AIR CYCLING.

Evening Star, Issue 22571, 12 February 1937, Page 7

AIR CYCLING.

dne-man aeroplanes NEW GERMAN "SPORT" " Command of the air ” to post-war Germany is what “ mistress of the seas ” has been to Britain since the days of Elizabeth. In a word ■ “ safety.” V.'hat Germany has achieved in airmanship since 1919 has provided the world with sensations in plenty. But what we know of her attainments is far from being all (writes the Berlin correspondent of the Melbourne ‘ Argus ’). When a German speaks of “ command of the air ” he does not mean that Germany is to be made numerically superior in air force to all other countries. What he is really thinking of is that German airmen should be as completely at home in the air as birds. This is most. 1 strikingly illustrated by another record performance in human flight attained at Fulsbuttel, near Hamburg, on November 21, when a young pilot, Heinrich Hofmann, of Offenbach, in a machine constructed by two German engineers, Haessler and Villinger, flew 427 metres in an “air bicycle” driven by muscular power, beating his own previous record of 390 metres established last year. The record has been officially attested. Commercially, it has been asserted, one-man power muscular flight, even if it were successful, would be of no value. Watt’s discovery of the expansive power of steam might also have met with the same criticism at the time. What Hofmann’s performance is worth as a contribution to the future of flying may be gauged by what has been learned of aerodynamics through the sport of gliding. Who could have foreseen that the first flight of the Wright brothers on December 17, 1903—a distance of 35 metres in 12 seconds—would have led to such a future? But, short as it was* it proved that flight in heavier-than-air machines was a possibility. To-day, given unlimited power, almost any desired result as regards speed, altitude, or distance can be reached. But what has been engaging the thought of German scientists, engineers, and airmen for several years is the fact that birds fly incredible distances, remaining in the air for days with apparently no effort at all. German experimenters are trying to discover how this is done. That was why, in July, 1933, the Frankfurt Polytechnic Society offered a prize of 5,000 reichmarks to the first person to fly a distance of 500 metres between two fixed points and making two stipulated turns, using no other energy .of propulsion than human muscles. Supplemented by such power as could be stored by a compressed air hand pump or by thick rubber bands twisted tightly by the pilot himself within not more than half an hour of the start. This offer set many people experimenting, but the only ones who have achieved any conspicuous success are. the two engineers, Haessler and Villinger, employed in the glider-making department of the famous Junkers works at Dessau. Experimenting in human flight became their hobby. The limited amount of time at their disposal explains why progress was not more rapid. All their work has_ been based on what they know of gliding, learned at the Junkers works. Selfstarting gliders can now be constructed with auxiliary motors as small as from to 3 horse-power. 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 into the region where thermal air currents, flow the problem would be solved. But researches made by the famous athletics physician Professor Brustmann show that while fast 100metre runners can exert as much as 7h.p. for 10 seconds, and rowers in training 2 to h.p. for about 10 minutes, the average human being cannot continue for any length of time at more than J-h.p., in exceptional cases 4-Sths-h.p. So the solution would depend on the possibility of making a glider that pould be raised into the upper air without this amount of energy. At first sight it would seem extremely unlikely that this could ever be accomplished. The lightest machine ever made -weighs 50 kilogrammes (a kilogram is about 2,2051 b) and the average pilot 75 kilogrammes. So a weight of 2751 b would have to be lifted about 250 ft. The heaviest flying creatures found in nature weigh scarcely one-sixth to one-eighth of that. In gliding no power is exerted at all once the pilot has reached the region where thermic air currents are in motion. Gliding depends on these currents. In still air the glider 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 all, it is gliding, pure and simple. • To judge from Hofmann’s latest performance, Haessler and Villinger are likely to win the Frankfurt Polytechnic 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 of glider. It weighs 50 kilogrammes, has a breadth from one wing-tip to the other of 13f metres and a length from nose to tail of 5} metres. The wooden propeller, attached just in front of the pilot’s pit, measures one metre (39.37 in) from tip to tip, is worked entirely by pedals, just as if the polit were cycling, attaining as many as 500/600 revolutions a minute. The pilot steers with his hands, the tail being fixed and the altitude regulated by movable fins on the wings. Experiment shows that all the power that can be stored in twisted rubber hands is 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 rigid. Birds overcome gravity by flapping their wings. A glider can do nothing in a calm. But birds, as it were, generate with their wings the wind that enables them to fly. Hence experts agree that the problem of muscular flight can be solved only with a machine with movable wings. Along these lines research is proceeding.