Author Topic: EM Drive Developments - related to space flight applications - Thread 8  (Read 1560572 times)

Offline Star One

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I have not seen anything in the Forbes article that refers to any new finding.  In fact the article is even-handed and points out other peer reviewed papers that were later retracted after being proven false.   I assume the following papers that are mentioned in the article were all retracted:

quoted from recent Forbes article
"
Does it mean the science is correct, the effect is real and that physics is broken? Consider that peer-reviewed journals publish all sorts of results that later turn out to be spurious, including:

    the faster-than-light neutrinos that turned out to be a loose cable,
    the existence of the exoplanet Alpha Centauri Bb, which turned out to not exist,
    and the existence of a new LHC particle at 750 GeV, whose signal went away with more data.

"
end of quote
That last example is poor as I don't believe any of the multiple papers concerning that were ever peer reviewed, if for no other reason lack of time.

Offline dustinthewind

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It would appear from the comments made here, the full EW paper has reached beyond EWs and AIAA. Seems Dr White sent it to Mark Rademaker, who modelled Dr White's IXS Enterprise warp ship. I predict it will see the light of day well before AIAA publishes it.

http://www.forbes.com/sites/startswithabang/2016/09/02/nasas-impossible-space-engine-the-emdrive-passes-peer-review/#6ab6875a692c

The information below was not in that released by Dr. Rodal.  It must be from the full paper:

Quote
For the EMdrive, the device that was tested here, thrust was consistently observed on the device to be between 30-and-50 microNewtons, giving us that 1.2 N/MW figure. But the limits of the measuring device’s threshold was just 10-to-15 microNewtons! In other words, these results may be consistent and interesting, but this isn’t as robust as anyone wants it to be.

I am disappointed to see that "30-50 microNewtons" number. It is just in the range of Lorentz force you would see with a few amperes DC, several hundred cm^2 closed current loop, and the earth's magnet field. It looks like they did not avoid the same old flaw they made in their 2014 paper (see http://arxiv.org/pdf/1510.07752v1 for that flaw). After all, they got to know that flaw after their new test was done.

I was thinking of a solution to eliminating the earths magnetic field from experiments.  One I liked earlier and I can't find the quote was using the 3 axis Helmholtz coils. 

I was thinking of another solution that might be possible is to enclose the EM drive and apparatus in soft iron.  That is a soft iron box is attached to the EM drive it self and moves with it on the pendulum and any magnetic field generated is contained inside the box.  Now to eliminate interaction with earths magnetic field we can use soft iron to enclose the entire pendulum which should shield the inside.  I was hoping it should effectively shield the the em-drive it self from the outside fields.  I ran some simulations to show how two iron boxes can shield interaction of two separate magnetic fields below. 

This seems to be on the same thought process so I added this link: http://www.coolmagnetman.com/magshield.htm quote from link, "What you'll find is that only steel and iron will work as a shield.  If it is very thin, it's effectiveness is decreased.  If you place more layers of the shield between the magnet and the probe, it will be more effective (or thicker pieces of material)."

changed the shielded image to better illustrate my point
« Last Edit: 09/05/2016 03:44 pm by dustinthewind »
Follow the science? What is science with out the truth.  If there is no truth in it it is not science.  Truth is found by open discussion and rehashing facts not those that moderate it to fit their agenda.  In the end the truth speaks for itself.  Beware the strong delusion and lies mentioned in 2ndThesalonians2:11.  The last stage of Babylon is transhumanism.  Clay mingled with iron (flesh mingled with machine).  MK ultra out of control.  Consider bill gates patent 202060606 (666), that hacks the humans to make their brains crunch C R Y P T O. Are humans hackable animals or are they protected like when Jesus cast out the legion?

Offline Monomorphic

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This is what TM212 looks like *without dialectric insert*. 
« Last Edit: 09/05/2016 02:38 am by Monomorphic »

Offline sghill

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Jeez, I go on vacation for three days, and while I'm gone,  the global press goes wild over a single post on this subthread, which is buried in a speculative thread, inside a teeny tiny tech forum that lives off to one side of the Internet. Again!!!

It's a helluva important topic being silently followed all the time by people who don't post, but who are press members (and bots). Please use solid judgement on this thread friends.

...and I'm thrilled to be a part of it.
« Last Edit: 09/05/2016 12:33 pm by sghill »
Bring the thunder!

