Posts Tagged ‘best college football uniforms 2014’

Zowie

May 18th, 2017

Zowie est une série de bande dessinée d’aventure fantastique créée par Christian Darasse et Bosse pour l’hebdomadaire Spirou à partir du no 2123 en 1978 jusqu’en 1984, avant d’en faire un seul album édité en 1983 par Dupuis dans la collection Carte Blanche.

En 2007, en tant que scénariste et dessinateur et toujours avec son complice pour l’encrage, Bosse reprend la série pour Dargaud.

Zowie est un garçon un peu turbulent, envoyé en pension lugubre où il découvre un livre magique qui le mène dans un monde fantastique.

Un matin, à Ryons-les-Airelles, en compagnie de ses parents dans un bazar, Zowie Duprèdubois choisit un vieux livre plutôt qu’un canif ou une toupie pour se distraire à la colonie des vacances.

Arrivés à l’institution Le Foyer, la mère rassure son fils que c’est un endroit idéal et que tout le monde y est gentil, comme le dit bien le pion Gaspard Latasse qui vient juste de s’approcher à eux : « Le Foyer, tout le monde est choyé ». Ses parents étant maintenant partis, le pion change d’apparence avec un petit rire sardonique au moment où la sonnerie annonce l’heure du déjeuner : il doit surveiller le réfectoire. Zowie, se trouvant seul avec sa valise et son vieux livre, monte jusqu’à l’entrée où il entend, au bout de l’allée water waist belt, le cri d’avertissement venant à la cantine. Les enfants s’y montrent aussi bien gais que désagréable et se moquent du pion piqué de colère inutile. Zowie, voyant tout cela, se rassure et s’apprête à s’asseoir sur une chaise, mais un jeune voyou nommé Loulou lui ordonne grossièrement de se tirer de là. Le pion a tout vu, tout entendu et, s’approchant au nouveau, lui prévient que « si on n’est pas assez débrouillard, on ne mange pas ».

Le repas terminé, Zowie, retiré de la cour de la récréation avec son ventre vide, se met à lire jusqu’à ce que Loulou et sa bande, Cachou et Pogo, cassent son ambiance tranquille. Loulou lui recommande de donner le livre. Ce dernier refuse net, ce qui provoque une bagarre. Alerté par Cachou, le pion arrive. Loulou dit que c’est Zowie qui a commencé. Mécontent, le pion ramasse le nouveau et l’amène chez le directeur. Ce dernier, d’une manière je-m’en-foutiste, comptant l’argent, lui demande de prendre ses responsabilités lui-même. Le pion décide alors que Zowie passe l’après-midi dans la cave remplie de poussière et de toiles d’araignées, tellement sombre que le victime ne peut lire… mais, ouvrant le livre, une lumière y surgit…

Bosse et Christian Darasse aiment travailler ensemble, tout en discutant d’abord le scénario avant que le premier en écrive tout au long parce que « ce n’est pas tous les jours drôle de se retrouver face à sa planche, sans personne avec qui échanger des idées ou parler de son travail. Nous avons donc conçu une façon de travailler, qui au début ressemblait à une partie de ping-pong ».

Pour réaliser les planches, c’est Bosse qui assume les crayonnés des histoires et Christian Darasse à l’encrage, une partie du travail qu’il estime extrêmement. Quant à la mise en couleurs, c’est le studio Leonardo qui s’en occupe et, depuis la reprise de la série en 2007, Benoît Bekaert qui « complète à merveille notre équipe. Il réalise des effets visuels extraordinaires ».

En 1978, le personnage est né de l’imagination de Bosse et de Christian Darasse qui partagent le scénario, même si, de temps à autre, cela suscite des difficultés en raison que l’un ne reconnaît plus la plume de l’autre. Tous deux passionnés de musique, ils décident ensemble de le baptiser Zowie en hommage de Duncan Zowie Haywood Jones, fils du chanteur David Bowie dont ils sont fanatiques.

Dupuis publie la première aventure de trente planches ayant pour titre Les Malheurs de Zowie à suivre dans Spirou no 2123 du pendant onze semaines.

