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#480 by TheTraveller on 08 Sep, 2016 14:02
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[sarcasm modus]
hmmmm....
I thought you said it wasn't magic, yet what do I see there ? ? ? "magic happens inside"
[/sarcasm modus]
Since when isn't software running around inside an embedded microprocessor considered magic? -
#481 by TheTraveller on 08 Sep, 2016 14:14
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I think a 2nd antenna would be effective in that you could see when the cavity starts storing energy.
Here is a bit of EmDrive Engineering 101.
Take a empty cavity. Apply a Rf 100Wrf signal. Monitor the Forward and Reflected power. It will follow a typical 5 x TC charge curve. IE the Forward power will start out at 0 Watts and slowly increase to full value after 5 cavity TCs. 1 TC being Qu / (2 Pi Freq). Likewise Reflected power will start out at 100W and slowly decrease to the min value as per the final VSWR.
Nothing new here. This is known accelerator cavity engineering as attached.
In fact you can measure the cavity Qu by monitoring the time the Forward power takes to rise from 0 to 63.2% of the final value, that time being 1 cavity TC (Time Constant).
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#482 by JohnFornaro on 08 Sep, 2016 14:24
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There was some discussion of the effect of drag on the Cannae cubesat. The chief assumption, if I'm correct was that the sat would be launched in a "typical" orbit of about a 23.5 degree inclination, and a 150 mile altitude, with about a 90 minute period.
Atmospheric drag on the sat is measurable, but it cannot be ameliorated by always keeping the sat solar array parallel to the orbital velocity vector. The satellite must rotate about its own axis about once every 90 minutes to keep the array pointed at the sun. This rotation will continue in Earth's shadow.
See the attached sketch.
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#483 by Peter Lauwer on 08 Sep, 2016 14:48
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Dear NASA Spaceflight EM Drive forum members,
A short introduction of myself and my plans. I am setting up a replication experiment of the EMdrive. Although I have learned already a lot from the reports, discussions, simulations, etc. you have presented on this forum (I am very impressed what has been done so far), I think I can use some advise now and then so that I can make a useful contribution in this field.
I am a physicist, living in the Netherlands, but not currently working in a field related to this topic (microwave technology or space technology). I have some experience with RF though (but mainly up to 500 MHz) and with the measurement of small forces.
The experiment:
• The forces will be measured with a torsion balance (in the horizontal plane),
• The RF will be rather low power (~5 W), battery-fed, remote controlled or programmed,
• All components will be mounted on the torsion balance arm,
• I will make a frustum that resembles the ones used by Brady et al. (2014),
• Preferably I will work in the range, say, 1.8 – 2.2 GHz (the upper bound is because I have a 6.7 GHz Agilent spectrum analyzer, so I can see at least the next harmonic signal),
• At normal atmospheric pressure (maybe in argon, later). The big vacuum vessel I have access to, cannot really reach high vacuum (indeed, the electric discharge in a bad vacuum…).
• I will very likely also use dielectric inserts in the cavities.
The torsion balance already exists. It uses optical sensors to monitor its position and a magnet-coil system to keep the position ‘fixed’ (so you can say it is not really a torsion balance, the wire is only used as low friction suspension). It was designed for research on other claims of anomalous forces, years ago. The resolution is of the order of 0.2 micronewton, but that will depend on the modifications I am making at the moment (a more compact setup, the damping, etc.).
Therefore:
• Forces in the rance 10 – 50 micronewton will be sufficient for this setup (but, of course, depending on the disturbing signals which the RF system might generate).
Schematically it will look like the attached scheme (I came to realize, though, that VCOs may not be stable enough to remain tuned at resonance and PLLs may be needed).
At the moment I am making my first cavities. Of cylindrical form, in order to experiment with coupling loops, surface treatment of the copper, etc.
I might first experiment with cylindrical cavities on the balance. If forces are observed that are of the same order as what you expect for the conical shapes (i.e., the ‘EMdrive signal’), it might not be useful to proceed.
I will keep you informed, but it may take a month or two before I have anything interesting to write. It is a lot of fun to work on this project, I have to say. I am rather sceptical about the reality of this phenomenon, but even if it turns out it doesn’t exist, I lear a lot and it is a nice technical/scientific challenge.
