Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1805144 times)

Offline Paul Novy

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(...) the water float idea is probably the best of all for seeing thrust directly - and its dynamics. (...)

1. Place the device on the old fashioned Foucault test bench.

2. See the air currents around.

3. ??

4. PROFIT


Offline Paul Novy

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As far as I understand, with this test setup it can't be due to the air buoyancy or air heating up in general.

I think that it is rather due to the fact that their built an electric motor, where emdrive assembly is a rotor.

Offline Flyby

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That 720 mN came from about 1 KW of power. The Baby EmDrive uses not kilowatts, not Watts, but milliwatts. You need to adjust your expectations accordingly.
2.5kW IIRC...

But you misunderstood my motivation: it's not that i want 720mN out of a handful of milliwatts.
But what's needed is hardcore evidence that there is indeed a force developing withing an RF flooded  frustum.

Al we have now are questionable results where it is way to difficult to detect real thrust data from static noise.

Although all those tests give - let me reword it carefully here - an "indication" there might be something going on, the water is still too murky to see clearly...

That's why I in favor for drastically increasing power (even if that means increasing thermal issues) so that thrust signals clearly separate themselves from all the noise...

Unless the baby EMdrive is able to generate a clear spin on its own, well above other effects, it is of little use except for providing another "indication".

In courtrooms they make a distinction between "evidence" and "an indication of evidence".
On the science level, we've had plenty of indications by now, time to fork out the evidence this time...

It doesn't need to float 1 ton of force for me... no need for floating cars as evidence...just a few hundreds of mN , not to be attributed to any already (thermal, magnetic, etc) known effect, would be enough, i think...

Although i do want to believe it and I am supportive to the cause/quest, I do remain a skeptic, until a more tangible result is produced....
And i suspect I'm not the only one... :)
« Last Edit: 06/11/2015 09:19 AM by Flyby »

Offline Paul Novy

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That 720 mN came from about 1 KW of power. The Baby EmDrive uses not kilowatts, not Watts, but milliwatts. You need to adjust your expectations accordingly.

It doesn't need to float 1 ton of force for me... no need for floating cars as evidence...just a few hundreds of mN , not to be attributed to any already (thermal, magnetic, etc) known effect, would be enough, i think...



Well, someone might built a one meter frustum and connect it to a couple megawatts (continuous power) klystron at 300 Mhz but no one will spend such amount of money without clear evidence.

Offline rfmwguy

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The skeptic in me is alive and well but curiosity is also. I will test it for myself, half mythbuster half believer. Think this balance is important as the experiments begin. Still awaiting exciter board and amp. Frustum shaper done and working out endplate mounting schemes. Simple balance beam for first test with laser pointer. Full size 2.4 Ghz frustum with about 8 watts and hoping for 1.5 kg mass. Pushing the power to weight ratio, but hey, been there done that. project update for nsf complete  ;)

Offline Paul_A

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The guys from hackaday.io posted an update with some raw data graphs: https://hackaday.io/project/5596-em-drive/log/19330-original-recordings

I am greatly enjoying the discussion here on NSF, its a great learning experience and should be used in lessons at schools and universities as an example of the scientific method (which many scientists are forgetting nowadays).
« Last Edit: 06/11/2015 10:14 AM by Paul_A »
Dr. A. Paul, Geologist and Space enthusiast

Offline PaulF

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Disturbing to se the EM Drive's strange preference of one direction vs. another (reminds me of the issue with NASA turning it around by 180 degrees). 


