Hello everyone! This is my first post on this forum (so I hope i'm doing it right!), but some of you may know me as a regular contributor to that other forum...
For my first post, I wanted to share some FEKO runs I did a few weeks back of a typically sized frustum but with different dipole antenna locations and orientations. The goal was to characterize the internal near fields and surface current since many say that antenna location is the "super squirrel secret sauce." Next goal is to do a frequency sweep of each of the antenna locations.
What took you so long?
Glad you're here. You're doing just fine. Keep updating us. I just received my material for the new frustum. Machining starts soon. - Dave
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Is it possible that a vibration could cause enough mechanical distortion to allow a resonance to establish itself in a less than perfectly tuned frustum/oscillator setup?
Unfortunately the frequency of mechanical vibrations is too many orders of magnitude smaller than the frequency of the electromagnetic resonance in these cavities. For example, for the EM Drive typical natural frequencies excited have been around two gigaHertz (2 *10^9 Hz), while mechanical vibration frequencies are typically kiloHertz or lower, say 2*10^3 Hz or lower, which is about a million times lower frequency.
So, with respect to the electromagnetic frequency, mechanical frequencies of vibration are so much smaller (a million times smaller than electromagnetic frequencies) as to appear practically static in comparison with the electromagnetic frequency. Worse than that, if anything, permanent geometrical distortion of a cavity usually has a deleterious effect on the quality of resonance Q, and so will mechanical vibration (if the vibration has a very high amplitude) since changing the shape of the cavity changes the natural frequency, and hence lowers the Q (assuming that one was operating at the peak resonance for maximum Q).
Piezoelectric devices might be able to oscillate at the requisite frequencies, but it would be nice to kill two birds with one stone and test a low frequency EM drive and a lower frequency mechanical agitator in the same setup.
A piezoelectric device may be able to oscillate a micrometer or nanometer piezoelectric actuator at GigaHertz frequencies (using MEMS technologies ( https://en.wikipedia.org/wiki/Microelectromechanical_systems )), but the micrometer actuator GHz oscillation will not result in gigahertz mechanical resonance of the EM Drive copper cavity (being discussed here, which have lengths of 0.23 meters: dimensions of several inches), which was the subject of the question:
Is it possible that a vibration could cause enough mechanical distortion to allow a resonance to establish itself in a less than perfectly tuned frustum/oscillator setup?
(Bold added for emphasis)
There is a fundamental difference here: the electromagnetic oscillation in the microwave cavity with a given quality of resonance Q is an oscillation of the electromagnetic fields involving the speed of light and not at all a mechanical oscillation of the copper cavity.
The impractical nature of getting the EM Drive copper cavity structure to resonate at GigaHertz frequencies can be illustrated by the following: one thing is to have GigaHertz frequencies of electromagnetic waves in a medium at the speed of light, such that the wavelength is
wavelength = c/frequency
c = 299792458 m / s
for example, at 2.45 GHz,
wavelength = 299792458/2.45*10^9 = 0.122 m = 4.82 inches
compared to mechanical resonance of the EM Drive cavity, with a copper sound speed (*) of
3560 m/s
wavelength = 3560/2.45*10^9 = 1.453 micrometers
So, a frequency of 2.45 GHz involves mode shapes in copper with a wavelength of the order of only 1.453 micrometers, which is a thousand times less than the mm thickness of the copper walls !
This is in the same dimensional scale as the skin depth of penetration of the electromagnetic fields into the copper wall (a micrometer).
It is not physically possible to excite such a mechanical resonance of the microwave cavity. Even if one would use a high explosive, all one would get would be stress wave transient strains in the copper (probably resulting in fracture of the copper wall), but not a mechanical resonant vibration of the cavity.
If one would put a tiny (less than a micrometer in dimension) piezoelectric actuator oscillating at GHz on the EM Drive copper walls, this would not make the 0.23 meter long EM Drive cavity resonate at GHz frequency.
