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#3520 by TheTraveller on 04 Jul, 2016 16:45
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What you are seeing in the rate of change plots, is an EmDrive getting freq lock from the maggie and rapidly generating 18mN or so of force and as the initial torque load is zero, it achieves it's highest acceleration. Then as the wire twists, the increasing torque load reduces the rate of change as would be expected until either the maggie drops lock and thrust stops or the torque load matched the accelerative torque and further deflection stops, or the maggie power stops before reaching max torque load and any remaining kinetic / velocity in the system generates further non powered on deflection until finally the twisting wire has absorbed all the energy delivered by the EmDrive to the load.
What I see in this plot from Dave's 1st data share (vertical scale has been converted into mm of deflection) is the EmDrive powered on and maintained an averaged rate of change of 130um / 0.8 sec for 30 seconds. Note Rate Of Change is amplified 100 times so 13mm on the left scale means 130um Rate Of Change / 0.8 sec time interval.
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Is this theory based on measurements you have taken while Dave was performing his experiments or is it your opinion? The whole purpose of building an em-drive and mounting it on a torque pendulum is to perform enough experiments under different conditions to be able to eliminate noise and error sources. We need to separate real data from the noise. I am still waiting for someone to use just heat as a driving force. Stick a big resistor inside the fustrum and take measurements. Referring to aircraft motion, torque pendulum experiments are instrumented to measure yaw. There is also pitch and roll. These other movements have their own time constants. The oscillations seen in Dave's data may be from pitch or roll. If data was collected where the magnetron was not powered this oscillation may be present. This is another experiment that could be done to isolate contributions to the waveform seen when the magnetron is energized.
Dave test rig has all that as illustrated.
My analysis is done using Dave's data. Do you have an issue with the Rate Of Change data? I researched Dave's Laser Displacement Instrument and worked out the conversion from Volts of displacement to MM of displacement, which was 0.216vdc / mm, which Dave agrees with.
In the attachment maggie power was flowing over the wires and the maggie was pumping 900Wrf into the frustum via the internal to the frustum antenna and also heating itself up, yet there was no movement for 30 secs, until the maggie freq locked and Force was generated.
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#3521 by TheTraveller on 04 Jul, 2016 16:52
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Look I understand you have not altered your beliefs since you 1st post on this forum and it would appear that nothing anybody can show will cause that to alter. I could be wrong.
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You have consistently ignored major, blatant contradictions that have been pointed out to you, and you have refused to consider any other perspectives or explanations other than your own (or those you get from Shawyer).
Rodal has stated quite frequently what kind of experiment it would take to convince him there is a useful force here. On the other hand, you have never stated anything that could convince you that this force is not real.
Before accusing someone of refusing to change their minds who has repeatedly asked for a specific type of experimental data, why don't you offer at least as much consideration for their perspective? Or acknowledge that Shawyer's claim of a self accelerating cavity with no external applied force (breaking the definition of conservation of momentum) is incompatible with Shawyer's claim of following existing physics (which is based upon conservation of momentum) before expecting people to trust you as a good judge of whether or not something is an experimental artifact.
Here is your big problem. You refuse to acknowledge ANY of the existing experimental data is valid. I have said it before and I will repeat it again. 2016 is not going to be a good year for those that deny the experimental data.
There is no point in further "Theory says it can't work" discussions. The experimental data will speak for itself.
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#3522 by SeeShells on 04 Jul, 2016 16:55
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Use a heat lamp facing the large end, that should provide a known quanity thermal profile.
He should run the experiment with the magnetron heating the air at the big end but without exciting the EM Drive. For example by installing a copper plate inside the EM Drive right after the magnetron, to close off any excitation of the EM drive, but allow the heating of the big end air to take place.
Then compare results.
Yes, a dummy test with just heating on the magnetron's side would be great for figuring out if heating is the only source of thrust (or just part of it).
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#3523 by SeeShells on 04 Jul, 2016 17:03
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What you are seeing in the rate of change plots, is an EmDrive getting freq lock from the maggie and rapidly generating 18mN or so of force and as the initial torque load is zero, it achieves it's highest acceleration. Then as the wire twists, the increasing torque load reduces the rate of change as would be expected until either the maggie drops lock and thrust stops or the torque load matched the accelerative torque and further deflection stops, or the maggie power stops before reaching max torque load and any remaining kinetic / velocity in the system generates further non powered on deflection until finally the twisting wire has absorbed all the energy delivered by the EmDrive to the load.
