THE AIRWAY

Sun (Auckland), Volume III, Issue 842, 10 December 1929, Page 14

THE AIRWAY

(By

THE ROC.)

Building Huge Superplanes

IN England a giant bomber, with wheels higher than a man, takes its place in the Royal Air Force; in Germany a 400-foot-span flying-boat, capable of carrying 100 persons, has actually flown; in America there has just been tested the first Curtis Condor, a plane having a span of more than 90 feet. The building of such huge airplanes throughout the world must provide a shock for those sceptics wlio only a few

years ago said there was no future for the big plane.

Nor is this all; Fokker is working j on a big transport plane designed to carry 32 persons, and in England j Handley-Page is constructing a four- | engined 40-passenger plane, While the ! Blackburn company has under way a tri-motored 14-passenger flying-boat. When planes reach the vicinity of 100 ft span they may certainly be said to be big. There are many big planes in the world today and there is every evidence that there are going to be more and bigger planes in the future. To the layman, it may be a puzzle why big planes are aerodynamically feasible. It is a difficult mathematical problem. One immediately comes up hard against the square law and mathematicians at one school prove with seeming finality that the weight of a really large plane is such that it would take an enormous—so enormous as to be practically out of proportion —wing area to lift it. This school therefore holds that the big plane Is unsound and commercially uneconomical. DORMER’S THEORY But to overcome such argument one has only to turn to the remarks of Dr. Claudius Dornier, one of the world’s greatest authorities on the designing and construction of the super-plane, made before a meeting of the Royal Aeronautical Society in England. He emphasised the fact that all parts of an airplane are not subject to square law, that in the case of a flying-boat the increase in weight was proportional; that in the larger wing areas involved there was compensation in the high cambered thick section; that wing loading could be distributed more economically. Ilis latest flying boat, the Do.X (Do. being the contraction of his name and X being the mathematical sign for an unknown quantity), partially proves the soundness of his ra searches and experiments and may indeed, prove them conclusively by the time the tests of this huge craft have been completed. It is, of course, obvious that big planes are a necessity in the business of commercial aerial transport, for they can carry passengers, mails and other things for a relatively ,ower cost. And it certainly does seem likely, considering the progress which is being made with the big plane today, that in the future we will see sort of aero-pullmans flying regularly over vast expanses of water and land connecting various countries just as the passenger liners are doing today —great machines with cabin bunks, planes in which hot food will be served and carrying anywhere from 50 to 100 passengers. It is no idle dream. There are no insurmountable problems involved. DIESEL ENGINE But there is still another factor involved in the building of big planes, and that factor is the Diesel engine. There may come a day when planes, instead of being powered with many engines, will be powered by only one, and that one will be more reliable than any combination of even 12 could be. There is no such engine at present, but it is bound to come after the recent experiments made by the Packard people. But when the time does

arrive for the Diesel-type engine to take its place in the aeronautical world then there will still remain the problem of the airscrew. The blades of an airscrew, or a propeller, have to be of a definite length and width and set at a precise pitch to suit the engine power and the plane. The same airscrew that is used for a 500-horse-power motor cannot be ujed for a 5,000-horse-power Diesel engine. In fact, it is in con eeivable that an airscrew could be made large enough and be efficient or even practical for such a high horsepower. But it is quite conceivable that a number of airscrews might be geared to one engine and driven by it. Again, airscrews themselves are being Improved and experiments are proceeding in order that the pitch, or the angle at which the blade meets the air, may be increased or decreased from the cockpit, giving the screw a great efficiency for specific functions, such as climbing or flying level at low aud high altitudes. Thus it may be said that the Diesel-type engine and the variable airscrew may both exercise a profound influence in the design and construction of super airplanes. DIRIGIBLE HAS ADVANTAGES If airplanes are growing so large that they can carry from 40 to 100 passengers, what of the future of the rigid dirigible? The flights of the Graf Zeppelin and the RIOO make the question apposite. It is probably true, and will remain so, that passengers will be carried in greater comfort by dirigible than by airplane; but on the other hand it seems likely that this advantage will be vitiated by the fact that the airplane or flying boat oilers enough comfort and holds out an attraction in the fact that it can travel and possibly always will be able to travel faster than the airship. Big planes, as yet, are largely In their experimental stages. That is true also of giant dirigibles, but, comparatively speaking, it may be assumed that they are further along, for they have been experimented with far longer. In flying over the ocean the dirigible lias a better record than the airplane. It can be developed to carry far greater loads than at present seems possible in the case of heavier-than-air craft. The RIOO, for example, has a ballroom and Is generally fitted out in the manner of a sea liner, though on a smaller scale. Theoretically, it would be quite possible for a dirigible to carry as many as 1,000 passengers and a vast amount of freight, but practically it seems impossible. But it would be a rash prophet who would venture to express an opinion as to which of the two types of aircraft will eventually win out. For the present the dirigible has the best of the argument in long-distance flying; it can fly further than any known airplane without refuelling, and consequently it can make wide detours to avoid bad weather. Apart from speed, the dirigible is at a distinct disadvantage as regards landing and taking off. It requires a large number of men to trundle it in and out of its hangar and to moor it.