What Is Dive Testing?

There is much dilemma over how to conduct and interpret "dive testing" of a sailplane. What is typically asked is, "hey, your plane isn't flying 'right', have you done a 'dive test'?"

What dive testing usually does tell you is whether the decalage angle (the angle between a wing and horizontal stabilizer) is 'right' and the resulting pitch stability of your plane. From this you can guess at your plane's relative CG position.

How to Perform a Dive Test

Start from a relatively high altitude. Dive the plane to pick up speed and neutralize the controls (let go of the stick) and watch what happens:

  1. The plane pulls out of the dive. This means the plane is nose-heavy or has positive stability. A gentle pull-out is ideal.
  2. The plane 'tucks' under or accelerates in the direction it's travelling. This is dangerous — the plane is tail-heavy and has negative stability. Add nose weight or adjust the CG forward.
  3. The plane remains in the dive. This means the plane is neutrally stable at the current CG. This can be fine for experienced pilots but is not recommended for beginners.

See also: About Decalage · CG (Center of Gravity)