Mechanical propulsion

[trekkie_]

It works by essentially extending to a new point in space, then retracting from the old point, and so on and so forth. The spheres house the motor that either; slides it along the sides on a track, or rotates everything else in relation to it. This is just a simplistic concept design to give a general idea, but some designs could possibly offer a much higher rate of speed. Even if you only got a meter a second out of it (which would depend on size, speed, and stability of the design) that would be enough to mechanically alter orbit altitude over time. It would operate purely on electricity.

For example, if you were able to create a 1 m/s speed, it would take approx. 16 minutes to raise or lower orbit by 1km. Even much slower speeds could produce meaningful results over time.

Obviously, it's not practical for long distance travel, but for something you want to keep in orbit for a long time without worry of running out of fuel, and possibly at a very cheap production cost, or put them in a lower orbit and have them work their way into a higher orbit over time.

It seems like something worthwhile, especially for small and micro satellites. Unless of course I'm neglecting some fundamental principle.

Edited March 15, 2014 by trekkie_

[kahlzun]

Conservation of momentum: every time it 'extended to a new point in space', it would push the satellite in the other direction, which would be undone as soon as you restored it to its original state.

Unless the spheres somehow 'grab hold' of space around them, it's like using a yoyo, you have to pull on it to get the weight back

[trekkie_]

Conservation of momentum: every time it 'extended to a new point in space', it would push the satellite in the other direction, which would be undone as soon as you restored it to its original state.

Unless the spheres somehow 'grab hold' of space around them, it's like using a yoyo, you have to pull on it to get the weight back

what if say, there was a transfer of mass from one sphere to the other?

I'm not visualizing how it would push the sat in the other direction.

for example, let's say this crude ascii represents the actions it takes, the 2 dots represent the positions of the spheres:

state1:

.|.

state2:

.|'

state 3:

'|'

now obviously, the right sphere in state2, is now occupying a new point in space 'above' the original point, it is undoubtedly slightly further from the earth. so by retracting the rest of the apparatus toward it, it seems like it would alter its point in space, even if only by small margins.

Edited March 15, 2014 by trekkie_

[Bacterius]

Ah, is it perpetual motion month already?

[trekkie_]

Ah, is it perpetual motion month already?

this isn't really about perpetual motion, it's about changing an objects point in space without propellants, and only through mechanical motion. don't picture it as some kind of spinning thing hurling through space, but rather more like a robotic arm methodically moving in a ladder climbing motion.

Edited March 15, 2014 by trekkie_

[shynung]

Ah, is it perpetual motion month already?

this isn't really about perpetual motion, it's about changing an objects point in space without propulsion, and only through mechanical motion. don't picture it as some kind of spinning thing hurling through space, but rather more like a robotic arm methodically moving.

No, he's right. In order to move using the OP's principles, the balls have to 'grab' something in space. Spacecrafts in orbit have practically nothing to grab on to, so they have to produce thrust via expelling reaction mass.

Edited March 15, 2014 by shynung

[andrewas]

for example, let's say this crude ascii represents the actions it takes, the 2 dots represent the positions of the spheres:

state1:

.|.

state2:

.|'

state 3:

'|'

OK, that works, the body of the craft has now moved from where it started. Now, get from state 3 to state 1 without cancelling that movement.

[CalculusWarrior]

While you can do this in KSP (Scott Manley did a video of it) by pumping fuel between the ends, such a contraption you are describing is impossible. I imagine such a device in action would look a lot like a cartoon character who has just realized he/she is standing in midair after running off a cliff. While they may try running as fast as they can back to solid ground, their legs have nothing to push on and they fall to the ground.

[trekkie_]

OK, that works, the body of the craft has now moved from where it started. Now, get from state 3 to state 1 without cancelling that movement.

state1:

.|.

state2:

.|'

state 3:

'|'

state4:

.|.

see, in state 1, 2, and 3, only one sphere is moving at a time along the track, but in state 4, both spheres rotate the central plank 'upward' relative to their position.

the movements in state 2 and 3 are both a counter clockwise spin on a gear connected to the track, but state 4 is a clockwise spin.

or the central plank itself can fold in half and rotate, essentially going from state 4 to state 1, but occupying a slightly higher elevation.