Cheers,
Peter Lauwer
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#484 by Peter Lauwer on 08 Sep, 2016 15:02
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One critical remark I should like to make is that when the force of an EM Drive is only a function of P, Q and the shape&dimensions of the cavity, an EM Drive would be a very simple system and would have been developed out by now. I have the impression that the confusion, e.g. the reported influences of dielectric inserts point at: 1) the positive results are either due to experimental errors, or 2) something more complicated is at work.
But that is nice: more work to do for the experimentalist. '-) -
#485 by FattyLumpkin on 08 Sep, 2016 15:22
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Assuming frequency is "dead on" to a given frustum, load time is nearly immediate (some argue less than one second, others less than 2 seconds). This not nearly enough time for thermal forces to come into the mix. Thrusting "should" ostensibly be immediate...once again this is when the frustum and RF being fed in are a match to one another. Later on RF heating of the cavity can create thermal lifting effects, and "warp" the frustum walls, thus sending it out of "tune". Is this not the reason PPL tech and or adjustable end plate are incorporated in many builds? As many have agreed here it's best to be able to tune your antenna, with maggie got's to physically tune the frustum. Traveller reminded me of this.
Thanks FL -
#486 by Bob012345 on 08 Sep, 2016 15:31
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Aren't thermal effects time delayed so you could separate those out? Shouldn't these forces persist for significant amount of time after switching the rf generator off?NASA tests: "For the EMdrive, the device that was tested here, thrust was consistently observed on the device to be between 30-and-50 microNewtons, giving us that 1.2 N/MW figure. But the limits of the measuring device’s threshold was just 10-to-15 microNewtons! In other words, these results may be consistent and interesting, but this isn’t as robust as anyone wants it to be." Source: http://www.forbes.com/sites/startswithabang/2016/09/02/nasas-impossible-space-engine-the-emdrive-passes-peer-review/#1be7fbba692c
Balloon effect has no effect on the resonant cavity, because cavity can leak air
The thrust obtain by NASA is consistent with the thermal balloon lift I have calculated in my previous post (38.33 micro N).
It is true, some people claim they debunked the hot air balloon theory but the thrust obtained by them is much higher than the one observed by NASA so likely they made some mistakes.
Worse. Now you have both air jet effect as well as hot air balloon effect.
Thermal effects can be separated out as will soon be shown.
Also using phase change wax, as Dave did, to store the thermal energy works very well, which allowed him to record a thrust of 18mN.
There seem to be a lot of time delays in the data of the just released Shawyer report. Does that worry anyone here? -
#487 by krio on 08 Sep, 2016 15:44
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Well, I'm still wondering how it should play out in theory for a pulse magnetron 200 kW source in a single 0.2 us pulse but at a small superconducting frustum (1cm - 4cm diameter)
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#488 by TheTraveller on 08 Sep, 2016 16:39
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Assuming frequency is "dead on" to a given frustum, load time is nearly immediate (some argue leas than one second, others less than 2 seconds). This not nearly enough time for thermal forces to come into the mix. Thrusting "should" ostensibly be immediate...once again this is when the frustum and RF being fed in are a match to one another. Later on RF heating of the cavity can create thermal lifting effects, and "warp" the frustum walls, thus sending it out of "tune". Is this not the reason PPL tech and or adjustable end plate are incorporated in many builds?
Yes? , No? I do want to make sure I've got this right. Thanks FL
The min Reflected power tuning system I developed was very manual and involved doing manual freq changes while observing Reflected power. As my amp has a 31dBm attenuator and inbuilt Forward and Reflected power outputs, it was possible to do the tuning at low power, step up the power a bit, recheck the tuning and step it up to full power without involving much heating. As the Rf amp has a master PA enable, it is possible to do very short pulses of Rf of say 30us and watch the Forward power climb as the Reflected power drops.
5 x TC cavity fill time for my commercial build is around 30us, so in effect it fills and discharges fairly fast.
With this tuning method, which avoids frustum heating while tuning, the frustum once tuned and the Rf power pulsed on for a few seconds, yes the thrust generation is immediate.
