By Martin Feeg <Feeg14P@aol.com>

It's been 75 years since thermals were first utilised for soaring... or is it 76?

Let's dig deep into the ancient history of soaring. When in fact soaring was just developing from gliding. And almost every flight was a launch into new dimensions. Let's look at one developmental piece in the jigsaw.

Everyone knows Otto Lilienthal, the man from Berlin (Germany) who was the first to master gliding with self-made apparatus. All he did was shifting and twisting to steer the lot using his body weight, quite similar to hang glider pilots. In doing so he mastered 250 metres gliding down the slope of a hill. And shortly before dying he mentioned that it should be possible to stay aloft longer if only figure eights could be flown in the updraft of the hill. Yet, as well, he was certain that man would never soar from hill top to hill top. Unfortunately in 1896 his glider stalled. Running out of control he couldn't balance it and crashed with his glider. A few hours later he died from his injuries.
Aviation paused for a short while until the brothers Wright made headlines with their flyer. Selling their idea, as they always intended, started an avalanche in aviation. In 1909 the ILA -  "Internationale Luftfahrt Ausstellung" (International Aviation Exhibition) held in Frankfurt Main (right in the middle of Germany) propelled the idea of hang gliding and sailplanes. Clubs sprouted up, particularly in the near vicinity. Oskar Ursinus founded the "Frankfurter Flugtechnische Vereinigung" (Aircraft Engineering Society of Frankfurt) and in the neighbouring Darmstadt (50km to the south, on the eastern slopes of Rhein valley) the "Flugsportvereinigung" (Aviation Sport Society) was established. Mostly high school students and students of the technical university joined. They built not less than fourteen types of un-powered aircraft during that same year and tried them out on the slopes.
In 1911, for the first time they transported one of the crafts to the area of Gersfeld, 150km northeast, with the intention of finding better slopes. The Wasserkuppe was found to be the best area.
The dark years of World War I saw a dramatic improvement in powered aircraft. After the war Germany was not allowed to have powered aircraft. Still the hunger to fly was strong and led to the first gliding and soaring competition held in 1920. In recognition of the Darmstadt comrades, the Wasserkuppe was chosen as the competition site. A spirit arose and Wasserkuppe became the cradle of soaring; a place and stronghold throughout the storms of history. A man named Prof. Dr. Walter Georgii came to the competition to give meteorological advice. Since then he remained linked to soaring and became a backbone for soaring and meteorology likewise.
In 1920 everything was new and unknown. The whole layout of the aircraft was a big question mark. How many wings? What shape? Span? Depth? Thickness? Airfoil? Struts? Cover material? Fuselage or no fuselage? Where should the pilot be situated? Undercarriage or skid or pilots own legs? Every theory had its supporters and the discussions were vibrant, sometimes hot. These discussions were not just held amongst the young soaring pilots, either. Experts from many fields found their way to the competition to watch, discuss and get involved. Since than it ever was and will be: soaring is a melting pot for pilots, technicians, scientists and craftsmen. Still, or because of that, soaring developed quickly into a leader for aviation and meteorology.
However, on 31 August 1921, a most outstanding performance took place: the first glide of 5km, taking 13 minutes, was made. Over the next days the achievement was improved many times. Wind blowing up valleys was utilised and gliding transformed into soaring.
In 1922 a large amount of prize money was set for the first flight of 40 minutes soaring, return to launch point to set out straight away for a distance of not less than 5km. Everybody thought it couldn't be achieved the same year. Nevertheless, Martens found the answer. Don't fly straight into wind. Keep close to the slope and fly figures of eight. He stayed aloft for an hour and six minutes, with a best altitude of 108 metres above launch and a distance of 8.9km. During the following days record after record was set. But the big achievement of Martens was the idea. It was the key to ridge soaring and all the achievements over the next years and up until now.
Prof. Georgii called it the birth of soaring. It seems simple today, but then it had to be realised that the Wasserkuppe, being 400 metres taller than the surrounding area, forced the wind upward. This flight also launched a still lasting bond between soaring and meteorology. Think of the Mountain Wave Project or the Stratosphere Wave Project, both established to find out how atmospheric processes at high altitude influence lower levels and global weather. Sailplanes and glider pilots collecting data for meteorological scientists, as they have now done on numerous occasions for decades.
