Pontoons: See Float.
Pressure nozzle: The apparatus which, in combination with a gauge, is used to measure speed through the air.
Pusher: See Airplane.
Pylon: A mast or pillar serving as a marker of a course.
Race of a propeller: See Slip stream.
Rate of climb: The vertical component of the flight speed of an aircraft—i. e., its vertical velocity with reference to the air.
Relative wind: The motion of the air with reference to a moving body. Its direction and velocity, therefore, are found by adding two vectors, one being the velocity of the air with reference to the earth, the other being equal and opposite to the velocity of the body with reference to the earth.
Right-hand engine: An engine designed to drive a right-hand tractor screw.
Righting moment: A moment which tends to restore an aircraft to its previous attitude after any rotational disturbance.
Rip cord: The rope running from the rip panel of a balloon to the basket, the pulling of which causes immediate deflation.