Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1797946 times)

Offline TheTraveller

You do understand that for a truly static EMDrive it will NOT move?

Shawyer in his Force measurement document makes that very clear.

The EMDrive operates in 1 of 3 mode:

1) Do Nothing - no externally applied forces

2) Motor Mode - externally applied force moving the cavity big end toward small end.

3) Generator Mode - externally applied force trying to move the cavity small end toward big end.

The Energy for the Motor Mode generated Force to do Work over Distance comes from newly created microwave energy, powered by increased energy draw on the power supply.

Hook an EMDrive to a rotary wheel and feed it to a generator is not a source of free energy as the energy necessary to turn the generator under load comes from the EMDrives primary electrical power supply.

Pardon me if I am not understanding but I would like to clarify what seems to be a conceptual problem.  Are you saying an em drive can be truly static?  That doesn't make sense to me because take a car for instance moving down the street.  The EM drive is not static to the car.  In the case of the car the EM drive can do work and has force but for the lab frame observer no force is observed?  In one case the Em drive could gain kinetic energy and the other frame would observe no gain in kinetic energy.  That just doesn't seem right to me or am I misunderstanding things.

With no externally applied forces, the EMDrive will not generate force to support movement nor generate a force to oppose accekeration.

Please read these 2 documents.

Understanding this comment is very important

Quote
A  number of  methods  have  been  used  in  the  UK,  the  US  and  China  to  measure  the forces  produced  by  an  EmDrive  thruster. In  each  successful  case,  the  EmDrive  force data  has  been  superimposed  on  an  increasing  or decreasing  background  force, generated by the test equipment itself. Indeed,  in  the  UK  when  the  background  force  changes were  eliminated,  in  an  effort to  improve  force  measurement  resolution,  no  EmDrive  force  was  measured.  This was clearly  a  result of  attempting  to  measure  the  forces  on  a  fully  static thruster, where T and R cancel each other.  UK  flight  thruster measurements  employ  this  principle  to  calibrate  the  background noise on the force balance prior to carrying out force measurements.

Have attached pages 6 & 7 of the basic theory presentation to explain the 3 modes of operation
« Last Edit: 06/24/2015 03:06 AM by TheTraveller »
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Offline Prunesquallor

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You do understand that for a truly static EMDrive it will NOT move?

Shawyer in his Force measurement document makes that very clear.

The EMDrive operates in 1 of 3 mode:

1) Do Nothing - no externally applied forces

2) Motor Mode - externally applied force moving the cavity big end toward small end.

3) Generator Mode - externally applied force trying to move the cavity small end toward big end.


So I always had trouble understanding this. Take "Motor Mode". Suppose the EMDrive has an externally applied force, say applied horizontally toward the small end that would accelerate the EMDrive at 1 g. When does the EMDrive start thrusting?  As soon as the velocity is greater than zero?  How does it "know" when that happens?
Retired, yet... not

Offline zero123

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The only place where I know that Shawyer has specifically addressed spaceship transit times is last month's Daily Mail article: "Its inventor calculates that an interstellar probe would take ten years to reach two-thirds the speed of light, which he sees as pretty much the limit of how fast we could practically travel."  I analyzed that claim here (over on the Feature Article thread) and showed that with T/P < 1/v specific thrust limitation his zero to 2/3 c in 10 years craft would require a power plant which generates at least 97.3 MW/kg.  That is a massive power density and is five orders of magnitude greater than the astounding 1 kW/kg which VASIMR needs for its 39 day trips to Mars.

It is also possible that Shawyer simply forgot to apply his T/P < 1/v when he calculated his interstellar probe acceleration.

These figures for the interstellar probe can be seen in this presentation of Shawyer's: http://www.emdrive.com/iac2014presentation.pdf, specifically slides 9 and 10. He says 304 N/KW and 1m/s^2 and it looks like he means these to be constant. He also says that his power source is a 200KW nuclear generator. Even if you ignore the thrust-to-power ratio, it is obvious that the kinetic energy at the end is many many many times more than what this generator could possibly provide in the amount of time specified.

Interestingly, on slide 11 he somehow claims to be calculating efficiency (based on energy input and final kinetic energy), to be less than 1 but this is clearly wrong given the figures in the previous two slides.

