ORIGINAL: Jim Thomerson
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AdamOne, you had a statement about both creating thrust AND accelerate the air. F=MA, where F is thrust, M is the mass of air, and A is the acceleration of the mass of air, isn't it? I don't see how you can treat thrust and accelerating air separately. I agree with your point that you can get the same, or more, thrust by using a larger disc area and accelerating a larger mass of air less.
Your observation is correct regarding thrust as a force.
The thrust produced is equal to the sum of all the lift components of the blades sections in the direction of flight.
However, as the prop rotates, there's not only an acceleration of the air in the opposite direction of the flight BUT also a rotational velocity of the air that remains in the prop wake (prop wash), which means that Thrust=MA is only the force needed to send the air straight backwards but further force is needed to give the rotational velocity to the air.
Now if we also put the prop drag in the equation, it's easy to realize that different prop types and shapes result in different thrusts for the same input power.