Up to 1926 flight duration improved continuously, to more than five hours. However, the distance was hardly improved upon at all. A record had been set during an expedition to Italy, measured at 24.4km. Then in the afternoon of 12 August 1926, Max Kegel launched into a just developing thunderstorm. With the clouds low and the Wasserkuppe high, suddenly he vanished into the clouds. Torrential rain and hail set in, everybody was fleeing to shelter. When the storm had passed there was still no sign of Max and worries crept to a climax. Phoning around the local area didn't bring relief - no record of man or machine. At 5:30pm the telephone jumped and Max reported himself and the glider unscratched. Checking the distance provisionally it was found to be an unbelievable 54km. This was the first cross-country flight in a sailplane leaving the slopes of the launch area behind.
Two years later the performance of sailplanes had improved again. More and more guns of the day tried to string the lift of numerous hills and ridges together. Out and returns became regular. While doing one such flight, Edgar Dittmar flew through a bubble of lift and achieved a new altitude record. In the same year, 1928, the emphasis was in use of frontal systems: get into one, climb to altitude while blown over the land, then glide down for more distance when the storm collapsed. Still, soaring was mainly clinging to the hills. The newspaper "GrŸne Post" announced a high price for the first flight of more than 100km in a straight line.
Let's briefly turn our view to the scientists. As we can learn from Wegener's Book, 'Vom Fliegen; Das Element des Fliegers', published in 1922: "of air movement up or down... resulting to mechanically balance temperature differences... an aircraft propelled horizontally by a prop getting into rising air, will get a knock under the wings and is pushed upwards heftily, so that the pilot will feel the same pressure in his head as if in a fast ascending elevator."
But it took six more years and Prof. Dr. Walter Georgii's attitude: "Soaring is not a pitying substitute for powered aviation, but has to find it's own place within aviation... valuable to engineering and science... with a particular job for meteorology." According to his book 'Forschen und Fliegen' (Exploring and Flying) thermal lift was discovered 30 April 1928. Let's have a closer look.
"The sky was rich with nice little cu's. Above one corner of the Old DarmstŠdter Airfield a cloud had formed where I had observed it so often. The decisive day had arrived... I called Johannes Nehring and a few of the DarmstŠdter students to meet me on the airfield. I ordered Nehring, test pilot of the institute, to fly to the base of this repeatedly observed cloud with the G.M.G. 1a (a light aircraft). He was ordered to shut down the engine completely once he had arrived and fly in shallow banked orbits underneath it. We watched Nehring's flight with some tension. He approached the base, switched the engine off and flew in shallow circles along the margin of the cloud. What happened? The G.M.G didn't glide down, she didn't lose altitude, but remained for 10 to 12 minutes in soaring configuration with the prop still standing under the cloud. After the landing we jumped onto the barograph to see the flight trace. Undoubtedly it showed the flight without loss of height in spite of the prop standing still. It allowed us to calculate a lift of 4 to 5 m/s at the cloud base; without doubt a much stronger vertical velocity than ever found while soaring the hills of the Wasserkuppe. The afternoon of 30 April 1928 delivered a great moment for soaring."
The very same day Walter Georgii headed for the Wasserkuppe and advised the young instructor Robert Kronfeld to fly with the new sailplane "Professor" to one of the cumulus clouds and circle in the thermal lift. Georgii asked Kronfeld to keep it a secret until the Wasserkuppe competition of the same year.
So, why didn't we see everybody soar like a bird, but staying in the ridge lift as described above? Facts of history show that until the summer of 1931, most likely only Groenhoff and Kronfeld had a variometer and they kept it highly secret. Undoubtedly the strongest lift is found under frontal storm clouds. With only the aid of a bottom it was likely to be the only lift to recognise.
And what happened to the reward for the first 100km flight? Nehring thought to achieve it along the  black forest sloping down into the Rhein valley. He would need nice westerly winds, strong enough to give him enough altitude to jump valleys breaking through the slopes. Kronfeld, however, preferred the Teutoburger forest; rather shallow slopes, not as long and nicely set as the black forest. Still, they would provide some lift to stay aloft. More important to him, the area was well known to produce nice, rich, small cumulus. Kronfeld's idea was to use a mix of both to snatch the reward. The ridge lift area along the Teutoburger forest was rather small, difficult to work and interrupted by four large gaps. He had already had a few attempts when willingness of supporting comrades and his holidays were rapidly drawing to an end. Then on 15 May 1929, against all hope, he achieved the distance and got the reward.
However, the real breakthrough regarding thermals came in 1931 as aero tow, auto tow and winch were introduced, along with better instruments, thus allowing the free-flight pilot to leave the ridges behind and pioneer the flatlands.