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#320 by WarpTech on 07 Dec, 2016 21:07
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The voltage and current "from the supply" is NOT the voltage and current stored in the LC oscillator or inside the frustum. The Supply current is not the Circulating current, they are two different loops in the Mesh diagram. The LC oscillator is NOT a resistor. You are confusing the voltage and current "from the supply", with the voltage and current "inside the oscillator". Inside the oscillator, they are 90 deg out of phase if resistance losses are neglected.
At resonance there are no external reactive components of the load and the LC circuit looks to the generator as a resistor.
You are correct. The "load" at the end of the transmission line, as seen by the "generator" looks like a resistor. No argument there, TT. But the cavity itself, is equivalent to an LC circuit. "inside the LC circuit, there is no load. It is stored energy that oscillates from inductive to capacitive stored energy. The voltage and current "inside" the LC circuit, as it is inside the frustum, are 90 degrees out of phase. You are confusing the lumped component impedance, with what is going on at the individual components.
In the case of the frustum, or any EM field, use the following definitions:
1. An inductor is a tube of magnetic flux. Nothing more.
2. A capacitor is a tube of electric flux. Nothing more.
If you understand these definitions, that these components "are" the flux they store, it should become clear. You are taking about the lumped impedance, and I am talking about the component representation of the E and B fields inside it.
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#321 by M.LeBel on 07 Dec, 2016 21:11
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..... “The E and B fields should stagger in time. At one instant the energy is in the E field and thats all that exists in the cavity at that time. At another time both E and B fields exist but are each weaker together. At another time all the energy is in the B field. But these are all superimposed counter-propagating light waves which is the time evolution of the system as old photons die out, new ones are introduced.” ....
Well, I wouldn’t bet on that. All the em wave models up to now are based on E and B alternatively shaking hands in a perfectly “empty” vacuum. Now, we know better. The vacuum is an electromagnetic tissue, a medium. It is therefore more likely that the em waves are actually gliding as a travelling variation in one property of the medium, like all the other waves we know. .. Time to update the model to fit Casimir and all other clues we have about this medium.
From the start I knew the vacuum was not empty. Logically, how can “nothing” have properties like permeability and permittivity? (and half a dozen more properties..)
Food for thought...
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#322 by otlski on 08 Dec, 2016 00:07
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The Eagleworks torsion pendulum
Doing some calculations, I realised how little we know about the measurement device the Eagleworks team used. Below, I do some estimations and calculations.
What I should like to know, are: moment of inertia, resonant frequency, how much does the frustum moves at a given force, dynamic response.
Information we have: internal dimensions of the vacuum vessel (914 mm long) [Brady et al., 2014; White et al., 2016], mass of the complete frustum system (9.3 kg) and figures from which we can estimate the frequency of the pendulum.
Calculation of the moment of inertia (MoI):
- the pendulum arm, if symmetrical, can be at most ~ 900 mm long. But you have to subtract at least the radius of the frustum (including flange ~160 mm), so the centre-of-gravity of the frustum is then at 900-160)/2 = 370 mm mm from the centre of rotation.
- The mass of the frustum and counterweight are given, e.g., in the attached figure [1]: 9.3 kg with a counterweight of 8 kg (OK, it is probably a bit asymmetrical, but we need only orders of magnitude).
⇨ I = 2 x (0.37^2 x 9.3) ≈ 2.5 kg m^2
the torsion pendulum beam and several parts will give a little contribution, maybe 0.1 kg m^2 in total, so say
I total = 2.6 kg m^2
In the first figure a number of calibration pulses are given [F1]. It can be seen that in this configuration the system is a little overdamped (bigger damping than critical, because it has no ‘overshoot’).
In some other figures overshoots after a stepfunction force can be seen. [F2] for instance, a measurement with a dummy load, shows some ringing which points to a slightly underdamped system. Probably this is because the MoI of the pendulum was less than in the configuration with the full frustum.
From this figure [2] a period of ~ 4 s can be estimated (neglecting the influence of damping).
