Difference between revisions of "Generic EM Drive Information"

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m (Mode Shape: Added more info.)
(Removed the velocity and kinetic energy sections as a result of a conversation with Doctor Rodal about how to handle the corrections provided by later efforts in the forum.)
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This is a location for assorted information concerning EM Drives. Likely applies to all current experimental efforts.
 
This is a location for assorted information concerning EM Drives. Likely applies to all current experimental efforts.
  
== Velocity ==
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== Conservation of Energy Violation ==
  
At constant input power, the thrust, and therefore the acceleration, must decrease with time, to ensure that the spacecraft's (change in) velocity never exceeds 2*Power/Thrust.<ref>[http://forum.nasaspaceflight.com/index.php?topic=36313.msg1314503#msg1314503 Rodal's post concerning the energy/thrust constraint.]</ref> Effectively, White proposes that the maximum velocity possibly achievable for these EM Drives is 2*PowerInput/ThrustForce. This energy constraint is known even from Sutton's textbook on Elements of Rocket Propulsion (equation 19-1 Rocket propulsion elements 7th edition- Sutton).
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Doctor White has proposed that the EM Drive is capable of producing constant thrust at a constant power output. User frobnicat has shown (in the following image) that if this were to be true, then the EM Drive could be utilized as a source of unlimited energy. <ref>[http://forum.nasaspaceflight.com/index.php?topic=37438.msg1369806#msg1369806 frobnicat on using the EM Drive for unlimited energy.]</ref> This of course constitutes a violation of [http://en.wikipedia.org/wiki/Conservation_of_energy Conservation of Energy.]
  
The higher the ThrustForce/InputPower, the lower the maximum velocity of an EM Drive: MAXIMUM VELOCITY OF EM DRIVE = 2 /(thrustForce/PowerInput)
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<img src="http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=29276.0;attach=619549;image" style="width:20%">
#(Brady TE mode) ThrustForce/power: 0.00002131 Newton/Watt --> MaximumVelocity = 2/0.00002131 m/s = 93853 m/s = 93.85 km/s
 
#(Prof. Juan Yang et.al. China)  ThrustForce/power: 0.000290  Newton/Watt --> MaximumVelocity = 2/0.000290 m/s = 6897 m/s = 6.90 km/s
 
#(Cannae Superconducting)  ThrustForce/power: 0.0009524  Newton/Watt --> MaximumVelocity = 2/0.0009524 m/s = 2100 m/s = 2.10 km/s
 
  
The maximum velocity of the EM Drive is inversely proportional to Q: <ref>[http://forum.nasaspaceflight.com/index.php?topic=36313.msg1314529#msg1314529 Rodal's post concerning velocity and Q.]</ref> Therefor the higher the Q, the lower the maximum velocity.
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On the assumption that the results provided by the various experimenting groups are valid, then one of the following two options as provided by user deltamass<ref>[http://forum.nasaspaceflight.com/index.php?topic=36313.msg1370943#msg1370943 detlamass on the Energy Paradox.]</ref> and clarified by user frobnicat <ref>[http://forum.nasaspaceflight.com/index.php?topic=36313.msg1371907#msg1371907 frobnicat on apparent/non-apparent CoE breakage.]</ref> must be true. The options are as follows:
#MAXIMUM VELOCITY OF EM DRIVE = 2 /(thrustForce/PowerInput)
 
#MAXIMUM VELOCITY OF EM DRIVE ~ (2 /(Q*otherParameters))
 
  
== Kinetic Energy ==
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'''Option 1''': Energy is conserved, but there is a preferred rest frame. In essence, the drive has a maximum change in velocity (a decreasing acceleration curve) that it can impart irrespective of its starting velocity. The idea of a preferred rest frame is at odds with [http://en.wikipedia.org/wiki/General_relativity general relativity].
The frame-of-reference kinetic energy issues (for non-relativistic spacecraft speeds) are eliminated by the definition of constant acceleration as acceleration=(delta velocity)/(delta time) so that (delta velocity)=acceleration*(delta time).<ref>[http://forum.nasaspaceflight.com/index.php?topic=36313.msg1315154#msg1315154 Rodal's Post on Changing Kinetic Energy.]</ref> Since from Newton's 2nd law, acceleration=ThrustForce/Mass, the change in velocity is uniquely defined in terms of: ThrustForce, total Mass of the spacecraft and DeltaTime (regardless of velocity-frame-of-reference) directly as (delta velocity)=(ThrustForce/Mass)*(delta time). The intrinsic definition of the change in KineticEnergy of the spacecraft under constant acceleration:
 
*deltaKineticEnergy = (1/2)*Mass*((delta velocity)^2)
 
*deltaKineticEnergy = (1/2)*Mass*([(ThrustForce/Mass)*(delta time) ]^2)
 
  
For the EM Drive to make any sense as a '''closed system''' it implies having memory of its time-history in order to never exceed the critical velocity at which (for constant InputPower throughout the time period (delta time)):
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'''Option 2''': An '''apparent''' breach of conservation of energy is possible, where the mechanism by which conservation of energy is maintained is as yet unknown. An example of a possible solution to this problem is that the drive could in some way be emitting tachyons.<ref>[http://forum.nasaspaceflight.com/index.php?topic=36313.msg1371907#msg1371907 frobnicat on tachyons.]</ref>
 
 
*InputPower*(delta time) = (1/2)*Mass*[(ThrustForce/Mass)*(delta time) ]^2 <ref>Consistent with equation 19-1: Rocket Propulsion Elements 7th edition- Sutton</ref>
 
 
 
If the EM drive conserves momentum by interacting with the QuantumVacuum for example, we have an '''open system''' where momentum will be flowing in or out of the cavity, and therefore the open system should be taken into account in the conservation of kinetic energy (which we have not done) in order to arrive at a satisfactory answer.
 
  
 
== Mode Shape ==
 
== Mode Shape ==

Revision as of 07:48, 19 May 2015

This is a location for assorted information concerning EM Drives. Likely applies to all current experimental efforts.

Conservation of Energy Violation

Doctor White has proposed that the EM Drive is capable of producing constant thrust at a constant power output. User frobnicat has shown (in the following image) that if this were to be true, then the EM Drive could be utilized as a source of unlimited energy. [1] This of course constitutes a violation of Conservation of Energy.

On the assumption that the results provided by the various experimenting groups are valid, then one of the following two options as provided by user deltamass[2] and clarified by user frobnicat [3] must be true. The options are as follows:

Option 1: Energy is conserved, but there is a preferred rest frame. In essence, the drive has a maximum change in velocity (a decreasing acceleration curve) that it can impart irrespective of its starting velocity. The idea of a preferred rest frame is at odds with general relativity.

Option 2: An apparent breach of conservation of energy is possible, where the mechanism by which conservation of energy is maintained is as yet unknown. An example of a possible solution to this problem is that the drive could in some way be emitting tachyons.[4]

Mode Shape

See calculations pertaining to the relationship between thrust and mode shape at Notsosureofit's post and Rodal's response.

The mode-shape to frequency relation is very sensitive to the exact geometrical dimensions of the cavity. [5]

References