Bien que la première aventure intitulée Les Malheurs de Zowie ne compte que trente planches, les éditeurs de Dupuis prennent la décision de reprendre les quarante-quatre planches de Le Pinceau de cristal pour les réimprimer en album souple, au numéro quatre de la collection Carte Blanche Spirou à….

Il sort en plein premier trimestre 1983.

En 1983, le réalisateur Wolfgang Petersen, ainsi que les producteurs de Constantin Film et de Warner Bros., a déjà commencé à tourner, en Allemagne, le film L’Histoire sans fin dont l’histoire raconte un jeune garçon qui emprunte en douce un livre intitulé L’Histoire sans fin dans une librairie et, au fur et à mesure qu’il avance dans la lecture du livre, il se retrouve lui-même faisant partie de la quête dont le but est de sauver le monde et les habitants du Pays Fantastique. La maison d’édition, avec prudence, avant de porter plainte contre la production américaine, songe à se renseigner un peu plus sur ce projet et apprend qu’il s’agit d’une adaptation d’un roman Die unendliche Geschichte de Michael Ende, publié en 1979 : « De nombreuses idées incluses au premier album de Zowie, s’y retrouvaient. Un gamin qui entre en possession d’un livre magique, se révélant être un passage vers un autre univers fait de fantaisie et de magie. L’inadaptation du héros par rapport au monde réel et particulièrement scolaire. La persécution du gamin par les autres élèves. Et même le Mange-Pierre, l’un des personnages centraux de notre récit, s’y retrouvait en gardant le même nom!. »

Les éditeurs de Dupuis demandent aux créateurs d’évoluer les aventures de Zowie. De toute évidence, Bosse et Christian Darasse sont surpris : « Notre éditeur a sous-entendu, avec prudence, que nous nous en étions inspiré de manière inconsciente. Il nous conseilla d’écraser, et de faire évoluer Zowie dans une direction différente que prévue. Il fallait abandonner l’idée d’exploiter le livre magique qui nous rapprochait trop du récit de Michael Ende. Dupuis craignait que ce ne soit la Warner qui, en final, nous fasse un procès ! Non seulement nous nous sentions lésés, mais on nous suspectait de plagiat en plus. Nous nous mettions à craindre, pour le coup, de devenir persona non grata dans le journal ».

Complètement désorbités par le fait que le personnage continue l’aventure sans son livre magique, la série s’arrête finalement sur la décision des référendums et des nouveaux rédacteurs en chef. Bosse se souvient encore que « le pire était encore à venir. Nous nous sommes rendu compte, des années plus tard, que la parution du premier tome de Zowie était antérieure au livre de Michael Ende ! Antérieure d’un an et demi, environ ! Nous ne pouvions donc pas en être inspirés. Par contre, l’écrivain, lui, l’aurait pu être de notre travail. Ceci dit, il est loin d’être certain que nous aurions gagné un procès face à la Warner. Mais bon, notre éditeur, à l’époque, aurait dû nous soutenir… »

Au début des années 2000, en plein véritable phénomène de la saga Harry Potter, c’est par hasard à l’enterrement d’une amie de Christian Darasse que le responsable éditorial de Dargaud, Yves Schlirf, demande à ce dernier de reprendre les aventures de Zowie avec Bosse. Convaincu, Christian Darasse en parle avec son complice de toujours qui raconte ensuite : « […] je n’ai pas été long à me décider. Lorsque l’on vous offre la possibilité de revenir sur projet qui, à l’époque best college football uniforms 2014, avait échoué à causes de pressions extérieures, on ne peut que sauter sur l’occasion. Le plaisir était trop grand : nous voulions montrer ce que nous aurions pu faire de ce personnage si on nous avait laissé les coudées franches. »