Offline Dortex

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He says 304 N/KW and 1m/s^2 and it looks like he means these to be constant.

340 mN/kw is the closest I could find there. If we got 340 N/kw, there wouldn't be any question as to whether the drive worked, we'd have put it on literally anything that moves by this point and solved the energy problems of the world.
« Last Edit: 06/24/2015 03:41 AM by Dortex »

Offline TheTraveller

He says 304 N/KW and 1m/s^2 and it looks like he means these to be constant.

340 mN/kw is the closest I could find there. If we got 340 N/kw, there wouldn't be any question as to whether the drive worked, we'd have put it on literally anything that moves by this point and solved the energy problems of the world.

The EMDrive is NOT an energy source.

EMDrive generated Force is not Work or Energy.

The power supply provides the Energy for the Force to do Work.
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Offline TheTraveller


The only place where I know that Shawyer has specifically addressed spaceship transit times is last month's Daily Mail article: "Its inventor calculates that an interstellar probe would take ten years to reach two-thirds the speed of light, which he sees as pretty much the limit of how fast we could practically travel."  I analyzed that claim here (over on the Feature Article thread) and showed that with T/P < 1/v specific thrust limitation his zero to 2/3 c in 10 years craft would require a power plant which generates at least 97.3 MW/kg.  That is a massive power density and is five orders of magnitude greater than the astounding 1 kW/kg which VASIMR needs for its 39 day trips to Mars.

It is also possible that Shawyer simply forgot to apply his T/P < 1/v when he calculated his interstellar probe acceleration.

These figures for the interstellar probe can be seen in this presentation of Shawyer's: http://www.emdrive.com/iac2014presentation.pdf, specifically slides 9 and 10. He says 304 N/KW and 1m/s^2 and it looks like he means these to be constant. He also says that his power source is a 200KW nuclear generator. Even if you ignore the thrust-to-power ratio, it is obvious that the kinetic energy at the end is many many many times more than what this generator could possibly provide in the amount of time specified.

Interestingly, on slide 11 he somehow claims to be calculating efficiency (based on energy input and final kinetic energy), to be less than 1 but this is clearly wrong given the figures in the previous two slides.

The ship obeys A = F/M. It cares not about accumulated KE or velocity.

The EMDrive generates a constant Force. The power supply generates constant energy to enable the Force to do Work on the ship's Mass and Accelerate it according to A = F/M.

Violation of CofE by a constantly accelerating ship is just an unproven theory.
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Offline zero123

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He says 304 N/KW and 1m/s^2 and it looks like he means these to be constant.

340 mN/kw is the closest I could find there. If we got 340 N/kw, there wouldn't be any question as to whether the drive worked, we'd have put it on literally anything that moves by this point and solved the energy problems of the world.

Slide 9 says "304N/KW". That's what I am referring to.

Offline Dortex

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The power supply provides the Energy for the Force to do Work.

And that Force will do Work with the Energy from the power supply as long as we can keep it powered. I'm confused by your interjection. We have a thing that moves around when we turn on the power. Do you have some objection I'm missing here, or are you just in Delta's side of the fence?

Slide 9 says "304N/KW". That's what I am referring to.

Bowing out, then.
« Last Edit: 06/24/2015 04:07 AM by Dortex »

Offline TheTraveller

The power supply provides the Energy for the Force to do Work.

And that Force will do Work with the Energy from the power supply as long as we can keep it powered. I'm confused by your interjection. We have a thing that moves around when we turn on the power. Do you have some objection I'm missing here, or are you just in Delta's side of the fence?

Slide 9 says "304N/KW". That's what I am referring to.

Bowing out, then.

Strictly speaking the EMDrive will NOT move unless an outside force is applied, moving it big end to small end.

Vibration caused that to initially occur.

So just switching it on will not necessarily cause it to move.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
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Offline Dortex

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Strictly speaking the EMDrive will NOT move unless an outside force is applied, moving it big end to small end.

Vibration caused that to initially occur.

So just switching it on will not necessarily cause it to move.

You're the only one I've seen saying this. Even Warp, with his cannibalization of GR, acknowledges that it moves with just power. At the absolute least he hasn't said anything like what you've said. I'm no genius, but I think you're alone on this one.

