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Aviation History
1949
1949 - 1458.PDF
222 I - I G H T The Viscount pictured in a cloud-setting worthy of its shapeliness. The slim, unobtrusive Darts belie their power potential. VISCOUNT in the air stood to be more than satisfied with the handling and performane . First of n.y own impressions was of smoothness when start- ing and running-up. The silence at this stage was unusual, but not remarkable. We started up from port to starboard, and because the ground-starter accumulators were flat the internal.batteries were used after port outer had " taken." With the least possible fuss and bother pumps were switched on, each engine selected in turn and the starter button pushed to energise the starting cycle. The prototype carries extra jet-pipe temperature gauges covering the range from 0-400 deg C, at which .point the normal dials take over. Cruising temperature is 420-450 deg C ; maxi- mum permissible, 550 deg C. From the starboard seat it is not possible to see the port airscrews, and the first indications of a start are the building-up of r.p.m. as shown by the indicators, followed by a flick from the jet-pipe temperature needles. As soon as the turbine is turning, the high-pressure fuel cock is~opened (the four fuel cocks are mounted beside the power levers on the pedestal) and the Dart picks up rapidly to about 6,000 r.p.m., its idling speed. The airscrews are at zero pitch for starting. The flying control lock incorporates a gate 'for the power controls ("throttles"); this prevents the pilot obtain- ing sufficient power for take-off if the controls are locked, but permits taxying with up to 10,000 r.p.m. While the remaining Darts were started on internal batteries, the lock was released to obtain 12,500 r.p.m. so that the generators on each power unit in turn should boost the batteries for the next to start. When all were running and the doors—two unusually large ones for a pressurized hull—closed, we could hear a distant high whine and a faint, deep, muffled rumble. Neither was- sufficiently loud to interrupt normal conversa- tion in the cockpit. In the cabin scarcely anything could be heard at all. The Darts had been run-up earlier, so without delay the nosewheel steering motor was switched on and the brakes released. Controls were locked at this stage. To me, the taxying was at first rather disturbing, for I had no experi- ence of nosewheel steering on medium or large aircraft. With the greatest of ease, and almost nonchalantly, we bowled along the apron at Wisley, round the corner of the hangar to the left, bore right up the slope past trees and a line of parked Valerias, and out onto the grass runway at what seemed like 50 m.p.h. but probably was about 20 m.p.h. The precision of steering and the power of the brakes astonished me and, in spite of the hard, fairly rough ground, there was nd discomfort, springing being excellent. Each adjustment with the steering wheel was accompanied by a squeal from the steering motor, clearly audible above all other sounds. For taxying 7,000-8,000 r.p.m. are required—rather less, perhaps, with V.V.I.P.s aboard. Turning into wind at the end of the runway, a brief cockpit check was made, 15 deg of flap lowered, and then the Darts were all opened wide against the brakes. For the first time it was possible to discern airscrew rumble clearly, but still there was no engine noise (other than the faint whine mentioned earlier) or vibration in the cockpit.
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