I have been wondering if a preferred frame means that there is a specific velocity at which it appears one should be at rest.  I would suspect that this might be so.  Far away from a gravity well, maybe we can assume space is stationary, and light speed is about the same in any direction from a 3rd observer displaced from all gravity.  Inside a gravity well however, lets assume space time is moving into the gravity well.  With a black hole, at the event horizon lets say, space is moving in at the speed of light.  At that point light cant escape because space is moving in at the same speed it propagates.  Maybe we are not at rest in our own frame inside earths gravity well with respect to space. 
...
While reading this, I asked myself the following:

How is that, as spacetime expands, the matter in our universe is dragged outward along with it (or is this my misconception?) and that the invisible part is receding from us at greater than the speed of light (Vgalaxies + Vspacetime), while with a black hole spacetime is dragged in, and acceleration toward the black hole is solely due to gravity. Vmax = c, not c + speed of dragged spacetime. Why is that? Due to time dilation / length compression? Is this a proprietary property of a black hole, being able to stretch spacetime into itself without dragging in matter at V > c ?

Can anyone clear this up for me with a good explanation?

-PS maybe a better question is: Why can expanding spacetime without gravity well expell matter from "us"at V>c while a blackhole with it's monster gravity can suck in spacetime so brutally but fail to suck in matter at V>c ?

This article kind of helped me with your question.  Here is a quote, "how we could possibly see a galaxy that is moving away from us faster than the speed of light! The answer is that the motion of the galaxy now has no effect whatsoever on the light that it emitted billions of years ago. The light doesn't care what the galaxy is doing; it just cares about the stretching of space between its current location and us. So we can easily imagine a situation where the galaxy was not moving faster than the speed of light at the moment the light was emitted; therefore, the light was able to "outrun" the expansion of space and move towards us, "

http://curious.astro.cornell.edu/about-us/104-the-universe/cosmology-and-the-big-bang/expansion-of-the-universe/616-is-the-universe-expanding-faster-than-the-speed-of-light-intermediate

So in a sense I think that when the light was emitted the velocity of the space it passed through never went above the speed of light so it made it to us but was still stretched due to the expansion (red shifted).  This seems to imply that if the space light passes through does go above the speed of light then the light doesn't reach us and may be similar to a black hole but with an event horizon that surrounds us.  In a sense everything freezes at the event horizon and time stops so it doesn't go above light speed but then maybe the universe does that to hide anything that does go above c. 

It is an interesting subject in that it seems to suggest space is moving and dragging us with it.

Actually what I inferred was Galaxies receding from us at V>c, not the light in any respect. I know that galaxies that are now to far for us too see (> 13.6 Gigalightyears), but their light will reach us eventually. I know all this. We know fairly certain the universe is much larger. The fact is that these galaxies ARE receding from us at V>c. Which means spacetime expansion MUST drag matter along.

Offline Prunesquallor

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The guys from hackaday.io posted an update with some raw data graphs: https://hackaday.io/project/5596-em-drive/log/19330-original-recordings

I am greatly enjoying the discussion here on NSF, its a great learning experience and should be used in lessons at schools and universities as an example of the scientific method (which many scientists are forgetting nowadays).

OK excellent, they defined "prograde" and "retrograde" - same spin direction, with a reversal in thruster orientation.  Now if we just had data on a non-thrusting run so we could see the natural spin damping effects.
Retired, yet... not

Offline Prunesquallor

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I'm trying to deduce the thrust from the Baby Emdrive data, and failing.

Let q represent dw/dt or the angular acceleration (always < 0), where
q0 is the acceleration with the drive off = -29.408
q+ is the acceleration with the drive prograde (impeding decay) = -24.987
q- is the acceleration with the drive retrograde (assisting decay) = -35.007
where the numbers have been read off from the interpolated graphical slopes.

Let b = the constant frictional force acting against the motion (Newtons)
Let F = the drive force (Newtons)
Let a = I/R, so that a*q is also in Newtons (torque = moment of inertia * dw/dt)

Then we have 3 equations in 3 unknowns:
1. a q0 = -b
2. a q+ = -b + F
3. a q- = -b - F

For consistency we are forced to have
2 q0 = q+ + q-
and from the interpolated graphical slopes, this is quite nicely the case (58.82 vs. 59.99).

However, we cannot solve for F independently of a or b.
Bummer. Or am I being stupid?

