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April 2004, Archive Story

'TEST PILOTS' by Wolfgang Späte

A book review may seem a tame sort of Story of the Month, but read on!! Yes, I know there’s only a little bit about the Lightning, but this is such a rattling good book that I can’t see anyone who is interested in the Cold War jets grudging that. ‘Test Pilots’ is one of the best books on aviation I have ever read.

The article on 'Face-Blind versus Seat-Pan' ejection seat operation in the last issue of the Review (also SOTM 8/03) generated a great deal of interest and I thought I would look for more information on the ejection seat. I was browsing in the shop at the superb de Havilland Museum at Hatfield while representing the Lightning Association at a British Aviation Preservation Council (BAPC) meeting some time afterwards, and I bought a book entitled 'Test Pilots' by Wolfgang Späte, published by Independent Books at £19.95. This excellent book details many of the stories of the German test pilots, and reading it reminded me of the many similar stories in the books of Wg Cdr Roland Beamont. While we wait in hope for another book from our Honorary President, 'Test Pilots' will fill the gap admirably, and I thoroughly recommend it to you all.

These stories are not the purple prose of many war books, they describe in a cool and dispassionate way the thoughts and actions of very brave men (and, of course, the irrepressible Hanna Reitsch) who were often flying to the extreme limits of their machines, with the combined disadvantages of rapidly developing technologies coupled with the demands of the war. For example, Erich Klöckner was tasked with developing the 'Natter' (Adder) towards the end of 1944, when experienced combat pilots were in short supply and ways were being sought of maintaining the offensive against the Allied bombers. This aircraft was a manned, rocket-propelled single-flight projectile which could be flown by a pilot with only limited training in how to aim it at the enemy. It was to be launched vertically from a gantry and fire its nose-mounted load of 34 3-inch rockets into a bomber stream in a single salvo lasting 0.4 seconds. The pilot would then bale out, as the aircraft was simple, cheap and disposable. However, it was calculated that the average acceleration during the climb would be 2.2g, the highest projected altitude 52,000 feet, the average climb speed 420 mph and the horizontal speed while accelerating away from the fighter escort would be 620 mph! Exactly how the pilot was going to abandon the aircraft safely when his 7 minute fuel supply ran out was left to him!

Klöckner put in a less than enthusiastic assessment of the project and refused to fly it until a number of requirements had been met. He was then visited by two high-ranking SS officers, who did their best to persuade him that there was no time, the Führer needed the weapon and that nobody should shrink from his duty to defend the Fatherland in the hour of its greatest need. The word 'Ritterkreutz' (Knight's Cross) was mentioned, but when that failed there was something muttered about a pistol as they paced up and down the floor! A volunteer was eventually found and strapped in, but shortly after lift-off the Plexiglas canopy blew off and at the speeds reached by the rocket it is likely that the pilot lost consciousness almost immediately. The engine of the 'Natter' ran all the way to the ceiling altitude, then the aircraft went into a steep dive and disappeared, crashing into the Danube valley. One sincerely hopes that Messrs Beamont and Dell never came under this sort of pressure from English Electric when they were test-flying the Lightning!

However, it was obvious that this type of semi-kamikaze aeroplane was a matter of desperation towards the end of the war and that, in general, combat pilots' lives were valued very highly. With airspeeds getting higher and higher, leaving a damaged aircraft was becoming increasingly difficult and dangerous. Even if a pilot managed to overcome the aerodynamic or centrifugal forces pinning him in the cockpit, once in the slipstream, his body decelerated rapidly whilst the aircraft maintained its relative speed. By the time he reached the tail section there was already a considerable speed differential, and if he was unlucky enough to be struck by the elevator or rudder he could suffer a severe injury. Späte himself, an ace with 99 victories, twice had to abandon burning FW 190s at speeds in excess of 320 mph, and on each occasion injured himself striking part of the tail section. Späte only got out at all by using a technique in which he pushed the stick all the way forward with his foot in order to create negative 'g'. When the nose of the aircraft was pointing vertically towards the ground, he stood up, took his foot off the stick and was lifted cleanly out of the cockpit.

One of the best known cases of this problem involved the fighter ace Joachim Marseille. He had to abandon his aircraft due to an engine fire and rolled it inverted to allow a free fall out. However, in so doing he struck the tail and fell from a considerable altitude without making any attempt to open his parachute. Späte observed a similar incident in Russia, when one of his comrades had to abandon his burning Me 109 and announced his intention over the R/T. He was seen to jettison the canopy and pulled the aircraft steeply upward to absorb some of its speed in the climb, then he came out of his seat and slid along the fuselage towards the tail, passing over the elevator. He fell from an altitude of about 5000 ft without opening his parachute and finally impacted the snow-covered ground while the rest of his squadron watched helplessly from above.

