OK, I was hoping someone that really knew what was going on would answer this, but it seems that isn't going to happen. SO, Here goes..... The reason for sweepback has to do with the high pressure sound wave crossing the wing and the control surfaces. If the wing is swept, only a small portion of the surface sees the pressure wave as it crosses, if it isn't swept, the surface gets locked up or buffeted by the wave. So the sweep is needed for speeds nearing or transitioning through mach 1.0 The down side of sweep is that it creats huge amounts of span wise flow across the wing which also increases the already huge tip vortices. Anhedral helps counter act the span wise flow as well as diminishing the stabilty that is created by the sweep. Any additional info from someone who ha actually been involved with the process would be extremely appreciated! Mark Mech [EMAIL PROTECTED] www.aerofoam.com RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]