Thomas, I'm still trying to figure out how the Sharon 3.7 does it. The Sharon's flew beautifully this last weekend in Phoenix. Great plane for the "mid" winds and thermal cycles they had at the contest.
The Sharon has a 7037 at the root, transitioning to a RG-15 at the tips. Seems totally backwards; more camber at the root than at the tips. This is aerodynamic washin unless there is some twist in the molding process. JE -- Erickson Architects John R. Erickson, AIA > From: "Thomas Koszuta" <[EMAIL PROTECTED]> > Date: Tue, 8 Feb 2005 15:30:49 -0500 > To: <[email protected]> > Subject: Re: [RCSE] The perfect platform or Not.... > > You can only optimize a wing with one airfoil for one speed. You then > either need to compromise for good performance at more than one speed or > accept the poor performance at other speeds. The old floaters are good > examples of this. This is one of the reasons that camber flaps are so > popular. > > The alternative is to blend the airfoils to get aerodynamic washout and > decreased stall speed at the tips. Martin Simons book describes this by > using more camber at the tips, then using geometric washout to bring the > aerodynamic AOA back to the same value. I have taken to this by using > something like SA7035 at the root (2.5% camber) and SA7038 at the > tip(3.25%camber) with the SA7036 and SD7037 between and washing the whole > wing out. It is a near continuous twist to about 0.75 degreees - the > approximate 0.75 degree (estimate) difference in zero lift angle. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