What I see in this plot from Dave's 1st data share (vertical scale has been converted into mm of deflection) is the EmDrive powered on and maintained an averaged rate of change of 130um / 0.8 sec for 30 seconds. Note Rate Of Change is amplified 100 times so 13mm on the left scale means 130um Rate Of Change / 0.8 sec time interval.
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Is this theory based on measurements you have taken while Dave was performing his experiments or is it your opinion? The whole purpose of building an em-drive and mounting it on a torque pendulum is to perform enough experiments under different conditions to be able to eliminate noise and error sources. We need to separate real data from the noise. I am still waiting for someone to use just heat as a driving force. Stick a big resistor inside the fustrum and take measurements. Referring to aircraft motion, torque pendulum experiments are instrumented to measure yaw. There is also pitch and roll. These other movements have their own time constants. The oscillations seen in Dave's data may be from pitch or roll. If data was collected where the magnetron was not powered this oscillation may be present. This is another experiment that could be done to isolate contributions to the waveform seen when the magnetron is energized.
Dave knows that there are many more tests to do and has stated so and I look forward to them, we need to realize this is the first volley on a long road of testing.
I told Dr. Rodal that the one thing is (paraphrase) Dave has some of the cleanest data sets to start to work with and I'm looking forward to others. We may just find some answers, it's time.
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#3524 by Rodal on 04 Jul, 2016 17:03
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In the FFT you can clearly see the harmonics of the system, it's been years since I've played around with FFT but some things stay.
The long sloped decay in red you see the torsional wire non-linear response on the 26 pounds of beam and drive weight. In other words as the beam gets closer to center the force it puts on the beam decreases.
Shell
Shell
This is the FFT of an exponential decay, like a thermal exponential decay.
It looks very much like the FFT one calculated:
looks like a thermal exponential decay to me -
#3525 by zen-in on 04 Jul, 2016 17:05
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In the attachment maggie power was flowing over the wires and the maggie was pumping 900Wrf into the frustum via the internal to the frustum antenna and also heating itself up, yet there was no movement for 30 secs, until the maggie freq locked and Force was generated.
But you don't know if that delay was from the time it took the magnetron to lock or if it was because of some other reason. No one took measurements of the magnetron frequency during this experiment. And magnetrons emit a broadband spectrum of RF so what is there to "lock" anyway? This whole concept of magnetron "locking" does not make sense at all. It is not some kind of PLL. We also don't know what the sampling rate was. That delay before movement may just be a measurement artifact. If you are not there when the experiment is done and given the paucity of information on the protocol and data, no one can make these assumptions. -
#3526 by SeeShells on 04 Jul, 2016 17:59
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In the FFT you can clearly see the harmonics of the system, it's been years since I've played around with FFT but some things stay.
The long sloped decay in red you see the torsional wire non-linear response on the 26 pounds of beam and drive weight. In other words as the beam gets closer to center the force it puts on the beam decreases.
Shell
Shell
This is the FFT of an exponential decay, like a thermal exponential decay.
It looks very much like the FFT one calculated:
looks like a thermal exponential decay to me
Let me get this right Dr. Rodal. You're saying that this slow thermal decay is causing a rotational Yaw component (like you would see in the vertical movements on a teeter todder balance beam)?
I'm having a hard time seeing how. Could you please expand in the how?
Dave's thrust is towards the small end during a powered run. Your saying that the heat plume from the decaying thermals causes it to regress back? If we accept that back movement, then somehow the acceleration of the drive maybe powered by the heat signature of the magnetron? And monomorphic's magnetron is in the side wall and he has seen thrusts, how's that possable?
I'd say it's time we debunk this and ask Dave to put a 500w heat lamp onto the back of his drive facing the large endplate and observe the profile of the beam. You don't want to use the magnetron and block it off, as it will fail from the increased VSWR being reflected back.
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#3527 by meberbs on 04 Jul, 2016 18:06
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Look I understand you have not altered your beliefs since you 1st post on this forum and it would appear that nothing anybody can show will cause that to alter. I could be wrong.
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You have consistently ignored major, blatant contradictions that have been pointed out to you, and you have refused to consider any other perspectives or explanations other than your own (or those you get from Shawyer).
Rodal has stated quite frequently what kind of experiment it would take to convince him there is a useful force here. On the other hand, you have never stated anything that could convince you that this force is not real.