Furthermore it is important to understand that even if one could make a (hypothetically thin) EM Drive cavity (with hypothetical walls thinner than a micrometer) to move at 2.45 GHz with a wavelength of 1.453 micrometers this would not at all produce any sympathetic resonance of the electromagnetic fields in the medium inside the cavity, since the electromagnetic fields speed is the speed of light, which is orders of magnitude higher than the speed of sound in copper, and copper molecules, and their constituent particles cannot get close to the speed of light because they have mass.
You just cannot make the copper walls move in unison with the electromagnetic fields in the cavity.
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(*) stress waves in a solid proceed at the speed of sound in the solid, volumetric stress waves travel at a speed of
where K is the bulk modulus of elasticity of the solid and ρ is the density.
Such stress waves in a solid cannot move at the speed of light because only massless particles like photons can travel at the speed of light. The density of a solid needs to be zero, in order for its sound speed speed to be equal to the speed of light.
Hi all again,
First.
Get your flu shots. It will put you out for a week and a half and maybe in the hospital, or worse. I forgot mine. I was stupid. I caught it. I'm better, weak but better.
Dr. Rodal stress vectors don't need to be in the bending of the copper walls, the walls don't need to move to some outside or inside forces. To a standing or traveling harmonic wave inside of the frustum @ 2.45GHz the walls are quite mechanically nonreactive. I was dreaming of this in my fevered dreams and what we are looking for in the walls moving and coming up with all sorts of schemes to get them to move is to influence the traveling or standing wave in the cavity. If I move the walls I effect the wave actions in a cavity. If I change on how the copper walls are seen by the standing or traveling wave I do the same thing... correct?
https://en.wikipedia.org/wiki/Microwave_cavityIn this wiki article they even mention that dielectrics are used inside of the cavity and that made me think if we can use dielectrices in a cavity why not use diamagnetic materials on the copper walls?
http://www.digikey.com/en/product-highlight/p/panasonic/pyrolytic-graphite-sheets(could be me in younger days)
Also for thermal control
Just wanted to throw this out there for discussion this morning and to let everyone know I'm back and will be finalizing several tests and runs over the coming weeks.
Shell
Hello everyone! This is my first post on this forum (so I hope i'm doing it right!), but some of you may know me as a regular contributor to that other forum...
For my first post, I wanted to share some FEKO runs I did a few weeks back of a typically sized frustum but with different dipole antenna locations and orientations. The goal was to characterize the internal near fields and surface current since many say that antenna location is the "super squirrel secret sauce." Next goal is to do a frequency sweep of each of the antenna locations.
Welcome to the forum
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The mesh looks very coarse, I wonder about convergence. Is the mesh this coarse because you are mesh-limited due to using a Feko size-limited version ?
Glad you are feeling better Shell!
...To a standing or traveling harmonic wave inside of the frustum @ 2.45GHz the walls are quite mechanically nonreactive. ...
That's correct !
and moving the walls (
necessarily at a speed much lower than the speed of light) is not going to help the quality of resonance. If the amplitude of wall movement is large enough, such (comparatively slow movement) will be deleterious to the quality factor of resonance Q, just like the thermal expansion is deleterious to the Q.
*************
By contrast, I think that what TheTraveller had in mind was
not to move the walls at high frequency, but instead to move the center of mass of the EM Drive,
moving the EM Drive as a rigid body, in order to get it "unstuck" from static friction, etc.
_______--
and...Welcome back
...To a standing or traveling harmonic wave inside of the frustum @ 2.45GHz the walls are quite mechanically nonreactive. ...
That's correct !
and moving the walls (necessarily at a speed much lower than the speed of light) is not going to help the quality of resonance. If the amplitude of wall movement is large enough, such (comparatively slow movement) will be deleterious to the quality factor of resonance Q, just like the thermal expansion is deleterious to the Q.
*************
By contrast, I think that what TheTraveller had in mind was not to move the walls at high frequency, but instead to move the center of mass of the EM Drive, in order to get it "unstuck" from static friction, etc.
_______--
and...Welcome back
Thanks for the welcome back.
I'm struggling with the notion and always have with the need to unstick the drive. Unsticky is what I'd think of in EM standing waves, like trying to corral jello in a stainless bowl with jello spoons, very slippery. As a closed frame it sees the rest of the universe as bouncing around. So this is why I was thinking of letting the portion of the EM standing wave interact with a diamagnetic material thereby becoming asymmetrical. That could mean using a diamagnetic material just at one end.