Les fidèles lecteurs de l’hebdomadaire Spirou découvrent, le , un nouveau personnage Zowie dans sa première aventure de trente planches à suivre Les Malheurs de Zowie au no 2123 jusqu’au no 2133, en mars 1979, dont la couverture du no 2124 montre Zowie en pleine surprise avec son livre jailli de lumière, avec une petite fille en bas disant « Ça, c’est Zowie, dessin par Darasse ». À nouveau sur la couverture du no 2152, le , où Zowie et sa copine Liza semblent fuir, débute ici Le Pinceau de cristal, une seconde aventure de quarante-quatre planches à suivre jusqu’au no 2170, en novembre. Comme l’annonce dans le précédent numéro, le blondinet revient sur la couverture no 2197 du avec un air soucieux derrière une épave abandonnée en second plan pour une troisième aventure à suivre Le Mystère du An Veskenn jusqu’au no 2210, en août. Dans la même année, à l’occasion du numéro Spécial Noël, le magazine s’offre un récit complet de quatre planches titré Joyeux Noël petit sapin au no 2225 du . Huit mois après, il se montre à nouveau sur la couverture no 2260 du où l’on voit accompagné de Loulou dans une ambiance verdâtre sous l’orage lançant de mystérieux éclairs vert, avec une accroche « Zowie, le cumulus néfastus attaque ! ». Il s’agit de la quatrième aventure de treize planches titrée Zowie contre le cumulus néfastus à suivre jusqu’au no 2262. Un an après, Zowie apeuré par deux robots projetant un rayon rouge est sur la couverture no 2314 du , présentant une cinquième aventure Le Démon de l’érébus de quarante-quatre planches à suivre jusqu’au no 2324, en octobre. Zowie fait sa dernière apparition avec sa bande sur la couverture no 2359 du , Safari Land est la sixième et dernière aventure de quarante-quatre planches à publier sur l’hebdomadaire jusqu’au no 2370, en septembre, même si quelques gags y apparaissent pendant un an.

RF resonant cavity thruster

December 1st, 2016

A radio frequency (RF) resonant cavity thruster is a proposed type of electromagnetic thruster in which electromagnetic radiation is confined to a microwave cavity and provides thrust to the cavity in a particular direction as the radiation reflects within the cavity.

This would be a type of reactionless drive, providing thrust from electricity without consuming a propellant. This appears to violate well-established laws of physics, such as the conservation of momentum; therefore most scientists believe such thrusters to be impossible. Many physicists have labeled them as “pseudoscience” best college football uniforms 2014. Despite this, inventors try to discover such drives, because if they exist they could support long voyages in space, where propellant is a primary limiting factor.

Roger Shawyer published a design with a tapered conical cavity, which he called the EmDrive. Guido Fetta later published a design with a pillbox cavity, which he called the Cannae Drive. A few groups of physicists have tried to build and test their own thrusters, based on the designs published by Shawyer and Fetta. Juan Yang at Xi’an’s Northwestern Polytechnical University (NWPU) initially reported thrust, but retracted their claims in 2016 after a measurement error was identified and an improved setup measured no significant thrust. Harold White’s group at NASA’s Eagleworks laboratories, which tests unusual rocket designs, has built and tested versions of these designs since 2011. In 2016, they observed thrust from a model they built, with a thrust-to-power ratio of roughly 1 mN/kW, which they wrote up in the Journal of Propulsion and Power.

This concept for a thruster drew attention in the 2000s when a few popular science magazines wrote articles about it as an “impossible” drive. There was particular criticism of misleading claims in the media that the drive had been “validated” by NASA following their reports of anomalous thrust in 2014.

Electromagnetic propulsion designs which operate on the principle of reaction mass have been around since the start of the 20th century. In the 1960s, extensive research was conducted on designs from ion thrusters that convert propellant to ions and accelerate and eject them; to plasma thrusters that eject plasma ions in a similar way using plasma currents. The plasma in a plasma thruster can be generated from an intense source of microwave or other radio-frequency (RF) energy and in combination with a resonant cavity, can be tuned to resonate at a particular frequency.

A low-propellant space drive has long been a goal of space exploration, since the propellant is dead weight that must be lifted and accelerated with the ship all the way from launch until the moment it is used (see Tsiolkovsky rocket equation). Solar sails, gravity assists, and propulsion by beams from the ground are useful specifically because they allow a ship to gain speed without propellant. However, these techniques do not work in deep space. Shining a light out of the ship provides a small force from radiation pressure, i.e. using photons as a kind of propellant, but the force is far too weak (for a given amount of electrical power) to be useful in practice.