Physical tuning is only needed if the Rf source is not freq adjustable as is a maggie, so there you need to physically tune to the maggie freq.
I expect when I receive my 2 thrusters, the initial tuning will take a few seconds but will be done initially at low power and then adjusted, at full power, as the reflected power drifts off min.
This multi stage tuning approach is why I designed a variable attenuator as then initial tuning can be done at low power and not affected by thermal changes that occur at high power. -
#489 by TheTraveller on 08 Sep, 2016 16:51
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I will keep you informed, but it may take a month or two before I have anything interesting to write. It is a lot of fun to work on this project, I have to say. I am rather sceptical about the reality of this phenomenon, but even if it turns out it doesn’t exist, I lear a lot and it is a nice technical/scientific challenge.
Cheers,
Peter Lauwer
Hi Peter,
Welcome to the club.
I would suggest the EW copper frustum is not a good build to follow as it does not resonate in TE013 mode at 2.45GHz.
Having a working freq tracker that can lock to the lowest VSWR at the target freq and in the target mode is vital.
Build accuracy and high polish are critical as are antenna design, position and orientation.
You need to be able to model the frustum and check for resonance in the desired mode, which can be determined by observing the end plate eddy current patterns which are unique to each TMxy and TExy mode.
It is not easy to build a working EmDrive but as time progresses the basics of EmDrive Engineering 101 are starting to be understood.
Monomorphic runs a builders only forum at: https://www.reddit.com/r/TrueEmDrive/
I have one at: https://groups.google.com/forum/#!forum/emdriveresearch -
#490 by Tellmeagain on 08 Sep, 2016 17:45
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May I ask why doing freq control via a 2nd sense port is not effective? Thanks.
Another side of that question is how to sense the level of reflected power from the input port via a secondary sense port on the frustum?
Sort of like trying to control the rpm of an ICE engine via sampling C02 emissions in the exgaust pipe. Yes there is a relationship but it is not how to effectively monitor & control engine rpm.
But the purpose of high Q is related to the field strength in the cavity, and a second port is perfect to just sense that. VSWR, on the other hand, is indirect because it senses power loss, which is proportional to the square of field strength. You used a not so accurate analogy, but you did not answer my question. -
#491 by Rodal on 08 Sep, 2016 17:50
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Atmospheric drag on the sat is measurable, but it cannot be ameliorated by always keeping the sat solar array parallel to the orbital velocity vector
Incorrect statement. On the contrary, it is well known that atmospheric drag is minimized by minimizing the cross-sectional area perpendicular to the drag force.
Thus, the minimum drag orientation is indeed flying with solar array paralell to the orbital velocity vector. This is known in Aerospace Engineering as flying "edge on" or flying in the low-drag feathered position. Flying edge on significantly reduces drag (as it is easy to verify by calculation, since the drag is proportional to the cross-sectional area perpendicular to the drag force).
If flying a spacecraft with solar arrays on gimbals, in the edge-on position the alpha gimbal is fixed. If desired, the alpha gimbal could be removed to lower weight.
This is what was assumed in my calculations: edge-on flying, with no gimbal, the solar array being fixed to the Cubesat, as in Cannae's picture.The satellite must rotate about its own axis about once every 90 minutes to keep the array pointed at the sun. This rotation will continue in Earth's shadow....
No. There is no law that imposes such a solar-array orientation as the only option.
When designing a solar array orientation for a Low Earth Orbit (LEO) there are several options for orientation of the solar array:
1) Sun pointing
The spacecraft may maintain (if so desired) a fixed orientation with respect to Earth, and a gimbal (alpha gimbal) can be used to track the Sun as the spacecraft rotates in orbit. A beta gimbal (rotation around the longitudinal axis of the solar arrays) can compensate for variations in the angle of the Sun to the orbital plane.
This is not the only alternative.
You propose a more extreme version of the sun-pointing configuration where the solar-array is fixed to the Cubesat and hence the whole Cubesat has to rotate continuously in order to keep Sun-pointing all the time.
This is a flying configuration that produces a much greater drag force.
