Since the middle of the 80’s Walter and son Clemens Zahn took part at model airshows in Germany and in other countries. They became recognized by the huge models they built. Walter Zahn built for example a Grunau Baby, a Minimoa, a Lo 100, a Moazagotl (10m wing span), and also a DFS Habicht E (all 1:2). Clemens had to build the towing planes for the huge gliders. He built for example a Klemm L20, a PZL Wilga and a Morane Rallye. Grandson Christoph was allowed to run with the wing tip of his grandfather’s gliders. When he was older he was allowed to fly the tow planes of his father in front of the audience. So he had no other possibility than begin with gliding from the age of 16.
During the gliding education of Christoph his father and grandfather thought about scratch-building a glider for him. Once they knew that the glider must be a Habicht, it was clear that the building would not be easy, and also, there was no flying Habicht at that moment. The Wasserkuppe Habicht was a static exhibit in the museum. To get the plans we asked Theo Rack, the head of the museum. It was inconceivable that Mr. Rack would take these 3 model aircraft builders serious, when they told him the idea. They were really happy and relieved to get the plans. When they arrived home they began to study the 430 plans. They saw again, that it would not be an easy job. It was a bit different from building a model glider, although some things were nearly the same.
After a few evenings over the plans, the fuselage building was started. The Habicht is a fully aerobatic glider, but the former and the straps did not look strong enough. This first doubt disappeared when the straps were fitted to the fuselage. After the final planking the resistance against torsion was fine. The area of the pilot’s seat and the inside of the cockpit was planked with plywood. Hans Jacobs found the best combination between weight and strength. When the building of the fuselage was finished the wing building began.
A lot of patience was needed for the building of the ribs. After three months of rib-building the most interesting and complicated part began; the mainspar. It is a box spar and has the characteristic gull bend. The wood used for the mainspars had to go through many tests at the technical university in Darmstadt. Before closing the mainspar box the inspector had a detailed look at every part of the spar.
The next interesting job was forming the D-box of the wings. The 3mm thick plywood was steamed in hot water and laid up on the nose ribs whilst drying. When it was completely dry it was fixed with glue. The attachment and activation of the huge ailerons is a complicated affair. When the stick is moved there are 44 ball-bearings working just for the ailerons.
One couldn’t buy any metal fittings for the glider. Clemens Zahn needed one year to finish all the metal fittings by himself. The welding was done by Fa. Eichelsdörfer in Bamberg, because a special welding education was required. Also the 23 inspection hatches were made in aluminium by Clemens himself. The windshield was moulded from 3mm plexi-glass. The form was done by using heat. The upholstery of the cockpit and the pillows was done by grandfather Walter. He is a skilled tailor, so it was no problem for him. The unsupported areas of covering were done with cotton and a 30g/qm perlon weaving was used to cover the wooden planked parts of the wings.
The wings are painted with the characteristic aerobatic sun-burst. The stripes were done with red colour. It is known that one red Habicht existed in the past. The sign-writing was done by Clemens and Christoph.
On the home airfield „Altenbachtal“ in Obernau only winch launches are possible, so the Habicht needed a well-positioned release hook. Part of a fuselage model was build to show the position of the release hook. The position was calculated and fixed by inspector Jochen Och. The German aviation organisation checked it and confirmed everything is all right.
After finishing the whole job the point of gravity was checked. The empty weight is 241 kg. In the book the empty weight was given as 250 kg. So 9 kg were saved and could be put in as the glider ballast of 109kg. The first flight could take place.
The first flights were done with aero-tow. No problems. The releasing of the wheel dolly was no problem. Also the winch launches were good. The first thermal flights were done and the slow
flying qualities are amazing. The aerobatic qualities are perfect said Christoph after his first flights.
Building the Habicht was not an easy but all the time an attractive project!
(Thank's for helping with the translation Graham; a perfect english aerobatic pilot)