Its difficult for me to wrap my head around what the natural anguiar deceleration should be, which is why I would like to see more of the non-thrusting behavior. On the one hand, if it were due primarily to "smooth" aerodynamics, the decelerating torque should be proportional to the square of the angular rate. On the other hand, the airflow in the jar may be completely chaotic or vortical making prediction impossible. On the third hand, is there a magnetic dampening torque?
« Last Edit: 06/11/2015 11:08 AM by Prunesquallor »
Retired, yet... not

Offline Vix

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Well, someone might built a one meter frustum and connect it to a couple megawatts (continuous power) klystron at 300 Mhz but no one will spend such amount of money without clear evidence.

Chicken and egg thing. Well, this is what I advocate too. It should be built by some lab. They must accept the risk that it will prove nothing, or it may be a breakthrough. It is expensive for a Diy-er, but it's a peanut for the Defense industry...
« Last Edit: 06/11/2015 11:29 AM by Vix »

Offline Flyby

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Well, someone might built a one meter frustum and connect it to a couple megawatts (continuous power) klystron at 300 Mhz but no one will spend such amount of money without clear evidence.

Chicken and egg thing. Well, this is what I advocate too. It should be built by some lab. They must accept the risk that it will prove nothing, or it may be a breakthrough. It is expensive for a Diy-er, but it's a peanut for the Defense industry...

But first you need to persuade skeptics that it actually works. And for that you need thrust signals that go well beyond possible side effects and measurement artifacts.

Before research and development of the EMdrive goes any further it will have to build up some credibility first. None of the established institutes wants to participate in what could turn out the biggest hoax of this decade...
« Last Edit: 06/11/2015 12:33 PM by Flyby »

Offline Vix

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History repeats itself. Which reminds me of Leo Szilard in the 1930'es. Skeptics need a proof first.  :(
As it looks now, it could easily happen that the Chinese will provide it...
« Last Edit: 06/11/2015 01:01 PM by Vix »

Offline rfmwguy

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Well, someone might built a one meter frustum and connect it to a couple megawatts (continuous power) klystron at 300 Mhz but no one will spend such amount of money without clear evidence.

Chicken and egg thing. Well, this is what I advocate too. It should be built by some lab. They must accept the risk that it will prove nothing, or it may be a breakthrough. It is expensive for a Diy-er, but it's a peanut for the Defense industry...

(...)

Before research and development of the EMdrive goes any further it will have to build up some credibility first. None of the established institutes wants to participate in what could turn out the biggest hoax of this decade...

Its a shame many R&D outfits may be taking a political view like this. There is no shame in disproving anything, although I'm not sure awards are given for this; unlike the opposite. If I help disprove the EMDrive contentions, I'll personally be pleased to contribute to the body of research without the need of a rewards plaque...but thats just me...

Offline Rodal

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Flight Thruster build update:

From the best photo of the Flight Thruster I could find and allowing for 2mm thick walls, to add thermal mass and reduce the rate of thermal expansion, the following internal Flight Thruster dimensions were obtained:

Length:   138.6mm
Small diameter:   125.7mm
Big diameter:   231.4mm

Applying those to my spreadsheet generated:

Df:   0.638
Frequency:   3.85GHz
Mode:   TE013

I then asked Roger Shawyer did I get close? His reply:

Df:  0.635
Frequency:   3.9003GHz
Mode:   TE013

I'm VERY happy with that as my Rf gen can easily go to that frequency. Time now to finalise drawings and get some copper sheet laser cut.

Roger also mentioned it is best to give the internal frustum surfaces a nice bright shinny polish. No need for Silver or Gold overcoats.

I was reviewing the data for the Flight Thruster to include in the EM Drive wiki, and I noticed the following differences:


                               Length(m)                       BigDiameter(m)
TheTraveller:            0.1386                            0.2314
Shawyer's paper:      0.164                              0.265
Difference:               18%                                15%

Where Shawyer's paper reference means this paper:

page 9 of IAC- 08 C4.4.7, MICROWAVE PROPULSION PROGRESS IN THE EMDRIVE PROGRAMME, Roger Shawyer  (http://www.emdrive.com/IAC-08-C4-4-7.pdf)

QUESTION: What is the reason for the 18% difference ?  (If this was previously discussed in other posts, I forgot)
and how do we know which one is correct?

