Originally Posted by eflightray
Are you saying that an airplane with a symmetrical airfoil would always pitch up with increased throttle ?, not matter how it is set up ?
That it will react the same as a positive cambered wing with increased throttle ?
Perhaps I have just always got it wrong, that the reason for using a symmetrical section as used by pylon racers, aerobatic model etc, was that they don't noticeably change pitch with throttle.
I wasn't saying anything. I was asking a question. But since you brought it up, yes, a zero camber symmetrical wing will pitch up with increased throttle just like a cambered airfoil. That is with the caveat that the airplane has positive longitudinal stability. If it has neutral longitudinal stability then it will not pitch up with increased throttle. But then, neither will a cambered airfoil with neutral longitudinal stability.
As far as using symmetrical wings on aerobatic models and pylon racers is concerned, aerobatic models use them so they fly basically the same inverted as they do upright. Aerobatic models are also usually set up with neutral longitudinal stability so the pitch angle doesn't change with throttle change. Pylon racers would use thin symmetrical airfoils to reduce drag. A symmetrical airfoil has the best lift to drag ratio. Pitching up with increased throttle is eliminated on pylon racers basically by setting up the relative angle between the wing and the horizontal stabilizer, sometimes called decalage but more properly known as longitudinal dihedral, so that the plane flies level at full throttle. In that case it would tend to pitch down strongly with decreased throttle.