{"id":13748,"date":"2016-12-08T18:53:01","date_gmt":"2016-12-08T17:53:01","guid":{"rendered":"https:\/\/www.dg-flugzeugbau.de\/en\/?page_id=13748"},"modified":"2017-01-04T14:53:33","modified_gmt":"2017-01-04T13:53:33","slug":"two-seater-dg-1000","status":"publish","type":"page","link":"https:\/\/www.dg-aviation.de\/en\/library\/two-seater-dg-1000","title":{"rendered":"Two-Seater DG-1000"},"content":{"rendered":"
The following article was first printed in the December 1998 issue of the Aerokurier
\nand is reprinted here with the kind permission of the Publisher.<\/p>\n
Two-Seaters enjoy a market revival. In the model series of the DG Sailplanes this lead to the several variations of the DG-500, which pretty well covers the market. In the anniversary year “25 Years DG Sailplanes” a modern successor, the DG-1000 appears.
\nThe new Two-Seater of DG Flugzeugbau in Bruchsal is entirely a child of the times. Swept back and upward pointing wingtips continue the modern wing geometry first seen in Schempp-Hirth sailplanes and now spread through the entire series of the Swabian manufacturer. It makes for good handling, and especially excellent thermalling behavior.
\nAfter about ten years of production of the DG-505 with straight wings the DG-1000 will replace it. In various models the DG-1000 will not lag behind it’s predecessor 500. The 1000 is planned in two wingspans of 18 M and 20 M. This will ensure optimal conditions for both instructing and cross-country \/ contest flying.
\nThe performance requirements for the new two-seater were ambitious.In the opinion of the Chief Designer Dipl.Ing. Wilhelm Dirks studies showed that it should be possible to develop and build a sailplane that exceeds the performance of two-seaters with 20 m spans. In the spring of 1997 this gave DG-Flugzeugbau the impetus to start the DG-1000 project.
\nBesides excellent behavior good performance was also the aim of the development. The projected data are very promising. Best L\/D with a wing loading of 42.8 kg\/m2 (20 m version with maximum take-off weight) should be 46.5. Minimum sink with a wing loading of 28 kg\/m2 (20 m version with 80 kg crew weight) should be 0.51 m\/s.
\nThe good behavior and performance should be the result of a new wing and tail plane. The fuselage of the DG-500, with modifications in the landing gear and cockpit area, will live on in the DG-1000.
\n<\/a>A laminar profile by Horstmann\/Quast of the German Center for Air and Space (DLR) in Braunschweig was selected as the wing profile. There were two choices. The alternative promised the best possible performance in slow flight, but this had to be bought with lesser performance in the higher speed areas. Wilhelm Dirks also suspected that there might be problematic behavior in slow flight. That is why it was decided to use a profile that promised minimal reduction in the area of best glide angle, but which showed considerably better performance in the area above 160 km\/h. Harmless stall characteristics and little sensitivity to bug and rain degradation seem to be assured.
\nThe profile selection was guided by what can be achieved in praxis. Wilhelm Dirks says: “We believe that the minimal advantage of the first profile could not be achieved in real flight situations, but the harmless stall characteristics and minimal sensitivity to bugs and rain are extremely important.”
\nA number of scientific institutes were involved in the development of the wing. The profile developed in Braunschweig was tested in the wind tunnel in Stuttgart. Professor Loek M. Boermans of the Technical University in Delft optimized the wing root to fuselage section and calculated the winglets. Wilhelm Dirks designed the basic wing geometry for the best possible lift distribution by using a 4-section trapezoid. Winglets further improve the slow flight characteristics. For best thermal behavior the outer sections of the wing of the 20 m variant are bent upwards. This wing geometry has proven to bring stability while thermalling.
\nThe upward bend of the outer wing played a role in the development of good ground handling. The angle is so large that the down going tip cannot drag on the ground. Says Wilhelm Dirks: “This ensures that the danger of a ground loop is no greater that in a sailplane with conventional wings”.
\nAs in the DG-505 ORION the wing is divided at half span of 8.6 m. For the 18 m version the basic span of 17.2 m is extended by wing tips of 0.4 m. The extend to mini winglets. This provides a useful training sailplane with docile flight characteristics and a good roll rate. The 18 m version of the DG-1000 will be licensed as fully aerobatic.
\nWith wing tip extensions of 1.40 m, into which the ailerons are extended, the 20 m version of the DG-1000 for cross country flying and contests, is created. These wing tips can be had with integrated winglets. All connections are automatic, as expected in a DG sailplane.
\nThe tail surfaces are also new developments. The elevator follows the trend of the times with a double trapezoid shape. With this elaborate planform the necessary, but in drag elements detrimental, part of the steering units has been optimized for good performance. The slim, high rudder shows it’s relationship to the 500. Its as high but has a greater aspect ratio which makes the fuselage 10 cm shorter. Both elevator and rudder get new profiles.
\nDrag is saved on the fuselage, too. A new retractable gear with a further forward moving wheel (similar to ASH 25 and fs-31) eliminates the need for a forward extra wheel as in the DG-500. The 1000 will stand higher and has more ground clearance.
\nAside from the performance improvement the new wheel configuration also improved the start behavior. Because of the positioning of the main wheel and tail wheel there is no tendency to oscillate when starting, or the tendency for the tail to crash down, which is especially noticeable in three wheel configurations and which launches.
\nThe wheel housing on the DG-1000 remains behind the pilot seat. A cleverly designed movement of the gear avoids bringing the gear into the area of the copilots lower back, which is the case in a conventionally designed gear. In the design of the cockpit the latest safety designs will be incorporated.<\/p>\n