Shell
Added: Physics says that the drive must obey Conservation of Momentum and for every action there is a equal and opposite reaction. The standing wave forces within the resonating chamber including the sidewalls must be equal. But what if we change that a little with adding a diamagmetic material at one end (Se cuttoff). I know I'm just pushing on the windshield so to speak, but it will effect the center of mass of the standing wave.
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Thanks for the welcome back.
I'm struggling with the notion and always have with the need to unstick the drive. Unsticky is what I'd think of in EM standing waves, like trying to corral jello in a stainless bowl with jello spoons, very slippery. As a closed frame it sees the rest of the universe as bouncing around. So this is why I was thinking of letting the portion of the EM standing wave interact with a diamagnetic material. That could mean using a diamagnetic material just at one end.
Shell
Copper is slightly diamagnetic.
Notable diamagnetic materials[2]
Material χv (× 10−5) magnetic susceptibility, where μ= χv + 1.
Superconductor −10^5
Pyrolytic carbon −40.9
Bismuth −16.6
Silver −2.6
Carbon (diamond) −2.1
Lead −1.8
Carbon (graphite) −1.6
Copper −1.0
If you use
TM modes (that have an electric axial field) you could go with
one end made of a more diamagnetic material than copper.
But, alternatively you could go with
TE modes (that have an axial magnetic field) and use
ferromagnetic materials at one end. This is probably going to be much more effective because there are very ferromagnetic materials with high magnetic permeability. This was proposed by DeAquino.
Apologies if this is again at an extremely basic, obvious level...
If the EmDrive is a closed system, doesn't a requirement to overcome "static friction"
again imply a
preferred reference frame that also
conveniently happens to be at rest
with respect to whichever way a test stand is facing on a rotating, orbiting Earth??
Seems highly unlikely to me.
Apologies if this is again at an extremely basic, obvious level...
If the EmDrive is a closed system, doesn't a requirement to overcome "static friction" again imply a preferred reference frame that also conveniently happens to be at rest with respect to whichever way a test stand is facing on a rotating, orbiting Earth??
Seems highly unlikely to me.
No, we are not referring to inertial frames of reference. We are not referring to velocities.
We are referring to accelerations. Accelerating frames are privileged.
A vibration involves acceleration (that's why accelerometers were one of the earliest ways to measure vibrations and they are still used for that purpose). Acceleration involves non-inertial, privileged frames: if you put some scientists inside a box in space they can measure whether they are experiencing acceleration while as you say velocity is relative. (*)
Initial acceleration of the EM Drive could be defended from the point of view that whatever physical mechanism is involved in the EM Drive, if the anomalous force is not an experimental artifact, for the power levels being involved in the present experiments the forces involved are way too small and that some initial acceleration is needed to best overcome extrinsic issues (like static friction being larger than kinematic friction, etc.) or inherent physical issues (negative energy-mass being involved).
So, although TheTraveller never specified the level of acceleration or vibration needed to best "motivate the EM Drive" he did state that he was referring to vibration, and hence initial acceleration.
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(*) Also in a curved spacetime all frames are non-inertial.
...
Thanks for the welcome back.
I'm struggling with the notion and always have with the need to unstick the drive. Unsticky is what I'd think of in EM standing waves, like trying to corral jello in a stainless bowl with jello spoons, very slippery. As a closed frame it sees the rest of the universe as bouncing around. So this is why I was thinking of letting the portion of the EM standing wave interact with a diamagnetic material. That could mean using a diamagnetic material just at one end.
Shell
Copper is slightly diamagnetic If you use TM modes (that have an electric axial field) you could go with one end made of a more diamagnetic material than copper.
But, alternatively you could go with TE modes (that have an axial magnetic field) and use ferromagnetic materials at one end. This is probably going to be much more effective because there are very ferromagnetic materials with high magnetic permeability. This was proposed by DeAquino.
I still see DeAquino as "pushing on the windshield". I know I'm above my pay grade here and still a little foggy from the flu (great fevered dreams about the EMDrive though).
