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BRABAZON AND ON (Part 2)
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The coming days saw the usual routine activity in the Flight Research Department. I remember making an early morning visit to the Flight Operations Department to talk to a pilot, Mr. Northway, about the previous day’s flight. I had forgotten to record a vital piece of information, the engine RPM., on the final approach and he was in a position to tell me this. He was unusually off-hand with me and I put this down to his preoccupation with that morning’s forthcoming test-flight of a “hack” machine, freighter G-AIFF. Back in the offices camera magazines were being checked, stop-watches and log-sheets gathered up, and the latest copies of the flight test programme were being distributed, all this accompanied by the usual light-hearted banter. The offices fell quiet as the crew-members made their way to the airfield. Soon ‘FF’ was roaring past the huge windows of the Brabazon Hangar, its smart blue-and-silver livery shining in the morning sun, as it had done on so many previous occasions. Its reliability was unquestioned and the test programme seemed merely a matter of routine. Today was to be tragically different, however. About an hour after witnessing the take-off my boss, Austin Randell, who had been missing for some little while stumbled back into the office, tears streaming down his face. “FF is lost, they are all lost,” he mumbled, incoherently. Silence and deep gloom spread throughout the Department as the sparse facts unfolded during the morning. The submarine Truculent (later itself to become a victim of a tragedy) was leaving Portland harbour on the surface when the Commander saw an aircraft tumbling from the sky. He had the presence of mind to make a sketch of a large component which had become detached from the main part of the aircraft. He then proceeded towards the area of the huge splash which had been observed, where a single body and several pieces of floating wooden wreckage were recovered (these were in fact the pallets on which the Flight Research Instrumentation had been mounted). There were no survivors. This sudden tragic loss, involving as it did several key members of the Brabazon project, cast a deep gloom over the whole of Filton. In due course a moving memorial service was held in Bristol Cathedral. In the corner of our office was a free-standing old- fashioned coat rack and I remember to this day the old mackintosh of one of the victims, Jack Grundry, hanging there untouched for years afterwards. But life and business had to go on and it was imperative to find the cause of the accident. Theories and rumours were rife. One suggestion taken very seriously was that a propeller had shed a blade, which smashed the main hinge on the nose doors, allowing them to separate from the aircraft. Another theory was that a modification to the main cabin door, extending the height slightly and rounding it off to permit parachute jumping by airborne troops, had introduced a weakness leading to structural failure. There was little evi- dence to go on but it was known that the aircraft was carrying out a full-power single engine climb when disaster struck. (I believe that a little earlier a freighter being evaluated by the French Air Force had crashed in the Sahara in similar circumstances but cannot now be sure of this). The possibility of an explosion having been caused by shortcomings in the design of the fuel ventilation system was put forward. The fuel tanks were continuously vented by a system of approximately 1” diameter pipes in order to expel the dangerous fumes left as fuel was depleted. It was considered possible that at low speed, with an engine shut down, the flow in the system was insufficient to provide adequate ventilation, leading to an explosion, triggered possibly by static electricity or a faulty electrical component. It was decided to investigate this aspect on another aircraft. I was asked to design tiny venturi pitot heads, the barrels being less than 0.2” diameter and the pitot being made from hypodermic needles obtained from the local hospital. About a dozen of these were inserted into the tank ventilation system. Unfortunately only one suitable differential pressure gauge was available, and this was mounted on a ballast box together with an intercom pointing to a production freighter. About a dozen or so pairs of pipes would need to be connected in turn. With just the pilot and me on board we took of and flew to the south coast where good weather could often be found. We re-read the very simple Flight Programme and I suggested we could start the required single-engine climb. “No” the pilot replied, “you go down and ready yourself in the cabin and then we’ll shut down.” As I unplugged my intercom there was one last instruction: “And bloody well hurry up!” The noise in the unfurnished box-like fuselage was almost unbearable, and as the propeller slowed and finally stopped I felt the strain come onto the aircraft structure as full rudder was applied to hold the machine straight. I worked like the proverbial one-armed paper hanger, going through each sequence twice, and finally reporting “Test completed”. Before I had finished climbing the ladder to regain the flight-deck I felt the aircraft go into a shallow dive and saw the engine surge back into life. Very soon we were cruising comfortably back to Filton. The tests showed that there was a more than adequate movement of air in the venting pipes and therefore this theory as to the cause of the accident could be discounted. Later the almost certain cause of the loss of ‘FF’ was to be revealed by another tragedy. This time a production freighter on a test flight over Wales was lost with its crew of three. The wreckage pattern showed that the aircraft had descended almost vertically into the ground. The thousands of pieces were painstakingly gathered up and laid out in a hangar at Filton. It was found that the fin and rudder could not be accounted for and later these were located some distance from the main wreckage. There remained little doubt that a similar failure had caused the loss of ‘FF’. Now the ‘Bible’ which laid down the design requirements governing the strength of aircraft was known as AP970. I believe that the resulting enquiry showed that our designers had met these requirements in all respects, but the requirements themselves were then re-evaluated and found to be inadequate. Unfortunately the design of the aircraft was such that both the rudder and elevator control circuits passed through a single ‘spider’ mounted at the base of the fin. This was carried away with the fin when its retaining structure broke. The loss of the fin and rudder might well have been overcome by a skilled test pilot using differential throttles and ailerons to maintain heading, but the loss of the elevator controls was insurmountable. Fate had played its usual grim part in the ‘FF’ tragedy on that dreadful day. John Ratcliffe, the Head of the Department, had been the last to board the aircraft. Seeing what appeared to be an unusual number of faces in the dimly lit fuse- lage he made some enquiries. One lad, the son of a Senior Superintendent in a manufacturing shop, was merely going for a joy ride, and he was ordered off the aircraft. Lucky chap! Others were not so fortunate. Also on board was a small group of Aerodynamicists including the chief (Archibald) who had been called to a very urgent meeting at Farnborough and were using ‘FF’ as a convenient taxi. Shortly before the aircraft commenced its let-down to Farnborough the pilot was advised by radio that the weather over Weymouth was likely to close in very shortly. He decided to carry out the tests first and drop the Aerodynamicists off on the way home. Such is the narrow dividing line between life and death. The late Tony Wilkey |
