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Aviation History
1982
1982 - 2705.PDF
OFFICIAL ORGAN OF THE ROYAL AERO CLUB PRIVATE FLIGHT Last flight of the Acrostar In 1970 Flight published the first account by the late Neil Williams of his now legendary forced landing in a broken Zlin. After a wing started to fold during aerobatics prac tice, he rolled and made his approach inverted to keep the wing in position, rolling up right just before touchdown. At the end of this year's Euro pean display season, Swiss (and European freestyle) aerobatic champion Eric Muller was faced with a similar situation after the eievator jammed during a power-off spin recovery in his Acrostar. This is his own ac count. "It was a Sunday character ised by a flat high-pressure system all over the Continent. I started the day with an air- show in Freiburg (south-west Germany), and then I made my way south-west to Pau in France, 521 miles distant at the foot of the Pyrenees. At 1647 I received take off clearance, climbed to 6,600ft, and at 1655 precisely I was in position over the southern part of the runway, about 1,000ft from the crowd. I started as usual with my power-off flat spin (erect), but for no particular reason I sud denly decided to recover at 2,300ft instead of my usual 1,650ft—a decision which a minute later gave me the chance to save my own life. Such spontaneous decisions are fine as long as they are on the side of safety. Intuition can, indeed, be amazing. I initiated the spin at 59 m.p.h., pulled the pitch con trol to coarse, and the mixture to idle cut-off, crossed the controls, and after three-and- a-half turns was in a stabilised flat spin with the engine off. The Pyrenees sped past from left to right every 15sec. The needle of the altimeter turned constantly, and I checked this at the halfwav mark (4,100ft) when 28sec had elapsed. Two thousand five hundred feet, 2,400, 2,300, and at that moment I simulta neously put in opposite rud der, in-spin-aileron, and up elevator—but I could not get the stick into its normal posi tion.* Something had jammed. Al though the elevator was in a roughly neutral position (I could not get it back any fur- FLIGHT International, 11 December 1982 Midler's Acrostar was a financial write-off, but is to be displayed in a French museum; there are two ex amples still flying of Swiss cham pion Arnold Wagner's design, which is of wood construction with glassfibre mainspar. Powerplant was a 220 h.p. Franklin ther), I realised that the spin was nevertheless slowing down and, for the moment, I did not have to think of jump ing out. In fact I recovered in about four rotations instead of the normal two, and managed to get the aeroplane into an almost horizontal attitude. No thoughts of diving as usual to restart the engine; first I had to find out what was wrong with the controls. I tried all possible stick and trim positions, but could get no improvement in the eleva tor response. On the contrary, it simply got worse and worse: the aircraft continued to become more unstable, and the nose went into a most unpleasant diving attitude. I told the tower that I had something wrong with my controls, and I was going to crash. I had an attitude 30° below the horizontal and increasing. The controller replied that he would send the fire engine, and I thought to myself 'Idiot, what I need is an ambulance!'—but in fact an ambulance wouldn't be any use to me, either. The altime ter indicated nearly 1,000ft, and I could see where I would probably crash. I wanted to open the canopy to jump, but the uncorrected path of the Acrostar would have gone straight into the crowd if I did. Then I took the decision to survive, and the computer in the back of my mind began to work at high speed: a CAP10 in America with a screwdriver stuck in the elevator system—crew saved by a para chute jump; a Zlin 526 crashed in Triengen, Switzerland, with a pair of pliers wedged in the elevator system—I remem ber thinking at the time that they should have inverted the aircraft to free the obstruc tion. From a calm position on the ground afterwards it is easy to work out what should have been done, but I remembered it then, and instantly gave full aileron to half-roll inverted and then pushed the stick. The nightmare was over. I had a wonderful aeroplane—a glider, in fact, and one that only worked inverted—but otherwise it was flying quite normally. I was able to turn back to the airfield, with the thought that perhaps I might not have to leave this world after all. Over the field I turned into wind. The last phase of the operation had to be carried out with great precision. My 'computer' reminded me that Neil Williams had once landed after an inverted approach, when the port wing of his Zlin Akrobat failed. The wing had started to fold up wards in erect flight, and Neil had to keep the aircraft in verted (in which position the wing stayed nicely in place) until the moment came to land. He and I had the same problem at this point, which was to turn the aircraft back upright as late as possible. If you turn too low, the wing will hit, the aircraft will yaw, and the nose will cartwheel into the ground. If you turn too high, the nose will drop and a similar thing will happen. Both very unhealthy! So I established an ap proach speed of 90 m.p.h. and waited until I was low enough (about 20-25ft), then gave full aileron and saw the ground come rushing up to meet me. I realised this was going to be an uncommonly hard landing, and the last thing I saw was a blur of grass just below me. At nine o'clock I woke up in a hospital bed; I had head injuries and four broken ver tebrae. Gingerly testing my toes and legs, I realised that they were still working—mar vellous. Everyone had been so helpful: aero-club members from Pau, my fellow-pilots from the show who came to my help, the Swiss Air-Rescue service; all served to prove just how close a family we are in aviation, especially in trouble. It was not until three weeks later that I saw a video record ing of the whole flight. My recollection was far longer than the few seconds that it lasted in reality—particularly the final moments. Investigation showed that the tube in which the Acro- star's stick is mounted had broken owing to fatigue on one side. It was displaced from its proper position and this re duced the amount of elevator deflection available to me. This story is one more in a list of incidents and mishaps that happen to aerobatic aero planes which are not equipped with starters. If I had had a starter I would have re-started the engine after rolling inverted, climbed to 3,000ft, and then made my first para chute jump." (With acknowledgements to translator Annette Carson, and the British Aerobatic Association). * Footnote: In case readers are querying this erect spin recovery technique, it should be noted that this is Eric Muller's own and unconventional method which he uses for competition recoveries, especially in this aircraft type. Briefing... Six pilots have been chosen by the Soaring Society of America to represent the USA in next year's world gliding championships, to be held at Hobbs, New Mexico. All have flown in previous inter national contests. Twice former world cham pion George Moffat will fly a modified Numbus III in the Open Class. Karl Striedieck, multiple world-record holder and national champion, is expected to compete in the 15-metre class. Dick Butler will be joined by Ray Gimmey, several times National cham pion, Tom Beltz, and Eric Mozer. Reserve members are Dick Johnson, Doug Jacobs, and David Jones. 767/
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