-
#1400 by Bob012345 on 11 Oct, 2016 18:19
-
[
I truly don't understand. For my (and probably many other's) benefit, can you answer the following question? Suppose EMDrive can provide thrust/power of 10^6/c and it is powered by a battery with energy content of 1 GJ. If the spacecraft (EMDrive+power supply) weighs 1000 kg, how fast will it be travelling after the battery is empty in the (inertial) frame where it starts at rest?
This question as stated makes no sense. The speed is not defined by the spent energy, but by the COM. You have to specify the speed of the reaction mass and calculate the speed of the rocket so that the overall mass center remains fixed.
The question makes perfect sense but one needs to assume a power for the battery. If it's drained at 300kw it can last 3333 seconds which is the same for all observers. The forces 1000N and the acceleration is 1 m/s^2 so and the final velocity is 3.333km/s. This is the same for any assumed power drain but the time will be longer or shorter. Note that simply equating the 1E9J to kinetic energy in the starting frame gives only 1.41km/s. This shows the apparent CoE violation we are debating.
-
#1401 by Bob012345 on 11 Oct, 2016 18:45
-
What precisely does an isolated system mean? It would still conserve momentum correct?
If the device generates a fixed force using electrical power, by whatever means, I think by definition if it conserves momentum it conserves energy.
In physical science (but not thermodynamics) an isolated system is a physical system so far removed from other systems that it does not interact with them.
If the Emdrive works as an isolated system, it does not need anything to interact with. And of course, it violates CoE, and CoM.
If the Emdrive does not work as an isolated system, there is no possible discussion about CoE without having at least hypothesis of how it interacts.
For example, if it is stealing Energy from ZPF, it can accelerate as much as you wish, even with no electrical power needed, you just need to tell that the Kinetic Energy gained in a given referential comes from the ZPF.
At the opposite, if the Emdrive is a way of pushing the ship away from the earth, pushing distantly as a car pushes on the road, your acceleration has to decrease with the speed relatively to the earth to still verify CoE.
You can not discuss CoE without making hypothesis. Isolated/non isolated. And if non Isolated is chosen, the way is is non isolated has much importance also.
I assume the EmDrive conserves both momentum and energy. I just don't know the mechanism however if momentum is conserved, then energy follows as the ship will 'borrow' kinetic energy from the conserved momentum of the 'exhaust' whatever form that is, just as in a rocket where the payload kinetic energy gets higher as it borrows kinetic energy from the exhaust. I guess that makes it non-isolated by your definition.
The recent debate however concerned whether a constant force at a constant power is even possible in classical mechanics which is independent of EmDrives or MET devices. -
#1402 by wicoe on 11 Oct, 2016 19:00
-
The recent debate however concerned whether a constant force at a constant power is even possible in classical mechanics which is independent of EmDrives or MET devices.
My assumption is that it's not possible, and I would be very interested to see a working example of such as system (where the mechanism is well known). The problem is that constant force means constant acceleration, which breaks CoE in faster moving reference frames (since the power spent per time unit is the same). Since you can accelerate only by pushing against something (object, or perhaps some unknown or known field?), your speed relative to that "something" will increase, and it will be harder and harder to push (since you provide a larger increase of kinetic energy to that "something"). -
#1403 by Bob012345 on 11 Oct, 2016 19:02
-
the "power delivered by the force" but you think it's the power necessary to create the force. It's frame dependent. Different frames see different power delivered by the same force which is a clue that it shouldn't be confused as the power necessary to generate that invariant force which is not frame dependent at all
Different frames see the same total power, if you consider the whole interacting system. I.E. if you consider the propellant expelled as making part of the system. You have to do that, since the ship is not isolated from the propellant. Ship+propellant can be an isolated system, and so you can consider Ship+propellant.
Considering Ship+propellant, the power delivered by the force to take into account is the sum of power delivered by the force on the ship, and the power delivered by the force on the propellant. The increase of this sum is limited by the energy spent.
Of course your rocket can get more Kinetic Energy increase in the earth referential that it spent chemical Energy, because it steals Kinetic Energy it to the propellant. It was already explained several times by others. The faster your ship, the most Kinetic Energy it steals to the propellant. That works because the ship is not isolated from the propellant
But if you consider the sum of Kinetic Energy of the ship, and the Kinetic Energy of the propellant, and that ship+propellant is isolated from other systems, this sum never increases more than the Chemical energy spent.
