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Aviation History
1960
1960 - 0692.PDF
692 FLIGHT, 20 May 1960 Fresh from the States . . . hydraulic fluid the undercarriage can be loweredby stored compressed air fed to the jacks through separate pipes and released by a trigger locatedbeneath a removable floor panel under the pilot's seat. Rudder and tailplane trim are controlledfrom concentrically mounted winding handles located in the cabin ceiling and having individualindicators nearby. I flew first in the co-pilot's seat with TurnVigors while we made a short flight to get the feel of things. The noise and vibration level werevery low, normal conversation being audible and radio calls coming clearly from a loudspeaker justabove the 1st pilot's left ear. With the clear- vision panel open we had plenty of fresh air onthe ground, despite the heat of the day. Visibility forwards and sideways was ample fortaxying and flying and the rearmost side windows afforded a better-than-usual rearward view,although directly rearwards and upwards one was blind. The windows are high enough to afford adequate clearing visibilityfor turns, but I found that the sunblinds above the windscreen obscured some of the window area and could not be folded backout of the way without fouling the trim handles. Control on die ground was excellent, the large tyres and goodsuspension giving a smooth, comfortable ride on roughish grass. The nosewheel, which is spring-linked to the rudder pedals,allowed quite sharp turns and precise control for taxying, landing and take-off. Turns could be tightened by use of brake so thatwe turned through 180° in two-thirds the width of a 30ft-wide taxiway—with the inboard wing-tip moving backwards over theground. Asymmetric power was unnecessary for this performance. Pre-take-oflf vital actions were straightforward and printed on acard. Full power could be held on the brakes and initial accelera- tion was smooth and powerful without any detectable swing. Thenosewheel can be held down to 80 m.p.h. without any rough riding on undulating grass, but the Aztec wants to fly itself off at a littleover 70 m.p.h. Tim Vigors held it down to 80 m.p.h., lifted off and immediately feathered one engine by yanking the mixtureand pitch levers hard back with one hand. The pitch lever goes into the feather position against a friction crutch and not througha gate. The propeller stopped almost immediately and there was a barely detectable instantaneous swing before we settled into theclimb at 110 m.p.h. This was obviously no sweat at all. I then flew the Aztec around for a while and was told to cutthe port engine at 150 m.p.h. with my feet off the rudders. When I did so the aircraft twitched slightly to the left, but I needed onlyto apply about 20° starboard aileron-wheel movement to hold the cut engine and could do so without any need to trim. Restartingrequired normal pitch, rich mixture and closed throttle and some use of the starter to unf eather and get windmilling. Then mixturewas placed to idle cut-off, throttle cracked and mixture put into rich again as soon as r.p.m. reached 1,000. After that the enginecould be opened up again for immediate normal use. The aircraft was so easy to control during these operations that full attentioncould be given to reading the re-starting check-list. We then came back for a landing. Extension of flap caused a "Flight" photograph Even with five people on board and the starboard engine feathered it was easy to formate on the Super Cub used by the "Flight" photographer certain nose-up trim change, but the trimmer was effective andexact, though low-geared. We approached at 80 m.p.h. with a trickle of power and landed without any difficulty. Controlremained precise and light and hard brake could be applied immediately after touching-down. After this preliminary run-round Tim Vigors got out, I tookthe 1st pilot's seat, colleague Alastair Pugh took the right seat and two passengers remained in the back. We had flown for about30min since the tanks had been completely filled, and we were therefore at fairly near full load. With 15 minutes' dual I feltcompletely confident about flying solo. Now that we were alone we settled down to take some notesand measurements. On take-off we again noticed good under- carriage damping and excellent nosewheel behaviour on undulatinggrass. The Aztec's big tyres and large nosewheel are great assets on such a surface. The aircraft flew itself off at about 75 m.p.h. and,climbing at 110 m.p.h., we measured 1,300ft/min climb between 1,800ft and 2,500ft, not flying quite accurately—it can dol,600ft/min. At 3,000ft we set 2,400 r.p.m. and 23in intake pres- sure, 75 per cent power, and the speed built up rapidly from110 m.p.h. to about 140 m.p.h. Thereafter it increased slowly to 185 m.p.h., with a gradual nose-up trim-change caused by positivestability. Trim-changes with speed, though clearly noticeable on the wheel, were not as intrusive as they are with some aircraft.This gentle indication without brute force is a feature which makes the Aztec a pilot's aircraft rather than an operator's, andwe liked it. Next pleasant experience was a very high rate of roll with light,though not absolutely crisp, ailerons. We were pressed for time and did not wait to try stability or rate of roll, but the Aztec wasexceptionally manoeuvrable and pleasant to fly and maintained this full control right down to the lowest speeds. It could also betrimmed hands-off in all normal flight conditions. Rapid turns and reversals of turns required if anything opposite rudder—afunction of the big fin—and it was hardly worth trying to co-ordinate them.I next slowed down and held the gradually mounting stick forces; the stall-warning light shone at 80 m.p.h. Maintaininglevel flight, I noticed a considerable increase in angle of attack as the speed finally fell off to 70 m.p.h., when a sharp judderannounced the stall. The Aztec fell away in a nose-up attitude and tended to drop one wing slowly. Release of stick pressureensured recovery. Good aileron control remained right up to the stall. The undercarriage may be extended at up to 150 m.p.h., andwe found that it caused no trim change. The first part of flap produced no trim change either, but full flap brought a decidednose-up tendency which was relieved with half forward-trim travel. We then stalled at between 60 and 65 m.p.h. with a pronouncedjudder just short of the stall but retaining aileron control till the last second. The nose again stayed up and recovery was immediate.With less than full power we then found we could climb at an indicated 52 m.p.h. and full aileron control—this with four occu-pants and almost full fuel. Power had a very marked effect on stalling speed. All controls remained light and the tailplane was particularlypleasant and precise even at these low speeds. With power off I then pulled sharply back on the stick at just below 70 m.p.h.,noticing a good g margin and ample tailplane control. Pulling quickly back at a lower speed, an accelerated stall came with The Aztec's "office" is neat and roomy, with all mod. con. including autopilot. The darker radio panel in the centre contains airline- standard ADF, three VHF receivers with two VOR adapters, two VHF transmitters and marker beacon receiver. Costing £6,000, this is a standard Piper radio package. Note the deep upholstery and large door
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