However, in this configuration the frustum seems to be not present, only a big fat dummy load and a weight (1 kg?). So let’s suppose on both sides there is a mass of 3 kg (at distances of 0.4 m from the centre of rotation), this gives a MoI:
I = 2 x (0.37^2 x 3.0) = 0.8 N m rad^-1
Together with the calculated MoI above, the torsion constant can be calculated:
K = 2.0 N m rad^-1. From some other figures [e.g., F3], the pendulum frequency seems to be closer to 5 s, then I = 1.3 N m rad^-1, so let’s say
K (the torsion constant) = 1.7(3) N m rad^-1 .
This torsion constant corresponds to a steel wire of 5 mm diameter (k = πGd^4 / 32l [ref?]). Quite a thick ‘torsion wire’, but White et al. refer to it as a ‘flexure bearing’, which seems quite justified.
angle of rotation = force x arm length/K, approx. angle = tan(angle) = displacement/arm length
⇨ displacement @ a force of 65 µN ≈ 5 µm
That aint much. I guess (from the figures) the optical displacement sensor has submicrometer resolution (but we don’t know the type).
Are these numbers approximately correct, Paul?
References
Brady et al., 2014.
White et al., 2016.
Attached figures (I think they all come from Paul March / Star-Drive)
[F1] August 18, 2015_Copper Frustum Forward & Reverse Tests_9.3kg Integrated Copper Frustum Test Article with 8kg Counter Balance Force Calibrations.jpg
[F2] Eagleworks_dummyloadtest.jpg
[F3] TE012NoDielectric.jpg
Peter,
In response to a previous post of mine, Paul posted a pdf datasheet for the Bendix style flexures. The spring constant is listed at 0.007 lb-in/deg. I assumed that EW used two of them, one at the top and one at the bottom, for a combined spring constant of 0.014 lb-in-deg. With this in mind I used the EW calibration pulse of 29 Newtons and the resultant displacement of 2 uM to determine the achieved spring rate. My result was 0.32 lb-in/deg which disagreed significantly with the flexure assumption. I concluded that I either made a mistake or that the purposeful gravity pendulum that EW set-up to "stabilize" the apparatus was the majority contributor to the system's torsional response. I considered the magnetic damper's effect but since the cal pulse appeared to reach its final flat-top value, the damper's contribution was negligible.
Dan -
#323 by WarpTech on 08 Dec, 2016 00:11
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As many of you know, SSI hosted the Estes Park Breakthrough Propulsion Workshop last September 20-22, 2016. At that time we said that videos and presentation materials would be available at the SSI site and on YouTube in early December. Thanks to the efforts of our volunteer audio-visual team (Robert Smith, SSI Chief Archivist and Evangelist and Robin Snelson, SSI Executive Director), plus Drs. Heidi Fearn and Lance Williams, among others, we have met that self-imposed deadline. Thanks to all concerned!
Thank you for hosting the Advanced Propulsion workshop, Thank you for inviting me.
The link: http://ssi.org/ssi-releases-bpw2016-videos/
Videos will be posted in sequence over the next few days. PDFs of papers and presentations will be available on the SSI site in a few weeks, and we should be able to generate hardcopy books of the proceedings by early next year for those who are interested.
Thanks again for your patience. I hope Chris Bergin will forgive a minor plug for SSI donations, as well. For those who are interested, go to our home page at www.ssi.org and select your favorite project from the sidebar.
It took me a week, to calm down and be able to sleep all night without waking up at 3AM and going, "OMG, it makes sense". Quite sure after refreshing and renewing my memory with your videos, I'll be in the same pattern for another week. Not complaining, but thanking you for being hosts for a fantastically brilliant group dedicated to the next giant leap for mankind.
My Very Best,
Shell
Watching these videos really gets my brain going too. I can't wait to see the rest of them and refresh my memories! -
#324 by dustinthewind on 08 Dec, 2016 01:11
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Your not holding constant the power your feeding in which equals the losses. I thought the point of using a superconducting cavity was to store more power for the same amount of power fed in.