Offline TheTraveller

To those playing with dielectrics, may I refer you to the best paper on the subject, giving all the frustum dimensions, modes and even the dielectric resonator model and manufacturer plus a detailed explanation of how the dielectric resonator was tuned (position adjusted). Also note the big end plate was also adjustable.

Quote
The thruster was designed around a Siemens dielectric resonator type LN89/52B with a dielectric constant (er) of 38. An operating frequency of 2450 MHz was selected to allow a commercial 850 W magnetron to be used as a power source. A tapered circular waveguide was designed with TM01 as the dominant mode of propagation.

Quote
Finally the overall electrical length of the thruster must be a multiple of e/2 where
e is the effective wavelength of the thruster. This effective wavelength will equate
to different values of physical length throughout the waveguide assembly.

The overall geometry was defined by building a mathematical model of the thruster
based on an Excel spreadsheet. The physical length was divided into 0.5mm sections
and the guide wavelength calculated for each section. The electrical length for that
section was calculated and the summation of the section electrical lengths calculated.
Thus variations of diameters, lengths and er could be modelled, with the target of
achieving an overall electrical length equal to ne/2.

The model also allowed the operation to be modelled in TE11 and TE12 modes, the
nearest unwanted modes. The design was optimised to avoid the possibility of any
unwanted mode operation.

Doing all this achieved a specific force of 18.8mN/kW.

Once you have read the 1st report a few times, as each time you may learn a bit more, you can then start on the excellent technical report on the construction and early static testing of the Demonstrator EmDrive.

Folks this is how EmDrive engineering 101 starts.
« Last Edit: 09/05/2016 04:02 am by TheTraveller »
It Is Time For The EmDrive To Come Out Of The Shadows

Offline Bob Woods

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Jeez, I go on vacation for three days, and the global press goes wild over a single post on this subthread while Im gone. Again!

It's a helluva important topic being silently followed all the time by people who don't post, but who are press members (and bots). Please use solid judgement on this thread friends.

...and I'm thrilled to be a part of it.
We've all been Rodal'd!

Offline Willem Staal

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With the  peer review paper coming in december, its easy to be overenthusiastic about the em drive.
Nothing wrong about the initial idea, but as Roger Shawyer stated very clearly: This device can be potentially dangerous! great fun, but you need to follow the safety rules.  The last thing anyone wants are electocuted corpses in a basement..

Offline Star One

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Quick question wouldn't a super conducting drive be of very little use at this time as we don't have practical room temperature super conducting materials so such a device would constantly have to be cooled down?
« Last Edit: 09/05/2016 10:38 am by Star One »

Offline TheTraveller

Quick question wouldn't a super conducting drive be of very little use at this time as we don't have practical room temperature super conducting materials so such a device would constantly have to be cooled down?

In space all that is needed is to shield the EmDrive from the sun and it will cool to a very low temperature with no auxiliary cooling needed. Cannae plan to use this form of cooling on their thrusters.

http://cannae.com/deep-space-probes

Quote
COOLING
The 5 thrusting cavities are cooled by radiative cooling to deep space. The maximum design temperature of cavity operation is 75 K. The cavities and structural elements around the cavities are coated with a high emissivity black finish. At design power, the thruster cavities receive a combined 73 watts of phase-locked RF power. This power is almost entirely consumed as ohmic heating in the walls of the cavities. The cavities continually radiate this heat to deep space.

The radiating surface area of the thruster section of the probe is approximately 90 square meters. The radiative surface area needed to radiate 73 watts from a temperature of 75 K to 3 K (the effective temperature of deep space) is 40 square meters. When the cavities radiate more than 73 watts of thermal energy, the operating temperature of the cavities drops below 75 K, reducing the radiative power of the cooling mechanism. The system will reach a natural equilibrium temperature that radiates all ohmic heating from the cavity walls. This equilibrium temperature will be below the 75 K maximum design temperature.  Operating temperatures below 75 K will improve the surface resistance characteristics of the YBCO and improve the power-to-thrust performance of the propulsion system.

This radiative cooling system is passive. There are no moving parts to wear out or malfunction. This ensures that the cooling system operational life is sufficient to meet the design lifetime of the probe.

The smaller Cannae Drive cavities are operated intermittently to control the yaw, pitch, and roll of the probe. Cooling requirements on these cavities is minimal compared to the cooling load on the thrusting cavities. The small cavities in the probe also use passive radiative cooling (to deep space) to maintain operating temperature at or below 75 K.

