Question about aircraft/rockets Lets say that you're sitting an inverted airplane. How do you determine how fast the plane must accelerate in order for you to not fall out?
 A: That depends on two things: The coefficient of friction between the pilot and his seat and the direction of acceleration.
First case: The aircraft accelerates along its flight path. The pilot is pressed against the seat by the acceleration, and if that pressure is sufficient, friction will keep him in place. Since the coefficient of static friction $\mu_s$ is equivalent to the tangent of the inner frictional angle, and the ratio between gravity and acceleration is also a tangent, the acceleration $a$ along the flight path must be
$$a > g\cdot \mu_s$$ 
assuming a horizontal flight path and a vertical backrest. For different flight path and backrest angles correct accordingly.
Second case: The aircraft flies a parabola such that the pilot is pressed into his seat by centrifugal forces. If the angular velocity of the pitch motion is $q$ and the centrifugal force has to be greater than the pilot's weight, the condition is
$$q > \frac{g}{v}$$
The higher the speed $v$ you accelerate to is, the smaller the minimum pitch rate becomes.
A: The plane should travel with such an acceleration so that the weight of the force of the plane should be greater than the weight of the plane. Higher the force , the more the pilot pushed towards the seat.
