POLISH FLYING EXPERIENCE WITH TAILLESS GLIDERS

Abstract

The tailless aircraft named "Lotnia" was the first ship designed by Polish flying pioneer Czeslaw Tanski in 1894. Then followed: "Dziaba" designed by Stanislaw Malinowski, 1923; JN-1 " Zabus" designed by Laroslaw Naleszkiewicz, 1931; SZD-6x "Nietoperz" designed by Wladyslaw Nowakowski and Fustyn Sandauer, 1951; SZD-21x "Wampir 2" designed by Jan Dyrek, 1959; "AV-36" CR designed by Charles Fauvel. This ship was bought from  Austria for comparison studies. The regular flight test reports were available for the last three types mentioned above only, so their flying properties could be described. SZD-6x "Nietoperz" was tested in three variants having different yaw control system arrangements. More than 50 flying hours were completed during the factory tests. Now "Nietoperz" is displayed in the museum. SZD-2x "Wampir 2" was destroyed in a flutter case accident in its 14th flight. Box SZD types, with swept-back wings, were very sensitive in the turbulence in the wake of the towing aircrait. AV-35CR obtained a Polish C of A and is used even today by the Student Flylng Club of the Technical University, Warsaw, with its straigh twing, its behaviors rather similar to that of conventional ships. All types showed a tendency to nondamped short-period pitching oscillations in gusty conditions. This limited the thermal flying tests considerably. Now these three tailless gliders belong to  history. None of them meets the requirements for acceptable flying-properties and performance. Tfe rapid development of conventional sailplanes has pushed the tailless concept aside. To smooth this conventional-ships domination, the idea for designing the moden tailless models like SB-13 arose.