# Thread: Proposal for a propellantless propulsion using fluids

1. Proposal for a propellantless propulsion using fluids

To propose a method of space propulsion that does not expel mass is considered a fool’s errant by many (specially in the physics forum), yet I present here a very simple and easy to test propellantless propulsion method using fluids.

More important I present the experiments that support the idea

We were all taught that accelerating a closed system (spacecraft) without expelling mass/propellant is impossible, we were presented with many examples involving springs, levels, movement of mass or masses.

Most of the examples were graphically represented in ideal situations in airless environments, because of that state of mind we neglected to conceder simpler methods.

How It Works
(Accelerating a mass inside a structure without transferring all the momentum to the structure)

FIG 1 shows a pressurized structure(M1) (spacecraft) in orbit at approximately 28000 kph, inside the structure is a 100k mass that is also traveling at 28000 kph so to an external observer the mass(M2) is “floating” inside the structure.

image001.png
FIG 1

If we increment the velocity of M2 (100k) in the +X direction by 1 mps (meters/seconds), M2 will collide with the spacecraft’s “forward” (or +X hull) at 1 mps creating a force of 100 newtons, but with every method we may use to increment mass M2’s relative velocity by 1 mps an equal 100 newton force will be created in the –X direction making useful propulsion impossible (fig 2)
image003.jpg
Fig 2

We can accelerate the 100k mass to 1 mps by various means but…

Method 1; pushing with a spring, method 2; pushing with a mechanical arm, method 3; acceleration by expelling a steel ball, method 4; acceleration by expelling a series of steel balls or other means (see) BUT no matter what we try (rubber bands, springs, steel balls, grasshoppers, anything) the spacecraft will not gain velocity (it may oscillate but not accelerate).
image005.jpg
Fig 3

Note: The length or shape of the spacecraft has no effect on the end result, for instant, using method 1, when the spring is pushing mass (M2) a 100N force is exerted on the spacecraft in the –X direction.
The instant M2 collides with the forward hull, a 100N force is exerted in the +X canceling any change in velocity of the system.

Method 5: Acceleration by expelling air by propellers or air blower.

NOW I learn I can only attach 3 images per post (fair enough, will provide link)

Fig 4 See: See: Proposal fig 4

Illustrated in fig 4 we see the 100k mass (M2) accelerating in the +X direction pushed by a propeller, gaining momentum and kinetic energy.
Let us say that the propeller must be turned on for 5 seconds to increment M2’s relative velocity by 1 m/s (meters/second).

The BIG question is, will the resulting force F2 in the –X direction always be equal to F1?

Fig 5 See: Proposal fig 5

1) First let us again consider the forces exerted in the +X (forward) direction if we turn on the propellers for 5 seconds at different positions inside the spaceship.

The initial position of mass M1 may be almost touching the rear end of the spaceship (A) or very near the forward end of the spaceship (B) if it is accelerated by 1m/s, when it finally collides with the forward (+X) hull it will exert the same 100n force if it coasted for 1 second or one hour (very long spaceship).

We will all agree that if mass M2 has a relative velocity of 1m/s the instant of collision against the inner +X wall (fig 6), it will exert the same force in the +X direction regardless of method used to accelerate the mass (rubber bands, springs, steel balls, grasshoppers, anything. Fig 3)

If the final velocity of mass M2 is equal, the resulting force in the +X direction is not affected by M2’s original position, distance it has traveled nor length or shape of the spaceship.

2) Let us now consider the forces exerted in the -X direction if we turn on the propellers for 5 seconds at different positions inside the spaceship.

Fig 6 See: Proposal fig 6

The force exerted by an expelled gas on a target is not the same regardless of distance, as the air molecules traveling on their way to the –X surface will collide with the billion and billion of fast moving air molecules, this may seem logical to many but as we have the paradigm that a closed system (spaceship) cannot be accelerated without expelling mass, the resulting forces in the –X direction must be the same regardless if the propeller is 1 millimeter from the –X inner wall or 1 kilometer form the –X wall (for the paradigm to be true).

Question, why expect gas to behave different than say method 4 (fig 2), isn’t accelerating mass M2 by expelling gas molecules (when hit by the propeller’s blades) equivalent to acceleration by expelling millions of tiny steel balls?

Answer: If the method used to accelerate M2 is expelling a steel ball (or millions of tiny steel balls), as steel is a mass of bound molecules it travels to the –X wall unmolested by the billions of air molecules that it encounters on the way to the –X hull (Fig 7) and all the steel ball’s molecules collide with the –X hull (Fig 8) balancing the force put forth by M2 when it collides with the +X hull (Fig 8).

