... finally, the CAD-problem that had occured more than a year ago has been solved by simply downloading the edu-version of AutoCAD 2011. (Honestly, I had a couple of much more serious problems in the meantime.) -- In 2001, a student of us working on his diploma thesis had to design the wing for some kind of flying car - a cabin looking like a three-wheeled tennis shoe with propeller in the back and the wing on top. It was demanded to be an aerodynamically controlled tailless configuration. At least when testing a model in the wind tunnel (probably much earlier) it turned out that the elevons would have very short lever working against the low center of gravity. Therefore, the wing had a low aspect ratio and plenty of sweep. So, why not turn it the other way around and use the low center of gravity to stabilize and control a high aspect ratio wing, this way combining the performance benefits of an aerodynamically unstable airfoil with those of a tailless configuration? It should be quite easy, even easier than dealing with a rogallo. Additionally, one could avoid interference drag between wing and fuselage. Soon, it turned out that the stick forces would be as unstable as the wing itself. The only solution in my mind was a flap coupled to the wing´s incidence,a so called anti-flettner. his coupling would ensure the center of lift move aft with increasing lift and besides that ensure a favorable flap setting depending on lift coefficient. For very high airspeed, a negative flap deflection would have to ensure the wing being stable by itself, preventing the aircraft from toppling over. Later on I was allowed to initiate a couple of students´ projects that were to estimate the stability characteristics of such a configuration. The answer was always: It might work. So this example which I have recently been able to finish is a vision of a 20-m-sailplane, double seated in side-by-side configuration. The inner wing carries just flaps meanwhile at the outer wings they work as flaperons. The duck tail of the cabin is to produce a bit of nose-up pitching moment. The wing pylon together with the winglets works as vertical stabilizer, even though a bit of wing sweep will certainly be necessary. Please, view full size, the preview doesn´t look so fine. On 2009´s Aero exhibition in Friedrichshafen I spotted a vehicle that was pretty much the same what I had intended: A rigid wing rogallo mounted above a smooth aerodynamic cabin. The only difference: They had simply solved the stability problem with a small tail connected to the wing. This is surely a much more practicable solution even though mine still looks more elegant to me from an academic point of view. It is called the silent glider. http://www.silentfamily.de/ http://ecosia.org/images.php?q=silent+glider+m http://ecosia.org/images.php?q=silent+glider+e AutoCAD 2002, 2011 Corel Photopaint 7 Notepad