主题：【讨论】求教物理大牛:西工大在搞天顶星技术？ -- billhy

外链出处

Mr. Shawyer claims his new drive will put existing ion drives to shame. Rejected by the Australia, Britain, and U.S. firms, he's developing his ideas in China. (Source: New Scientist)

A prototype of the drive is seen here. It uses a tapered cavity to supposedly produce thrust. Despite scathing criticism in the research community, China is investing big in the technology, hoping it will give them a military edge. (Source: Wired)

China Building Electromagnetic Drive (Emdrive)

DailyTech has reported on plenty of exotic propulsion technologies. From plasma engines to laser engines, the field of space propulsion is full of quirky ideas, many with big financial backing from NASA. Thus it takes a really strange idea to stand out. The story of Roger Shawyer and his "direct electricity" rocket is such a story.

Roger Shawyer's began his career entirely within the system. He worked his way up through the ranks and eventually became a senior aerospace engineer at Matra Marconi Space (later part of EADS Astrium) in Portsmouth, UK. There he supervised the design of radar and communications systems. Mr. Shawyer even served as a consultant on the Galileo project, Europe's satellite navigation system.

Then he came up with an idea that many would call crazy.

He drew up plans for an exotic space engine unlike any the world had seen. It would use a relativistic trick, first envision by Allen Cullen in the 1950s, to convert electricity into microwaves, which would then provide a supposedly incredible thrust. At Astrium, his outlandish ideas were met with scorn. He recalls, "I was told in no uncertain terms to drop it. This came from the very top."

So Mr. Shawyer went rogue, leaving his cushy desk job to design his engine, the EmDrive on his own. Reportedly he succeeded. In September 2006, he announced he had created a 9 kg prototype which consumed 700 W of power and outputted 88 millinewtons of force. Then in May 2007, Eureka carried news that Mr. Shawyer claimed to have upped his rocket's capacity to 96.1 millinewtons on 300 W (an over 100 percent performance boost), and better yet the new rocket was capable of continuous operation and its microwave generator did not burn out like the last.

Mr. Shawyer claimed his device worked based on a tapered cavity. Microwaves bouncing inside this cavity would normally cancel out forces in Newtonian mechanics. However, Mr. Shawyer believed under Einstein's relativistic mechanics, the taper would cause force to build on one side. And he claimed to have proof of it. Further, by limiting microwave conversion to heat, by lining the cavity walls with superconductor, Mr. Shawyer said he could produce a 30 N thrust on a single watt, increasing the prototype's efficiency by nearly 100,000 times.

Criticism was quick to come, though. Mr. Shawyer's papers and prototypes had not been reproduced or peer reviewed, fueling skepticism. Worse yet, John Costella, a theoretical physicist and electrical engineer who works for the Australian Department of Defense, whose Ph.D. is in relativistic electrodynamics, the field that Mr. Shawyers research draws upon, blasted the drive in an article in the magazine New Scientist, after Mr. Shawyer submit a paper for it.

Professor Costella stated in his scathing review, "It is well known that Roger Shawyer's 'electromagnetic relativity drive' violates the law of conservation of momentum, making it simply the latest in a long line of 'perpetuum mobiles' that have been proposed and disproved for centuries. His analysis is rubbish and his 'drive' impossible."

Ostracized in the U.S., in Europe, and in Australia, Mr. Shawyer turned to a country with ambitious space goals of its own and a penchant to think outside of the box -- China. Satellite Propulsion Research (SPR), Mr. Shawyer's company, has worked out a lucrative new deal with the Chinese government to develop the tech. What's more, Chinese physicists assisting Sawyer claim they are developing theoretical simulations that will "prove" the drive works.

Mr. Shawyer recently was interviewed by Wired magazine's "Danger Room" column and stated, "NPU started their research program in June 2007, under the supervision of Professor Yang Juan. They have independently developed a mathematical simulation which shows unequivocally that a net force can be produced from a simple resonant tapered cavity. The thrust levels predicted by this simulation are similar to those resulting from the SPR design software, and the SPR test results."

He goes on to say that the Northwestern Polytechnical University (NPU) in Xi'an, a leading government controlled Chinese university is manufacturing a prototype of his device. Professor Yang confirmed this, stating, "I could confirm that our mathematical simulation gives the results Dr. Roger Shawyer told you. Now we are submitting our result to a journal. It is now under the consideration of the editor. We also developed a tapered cavity and are preparing an experiment which will be completed at the end of this year."

The new drive, if it indeed works, would not help with launching objects into space. What it would be useful for is in-space propulsion. Most sci-fi writers envisioned "sublight" engines, and the direct electricity drive would do precisely that. If the Chinese get it working, it will give them a distinct military edge in space. A flight to Mars might take only 41 days. Further, it will cut the weight and costs of satellites approximately in half, as satellites require heavy boosters to maintain orbit. In short, the drive would revolutionize much of spaceflight and give China the dominance it dreams of -- if it works.

Mr. Shawyer says he would like to deal with the U.S. as well, but says communications have died. He states, "the flight thruster program is on hold for the present. [O]nce the U.K. government had provided an export license for a U.S. military application, the major U.S. aerospace company we had been dealing with stopped talking to us."

Meanwhile he and the Chinese are awaiting the peer review of their research. And the real test will not be in the response, which has already evoked mixed opinions, but simply whether the prototypes work -- and whether China's expensive and radical gamble in one man's rebellious dream has paid off.