STILL DOUBTFUL

Evening Post, Volume CX, Issue 86, 8 October 1930, Page 11

STILL DOUBTFUL

VALUE OF AIRSHIPS

HIGH RUNNING COSTS

The first Labour* Government undertook, though it did not wholly conceive, the experiment of improving Imperial communications by means of airships. This has now reached a stage where review is possible.-. In spite of the dogmatic and contradictory utterances of prophets, whom events have already shown to bo of the minor variety, no final judgment can be passed until protracted triajs have been made and considered. If, in a world of constant technical progress, an absolute adverse judgment' can never bo- justified, it is nevertheless possible that facts may suggest a call for a halt until established difficulties have been surmounted, wrote a special correspondent in "The Times" rejently. A scheme to improve Imperial communications implies, in the first instance, the creation of a more rapid passenger and mail service between this country and Canada, South Africa, India, Australia, and New Zealand; while, at a later stage, direct intercommunication between these several parts of the Empire may become practicable. For the. first and more im-1 portant enterprise a machine is needed capable for reaching Canada of continuous flight over some 2700 land, miles; for the other Dominions the range may be shorter if supplemented by mooring masts equipped with gasmaking plant. VERY DIFFERENT. Attempting to meet such demands, 1 the Air Ministry drew up an outline specification sn which two airships, RIOO and 8101, have been designed and constructed in about six ■ years. The first was built by a contractor and the second by the State. In design (as to which there wore no restrictions save that certain factors of safety had to be fulfilled to the satisfaction of an independent body, the Airworthiness of Airships Panel) the two vessels differ materially. In structure they represent two distinct types; in the material of their manufacture the designers have favoured different alloys; and, in the propelling machinery, engines using different fuels are employed. The privately built ship shows less departure than the other from what was established practice. VOYAGE TO CANADA. Since definite information is available of EIOO, this ship better lends herself to detailed examination. How far does sho meet the requirements of a unit in a possible Imperial Airship Fleet? The following figures, which appeared in

