Steve:

Sorry, as I said in my earlier post I was trying to figure another way to re-word it. Basically, p-factor is an effect of air entering the prop disc at an angle to the axis of the propellor. Greater angle greater effect, lesser angle lesser effect.

But on gyroscopic precession, there are no precessive forces until the axis of the gyroscope is disturbed. So there are none on a straight take-off roll until the tail rises, and then only as the tail rises. With a new equilibrium, i.e. accelerating with the tail up the precessive force disappears once again, until the nose is pulled up breaking ground. And yes, the amount of the precessive force is dependent on the rate of change.

Further, the rotating mass (prop and engine internals) is such a small percentage of the total airframe weight precessive forces are usually ignored anyway.

Now if you go back to the WW I planes with the leRhone, Gnome, Bentley, Oberussel, and other rotary engines precession is a large consideration, many pilots were killed by forgetting about the big gyroscope they had on the nose. If one wanted to turn right at low altitude, for example, he hauled back on the stick. If he gave a lot of right rudder input he found his engine would stop when it hit the ground. Even this was different from one rotary engined plane to the next, as reversing the engine rotation also reversed the effect.

Hope this helps clear things up. If not, yell at me, make me explain things more clearly.

Bill.