If you change your input power when you change Q then your stored power Energy may stay the same. Power loss=power supplied [Q(w)*9]*[power_supplied*(1/9)]/w=(Maximum_Energy_Stored)
Dustin,
Cavities store energy and not power.
...
Err. Yeah, that was a typo. -
#325 by Stormbringer on 08 Dec, 2016 01:28
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http://phys.org/news/2016-12-mars-days-expert-discusses-nasa.html
comments from the professional peanut gallery. -
#326 by meberbs on 08 Dec, 2016 02:51
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Well, I wouldn’t bet on that. All the em wave models up to now are based on E and B alternatively shaking hands in a perfectly “empty” vacuum. Now, we know better. The vacuum is an electromagnetic tissue, a medium. It is therefore more likely that the em waves are actually gliding as a travelling variation in one property of the medium, like all the other waves we know. .. Time to update the model to fit Casimir and all other clues we have about this medium.
When you describe the vacuum as a medium, that terminology goes back to aether theory, which we know is wrong. Permeability and Permitivity are fundamental constants of nature, not properties of the vacuum. They are called vacuum values to distinguish them from the modifications that result when you try to measure them in the presence of matter. The way a medium perturbs the apparent values of these constants is distinct from the underlying universal constants. (Similar to trying to measure the mass of something by measuring its acceleration under a constant applied horizontal force, you will get a different value if it is sitting on a surface with friction. You would measure a larger apparent mass than the true value, and can do certain calculations with that value, but that doesn't mean that the real mass of the object changes with the friction of what it sits on.)
From the start I knew the vacuum was not empty. Logically, how can “nothing” have properties like permeability and permittivity? (and half a dozen more properties..)
Food for thought...
As far as updating electrodynamics models for quantum effects like Casimir, it is called "quantum electrodynamics," and physicists have already done it. That is why the Casimir effect was predicted before it was measured.
There is no "food for thought" in your post, it is only stuff that has already been considered by physicists and either incorporated or discarded as wrong. From the perspective of someone who has actually studied physics, it comes across as rather rude to physicists when you say that models should be updated to account for something predicted by the models nearly 70 years ago. If you don't know what you are talking about and want to learn, then you should be asking questions, not making statements that make it sound like you think you know more than the collective body of knowledge of the physicists on this planet. -
#327 by spupeng7 on 08 Dec, 2016 04:14
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2b. A = Grad(Phi). We don't know what the Grad(Phi) is, inside the frustum as a function of time or position. I can't say it is a solution or not since I don't have a function for it, only that this is the type of solution we are looking for. I can assume that over a small enough region, it will hold but I don't have an exact solution. Only these general equations.
Ok. And how is the magnetic field related to A?
"A" can be a superposition of vector fields, both rotational and non-rotational. "B = curl(A)", "E = -dA/dt". "Phi = Integral(A)ds", where "s" is a closed path around the flux being measured. There are many ways the field "A" can be expressed. From the color plots produced by the modelers, we can estimate "A" from "E". That is the easiest way to visualize it for me. In QM, the 4-vector field Au is the EM field, and Maxwell's equations are derived from it. In the Lorenz gauge, <|duAu|> = 0, is generally covariant.
I don't know your level of understanding of these things. Some of your statements imply you are well versed in Maxwell's equations, but others show you're not so familiar with the electrical engineering terms that I use. What is your level of EM Theory and QM comprehension? I do not consider myself an expert, but rather someone with a good intuition and knows just enough of the Math to be dangerous.
If B=curl(A) and A=Grad(\Phi), then B=0 (this is just a vector calculus identity which holds for any twice differentiable scalar field \Phi).
I'm (astro)physicist so engineering terms and to some extent notation is unfamiliar to me.
Punctilious statement of variables is the only solution to this recurrent problem.
We can all understand each other better if we remember that math is the Rosetta stone provided it is adequately decoded by STATING YOUR VARIABLES.
As for asking questions, the questioner may sometimes have to answer her own
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#328 by Peter Lauwer on 08 Dec, 2016 10:32
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The Eagleworks torsion pendulum
Doing some calculations, I realised how little we know about the measurement device the Eagleworks team used. Below, I do some estimations and calculations.