Before accusing someone of refusing to change their minds who has repeatedly asked for a specific type of experimental data, why don't you offer at least as much consideration for their perspective? Or acknowledge that Shawyer's claim of a self accelerating cavity with no external applied force (breaking the definition of conservation of momentum) is incompatible with Shawyer's claim of following existing physics (which is based upon conservation of momentum) before expecting people to trust you as a good judge of whether or not something is an experimental artifact.
Here is your big problem. You refuse to acknowledge ANY of the existing experimental data is valid. I have said it before and I will repeat it again. 2016 is not going to be a good year for those that deny the experimental data.
There is no point in further "Theory says it can't work" discussions. The experimental data will speak for itself.
Yet again, you do not respond to any of the points I made. What would convince you there is no force? And can you acknowledge that Shawyer's claims are self-contradictory? This remains an issue whether the EMdrive works or not.
Shawyer has demonstrated he doesn't understand how to do a force balance, and has not provided the experimental setup descriptions with enough detail to be validated. The only other experiment I have rejected was Yang's and Yang later retracted that data.
The rest of the experimental data is not conclusive either way, there are some null results (but possibly not sensitive enough) and some that show some force but can't rule out other effects such as thermal (I agree with some others here that rfmwguy's data looks more like thermal than a useful thrust due to the way it decays slowly).
2016 is halfway over now, and while there has been some DIY progress, the main relevant event so far has been us finding out about Yang's retraction of any claimed force. Does your statement mean you can share an estimate of about when you will have your self-contained rotary rig available, I believe someone else expressed interest in this timeframe as well. -
#3528 by Rodal on 04 Jul, 2016 18:34
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Let me get this right Dr. Rodal. You're saying that this slow thermal decay is causing a rotational Yaw component (like you would see in the vertical movements on a teeter todder balance beam)?
I'm having a hard time seeing how. Could you please expand in the how?
Dave's thrust is towards the small end during a powered run. Your saying that the heat plume from the decaying thermals causes it to regress back? If we accept that back movement, then somehow the acceleration of the drive maybe powered by the heat signature of the magnetron? And monomorphic's magnetron is in the side wall and he has seen thrusts, how's that possable?
I'd say it's time we debunk this and ask Dave to put a 500w heat lamp onto the back of his drive facing the large endplate and observe the profile of the beam. You don't want to use the magnetron and block it off, as it will fail from the increased VSWR being reflected back.
Shell
No, that's backwards.
I'm saying that the force being measured by rfmwguy was due to thermal convection, due to the magnetron at the big end heating the air.
I also stated that it took Lebedev in 1900 to figure out that electromagnetic radiation tests should be performed in a partial vacuum, because it has been known for over a century that thermal convection effects overwhelm the experimental results otherwise.
The slow exponential thermal decay, like in every thermal exponential decay is due to turning the source of the heat off. It takes a long time for the thermal system to come back to equilibrium.
Your explanation is backwards, the exponential decay is not due to the arrival of a new force suddenly coming into the picture, instead it is due to the slow decrease with time of the already existing force that torqued the torsional pendulum in the first place: the thermal convection force due to the magnetron on rfmwguy's EM Drive big end
The whole angular displacement vs. time in rfmwguy's experiment can be explained thermally as an interaction with the pendulum dynamics. Including as I said the well-known fact that transient response of a dynamic system is higher than the steady state response (no it doesn't take an explosive blast, this happens with any transient as long as inertial forces due to acceleration come into play, it is purely due to the initial conditions)
Then when he turns the magnetron off, there is an exponential decay as the thermal system (the environment in rfmwguy's garage) comes to thermal equilibrium. -
#3529 by masterharper1082 on 04 Jul, 2016 18:43
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This is exactly correct. There is a mechanism for a yaw moment to be produced. Heating of the end causes a natural convection air flow up due to buoyancy. Air velocity up can cause a pressure differential, and thus a force towards the hot end. This should cause a small displacement of the torsional pendulum in the direction of the hot end....
In the FFT you can clearly see the harmonics of the system, it's been years since I've played around with FFT but some things stay.
The long sloped decay in red you see the torsional wire non-linear response on the 26 pounds of beam and drive weight. In other words as the beam gets closer to center the force it puts on the beam decreases.
Shell
Shell
This is the FFT of an exponential decay, like a thermal exponential decay.
It looks very much like the FFT one calculated:
looks like a thermal exponential decay to me
Let me get this right Dr. Rodal. You're saying that this slow thermal decay is causing a rotational Yaw component (like you would see in the vertical movements on a teeter todder balance beam)?
