The “Eta Biter”: Dick Butler’s ASW-22DB

In the year 1999 I purchased a new ASW22BL after taking a leave from soaring for 15 years. The first shock I had in purchasing the ship was that it cost three times what my first ‘-22 cost in 1980, and the second was that it had basically the same performance. What I realized was that in the open class of competition sailplanes there had been no significant improvements in performace for the last 20 years, while the other sailplane classes had made significant performance increases from advances in both aerodynamics and structures.

After numerous discussions with my close friend Gerhard Waibel, we decided it was possible to build a new open class (NOC) sailplane that would have a  measureable performance increase from the ASW22BL using modern aerodynamics and structural materials. Prior to this NOC we first wanted to verfify many of our ideas in aerodynamics and structures on a test sailplane, so the ASW22BL became our beta ship. Items such as handling qualities with new vertical and horizontal tail volume coefficients, new airfoils, an air extraction system, retractable tail wheel, high modulus materials, etc. were all part of the program needed to verify our ideas for a NOC. After talking with Edgar Kramer of Schleicher and Loek Boermans of Delft and persuading them to support us in the project, we proceeded to go ahead with it in the year 2000. The following presentation highlights some of the ideas and results of this program. Somewhere along the adventure, Gerhard and Hans Werner Grosse named the ship the “Eta Biter” and the moniker stuck.

ASW-22DB (Eta Biter) Evolution

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