In addition, since you are using no gimbals, you have to rotate the whole spacecraft to accomplish your proposed Sun-pointing at all times. Thus, you propose, as the only choice available, a flying configuration that produces greater drag, and that in addition requires rotating the spacecraft.
If one calculates this, one arrives at the conclusion that flying with sun-pointing configuration at all times will require a thrust that exceeds the published claims for copper EM Drive. (The kind of EM Drive that Cannae is reporting will fly in this mission). (*)
2) Hybrid. For example Sun pointing during iluminated position of orbit, and edge on during eclipse (to minimize drag). During eclipse the solar array can be gimbaled edge on to the orbital velocity vector, which will require a rotation of ~70 to 75 degrees twice per orbital period.
For example, the ISS adopts a hybrid solar array orientation: it points the solar array at the Sun (and takes the drag penalty) when in light, goes into a perpendicular mode in the dark. The ISS "furls" its solar panels when in darkness.
3) Edge on during the entire orbit. This is the option that what was assumed to minimize drag in my calculations, since EM Drive's (assuming that they would work somehow) are very limited in the thrust/PowerInput available. This was made very clear in the calculations.
This is what was assumed: edge-on flying during the entire orbit, with no gimbal, the solar array being fixed to the Cubesat, as in Cannae's picture:
Flying with the solar-arrays "edge-on" means that the amount of power available from the solar arrays will be decreased. This reduction was explicitly taken into account in my analysis !
Flying edge-on during the entire orbit, besides minimizing drag, has the advantage that it keeps the spacecraft facing the Earth at all times, which may be beneficial for missions to monitor the Earth.
This is not an option that is impossible, or that I invented "out of thin air". It is a well-known configuration option.
See articles by G. Landis and C. Lu, (AIAA) and by Anigstein and Sanchez Pena (IEEE) on analysis of solar panel orientation in low altitude satellites.
You state that flying with the solar-arrays Sun-pointing all the time is the only option. This is not so. It is simple to run the numbers and show that the option you appear to consider as the only possible option (Sun-pointing) will require significantly greater thrust, and that according to published claims for a copper EM Drive (if it were to work as claimed) would not be able to overcome.
____
(*) As a minor detail, being picky, the sketch and absolutist demand for such a complete rotation once per orbit needs further consideration. As we all know, the Earth rotates around the Sun once per _year_ (the Earth's orbit). Hence, the sun rotates once per _year_ in an inertial reference frame tied to the Earth's orbit Not once per spacecraft_orbit_.
The ISS itself rotates once per orbit to keep one side always looking at the Earth (it has an "up" and a "down" side - the cupola, for example, is on the down side and always points at the Earth) and that means that its solar panels _counterrotate_ when the Sun is up.
Hence the Sun-pointing option, besides involving greater drag, involves a level of complexity that is undesirable for a smallsat mission like the one proposed by Cannae.
By contrast, the flying "edge on" or flying in the low-drag feathered position is much simpler, involving minimum drag, and complexity. -
#492 by Monomorphic on 08 Sep, 2016 18:36
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Monomorphic runs a builders only forum at: https://www.reddit.com/r/TrueEmDrive/
As a correction, I'm a moderator of https://www.reddit.com/r/QThruster/ not /r/TrueEmdrive/ -
#493 by FattyLumpkin on 08 Sep, 2016 18:42
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Peter, the NASA frustum operated best (force/watt) at TE012 (I don't believe TE013 was ever modeled or tried for). The sim of TE012 works well but with the antenna(s) in a different position.
NASA had difficulty operating their frustum inTE012 with the antenna in the original position on the side...(couldn't get more than 2.6 Watts into it at 1.8804 GHz + other modes close by).
If you want to keep everything the same in the NASA frustum TM212 is the way to go, but the Q is not nearly as high as with TE012. X_Ray just recently (a few pages back) showed some sims as to why TM 212 was much easier to stimulate than TE012. I'll go back and try to locate the specific page(s).
Attached is the NASA frustum 1st in TE012 and 2nd in TM212 (marked TM211) FL
These sims were performed by X_Ray. Thank you X_Ray
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#494 by tchernik on 08 Sep, 2016 18:47
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Roger said there would be a demo in 2017. Here he meant of a levitating EmDrive.
