Author Topic: Novel mass driver for space ships thought experiment  (Read 5562 times)

Offline Iggyz

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Please see attachment.

Fig. 1. - Imagine a vacuum container (A) fitted with 2 electromagnets at each end (H, J) and two electromagnets on its sides (I), a maglev-track (B), a shuttle fitted with two electromagnets at each end (D, E) and two electromagnets on its sides (F), each holding a steel slab. The steel slabs make up 50% percent of the shuttles weight.

Fig. 2 - Next, electromagnets (with like poles facing each other are switched on. The shuttle is repelled and the container pushed to the right. Halfway, electromagnets F are switched off and at the same time electromagnets I are switched on, attracting the steel slabs. Because electromagnets I are placed opposite each other, any momentum to the top and bottom from attracting holding the steel slabs is canceled out.

Fig. 3 - Electromagnets D and J are switched on at the same time. with like poles facing each other, repelling the shuttle and the container is pushed to the left. Because electromagnets I are holding the steel slabs which constituted 50% of the shuttle's weight, the shuttle lost 50% of its kinetic energy. This allows the container to move to the right at 50% of its original speed.

Fig. 4 - On its way back the shuttle will load the steel slabs and continue to its starting position and the cycle can be restarted.

I guess this only might work if the steel slabs don't create any momentum to the left when they attract the steel slabs, pushing the container to the left. Also, does the speed of the shuttle increase when the steel slabs are unloaded? If so, its kinetic energy might not be reduced enough to allow the container to keep moving to the right.

Hopefully someone of you will explain in layman terms why this idea might or might not work.

Many thanks in advance!

Offline edzieba

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Re: Novel mass driver for space ships thought experiment
« Reply #1 on: 01/16/2021 12:04 pm »
The outer shell will simply oscillate back and forth a little, with no net velocity gain, and no change of CoM.

The core error is that nothing 'loses' KE, it is just transferred to another part of the object while retaining the same direction and magnitude.

Offline Paul451

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Re: Novel mass driver for space ships thought experiment
« Reply #2 on: 01/16/2021 01:36 pm »
In addition to edzieba's point [(paraphrasing) the iron plates carry momentum to the left, when the magnets at I capture the moving plates, they transfer that momentum to the container], I'll add that resetting the mechanism back to the right (fig.4 back to fig.1) will exactly reverse the momentum of the previous steps to the left.

Fig. 4 - On its way back the shuttle will load the steel slabs and continue to its starting position and the cycle can be restarted.

Offline Iggyz

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Re: Novel mass driver for space ships thought experiment
« Reply #3 on: 02/15/2021 06:05 pm »
Thanks edzieba and Paul451 your feedback. Sorry for the late reply. Guess you guys are right. My thought-experiment was inspired the thought-experiment David Burns used in his helical engine paper (attachment page 2).

Offline Paul451

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Re: Novel mass driver for space ships thought experiment
« Reply #4 on: 02/16/2021 12:57 am »
Thanks edzieba and Paul451 your feedback. Sorry for the late reply. Guess you guys are right. My thought-experiment was inspired the thought-experiment David Burns used in his helical engine paper (attachment page 2).

Yeah, in spite of the qualifications of the author, it's the same issue. It's just adding a relativistic component to let the author fool himself into thinking he's found a loop-hole in physics. You keep adding steps, adding complexity, until you can't see all parts of the system, so then the equation is unbalanced, et voila!, propellantless drive.

Offline Iggyz

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Re: Novel mass driver for space ships thought experiment
« Reply #5 on: 02/16/2021 06:18 pm »
Agree, but he deserves respect I think for risking his reputation and career. Funny you used loop-hole in physics'. I posted  another thought-experiment called 'the loop-hole engine' ( https://forum.nasaspaceflight.com/index.php?topic=50106.0 ) and just realized I made the same mistake twice. Guess wishful thinking is one of the strongest forces in the universe.

Offline SailorSki775

Draw a box around your vessel and all components.
Does anything leave the box (permanently)? If if does, your vessel will move in the opposite direction.
Does anything enter the box? if it does, your vessel will move in the same direction with both objects at reduced speed.
If nothing crosses the box, no net motion in Newtonian physics.

Offline Coastal Ron

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Re: Novel mass driver for space ships thought experiment
« Reply #7 on: 02/16/2021 06:32 pm »
Agree, but he deserves respect I think for risking his reputation and career.