"The Times" last November, give the still air range of tlio vessel, at different aiv speeds, when carrying a crew of -1.0, 100 passengers, and 26 tons ol petrol (the maximum in the eircumsfanccs cited): — 5000 air miles at 50 jii.p.h. 3800 air miles .at GO m.p.h. 3000 air miles; afr 70 m.p.h. Under still air conditions it is at once apparent;, the rango of the ship is adequate for any link in the Imperial chain. But, aa flat calms are rare, a mere correlation of ship performance and geographical distance provides no basis of judgment. The daily, wind direction and force over the area between termini must be the factor determining whether or not the craft can operate to a time-table. While there must be some latitude of opinion on tho relation of performance to average meteorological conditions, it will probably be generally accepted that RIOO is incapable of operating commercially between this country "imcl Canada, though on many occasions during a year, by selecting her course and the time of her start, she could, and one hopes will, make this voyage with botli speed and safety. Parenthetically it may bo remarked that on E34's now historic flight to America in 1919, the distance travelled through the air exceeded that between the termini by well over 1000 miles. Further evidence of the extraordinary difficulty of the.North Atlantic is supplied by the series of aeroplane failures on the west-bound route.' POSSIBLE. , Between England and Egypt (Ismailia), especially if a mooring mast is provided at Malta, an 8100 would appear capable of maintaining some approach to a commercial service. Of the .-journey from Egypt to India (Karachi), if an additional mooring mast is available at some intermediate point, perhaps Bagdad, the same tentative conclusion is permissible, though qualified by more hesitancy. Beyond India and south of Egypt we need not at present look. The conclusion, then is that, so far as the carrying of a- commercial load in accordance with a timetable is concerned, the two new airships, while capable of impressive demonstrations to the West, are likely to offer complete Justification of their construction only by routine services towards the' East. .There they may compete with the faster eommoreial aeroplane by reason of their ability to fly at night and their greater comfort. COMPARISONS. It is, of course, impossible to speak with. precision of the cost of airships and of airship travel until the experimental stage has been passed, but.a comparative ' estimate , can be made. Tho cost of KIOO has been officially stated at -£440,000; that is to say, £4400 per unit of passenger accommodation, an impressive amount which, when compared with a 20,000-ton, 20----knot liner, considered merely as a firstclass passenger-carrying machine,'show the following proportion: Liner, cost per unit of first-class passenger accommodation —1. Airship, cost per unit of passenger accommodation —5. This disparity, is no true indication of the respective sums on which the passenger must pay interest and depreciation, for the difference in speed of the two forms of craft must be taken into account. Since, on the Indian service, the airship will probably prove, after the initial difficulties are surmounted, two and a half times as fast as the liner, she has the potentiality of earning two and a half times the revenue in tho same period (given equal working capacity), and consequently the better basis of comparison as the relative amount on which the passenger pays interest and depreciation (taken as six times as high in an airship as in a liner, admittedly a. guess): Liner, 1; airship, 2.3. This difference, which must in some measure be reflected in the fares, will probably prove, after experience, to be subject to modification in favour of the airship. WEIGHT BASIS. The weight of KlOl, unladen, being between 95 and 100 tons, the cost per ton (if tho higher figure be taken) has been £4400, an amount which none but the most pessimistic can think impossible of material reduction. One of the world's most luxurious motor-cars costs, on a weight basis, but one-quarter of this figure, its mass-production coun-ter-part but one-twentieth, while the 20-knot liner can be built at about l-180tli of the price. « Turning'now from the capital cost of an airship considered as a passengercarrying machine, her operational expenses must bo analysed. This is difficulty for there are as yet many unknowns; but, as fuel and hydrogen are used in definite amounts, they can be contrasted with the oil consumption of tho 20-knot liner. Assuming the EIOO to fly 3000 air miles at 70 m.p.h., and to cover 2000 land miles, the consumption of petrol will be 26 tons, while that of hydrogen will amount to 856,000 cubic feet. The 20-knot liner, in covering the .same number of laud miles, will burn 594 tons of oil. Taking current prices for the two fuels, and the hydrogen at the price at which it can be manufactured at a mooring mast station, the relative cost per passenger will be: Liner, 1; airship, 5. UNSATISFACTORY. Here, speaking of things as they are, it is but just to point out that, if the airship were so successful as to warrant the capital expenditure necessary to equip the mooring mast stations with efficient rather than cheap hydrogen plants, so that the gas could be made at about the same price as is possible in England to-day, the relative figures would be changed to: Liner 1; airship, 2.3. ' ■ . The higher speed of the airship makes a further adjustment permissible. On this hypothetical 2000-mile journey, while in the liner catering expenses, for four days must bo considered, in the airship they will be halved; so, if in both cases 30s a head a day is regarded as the transport companies' costs, the relative figures become: Liner, 1; airship, 1.2. Let us now turn to some less satisfactory features. Our designers have gone a long way towards producing an efficient airship structure, but there has not been a corresponding advance in methods of propulsion. EIOO has had to be equipped-with petrol-burning aeroplane engines. ElOl has tho ideal type of prime mover in the compression ignition engine, but this is at present so heavy as to have seriously penalised the performance of an otherwise efficient vessel. It is due to tardy engine development,that one ship has less "safety than is desirable (all fires in British ships, with two exceptions, have arisen from petrol) and the other less performance than might be expected. Regrettable, too, is the lack/ of progress with regard to the material with which gasbags are made. To-day, much as was done 15 years ago, goldbeaters ' skin is fastened by a flexible adhesive to a good Egyptian cotton cloth. Process methods and the nature of the adhesive have certainly changed, but in the manufacture of the gasbags for the two airships 2,500,000 skins have to be handled repeatedly. The outer cover has made perhaps even loss advance. ATMOSPHERIC RISKS. Navigation and the effect of atmospheric electricity are questions 'which raise doubts only, to be set at rest by experience. Airship navigation, when laud, sea, sun, or stars are visible, permits of a precision not greatly inferior to that of ocean-going vessels. Even when visibility is nil, and certainly

during daylight hours, directional wireless will often allow of the same exactitude. At least two forms of atmospheric electricity have to bo considered—the brush discharge type and lightning. The former, as a result of experience, is held, not to bo a source of dauger; as to the latter, though the,; same view is taken, eonnd'euce is not so great. Two Zeppelins have been destroyed in thunderstorms, but more airships have been struck by lightning and survived. Dr. Eckcner, the most experienced of pilots, has been in airships on many occasions when they were directly struck, yet ho suffered no harm. If v ship is discharging gas when the Hash occurs, as is known to have been the case iu^ one disaster, the danger is great, for the spark may ignite the hydrogen-air mixture surrounding certain portions of the ship. If no escape of gas is taking place, a condition, corresponding with Dr. Eckcner's experience, there is nothing combustible external to the ship, and tho electrical energy passes through the metal structure of. the hull.