RE: ground loop? explain?
Ground loop is also caused by gyroscopic precession, I thought. Precession is greatest as the tail lifts to horizontal in take off.
You can feel this effect by lifting the tail of your aircraft while the motor is running. As you lift the tail, it pushes to the side.
The problem can happen when the main gear is too long. I remember reading about ground looping problems in either the ME 109 or the Spitfire. The solution: a higher tail wheel bracket: less movement of the tail to horizontal therefore less precession.
WWI planes had huge precession problems because of the rotary motors. (the mass of the gyroscope was huge). Plus, they typically had a very nose high attitude, which meant the tail had to move a lot to come to horizontal.