A true zero-propellant drive is widely believed to be impossible, but if it existed, it could potentially be used for travel in many environments including deep space. As a result such drives are a popular concept in science fiction, and their very improbability contributes to enthusiasm for exploring such designs.

The design of such thrusters and the theories that attempt to explain how they might work are all matters of controversy, particularly the claims that it is an example of a reactionless drive, in violation of conservation of momentum.

John C. Baez, a mathematical physicist at the University of California, and Australian science fiction writer Greg Egan said that as of 2006 the positive results reported by Shawyer were likely misinterpretations of experimental errors.

Physicists Eric W. Davis at the Institute for Advanced Studies in Austin, and Sean Carroll at the California Institute of Technology, have said in 2015 that the thrust measured in both the Dresden University experiments and in earlier Eagleworks publications were indicative of thermal effect errors.

White’s 2014 conference paper suggested that resonant cavity thrusters could work by transferring momentum to the “quantum vacuum virtual plasma”. Baez and Carroll criticized this explanation, because in the standard description of vacuum fluctuations, virtual particles do not behave as a plasma; Carrol also noted that the quantum vacuum has no “rest frame” camelbak bottle belt, providing nothing to push against, so it can’t be used for propulsion.

White’s 2016 peer-reviewed paper invoked an idea called pilot-wave theory to suggest how the quantum vacuum could be used to generate thrust, however the paper noted that such interpretations are “not the dominant view of physics today.”

In 2001, Shawyer founded Satellite Propulsion Research Ltd, in order to work on the EmDrive, a drive that he said used a resonant cavity to produce thrust without propellant. The company was backed by a “Smart Award” grant from the UK Department of Trade and Industry. In December 2002, he described a working prototype with a total thrust of about 0.02 newtons powered by an 850 W magnetron. The device could operate for only a few dozen seconds before the magnetron failed, due to overheating.

In October 2006, Shawyer conducted tests on a new water-cooled prototype and said that it had increased thrust. He planned to have the device ready to use in space by May 2009 and was considering making the resonant cavity a superconductor.

New Scientist magazine featured the EmDrive on the cover of the 8 September 2006 issue. The article portrayed the device as plausible and emphasized the arguments of those who held that point of view. Science fiction author Greg Egan distributed a public letter stating that “a sensationalist bent and a lack of basic knowledge by its writers” made the magazine’s coverage unreliable, sufficient “to constitute a real threat to the public understanding of science”. In particular, Egan said he was “gobsmacked by the level of scientific illiteracy” in the magazine’s coverage, alleging that it used “meaningless double-talk” to obfuscate the problem of conservation of momentum. The letter was endorsed by mathematical physicist John C. Baez and posted on his blog.

Egan also recommended that New Scientist publish a refutation penned by John P. Costella (a data scientist with a PhD in theoretical physics). New Scientist editor Jeremy Webb responded to critics, stating,

“It is a fair criticism that New Scientist did not make clear enough how controversial Roger Shawyer’s engine is. We should have made more explicit where it apparently contravenes the laws of nature and reported that several physicists declined to comment on the device because they thought it too contentious… The great thing is that Shawyer’s ideas are testable. If he succeeds in getting his machine flown in space, we will know soon enough if it is ground-breaking device or a mere flight of fancy.”

New Scientist also published a letter from the former technical director of EADS Astrium, who stated: “I reviewed Roger’s work and concluded that both theory and experiment were fatally flawed. Roger was advised that the company had no interest in the device, did not wish to seek patent coverage and in fact did not wish to be associated with it in any way”, and a letter from physicist Paul Friedlander, who stated

“As I read it, I, like the thousands of other physicists who will have read it, immediately realised that this was impossible as described. Physicists are trained to use certain fundamental principles to analyse a problem and this claim clearly flouted one of them… The Shawyer drive is as impossible as perpetual motion. Relativistic conservation of momentum has been understood for a century and dictates that if nothing emerges from Shawyer’s device then its centre of mass will not accelerate. It is likely that Shawyer has used an approximation somewhere in his calculations that would have been reasonable if he hadn’t then multiplied the result by 50,000. The reason physicists value principles such as conservation of momentum is that they act as a reality check against errors of this kind.”