I agree but when you look at the terms, both the gain in kinetic energy of the ship and the loss in kinetic energy of the propellant can dwarf the chemical energy. In the case of an EmDrive or MET device, I believe the ship borrows from the "propellant" even though we don't know what that exactly is. We do know the momentum of the "propellant" is the same as gained by the ship. And the ship borrows from that so the total energy input is whatever the EmDrive needed to make a constant force over a certain time period yet the kinetic energy gain of the ship as well as the loss of the "propellant" are huge in comparison. There is no violation of CoM or CoE. The apparent violation is comparing the total electrical input to the device with the ships final kinetic energy while ignoring the loss of "propellant" kinetic energy during the trip. To me, it's just like a magic rocket that never runs out of fuel and yet the mass remains constant. -
#1404 by wicoe on 11 Oct, 2016 19:08
-
...ignoring the loss of "propellant" kinetic energy during the trip. To me, it's just like a magic rocket that never runs out of fuel and yet the mass remains constant.
Wait, so the propellant already has kinetic energy? Where did it get it from? In the case of the conventional rocket, it gained this energy because it has been accelerating with the rocket (i.e. extra fuel was burnt just to accelerate the propellant). For EmDrive and other such devices, you cannot just assume that the "propellant" happens to have the right kinetic energy and momentum at any given time (i.e. co-moving with the device) so that it can "steal" kinetic energy from it. Makes no sense, right? -
#1405 by Bob012345 on 11 Oct, 2016 19:17
-
...ignoring the loss of "propellant" kinetic energy during the trip. To me, it's just like a magic rocket that never runs out of fuel and yet the mass remains constant.
Wait, so the propellant already has kinetic energy? Where did it get it from? In the case of the conventional rocket, it gained this energy because it has been accelerating with the rocket (i.e. extra fuel was burnt just to accelerate the propellant). For EmDrive and other such devices, you cannot just assume that the "propellant" happens to have the right kinetic energy and momentum at any given time (i.e. co-moving with the device) so that it can "steal" kinetic energy from it. Makes no sense, right?
It's no different from a rocket. The propellant has kinetic energy because the ship already has. And it has a different kinetic energy in very frame. In whatever frame the momentum is conserved, the "propellant" has the energy already associated with that frame. You can't conclude it makes no sense if you don't know what it is.
I suspect the universe can provide momentum from any frame irrespective of velocity. Then, any observer would say that the universe can provide the momentum for a moving ship to borrow in that frame. In effect, every frame is the Center of Momentum of the universe just as every frame see the speed of light the same.
-
#1406 by wicoe on 11 Oct, 2016 19:27
-
It's no different from a rocket. The propellant has kinetic energy because the ship already has. In whatever frame the momentum is conserved, the "propellant" has the energy already associated with that frame. You can't conclude it makes no sense if you don't know what it is.
I suspect the universe can provide momentum from any frame irrespective of velocity. Then, any observer would say that the universe can provide the momentum for a moving ship to borrow in that frame. In effect, every frame is the Center of Momentum of the universe just as every frame see the speed of light the same.
The rocket had to spend extra energy to accelerate the propellant with it. It does not "just have the energy". If, as you say, the universe can "provide" a propellant to steal kinetic energy from in any frame, this means free energy. It's quite easy to think of a device that would convert this into free energy. -
#1407 by Bob012345 on 11 Oct, 2016 19:36
-
The recent debate however concerned whether a constant force at a constant power is even possible in classical mechanics which is independent of EmDrives or MET devices.
My assumption is that it's not possible, and I would be very interested to see a working example of such as system (where the mechanism is well known). The problem is that constant force means constant acceleration, which breaks CoE in faster moving reference frames (since the power spent per time unit is the same). Since you can accelerate only by pushing against something (object, or perhaps some unknown or known field?), your speed relative to that "something" will increase, and it will be harder and harder to push (since you provide a larger increase of kinetic energy to that "something").