Edited March 15, 2014 by trekkie_

[Stargate525]

Ignore the balls for a moment. Focus on the center of mass. It's not going anywhere. You're sliding the device back and forth around it. If the rod is a meter long, and the closest edge is 1000m above the surface in stage 1, stage 2 moves the rod about half a meter downward, stage three moves it another half meter, so that when you rotate it around it's back to 1000m above the surface.

[trekkie_]

While you can do this in KSP (Scott Manley did a video of it) by pumping fuel between the ends, such a contraption you are describing is impossible. I imagine such a device in action would look a lot like a cartoon character who has just realized he/she is standing in midair after running off a cliff. While they may try running as fast as they can back to solid ground, their legs have nothing to push on and they fall to the ground.

well here's an easier way to visualize it. say a space shuttle attached to a robot arm was holding an astronaut, and extended them out as far as it would go.....now think of what it would take to allow that astronaut to be able to grab and rotate the space shuttle by holding the arm.

if it's something as simple as mass, then mass could be fed into one sphere at a time, through say a dense liquid, then drained and alternated between movements. then you will have the larger mass object, pulling on the lower mass object.

[trekkie_]

Ignore the balls for a moment. Focus on the center of mass. It's not going anywhere. You're sliding the device back and forth around it. If the rod is a meter long, and the closest edge is 1000m above the surface in stage 1, stage 2 moves the rod about half a meter downward, stage three moves it another half meter, so that when you rotate it around it's back to 1000m above the surface.

no I get what you're saying, that the 'track' is essentially staying in the same position, but the sphere's are just sliding up and down it not going anywhere. but is that really what's happening? especially if say, the central track weighed less than the spheres themselves?

I mean if you look at it, I think the key is in that only one sphere is moving at a time until they're both at the 'top' then they both move at the same time, effectively pulling the central plank up relative to their new position in space. it doesn't have to be pulled either, the spheres in state4 could rotate the whole plank together instead of sliding along the tracks.

Edited March 15, 2014 by trekkie_

[Climberfx]

I already did some experiments on child with this principle. In that time, i put an stuck on floor and a bike wheel with another stuck rolling on it in horizontal, and it moves circular and don't fall. (The Wheel is above ground, not touching it)

Is amazing the work. But i can tell, it need gravity on the floor to work.

In space, you don't have a fix point to make the work go in that direction. So it will roll in axis, not move.

Follows a draw of my experiment...

Edited March 15, 2014 by Climberfx

[trekkie_]

well I think it goes back to this: when you rotate a robotic arm attached to a space shuttle.....why does the arm rotate and not the space ship? and the obvious answer is: mass. but with the spheres, the center and bulk of the mass gets shifted. imagine say the spheres weighed 10lbs each and the track was just a 1lb frame with a foam covering. you should be able to move the track relative to the sphere's positions, rather than the spheres relative to the tracks position.

[Rakaydos]

well I think it goes back to this: when you rotate a robotic arm attached to a space shuttle.....why does the arm rotate and not the space ship? and the obvious answer is: mass. but with the spheres, the center and bulk of the mass gets shifted. imagine say the spheres weighed 10lbs each and the track was just a 1lb frame with a foam covering. you should be able to move the track relative to the sphere's positions, rather than the spheres relative to the tracks position.

Just to note, the ship DOES move when the arm moves. The center of mass of the arm+ship remains completel stationary, because the arm is pushing off the ship.

Same with this device. It doesnt matter what you do with the balls, the center of mass isnt moving an inch.

Edited March 15, 2014 by Rakaydos

[trekkie_]

Just to note, the ship DOES move when the arm moves. The center of mass of the arm+ship remains completel stationary, because the arm is pushing off the ship.

yes, but the movement of my object, alters the center of mass. you have to consider that the spheres and central plank/track aren't equal mass. if say the space shuttle arm grabbed onto something that weighed much more than the spacecraft, then rotated the arm, the space craft would be rotating but not the object (or at least, not in any meaningful sense). if the arm tugged at the object, the craft would be pulled toward the object, rather than the object being pulled toward it.

