Martin Tajmar has a SpaceDrive project and plans to create an instrument so sensitive and immune to interference that it would put an end to the debate once and for all. Tajmar believes that studying the EmDrive and similar propellantless propulsion systems will require nano-newton instrument resolution.
He is making a new to torsion balance. It is a pendulum-type balance that measures the amount of torque applied to the axis of the pendulum. Tajmar’s team used a laser interferometer to measure the physical displacement of the balance scales. The new torsion scale has a nano-newton resolution and supports thrusters weighing several pounds, making it the most sensitive thrust balance in existence.
Forces claimed by potential propellantless propulsion systems like the Mach-Effect thruster or the EMDrive are in the µN or even sub-µN range. In this paper, an automated thrust balance design capable of measuring forces of 100 nN for thrusters with a maximum mass of 10 kg is described to test these claims. The torsion balance features an electromagnetic calibration method, adjustable magnetic damping and tilt control as well as electromagnetic shielding. All onboard electronics can be controlled wirelessly via an infrared module for serial communication. Power is supplied to the balance using three separate liquid metal feedthroughs: one for voltages up to 500 V and frequencies up to 200 kHz, one for high voltage up to 30 kV DC or AC, and one for high-frequency signals up to 3 GHz. The thruster can be rotated by 180° to measure three different thrust directions without breaking the vacuum and changing the setup in order to gain confidence and refute e.g. thermal drifts. The whole balance is controlled via a script language implemented in LabVIEW. We tested Mach-Effect thrusters provided by Woodward and our own built model exploring higher frequencies and mixed-signals that are believed to create significantly higher thrusters. Also a magnetostrictive version was built and tested. For the EMDrive, several different frequencies and setups (with/without dielectric insert, flat/spherical end caps) were tested. So far, only thermal drifts and no real thrust has been observed in all our measurements.