A rocket's thrust can be constant in the ships frame as it depends on the dm/dt and the exhaust velocity to first order. It provides an invariant constant force. Of course, the acceleration can change as the mass decreases but that means it actually grows a bit. What does take an increasing power is where an external force is applied to an object in a fixed frame vs. The force being applied within an accelerating frame. -
#1408 by Bob012345 on 11 Oct, 2016 19:38
-
It's no different from a rocket. The propellant has kinetic energy because the ship already has. In whatever frame the momentum is conserved, the "propellant" has the energy already associated with that frame. You can't conclude it makes no sense if you don't know what it is.
I suspect the universe can provide momentum from any frame irrespective of velocity. Then, any observer would say that the universe can provide the momentum for a moving ship to borrow in that frame. In effect, every frame is the Center of Momentum of the universe just as every frame see the speed of light the same.
The rocket had to spend extra energy to accelerate the propellant with it. It does not "just have the energy". If, as you say, the universe can "provide" a propellant to steal kinetic energy from in any frame, this means free energy. It's quite easy to think of a device that would convert this into free energy.
That would be saying that the final kinetic energy must always be equal to the chemical energy content delivered by the fuel and no more. Is that your position? -
#1409 by as58 on 11 Oct, 2016 19:42
-
The question makes perfect sense but one needs to assume a power for the battery. If it's drained at 300kw it can last 3333 seconds which is the same for all observers. The forces 1000N and the acceleration is 1 m/s^2 so and the final velocity is 3.333km/s. This is the same for any assumed power drain but the time will be longer or shorter. Note that simply equating the 1E9J to kinetic energy in the starting frame gives only 1.41km/s. This shows the apparent CoE violation we are debating.
Ok. But what if we harvest 50% of the kinetic energy (with some engineering solution that I will here handwave away), use 1.5 GJ of that more than 2 GJ to recharge the battery to 1 GJ (that extra 50% is to account for inefficiencies) and repeat. What, if anything, stops us from doing that? -
#1410 by wicoe on 11 Oct, 2016 19:49
-
That would be saying that the final kinetic energy must always be equal to the chemical energy content delivered by the fuel and no more. Is that your position?
Actually, less: the final kinetic energy of the rocket equals the chemical energy delivered by the fuel burnt less the total kinetic energy gained by the propellant, and less the energy lost as waste heat. -
#1411 by Bob012345 on 11 Oct, 2016 20:12
-
The question makes perfect sense but one needs to assume a power for the battery. If it's drained at 300kw it can last 3333 seconds which is the same for all observers. The forces 1000N and the acceleration is 1 m/s^2 so and the final velocity is 3.333km/s. This is the same for any assumed power drain but the time will be longer or shorter. Note that simply equating the 1E9J to kinetic energy in the starting frame gives only 1.41km/s. This shows the apparent CoE violation we are debating.
Ok. But what if we harvest 50% of the kinetic energy (with some engineering solution that I will here handwave away), use 1.5 GJ of that more than 2 GJ to recharge the battery to 1 GJ (that extra 50% is to account for inefficiencies) and repeat. What, if anything, stops us from doing that?
Then you'd get there slower. You're just borrowing energy from the "propellant" and using it to charge your battery at the expense of a much slower trip. Summing up all energies would still yield the input energy.
-
#1412 by as58 on 11 Oct, 2016 20:15
-
The question makes perfect sense but one needs to assume a power for the battery. If it's drained at 300kw it can last 3333 seconds which is the same for all observers. The forces 1000N and the acceleration is 1 m/s^2 so and the final velocity is 3.333km/s. This is the same for any assumed power drain but the time will be longer or shorter. Note that simply equating the 1E9J to kinetic energy in the starting frame gives only 1.41km/s. This shows the apparent CoE violation we are debating.
Ok. But what if we harvest 50% of the kinetic energy (with some engineering solution that I will here handwave away), use 1.5 GJ of that more than 2 GJ to recharge the battery to 1 GJ (that extra 50% is to account for inefficiencies) and repeat. What, if anything, stops us from doing that?
Then you'd get there slower. You're just borrowing energy from the "propellant" and using it to charge your battery at the expense of a much slower trip. Summing up all energies would still yield the input energy.