....
K (the torsion constant) = 1.7(3) N m rad^-1 .
This torsion constant corresponds to a steel wire of 5 mm diameter (k = πGd^4 / 32l [ref?]). Quite a thick ‘torsion wire’, but White et al. refer to it as a ‘flexure bearing’, which seems quite justified.
angle of rotation = force x arm length/K, approx. angle = tan(angle) = displacement/arm length
⇨ displacement @ a force of 65 µN ≈ 5 µm
....
Peter,
In response to a previous post of mine, Paul posted a pdf datasheet for the Bendix style flexures. The spring constant is listed at 0.007 lb-in/deg. I assumed that EW used two of them, one at the top and one at the bottom, for a combined spring constant of 0.014 lb-in-deg. With this in mind I used the EW calibration pulse of 29 Newtons and the resultant displacement of 2 uM to determine the achieved spring rate. My result was 0.32 lb-in/deg which disagreed significantly with the flexure assumption. I concluded that I either made a mistake or that the purposeful gravity pendulum that EW set-up to "stabilize" the apparatus was the majority contributor to the system's torsional response. I considered the magnetic damper's effect but since the cal pulse appeared to reach its final flat-top value, the damper's contribution was negligible.
Dan
?? If I convert that, I get 0.0453 N m rad^-1 (I was lazy, I used http://www.numberfactory.com/nf%20torque.htm ) -
#329 by flux_capacitor on 08 Dec, 2016 11:00
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Two important news announced publicly by Dave elsewhere.
First, the sad news:Quote from: rfmwguyPer request by Harold White, they will not be presenting a video by Paul March. Go figure...
By "they" Dave means the Space Studies Institute and by the "video" he means Paul's presentation at the Estes Park Breakthrough Propulsion Workshop on 21 September 2016.
Paul retired from Eagleworks at the end of September. Before or after the workshop? -
#330 by flux_capacitor on 08 Dec, 2016 11:04
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Now, the good news for DIYers:
EmDrive Builders Alert - New Macom Solid State Solution - Magnetron Replacement
This is a new ultra compact 2.5GHz solid-state narrowband microwave amp for new generations ovens: GaN Power Transistor, 18dB gain, fed with only 4W to output 300W!
MAGe-102425-300 product page: https://www.macom.com/products/product-detail/MAGe-102425-300
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#331 by Monomorphic on 08 Dec, 2016 13:05
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Now, the good news for DIYers:
EmDrive Builders Alert - New Macom Solid State Solution - Magnetron Replacement
This is a new ultra compact 2.5GHz solid-state narrowband microwave amp for new generations ovens: GaN Power Transistor, 18dB gain, fed with only 4W to output 300W!
We have looked at these types of transistors before. I picked up one of these for $104: http://tinyurl.com/h568esp
If they were available mounted on a finished board that only required soldering power leads, heat sink, and plugging in the coax, that would be even better!
The manufacturer returned my emails and recommended their more rugged scientific/industrial version. I have its spec sheet linked below.
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#332 by Keith Ness on 08 Dec, 2016 13:21
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All of the operators in your diagram must send the cue balls back to their original position. Maybe you could provide a sketch showing how they do this while "deliberately not scattering" the momentum of the cue balls on the return trip.
I don't think it can be done.
Well the point is they keep it to a minimum. Any simple thrust then counterthrust will more-or-less cancel itself out. So throwing a ball and then stopping it will more-or-less cancel itself out. Push off one wall to move to the center, put the ball in the mechanical arm which has re-extended, and then continue moving to and impact the opposite wall will more-or-less cancel out (although things like rotational motion from the occasional off-center impact could be a hassle to deal with and eventually cancel out).
For a simpler reset example, each ball has a string attached to its top and bottom, each string is attached to a spool system in the floor or ceiling, and each spool system can let out or reel in line as necessary. Of course, ultimately, I'm just talking about the randomization of direction of momentum that would occur in particle scattering from particle-on-particle collision. It seems to me that, as long as I divert some of the rearward momentum of the propellant to lateral, then it should be especially clear that some of the rearward momentum of the propellant will have been diminished.
