musician with the perfect ear brought in expressly to determine the individual vibration count of each turbine wheel blade by use of a tuning fork. This method was successful. After a short, rather tense period, the difficulties were overcome substantially by a slight increase in the vibration count of the blades and a corresponding reduction of the maximum revolutions count from 9,000 to 8,700 revs per minute . . .

Dr Franz’s report highlights the Achilles’ heel of the jet engine in the development stages: the material of which the turbine wheel blades were manufactured. They were required to withstand a very high degree of heat and revolved at enormous velocity. It remained an awkward snag in jet engine development years after the war. One cannot praise highly enough the success of the Junkers Motorenwerke people in solving such problems under the adverse circumstances of the time. Although there were occasional breakdowns, they occurred relatively seldom in the operational career of the Me 262.

It is fair to assume that the problem defeated BMW’s engineers. The failure of the two jet engines on the first test flight was in no way attributable to technical inadequacy on their part but rather to the absence of technical experience in a completely new field and the general shortage of materials in Hitler’s Germany.

Four months had passed since the unsuccessful maiden flight of the V1 with a pair of inadequate BMW turbines. Meanwhile work had proceeded apace on prototypes V2 and V3 and these two aircraft had each received two Jumo 004A turbines. Despite the proven wisdom of the belt-and-braces approach, it had been decided to run the risk of pure jet flight. V1 had been relieved of its piston engine and none had ever been installed in the other two prototypes.

For security reasons but also because the runway was a hundred yards longer than at Augsburg, the V3 maiden flight took place at Leipheim. This was the aerodrome where the Messerschmitt
Giganten
, the Me 321 and 323, were flown and tested and security was very tight there.

Following the successful completion of the usual tests and rolling trials, 18 July 1942 was set for the first Me 262 jet flight.

Using results obtained from take-offs with the piston-engined V1, calculations had shown that with an all-up weight of five tonnes, V3 would leave the ground at a speed of 180 kph. It was known from runway trials using the jet powerplant that this speed was reached at a point about 800 yards from where the brakes were released. It left a reserve of only 300 yards from the end of the runway. This was not much, and – worse – on the rolling trials at between 170 and 180 kph, the V3 had so far shown no inclination to want to lift off!

All previous flights had been made with a propeller running. After hurtling down the runway on more occasions than he cared to count, Fritz Wendel had now determined the cause of the problem. Since there was no air stream from a spinner, the attitude of the upper wing was influenced by the strong slipstream behind it. This reduced the effectiveness of the flaps to the extent that when the aircraft was approaching its take-off speed, it had still not assumed the designed horizontal attitude. A nose wheel would solve the problem but it was out of the question to suspend the test programme while the two jet-engined prototypes were fitted with a retractable nose wheel, or a modified V4 built.

The reportedly unfavourable demeanour of the competent Reich Air Ministry officials towards what was beginning to look like a new type might perhaps have brought the whole project to an untimely conclusion. The rejection of the two perfectly viable Heinkel aircraft, including the He 178 jet, in August 1939 had not been forgotten and the scarcity of certain valuable materials was assuming worrying proportions. In short, there were plausible reasons for the gentlemen in Berlin to postpone the whole enterprise until after Final Victory had been achieved, an event of which all were still confident at the time. In the struggle between technology and politics lay the root of tragedy, as one would later discover.

Compared with great concerns of State in Berlin, the worries which preoccupied Leipheim were minor matters indeed, except to Wendel, who was now facing a challenge involving the question of his personal survival. During the deliberations as to how the Me 262 V3 tailplane could be elevated enough for take-off, the apparently absurd suggestion was put forward that at 180 kph and only 300 metres from the end of the runway, Wendel should step on the footbrake. If he got the pressure just right, it would get the tail up, at the same time raising the tail control surfaces out of the slipstream. The idea was logical and it would work, that was obvious. But it meant dicing with death.

If the pilot braked too hard at that speed, he risked somersaulting the aircraft. Even without full tanks his chances of survival would be slender. If on the other hand he applied the brakes too gently, the tailplane would not rise sufficiently and the ailerons would not escape the evil influence of the slipstream. Whatever he did next, he was bound to overshoot the runway end. Suddenly ploughing through a cornfield at 120 knots or so would require luck for survival. Those were the two alternatives which went alongside success; the odds were two-to-one on for disaster, and when the possibility of failure of one or both engines (as had happened previously) was thrown in for good measure, he reckoned his chances of survival as no better than 25 per cent. It was with this outcome in mind that at 08:40 hrs on 18 July 1942 he pushed the two throttle levers of V3 to maximum thrust.

300 yards from the runway end the pilot stabbed firmly but briefly at the footbrake. The nose of the jet dipped to the horizontal, the ailerons came into the airstream and the aircraft obeyed the stick. Just beyond the 900-yard mark the Me 262 rose into the air. The sharp whine of the Junkers jets remained constant and in his joy at the successful take-off, Wendel dismissed from his mind all the earlier difficulties. Instead of the robust, noisy piston engine squatting in the fuselage ahead of him to which he had become so accustomed, he heard only a soft rustling like a refreshing breeze. The control surfaces were slick to respond and the 5-tonne machine cruised like a bird carried on a thermal.