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Aviation History
1952
1952 - 2095.PDF
i August 1952 127 The terrain around Rlantyre Airport, Nyasaland, is not particularly inviting for pilots. made for it to fly over two of the routes operated by Central African Airways in order that that company might be better able to assess the aircraft. On return to Nairobi on November 14th, after a short demon stration trip to Entebbe, trials were resumed and within a few days word was received that the Shell company had been able to deliver the methanol at Mombasa. Accordingly the Viscount was flown to Mombasa without delay and, as a result of some very energetic and efficient work by all concerned, 200 gallons were available on the airfield at 1 p.m. on November 20th, although the ship had only arrived in the river at 8.30 that morning. When water/methanol is being used in the Darts (to restore power to the I.C.A.N. equivalent of 1,400 s.h.p. at sea level) the supply to the engine is automatically controlled, the pilot's only satisfactory for all normal purposes. The Smiths autopilot was another piece of equipment which received special attention; it functioned satisfactorily on all occasions, including periods of flight in rough trcpical air. Serviceability as a whole was remarkably good, and one of the only troubles experienced was the failure of No. 1 generator at Nairobi. However, it seems certain that there was good reason to expect such an occurrence, for most of the engine starting was done with the aid of internal accumulators. Starting entails a drain of some 1,000 to 1,200 amp, and an average of 92 starts were made with each Dart engine. It is estimated that, in the case of Nos. 3 and 4 Darts, 70 per cent of the starts were made on internal accumulators. In this connection it may be mentioned that on occasions the starts were somewhat slow, but, even so, the limiting ^ _-__«.BHMHjMMMBHBMMKg action being to operate the master switch in preparation. The unit governing rate of flow depends upon the balance between torque- meter and a spring. With the power lever in maximum r.p.m. position and the master switch on, water/methanol is injected into the Darts whether it be for take-off or, for example, in the event of a baulked landing. Provision is made in the Viscount for suffi cient water methanol for one take-off, plus two baulked landings or overshoots, at maximum temperature conditions (I.C.A.N.+ 30 deg). Some figures recorded during baulked landing climb trids and for take-off with water/methanol injection are as follows : Baulked-landing Climb.—47,500 lb, four engines operating, flaps at 40 deg, chassis down, 100 kt I.A.S. At S.L.—1,180 ftmin at air temperature of 35 deg C. At io,oooft—500 ft/min at air temperature of 13 deg C. Preliminary-approach Climb.—47,500 lb, three engines operating, flap 30 deg, chassis down, 100 kt I.A.S. At S.L.—580 ft/mm at air temperature of 37 deg C. At 10,000ft—110 ft/min at air temperature of 10 deg C. .... T.O. Performance.—Distance to 50ft with cngme cut at critical speed of86kt, 1,470 yd. Height 1,250ft. Air temperature 38 deg C (100 deg F). An examination of reports on what may be called incidental tests reveals that special equipment and instruments functioned satisfactorily. The ground ventilation system was found to be adequate for all normal airline conditions, but this is not to say that use of a ground conditioning truck is not better in the tropics. The pressure system gave no trouble, although one routine ground check at Wadi Seidna revealed that a filter was becoming blocked with sand; a remedy in detail design has since been found. In spite of warnings to tarmac hands and great care by crew, the pressure seals around the door frames were found to surfer damage from steps, so the seal has been transferred from the frame to the door itself. A special heat-resistant rubber is used. A careful note was kept of the behaviour of the fuel-contents gauges and they were checked against the actual contents of the tanks As a result, it was considered that the gauges are quite (Above) The Standard Telephones S.T.R. 18 HF equipment, which gave excellent results during the trials. (Left) Large crowds cheered the arrival of the Viscount at Entebbe, Uganda's fine modern airport. The aircraft stayed to give a short but impressive demonstration flight. jet-pipe temperature was never exceeded. Except for routine inspections and the attention required to this one generator, the cowlings of the four engines remained untouched for the 104! hr of the trials. Perhaps the most remarkable figure quoted in the results is the total oil consumption, for the four Rolls-Royce turboprops, of 8 A gallons. This is approximately two gallons per engine and gear box per 100 hr, and, as provision is made in each engine for five gallons of oil, the whole trip could have been made safely without topping up. This experience confirms results obtained with the prototype during its European tours. In the same period as the 8i gallons of oil were used, some 27,000 gallons of kerosine were burned. Radio—While in Africa the Viscount carried a new type of H.F. R/T, the Standard Telephones STR.18, from which some excellent results were obtained. This set utilized the normal type of wire aerial, running in this case from above the wireless operator to the tail fin. During a test flight from Nairobi, Salisbury was worked on 11,360 k/c at 25,000ft, the distance being 1,200 statute miles. On November 26th, from a position 170 miles N.W. of Wadi Haifa, at an altitude of 20,000ft, and again on 11,360 k/c, London was worked, strength 2, and clear each way, and Malta strength 3 and clear. The distances involved were, respectively, 2,580 miles and 1,280 miles, and the time was 8 a.m. In the afternoon of the same day, when flying 75 miles north of Benghazi, Karachi, 3,100 miles away, was worked, strength 3, clear. During the return flight to England, on November 29th, Malta and London were worked throughout the flight on the Malta-Nice leg, and, on the descent into Nice, London and Shannon were worked every 5,000ft at strength 5 for each station; and even on the ground at Nice contact was maintained with London and Shannon at strength 5 each way. The V.H.F. equipment on the Viscount was the 70-channel STR.12A, which uses a standard whip aerial. This set also gave
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