Bill Johns asks: >I would think that each airfoil has an optimum cg, right? > > >I would think that planform influences how one determines the cg relative >to any airfoil. IE: a 7037 might be optimum at for instance 40% of chord >[I'm pulling that out of the air (no pun intended) I don't know what it >actually is], but planform might influence where at the root chord one >actually balances to. Is this correct? Well, yes and no. C/G is a function of almost everything in the entire design. In our experience, the airfoil can have some influence on the C/G, but it's really one of the weaker influences. We've gone through quite a few different airfoils and planforms on the Monarchs and Wizards over the years, and found that planform changes have a surprisingly small but significant influence, but airfoil changes have a very minor influence. Tail volumes and moment arms are one of the biggest factors, and even fuselage shapes can have a significant effect. The other consideration is that C/G also influences yaw stability, not just pitch, and on some designs (particularly flying wings), finding a C/G that satisfies both yaw and pitch requirements simultaneously can become a rather tricky problem. Don Stackhouse @ DJ Aerotech [EMAIL PROTECTED] http://www.djaerotech.com/ RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