EmDrive Engineering 101.
« Last Edit: 09/05/2016 12:55 pm by TheTraveller »
It Is Time For The EmDrive To Come Out Of The Shadows

Offline Rodal

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Quick question wouldn't a super conducting drive be of very little use at this time as we don't have practical room temperature super conducting materials so such a device would constantly have to be cooled down?

In space all that is needed is to shield the EmDrive from the sun and it will cool to a very low temperature with no auxiliary cooling needed. Cannae plan to use this form of cooling on their thrusters.

http://cannae.com/deep-space-probes

Quote
COOLING
The 5 thrusting cavities are cooled by radiative cooling to deep space. The maximum design temperature of cavity operation is 75 K. The cavities and structural elements around the cavities are coated with a high emissivity black finish. At design power, the thruster cavities receive a combined 73 watts of phase-locked RF power. This power is almost entirely consumed as ohmic heating in the walls of the cavities. The cavities continually radiate this heat to deep space.

The radiating surface area of the thruster section of the probe is approximately 90 square meters. The radiative surface area needed to radiate 73 watts from a temperature of 75 K to 3 K (the effective temperature of deep space) is 40 square meters. When the cavities radiate more than 73 watts of thermal energy, the operating temperature of the cavities drops below 75 K, reducing the radiative power of the cooling mechanism. The system will reach a natural equilibrium temperature that radiates all ohmic heating from the cavity walls. This equilibrium temperature will be below the 75 K maximum design temperature.  Operating temperatures below 75 K will improve the surface resistance characteristics of the YBCO and improve the power-to-thrust performance of the propulsion system.

This radiative cooling system is passive. There are no moving parts to wear out or malfunction. This ensures that the cooling system operational life is sufficient to meet the design lifetime of the probe.

The smaller Cannae Drive cavities are operated intermittently to control the yaw, pitch, and roll of the probe. Cooling requirements on these cavities is minimal compared to the cooling load on the thrusting cavities. The small cavities in the probe also use passive radiative cooling (to deep space) to maintain operating temperature at or below 75 K.

EmDrive Engineering 101.

Cryogenic Engineering involves taking into account cryogenic losses, which does not appear to be explicitly accounted for in the above write-up:

A) Passive technology involves losses of cryogenics, which accumulate with time

18% loss for 6 months in LEO using passive technology according to NASA Ames Cryogenic Fluid Management, using current State of the Art

<<current State of the Art (SOA) for cryo-propellant storage is a loss rate of 3%/month in Low Earth Orbit (LEO) using passive technology. Advances in passive thermal control technology might reduce losses to 1%/month, still an unacceptable rate for a 2+ year mission to Mars. By using cryocoolers to balance the entire parasitic and internally generated heat loads in the cryo-tank, no propellant will be lost, resulting in a Zero Boil Off (ZBO) system, and eliminating the need for oversized tanks and extra propellant. Each pound of propellant tank mass saved is directly tradable for payload mass.>>

http://www.nasa.gov/centers/ames/research/technology-onepagers/cryogenic-fluid-management.html

NOTICE: The claimed advantage of not having to exhaust propellant in this design is compensated by the loss of expensive Ne cryo-cooler  This trade-off should be analyzed !

What is the economic justification for a superconducting EM Drive with Ne passive cooling, involving cryogenic losses of 3% a month, even if it would work?

Observe the tanks for Neon in Cannae's drawing: to be used as a cryogenic fluid below (neon is an expensive choice, why are they showing Ne ?)





* the losses are very dependent on the temperature design, Ne is an expensive choice, neon is useful to cryogenically cool from 25 K to 40 K.

* if the temperature is 75-77K why are they showing Ne instead of N2 in their drawing?

* The fact that they are showing Ne instead of N2, sounds like their design is more like 25 K to 40 K than the above write-up discussion of 75 K

* the colder the temperature, the tougher the problem is.