In 2007, the UK Department of Trade and Industry granted SPR an ITAR export licence to Boeing in the US. In December 2008, Shawyer was invited to The Pentagon to make a presentation on the EmDrive, then Boeing confirmed they wanted to licence the technology. The UK Ministry of Defence agreed to a technology transfer, and SPR designed, built and tested a Flight Thruster for use on a test satellite. According to Shawyer, the 10-month contract was completed by July 2010 and the Flight Thruster, giving 18 grams of thrust, transferred to Boeing. Afterwards, SPR never received a licence agreement and communication with Boeing stopped. Questioned on that matter in 2012, a Boeing representative confirmed Boeing Phantom Works used to explore exotic forms of space propulsion including Shawyer’s EmDrive some years ago, but such work has since ceased, stating that “Phantom Works is not working with Mr. Shawyer,” and adding that the company is no longer pursuing this avenue. No further details of Boeing’s Flight Thruster have been made public.

In 2013 and 2014, Shawyer presented ideas for ‘second-generation’ EmDrive designs and applications, at the annual International Astronautical Congress. A paper based on his 2014 presentation was published in Acta Astronautica in 2015. It describes a model for a superconducting resonant cavity and three models for thrusters with multiple cavities, with hypothetical applications for launching space probes.

In October 2016, a UK patent application describing a new superconducting EmDrive was published, followed by a first international version. Shortly thereafter Shawyer unveiled the creation of Universal Propulsion Ltd., a new company aimed to develop and commercialise such thrusters, as a joint venture with Gilo Industries Group, a small UK aerospace company designing and selling paramotors and the Parajet Skycar.

The Cannae Drive (formerly Q-drive), another engine designed to generate propulsion from a resonant cavity without propellant, is another implementation of this idea. Its cavity is also asymmetric, but is flatter than that of the EmDrive. It was designed by Fetta in 2006 and has been promoted within the US through his company, Cannae LLC, since 2011. Shawyer has said the Cannae drive “operates along similar lines to EmDrive, except that its thrust is derived from a reduced reflection coefficient at one end plate,” which he says would reduce its thrust. In 2016, Fetta announced plans to eventually launch a cubesat satellite containing a version of the Cannae Drive, which they would run for 6 months to observe how it functions in space.

Researchers working under Yang at the Northwestern Polytechnical University (NWPU) in Xi’an developed their own prototype resonant cavity thruster in 2008, publishing a report in their university’s journal on the theory behind such devices. In 2012-2014 they reported measuring net thrust in a series of preliminary tests, however in 2014 they reported that this had been an experimental error introduced by a power cable. In a revised study with an improved model, they reported that any actual thrust was too small for their setup to measure (less than 1 mN for a 230W power source).

All these devices use a magnetron to produce microwaves that are directed into a metallic, fully enclosed conically tapered high Q resonant cavity. They have a greater area at one end of the device and a dielectric resonator in front of the narrower end. They require an electrical power source to run the magnetron, but no actual propellant.

No mainstream scientific theory explains why such devices should produce thrust, however various attempts have been made to explain reported thrust measurements by the inventors and replicators.

The simplest explanation is that any thrust detected is due to experimental error or noise. In all of the experiments set up, a very large amount of energy is going into generating a tiny amount of thrust. Even the smallest stray signal – for instance from thermal or magnetic effects – could produce what looks like a thrust of that size. These experiments require more shielding from their environment than any of the experiments as of 2015 were able to provide, as each of those experimenters has noted. The strongest early result, from Yang’s group in Xian, was later reported to be caused by a large experimental error.

