IVO are apparently (finally!) launching their test system in a few hours, following several delays. If Andrew Aurigema, the coinventor, with Charles Buhler, of a system which he claims works on the same principle as the IVO device, is correct, the IVO system should work and in doing so, validate his own approach (he claims to have tested in vacuum of 10e⁻6 Torr and achieved ~62% thrust/weight ratio thus far). Both devices seeem to be based on exploiting the phenomenon of electrostatic pressure between asymmetric electrodes, which is subtly different from the "Biefeld-Brown" effect (that is to say, nothing to do with ion wind or Coulomb forces) but to my mind, it could be what Brown saw (if indeed he did!) if/when his devices moved in vacuum. When I first heard the term "asymmetric electrostatic pressure", I realised that these devices were essentially modern versions of a "Lafforgue thruster", as described in his 1991 French patent (autotranslation available at the site).
Jean-Louis Naudin did several experiments based on this patent about 20 years ago which seem to indicate the presence of an uncompensated unidirectional force (regardless of polarity) entirely based in mainstream physics (see for example this description). I think the conventional explanation is that the reactive force causes stress (and eventual breakdown) of the dielectric, but this seems to be an untested assumption. Another possibility is that it is somehow "pushing against" spacetime itself. The force generated is much smaller than the Coulomb forces, which might explain why it has been largely overlooked for propulsion purposes until recently. Andrew Aurigema is apparently quite open to visitors to his Florida lab, but does insist on an NDA.
