Having a Thrust Machine would be very nice to have. Conventional
Wisdom says that is not possible. Yet, you probably have had the
experience with several in the past year or two.
Allow me to show you what I found.
I offer an experiment with only 3 pieces. A board (or plate), a block of wood, and a ball (sphere).
Place the board on a table so it is flat (horizontal). Drop the ball on the board.
We agree that the ball "bounces" back up.
Next, place the board on the table with the block of wood under one end of the board to form a ramp, like this one. Drop the ball on the board (now a ramp).
We agree that the ball MOVES (bounces), laterally (sideways) and down the ramp.
We agree that the cart MOVES to the right when the ball is ejected to the left.
The first 2 examples have the same input force (gravity) which causes motion of the ball. Both examples have the same ball. Both examples have the same board (to provide a reaction to the input force).
Example #1 acts like everyone expects.
Example #2 also acts like everyone expects. But shows the reaction to the board is NOT the same as in example #1.
Example #3 also acts like everyone expects.
The difference in example #1 and example #2 is the shape of the structure.
The difference in example #2 and example #3 is the lack of any new force/thing/person in example #2 causing the ejection of the ball as in example #3.
The motion of the balls ricochet off the surface of the ramp carries
most of the force from the in-coming ball from the top. The bounce
from the ramp does two things. The ball is ejected to the left, AND
the ramp has an equal force pushing it to the right. If you have
a large number of balls coming from the top, you get a continuous
movement of the ramp. Thus, uni-directional thrust to the right.
If we rearrange some of the pieces of this simple incline plane, we get closer to our desired machine. First, we turn the ramp on its side. Then we attach the ramp to an axle so that the ramp rotates around the axle. This arrangement is a Fan or propeller. Then we substitute a motor for the source of power. and finally, we substitute the air/water molecules for the balls.
Propellers are usually driven by gas motors and fans by electric motors. Either way, the force vectors are the same: the rotating propellers get their force from the axle in the vertical plane and transfer the force to the air (or water) in the horizontal plane. It is easy to only look at the air flow, but the propeller frame is experiencing a thrust in the opposite direction. This Fan Cart shows this effect. This is an example of a device that moves the ambient fluid to get a thrust.
At the pinnacle of modern engineering is the Jet Engine. This is a scaled up fan, going from ounces of thrust to hundreds of horse powers of thrust.
The important thing to notice is that other peoples thinking
out side of the box has provided us with the most powerful Thrust
Machine the world has ever known. Engineers do whatever it takes
to get the job done.
Norman Silliman, February 2012