I'm having a hard time seeing how. Could you please expand in the how?
Dave's thrust is towards the small end during a powered run. Your saying that the heat plume from the decaying thermals causes it to regress back? If we accept that back movement, then somehow the acceleration of the drive maybe powered by the heat signature of the magnetron? And monomorphic's magnetron is in the side wall and he has seen thrusts, how's that possable?
I'd say it's time we debunk this and ask Dave to put a 500w heat lamp onto the back of his drive facing the large endplate and observe the profile of the beam. You don't want to use the magnetron and block it off, as it will fail from the increased VSWR being reflected back.
Shell
Use the heat lamp to get the end at a steady temperature similar to when the maggie is running. There may some small torque oscillations due to vortices being formed.
Sent from my SM-T710 using Tapatalk
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#3530 by tchernik on 04 Jul, 2016 18:57
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This is exactly correct. There is a mechanism for a yaw moment to be produced. Heating of the end causes a natural convection air flow up due to buoyancy. Air velocity up can cause a pressure differential, and thus a force towards the hot end. This should cause a small displacement of the torsional pendulum in the direction of the hot end.
Use the heat lamp to get the end at a steady temperature similar to when the maggie is running. There may some small torque oscillations due to vortices being formed.
Sent from my SM-T710 using Tapatalk
In that case shouldn't the thermal thrust go towards the big end in Dave's setup?
AFAIK if his experiment the magnetron is place at the big end. -
#3531 by SeeShells on 04 Jul, 2016 19:05
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I think it might be a smart thing to keep the magnetron bracket in place but remove the tube and insert a 500 w quartz lamp in it's place. That shouldn't be too hard to build a little bracket to hold it in the magnetron frame.
A 500w quartz lamp should provide enough thermal activity to profile the beams reactions.
Shell
Or on thinking about it more you could use a Curling Iron as well.
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#3532 by Rodal on 04 Jul, 2016 19:15
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Whatever you do, it has to get as hot as the magnetron does, and the power per unit surface has to be nearly the same. It would not be valid to put something that gets much hotter or not as hot, or something that has much smaller area delivering heat into the air.
I think it might be a smart thing to keep the magnetron bracket in place but remove the tube and insert a 500 w quartz lamp in it's place. That shouldn't be too hard to build a little bracket to hold it in the magnetron frame.
A 500w quartz lamp should provide enough thermal activity to profile the beams reactions.
Shell
The best way would be to use the magnetron itself to heat the air and figure out a way of not exciting the cavity without ruining the magnetron.
Otherwise enough thought has to go into figuring out something that puts similar power, with similar area being heated.
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#3533 by zen-in on 04 Jul, 2016 19:27
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Whatever you do, it has to get as hot as the magnetron does, and the power per unit surface has to be nearly the same. It would not be valid to put something that gets much hotter or not as hot, or something that has much smaller area delivering heat into the air.
The best way would be to use the magnetron itself to heat the air and figure out a way of not exciting the cavity without ruining the magnetron.
Otherwise enough thought has to go into figuring out something that puts similar power, with similar area being heated.
I think someone suggested this before: Buy two identical magnetrons and bore out one, replacing the innards with a solid resistor. A few Globar elements mounted in a metal enclosure might do the trick. Duplicate experiments could be run by swapping out the functioning magnetron for the heat only unit. If the weight and power consumption were the same only differences in the thermal resistance between the two would affect the results.
It may even be possible, with careful design, to use a low inductance resistor that is driven directly by the magnetron's HV supply. There are companies that make high wattage low inductance Globar resistors.
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#3534 by frobnicat on 04 Jul, 2016 20:25
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Simulated heating : or just do it from the exterior with a 500W spot fixed on lab. frame (not on moving assembly) ? For instance paint big end plate (exterior) in black and project onto it. The spot might generates its own convection that could interfere with the moving assembly though, mm, a thin plastic membrane to isolate that would melt, a glass would stop the IR that makes a large fraction of the 500W of a halogen type spot, cold lights (leds) at real 500W illumination would be costly, sun is inconvenient (needs a few mirrors to get 500W into the surface area)... Anyway, think from a simple halogen spot on tripod directly beamed from 2 or 3 feet away on blackened frustum from a few angles and temperature checks we could learn quite a few things (concerning effect of frustum heating specifically, not so much about magnetron heating) at little cost and minimally invasive modifications to the setup.