Remember though, risking ones reputation and career does NOT change the laws of physics...  ;)
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline cdebuhr

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Re: Novel mass driver for space ships thought experiment
« Reply #8 on: 02/16/2021 07:06 pm »
Draw a box around your vessel and all components.
Does anything leave the box (permanently)? If if does, your vessel will move in the opposite direction.
Does anything enter the box? if it does, your vessel will move in the same direction with both objects at reduced speed.
If nothing crosses the box, no net motion in Newtonian physics.
Emphasis mine.  True that, but you can make an even broader statement.  The concept if forbidden by Newton, But even Einstein isn't much help here ... If memory serves, the helical drive was based on some shenanigans with special relativity, but the thing with special relativity is you've got to be very careful with your frames of reference, which is where the Helical Engine author wen't off the rails.

Offline SailorSki775

Draw a box around your vessel and all components.
Does anything leave the box (permanently)? If if does, your vessel will move in the opposite direction.
Does anything enter the box? if it does, your vessel will move in the same direction with both objects at reduced speed.
If nothing crosses the box, no net motion in Newtonian physics.
Emphasis mine.  True that, but you can make an even broader statement.  The concept if forbidden by Newton, But even Einstein isn't much help here ... If memory serves, the helical drive was based on some shenanigans with special relativity, but the thing with special relativity is you've got to be very careful with your frames of reference, which is where the Helical Engine author wen't off the rails.

And CERN scientists...easy mistake to make.  https://en.wikipedia.org/wiki/Faster-than-light_neutrino_anomaly

Offline Paul451

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Re: Novel mass driver for space ships thought experiment
« Reply #10 on: 02/17/2021 06:12 am »
And CERN scientists...easy mistake to make.  https://en.wikipedia.org/wiki/Faster-than-light_neutrino_anomaly

Nope. That was just instrument error, it had nothing to do with unbalanced physics (due to wishful thinking and making a system exactly one step more complex than the proponent can visualise.) Additionally, the CERN researchers spent six months trying to find how the result could be explained by experimental error before they gave up and published it, and made it clear that they still believed it was an anomalous result that they hoped other researchers could explain.

I'm sure they had a hope that they'd discovered truly new physics, but everything they did and said suggested they fully expected a mundane explanation.

Offline Iggyz

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Re: Novel mass driver for space ships thought experiment
« Reply #11 on: 02/17/2021 06:03 pm »
Draw a box around your vessel and all components.
Does anything leave the box (permanently)? If if does, your vessel will move in the opposite direction.
Does anything enter the box? if it does, your vessel will move in the same direction with both objects at reduced speed.
If nothing crosses the box, no net motion in Newtonian physics.

I agree with your Newtonian view, but most scientists and journalists analyzing the helical engine donít seem to question the validity of thought experiment on which the helical engine is based.

They just seem to question how the helical engine tries to achieve this, especially the dimensions of the engine and the enormous amount of energy that is needed.

The thought experiment basically says if one side of the box gets a stronger push than the opposite side of the box, there will be net thrust.

Doesnít this imply these scientists and science journalists are basically saying (at least in theory) propellantless propulsion is possible?

Offline Iggyz

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Re: Novel mass driver for space ships thought experiment
« Reply #12 on: 02/17/2021 06:08 pm »
Draw a box around your vessel and all components.
Does anything leave the box (permanently)? If if does, your vessel will move in the opposite direction.
Does anything enter the box? if it does, your vessel will move in the same direction with both objects at reduced speed.
If nothing crosses the box, no net motion in Newtonian physics.
Emphasis mine.  True that, but you can make an even broader statement.  The concept if forbidden by Newton, But even Einstein isn't much help here ... If memory serves, the helical drive was based on some shenanigans with special relativity, but the thing with special relativity is you've got to be very careful with your frames of reference, which is where the Helical Engine author wen't off the rails.

Please explain how Burns went of the rails regarding special relativity.

Offline crow_kraehe

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Re: Novel mass driver for space ships thought experiment
« Reply #13 on: 02/17/2021 11:56 pm »

Please explain how Burns went of the rails regarding special relativity.


Based on what I've read of the Helical Drive, it is simply a variant of the following design:

1. A battery supplies power to a motor which spins up the flywheel that stores this energy and thus has a
   "relativistic mass" greater than when it is not spinning.

2. We push away from the flywheel while it is spinning (more massive).

3. We decelerate the flywheel and recover its energy via wires and  recharge the battery. Its mass is back to its original, lesser value.

4. We pull the wheel back to its starting position.

Now you might think that since we pushed off of a heavy mass and pulled back on it when it was lighter that we would have produced change in our momentum. However, this is NOT the case. Notice that is step 1 we sent energy to the flywheel from the battery through the wires. This act is analogous to moving a tiny amount of mass from the battery to the motor, as mass and energy are equivalent. The same happens when we take the flywheel's energy back to the battery. Moving energy through the wires creates an impulse opposite the direction of the flow of energy, cancelling the impulse from our push-heavy, pull-light maneuver. The only way this design could work as intended (without radiating matter/energy), would be if we could "teleport" energy and matter from one end of the thruster to the other, thereby avoiding this back-reaction force.

