Today, I played with styrofoam gliders with my kids; I made an asymmetric wing, asymmetric horizontal tail, symmetric vertical tail, and attached these to one stick for the fuselage. I've had big problems with pitch stability, so I played with adding mass to the nose, hoping to solve the problem.
Every time I throw a glider with my hand, the nose lifts up or falls down (which one depends on where I set the glider's center of gravity), and the glider crashes. I set the tail to produce downforce, but I can't find the right pitch balance to make the glider fly well.
I know that, for level flight, the CG has to be in the same place as the glider's overall center of lift (both wing lift + tail lift).
Should the horizontal tail have a symmetric or asymmetric profile, and what should the angles of incidence for the wing and tail be?
Maybe the best way is to put the CG at the wing's center of lift (at the 25% chord line) and set the tail to a neutral position (producing no positive or negative lift)?
What is the easiest way to calculate where to place the CG if I don't know how much lift is produced by the wings and tail?