[AR] Re: NASA test of quantum vacuum plasma thruster
- From: Michael Clive <clive@xxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Wed, 6 Aug 2014 01:31:27 -0700
Thanks so much for this review. I was very excited, obviously, about this,
but upon reflection and the wisdom of people such as you, I have gained a
better handle on the experiment.
As someone who runs a test facility and often sees people screw up data
because they are not familiar with the equipment, your review rings very
true.
Dang.
Too bad.
Now I feel silly for getting all enthusiastic about this.
On Mon, Aug 4, 2014 at 7:38 PM, Willow Schlanger <wschlanger@xxxxxxxxx>
wrote:
> Hi John,
> Thanks for this review; it's a great wake-up call from someone who
> really read the paper. So, back to reality for us "space cadets," then?
>
> Willow Schlanger
>
> On 08/04/2014 07:10 PM, John Schilling wrote:
> > I was actually at that conference; didn't want to comment until I
> > had a chance to read the paper, but now I have so here goes:
> >
> > The team appears to have used a standard NASA-Lewis torsion balance
> > thrust stand. That thrust stand, which I have used extensively, is
> > good to about +/- 10 microNewtons when used in the steady-state
> > mode by an expert team. There is a resonant mode (look for a paper
> > by Lake and Dulligan) that can get down to +/- 1 uN or better, but
> > that isn't what was used here.
> >
> > Nor does the team that did this work appear to be thrust-stand
> > experts. There is relatively little discussion of that aspect of
> > their work, and what there is suggests that they did some things
> > right (e.g. comparison to a ballast load to rule out interference
> > from the power supply) and some things wrong (e.g. only a single-point
> > calibration). They do not cite a reference to their thrust measurement
> > technique, they do not give acknowledgement to any of the technicians,
> > and a quick literature search of their prior work does not suggest
> > great experience with the NASA-Lewis torsion balance thrust stand.
> > Absent such expertise, or even the recognition that such expertise
> > is necessary, errors of several tens of microNewtons are likely and
> > hundreds of microNewtons are not implausible.
> >
> > One thing they unambiguously did right, was to test the null-hypothesis
> > model of their "Cannae" thruster. Theory says that that with the
> > asymmetric groves you get ~10,000 microNewtons of thrust from 28 Watts
> > of electric power and without the groves you get zero thrust. They
> > tested both, on a thrust stand with error bars of a few tens of
> > microNewtons, and got ~50 microNewtons of indicated thrust.
> >
> > And made essentially no mention of this ever again, except to say
> > "We got Thrust! Yay Us!".
> >
> > Their subsequent testing of the truncated-cone thruster conspicuously
> > failed to make use of a null-hypothesis model. After repeatedly
> > showing about the same (lack of) performance as the "Cannae" thruster
> > in its first two operating modes, they conducted one single test of
> > the truncated-cone thruster in a third operating mode, demonstrated a
> > fivefold increase in thrust:power, and found that time and facility
> > limitations meant they had to terminate the experiments.
> >
> > Finally, they put forth a batch of conclusions that are entirely
> > unsupported by their own experimental data. It would have been bad
> > enough to have reported the single anomalously high truncated-cone
> > data point as the baseline and buried the null-hypothesis results.
> > Worse, is reporting only the Chinese experimental results (nearly
> > two orders of magnitude better than their own) and the theoretical
> > calculations which they did not perform and did explicitly disclaim
> > as beyond the scope of their paper, note that theory and experiment
> > (other people's) indicate a thrust:power ratio of 0.4 N/kW, and
> > proclaiming, "...and we also measured (mumble) thrust, so it's all
> > true and we can have manned missions to the outer solar system any
> > time now!"
> >
> >
> > They measured experimental error, and nothing more. And they set the
> > bar so low, with such implied authority, that we can now look forward
> > to years of dueling claims of "I built an EMdrive out of spare parts
> > and put it on a thrust stand I had lying around, and got microNewtons
> > of thrust just like NASA!", "So did I, and I got nothing at all!"
> > Did so, did not, ad infinitum.
> >
> > If theory and Chinese experiment really do validate claims of 0.4 N/kW,
> > then you really can build an enclosed metal box (batteries in the box,
> > to deal with the power-supply interactions Henry correctly notes) that
> > will visibly tilt a straight hanging pendulum. Do that, and get back
> > to us.
> >
> > Oh, and if you can build a reactionless thruster with a thrust:power
> > ratio of 0.4 N/kW and can't think of anything better to do with it
> > than fly to Uranus, you are an insanely myopic space cadet. I will
> > leave it as an exercise to the student how one would incorporate such
> > devices into a perpetual motion machine capable of providing clean,
> > free energy on a massive scale. It isn't trivially easy, but it is
> > almost certainly worth doing long before you build spaceships - and
> > this was presented at a "Propulsion and Energy" conference, so it
> > probably would have been worth mentioning.
> >
> > Well, except for the fact that the Energy attendees would have been
> > more merciless in their heckling; there's a long tradition of tolerance
> > in the "future flight" sessions of the AIAA Propulsion conferences.
> >
> > John Schilling
> > john.schilling@xxxxxxxxxxxxxx
> > (661) 718-0955
> >
> >
> >> Date: Sun, 03 Aug 2014 07:53:24 -0700
> >> From: Henry Vanderbilt<hvanderbilt@xxxxxxxxxxxxxx>
> >> Subject: [AR] Re: NASA test of quantum vacuum plasma thruster (was
> >> "Anyone
> >>
> >> G. Harry Stine made a sideline of looking into alleged reactionless
> >> drives. He knew how incredibly useful such a thing would be, he really
> >> wanted some such thing to be practical, so (typical of the man) he was
> >> rigorously skeptical. I went along for the ride on at least one of his
> >> visits, to a local guy who was trying to produce thrust mechanically.
> >> (As usual, strange things happened when you turned the rpm high enough
> >> just before the device flew apart, and as usual, there was no actual
> >> thrust involved.)
> >>
> >> Harry was actually very kind and polite in letting the guy know it
> >> wasn't real. Again, typical of the guy.
> >>
> >> (Enough reminiscing, cut to the chase.) I recall Harry explaining that
> >> he considered a convincing demo to be: Hang the device on the end of a
> >> pendulum in a vacuum, and demonstrate a repeatable constant displacement
> >> of the pendulum with power on versus power off.
> >>
> >> And it occurs to me to add, twenty years later, since presumably power
> >> of some sort is being routed to the device down the pendulum, set things
> >> up so the device can be reoriented relative to the pendulum and power
> >> feed, to distinguish between pendulum displacement due to the device
> >> actually thrusting along some axis, and pendulum displacement due to
> >> some power-on mechanical reaction of the power feed.
> >>
> >> Henry
> >
> >
> >
> >
>
>
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