Cargo Capacity More Important Than High Speed
By E. C. SHEPHERD
(Sunday Times Aviation Expert) SPEED has had only a minor place in wartime air transport. Carrying big loads more slowly has become more important than carrying small loads at high speeds. That rule seems likely to be applied to post-war commercial air transport. The speeds thought likely to serve the air carrying trade best in the readjustment period lie between 250 and 300 miles an hour. These are cruising speeds. If halts for refueling are made, the average over a long journey must come well below that. An example of how fast cruising speed may suffer if it is not accompanied by range has occurred in a series of flights between Britain and India by. four Mosquito aircraft of the R.A.F. Transport Command. None occupied more than 13 hours. That means that the average effective speed over the 4600 miles between Britain and Karachi exceed ed 350 miles an hour. In fact, the flying speed was about 400 reduced to 350 by a 40-minute halt at Cairo. Speed And Range 111 Relation To Load
Even that is a marked improvement on the 200 m.p.h. which served for the Air Transport Supply of the Allied Armies and Navies during the war. The Dakota, or C-47, basically the DC-3 of pre-war days, has given magnificent service at a cruising speed of 200 miles, and has borne the brunt of the transport work in carrying petrol and ammunition, and supplying troops behind the enemy's lines, as at Arnhem and in Burma and moving troops. Its work in these respects is not yet done. R.A.F. Transport Command expects to move 10,000 men a month each way between Britain and India by autumn, chiefly by Dakotas. Mosquitoes could not replace C 47's on that duty. They can carry a great load in a concentrated form, as shown by their regular visits to Berlin with 40001b bombs, but they have no room for bulky loads. The speed of the Mospuito was worth paying for on- :the commercial run between Scotland and Stockholm, because it reduced the risk of interception by Norway-based, German fighters. In a somewhat different sense range must be paid for on certain routes. Since that between India and Australia, via Malaya and Java, has been interrupted by the Japanese, a service from Ceylon to Perth, via the Cocos Islands, has been operated with Catalina flying boats, each carrying only 8001b of mail, because the non-stop stages are as long as 3000 miles. Costly Alternatives
An alternative would be sending the mails westward from India across the Atlantic, America and the Pacific to Australia. The existing British Overseas Airways Corporation route, in association with Qantas (covering Australia), permits a saving of time. It represents speed, but is relatively costly. Mails via the Cocos Islands cost four times as much to Austi'alia as those which went via Malaya. Certain classes of mails will always entail a high cost in exchange for speed, and the re.-ent Mosquito flights doubtless fore* gather the system of express maij carrying.
Range and speed must be associated in obtaining iresults worth a special price. The prospect of such a combination in aircraft big enough to give passengers the comfort they expect is not immediate. Big aircraft for ocean services, however, are developing, and gas turbines will soon be available. This is, in principle, the jet propulsion system. Given the remarkable power which can be generated by this manipulation of expanding fastmoving gases, big aircraft can be designed with a fair assurance of high performance. Jet propulsion can be employed in its original form, or a gas turbine, driven by flowing gases, can turn ordinary air screws through gears and shafts. Jet Propulsion Factors Great but not yet economical power is likely to be available to the aircraft designer in the next few years. Speed is still hard to combine with long range. Moreover, .the jet brings the critical speeds nearer to the speed of sound at which drag or resistance increases rapidly. The tendency is, therefore, to keep the proportions of the jet-driven airliner small if it aims at speeds near 500 miles an hour. Jet propelled military aircraft of this speed already in service have even less load capacity than the Mosquito. During the next decade big aircraft are likely to work up slowly toward cruising speeds of more than 400 miles an hour, but extremely fast mail carriers, capable of taking a few passengers in comparatively poor accommodations, can be expected. They will not be cheap to operate. Charges for mails and passengers will be high, but will be paid for certain traffic. Mosquitoes now hopping between Britain and India in half a day introduce this class. They are building up a fund of experience upon which to draw when express commercial services are introduced.—Auckland Star and N.A.N.A.
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Cargo Capacity More Important Than High Speed, Auckland Star, Volume LXXVI, Issue 185, 7 August 1945
Cargo Capacity More Important Than High Speed Auckland Star, Volume LXXVI, Issue 185, 7 August 1945
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