Offline zero123

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The only place where I know that Shawyer has specifically addressed spaceship transit times is last month's Daily Mail article: "Its inventor calculates that an interstellar probe would take ten years to reach two-thirds the speed of light, which he sees as pretty much the limit of how fast we could practically travel."  I analyzed that claim here (over on the Feature Article thread) and showed that with T/P < 1/v specific thrust limitation his zero to 2/3 c in 10 years craft would require a power plant which generates at least 97.3 MW/kg.  That is a massive power density and is five orders of magnitude greater than the astounding 1 kW/kg which VASIMR needs for its 39 day trips to Mars.

It is also possible that Shawyer simply forgot to apply his T/P < 1/v when he calculated his interstellar probe acceleration.

These figures for the interstellar probe can be seen in this presentation of Shawyer's: http://www.emdrive.com/iac2014presentation.pdf, specifically slides 9 and 10. He says 304 N/KW and 1m/s^2 and it looks like he means these to be constant. He also says that his power source is a 200KW nuclear generator. Even if you ignore the thrust-to-power ratio, it is obvious that the kinetic energy at the end is many many many times more than what this generator could possibly provide in the amount of time specified.

Interestingly, on slide 11 he somehow claims to be calculating efficiency (based on energy input and final kinetic energy), to be less than 1 but this is clearly wrong given the figures in the previous two slides.

The ship obeys A = F/M. It cares not about accumulated KE or velocity.

The EMDrive generates a constant Force. The power supply generates constant energy to enable the Force to do Work on the ship's Mass and Accelerate it according to A = F/M.

Violation of CofE by a constantly accelerating ship is just an unproven theory.

Forget about the constantly accelerating part for just a moment. Just look at Shawyer's probe strictly from a Energy Input vs Kinetic Energy standpoint.

It has a 200KW power source and accelerates for 9.86 years. Total energy that can be produced is 200KW * 9.86 years = 62.2 TJ.

It has a final velocity of 204,429 km/s or 204,429,000 m/s. It's not clear how much the total spacecraft mass is at the end but he does say payload is 1000 kg, so let's just calculate the kinetic energy of the payload only (the total spacecraft will be even more obviously). Classical KE is 0.5*m*v^2 = 0.5(1000kg)(204,429,000 m/s)^2 = 20,895,608 TJ.

Relativistic gamma at that speed is about 1.34, so its contribution to any of these calculation is negligible, compared to the difference in energy.

So, you put in 62.2 TJ using your power source and you got out at least 20,895,608 TJ of kinetic energy (and even more for the whole spacecraft). Do you see the problem now? If not, then where would you say is all of that extra energy coming from?
« Last Edit: 06/24/2015 04:29 AM by zero123 »

The power supply provides the Energy for the Force to do Work.

And that Force will do Work with the Energy from the power supply as long as we can keep it powered. I'm confused by your interjection. We have a thing that moves around when we turn on the power. Do you have some objection I'm missing here, or are you just in Delta's side of the fence?

Slide 9 says "304N/KW". That's what I am referring to.

Bowing out, then.

Strictly speaking the EMDrive will NOT move unless an outside force is applied, moving it big end to small end.

Vibration caused that to initially occur.

So just switching it on will not necessarily cause it to move.

I hate to be the one saying this but you appear to be claiming that no force will be measured unless there is "interference" ie. other forces at play... When all other forces are removed it does nothing.  I seriously hope this is not the case.

Offline kdhilliard

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The ship obeys A = F/M. It cares not about accumulated KE or velocity.

The EMDrive generates a constant Force. ...

Hey Traveller,

I don't believe that anyone is agruing against A = F/M, but what Shawyer does it to limit F (or more specifically the specific thrust -- the amount of F obtainable for a given amount of power fed the EmDrive).

Nowhere in his Theory Paper does he explicitly state T/P < 1/v, but that is what you get by taking equation (16), combining it with his definition of thrust, and taking the limit on Q.  He also gives an example on pg. 8-9 where an EmDrive which has accelerated to 3 km/s is limited to a specific thrust of 333 mN/kW.  (Note that 333 mN/kW = 0.333 (kg m / s^2) / (10^3 kg m^2 / s^3) = 1 / (3 km/s) = 1/v.)