Edited March 15, 2014 by trekkie_

[Brotoro]

When your device moves a ball, it has to push on it. The ball pushes back (Newton's Third Law) and so the body of the device moves the other direction. The center of mass of the system does not change when you have nothing external to push against. The same thing happens when you pump your dense fluid around… The fluid will not move unless the pump pushes it, and that results in the fluid pushing back on the pump. The center of mass of your object will not change either way…you are just changing the locations of the parts with respect to the center of mass.

[CalculusWarrior]

well here's an easier way to visualize it. say a space shuttle attached to a robot arm was holding an astronaut, and extended them out as far as it would go.....now think of what it would take to allow that astronaut to be able to grab and rotate the space shuttle by holding the arm.

if it's something as simple as mass, then mass could be fed into one sphere at a time, through say a dense liquid, then drained and alternated between movements. then you will have the larger mass object, pulling on the lower mass object.

This is the fundamental point. Pumping mass around (or moving those balls in that device) does change the position of the object, but not in the way you might think. If you pump mass forward, your rear will move backward. It is simply conservation of energy at its finest.

You cannot get energy out of a closed system without interacting with the rest of the universe (while I would very much enjoy if we could break that law, the Second Law of Thermodynamics is set in stone).

So I shall demonstrate what would happen to your object, using the same ASCII art you did. (I'm lengthening the rod to illustrate the point better, and the x's are there to show where the rod is in space)

State 1: Initial position
x  |
x .|.
x

State 2: We've moved both balls backwards along the rod. Note how it looks like we moved the rod forward? This is because we have not altered the total mass of the system at all.
x
x .|.
x  |

State 3: We now move the balls forward to try and change our external momentum.
x  |
x .|.
x 

Whoops! The rod moved back! This is because we have nothing to push off of.

Again, the Second Law of Thermodynamics rears its head. If we were to get something to push off of (like attach a rocket motor to the rear end of it to keep it in place while we're moving the balls), this would stop our system from being reactionless.

So to finish off, I shall paraphrase an old quote:

If you have discovered something which disagrees with Einstein, then I am excited to hear what it is. But if you have discovered something which disagrees with the Second Law of Thermodynamics, then you are wrong.

[Sillychris]

I'm going to join the physics informed commenters in this thread and point out:

a) Conservation of momentum (grade 11 physics).

The center of mass isn't going anywhere (This is more 1st year university physics, but still pretty straightforward).

Silly commoners always thinking they've discovered a simple way to ignore the laws of physics.

[Rakaydos]

Out of curiosity, can the physics-inclined explain the difference between this and the Woodward_effect?

[Nibb31]

or the central plank itself can fold in half and rotate, essentially going from state 4 to state 1, but occupying a slightly higher elevation.

No. When you go back to state 4, you move the CoM of your contraption exactly back to where it was in state 1. You have not moved.

If this was possible, you could move a train just by transferring mass from the first wagon to the last wagon and back again. Or you could get a satellite to change orbits by successively folding and unfolding its solar panels. However, real-life doesn't work that way.

Besides, NASA stopped using the "worm" logo more than 20 years ago.

Edited March 15, 2014 by Nibb31

[trekkie_]

Out of curiosity, can the physics-inclined explain the difference between this and the Woodward_effect?

that's a good question, but I think that's quite a bit more complex than this.

Edited March 15, 2014 by trekkie_

[Stargate525]

but is that really what's happening?

Yes. Yes it is.

[CalculusWarrior]

Out of curiosity, can the physics-inclined explain the difference between this and the Woodward_effect?

The Woodward Effect is essentially an evolved version of this thought experiment, one which would (theoretically) work.

Unfortunately, there has not been sufficient proof to even confirm the Woodward Effect's existence, so it doesn't look like we're getting reactionless spacecraft anytime soon...

[Sillychris]

Out of curiosity, can the physics-inclined explain the difference between this and the Woodward_effect?

It looks to me like the Woodward effect attempts to harness some weird fluctuating relativistic effects. The OP's design relies simply upon classical physics.

Also, in the wikipedia article, it blatantly states that harnessing the woodward effect would not be possible with a mechanical system. What the OP suggested was a mechanical system. There's your second difference.