And what about Newton’s third law? (see Note 1)

Fig 7 See: Proposal fig 7

Fig 8 See: Proposal fig 8

If the method used to accelerate M2 is a propeller (or other method) that hurls air molecules in the –X direction, the molecules cannot arrive at the –X side (hull) of the container uninterrupted, they are constantly colliding and being diverted by moving air molecules, the longer the traveling distance, more particles will collide and be deflected becoming more random with regards to the X axis (Fig 9).

Total momentum is not lost, but the individual molecules vector size and direction change, becoming as random as the other gas particles.

Fig 9 See: Proposal fig 9

You may say that the idea must be wrong because it conflicts with 300 years of science, what we read in books (and Wikipedia too), it is time to experiment.

If the idea/principle/method/law disagrees with the experiment it’s wrong, that all there is to it (Richard Feynman describing what science is).

Please continue to Part II were the feasibility and efficiency of the Fluid Space Drive configuration is tested with a simple dynamic test rig.

2.

3. I don't have time to read all this, so I'm just going to go with the LAW of conservation of momentum. It's Pseudoscience.

4. Harold14370, your intuition is correct. Total momentum is always conserved - this is a result of Noether's Theorem, and can be shown in the general case for all systems.

5. Dear Harold14370

You are right, your time is valuable, that is why the concept is illustrated in a short Prezi: FSD. by william elliott on Prezi

If everybody refuses to examine new ideas because it appears far out, the list of things we would be missing today would include heaver tan air travel and spaceflight.

By the way academics that have kindly spent time looking at my proposal agree that it works. (U of Chile science department)

So come on, take a look, only a few slides (you might see something interesting)

6. Originally Posted by wjeconsultant
By the way academics that have kindly spent time looking at my proposal agree that it works. (U of Chile science department)
You do realise that one way of dealing with calls from crackpots is tell them they are right; after all arguing with them is pointless.

Talking of which, of course you are quite right. You have a revolutionary idea which has obviously been suppressed by NASA for decades.

7. I looked. It's pseudo.

8. Thanks for looking but..

Could you type a few words of why it’s pseudo?

9. Originally Posted by wjeconsultant
Thanks for looking but..

Could you type a few words of why it’s pseudo?
It violates several fundamental laws of physics, most notably of course the law of conservation of momentum. Also, not sure if you are aware of this, but this has all been done and proposed before. Notable example are :

Dean drive - Wikipedia, the free encyclopedia
EmDrive - Wikipedia, the free encyclopedia

both of which have been shown to not actually work, because they were in violation of basic physical laws.

10. The nice thing about the conservation of momentum and energy principles is that you can skip right over the experimental flaws, math errors, logical fallacies, word salad, etc. and conclude right away "this can't work." This is what I did earlier.

Now that I had a little more time, I took a look at the video and it puts a lot of stock in some experiments where a vehicle is placed in an enclosure mounted on a rotating platform, where it is propelled by a fan in the enclosure and run back and forth slamming into the wall of the enclosure. The platform slowly ratchets around in a circle.

The flaw in this experimental design is that the rotating platform is not isolated from the outside world. It is supported on some sort of bearing which communicates with the floor via friction. The obvious way it can move around is the difference between static friction and sliding friction. As the vehicle comes up to speed, it does not produce enough torque to overcome the static friction. This allows the vehicle to accelerate without having the platform accelerate in the opposite direction. When the vehicle slams into the wall of the enclosure, there is enough force to overcome the friction and the platform ratchets around.

11. Thanks for “putting a little more time” (most people don’t)

The rotating platform is NOT supported by bearings on the floor; it is suspended from the ceiling:
http://www.wjetech.cl/part1.htm figs 16 and 17.

This was done so that no there is no static friction vs. sliding friction present if you try to test on the floor even if suspended on dry ice plucks (works well when tried)

12. They had to listen to me, my son is a pre-grad.
And since you're paying them money, they'll say whatever you want to hear.

13. Originally Posted by wjeconsultant
Thanks for “putting a little more time” (most people don’t)

The rotating platform is NOT supported by bearings on the floor; it is suspended from the ceiling:
Effect of Momentum Dismemberment on Linear Momentum.

This was done so that no there is no static friction vs. sliding friction present if you try to test on the floor even if suspended on dry ice plucks (works well when tried)
Still the same problem, the platform is not isolated. Instead of bearings you now have strings, which again provide a mechanism for momentum conservation.
Why can you not accept that it can be shown to be impossible to violate the conservation of momentum, in the general case ?

14. Originally Posted by wjeconsultant
Thanks for “putting a little more time” (most people don’t)

The rotating platform is NOT supported by bearings on the floor; it is suspended from the ceiling:
Effect of Momentum Dismemberment on Linear Momentum.

This was done so that no there is no static friction vs. sliding friction present if you try to test on the floor even if suspended on dry ice plucks (works well when tried)
Are you sure the enclosure is air tight?

15. Duct tape, lots of duct tape.

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