D Tibbets wrote:A perhaps more detailed experimental description. One red flag is that the test article and a supposed null control both apparently produce thrust... which suggests either the test setup is flawed or the physics is confounding...
http://ntrs.nasa.gov/search.jsp?R=20140006052
Dan Tibbets
No, the NASA folks shot themselves in the foot with this unclear NTRS abstract, which is very misleading once you have read the
complete paper, as birchoff and I did. Birchoff is right, the paper is only $25 (EDIT:
complete paper now available freely here), and now it's very clear that even ArsTechnica only read the NTRS abstract and didn't download the complete paper before writing and publishing their biased
article. Very poor journalism.
The fact is (and the NTRS abstract does not explain this): Eagleworks tested one tapered (frustum) cavity, aka Shawyer's EmDrive; and two Cannae drives which are also asymmetric but different resonant cavities. The Cannae drive is said to work on a purported different principle than the EmDrive, according to its inventor Guido Fetta (a net Lorentz force imbalance of electrons upon top vs bottom wall of the cavity). According to this purported working principle, one Cannae drive had
radial slots on its rim as required by Fetta in order to produce net thrust, and the second Cannae drive didn't have those slits and was intended to be a "null test device". But the Cannae null test article… also produced net thrust (20 to 40 µN of net thrust depending of the forward or backward direction).
We're talking of
net thrust because of course the setup was also tested with a null 50 ohm load connected, in order to cancel the effect from the drives and detect any detect any spurious force due to EM coupling with the whole apparatus (which exists, at 9.6 µN) and this "null" spurious force was evidently subtracted from any thrust signal due to the drives then tested on the pendulum.
So the fact that the Cannae null test article produced a net thrust doesn't imply the experiment was screwed up. It rather showed that the radial slits required by Guido Fetta for propulsion are not the reason for the thrust, and another theoretical explanation is needed. Absolutely no news on the websites, including wikipedia, actually reports correctly this information.
We can go further by pointing another underestimated yet important fact of those NASA experiments: all tests articles (the EmDrive version, the Cannae drive version, and even the Cannae "null test" version) had a
dielectric embedded within. This is a hint for a different theoretical explanation involving EM fields, proper acceleration, mass fluctuation and dielectrics. Maybe
Mach effects (due to Mach's principle), as supposed by Woodward and Fearn within the GR theory, or within a scalar-tensor theory of gravity according to
Minotti. As for Sonny White, he talks about compressible quantum vacuum fluctuations, but there are flaws about this conjecture regarding the thrust magnitude observed.