The need for an ejection seat was now urgent. Such a seat had been invented by four engineers working for the Junkers company, which held the patent. However, Junkers had not developed aircraft which flew in the higher speed range and therefore needed an ejection seat, whilst Heinkel had introduced to the world the He 176, the first rocket-propelled aircraft, calculated to be capable of 530 mph, in which Erich Warsitz had made a number of very dangerous flights. A successful bale-out seemed very unlikely, even to the greatest of optimists in the Heinkel workforce, apart from the fact that the type of engine was quite likely to explode, necessitating immediate abandonment of the aircraft. In consequence, and before an ejection seat was available, plans were made to make the forward section of the fuselage containing the cockpit and pilot easily separable from the rest of the aircraft by pulling a lever. However, in trials with a wooden mock-up dropped from a He 111, there were many problems, with the chute opening too quickly and becoming tangled with the aircraft, and Warsitz, probably very fortunately, never had to make use of this method of escape.

The company then developed the He 178, the first aircraft flying with a turbojet engine, and the He 280, which flew with two jet engines several months before the Me 262 even got airborne. Having predicted a top speed for the He 280 in excess of Mach 0.8, Heinkel acquired the patent and set about developing the seat. The He 178 was not suitable for production and was not required by the Luftwaffe, but the He 280 was built for service use and an ejector seat was planned from the outset.

The first tests involved the physiology of pilots suddenly exposed to very high airspeeds. Volunteers were exposed to airspeeds of up to 300mph in a diving Ju 87 and later to much higher ram air speeds in a wind tunnel. One of the test subjects lost consciousness when he was suddenly exposed to an airstream at a speed of 450 mph. This level of aerodynamic pressure was considered to be the very limit of tolerance, and then only if the volunteer kept his eyes and mouth tightly closed. The volunteers used during these tests were medical students, and pictures of the tests revealed horrible distortions of the face as the speeds rose, similar to those seen in pilots training to withstand high 'g' combat forces in the centrifuge today.

The second series of physiological tests were to see how the body could withstand the loadings on the spine at the moment of ejection. Heinkel built a catapult track operated by compressed air to assess the effects of vertical acceleration at various speeds. However, before the track was officially accepted and scientific trials begun, four of the staff unbelievably stayed behind one night after work and decided to try it out. Two engineers, a foreman and a fitter shot themselves up the track several times with increasing pressure! The next day, three of the four complained of backache, and X-ray examination showed they had suffered small fractures to their vertebrae. It was later calculated that they had subjected themselves to a maximum of 26 g and had reached 'the objectively bearable limit'. Given that they were conducting the tests on their own and without supervision, it is likely that they did not even adopt the proper seating posture necessary to reduce injury in such tests.

Because these tests revealed that a pilot may be dazed, injured or even unconscious following ejection, an additional parachute was added to stabilise and slow the flight characteristics of the seat and to separate the pilot from the seat after five seconds. He then had to operate his own chute at a safe distance from the aircraft. Ejection seats were already being fitted to some aircraft and were used before they had been properly trialled. On 13 January, 1943, test pilot Schenk saved himself by ejecting from a He 280, and on 20 July 1943, Kapitän Pancherz was involuntarily ejected from a Ju 290, landing safely by parachute. Shortly afterwards, Jochen Eisermann piloted the trials of the seat at the flight test centre at Rechlin to the north of Berlin in a He 219 night fighter equipped as a flying test bed. The rear gunner's position immediately behind the cockpit was fitted with the seat, but the rails on which it ran were mounted tilted forward into the direction of flight. External equipment was stripped off the aircraft to reduce drag and enable it to accelerate to the required speeds.

At lower speeds, things went well. However, as the speeds increased, the seat, containing a dummy, began to exhibit alarming behaviour. During one attempt, the seat and dummy got stuck at the top of the rails. Because it then overhung the pilot's position, he would have been unable to escape had there been an emergency. On the seventh trial, the tops of the rails broke off as the seat went out and it hit the right rudder, the pilot only just managing to land the aircraft. With strengthened rails, Eisermann went up again with orders to initiate the ejection sequence at 310 mph, but was somewhat rattled by the previous flight. For some reason, he decided to overfly the drop zone at 5000 ft instead of the programmed 4000 ft, knowing very well that this would annoy the observers on the ground because it would reduce the clarity of their observations and film record.