I'm not going anywhere, I'm trying to generate free energy. My scheme would give more than 0.5 GJ per iteration. -
#1413 by TheTraveller on 11 Oct, 2016 20:30
-
http://www.ibtimes.co.uk/emdrive-roger-shawyer-paper-describing-space-propulsion-uavs-finally-passes-peer-review-1513223
29 July 2015QuoteHowever, he has now decided that it would be better to focus on putting EmDrive on to unmanned aerial vehicles, with the view to eventually use the technology in the automobile industry to create feasible flying cars.
"Our aim at the moment is not to necessarily go for these space applications, because they will take so long to come to fruition. So what we've decided as a company is to forget space, and to go for terrestrial transport business, which is huge," Shawyer told IBTimes UK.
"The logic is, if you can lift a vehicle reasonably gently with no large accelerations, then you can manufacture the air frame using much lower technology than would be used on an aircraft."
Shawyer says his firm, Satellite Propulsion Research Ltd, is currently designing a drone that has no propellers or wings, and it plans to carry out the first test flights powered by EmDrive microwave space propulsion in 2017.
Flying cars are currently being invented and prototypes do exist, but they are not exactly cars, but rather, an amalgamation of a car and an aeroplane. Two companies are trying to push this type of technology forward, Terrafugia and Aeromobil, but so far the world has not shown much interest.
"If you're trying to build a flying car, you don't start with an aeroplane, you start with a car. It makes it low cost and more affordable to manufacture an airframe that is more like an automobile body," said Shawyer.
"Hydrogen storage and fuel cells are available and affordable – all of this is in place. People are sick of travelling in two dimensions and sitting in traffic jams. You need to use the three dimensions. Space is a waste of time as it's so slow, and it's not a very big market. Mass transportation and other things are a much bigger market and major automobile manufacturers will be interested."
A member of the Gilo Industries Group, http://www.rotronuav.com builds UAV engines. Fits with SPR designing a EmDrive UAV for RotronUAV. Gilo Industries also fits with building flying cars.
As the IBTimes article is dated 29 July 2015, it would seem SPR & Gilo Industries have been working together for some time.
Just maybe Roger, with the help from Gilo Industries, will achieve his 2017 EmDrive powered drone. -
#1414 by Gilbertdrive on 11 Oct, 2016 20:55
-
I assume the EmDrive conserves both momentum and energy. I just don't know the mechanism however if momentum is conserved, then energy follows as the ship will 'borrow' kinetic energy from the conserved momentum of the 'exhaust' whatever form that is, just as in a rocket where the payload kinetic energy gets higher as it borrows kinetic energy from the exhaust. I guess that makes it non-isolated by your definition.
The recent debate however concerned whether a constant force at a constant power is even possible in classical mechanics which is independent of EmDrives or MET devices.
It is not a problem for the Emdrive, it is a problem for ANY device.
When you study a device, and that you wans to see if CoE is verified, you need to know it is isolated, or not isolated.
It is like if we were studying a bulb that is giving light continuously.
We mesure it weight, and see that is is the same weight each day. We use instruments that confirm that there is no desintegration inside. We confirm that it's chemical composition is stable.
If the bulb works as an isolated system, it is free energy. CoE is broken
If the bulb is plugged to the sector, we just have to mesure the currents, compare them to mesurements of light, and see there is no free energy.
We can not discuss about the bulb respecting or violating CoE without taking into account if it is plugged, or not plugged. If it is not plugged and lighting as long as needed, it is breaking CoE. If it is plugged, there no a priori reason to thing that CoE is violated.
If the Emdrive works like an isolated system, and gives constant thrust for constant power imput it is breaking CoE, AND CoM. As Dr Rodal has written a few days ago, it is an evidence.
-
#1415 by Rodal on 11 Oct, 2016 20:56
-
http://www.ibtimes.co.uk/emdrive-roger-shawyer-paper-describing-space-propulsion-uavs-finally-passes-peer-review-1513223
29 July 2015Quote. ... Space is a waste of time as it's so slow, and it's not a very big market. Mass transportation and other things are a much bigger market and major automobile manufacturers will be interested."
...
So Shawyer, who initially titled his company Satellite Propulsion R. , now, more than a decade later tells the press that Space is a waste of his time ?
Well, the title of this thread is still <<EM Drive Developments - related to space flight applications >> and not to Mass Transportation close to the surface of the Earth, so most of the people at NSF do not share his present view of Space as being a waste of people's time...
