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Aviation History
1962
1962 - 0328.PDF
330 FLIGHT International, 1 March 1962 In the Air: AVRO 748 SERIES 1 the 115kt best en route single-engined climb speed for full weight and trimmed it out with less than full rudder trim. We climbed at about 500ft/min and I was told that our ceiling in this condition was 14,000ft. Autofeather is provided so that if an engine is at 12,500 r.p.m. or more with h.p. cock open and torque falls below 501b/sq in, the propeller feathers itself. A clean stall came next. As I slowed down, longitudinal stability seemed to increase slightly. When I pulled hard back at llOkt, the stick-shaker chattered away momentarily, but there was plenty of aileron control. In steady flight at 95kt, I still had lots of aileron and the shaker began to operate again. At 88kt, with the stick coming back, but still off the end stop, there was a slight g-break, the stick came right back and we settled into a descent. Absolutely nothing else happened to mark the stall. It was as viceless as one could possibly wish, with some aileron left until the last moment. Forward stick and gentle pull-out re-established normal flight. I then set landing flap and gear down and let the speed fall off again. At 70kt the stick shaker rattled again, but there was still plenty of aileron control. We came right back to below 60kt before the g-break and stick right back announced the final stall, again without the faintest trace of wing or nose dropping. Harrison then showed me the clot's manoeuvre—pulling back harder and harder in a climbing turn at 80kt with everything down until the stick- shaker went. He continued to pull back until we just mushed away from the turn, but did not roll out of it. This is docility par excellence. Minimum measured unstick speed with 15° flap is 70-75kt and single-engined VMCA, with the same flap is 77kt. 1.2VSL in this condition is 92kt—all of which makes for a difference of only a few knots between Vi and V2 on most runways and a consequently easy task for the pilot. To check the take-off case I set the 748 climbing at full power with 15° flap and gear up at 95kt and 4,500ft. I asked Harrison to feather one when I was settled and aimed to achieve 105kt for retracting flap and 115kt for the en route climb without losing height. When the engine cut there was a big swing and I needed plenty of aileron, but the 105kt came quickly, and the 115kt, clean, followed without any loss of height and without my having to trim. The 748 was a little deficient in this area at first, but a slight wing-span extension and faster undercarriage retraction (it now takes five or six seconds) have cured it. I certainly had no difficulty in keeping the climb going, even though it was my first attempt. With the aircraft clean I then found that I could trim out one engine at full power down to 108kt. At 95kt the shaker started and I had a sizeable residual rudder load to hold, but could still keep quite straight. Finally we went into the usual docile stall at 90kt, still keeping straight on one engine. That speaks for itself. Harrison later shov.ed us a take-off at full power when the en gineer suddenly feathered one at 85kt with all three wheels still firmly on the ground. Immediately, Harrison pulled sharply up off the runway and climbed away on one at more than 5kt below V2 for the weight. He then made a circuit with 50°-banked turns and a single-engined approach for a short landing at 90kt. This was in very misty weather and with poor lighting at Woodford. After my single-engined session I made a radar controlled descent over the hills east of Woodford and a straight-in landing. The various speeds for flap and gear extension form an ideal decelerat ing and let-down sequence, which can be controlled virtually with Full flap for the Avro 748 provides a very considerable increase in wing area and the 30° tab deflection shown here. Stalling speeds clean and fully "dirty" are almost 30kt apart elevator trim alone. Successive trim adjustments as I reduced speed kept the stick forces to zero, and a final tweak or two put me into the round-out very comfortably. Elevator trim was exact and geared just right for me, so that I tended to fly quite naturally with the trimmer as much as with the stick. The touch-down called for a good pull back at the last moment. We did all these exercises at fully forward e.g., so that the.trim changes were at their strongest and longitudinal stability most pronounced. With some payload. the landing should be even smoother. Harrison showed us the gay way by talking us down the runway at full power, pulling the stick hard back at 90kt and zooming off the ground, racing round the circuit and then making a curved, fighter-type approach at 80kt He set the 748 down hard and braked to a stop in an incredibly short distance, turning round, to show us, not more than 200yd from the runway threshold! Next morning I made several visual circuits in 700ft ceiling, rain, mist and one-mile visibility. The windows gave an excellent view and even though, at the first try, I popped out of the murk after a DR circuit with the runway looking impossibly close under the nose I progressed easily from lOOkt clean at 700ft to 90kt with every thing down over the threshold. We could have landed easily, but 1 went round again to see how it felt. We made several circuits under these conditions, flying at a little over lOOkt, and I was contin uously surprised at my ability to get on the runway from odd angles with last-minute turns and changes of configuration. It was a whole lot easier to manage than something like a Cessna 310. Going back to Hatfield, I climbed straight into cloud up to about 5,000ft without the slightest trouble. Above cloud, I checked the stall for the three degrees of flap at 34,0001b gross weight. Clean, the shaker went at 105kt and the stall came at 93 kt: with 15° flap, shaker at 85kt and stall at 80kt: with approach flap and gear down, shaker at 80kt and stall at 70kt: with landing flap, shaker at 70kt and stall at 63kt. At no time was there the slightest nose-drop. At 80kt with everything down I threw the aircraft about, having to use a fair amount of rudder to co-ordinate turns. The 748 tended to continue rolling by itself after about 50° bank was applied, but nothing else indicated that by fooling about energetically at such a low speed I was really asking for trouble. By now I had flown about two hours in the 748. I had found no peculiarities except for a slight "hump" in the feel of the ailerons. At about two-thirds wheel travel there was some roughness which seemed to be partly mechanical and partly aerodynamic, but it was a manual sensation and did not affect control. I had willingly and unwillingly maltreated the aircraft and pushed it around in poor weather and good. My one feeling was that I wanted as much more time as I could get, just for the fun of it. I have not enjoyed flying a reasonably large aircraft so much since the prototype piston-engined Super Broussard, which was, of course, much lighter and lower-powered. The Convair 240 and most of the crop of American light twins gave nothing like the same sheer enjoyment and satisfaction. This does not mean that the 748 is a fighter. On instruments it just flies itself most of the time and there is plenty of attention to spare for tuning radios or other tasks. You can steam in from umpteen miles on a straight-in approach or drop down in a steep curved approach on to a short runway. The flaps are a real tour de force. Gross weight is now being cleared to 38,0001b, instead of 36,8001b, for the Series 1 aircraft. The Series 2, of course, has Dart 7s giving higher performance, and the cabin pressure has been raised to 5.51b/sq in. Airfield capability has been proved by tough trips to Aden and around the Mediterranean, where gravel and other horrid surfaces were used without difficulty. One 748 has also flown from the special mud runway at Martlesham; the films of this operation are pretty impressive. As a final effort, I made a radar-controlled circuit and ILS approach at Hatfield, partly because I needed practice, and partly because I believe that precision flying of this kind tells you more about aircraft. I misread the ILS cross-pointers twice, but I did manage to make small corrections easily with flat turns and ended up at 200ft well positioned for a landing. Control is certainly crisp enough at 90kt to make quick, small corrections easily. Someone will always be able to pick holes in an aeroplane which is apparently perfectly good, but I think—and I sincerely hope- that they would have trouble in doing so with the 748. I am a private pilot with RAuxAF experience, and the 748 is my kind of aeroplane—or one of my kinds. I think it should also suit the 10,000hr airline captain, hard though he is to please. Need one say more?
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