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Explaining the Fluid Drive V3 with two astronauts and a steel ball (previously three kids, an umbrella, a skateboard and batman)


Tongue in cheek explanation of how the Fluid Drive proposal works using a spaceship, astronauts and Batman (Adam West version)


In fig 1 we have a spaceship in orbit, inside are two astronauts (A and B) and a steel ball.

Fig 1

Astronaut A and astronaut B are at the forward and rear end of the spacecraft, if astronaut B pushes the steel ball at astronaut A with force F1 (red arrow) he will receive a counter force F2 (blue arrow) that will be transferred to the spacecraft



Fig 2

As the steel ball travels towards astronaut A with velocity V2 (fig 2) the spaceship is traveling in the +X direction at velocity V1.



Fig 3



The steel ball collides with astronaut A (no doubt he feels the force that is transferred to the spaceship) as their momentums are equal (momentum = velocity x mass) system (spaceship and all inside) returns to original velocity 0.



Fig 4

If astronaut A pushes the steel ball back at astronaut B, when the ball collides with astronaut B the result will be the same (the spaceships velocity returns to 0), they can play all day but all the spaceship will do is wobble.


What happens if an air brake is activates when the steel ball is traveling from B to A?


Astronaut B pushes the steel ball (with umbrella still closed EXACTLY as fig 1), kid C gains V2 and box gains velocity V1.






Fig 5

When speeding towards astronaut A, the steel ball activates an air brake (fig 5) that increases drag reducing its velocity form V2 to V3i, the spacecrafts V1 velocity is not affected (not very much).



Fig 6


When the steel ball collides with astronaut A, the spaceship’s momentum P1 is almost identical to instant illustrated in fig 3, but as the steel ball’s velocity has decreased from V3i to V3f its momentum p3 is less than momentum p1 and the force excreted by the steel ball on astronaut A (and the spaceship) is not sufficient to return the spaceship’s original velocity therefore it will gain velocity in the +X direction.


Astronaut A can return the steel ball to astronaut B with a very slight push (it does not matter that it takes longer to travel the length of the spaceship) so astronaut B repeats this cycle and the spaceship will gain velocity with every cycle.


A step by step explanation of the principles involved (for the serious minded, no kids, no skateboard, no batman, no puns


The batman postulation


Chris from Brock U. had the following comment: Would the application of the air brake (fig 9 B) not create air movement similar to that created by a propeller (fig 9 B)?


Fig 9


I think not, picture yourself as batman (Adam West incarnation) trapped in a box with a wheeled cart speeding towards him.


If the speeding cart is slowed and stopped by a propeller (fig 9 B) you (you’re batman remember) WILL feel a strong breeze to say the least but if the speeding cart is slowed and stopped by a parachute (like a drag racing car) you will not feel the same “breeze”


A DIY test


This idea can be tested (or disproved) with a very simple test setup.


Fig 13


We need a box on a near frictionless surface, inside the box a test car and a mechanism (in this example a compressed spring)


Fig 14


When the spring is released the box (M1) will gain a velocity (V1) in the +X direction and the car will gain a velocity (V2) in the –X direction.



Fig 15


As they travel in opposite directions their velocities (V1 and V2) remain approximately constant.




Fig 16


When the car collides with the box’s inner wall, it’s momentum (mass X velocity) will be sufficient to stop the box that will return to its original velocity 0.


This test must be repeated various times

If the box final velocity is different from 0 (however slightly) it means the test bed is flawed and the resulting velocity must be subtracted from any results obtained.




Fig 17

We can now repeat the experiment with an air brake attached to the test car.




Fig 18

When the spring is released the box (M1) will gain a velocity (V1) in the +X direction and the car will gain a velocity (V2) in the –X direction.




Fig 19


Fig 20

As the test car moves in the –X direction (Figs 19and 20) the addition of the air brake will (should) decreases it’s velocity (V2i > V2a > V2b > V2f)



Fig 21


When the test car collides with the box, if the drag produced by the air brake on the test car does not affect the box, then the test car’s momentum (V2f x cars mass) will have decreased while the box’s momentum will have remained the same therefore the box should have a noticeable +X final velocity


This has been a Tongue-in-cheek description of the idea, the serious minded please see step by step (no kids, no skateboard, no batman, no puns)


How it would work in space




the main elements of a Fluid Space Drive v2 are a pressurized structure (2), inside we have a mass we call Ram Mass Assembly (RMA) that can move across the length (not breadth) of the structure, its position is controlled by two winches (forward and rear) that connect to the RMA by guiding cables.

By ether pulling or reliceng cable form either side the RMA can be propelled back or forward across the length of the structure.


The propulsion cycle




Cycle 0

The RMA is “parked” at the forward inner end of the pressured structure, maintained in position by the forward cable that is keep tense by the forward winch.

The rear cable is also kept tense by the rear winch.




Cycle 1

The RMS’s flaps rotate to closed position.

The forward winch reliseas cable making it slack

The cable between the winch and the tensing rollers are always maintained tightly stretched so as to avoid cable enchantment

The rear winch tenses the rear cable pulling the RMA with force F2 giving it an acceleration A2 in the –X direction, the opposite force F1 accelerates the pressurized structure (and the spacecraft attaches to it) in the +X direction.



Cycle 2

The pressurized structure moves in the +X direction at velocity V1

The rear winch stops pulling the rear cable, the RMA moves from initial position p1 to final position pf without being tugged either by the forward or rear winch.

The forward winch continues to release cable maintaining it slack

The rear winch pulls cable only to prevent entanglement, not sufficient to pull the RMA.

As the RMA moves from initial position p1 to final position pf with it’s flaps in closed position, the drag on the RMA slows its relative –X velocity form V2i to V2f.

The pressurized structure’s V1 velocity is not greatly affected.




Cycle 3

The RMA’s flaps are position to open (permit air flow)

The rear winch stops tensing the forward cable between the RMA and the rear winch.

The tensing of the cable exerts a force (F3) on the RMA stopping its –X displacement (and gaining a slight +x velocity as a “bounce” effect)

The pressured structure receives an opposite force (F4) as a pull by the rear cable.

As the RMA’s –X velocity has decreased because of drag it has lost momentum (P + M x V) while the pressurized structure’s velocity (V1) has remained mostly unchanged, there force F4 is not equivalent to V2 and the pressurized structure retains a portion of it’s +X acceleration every cycle



Cycle 4

The pressurized structure continues in the +X direction with velocity V4

The RMA travels in the +X direction, as the flaps are open (no drag) it travels at a constant velocity (V5)

The rear winch releases cable maintaining it slack so no force is exerted on the RMA

The forward winch pulls just sufficient cable in so as to prevent entanglement.




Cycle 5 (now cycle 1)

The RMA’s flaps close

The forward winch relaxes cable making it slack

The rear winch gives the rear cable a strong pull, this exerts a force (F4) on the RMS that will stop it’s +X velocity and accelerate it in the –X direction the opposite force F5 accelerates the pressurized structure (and the spacecraft attaches to it) in the +X direction.


Continue/return to cycle 2


See description of this effect for propulsion here.



Fig 7


Main Page, Other versions, testing the principle, testing version 2


(This document is a work in progress)