As per the subject, does anyone know where/how to find a reasonable formula to calculate this torque. For your info Multiplex site doesn't work for an all moving elevator, at least so it seems to me ( equating control surface chord and span with the wing ones give negative results). Result will be applied to my next "lethal weapon" for DS. TIA. Ciao. Tullio. Ing. Tullio BONFIGLIO Ansaldo Energia ICI/IMT/AUT - F12 / P5 Via N. Lorenzi, 8 16152 Genoa - ITALY Ph. : 39 (0)10 655 3267 Fax : 39 (0)10 655 3814 / 3894 E-Mail : [EMAIL PROTECTED] RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]