Many people view electricity-transmission and energy transmission in general like a "teleportation-trick" so it's not hard to see how this mistake was made.

Overall you'll find that if you try to perfectly recover the energy you pump back and forth, too and from the wiggling flywheel and battery, you'll have a net 0 change in momentum no matter what design geometry you choose.

That being said, you WILL get a NONZERO net change in momentum, i.e. an impulse or "thrust" if you let the energy you sent to the flywheel in step 1 radiate away in step 3, rather than try to recover it. However, this would be nothing more than a convoluted photon rocket, as photon rockets radiate energy as photons which impart momentum to the thruster like any old rocket engine does.

The Helical drive is nothing more that a fancy version of the above scenario, making it difficult to see this flaw with its design.
« Last Edit: 02/18/2021 12:10 am by crow_kraehe »

Offline Alex_O

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Re: Novel mass driver for space ships thought experiment
« Reply #14 on: 02/19/2021 04:12 pm »
Now you might think that since we pushed off of a heavy mass and pulled back on it when it was lighter that we would have produced change in our momentum. However, this is NOT the case. Notice that is step 1 we sent energy to the flywheel from the battery through the wires.[/size]

Hi!
And if there are no wires? You have a wheel-motor.




The accumulator is installed in the center of rotation of the wheel (in the stator). And the flywheel is the rim of the wheel, in zero gravity this thing will rotate (the rim in one direction, the stator in the other). When braking, you will have a wheel generator and the energy will return to the battery.

Offline crow_kraehe

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Re: Novel mass driver for space ships thought experiment
« Reply #15 on: 02/19/2021 04:14 pm »
How do you intend to generate thrust from a flywheel that you neither push or pull on? @Alex_O

It is well known that satellites change their angular momentum will flywheels, but this alone does not constitute a method of propulsion.

Edit: On second glance I think I may have misinterpreted the motivation for your post, in that I think you intended to affirm what I said before rather than object to it. Correct me if I'm wrong, though.
« Last Edit: 02/19/2021 04:19 pm by crow_kraehe »

Offline Alex_O

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Re: Novel mass driver for space ships thought experiment
« Reply #16 on: 02/19/2021 05:24 pm »
How do you intend to generate thrust from a flywheel that you neither push or pull on? @Alex_O

It is well known that satellites change their angular momentum will flywheels, but this alone does not constitute a method of propulsion.

Edit: On second glance I think I may have misinterpreted the motivation for your post, in that I think you intended to affirm what I said before rather than object to it. Correct me if I'm wrong, though.

I divided the problem into 2 parts
1. motor-wheel with battery and computer - I removed the wires.
2. The captain of the boat can throw this motor-wheel into the stern of the boat (like a weight) - when the motor is turned on (and its inertia (mass) is greater).
3. And return the motor-wheel back when the motor is off.

It seems like there should be a thrust. There are no wires, but there is a controller with a recorded program for turning the motor on and off, this is something new, it can somehow be important.

Offline crow_kraehe

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Re: Novel mass driver for space ships thought experiment
« Reply #17 on: 02/20/2021 12:19 am »

I divided the problem into 2 parts
1. motor-wheel with battery and computer - I removed the wires.
2. The captain of the boat can throw this motor-wheel into the stern of the boat (like a weight) - when the motor is turned on (and its inertia (mass) is greater).
3. And return the motor-wheel back when the motor is off.

It seems like there should be a thrust. There are no wires, but there is a controller with a recorded program for turning the motor on and off, this is something new, it can somehow be important.

You forgot that the battery inside the wheel-motor-battery assembly contains the energy when it is not stored in the flywheel, meaning that the mass of the wheel-motor-battery assembly remains constant throughout your process.

Offline Alex_O

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Re: Novel mass driver for space ships thought experiment
« Reply #18 on: 02/20/2021 03:38 am »

I divided the problem into 2 parts
1. motor-wheel with battery and computer - I removed the wires.
2. The captain of the boat can throw this motor-wheel into the stern of the boat (like a weight) - when the motor is turned on (and its inertia (mass) is greater).
3. And return the motor-wheel back when the motor is off.

It seems like there should be a thrust. There are no wires, but there is a controller with a recorded program for turning the motor on and off, this is something new, it can somehow be important.

You forgot that the battery inside the wheel-motor-battery assembly contains the energy when it is not stored in the flywheel, meaning that the mass of the wheel-motor-battery assembly remains constant throughout your process.
No, I haven't forgotten. Everything will work if in the near zone of the flywheel a new physics somehow appears, so that the inertial mass of the flywheel will differ from the gravitational one.
« Last Edit: 02/20/2021 03:55 am by Alex_O »

 

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