Anyway, looking forward to any successful demonstration of a self-levitating EM Drive
A self-levitating EM Drive close to the surface of the Earth will be a convincing proof for any skeptic to see -
#1416 by TheTraveller on 11 Oct, 2016 21:06
-
http://www.ibtimes.co.uk/emdrive-roger-shawyer-paper-describing-space-propulsion-uavs-finally-passes-peer-review-1513223
29 July 2015Quote. ... Space is a waste of time as it's so slow, and it's not a very big market. Mass transportation and other things are a much bigger market and major automobile manufacturers will be interested."
...
So Shawyer, who initially titled his company Satellite Propulsion R. , now, more than a decade later tells the press that Space is a waste of his time ?
Well, the title of this thread is still <<EM Drive Developments - related to space flight applications >> and not to Mass Transportation on the surface of the Earth, so most of the people at NSF do not share his present view of Space as being a waste of people's time...
Maybe quote all that he said:Quote"Our aim at the moment is not to necessarily go for these space applications, because they will take so long to come to fruition. So what we've decided as a company is to forget space, and to go for terrestrial transport business, which is huge," Shawyer told IBTimes UK.
Would suggest that a Gilo Industries EmDrive powered UAV will be very big news. And Roger is correct. A UAV can happen much faster and for a lot less money than a launch vehicle space application.
I'm sure if NASA rolled out the red carpet and allocated a few 100 million for R&D, they would have sometime in 5 to 10 years. But so far NASA can't find the money to keep Paul employed, so you really think the money to support EmDrives in space is ready to leap out of the budgets that are Ion drive directed?
You did read Roger is predicting a EmDrive wingless and propellerless drone in 2017? How many times have I read, "Show me it floating over my head"?
Well it seems that is going to happen. I suspect the space application of the technology will happen REALLY FAST after the drone starts flying over people's heads. -
#1417 by Gilbertdrive on 11 Oct, 2016 21:07
-
http://www.ibtimes.co.uk/emdrive-roger-shawyer-paper-describing-space-propulsion-uavs-finally-passes-peer-review-1513223
29 July 2015Quote. ... Space is a waste of time as it's so slow, and it's not a very big market. Mass transportation and other things are a much bigger market and major automobile manufacturers will be interested."
...
So Shawyer, who initially titled his company Satellite Propulsion R. , now, more than a decade later tells the press that Space is a waste of his time ?
Well, the title of this thread is still <<EM Drive Developments - related to space flight applications >> and not to Mass Transportation on the surface of the Earth, so most of the people at NSF do not share that view of Space as being a waste of people's time...
I agree. But maybe we can forgive Shawyer in this point because of his personal situation.
Since many years he claims that his Emdrive works, and no space realisation was made. That personnal experience can give him the idea that there is not market for it in space.
Even with superconductive Emdrive, I do not see how it could be competitive with Electric cars. Except of course if it is giving constant thrust for constant power. In that case the first application should be a power generating device. A big rotating system at high speed linked to alternators. If the speed is high enough, it gives more energy that it needs. (I shall not speak of free energy, because it can be stolen to QV, fields, etc) -
#1418 by Gilbertdrive on 11 Oct, 2016 21:12
-
I'm sure if NASA rolled out the red carpet and allocated a few 100 million for R&D, they would have sometime in 5 to 10 years.
You did read Roger is predicting a EmDrive wingless and propellerless drone in 2017? How many times have I read, "Show me it floating over my head"?
Well it seems that is going to happen. I suspect the space application of the technology will happen REALLY FAST after the drone starts flying over people's heads.
What Q is needed to make fly a drone stationary ? It seems difficult. -
#1419 by TheTraveller on 11 Oct, 2016 21:14
-
Even with superconductive Emdrive, I do not see how it could be competitive with Electric cars. Except of course if it is giving constant thrust for constant power. In that case the first application should be a power generating device. A big rotating system at high speed linked to alternators. If the speed is high enough, it gives more energy that it needs. (I shall not speak of free energy, because it can be stolen to QV, fields, etc)
That is getting a bit old. There is no energy generation. Just a few folks here may need to adjust their frame reference to the EmDrive and forget what happens in other frames.
Roger has already run the numbers on his rotary test rig and sorry to say but no free energy and A = F/M rules the day.
