[AR] Re: NASA test of quantum vacuum plasma thruster
- From: Willow Schlanger <wschlanger@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Mon, 04 Aug 2014 19:38:35 -0700
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 They do not cite a reference to their thrust measurement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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