Something you need to understand, is that the definition of conservation of momentum means that any time you get net motion through a setup like this, it means you made a mistake.
In this case, it seem that you don't understand that momentum is a vector quantity. When the ball with momentum X hits the 2 balls and send them off at 45 degree angles, each of the other 2 balls will have momentum X/sqrt(2), not X/2. This is because the horizontal component of momentum for each is X/2 in order to conserve momentum in that direction. Work this through to the end, and you'll see no pressure difference.
If you find my use of the term "momentum" wrong because I pair it with a direction and that sounds redundant because momentum includes a direction, then I see lots of sources using phrases like "forward momentum", even physics lessons; but if that's not enough for you, then please feel free to substitute in the word "push" or something like that where I use "momentum". If "X/sqrt(2)" means "divide X by 1.41...", then my point will remain the same, since the quotient will still be smaller than X. All I need to do is have some of the propellant's rearward momentum diverted to lateral to make it really clear that not all of the momentum is going rearward anymore. Beyond that, since I'm suggesting limits on the accuracy of the phrase, "and opposite," it would not be surprising if I were to run into trouble with any math based on that phrase, so could you please explain, from an empirical rather than theoretical standpoint, how I have not diverted some of the rearward momentum of the propellant to lateral? It seems quite obvious that I have diverted momentum as such, assuming that conservation of energy holds. In my seven billiard balls example specifically, do you deny that:
-- objects can collide such that momentum transfers from one to the other in a different direction than before the collision, and thus, successive collisions and changes in direction of momentum such as in my diagram can occur?
-- the two balls moving directly towards the top and bottom walls have momentum relative to those walls because of their motion relative to those walls?
-- those two balls inevitably took that momentum away from the cue ball's momentum, and, if conservation of energy is to hold, then rightward momentum has overall been reduced?
Surely you're not suggesting that the balls which are travelling directly towards the top and bottom walls (i.e., parallel to the right wall) have any momentum to the right?(To determine the angles they will go at, you need to apply energy conservation, in this case with equal mass balls, opposing 45 degrees angles with the original ball coming to a complete stop is the right answer for a perfectly elastic collisionn.)
This sounds like what my example says (and then those two balls travelling in opposing 45 degree angles likewise hit two more balls each, which are in turn likewise positioned so they travel in opposing 45 degree angles to the trajectories of the balls which hit them). If you ddin't intend it to concur with my example, then could you please provide more detail, maybe a diagram?
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#333 by graybeardsyseng on 08 Dec, 2016 13:31
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IAC, Adelaide, Australia, Sept, 2017
Phil,
Hi Guys,
I'm very seriously considering setting up an exhibit booth, so to demo my non cryo S band thruster happily spinning and accelerating on a rotary test rig during the conference.
Will any of you guys be going and/or will any of you have a product in the market by then?
All the best,
Phil
of course assuming my health will support that plan
I am working on getting there. Haven't been to an IAC in years but now that I'm (mostly) retired it may work out. And Adelaide is one of my favorite cities in the world - seriously a friendly and beautiful place I recommend to everyone.
Won't have a product to market yet but look forward to seeing your demo - hope your health etc facilitate your attending and demonstrating.
Herman -
#334 by Keith Ness on 08 Dec, 2016 14:01
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A photon rocket is not a gradient in an effective potential energy per kg of field mass. So I'd have to say, no. Thrust in this theory depends on the field mass and the potential gradient it can fall through from one end to the other, and/or from one time to another.
For what it's worth, I saw the temperature difference in a diagram in this link:
http://www.nextbigfuture.com/2015/02/more-emdrive-experiment-information.html
...and thought that the smaller end was, for whatever reason, converting radiation pressure more into linear momentum, and the larger end was converting radiation pressure more into heat.
