US 2,949,550: Thomas Townsend Brown's Electrokinetic Apparatus Patent (Wire-and-Plate Thrusters, Discs and a Torpedo Body)

US 2,949,550, "Electrokinetic apparatus", is the patent in which Thomas Townsend Brown set out a wire-and-plate electrode arrangement for producing thrust from high voltage. It was filed on 3 July 1957 as application US669830A, granted on 16 August 1960 and assigned to Whitehall Rand Inc; the patent record lists it as expired. Where the patent explains the thrust, it does so as a reaction against the medium surrounding the device.

What the patent claims

Brown states that he has discovered a previously unknown electrokinetic phenomenon. Given a charged pair of electrodes in a dielectric medium, he writes, "a force is produced tending to move the pair of electrodes through the medium". The patent is presented as a set of devices that exploit this, from a bench demonstrator to self-propelled vehicles.

The twelve claims fall into two groups. The first six are for thrust-producing apparatus, and each specifies that the high voltage causes relative movement of an ionizable medium around the electrodes (five say "ionizable dielectric medium"; the claim covering the reversing switch says only "ionizable medium"). The claims that follow are framed more generally, in terms of relative motion between a body and the surrounding medium. The explanation and claims described here frame the effect as a reaction against the surrounding medium; none of them invokes gravity.

How it is said to work

The basic unit, shown in the patent's Figure 1, is easiest to picture as a thin flat sheet (the "body") with a wire stretched alongside its front edge, separated from it by a gap and held there on insulating supports, so that the two sit in a single plane. A high-voltage source is connected across them with the wire positive and the plate negative.

Why should that move? The patent's answer is a reaction force: Brown treats the device as something that pushes on its surroundings. Electrically charged particles of the medium are shoved rearward, from the wire's side of the gap towards and behind the plate, so the medium streams one way and the hardware is pushed the other, wire first. Only the heavy particles, atoms and molecules, count in this account. Electrons also change hands at the plate, but Brown dismisses their contribution because each has about a two-thousandth of the mass of a hydrogen atom.

A reader may be reminded of what is often called an ion wind. That label is an outside interpretation, not the patent's wording: its explanation speaks only of a medium.

The designs described

Every variant keeps the pairing of a small leading electrode and a larger body behind it. What changes from one to the next is the following.

• The size of the leading electrode. Brown's concern here is wasted effort at very high potential: he says sharp points and edges cause losses there that cut into the thrust. His remedy is a fatter conductor, rods or hollow pipes, once the voltage passes 125 kv. Below that figure a fine wire is acceptable, so long as it is stiff enough to keep its shape.
• More units, or a reverse gear. Figure 3 gangs several plate-and-wire units side by side, with all the plates on the negative lead and all the wires on the positive. Figure 4 gives a single plate a wire at both its front and rear edges and a switch that selects which one receives the positive terminal, so the push can be reversed.
• A vehicle shape. In Figures 5 and 7 the plate becomes a circular disc, thicker in the middle than at the rim, with the wire following only part of its edge (one claim specifies an arc of less than 180 degrees) and a fairing to round out the outline. Figure 8 does away with a separate plate and wire: in a torpedo-like body the conducting nose, preferably positive, stands in for the wire and the conducting afterbody for the plate, with an insulating section between them. Fins on the nose may reach back towards the afterbody as ionizing elements and may be movable for manoeuvring.
• A supply carried on board. The Figure 7 disc and the torpedo both house the high-voltage source inside the vehicle, in the disc's hollow centre and the torpedo's insulating midsection respectively.
• A supersonic proposal. The torpedo's nose ends in a needle point, and Brown says he believes the ionization it produces in the atmosphere would ease passage through the sonic barrier.

What was actually measured

The one performance figure given with these designs belongs to Figure 6, a tethered carousel: a pair of the disc devices hung from opposite ends of an arm pivoted at its midpoint, with the high voltage fed in through rotating contacts and brushes at the centre. The reported result is a speed of 17 feet per second at 50 kv.

Brown immediately qualifies this as an illustrative example and adds that "the speed of the vehicles increases exponentially with the applied voltage". No second data point is given to support that scaling. The account of the test also does not state the length of the arm, the size or weight of the discs, the current drawn, the electrical power consumed, or the thrust in any unit of force.

What the document does and does not show

Under this wiki's rule for reading patents, a patent is a claim document: it establishes that an application was filed, examined and issued, not that the device performs as described (see Patent as Evidence). Taken on its own terms, this one reports a tethered rotation at a single voltage. The account of that test does not say what medium it was run in, and the atmosphere is named only in the torpedo proposal. The self-contained disc and the supersonic torpedo are design proposals, and the sonic-barrier remark is expressly a belief.

What the patent does establish is how Brown himself framed the effect in 1957: thrust as a reaction against charged particles of the surrounding medium, driven from a small electrode past a larger one.

Connections in the patent record

The only earlier patent it cites is Brown's own US1974483A, "Electrostatic motor", with a 1930 priority date and published in 1934. Among the many later patents that cite it are Electronatom Corp's "Flying apparatus" (US3120363A) and "Ionocraft" (US3130945A), along with a long run of electrostatic air-moving and air-cleaning patents from Sharper Image and Kronos. The patent office classification, H02N11/00, is a catch-all for generators and motors not provided for elsewhere, a heading that also covers alleged perpetual-motion devices; the classification is an administrative label, not a finding about this invention.

Further reading

A 2003 Army Research Laboratory report reproduces figures and text from this patent, builds wire-and-foil devices of the same general kind, and finds the force independent of polarity; its attempts to estimate the force from ion motion are described in Force on an Asymmetric Capacitor: The 2003 Army Research Laboratory Lifter Tests and Why Their Ion-Wind Estimate Fell Short (Bahder & Fazi).

Martin Tajmar's 2004 review lists this patent among Brown's publications, quotes thrust figures from the "Ionocraft" patent that cites it, and reports a sealed-box test that found no net force beyond corona wind: The Biefeld-Brown Effect as a Misread Corona Wind: Martin Tajmar's Sealed-Box Pendulum Test and Its 10 µN Limit.

Marc Millis's 2004 NASA survey traces the Biefeld-Brown idea to Brown's 1928 British patent and judges its later variants, including a NASA-patented asymmetrical capacitor, to be ion-wind devices: Prospects for Breakthrough Propulsion From Physics: Marc Millis's 2004 NASA Survey and Its Verdict on Biefeld-Brown Devices, Lifters and Asymmetrical Capacitors.