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Aviation History
1955
1955 - 1509.PDF
624 FLIGHT, 14 October 1955 1 Two views of the radio rack specially designed for the T.A.A. Viscount. Accommodating British, American and Australian units in an integrated system, the rack is assembled and completely wired in the radio shop with all cables terminated and then coiled. The rack is positioned in the aircraft and secured, and cables are laid into quick-entry ducts and clipped into position; and aerials and power are then connected. Shown in the right-hand view are the centralized radio junction box, with circuit-breaker panel on left and ancil- lary components panel on right. TURBOPROPS OVER AUSTRALIA . . . electrical noise and it has enabled modifications to be incorporatedeasily and rapidly on overnight services. It was found, for example, that tarmac handling could be speeded up and simplifiedby the provision of intercommunication between the despatch engineer and the captain, and, with the system in use, it wasfitted in an aircraft in about one hour. The Australian ground-air communications network is nowsuch that V.H.F. is the general rule. The 1,800 miles between Melbourne and Perth can be flown with V.HJ*. communicationsexclusively at 25,000ft, while at 20,000ft there is only one gap of 100 miles where the pilots have to resort to H.F. communications. One item of radio equipment which has really paid dividendsin the Viscount is the Australian-made 200 Mc/s double-pulse distance-measuring equipment, now classified as a mandatoryrequirement in all civil aircraft in Australia. It is essential with the Viscount that the descent is started accurately at a specifieddistance, and it is generally planned to descend on to the runway wherever possible widiout using any appreciable power so as toreduce the fuel flow. In achieving diis plan, D.M.E. has proved to be of incalculable benefit. Descent is carried out with verylittle torque and at a comfortable airspeed. T.A.A. pilots have a rule-of-thumb method of using D.M.E.to calculate their descent plan, in that height in thousands of feet multiplied by three gives them the distance out in miles at whichto start their descent; height is then constantly checked against distance at regular intervals during the descent. The D.M.E.has an accuracy of better than ± 2 per cent. Experiments are being carried out with a cruise-climb procedurewhereby the pilot retains a constant angle of attack during climb, changing indicated air speed at five-knot intervals with change ofaircraft weight (as shown by die fuel-flow meters). Altitude is ignored and die Viscount is allowed to find its own altitude. . * Performance Bonus The last two aircraft delivered to T.A.A. were fitted with slippertanks, which increased the fuel capacity by 290 gallons to a total of 2,240. When diese aircraft entered service on the Melbourne-Perth route, it soon became obvious that their performance figures varied greatly from the figures quoted by Vickers in dieir perform-ance publication. Despite the slipper tanks, the Viscount was capable of achieving higher cruising altitudes than Vickers hadanticipated in the relatively high temperatures encountered in Australia—and at high altitudes greater cruising speeds wereobtainable. To produce the detailed flight-planning information which thecrews require to make accurate estimates of fuel uplift and time- of-flight over various routes for any weight, altitude and tempera-ture under any wind conditions, T.A.A.'s technical department have been carrying out a series of measurements of Viscountperformance over die range of Australian operating conditions. This work is still in progress but in die meantime crews are usinginterim planning tables based on early Vickers data. Enough information is, however, now available from this T.A.A. perform-ance study to show the trend of cruise performance at 13,600 r.p.m. The engines are using more fuel than anticipated at a giventemperature, but fortunately they are also producing a greater torque. At high altitudes die slipper-tanked Viscount 720 isestimated to be about 15 kt faster than expected from early Vickers data, and at low altitudes the E.A.S. is somewhat less than Vickersforecast. The net result is quite beneficial, and has been some- thing of a pleasant surprise to T.A.A. The introduction of a British airliner to a fleet where onlyAmerican aircraft had previously been used has, naturally, not been without its troubles. It is felt that die two main problemscan be listed as: (a) The difficulty in keeping a supply line from the U.K. to the Antipodes moving effectively under such draw-backs as dock strikes, transport strikes, and a 12,500-mile delivery pipeline; and (b) die attitude of a few accessory manufacturerswho eidier considered that all their units should be returned to the parent factory for repair regardless of dieir geographical locationand the facilities of die customer's workshops, or else provided insufficient maintenance data and spare parts lists to enable theirunits to be adequately serviced by die customer. While the situation (a) is one which will vary from day to day,and can be reasonably safeguarded, condition (b) is one which die members of die British industry should take particular pains toimprove in order to safeguard their reputations overseas. A com- parison between a maintenance manual and parts lists publishedby an average American ancillaries manufacturer, as against the equivalent publications of a British manufacturer, will illustratethis point. One need scarcely add, in view of published figures, that thefive Viscounts have now settled down well in Trans-Australia Airlines, and that their advent has certainly been a highlight inAustralian civil aviation. During die year 1954-55, for six mondis of which die Viscountswere in operation, Trans-Australia Airlines' full fleet flew 322,099,670 passenger-miles widi an average load factor of 70.0per cent, an increase of 4.2 per cent over the previous year's operations. As die average load factor of die Viscounts for diissix months period was 85 per cent, it will be seen that they must be credited widi a marked effect on die overall picture. T.A.A. have anodier type 720 Viscount on order for deliveryin December to replace dieir first aircraft VH-TVA, which was lost in a training accident soon after delivery, and they have alsoordered five additional Type 756 Viscounts, diree of which are scheduled for delivery during die first half of 1956, and two earlyin 1957. The V.756s will be of similar appearance and size to die V.720,but will be fitted with Dart 510s and Rotol parallel-plan-form airscrews. Seating will still be for 44 passengers, but twin toiletswill be provided in the rear of die cabin instead of one, as at present. Cockpit layout will be changed somewhat as a resultof operating experience, and engine auto-synchronization and the Smidis SEP-2 autopilot will be fitted. These aircraft, like the last two V.720s delivered, will be fittedwith provision for slipper tanks, which have given the V.720 a conservative range of 1,550 n.m. in still air with a 400-gal reserve. Engineering to improve die Viscount 720, such as flight deckventilation, additional forward cabin soundproofing, improved pilot's vision, etc., is constandy in progress. All of us in T.A.A.feel diat when three V.756s join die six V.720s on the Australian routes next year, the company will have well and truly launchedthe propeller-turbine era in Australian air transport, with its accompanying benefits to die passengers and to die economichealdi of die airline industry.
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