Patent US3322374A — Magnetohydrodynamic Propulsion Apparatus (Foundational MHD Patent)
Bibliographic Information
| Field | Details |
|---|---|
| Patent Number | US3322374A |
| Title | Magnetohydrodynamic Propulsion Apparatus |
| Inventor | James F. King, Jr., Winston-Salem, NC, USA |
| Assignee | Individual (James F. King, Jr.) |
| Filing Date | September 30, 1964 |
| Publication Date | May 30, 1967 |
| Status | Expired — Lifetime |
| Classifications | B64D27/34 (All-electric aircraft); Y02T50/60 (Efficient propulsion technologies) |
| Jurisdiction | United States (US) |
Abstract
The invention relates to aircraft propelled through interaction of magnetic fields upon electrically conductive fluids such as plasma surrounding the craft. The system creates a traveling magnetic field using polyphase-excited coils arranged along the craft's axis. As this field travels downward, it induces eddy currents in surrounding ionized air. These currents interact with the magnetic field to propel the conductive medium backward (downward), creating reaction thrust that moves the craft upward — a pure electromagnetic lift mechanism with no propeller, no jet engine, and no conventional aerodynamic surfaces required.
Claims (Summary)
Claim 1: A craft with electrically conductive coil means producing magnetic fields that induce eddy currents in the surrounding fluid medium, with the interaction of the eddy currents and the magnetic field creating propulsion by body force on the conducting medium.
Claim 3: A heavier-than-air craft comprising: ionization means at the top of the craft generating an ionized air annulus; an array of driving rings producing a moving magnetic field that "repetitively progresses from the top to the bottom" of the craft; the moving field inducing eddy currents in the ionized air annulus, and the J × B body force on the ionized air accelerating it downward, propelling the craft upward by reaction.
Claim 9: The craft of claim 3 wherein the driving rings are progressively larger in diameter from top to bottom, providing aerodynamic stability effects through the tapered field geometry.
Description / Specification
Operating Principle: Traveling Magnetic Field Drive
The apparatus generates a moving magnetic field using polyphase-excited coils arranged along the craft's vertical axis. The coils are driven in phase sequence such that the magnetic field pattern propagates downward at a controlled velocity. This is directly analogous to the operating principle of a linear induction motor, where the craft's axis replaces the stator and the surrounding ionized air replaces the rotor.
The moving field induces eddy currents in the ionized air surrounding the craft. These currents interact with the generating magnetic field via the Lorentz force:
f = J × B
where J is the eddy current density (A/m²) and B is the applied magnetic field (T). The resulting body force accelerates the ionized air downward; by Newton's third law, the reaction force propels the craft upward.
The thrust magnitude is governed by:
T = (σ × B² × v_s × A) / (1 + σμ₀v_s/k)
where σ is the plasma conductivity, v_s is the slip velocity between field propagation speed and fluid velocity, A is the effective cross-sectional area, and k is a geometry factor.
Key Components
| Component | Number | Description |
|---|---|---|
| Ionizer ring | 21 | Creates ionized air annulus using high voltage — provides conducting medium |
| Driving rings | 14, 15, 16 | Superconductor rings producing the traveling magnetic field |
| Pole piece | 20 | Ferrite core increasing magnetic flux density in driving ring region |
| Air-directing skirt | 23 | Conical deflector at bottom providing directional control and aerodynamic stabilization |
Ionizer Ring (Component 21)
The ionizer ring at the top of the craft applies high voltage to the surrounding air, creating a corona discharge that ionizes the air and produces the conducting plasma medium required for the MHD drive. Without pre-ionization, air at ambient pressure and temperature has insufficient conductivity (σ ~ 10⁻¹⁴ S/m) for useful MHD coupling. With corona ionization, the local conductivity can be raised to σ ~ 1–100 S/m, sufficient for MHD propulsion at magnetic field strengths achievable with superconducting coils.
Driving Rings (Components 14, 15, 16)
The driving rings are the polyphase coil array that generates the traveling magnetic field. The rings are made of superconducting material to eliminate resistive losses and enable the high current densities required for strong fields. The progressively larger diameters from top to bottom (Claim 9) produce a flared field geometry that:
- Increases the effective interaction area with the ionized air column
- Provides outward radial force components on the ionized air, stabilizing the plasma column
- Creates the aerodynamic stabilization effect analogous to a conventional stabilizer
Control Systems
Three directional control mechanisms:
-
Segmented ionizer ring — the ionizer ring is divided into sectors; by varying ionization intensity by quadrant, the local plasma conductivity (and thus thrust contribution) can be asymmetrically distributed, producing net horizontal force for lateral maneuvering.
-
Closed-loop directional coils in the skirt (component 23) — short-circuit loops in the conical skirt region can be opened or closed electrically, modifying the magnetic boundary condition at the skirt and deflecting the field pattern (and thus the thrust vector) in the desired direction.
-
Frequency modulation — the alternating current frequency driving the polyphase coil array determines the traveling wave velocity v_s; modulating frequency changes the slip velocity and thus the thrust magnitude without mechanical adjustment.
Prior Art Referenced
- GB830816A (1960) — Vehicle propulsion using superconductor solenoids (cited in the patent)
- US patents on electrostatic propulsion and plasma acceleration systems
Technical Classifications
- B64D27/34 — All-electric aircraft (power plant is electric motor with no thermal/combustion stage)
- Y02T50/60 — Efficient propulsion technologies for aircraft
Historical Significance
The 1964 filing date (published 1967) places this patent concurrent with the SR-71 (first flight 1964) and the full classified development period of successor programs at Lockheed's Skunk Works. US3322374A establishes that the US defense and aerospace community had formal IP protection on atmospheric MHD propulsion at this time.
The patent is the ancestor of the entire family of MHD propulsion patents documented in this Physics_Math archive:
| Descendant Patent | Jurisdiction | Year | Enhancement |
|---|---|---|---|
| CN111038740A (Track_7) | China | 2020 | Rotating ring coil array — spherical vehicle |
| RU2106287C1 (Track_8) | Russia | 1998 | 16-coil array + rim emitters — disc vehicle, dual-mode |
| US8006939B2 (Track_16) | US | 2011 | Traveling-wave surface implementation — Lockheed |
| RU2046210C1 (Track_14) | Russia | 1995 | Nuclear ionizer + coaxial electrodes — space operation |
| CN111114774B (Track_22) | China | 2021 | AC magnetic field × ion current — separate lift and thrust modules |
The 1964 filing establishes that MHD propulsion was known and protected as IP concurrent with the same era that produced the classified aerospace vehicles most associated with the "black programs" — raising the question of whether classified operational MHD-propelled vehicles were developed contemporaneously and simply not publicly disclosed.
Citations
- Google Patents: US3322374A
- GB830816A (1960) — prior art: superconductor solenoid vehicle propulsion
- Yamato-1 MHD submarine demonstration, Japan, 1992 (related later MHD demonstration)
Patent text compiled from Google Patents. Full original at the above URL.