Meaning no disrespect, I'll believe it when I see it. -
#495 by johnatan warp drive on 08 Sep, 2016 20:11
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Even with the recent news on EmDrive I still can not find which UK Aerospace company is Mr. Shawyer co-operating with.
I would be much interested to find out. Any idea what company it might be? We know he cooperated with BAE Systems and Boeing. But I am just not sure which UK aerospace company it might be now. Can it be some that is well known for cooperation with the UK Defense Ministry for example?
Roger did say he was working on a military drone.
Unless one crashes, it might be a bit difficult to discover the manufacturer.
There is An UCAV technology demonstrator project underway !
TARANIS
http://www.baesystems.com/en/product/taranis
several companies involved as
QinetiQ , Rolls Royce , BAE Systems, are all British aerospace companies
They could be working on a VTOL version with emdrive ? -
#496 by JonB on 08 Sep, 2016 20:49
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First question, Is there a way to use constructive interference with multiple frequency gens and amps to increase the amount of power transmitted into the frustum? Obviously you would need to synchronize with a small margin of error.
Second question, does multi-phase (like your homes power) resonate at the base frequency? or does the phase shift screw all that up?
Thanks in advance. -
#497 by SeeShells on 09 Sep, 2016 00:28
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Even with the recent news on EmDrive I still can not find which UK Aerospace company is Mr. Shawyer co-operating with.
I would be much interested to find out. Any idea what company it might be? We know he cooperated with BAE Systems and Boeing. But I am just not sure which UK aerospace company it might be now. Can it be some that is well known for cooperation with the UK Defense Ministry for example?
Roger did say he was working on a military drone.
Unless one crashes, it might be a bit difficult to discover the manufacturer.
there is technology demonstrator project underway !
TARANIS
http://www.baesystems.com/en/product/taranis
several companies involved as
QinetiQ , Rolls Royce , BAE Systems, are all British aerospace companies
They could be working on a VTOL version with Emdrive ?
Hmmm no.
A little strange that where you would expect the exhaust from the rear it's just blacked out and looks solid. Am I not seeing it?
I remember in WWII they stuck fake propellers on the new jets to hide the fact they were jets.
Just saying. It's probable that it could just be a black screen or something.
Shell -
#498 by Prunesquallor on 09 Sep, 2016 00:29
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There was some discussion of the effect of drag on the Cannae cubesat. The chief assumption, if I'm correct was that the sat would be launched in a "typical" orbit of about a 23.5 degree inclination, and a 150 mile altitude, with about a 90 minute period.
Atmospheric drag on the sat is measurable, but it cannot be ameliorated by always keeping the sat solar array parallel to the orbital velocity vector. The satellite must rotate about its own axis about once every 90 minutes to keep the array pointed at the sun. This rotation will continue in Earth's shadow.
See the attached sketch.
It doesn't HAVE to keep a solar pointing attitude. It could have sufficient array area combined with batteries to accommodate the varying solar power input. It HAS to have some anyways to survive eclipsing.
Sent from my iPhone using Tapatalk -
#499 by RotoSequence on 09 Sep, 2016 00:49
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A little strange that where you would expect the exhaust from the rear it's just blacked out and looks solid. Am I not seeing it?
https://www.youtube.com/watch?v=nG-TMhvZ1pU?t=63
I remember in WWII they stuck fake propellers on the new jets to hide the fact they were jets.
Just saying. It's probable that it could just be a black screen or something.
Shell
Very unlikely, IMO. Taranis was always designed to fill the niche of low-observable, unmanned combat drone, with the same envisioned timeframes as the US' own programs, and aircraft systems integration is increasingly time consuming, especially in multinational endeavors. Packing in experimental propulsion technology that can barely be shown to work into a new combat air system that's already been in development for ten years would be an extra layer of complexity that would gravely endanger the whole program, and force them to find a new way to field any sort of drone based air combatant should the propulsion elements fail. With respect to the solid black bars, it looks like the video is censored. The exhaust system is something BAE's been particularly secretive about, presumably for classified infrared signature reduction features.
