The development of the glider which allows man to experience something approaching the effortless flights of the sea gull and the hawk
BEAUTIFUL CLOUDS THAT HELP THE GLIDER. This graceful soaring plane of special high-efficiency type is starting a flight near Breslau. The clouds, with shafts of sunlight piercing through them, which form such a striking background to the plane, have another importance for the airman. Such a formation as that towards which he is going would have rising columns of air beneath it, providing an abundance of lift to draw the glider upward and help him on his way across the countryside.
GLIDING flight, or flight on an engineless aeroplane, before 1919 regarded as a field for experiment leading towards “motoring in the air”, has assumed an importance unforeseen even by enthusiasts. Instead of departing into the limbo of useless things, it has become a highly important branch of aeronautical practice. A man has kept aloft in the air for a day and a half in a heavier-than-air apparatus without means of propulsion; another has travelled the amazing distance of 310 miles.
Even greater achievements, doubtless, are in store, and further improvements in the apparatus; and it is equally certain that engineless flight will, within limits, be capable, very shortly, of serving practical purposes.
No one can say what turn events would have taken had there been no First World War, but it is easy to see that the restrictions imposed by the Allies upon conquered Germany, by which our late enemies were prevented from developing high-power aircraft, caused them to direct their energies to research of another kind. Doubtless they would have done this in any case, but the incentive was all the greater in the circumstances. And they set to work in good earnest, and produced remarkable results.
Their example inspired Britain, and there was a glider meeting at Itford Hill, near Lewes, in 1922, which proved the occasion for a gathering of many flying pioneers of this and other countries. Of the visitors, the most notable were Anthony Fokker and the Frenchman, M. Alexis Maneyrol. Some good performances were the result, but as most of the gliders were of a primitive, unairworthy character the flights made, both in distance and duration, were elementary judged by modern achievements.
FOKKER IN A BIPLANE GLIDER. The success achieved in Germany with the revived art of motorless flight during early post-War years, encouraged enthusiasts in all other countries. England quickly took up the sport, and to such effect that in 1922 a successful gliding competition was held at Itford Hill, near Lewes, Sussex. Amongst the competing pilots was Anthony Fokker, the world-famous aeroplane designer. Above, Fokker is seen in his biplane glider taking off.
British experts, generally speaking, failed to see any practical purpose in gliding, and they turned their attention towards low-powered aeroplanes, or “power gliders”, as they were called by some people.
Meanwhile, the Germans and the French remained faithful to the glider, and especially to its more advanced form, that of the true cloud-soarer, and eventually Britain was shaken out of her indifference. Many gliding clubs were formed, a British Gliding Association was constituted, and the promise of Government assistance obtained.
Once the possibilities of long-sustained flight on motorless aeroplanes are grasped, the fascination of it is irresistible. It is the very poetry of flying, for it is the nearest approach to the flight of birds that Man has yet realized. No roaring of engines, no fumes of petrol, no smearing by dirty oil; the winged machine slides through the air, and no sound is heard except the music of air sweeping over wings and wires.
Below the hill a man is at work in a field. He is intent upon his work and, for several minutes at a time, he does not raise his head. A big shadow sweeps over him swiftly. It is not that of a cloud, for the sky is clear; it is far too big for any bird. Startled, he looks aloft. No more than a hundred feet above him is a graceful winged apparition. He does not hear a sound until “Hallo!” a voice from the skies greets him. He is too astonished to reply.
To the British, the principal object of gliding is sport, although if you visit a gliding club you will hear much eager discussion of thermal currents, of cloud “streets”, of thunderstorm soaring, and technicalities concerning a wonderful new world. It becomes clear that gliding is shedding new light on the whole science of ways of the air, and may contribute important new matter to flight. Clearly, it may be important to the aeroplane pilot, enabling him to obtain experience at small cost, and giving him confidence; it gets him over what is, to some, the frightening first ordeal of trusting to air.
A vast field of study is opened up. So sensitive is the soaring apparatus that the radiation of heat from a field of bright-coloured flowers affects the flying. A slight downward tendency is felt over a pond, or a row of trees. A group of houses, especially red-tiled ones, sends up a current so definite, that soarers deliberately take advantage of it.
TOWARDS THE SOARING STAGE. In the early stages of training the glider pilot, the pupil flies an elementary machine with which short, low glides are made. When proficient, he passes on to a secondary type, capable of limited soaring flight. Finally he flies the sailplane proper, the most advanced of all motorless ’planes. This photograph shows a secondary machine of the Prufling type, at the moment of release.
There are several different types of apparatus, from the beginner’s to the record-breaker’s, with its enormous span of narrow wing. Gliders are launched by elastic cords, or by motor cars. Sometimes they are towed aloft by an aeroplane, and then released. In still air some types have a gliding gradient of i in 30 and slopes even more gentle than that.
Many experiments with trains of gliders have been made, an aeroplane towing three or four, each with its pilot, and each to be released as desired. Mail-carrying and war operations are foreshadowed by such experiments, in which Russia is taking very great interest. Wireless apparatus has been carried in soarers, and there have been many-soaring flights at night. Gliders for ten or a dozen passengers even are promised.
At the great Rhon meeting in 1935, the sixteenth annual meeting of the kind, the total distance flown in the fortnight was approximately 22,000 miles, and the number of launchings was 513. Thus, the average distance per flight was 42 miles. It would have been a remarkable total even for a power-aeroplane flying meeting.
Britain had a 9 days’ meeting at Thirsk, Yorks, in August, 1935, and in spite of bad weather there was more than 133 hours flying.
