I tihnk that is a bad statement. Every gyro will have some amount of precession. Precession is how an axis drifts. Remeber as a kid you put a gyro on a string and its spinning axis would spin onthe string. This is precession. "University Physics" Ninth Edition Young and freedman. No whether it is noticable or usable on thsi scale is another story. Precession exists because there is no such thing as a perfect system. The mass of a gyro is not perfecty centered and evenly distributed. There is friction in gyros. Precession is a bad term to be used, you might mean the gyro scopic forces involved. Forces on a gyro also have the components of centripital accleration and tangential velocity. I know this is more than you wanted to know but I am almost done. For those of you with higher math skills the normal force on a gyro is the cross product between these to vectors. This is part of what causes the forces you see in flight. On a spinnign disc the force acts 90 degrees to where it is applied. Just because you prop does not weigh as much as a real Ex. 300 prop does not meanthe forces are not there.