The 2016 Eagleworks paper discusses nine possible sources of experimental error. For example, one possible source of error comes from the thermal expansion of the thruster’s heat sink, which is offset from the device’s center of gravity; as it expands, it could cause the resonant cavity to move, producing erroneous results.

A similar explanation is that imprecisions in measurement, variation in measurement, or publication bias, have led to occasional positive observations with no statistical significance.

Shawyer describes the drive as not being reactionless, and instead that thrust is caused by a radiation pressure imbalance between the two faces of the cavity caused by the action of group velocity in different frames of reference within the framework of special relativity. He has self-published non-peer-reviewed papers describing how he believes the drive works: “[t]his force difference is supported by inspection of the classical Lorentz force equation F = q(E + νB). (1) If ν is replaced with the group velocity νg of the electromagnetic wave, then equation 1 illustrates that if vg1 is greater than vg2, then Fg1 should be expected to be greater than Fg2.” This statement makes two assumptions that Shawyer does not substantiate and that may explain the discrepancy between his predictions and those of conventional physics. For example he assumes that radiation pressure is the result of the Lorentz force acting on charged particles in the reflecting material. This is analyzed by Rothman and Boughn who point out that the standard theory of radiation pressure is more complicated than this simplified analysis suggests.

White’s NASA team suggests that their RF cavity may be an example of a quantum vacuum thruster (QVT or Q-thruster). A QVT is a theoretical system that uses the same principles and equations of motion that a conventional plasma thruster would use, namely magnetohydrodynamics (MHD), to make predictions about the behaviour of the propellant. However, rather than using a conventional plasma as a propellant, a QVT uses the quantum vacuum fluctuations of the zero-point field as the fuel source. If QVT systems were to truly work they would eliminate the need to carry any propellant, as the system uses the quantum vacuum to assist with thrust. It would also allow for much higher specific impulses for QVT systems compared to other spacecraft as they would be limited only by their power supply’s energy storage densities.

The 2016 NASA paper highlights that stochastic electrodynamics (SED) waterproof electronic case, allows for a pilot-wave interpretation of quantum mechanics, and that pilot-wave theory may explain how resonant cavity thrusters are able to produce thrust. Pilot-wave interpretations of quantum mechanics, as well as stochastic electrodynamics as a whole, are a family of deterministic nonlocal theories distinct from other more mainstrean interpretations such as the Copenhagen interpretation and Everett’s many-worlds interpretation.

A paper in EPL by Mike McCulloch, a Lecturer in Geomatics at Plymouth University, describes a possible method in which thrust from resonant cavities can be predicted using McCulloch’s controversial theory of quantization of inertia (MiHsC). McCulloch hypothesizes that inertia arises from an effect predicted by general relativity called Unruh radiation, that an accelerating object experiences black body radiation. Thus inertia is the pressure the Unruh radiation exerts on an accelerating body. At very small accelerations, Unruh wavelengths become so large they can no longer fit in the observable universe. When this happens, inertia is quantized. He pointed out possible observational evidence for this in the form of the otherwise unexplained jumps in momentum observed in some spacecraft as they fly past Earth toward other planets. While this model allows the device to create thrust without breaking Newton’s third law, it assumes that Unruh radiation is real, and requires the speed of light to change within the microwave cavity. This change in the speed of light is contrary to the central tenet of special relativity. Unlike some other hypotheses used to explain the device, McCulloch’s hypothesis is testable and McCulloch has suggested building a cavity where the length of the cavity is the same as the diameter of the small end, to cause the Unruh radiation to fit better in the small end, resulting in a reversal of thrust.

True reactionless drives are considered impossible for many reasons; for example, most reactionless drives are a form of perpetual motion machine. If thrust were produced without expelling momentum from the system in the opposite direction, the lack of momentum expulsion would make the device not only propellant-free, but a “reactionless” drive in the sense that it violates Newton’s Third Law and the conservation of momentum. Any such drive would require a new undiscovered physical law, which somehow had not been observed under any other conditions. The experimenters that have studied resonant cavity thrusters generally do not believe the drives are reactionless, and are trying to test one of the alternative hypotheses.