Like you have said even if we change the internal center of mass of the EMDrive it's interaction with the outside world will still remain the same. Something has to poke a hole through the closed frame of the frustum. We need to extract the high energy from the standing waves of a TE or TM mode and turn it into a one way street to the outside.
If we can't get out of the closed frame of the emdrive using dielectrics or diamagnetic materials or evanescent wave energies we have to change the way spacetime sees the drive. With Todd's theory he does get out, as well as notsosureofit's or Dr. White's QV VP particles.
On another note:
I'm upgrading my magnetron to be able to control the heating of it a little better and give me longer run times, greater frequency stability and the solution was quite easy for under a 100 bucks.
I'm wrapping the magnetron with a copper tube heat sink running the copper tube through a radiator. The little 12V pump will give me ~1gpm through the coils and I'll still use the same fan that was in the microwave. I'll post pictures when it's done. Everything should be here today.
http://www.amazon.com/gp/product/B00UZ9HC2U?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00http://www.amazon.com/gp/product/B00CFDS3JA?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00 http://www.amazon.com/gp/product/B00KL1JWZC?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00http://www.amazon.com/gp/product/B000OGX5AM?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00I thought this could be a great solution to those who strap the magnetron onto the sides of the EMDrive and decreasing the thermal plume, just run the line from the magnetron with flexible hose, stress relieve it and drop it down to be coiled it in a bucket of ice water with a pump if you didn't want to use a radiator.
Shell
Apologies if this is again at an extremely basic, obvious level...
If the EmDrive is a closed system, doesn't a requirement to overcome "static friction" again imply a preferred reference frame that also conveniently happens to be at rest with respect to whichever way a test stand is facing on a rotating, orbiting Earth??
Seems highly unlikely to me.
No, we are not referring to inertial frames of reference. We are not referring to velocities.
We are referring to accelerations. Accelerating frames are privileged.
A vibration involves acceleration (that's why accelerometers were one of the earliest ways to measure vibrations and they are still used for that purpose). Acceleration involves non-inertial, privileged frames: if you put some scientists inside a box in space they can measure whether they are experiencing acceleration while as you say velocity is relative. (*)
Initial acceleration of the EM Drive could be defended from the point of view that whatever physical mechanism is involved in the EM Drive, if the anomalous force is not an experimental artifact, for the power levels being involved in the present experiments the forces involved are way too small and that some initial acceleration is needed to best overcome extrinsic issues (like static friction being larger than kinematic friction, etc.) or inherent physical issues (negative energy-mass being involved).
So, although TheTraveller never specified the level of acceleration or vibration needed to best "motivate the EM Drive" he did state that he was referring to vibration, and hence initial acceleration.
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(*) Also in a curved spacetime all frames are non-inertial.
RIGHT. My apologies, I went back and re-read your post #2910 a few pages back. I think my brain got stuck on reference frames when I saw "static friction;" being far more educated than I on these topics I was certain you wouldn't make such an elementary error, but I couldn't shake that particular cobweb.
Now I understand that the EmDrive on a stationary test stand in orbit on a rotating Earth is still in a largely unaccelerated state. That said, I guess the experiment would be "what level of acceleration/vibration is required to "motivate" the anomalous force?" Obviously the Drive is not entirely unaccelerated because there are going to be microtremors in the earth due to seismic activity, nearby highways and construction, & etc., & etc... just ask the LIGO folks.
Anyway. I appreciate your descending to my cognitive level for a moment.
Shells - glad you're feeling better! I have two employees out with sick kids today. Definitely a time-suck on productivity... says the guy reading NSF. :p
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I still see DeAquino as "pushing on the windshield". I know I'm above my pay grade here and still a little foggy from the flu (great fevered dreams about the EMDrive though)....
Yes, of course, anybody and everybody that claims that any internal action by any means will move the center of mass of the EM Drive with respect to external frames of reference, is incorrect, as you say, this is just like you pushing on the windshield, or like moving the furniture to one side.
To move the center of mass one needs an external field or to eject mass or energy out of the EM Drive, that is clear.