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#3535 by X_RaY on 04 Jul, 2016 20:28
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Short question:
Was the measured force (whatever the cause is) forward the small or the big end in rfmwguy's experiment?
If the movement was forward the big base it could be because of a huge numbers of thermal driven electrons drifting away from the magnetron along the copper sidewalls of the frustum, the back reaction against the acceleration of the rest mass of the electrons could explain a lot in this regard.
However a NULL test under similar conditions using a cylindrical cavity would be enlightening.
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#3536 by Rodal on 04 Jul, 2016 21:08
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Simulated heating : or just do it from the exterior with a 500W spot fixed on lab. frame (not on moving assembly) ? For instance paint big end plate (exterior) in black and project onto it. The spot might generates its own convection that could interfere with the moving assembly though, mm, a thin plastic membrane to isolate that would melt, a glass would stop the IR that makes a large fraction of the 500W of a halogen type spot, cold lights (leds) at real 500W illumination would be costly, sun is inconvenient (needs a few mirrors to get 500W into the surface area)... Anyway, think from a simple halogen spot on tripod directly beamed from 2 or 3 feet away on blackened frustum from a few angles and temperature checks we could learn quite a few things (concerning effect of frustum heating specifically, not so much about magnetron heating) at little cost and minimally invasive modifications to the setup.
Thermal convection problems such as this are quite complex and one cannot benefit from much theoretical or numerical work because there has not been much practical interest in analyzing microNewton forces produced by a frustum of a cone with an exposed magnetron at the big end heating the air very inefficiently (as in rfmguys' EM Drive).
As we previously discussed fluid dynamics coupled with heat transfer at small Reynolds number is outside the area of expertise of the DIY builders in these experiments. The computational fluid mechanics resources (expertise, cost of the license for a suitable CFD program, and computational time) are exponentially higher than the electromagnetic simulations that have been carried out.
Since the thermal convection problem at small Reynolds number flow (compared to airplanes) with microNewton forces is not well known, I would be very conservative in how to model this.
It would be best to have the magnetron doing the heating while removing the excitation to the EM Drive, if at all possible and if somebody can come out with an ingenious and safe way to do this. Zen-in had some suggestions.
http://forum.nasaspaceflight.com/index.php?topic=39772.msg1556679#msg1556679 -
#3537 by masterharper1082 on 04 Jul, 2016 21:09
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You understand my expectation properly. We'll see if real life matches my expectations...
This is exactly correct. There is a mechanism for a yaw moment to be produced. Heating of the end causes a natural convection air flow up due to buoyancy. Air velocity up can cause a pressure differential, and thus a force towards the hot end. This should cause a small displacement of the torsional pendulum in the direction of the hot end.
Use the heat lamp to get the end at a steady temperature similar to when the maggie is running. There may some small torque oscillations due to vortices being formed.
Sent from my SM-T710 using Tapatalk
In that case shouldn't the thermal thrust go towards the big end in Dave's setup?
AFAIK if his experiment the magnetron is place at the big end.
Sent from my SM-T710 using Tapatalk
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#3538 by tchernik on 04 Jul, 2016 21:47
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You understand my expectation properly. We'll see if real life matches my expectations...
This is exactly correct. There is a mechanism for a yaw moment to be produced. Heating of the end causes a natural convection air flow up due to buoyancy. Air velocity up can cause a pressure differential, and thus a force towards the hot end. This should cause a small displacement of the torsional pendulum in the direction of the hot end.
Use the heat lamp to get the end at a steady temperature similar to when the maggie is running. There may some small torque oscillations due to vortices being formed.
Sent from my SM-T710 using Tapatalk
In that case shouldn't the thermal thrust go towards the big end in Dave's setup?
AFAIK if his experiment the magnetron is place at the big end.
Sent from my SM-T710 using Tapatalk
I asked Dave and he just said the thrust seems to be towards the small end. -
#3539 by zen-in on 04 Jul, 2016 22:07
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I asked Dave and he just said the thrust seems to be towards the small end.
There has always been confusion with the terminology describing claimed emdrive thrust. A rocket standing vertical and at liftoff from a launch pad produces thrust in a downward direction. And the rocket moves up if the thrust exceeds the weight of the rocket. Shawyer's rotating demo shows his emdrive rotating with the small end leading the big end. Using the analogy of the rocket this would mean the emdrive thrust was from the small end towards the big end. We can use the terminology SMALL-ENDIAN to describe Shawyer's demo. Unless there is some misinterpretation Dave's experiment would be BIG-ENDIAN.