In this video:
...Shawyer mentions that group velocity decreases with aperture size down to a cutoff point at which waves do not pass through, and says microwave oven screens are a good example, letting visible light through, but blocking the longer microwaves. I do also remember someone saying that cutoff varies with wavelength. Shawyer also says radiation pressure drops off with decrease in group velocity, but what happens at cutoff? I assume reflection, or some other transfer of momentum. So maybe the waves hitting the small end do so with less radiation pressure than the large end, but the waves which are cutoff before reaching the small end still impact at various points on the lateral surface where they get cutoff, in stages based on wavelength, giving radiation pressure in the direction of the small end as they do so. Also, because the lateral surface is cone-shaped, the waves pushing towards the small end hit over a larger surface area than the large end (maybe they also hit less directly but more frequently on average, as there's more surface area but at a less oppositional angle to the resonance than the large end?). So maybe the impacts pushing towards the small end have the same force overall but are more widely distributed overall than those pushing toward the large end, and so more of the force pushing toward the large end converts to more-or-less omni-directional force in the form of thermal motion (heat, which more-or-less cancels itself out) than the force pushing toward the small end.
Shawyer also says the two ends are spherical sections (concentric from what I can see), at least ideally, and so there may also be differences in how convex/concave the surfaces are which make a difference in how well they handle impact.
It's kind of like if a tow-truck driver were to drive up to assist your stalled vehicle, and say, “I can either push your car with my hand for a few minutes, or compact all that energy into one rifle shot at your car. It’s the same amount of energy, so it shouldn’t matter which one I use on your car, right?” Wrong, of course. The rifle shot will convert more of its energy into lateral momentum expressed as tearing a hole through your car, and won’t do much to move your car in one direction. The long hand push will move your car in one direction though, because it converts less into lateral momentum of your car.
So maybe the EmDrive is essentially a photon rocket with the benefit of some resonance, as the large end is "giving way" (in the form of heat) to the resonant waves more than the small end and lateral surface are.
Regardless of the reason the temperature difference exists, it should make people go, "Hmm."
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#335 by meberbs on 08 Dec, 2016 15:16
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If you find my use of the term "momentum" wrong because I pair it with a direction and that sounds redundant because momentum includes a direction, then I see lots of sources using phrases like "forward momentum", even physics lessons; but if that's not enough for you, then please feel free to substitute in the word "push" or something like that where I use "momentum". If "X/sqrt(2)" means "divide X by 1.41...", then my point will remain the same, since the quotient will still be smaller than X. ...
Since you didn't mention vectors at all in your response, I assume that you don't know what vectors are or how to work with them. Please go learn this on your own. I have updated your diagram below to show that when you do the calculations correctly, everything balances perfectly. You probably won't understand this next sentence until you go learn about vectors, but I'll include it just in case:
The balls travelling at 45 degree angles have a horizontal component of momentum of X/2 and a vertical component of momentum of X/2 (or -X/2 for the one going downwards). This gives them a magnitude of sqrt((X^2)/4 + (X^2)/4) = X/sqrt(2). Since the horizontal components add to X, and the vertical components cancel due to opposite direction, momentum is conserved.-- those two balls inevitably took that momentum away from the cue ball's momentum, and, if conservation of energy is to hold, then rightward momentum has overall been reduced?
This is your mistake, as I described above, the horizontal components still add up to the original value. If you are confused by the talk about components, go learn about vectors, here is not the right place to try to teach that.
The point was that by chance you got the angles right, but you should have used energy conservation to determine the angles.(To determine the angles they will go at, you need to apply energy conservation, in this case with equal mass balls, opposing 45 degrees angles with the original ball coming to a complete stop is the right answer for a perfectly elastic collision.)
This sounds like what my example says (and then those two balls travelling in opposing 45 degree angles likewise hit two more balls each, which are in turn likewise positioned so they travel in opposing 45 degree angles to the trajectories of the balls which hit them). If you ddin't intend it to concur with my example, then could you please provide more detail, maybe a diagram?
Edit: I always forget to include the attachment...
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#336 by HMXHMX on 08 Dec, 2016 15:27
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Two important news announced publicly by Dave elsewhere.
First, the sad news:Quote from: rfmwguyPer request by Harold White, they will not be presenting a video by Paul March. Go figure...