In 2004, Roger Shawyer reported seven independent positive reviews from experts at BAE Systems, EADS Astrium, Siemens and the IEE, however these are disputed. In a letter to New Scientist, the then-technical director of EADS Astrium (Shawyer’s former employer) denied this, stating

“I reviewed Roger’s work and concluded that both theory and experiment were fatally flawed. Roger was advised that the company had no interest in the device, did not wish to seek patent coverage and in fact did not wish to be associated with it in any way.”

In 2011, Fetta tested a superconducting version of the Cannae drive. The RF resonant cavity was suspended inside a liquid helium-filled dewar. The weight of the cavity was monitored by load cells. Fetta theorized that when the device was activated and produced upward thrust, the load cells would detect the thrust as change in weight. When the drive was energized by sending 10.5 watt power pulses of RF power into the resonant cavity, there was, as predicted, a reduction in compressive force on the load cells consistent with thrust of 8-10 mN.

None of these results have been published in the scientific literature, or replicated by independent researchers. They have been posted on their inventors’ websites.

In 2015, Shawyer published an article in Acta Astronautica, summarising existing tests on the EmDrive. Of seven tests, four produced a measured force in the intended direction and three produced thrust in the opposite direction. Furthermore, in one test, thrust could be produced in either direction by varying the spring constants in the measuring apparatus.

In 2008, a team of Chinese researchers led by Juan Yang (杨涓), professor of propulsion theory and engineering of aeronautics and astronautics at Northwestern Polytechnical University (NWPU) in Xi’an, Shaanxi, China, said that they had developed a valid electro-magnetic theory behind a microwave resonant cavity thruster. A demonstration version of the drive was built and tested with different cavity shapes and at higher power levels in 2010. Using an aerospace engine test stand usually used to precisely test spacecraft engines like ion drives, they reported a maximum thrust of 720 mN at 2,500 W of input power. Yang noted that her results were tentative, and said she “[was] not able to discuss her work until more results are published”. This positive result was over 100x more thrust per input power than any other experiment, and inspired other groups to try to replicate their work. However in a followup paper, Yang could not reproduce the 2010 observation and suggested it was due to experimental error.

In 2016, Yang’s team published a paper, in which they refined their experimental setup, using a three-wire torsion pendulum to measure thrust. They tested two different power setups. In one trial, the power system was outside the cavity: in this case, they observed a “thrust” of 8-10 mN. In a second trial, the power system was within the cavity, and they measured no such thrust. Instead they observed an insignificant thrust below their noise threshold of 3 mN, fluctuating between ±0.7 mN with a measurement uncertainty of 80%. They concluded that they were unable to measure significant thrust; that “thrust” measured when using external power sources (such as in their 2010 experiment) could be noise; and that it was important to use self-contained power systems for these experiments.

White’s team at the NASA/JSC Advanced Propulsion Physics Laboratory, also known as “Eagleworks”, is devoted to studying advanced propulsion systems that they hope to develop using quantum vacuum and spacetime engineering. The group has investigated a wide range of untested and fringe proposals, including RF resonant cavity thrusters and related concepts. In November 2016, a peer-reviewed paper summarising Eagleworks test campaign was published by the Journal of Propulsion and Power.

In 2011, the group began tests on its first RF resonant cavity thruster prototype.

In July 2014, the group reported tentative positive results for evaluating a tapered RF resonant cavity, similar to the EmDrive. Testing was performed using a low-thrust torsion pendulum capable of detecting force at the µN level within a sealed but not evacuated vacuum chamber (the RF power amplifier used an electrolytic capacitor not capable of operating in a hard vacuum). The experimenters recorded directional thrust immediately upon application of power.

NASA’s first tests of this tapered cavity were conducted at very low power (2% of Shawyer’s 2002 experiment), but a net mean thrust over five runs was measured at 91.2 µN at 17 W of input power. The experiment was criticized for among other things not having been conducted in a vacuum, to eliminate thermal air currents.

