Can Reactionless Drive be Possible?

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Discussion Overview

The discussion centers around the feasibility of a reactionless drive, specifically exploring the concept of inertial propulsion through a rotating disc and the forces involved. Participants examine theoretical implications, potential mechanisms, and the limitations of such a device.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant proposes a mechanism involving a rotating disc and magnets, suggesting that the forces applied at different points in time could result in a net force due to the rotation.
  • Another participant argues that while spinning magnets could generate electromagnetic (EM) waves that carry momentum, this does not constitute a reactionless drive, as it relies on the momentum of the EM waves.
  • Some participants express confusion about the mechanics of force propagation from the circumference of the disc to the axle, suggesting that a diagram could clarify the concept.
  • There is a suggestion that the initial forces involved in the system may not be purely radial, indicating a potential oversight in the proposed model.
  • One participant acknowledges the theoretical nature of the idea but questions its practical application and correctness, noting that stresses and strains do not produce a net force on the system.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the validity of the proposed inertial propulsion mechanism. There are competing views regarding the feasibility of a reactionless drive, with some asserting that it contradicts established physical laws.

Contextual Notes

Participants note that the discussion involves complex interactions of forces and the propagation of effects, which may not have been fully considered in the initial proposal. Limitations in understanding the dynamics of the system are acknowledged.

Kasko32
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Is this possible?

Inertial propulsion.

If we take that nothing is faster than speed of light than we can take that reaction of force through matter can not be faster than c.

If one body act on other body by force, than other body react with same amount of force to the first body.

https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-prn1/1017601_10201279962618692_1778939648_n.jpg

Lets take that in our system second body rotate certain speed around its axis.
Example will be housing with rotating disc. Magnets will provide force. Every full circle magnets will push disc up according to housing.

https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-ash4/999308_10201279962698694_2034001389_n.jpg

Disc rotate, so force on axis will not be in same direction as forces applied in first position

https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-prn1/1009916_10201279962538690_1502604373_n.jpg

At this point we don`t have forces witch are in 180 degree opposite direction.
We have force that push down and second one that push housing up through axis in certain angle. Because of angle we have resultant force Fr applied.

https://fbcdn-sphotos-b-a.akamaihd.net/hphotos-ak-prn1/1013931_10201279962818697_1789739154_n.jpg

For example

disc rotation speed 1 000 000 rpm, which is 104 666,66 rad/s
r=10 m

we have time t1 when magnet act with force on rim of disc
we have second time t2 which is 3,34 e-8 s when force acts on axis of disc
difference between t1 and t2 is 0,003495 rad which is 0,2 degreehousing push against the disc in t1 and reaction to the axis happened at t2 time and act on housing in 0,2 degree
 
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Your links are incomplete. Please correct them.
 
Without functioning links it is not possible to tell, however a device with spinning magnets will generate EM waves and those EM waves will contain a small amount of momentum. That small amount of momentum can, in principle, propel the device. It is not reactionless, it uses the momentum of EM waves.

Of course, such a device will be horribly inefficient, like using a rocket with no nozzle and just hoping that a little more exhaust goes one way rather than the other. You will be much better off simply shining a laser off the back.

Other than the very small amount of EM momentum there will be no net force on the device. Specifically, the internal stresses and strains that you seem to think will provide propulsion will not. Any propulsion will be purely due to asymmetric radiation of EM waves.
 
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Oh I see now. You are suggesting a force applied at the circumference takes time to propagate to the axle and in that time the disc has rotated.
 
CWatters said:
Oh I see now. You are suggesting a force applied at the circumference takes time to propagate to the axle and in that time the disc has rotated.

Yes, that is idea. I see there is no practical usage, just wondering if this theory is correct.
 
Well no it can't be correct because the laws of physics say you can't build a reactionless drive. It's one of those situations where it's not obvious (at least to me) where the problem is but there will be one somewhere. The question is really is it worth spending time on it?

My thinking is that you haven't considered all the forces involved in the initial "collision" between the magnets. For example it's not obvious to me that the initial forces are radial.
 
Kasko32 said:
Yes, that is idea. I see there is no practical usage, just wondering if this theory is correct.
The stresses and strains which propagate at the speed of sound do not cause any net force on the system at any time.
 

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