* Cannae's reported superconducting tests involved suspending their resonant cavity inside a liquid helium-filled dewar.  Liquid Helium's Lambda point (*) temperature is only 2 K - that is very cold in comparison with 75 K !!!
Compare these different temperatures (what they tested at, what they show in the drawing and what they discuss in the above write-up)

Using data from http://www.osti.gov/scitech/servlets/purl/917813 at Lawrence Livermore Lab:

He =   2.17 K  (This is what Cannae tested at)  (*)
H2 = 13.8 K
Ne = 24.6 K (This is what Cannae shows in the above drawings)
N2 = 63.1 K (Cannae discusses 75 K in their write-up)


Quote from:  http://www.osti.gov/scitech/servlets/purl/917813
On most spacecraft, one would use helium as a liquid cryogen of choice (regardless of the device
operating temperature) because the total enthalpy per unit cryogen mass available from the boiling
temperature to 300 K is highest for any fluid (except for hydrogen). Hydrogen is a special case. It has
good heat transfer properties and the largest total enthalpy of any fluid. The problem is its flammability.
Solid hydrogen can be used for space cryogenic cooling of devices (above 13 K) on satellites launched
using non-manned expendable rockets.


B) Active technology: the complexity involved with cryogenic fridge technology

So given the problem with 3% a month loss of cryogenics using passive technology, let's discuss the use of a fridge, to eliminate the losses of cryo-coolant:

* NASA has never deployed a liquid helium fridge in space. All missions (that need it), to our knowledge, have been Dewars + solid Hydrogen or liquid Helium reservoir.  And good luck buying a space-qualified liquid Helium refrigerator (that's what they tested at) to fit in a 6 U CubeSat  :)

*as an aside, cryo-compressed storage of hydrogen is the only technology that meets 2015 DOE targets for ground vehicle  volumetric and gravimetric efficiency

----------------------------------------

(*) to be scientifically rigorous, helium converts into a Superfluid, and has two different fluid phases. This point is called the Lambda point . It never becomes a solid no matter how close we go to absolute zero.  However in the literature (e.g. above report from Lawrence Livermore Lab) this is shown in charts as a triple point in comparison with the other cryogenics (thanks to Zen-In for emphasizing this, as it should have been noted)
« Last Edit: 09/05/2016 09:29 pm by Rodal »

Offline JonathanD

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Cryogenic Engineering 100...

All very interesting.  But at that point it's just a complex engineering problem, no?  If the concept itself is actually valid, the rest is just many hours of work and creative solutions.  That's a huge leap forward considering the entire idea has largely been characterized as a little-understood long-shot that is probably experimental error at best, and fraudulent quackery at worst.

Offline Star One

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Cryogenic Engineering 100...

All very interesting.  But at that point it's just a complex engineering problem, no?  If the concept itself is actually valid, the rest is just many hours of work and creative solutions.  That's a huge leap forward considering the entire idea has largely been characterized as a little-understood long-shot that is probably experimental error at best, and fraudulent quackery at worst.

This maybe the case for space if you're willing to resolve all the issues outlined, but such cryogenic engineering is hardly practical if you wanted to apply this to more terrestrial applications such as your flying car.

Offline JonathanD

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Understood, but if the concept is proven, the resources brought to bear on that engineering problem from private industry would be nothing short of massive.  Getting ahead of ourselves a bit, but certainly looking forward to the peer-reviewed article and the Cannae test flight.  TBH, never thought we'd see it get this far.

Offline zen-in

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Re: Liquid Helium fridges.   
I am familiar with the cryo work done at NASA Ames because I worked in that group for 5 years and contributed to the tests of the Spitzer IRAC focal plane image sensor.   There has been a long program of research in stirling cryocoolers there.  However I am not aware of any liquid Helium fridge development being done.  Among the problems one would have with trying to contain the cryogens are maintaining a sufficiently low pressure in the closed system.   Helium dewars require an insulating layer that shields the Helium from external IR radiation and that contains a high vacuum.    Surrounding that is a liquid Nitrogen dewar.   You cannot have a Helium dewar with any useful amount of hold time without a well designed IR radiation barrier and the surrounding liquid Nitrogen barrier.    Achieving a long cryogen hold time is a black art that few are practiced in.   So, from a practical point of view one would have 2 cryo systems to maintain closed loop.   The cryocoolers would have to keep up with the heat leakage as well as any heat load from the experiment.   If it couldn't do that there would be an explosion.    On the plus side a closed loop cryo system does not have the problem of thrust generation from escaping cryogens.  At least not until it explodes.

Heat dumping to space:
Even though outer space is widely considered a very cold place it is not easy to dump excess heat there because it is a high vacuum.   Heat can only be lost by radiative cooling.   If your cooling radiator or blackbody is illuminated by the Sun or Earth instead of exhausting heat it will gain heat.

