The reversal test
University. · 2 min read
What it proposes
Before any propellantless thrust claim can be believed, the field needs a shared instrument and a shared protocol. That protocol exists, it is published, and it is unglamorous: turn the thruster around inside the vacuum chamber without opening it, and see whether the force turns around with it. A real thrust reverses. A hot cavity does not. This card is not a device, it is the standard every device in section 3 has to clear, and adopting it is the single fastest way to raise the quality of the whole field.
Who it is forPrecision-measurement engineersMetrologistsExperiment designers
Why the library suggests it
Martin Tajmar's group at TU Dresden built an automated torsion balance carrying a thruster of up to ten kilograms, reading its own deflection with a laser interferometer resolving one picometre, with a noise floor near eleven nanonewtons — far below the micronewton forces claimed — and with the whole experiment box able to turn through 180 degrees inside the vacuum chamber so one device can be measured forward, sideways and reversed without breaking vacuum. Running a Mach-effect thruster, a Dresden-built copy, a magnetostrictive version and four cavity configurations, every signal followed heat or drive current rather than direction (The SpaceDrive project — Thrust balance development and new measurements, 2019; the programme's statement of purpose is The SpaceDrive project – Developing revolutionary propulsion at TU Dresden, 2018). The rebuilt instrument resolves forces below a nanonewton, with the amplifier run off an on-board battery so no cable or liquid-metal contact can push on it, and its sensitivity floor sits at the light-pressure limit itself; its most valuable output is the artefact catalogue showing exactly how a heating cavity fakes a thrust that even reverses sign when the thruster is turned around (High-accuracy thrust measurements of the EMDrive and elimination of false-positive effects, 2021). The claim the protocol was built to test, in its most instrumented form — eight lead-zirconium-titanate discs at 39.3 kilohertz on about 170 watts, giving just over two micronewtons that reverses when the cage is turned — is Theory of a Mach Effect Thruster (2014).
The experiment or build
Build or borrow a balance with a nanonewton floor and a rotating mount. Then do what the Dresden authors themselves name as the open ground: the superconducting cavity, where the quality factor rises by orders of magnitude and nobody has yet looked. The settling measurement is thrust in nanonewtons per kilowatt, measured forward, sideways and reversed in one session, published together with the thermal transient and the drive current on the same time axis. A claim that cannot survive the sideways orientation is a thermal claim, and saying so plainly costs the field nothing and saves it years.
Where it stands
Published and peer-reviewed — the instrument, the protocol and the artefact catalogue are in the literature; the superconducting-cavity variant the authors name has not been run.
Take it up
- The measurement that settles it
- The settling measurement is thrust in nanonewtons per kilowatt, measured forward, sideways and reversed in one session, published together with the thermal transient and the drive current on the same time axis.
- What it costs to start
- University.
- The engineer it grows
- Anyone who wants the most transferable skill in this programme: designing the experiment that would prove you wrong.
What it rests on
- The SpaceDrive project - Thrust balance development and new measurements of the Mach-Effect and EMDrive Thrusters2019
- The SpaceDrive project – Developing revolutionary propulsion at TU Dresden2018
- High-accuracy thrust measurements of the EMDrive and elimination of false-positive effects2021
- Theory of a Mach Effect Thruster2014
Where it sits in the curriculum
Inertial mass reduction, the Navy patents and transmedium craftThe evidence ladderGravity control and superconductorsInertia and gravity from the vacuum