Starting his run, Eisermann pushed the nose down to gain speed. He triggered the ejection over the release point and, once again, the seat stuck at the top of the rail, protruding well out of the fuselage above the pilot's head. Worse still, a few seconds later the dummy's parachute deployed and the lines wrapped themselves round the tail of the aircraft. It was unfortunate that the parachute was of exceptionally good German workmanship, because the canopy did not tear and the Heinkel rapidly slowed to around 125 mph, on the edge of stalling. Eisermann had no option but to stay with the aircraft, with the test seat trapped above him. He pushed the nose down again to try to gain flying speed and decided to try to collapse the canopy by hitting it with an airflow from an angle. Throttling back the left engine, he gave the right full power and applied full left rudder, yawing hard. In his rear view mirror, he saw the chute collapse and lie along the fuselage like a big white sausage. The aircraft accelerated again and the pilot was able to recover and land. Later, examining the film of the incident, he saw that he had approached the ground in a steep descent to approximately 300 ft before making the transition to level flight. The additional thousand feet he had allowed had saved his life.

The fault was eventually traced to the round piston in the propulsion unit, which was jamming when it was subjected to lateral forces at the top of the barrel. A slightly oval piston was substituted and there were no further problems. In May 1944, Wilhelm Buss became the third man to use an ejection seat when he made three successful planned ejections, and the seat was ready for production, although even these ejections were not without some drama. Before the first, the aircraft mechanic who was preparing the seat accidentally triggered the mechanism on the ground and catapulted himself out of the cockpit. Luckily for him, the compressed air system had not been fully pressurised, and he was not projected all the way to the roof of the hangar. He had a second stroke of luck when he fell back on to the wing of the aircraft and not onto the concrete floor. In the third ejection, the pilot triggered the seat from the forward position before Buss had signalled that he was ready and while he was actually holding a flare gun in his hand and looking over the side of the aircraft.

So, for the unfortunate Lightning pilots who once wondered whether to use the seat-pan handle or the face blind handle, it would be true, although not much comfort to them, to have been able to say that things could always be worse. They might have been flying thirty years earlier and in Nazi Germany! Pilots who nowadays take the instant response and automatics of their modern ejection seat almost for granted owe a massive debt to the men at Rechlin and to those in other countries who were working on the same problems and facing the same dangers.

Finally, there is a brief account of a Lightning incident in the last chapter which was written by Jean-Marie Saget, a French test pilot with Dassault. The Federal Republic of Germany intended to replace its F-84s and F-86s with a newer fighter, and a Major Werner was tasked by the Luftwaffe General Staff with assessing the possibilities. The exceedingly large Major was shoehorned into the relatively small cockpit of the Balzac 001 (the Mirage III prototype) and proceeded with his test flight. He had accelerated to about 600 kts at low level when he probably grabbed the stick too hard and induced violent Pilot Induced Oscillations in the elevator. Grabbing at the controls, he only succeeded in closing the throttle and cutting off the engine. This was actually beneficial, as the aircraft slowed down and the oscillations ceased. Luckily, the ATAR engine was simple to relight and, after receiving instructions on the R/T on which button to press, the engine was soon running again, and not a moment too soon. He made a reasonable landing, but the wing fairings had been distorted by the massive g-forces induced by the oscillations. He returned in the Spring, when they had fitted a pitch damper on the elevator just for him, and on this occasion one of the main undercarriage legs broke off on landing, producing a spectacular ground loop. Just two months away from the maiden flight of the Mirage IIIA, Dassault felt unable to include the Luftwaffe in their plans after Werner's 'inspections' of the Balzac.Major Werner then went to England and had his first flight in the P.1. Flt Lt Cockerill's report said 'During the briefing, we suggested that he should take-off without the use of reheat, because the undercarriage needed to be retracted before the aircraft reached a speed of 250 KIAS'. Here, Saget makes the point that 'When you know the English, you understand that a suggestion is exactly what they want you to do, and it was an important detail of their take-off instructions'. Cockerill went on 'However, on his very first take-off, the Major immediately advanced the throttle to reheat. The last we saw of him, he was at 20,000 ft in a perpendicular climb, still trying to retract the undercarriage'. The story circulated for some time in test-pilot circles. Later, Lockheed had to put two F-104s on the casualty list following similar 'inspections' by the Major. Buy this book. You will not grudge one penny of its purchase price.

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