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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
(If you feel this article is to long you can view a quick summery in this Prezi presentation)
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.
Originally Posted by wjeconsultant
