"Air Bicycles" German Experiments With Gliders

Hawke's Bay Herald-Tribune, Issue 27, 16 February 1937, Page 15

"Air Bicycles" German Experiments With Gliders

"rjOMMAND of the air" to post-war Germany ls what "mlstress of the seas" has been to Britaln slnce the days Of Znizkbeth. In a word — "pafety." .What Germany has achieved ln airmanshlp slnpe 1919 has provided the world with sensatlons Ih plenty. But What we know pf her attalnments ls far from being all. When a Gefman speaks of "coinmand pf the air" he does not niean that Germany b to be made ntunerlcally superior in air forCe to all other countries. What he ls really thlnking of ls that German airmen Should be as completely at home in the air as birds. -

m m w THIS ls most atriklngly lllustrated by another record performance ln human , flight attained at Fulsbuttei, near Hamburg. dii November 21, when a young pilot, Helnrich Hofmann, of Oflenbach, in a machine constructed by two German engineers, Haessler and Villinger, flew 427 metres. ln an "alr-bicycle," driven by muspular power, beating his own previoiis record of 390 metres established last year. • '• * rjOMMERCIALLY, lt has been asserted, one-man power muscular flight, even if it were successful, would be of no value. Watt's discovery of the expansive pbwer of steam might also have met with the same oriticlsm at the time. What Hofmann's performance ls w'orth as a cbntribullon to the future of flying may be gauged by what has been learned of aerodynamlcs through the sport of glidlng. Who could have foreseen that the flrst flight of the Wright brothers on December 17, 1903 — a distance of 35 rnetres in 12 seconds — would have led to siich a future? But, short'as it was, lt, proved that flight ln heavier-than-air machlnes was a possibillty. To-day, giveti unlimited power, almost any desired result as regards speed, altitude, or distance can be reached. DDT what has been engaging the thought of German scientists, engineers and airmen for several years ls the fact that birds fly lncredibie dlstances, remaining ln the air for days, with apparently no eSort at all. German experlmenters are trying to discover how this is done. That was why, ln July, 1933, the Frankfurt Folytechnlc Society offered a prlfee of 500 xeichmarks to the first person to fly a distance of 500 metres, between two flxed points and making two stipulated turns, izslng no other, energy of propulsion than human muscles, supplempnted by such ppwer as could. be stored by, a compressed air hand puinp, or ,by fhick rUbber bknds twisted tlghtly by the pilot himself, within not more than half an hour of the start. • • • YHIS ofifer set many people experimentIng, but the only ones who have achieved any conspicuous success are the two englneprs, Haessler and Villinger, : employed ln the glider-maklng departinent of the famous Junkers works at i Dessau. Experimentlng in human flight i became their hobby. The limited amount 1 of time at their disposal explains why ] progress was not more rapid. All their c work has been based on what they know ' i

of glldlng, learned at (ha Junkers works. Self-startlng gliders can now be constructed with ayxlliary motors as small as 'from li to 3 horse-po'wer. But this seems to be the minimum useful motor strength. If a man could exert as much muscle power long enough , to raise a glider lnto the region. where thermal air cyrrents flow the. problem, would be solved. But researches made by the famous athletics physician Professor Brustmann show that while fast 100-metre runners can exert as much as 7 h.p. for 10 seconds, and rowers ln training 2 to 2 h h.p. for about 10 minutes, the average human being cannot continue for any length of tlme at more than i h.p, ln exceptional cases 4-5ths h.p. So the solution would depend on the possibillty of making a glider that could be raised lnto the upper air with this amount of energy. At first sight it would seem extremely unlikely that this could ever be accomplished. The lightest machine ever made j weighs 50 kilogrammes (a kllogram ls about 2.205IJj.) and the average pilot 75 kilogrammes. So a weight of 2751b would have to be lifted about 250 feet. The heavlest flying creatures found, in Nature weigh scarcely one-sixth toone-eighth of that. • • • * TN glldlng no power ls exprted. at all once the pilot has reached the region where thermic air currents are in motlon. Gliding depends on these currents. In still air the guider would fall like a stone. The pilot keeps afloat by moving from one up-current to another. Human flight will be possible only when the pilot, using muscular power, can get high enough to make use of these currents. After that, it is gliding, pure and simple. To judge from Hofmann's Iatest performance, Haessler and Villinger are likely to wln the Frankfurt Pqlytechnic Society 's prize at no very distant date. It is clear that distance is not what really matters in human flight, but altitude. Bird-flight alone can bring the solution Hofmann's present machine to all intents and purposes is just a special kind oi glider. It weighs 50 kilogrammes, has a breadth from one wing-tip to the other of 13-i metres and a length from nose to tail of 5£ metres. • * • • rT,HE wooden propeller, attached Just in front of the pilot's pit, measures 3 metre (39.37 inches) from tip to tlp, is worked entlrely by pedals, just as if the pilot was cycling, attaining as many ar 500-600 revolutions a minute. The pilot Steers with his hands, the tail being flxed and the altitude regulated by movable flns on the wings. Experiment shows that all the power that can be stored in twisted rubber bands ls exhausted by the time the machine has gone 20 metres. It is from the muscles of the legs that the real motive power must come. In this type of machine the wings are figid. Birds overcome gravity by flapping their wings. A glider can do nothing in a cairn. But birds, as it were, generatc with their wings the wind that enables ihem to fly! Hence experts agree that the problem of muscular flight can be solved jnly with a machine with movable wings. iUong these lines research is proceeding.