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Aviation History
1920
1920 - 1172.PDF
cubic feet capacity for this purpose. These ships will have a speed of 80 m.p.h. with accommodation for carrying 100 passengers with an allowance of 100 lbs. of baggage per head, together with 6 or 7 tons of mails. The promoters have stated that they think this service could be operated at rates very little higher than the present cost of first-class passage on ocean ships. The Operation of Airship Services - The Traffic Possibilities The speed of the large rigid airship of today is 60 to 70 miles per hour, and with probable increased efficiency of the engines, and the adoption of larger airships for greater world routes, there -will be no difficulty in attaining a speed of at least 80 miles per hour, which would enable an average speed of 60 miles per hour to be attained on' long voyages without difficulty. The fastest ocean steamships of the world cross the Atlantic at a speed of 25 knots (28 miles per hour) ; but even this speed is exceptional, and is confined to liners of the very largest size ; 18 knots is more usual. It is only between great centres of population that there is a large enough volume of passenger traffic to justify the great size of steamship necessary to maintain a speed of even 22 knots. On such routes as from Europe to South Africa, India, or Australia, it is commercially impossible to run ships with anything approaching this speed. In the case of airships of even the largest sizes contemplated, the number of passengers and the weight of mails required to maintain a service is relatively small, and they could therefore be run over routes where an average speed of more than 18 knots (21 miles per hour) by steamship would be commercially impossible. Even on the trans-Atlantic route, between Europe and the United States, there must be on any week in the year some hundreds of persons to whom the crossing of the Atlantic in two or three days, instead of six or more, would be well worth the expenditure of say 50 per cent, more than the usual steamship fare. From investigations that have been made into the present passenger traffic, it is not considered that there would be any difficulty in obtaining the necessary support for running a weekly or bi-weekly passenger service from Europe to South Africa, India, Australia or South America. There should be no difficulty in reducing the present time taken from London to Cape Town from 18 days by steamship, to 5 days by airship ; and to India from 16 days to 4 or 5. The saving of time on these long ocean journeys would be particularly valuable for the delivery of mails. Postal services by airship will fill the gap between cable communica- tion and the present mail services. A letter wrighins; an ounce could contain some thousands of words, and if the cost of cabling only a single word were charged for its carriage by air, the airship transport company would be handsomely remunerated. Interesting statistics of the weight of letter mail despatched per week from the G.P.O. to the various ports of the British Empire were given in a valuable paper by General Sir F. H. Sykes, on " Imperial Air Routes " read before the Royal Geographical Society. The figures were :— To Egypt, 2,000 lbs. : South Africa, 4,000 lbs. ; India, 8,500 lbs. ; Australia and New Zealand, 9,500 lbs. It is therefore evident that the whole of the weekly letter mails to these places could easily be carried by a weekly airship service, and still leave room for a considerable weight of express cargo. Size of Airship Required From an examination of the great ocean routes of the world, it is found that a maximum -distance of non-stop flight between stations of 3,500 miles will allow of direct communication between any of the great traffic centres of the world, so that an airship able to carry enough fuel and oil to fly this distance at the required speed, including a suitable reserve to provide for adverse weather, and carrying an economical load of passengers, mails, etc., would be suitable for service on any of the world routes. It is considered that the most suitable economical com- mercial speed to be maintained throughout these voyages should be 60 m.p.h., which while high enough to enable an attractive saving of time, would be economical. To enable this average to be maintained the maximum speed at full power should be at least 80 m.p.h. To conform to these requirements, and to enable an economical load to be carried after allowing for the additional weight involved in fitting passenger accommodation, a rigid airship of at least four million cubic feet gas capacity will be required, which would enable suitable provision to be made for carrying about 100 passengers. This size of airship would have a length of about 800 ft., with a maximum diameter of about 100 ft. NOVEMBER II, 1920 The largest airship yet built is not much over two million cubic feet, so that considerable advance has still to be made in design and construction before an airship can be produced suitable for regular and economical passenger carrying. •" •• .".• Safety and Dependability The objection frequently put forward that airships run a great risk of destruction by fire is a natural impression caused by the frequency with which the German Zeppelins raiding London were found to be vulnerable to incendiary bullets. One might as well condemn merchant ocean ships because they could be sunk by gun fire. Only one case is known of a rigid airship being accidently destroyed by fire, and actual experience has demonstrated that if ordinary precautions are observed, the danger is negligible, and not greater than the risk of fire on board steamships at sea. The only other risk whilst in the air is that of breakdown of the engines. Rigid airships never have less than four engines, and the large passenger ships will have six, eight, or even more. A complete breakdown of all engines is most improbable, and the airship could still travel at four-fifths full speed if only half the total number of engines were in action. As previously mentioned, the German airship service operated before the War carried 17,000 passengers without a single personal injury ; this notwithstanding that on two occasions airships were wrecked on landing, but the passengers were got off without any difficulty. There is no discomfort experienced in the air corresponding to the plight of passengers on a steamship which is being rolled and pitched about by heavy seas. The conditions of the airship are rather comparable to those of a submerged submarine boat which is not affected by disturbances of the surface waters. With regard to danger of passing through electrical storms, information has been published that the " Bodensee" actually passed through an electrical discharge without other damage than the burning of the wireless aerial. There is no reason why airships should ever encounter the violent thunderstorms and cyclones which occur in various parts of the world, as these storms extend over a very small area, and there should be no difficultv whatever in the airship being able to avoid them. To be of any advantage for the carriage of mails and passengers, reliability and regularity of departure and arrival is essential. Serious delay owing to mechanical breakdowns of the engines and machinery is not likely, but, at the same time, it is probable that a special type of airship engine will require to be evolved to withstand the extremes of heat and cold which would be experienced in some parts of the world. The Influence of Weather Winds will of course, have a considerable effect on the time taken to complete a voyage. As is well-known, there are, at sea level, between fairly well defined latitudes, per- manent winds of generally constant direction, of which advantage can be taken by suitably laying out the course to be followed and varying that according to the season. Again, at the higher levels of the atmosphere, there is, in most latitudes, a constant drift which may be helpful if the winds at other levels are unfavourable. The importance to aeronautics of charting the upper air has been recognised, and it is satisfactory to know that organised efforts are being made to carry it into effect. It is now the opinion of meteorologists and experienced airship pilots that, instead of wind influences having the effect of lengthening the time for voyages, the passages over long sea routes will be shortened when routes are suitably arranged in accordance with the meteorological information regarding the prevailing winds and local conditions. On the average, about 15 to 30 m.p.h. may be added to the speed over the ground. The Development of the Mooring Tower If airships required to be taken in and out of sheds between voyages, it would be impossible, with the climatic conditions prevailing in this country, to arrive and depart independently of the wind ; because although a modern rigid airship may be in the air with perfect safety in practically any state of the weather, it is not advisable to enter or leave a shed with a wind blowing at a greater velocity than 20 m.p.h., and it would be quite impossible to adhere to a time-table for times of departure and arrival. There is no reason, however. why the actual departure or arrival of an airship at an aero- drome should in any way be delayed by wind, provided that the aerodrome is equipped with suitable mooring towers and landing gear. Following on the very successful experiments carried out 1174
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