In early 2015, Paul March from Eagleworks made new results public, in which their team measured force with a torsional pendulum in a hard vacuum: about 50 µN with 50 W of input power at 5.0×10−6 torr. The new RF power amplifiers were said to be made for hard vacuum, but failed rapidly due to internal corona discharges. Without funding to replace or upgrade them, measurements were scarce for a time.

In 2014, Eagleworks later announced a plan to upgrade their equipment to higher power levels, to use vacuum-capable RF amplifiers with power ranges of up to 125 W, and to design a new tapered cavity that could be in the 0.1 N/kW range. The test article would be subjected to independent verification and validation at Glenn Research Center, the Jet Propulsion Laboratory and the Johns Hopkins University Applied Physics Laboratory. As of 2016, this verification and validation has not happened.

In 2015, Eagleworks conducted experiments in vacuum, with up to 80W of input power. They published the results in the American Institute of Aeronautics and Astronautics’s peer-reviewed Journal of Propulsion and Power, under the title “Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum”. This was released online in November 2016 football custom uniforms, with print publication in December. In the study, The researchers observed that the system they set up was “consistently performing with a thrust-to-power ratio of 1.2±0.1mN/kW”, and enumerated many potential sources of error.

The paper suggested that pilot-wave theory (a controversial, non-mainstream deterministic interpretation of quantum mechanics) could explain how the device produces thrust. Commenters pointed out that just because a study reporting consistent thrust was published with peer-review does not necessarily mean that the drive functions as claimed. Physicist Ethan Siegal commented on the paper, saying that the drive most likely does not violate conservation of momentum as this would “make physics fall apart” but rather that there is something else going on. He said that “Whether it’s new physics [or] the effect’s cause simply hasn’t been determined yet, more and better experiments will be the ultimate arbiter”. Physicist Chris Lee was very critical of the work, saying that the paper had a small data set and a number of missing details he described as ‘gaping holes’.

The same NASA test campaign evaluated a Cannae drive in 2014. They tested two versions: one device with radial slots engraved along the bottom rim of the resonant cavity interior, as required by Fetta’s theory to produce thrust; and a “null” test article lacking those radial slots. Both drives were equipped with an internal dielectric. The null test device was not intended to be the experimental control. The control device was a third test article involving an RF load but without the resonant cavity interior. Like the EmDrive tests, the Cannae drive tests took place at atmospheric pressure, not in a vacuum.

About the same net thrust was reported for both the device with radial slots and the null test device without slots. The experimental control without a resonant cavity interior measured zero thrust, as expected. Some considered the positive result for the non-slotted device a possible flaw in the experiment, as the null test device had been expected to produce less or no thrust based upon Fetta’s theory of how thrust was produced by the device. In the complete paper, however, Eagleworks concluded that the test results proved that “thrust production was not dependent upon slotting”.

In July 2015 an aerospace research group at the Dresden University of Technology (TUD) under Martin Tajmar reported results for an evaluation of an RF resonant tapered cavity similar to the EmDrive. Testing was performed first on a knife-edge beam balance capable of detecting force at the micronewton level, on top of an anti-vibration granite table at ambient air pressure; then on a torsion pendulum with a force resolution of 0.1 mN, inside a vacuum chamber at ambient air pressure and in a hard vacuum at 4×10−6 mbar (3×10−6 torr).

They used a conventional 2.45 GHz 700 W oven magnetron, and a small cavity with a low Q factor (20 in vacuum tests). They observed small positive thrusts in the positive direction and negative thrusts in the negative direction, of about 20 µN in a hard vacuum. However when they rotated the cavity upwards as a “null” configuration, they observed an anomalous thrust of hundreds of µN, significantly larger than the observed results. This indicated a strong source of noise which they could not identify. This led them to conclude that they could not confirm or refute claims about such a thruster. They plan future experiments with better magnetic shielding, other vacuum tests and improved cavities with higher Q factors to increase thrust.

Eric W. Davis, a physicist at the Institute for Advanced Studies at Austin, noted “The experiment is quite detailed but no theoretical account for momentum violation is given by Tajmar, which will cause peer reviews and technical journal editors to reject his paper should it be submitted to any of the peer-review physics and aerospace journals.”

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