« Last Edit: 09/05/2016 04:44 pm by zen-in »

Offline RERT

I find it hard to connect the quote from Cannae with the comments on cryo-coolers.

The Cannae quote speaks of passive cooling, which sounds like it needs no cryo-cooler, no?

Assuming they know what the advantage of propellant-less propulsion is, it's possible they may have twigged that needing a supply of coolant is a bad thing.

But: there are Ne tanks in the drawing, don't know what for. Maybe they need something which is still gaseous when passively cooled.

I agree this is better in space than in your regular flying car.....

Offline Star One

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I find it hard to connect the quote from Cannae with the comments on cryo-coolers.

The Cannae quote speaks of passive cooling, which sounds like it needs no cryo-cooler, no?

Assuming they know what the advantage of propellant-less propulsion is, it's possible they may have twigged that needing a supply of coolant is a bad thing.

But: there are Ne tanks in the drawing, don't know what for. Maybe they need something which is still gaseous when passively cooled.

I agree this is better in space than in your regular flying car.....

I imagine any terrestrial flying vehicles using EM drives are going to be nothing like we know now. Weirdly this is the area something like this would be most useful outside of space as we already have electric cars but we do not have large electric planes for when jets must go.

Offline krio

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In theory, would a pulse radar magnetron at 15Ghz, 200 kW, 0.2 us pulse produce a measurable force at first pulse with 4cm diameter frestrum out of stacked superconductors? Also, do you really need the shape to be round? Round shapes are kinda more expensive in this case

Offline Bob012345

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I find it hard to connect the quote from Cannae with the comments on cryo-coolers.

The Cannae quote speaks of passive cooling, which sounds like it needs no cryo-cooler, no?

Assuming they know what the advantage of propellant-less propulsion is, it's possible they may have twigged that needing a supply of coolant is a bad thing.

But: there are Ne tanks in the drawing, don't know what for. Maybe they need something which is still gaseous when passively cooled.

I agree this is better in space than in your regular flying car.....

I imagine any terrestrial flying vehicles using EM drives are going to be nothing like we know now. Weirdly this is the area something like this would be most useful outside of space as we already have electric cars but we do not have large electric planes for when jets must go.

One can guess they might look more like Shuttlecraft. They would gently lift up with no need of runways or airports, climb to where the atmosphere is thin or basically none, no need to go more than a few Mach since no point on Earth is more than 12,000 miles away, then slow and gently land. I limit the speed so a failure of the lift engines would not force anything like a full orbital re-entry with all that heat. I would also add backup parachutes in my design so it could float back if necessary.

Offline Star One

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I find it hard to connect the quote from Cannae with the comments on cryo-coolers.

The Cannae quote speaks of passive cooling, which sounds like it needs no cryo-cooler, no?

Assuming they know what the advantage of propellant-less propulsion is, it's possible they may have twigged that needing a supply of coolant is a bad thing.

But: there are Ne tanks in the drawing, don't know what for. Maybe they need something which is still gaseous when passively cooled.

I agree this is better in space than in your regular flying car.....

I imagine any terrestrial flying vehicles using EM drives are going to be nothing like we know now. Weirdly this is the area something like this would be most useful outside of space as we already have electric cars but we do not have large electric planes for when jets must go.

One can guess they might look more like Shuttlecraft. They would gently lift up with no need of runways or airports, climb to where the atmosphere is thin or basically none, no need to go more than a few Mach since no point on Earth is more than 12,000 miles away, then slow and gently land. I limit the speed so a failure of the lift engines would not force anything like a full orbital re-entry with all that heat. I would also add backup parachutes in my design so it could float back if necessary.
One thing that some people online need to grasp is even if it works. Will it scale, what other technology do we need such as super conductivity & it's all gone to take a very long time to go from lab bench to trips to Proxima B if ever.

Just to refer back to the OP in this thread with the renewed interest in this topic individuals are quoting stuff out of this thread, it has been noted on a certain other place which follows this topic so please take care in posting.
« Last Edit: 09/05/2016 07:32 pm by Star One »

Offline krio

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Technology to get to Proxima B fast but in one piece? I'd guess - warping space in crossection of the ship so that to the external observer it would seem to be few millimeters in diameter. Not sure if I'm joking

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