NASA’s tests have a big problem – the control version that was to produce no thrust did produce thrust
The NASA report on the Cannae drive wasn’t much help either, since it only delved into the practicalities of testing one of the devices. At first glance, however, it looked quite interesting, stating, “Approximately 30-50 micro-Newtons of thrust were recorded from an electric propulsion test article.” If you push a bit further, it looks much less promising:
Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust. Specifically, one test article contained internal physical modifications that were designed to produce thrust, while the other did not (with the latter being referred to as the “null” test article).
In other words, the negative control in the experiment worked. Which means that the experiment as a whole tells you nothing. Clearly, the device (even when disabled) appears to produce a force. But Lee suggested a variety of ways that this could happen and indicated that there are ways to monitor the device’s operation to see if any of them play a role (for example, he suggested that a mass imbalance of as little as 3 mg could account for the small force the NASA researchers found. “All in all,” Lee concluded, “it will take a lot more information before we can judge whether the thrust is really a thrust or not.”
China built their own system and used different modelling to get theirs to work than the UK Emdrive
China is building their own EMdrive inspired offshoot systems. They do not make claims about the scaling or the improvements that they expect. The biggest claims are from Sawyer expecting massive gains when the Q is increased with superconducting chambers.
Net thrust measurement of propellantless microwave thrusters.
According to classical electromagnetic theory, this paper introduces a new kind of propellantless microwave thruster device for use in space propulsion. This device is able to directly convert microwave radiation into thrust without the need for any propulsion medium. The difference with traditional space propulsion devices is that this system means there is no need to carry a large propellant tank, and the problems of plume emissions polluting the space craft can be eliminated. The system comprises a frustum microwave resonator, microwave source, and load. The microwave source produces microwave radiation which can be input into the frustum microwave resonator and form a pure standing wave and electromagnetic pressure gradient. Thus, along the axial direction of the frustum microwave resonator, net thrust is formed. This article, based on the indifferent equilibrium principle, overcomes the weight and rigidity resistance of the thruster itself, and successfully measures the net thrust produced by the propellantless microwave thruster. The results show that: Based on classical electromagnetic theory, creating a propellantless microwave propulsion system can produce a net thrust; when the microwave source output is 2.45GHz, with a microwave power of 80-2500W, the propulsion produced by the thruster is located in the range of 70-720mN, and the total measurement error is less than 12%.
Roger Shawyer of British Satellite Propulsion Research Co., Ltd. (SPR Ltd.) conducted important research into propellantless microwave thrusters. Roger Shawyer called the propellantless microwave propulsion devices the “electromagnetic drive” (emdrive). In 2003, he developed the first emdrive. Its diameter is 160mm, and its microwave power consumption is 850W. Using a balance beam method, the obtained actual thrust value was measured at 16mN. In 2006, Roger Shawyer developed a second emdrive. Its diameter is 280mm, and its power consumption is 1200W. Using horizontal and hanging measurement programs to measure the thrust, the obtained actual thrust value was 250mN. In 2007, Roger Shawyer carried out dynamic testing in a low-resistance
suspended rotating platform. The results of the experiment were that when the second emdrive consumed microwave power of 1000W, thrust reached 287mN and the 100kg air suspension platform was accelerated to 2cm per second.
Northwestern Polytechnical University began to study the propellantless microwave propulsion in 2008, using classical electromagnetic theory to explain the source of thrust used in propellantless microwave propulsion devices. The theoretical feasibility of the device was discussed. Northwestern Polytechnical University also proposed a frustum microwave resonator design method based on electromagnetic value simulation analysis and experimentally tuned propellantless microwave propulsion. At the same time, the University designed and developed the first set of propellantless microwave propulsion devices in China.
Although the British carried out pioneering research work on the emdrive, the thrust measurement programs lack scientific descriptions. Furthermore, to date, the research paper has not been published in official journals. In China, scientific research was carried out from a theoretical and experimental basis on propellantless microwave propulsion devices. However, propellantless microwave thruster device net thrust measurement results have not been scientifically provided from an experimental perspective. This paper uses a nationally patented device – the rocket indifferent equilibrium thrust measurement device – to measure the propellantless microwave thruster net thrust. Thus further experimentally verifying the feasibility of the practical microwave propulsion device.
The principle of propellantless microwave thrusters
In the system shown in Figure 1, the microwave source transfers electrical energy into microwave energy and along the waveguide and circulator is transmitted to the frustum microwave resonator. When the frustum microwave resonator’s fixed resonant frequency and microwave output electromagnetic wave frequency are identical, the electromagnetic frustum microwave resonator resonant frequency forms an electromagnetic pressure gradient along the direction of the cavity, resulting in a substantial net thrust. The frustum microwave resonator is a sealed cavity enclosed by metal. When wave resonance occurs inside the cavity, the following important features occur: When not considering other energy losses, the only microwave energy loss caused to the frustum microwave resonator occurs at cavity wall skin depth; the frustum microwave resonator has an amplification effect on the electric field and magnetic field power. However, it is not in violation of the conservation of energy. According to Maxwell’s equations and electromagnetic wave energy flux density vectors, the overall electromagnetic field in the cavity will create electromagnetic pressure;if you select a suitable electromagnetic field distribution law, an electromagnetic pressure gradient is formed along the direction of the frustum microwave resonator. Dividing the electromagnetic
pressure along the cavity surface into surface integrals, the thrust produced along the frustum microwave resonator axial direction can be obtained.
Indifferent equilibrium thrust measurement devices verify that, based on classical electromagnetic theory, creating a propellantless microwave propulsion system can produce a net thrust; Net thrust measurement of propellantless microwave thruster experimentation shows that the direction of net thrust produced by the propellantless microwave thruster is from the frustum microwave resonator big end to the small end. The results are consistent with theoretical calculations. When the magnetron microwave source output is 2.45GHz, with a microwave power of 300-2500W, the propulsion produced by the thruster is located in the range of 160-750mN, and the total measurement error is less than 12%. When the microwave source output is 2.45GHz, with a microwave power of 80-1200W, the propulsion produced by the thruster is located in the range of 180-270mN, and the total measurement error is less than 12%. Using a microwave network analyzer and spectrum analyzer for measurement, it was discovered that this experiment’s frustum microwave resonator has an extremely narrow resonant frequency bandwidth, of only 0.0016GHz; furthermore, with the magnetron microwave source actual output power in this experiment, within this narrow frequency range, a non-linear change with the microwave output power is found. This leads to net thrust having a non-linear variation with microwave output power. However, spectrum data analysis shows that propellantless microwave thruster net thrust increases with microwave actual power. The results are consistent with theoretical calculations.