By "they" Dave means the Space Studies Institute and by the "video" he means Paul's presentation at the Estes Park Breakthrough Propulsion Workshop on 21 September 2016.
Paul retired from Eagleworks at the end of September. Before or after the workshop?
The video will be available, but our disclaimer is it represents Paul's personal views and not NASA's. No JSC Eagleworks endorsement is expressed or implied. -
#337 by LowerAtmosphere on 08 Dec, 2016 16:20
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Excellent posts Keith Ness! This is precisely what I tried to clumsily suggest earlier in this thread. If you try to forget all the surface currents, impedance and atmospherics for a second and focus on radiation pressure: it is not equal along the length of the cavity!
(Pardon the missing Latex mathematical notation, writing on mobile so this will be quick and dirty)
Radiation pressure is a function of:
Intensity=(Emax)(Bmax)/area
Relative Power=(2I/C)*adjusted local Q
Now we consider one simple question: if Q is more or less constant along the entire cavity - ignoring dielectric situation and antennas - where will more reflections/absorptions occur per unit time? Assuming volumetrically equal loading and constant power it is trivial to see based on existing sims and experimental thrust results that higher E/B fields will generally occur towards the small end. If more momentum transfers to the small end than the large end it should accelerate in that direction. The kinetic energy is then slowly dissipated as heat.
However to confirm that this mechanism works we need experimental data comparing field extrema and wall heating.
Obviously meberbs and others will jump to say that this should not yield higher efficiencies than a photon rocket, but I ask: do photon rockets resonate/recycle photonic inertia yielding 2I/c many times per unit time/smaller area?
The more conical the resonant cavity the more imbalance there should be. This also means builders should aim for many robust high energy cavities with maximum recycling. Not to toot my own horn here but my earlier honeycomb carbon nanotube thruster sketch would incorporate both high energy densities per unit area, high recycling and decent (improvable) Q.
So why discourage the klystron canon approach of 100kw if it is done in short (tuned!!) pulses? According to warptech's formula you'd see lift-off for a relatively light cavity and that would shut the skeptics up rather fast
All this is congruous with what I believe Shawyer , TT and others are trying to explain. -
#338 by rfmwguy on 08 Dec, 2016 16:38
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This is great news. Perhaps I'll return to posting here more often someday. I've been elsewhere most of the time. Not really sure why, its just the way its worked out. Been mending some fences with those I've clashed with some time ago. Feel its time to move past that since the paper came out and we have an experiment to focus on rather than theory. As a "simple-minded" engineer, that seems to work better for me. I have no qualms about theory of operation, just as Lance said in his opening remarks, we have an experiment preceding theory and while uncomfortable to many, I enjoy this aspect.Two important news announced publicly by Dave elsewhere.
First, the sad news:Quote from: rfmwguyPer request by Harold White, they will not be presenting a video by Paul March. Go figure...
By "they" Dave means the Space Studies Institute and by the "video" he means Paul's presentation at the Estes Park Breakthrough Propulsion Workshop on 21 September 2016.
Paul retired from Eagleworks at the end of September. Before or after the workshop?
The video will be available, but our disclaimer is it represents Paul's personal views and not NASA's. No JSC Eagleworks endorsement is expressed or implied. -
#339 by Vesc on 08 Dec, 2016 19:48
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I have been away for a long time. Since Thread 7! And am getting caught up. I've seen many references to the Eagleworks AIAA paper and comments to the effect that it is published? But I've also read that it is due out in a December 2016 issue of an AIAA journal. I don't see any December 2016 issues yet on the AIAA website. Can anyone tell me me which AIAA journal this paper will be published in and when to expect to see the December 2016 issue? Or if there is already a link to the paper I would appreciate a reply with attached link.
If this has already been discussed my apologies to the group. I just waded through several hundred posts and didn't find that needle in this haystack. Sorry.
PS: Love the Estes Park conference photo. I could have identified Dr. Rodal and Michelle without attribution but no one else. Not even Paul March. Looking forward to the videos as they arrive. I'm a big fan of SSI... Have contributed to them in the past, probably should do so again....