However this is not an emergent property of his theory, but is instead explicitly added on pg. 7-8 where he declares that the output power from the device which is transferred into the device's kinetic energy is equal to the change of the kinetic energy of the device (as measured in the reference frame from which the drive first started accelerating from v=0), and thus P_k = M v a = v T.  With total power equal to the sum P_k and the electrical losses P_e, we automatically have P < v T.

Are you suggesting that his Theory Paper is out of date in this regard, and that he no longer imposes a specific thrust limitation of T/P < 1/v?

Best wishes on your continued recuperation!
Kirk

Offline TheTraveller

The power supply provides the Energy for the Force to do Work.

And that Force will do Work with the Energy from the power supply as long as we can keep it powered. I'm confused by your interjection. We have a thing that moves around when we turn on the power. Do you have some objection I'm missing here, or are you just in Delta's side of the fence?

Slide 9 says "304N/KW". That's what I am referring to.

Bowing out, then.

Strictly speaking the EMDrive will NOT move unless an outside force is applied, moving it big end to small end.

Vibration caused that to initially occur.

So just switching it on will not necessarily cause it to move.

I hate to be the one saying this but you appear to be claiming that no force will be measured unless there is "interference" ie. other forces at play... When all other forces are removed it does nothing.  I seriously hope this is not the case.

If you read what Roger Shawyer is saying in the 2 attached documents that is how the EMDrive functions.

As per attached:
 
Quote
A  number of  methods  have  been  used  in  the  UK,  the  US  and  China  to  measure  the forces  produced  by  an  EmDrive  thruster. In  each  successful  case,  the  EmDrive  force data  has  been  superimposed  on  an  increasing  or decreasing  background  force, generated by the test equipment itself. Indeed,  in  the  UK  when  the  background  force  changes were  eliminated,  in  an  effort to  improve  force  measurement  resolution,  no  EmDrive  force  was  measured. This was clearly  a  result of  attempting  to  measure  the  forces  on  a  fully  static thruster, where T and R cancel each other.  UK  flight  thruster measurements  employ  this  principle  to  calibrate  the  background noise on the force balance prior to carrying out force measurements.

Clear?

The EMDrive is trigger out of DoNothing mode and into Motor or Generator mode by externally applied forces (could be just vibration), upsetting the resonate EM waves in the cavity as per slide 7 attached.

Interesting point is that when SPR did what EWs did, eliminated vibration, measured EMDrive generated Force went to zero.
« Last Edit: 06/24/2015 04:46 AM by TheTraveller »
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Offline SeeShells

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The power supply provides the Energy for the Force to do Work.

And that Force will do Work with the Energy from the power supply as long as we can keep it powered. I'm confused by your interjection. We have a thing that moves around when we turn on the power. Do you have some objection I'm missing here, or are you just in Delta's side of the fence?

Slide 9 says "304N/KW". That's what I am referring to.

Bowing out, then.

Strictly speaking the EMDrive will NOT move unless an outside force is applied, moving it big end to small end.

Vibration caused that to initially occur.

So just switching it on will not necessarily cause it to move.
Honestly it could happen either way, move on its own or need to be pushed. The fulcrum I'm building will detect both ways as it can be free to move or push on scales.

But, wait a minute, if I move just a few microns to deflect a scale, it's moving, right? Just doesn't make sense. Or do you really want to say its mass changes to show deflection on the scale?

Shell

Offline TheTraveller

The power supply provides the Energy for the Force to do Work.

And that Force will do Work with the Energy from the power supply as long as we can keep it powered. I'm confused by your interjection. We have a thing that moves around when we turn on the power. Do you have some objection I'm missing here, or are you just in Delta's side of the fence?

Slide 9 says "304N/KW". That's what I am referring to.

Bowing out, then.

Strictly speaking the EMDrive will NOT move unless an outside force is applied, moving it big end to small end.

Vibration caused that to initially occur.

So just switching it on will not necessarily cause it to move.
Honestly it could happen either way, move on its own or need to be pushed. The fulcrum I'm building will detect both ways as it can be free to move or push on scales.