Germany set the pace in long-distance soaring; but the world was startled in January, 1923, by a soaring flight of 7 hours, 3 minutes, in Algeria, by Lieutenant Joseph Thoret, a French officer. Such flights are made by ranging to and fro over a region of ascending air, and are monotonous to watch, and, as a rule, monotonous to perform.
Lieutenant Thoret’s flight was followed by many long duration flights of the kind, and in 1926, Herr Max Kegel flew a distance, measured in a straight line, of 34 miles, and in 1929, Herr Robert Kronfeld flew on a glider a distance of 62 miles. At about the same time the duration was sent up to 15 hours. Kronfeld came to England, and promptly did a 70 miles glide from Itford to near Portsmouth, using the South Downs air currents. In August, 1930, he did glides of 93 miles and 100 miles. He and others crossed the Channel, but in these cases they were towed aloft by aeroplanes. Kronfeld has crossed the Alps by a glider, a feat also performed in September, 1935, by Schreiber, who was released from an aeroplane. Kurt Schmidt, in August, 1933, stayed up for 36 hours on a course to and from Patersort and Korschenruh.
AUSTRIAN ACE OF MOTORLESS FLIGHT. Much of the popularity of gliders and sailplanes is due to Robert Kronfeld, a young Austrian airman. His demonstrations of the possibilities of this most graceful development of flight, not only in his own country but in Germany and Great Britain, have fired many “airminded” young men with a desire to emulate his feats. This photograph shows his sailplane “Wien”, with which he achieved several long-distance and height records, in flight.
It was not long before accidents occurred, due in most cases either to the collapse of the apparatus in the air, or to mishaps in launching. Improved launching methods, the observance of certain precautions when a motor car is used, and the stressing of the wings, calculated for the forces with which they have to contend, will go to the root of the matter. Unfortunately, it is not always possible to eliminate human error or folly. For spectacular purposes men loop-the-loop in gliders, and, provided the machine has been certificated for aerobatics, there is no reason why looping-the-loop should not be safe in good hands. Not so as yet, is the “inverted loop”, which the late G. E. Collins was attempting when his machine broke, and he was killed.
The machine on which G. E. Collins did many of his big flights was a “Rhonadler”, with a span of 57 feet, and weighing only 364 lb. (There are, however, gliders of much greater span.) On one occasion Collins described the sensations of soaring:
“There is no sense of danger at these heights. You float like a man in a comfortable armchair, lulled into happiness by the fact that all movement seems to have died away. The birds are far below you. No thought of danger enters your head. The celluloid cockpit-cover protects you from the wind. You have realised the dream of man through the centuries — to soar as the birds soar, as free as the air.”
UP AND AWAY. With a swift rush forward, a sailplane, launched by means of an elastic rope, sweeps out over a valley ready to rise on air currents rising upward from the lower ground. Here is a typical scene at the London Gliding Club’s site on Dunstable Downs, Bedfordshire.
But it is not always so pleasant. Take, for example, an early experiment by Mr. H. Bergel, who ascended from Dunstable, and flew to Hornchurch, in Essex, July, 1935:
“As a last resort before landing ignominiously at Radlett (a bare ten miles from Dunstable) I made for some red-roofed villas grouped together. Thank Heaven, it worked, and again I settled down to interminable circling, at last reaching cloud-base level at 3,400 feet (the clouds were steadily going higher).
Once again I set off east. Once again I lost height very rapidly, till I reached Southgate (or thereabouts) at 1,200 feet. Once again, in desperation, I went for houses, and in particular a burning rubbish dump. And again it worked (I smelt the rubbish dump half-way up), and I went round and round and round till I got to 3,800 feet (cloud-level again).
After that it was a bit of a nightmare. I found I was in sight of — London Bridge! I raced off east, circled a bit off the Mile End Road, got to Barking and circled a bit more. I now had my eyes on what looked like a usefully flat and open field running down from a main road to the Barking Power Station. As I was then losing height I kept my eye on it as a hopeful landing ground. When I was down to about 1,800 feet I looked a bit closer, and found that the whole field was one gigantic web of 133,000-volt cables!”
British gliders, although not yet among the world-record breakers, have proved highly efficient. One type was designed by an ex-corporal mechanic of the R.A.F., and on it Flight-Lieutenant E. L. Mole, in 1933, made a flight of 7 hours.
Another machine of British design and construction deserving of note, is the “Scud”. Unlike other soaring craft, it has quite a small wing span and a metal tubing figures in its assembly.
For obvious geographical reasons, it is difficult to achieve in this country the distances covered by gliders on the Continent. The wind is seldom in the right direction to give sufficient distance over land.
The distance record steadily increases. Starting from Mount Wasserkiippe, Prussia, on July 29, 1935, four German pilots beat the new world record just set up by Ludwig Hoffman’s flight of 297 miles. The four pilots — Brautigam, Oeltzschner, Steinoff, and Heinemann — all landed at Brno, in Czechoslovakia, a distance of 310 miles.
RUSSIAN EXPERIMENT. Modern Russia is keenly interested in the development of engineless flight, and much research work has been carried out in recent years. Here is a sailplane, slung beneath a balloon, before being released for a flight. The object of the experiment was to test the effectiveness of carrying the machine into an area where air currents would at once provide it with lift several hundred feet above the ground.
or obvious geographical reasons, it is difficult to achieve in this country the distances covered by gliders on the Continent. The wind is seldom in the right direction to give sufficient distance over land.