...Obviously the Drive is not entirely unaccelerated because there are going to be microtremors in the earth due to seismic activity, nearby highways and construction, & etc., & etc... just ask the LIGO folks. ...
But TheTraveller could reply to you that the EM Drive experiments have not been conducted with an EM drive in space. They have been conducted in laboratory experiments on Earth with devices that to get self-accelerated need to overcome some initial static friction, etc., and he could say that the EM Drive anomalous force in null experiments may have been too small compared with the static friction, etc.
To make the point, obviously if you clamp a chemical rocket to a stand:
You need to un-clamp the chemical rocket from the stand, for the chemical rocket engine to self accelerate and move.
...
I still see DeAquino as "pushing on the windshield". I know I'm above my pay grade here and still a little foggy from the flu (great fevered dreams about the EMDrive though)....
Yes, of course, anybody and everybody that claims that any internal action by any means will move the center of mass of the EM Drive with respect to external frames of reference, is incorrect, as you say, this is just like you pushing on the windshield, or like moving the furniture to one side.
To move the center of mass one needs an external field or to eject mass or energy out of the EM Drive, that is clear.
What if the warping of space that mimics mass within the frustum is converted (devolves) back into massless energy the further away from the warping loci inside the frustum?
That's effectively the same as throwing mass out the back of a rocket. If we move the furniture to one side, then convert the furniture to energy (such as heat), we've effectively thrown it overboard.
Then we keep doing it within the resonant cavity- turning input energy into mass (at least in the narrow bandwidth of the RF source), and the mass keeps devolving back into energy that leaves the frustum, the frustum starts moving.
If we beam a Romulan on board our ship, the Center of mass of the ship changes. If the poor Romulan below gets vaporized, his mass is still onboard the ship and nothing happens. If he gets converted to energy, the Center of mass of the ship changes again.
...
.
What if the warping of space that mimics mass within the frustum is converted (devolves) back into massless energy the further away from the warping loci inside the frustum?
That's effectively the same as throwing mass out the back of a rocket. If we move the furniture to one side, then convert the furniture to energy (such as heat), we've effectively thrown it overboard.
Then we keep doing it within the resonant cavity- turning input energy into mass (at least in the narrow bandwidth of the RF source), and the mass keeps devolving back into energy that leaves the frustum. The frustum starts moving.
If the poor Romulan below gets vaporized, his mass is still onboard the ship. If he gets converted to energy, the CG of the ship changes.
Converting mass to energy inside the spacecraft, and keeping the energy inside the spacecraft, even using matter-antimatter reaction or any process E=mc^2 does no good, and it will NOT accelerate the center of mass with respect to outside space frames, unless you eject the mass or energy out of the spacecraft.
Converting mass to energy inside the spacecraft, and keeping the energy inside the spacecraft, even using matter-antimatter reaction or any process E=mc^2 does no good, and it will NOT accelerate the center of mass with respect to outside space frames, unless you eject the mass or energy out of the spacecraft.
That's what I said.
The warping of space is caused by input energy that eventually leaves the frustum in the form of heat, causing the warping to cease. As long as energy is fed into the cavity, the warp can remain and the illusion of mass creation is maintained. Once the input energy is cut off, the warping ends and the energy leaves the frustum. Converting the effect of mass back into energy is the same as throwing mass overboard.
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I still see DeAquino as "pushing on the windshield". I know I'm above my pay grade here and still a little foggy from the flu (great fevered dreams about the EMDrive though)....
Yes, of course, anybody and everybody that claims that any internal action by any means will move the center of mass of the EM Drive with respect to external frames of reference, is incorrect, as you say, this is just like you pushing on the windshield, or like moving the furniture to one side.
To move the center of mass one needs an external field or to eject mass or energy out of the EM Drive, that is clear.
You are quite right, sometimes if helps to drop back to review the basics. This isn't rocket science, oops it is.
I never was clear either on what TT was saying, is it a little push or a hitting the drive to make it ring or just a loud shout, or a stick of C4.
I need to get some shopping done. Job critical items!
Back later,
Shell
Converting mass to energy inside the spacecraft, and keeping the energy inside the spacecraft, even using matter-antimatter reaction or any process E=mc^2 does no good, and it will NOT accelerate the center of mass with respect to outside space frames, unless you eject the mass or energy out of the spacecraft.