If the difference is due to using external dimensions (Shawyer's paper) or internal dimensions (TheTraveller) then this would imply that the wall thicknesses (assuming given by the difference in radii) are:

lateral walls=((265-231.4)/2) mm= 16.8 mm (0.661 inches)

which are much, much thicker than what NASA Eagleworks used
               

« Last Edit: 06/11/2015 03:00 PM by Rodal »

Offline TheTraveller

Flight Thruster build update:

From the best photo of the Flight Thruster I could find and allowing for 2mm thick walls, to add thermal mass and reduce the rate of thermal expansion, the following internal Flight Thruster dimensions were obtained:

Length:   138.6mm
Small diameter:   125.7mm
Big diameter:   231.4mm

Applying those to my spreadsheet generated:

Df:   0.638
Frequency:   3.85GHz
Mode:   TE013

I then asked Roger Shawyer did I get close? His reply:

Df:  0.635
Frequency:   3.9003GHz
Mode:   TE013

I'm VERY happy with that as my Rf gen can easily go to that frequency. Time now to finalise drawings and get some copper sheet laser cut.

Roger also mentioned it is best to give the internal frustum surfaces a nice bright shinny polish. No need for Silver or Gold overcoats.

I was reviewing the data for the Flight Thruster to include in the EM Drive wiki, and I noticed the following differences:


                               Length(m)                       BigDiameter(m)
TheTraveller:            0.1386                            0.2314
Shawyer's paper:      0.164                              0.265
Difference:               18%                                15%

Where Shawyer's paper reference means this paper:

page 9 of IAC- 08 C4.4.7, MICROWAVE PROPULSION PROGRESS IN THE EMDRIVE PROGRAMME, Roger Shawyer  (http://www.emdrive.com/IAC-08-C4-4-7.pdf)

QUESTION: What is the reason for the 18% difference ?  (If this was previously discussed in other posts, I forgot)
and how do we know which one is correct?

If the difference is due to using external dimensions (Shawyer's paper) or internal dimensions (TheTraveller) then this would imply that the wall thicknesses (assuming given by the difference in radii) are:

lateral walls=((265-231.4)/2) mm= 16.8 mm (0.661 inches)

which are much, much thicker than what NASA Eagleworks used
               

Any dimensional data Shawyer provides is always external overall dimensions. Then you use photos to estimate internal dimensions. I used 2mm thick walls for the Flight Thruster to give more thermal mass & less dimensional movement during thrust pulses.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
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Offline SeeShells

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(...) the water float idea is probably the best of all for seeing thrust directly - and its dynamics. (...)

1. Place the device on the old fashioned Foucault test bench.

2. See the air currents around.

3. ??

4. PROFIT


True It's going to have thermal currents around the Frustum container but not quite like the hair drier we see. ;) They should be relatively uniform around the Frustum. I should look at the error that these can have in thrust measurements from an almost randomized flow of pressure differentials around the Frustum container and if it's going to lead in significantly skewing the data.

Offline TheTraveller

History repeats itself. Which reminds me of Leo Szilard in the 1930'es. Skeptics need a proof first.  :(
As it looks now, it could easily happen that the Chinese will provide it...

Shawyer has stated he will release a new peer reviewed Superconducting EMDrive in 2015, created with the assistance of other companies SPR works with. He normally releases at IAC meetings. Next is mid Oct 2015.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline Rodal

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...