But, wait a minute, if I move just a few microns to deflect a scale, it's moving, right? Just doesn't make sense. Or do you really want to say its mass changes to show deflection on the scale?

Shell

Just needs some vibration.

The EMDrive is an inertial ratchet. Push it on the small end and it will oppose that push, moving into Generator mode. Push it on the big end and it will support that push, moving into Motor mode.

It may be that EW cooked its own goose then they worked so hard to eliminate vibration, without which the EMDrive will just sit there and get hot.
« Last Edit: 06/24/2015 05:06 AM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
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Offline Econocritic

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The EMDrive is trigger out of DoNothing mode and into Motor or Generator mode by externally applied forces (could be just vibration), upsetting the resonate EM waves in the cavity as per slide 7 attached.

Interesting point is that when SPR did what EWs did, eliminated vibration, measured EMDrive generated Force went to zero.

I appreciate TheTraveler's rather uphill defense of Shawyer.  If there is something to all of this the inventor should have considerable insight.  Would it be possible to incorporate an external force per Shawyer into the Rodal and Aero models to analyze the effects on the EM waves?  Is it possible to model the "upsetting of the resonate EM waves" indicated by TheTraveler?  Maybe movement makes the cavity "pointer" or has another interesting effect from the perspective of the EM waves and maybe I'm completely off base. 

Side Note:  There was a lengthy discussion a while ago about crowd sourced funding mechanisms for NASA Eagleworks.  Although this is not a legal option for a government entity it would be interesting to see a professional private replicator explore this avenue.   
« Last Edit: 06/24/2015 05:35 AM by Econocritic »

Offline SeeShells

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The power supply provides the Energy for the Force to do Work.

And that Force will do Work with the Energy from the power supply as long as we can keep it powered. I'm confused by your interjection. We have a thing that moves around when we turn on the power. Do you have some objection I'm missing here, or are you just in Delta's side of the fence?

Slide 9 says "304N/KW". That's what I am referring to.

Bowing out, then.

Strictly speaking the EMDrive will NOT move unless an outside force is applied, moving it big end to small end.

Vibration caused that to initially occur.

So just switching it on will not necessarily cause it to move.
Honestly it could happen either way, move on its own or need to be pushed. The fulcrum I'm building will detect both ways as it can be free to move or push on scales.

But, wait a minute, if I move just a few microns to deflect a scale, it's moving, right? Just doesn't make sense. Or do you really want to say its mass changes to show deflection on the scale?

Shell

Just needs some vibration.

The EMDrive is an inertial ratchet. Push it on the small end and it will oppose that push, moving into Generator mode. Push it on the big end and it will support that push, moving into Motor mode.

It may be that EW cooked its own goose then they worked so hard to eliminate vibration, without which the EMDrive will just sit there and get hot.
Everything vibrates, well maybe a bose condensate chilled just a bit above absolute 0c doesn't.  So as a motor where does it get the EMF to push against being a closed box that nothing (Shawyer said so) escapes? The internal QV of the device?

Honestly the generator and motor explanation goes against everything that makes sense even quantum theory make more sense to me.   



Shell

Offline WarpTech

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I think I just proved my hypothesis, with an open ended cone anyway. Very simply put, the cone shape has an inductance gradient that acts as a particle accelerator. A constant DC Current flowing around the cone perimeter at the big end will feel a force toward the small end. The current will "fall" in that direction, losing energy (and mass) in the process. At the same time, an equal and opposite force is acting on the magnetic flux contained in the current loop, pushing the flux out the back of the cone.
Write up soon!
Todd

Offline demofsky

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I think I just proved my hypothesis, with an open ended cone anyway. Very simply put, the cone shape has an inductance gradient that acts as a particle accelerator. A constant DC Current flowing around the cone perimeter at the big end will feel a force toward the small end. The current will "fall" in that direction, losing energy (and mass) in the process. At the same time, an equal and opposite force is acting on the magnetic flux contained in the current loop, pushing the flux out the back of the cone.
Write up soon!
Todd

Excellent!  Does this require the duty cycle like that seen in magnetrons?  Would increasing the duty cycle increase thrust?  Thanks!

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