That's what I said.
The warping of space is caused by input energy that eventually leaves the frustum in the form of heat, causing the warping to cease. As long as energy is fed into the cavity, the warp can remain and the illusion of mass creation is maintained. Once the input energy is cut off, the warping ends and the energy leaves the frustum.
Replying to discussions related to conservation of momentum and self-acceleration of a closed system, the above post proposes an open system because <<input energy that eventually leaves the frustum in the form of heat>> (*)
If the EM Drive is in space, the only way that energy can escape in the form of heat is as thermal radiation (
https://en.wikipedia.org/wiki/Black-body_radiation ).
Then essentially this proposal is a very inefficient form of a photon rocket, with energy escaping as photons at relatively low energy in the infrared region (as heat through radiation instead of purposely collimating the photons).
So what is being proposed (escaping heat) can not explain what EM Drive experimenters are claiming: hundreds of thousands greater force/input power than a photon rocket.
this concept is:
* not propellant-less
* even more inefficient that a perfectly collimated photon-rocket
* hence too inefficient compared to other alternatives for space propulsion
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(*) this would be similar to the Pioneer anomaly (
https://en.wikipedia.org/wiki/Pioneer_anomaly ): heat escaping as thermal radiation, which results in extremely small thrust/inputPower
...Obviously the Drive is not entirely unaccelerated because there are going to be microtremors in the earth due to seismic activity, nearby highways and construction, & etc., & etc... just ask the LIGO folks. ...
But TheTraveller could reply to you that the EM Drive experiments have not been conducted with an EM drive in space. They have been conducted in laboratory experiments on Earth with devices that to get self-accelerated need to overcome some initial static friction, etc., and he could say that the EM Drive anomalous force in null experiments may have been too small compared with the static friction, etc.
To make the point, obviously if you clamp a chemical rocket to a stand:
You need to un-clamp the chemical rocket from the stand, for the chemical rocket engine to self accelerate and move.
Yes yes yes. This is why I did the test stand to be able to check pressure and acceleration profiles. Mainly to check out the theory "that it needs a push".
Now I got to get out to do shopping, ran out of Kleenex in a roll.
Shell
...
I still see DeAquino as "pushing on the windshield". I know I'm above my pay grade here and still a little foggy from the flu (great fevered dreams about the EMDrive though)....
Yes, of course, anybody and everybody that claims that any internal action by any means will move the center of mass of the EM Drive with respect to external frames of reference, is incorrect, as you say, this is just like you pushing on the windshield, or like moving the furniture to one side.
To move the center of mass one needs an external field or to eject mass or energy out of the EM Drive, that is clear.
You are quite right, sometimes if helps to drop back to review the basics. This isn't rocket science, oops it is.
I never was clear either on what TT was saying, is it a little push or a hitting the drive to make it ring or just a loud shout, or a stick of C4.
I need to get some shopping done. Job critical items!
Back later,
Shell
Shell, very glad you're better; welcome back!
Just an odd observation. When building the lowest possible phase noise quartz oscillator, the crystal is loaded as lightly as possible to maintain the highest possible Q. Of course, this requires extraordinary amounts of gain in the oscillator feedback loop, and the gain had to be of the lowest possible noise figure.
Between the light coupling, and the low noise, there often wasn't enough flicker or shot noise to get the oscillator to start, sometimes for many minutes. Lightly tapping the circuit with a fingernail was usually enough to make the piezoelectric quartz output a tiny voltage glitch, and the oscillator would...oscillate. The output of the circuit could take several (as many as 15) seconds to slowly build to its final, stable, amplitude.
While a quartz crystal is piezoelectric, and the Emdrive most definitely is not, I hope it is helpful to point out that very high Q circuits can do strange and unexpected things. Inducing mechanical vibration or impulse on a quartz crystal to help it start "doing its thing" is rarely mentioned in the literature. The actual deflection of the crystal during the tap was on the order of nanometers (by calculation). These oscillators had absolute phase noise below -215 dBc/Hz at the floor (offset >100 KHz from a 10 MHz carrier).