I was reviewing the data for the Flight Thruster to include in the EM Drive wiki, and I noticed the following differences:


                               Length(m)                       BigDiameter(m)
TheTraveller:            0.1386                            0.2314
Shawyer's paper:      0.164                              0.265
Difference:               18%                                15%

Where Shawyer's paper reference means this paper:

page 9 of IAC- 08 C4.4.7, MICROWAVE PROPULSION PROGRESS IN THE EMDRIVE PROGRAMME, Roger Shawyer  (http://www.emdrive.com/IAC-08-C4-4-7.pdf)

QUESTION: What is the reason for the 18% difference ?  (If this was previously discussed in other posts, I forgot)
and how do we know which one is correct?

If the difference is due to using external dimensions (Shawyer's paper) or internal dimensions (TheTraveller) then this would imply that the wall thicknesses (assuming given by the difference in radii) are:

lateral walls=((265-231.4)/2) mm= 16.8 mm (0.661 inches)

which are much, much thicker than what NASA Eagleworks used
               

Any dimensional data Shawyer provides is always external overall dimensions. Then you use photos to estimate internal dimensions. I used 2mm thick walls for the Flight Thruster to give more thermal mass & less dimensional movement during thrust pulses.
OK, I understand you are saying that the dimensions given by Shawyer are external dimensions, but I don't understand the difference between the dimensions and your saying that you used 2mm walls.

Please take a gander at my message again, I calculate the walls to be 16.8mm based on the discrepancy between the data, while you give 2 mm.  Those are off by a huge factor of eight (8x). (2mm*8= 16mm)

Any further comments as to why there is this huge discrepancy (a factor of 8 times in the wall thickness)?
« Last Edit: 06/11/2015 03:20 PM by Rodal »

Offline TheTraveller

...

I was reviewing the data for the Flight Thruster to include in the EM Drive wiki, and I noticed the following differences:


                               Length(m)                       BigDiameter(m)
TheTraveller:            0.1386                            0.2314
Shawyer's paper:      0.164                              0.265
Difference:               18%                                15%

Where Shawyer's paper reference means this paper:

page 9 of IAC- 08 C4.4.7, MICROWAVE PROPULSION PROGRESS IN THE EMDRIVE PROGRAMME, Roger Shawyer  (http://www.emdrive.com/IAC-08-C4-4-7.pdf)

QUESTION: What is the reason for the 18% difference ?  (If this was previously discussed in other posts, I forgot)
and how do we know which one is correct?

If the difference is due to using external dimensions (Shawyer's paper) or internal dimensions (TheTraveller) then this would imply that the wall thicknesses (assuming given by the difference in radii) are:

lateral walls=((265-231.4)/2) mm= 16.8 mm (0.661 inches)

which are much, much thicker than what NASA Eagleworks used
               

Any dimensional data Shawyer provides is always external overall dimensions. Then you use photos to estimate internal dimensions. I used 2mm thick walls for the Flight Thruster to give more thermal mass & less dimensional movement during thrust pulses.
OK, I understand you are saying that the dimensions given by Shawyer are external dimensions, but I don't understand the difference between the dimensions and your saying that you used 2mm walls.

Please take a gander at my message again, I calculate the walls to be 16.8mm based on the discrepancy between the data, while you give 2 mm.  Those are off by a huge factor of 8. (2*8= 16)

Any further comments as to why there is this discrepancy?

Maybe LOOK at the photos. Notice the really wide & thick flanges on the ends. Need to subtrace 2x the flange width, then 2mm for wall thickness from the 265mm overall width to get big end internal diameters.
« Last Edit: 06/11/2015 03:24 PM 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 Rodal

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...
Maybe LOOK at the photos. Notice the really wide & thick flanges on the ends. Need to subtrace 2x the flange width, then 2mm for wall thickness from the 265mm overall width to get big end internal diameters.
OK, but Shawyer never reported the flange widths in his papers, to my knowledge.

So, what should I put in the wiki, that:

1) You guesstimated the flange widths from the photographs
or that
2) You got the internal dimensions from Shawyer?

How do you know that Shawyer used 2 mm wall thickness?

Thanks
« Last Edit: 06/11/2015 03:48 PM by Rodal »

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