Roger Shawyer, the British inventor of the EmDrive, a exhaust-less thruster, has been interviewed by the IB Times. There is an article, with two videos at this link http://www.ibtimes.co.uk/emdrive-exclusive-roger-shawyer-confirms-mod-dod-interested-controversial-space-propulsion-tech-1586392
Here are some notes I took from watching the interview with Shawyer.
Eric Laithwaite claimed that a gyroscope could be used as a thruster. This got the UK Ministry of Defence interested who wondered if it could be used for missile propulsion. In the 1980’s he thought about it as a means of satellite propulsion. He started his own company where he developed the EmDrive. They developed a prototype that could produce 8 grams of thrust.
There was controversy when New Scientist published an article about the EmDrive in 2006. By 2008 his company was in meetings with the Defense community and at the Pentagon where he met with people from the US Air Force, NASA and DARPA. They then set up a contract with Boeing where they designed, built and tested a flight thruster which gave 18 grams of thrust for a satellite.
Boeing had prepared a license contract, and they were ready to sign, but everything went quiet and nothing has happened on that front.
He then started work on a superconducting thruster which can give more thrust. A UK Aerospace company became interested and also NASA. In 2014 NASA did research on a thruster that produced 10 mg of thrust. He says that the UK Ministry of Defense are interested.
On how it works, Shawyer shows an example of the EmDrive, which is a truncated cone. It has an input port for a microwave signal, and inside the thruster an electromagnetic wave propagates back and forth inside the cone.
He gives an explanation on how the EmDrive works:
“The velocity of propagation at the big end approaches 9/10th of the speed of light, while at the small end it’s about 1/10th of the speed of light, and it’s this difference in propagation velocity that causes a difference in the radiation pressure forces between the big end and the small end. So what you have is this thruster is actually producing a force in this direction [away from the big end] which causes an acceleration in the opposite direction, and this is just a simple example of Newton’s laws. What I would say is that the idea that EmDrive violates the laws of conservation of momentum is itself nonsense. Of course it doesn’t. It wouldn’t work if it did. All that EmDrive is a device for exchanging the momentum of the electromagnetic waves going up and down inside it, with the momentum of the thruster as it accelerates. It’s all actually elementary physics.”
He says that his company is meeting its milestones, and he sees EmDrive technology being used all over the world in the next decade. He thinks he will be able to make personal air vehicles which can land and take off vertically, that can take people anywhere they want to go. He thinks that one big application will be using it to make EmDrive craft that will be able to launch solar satellites to provide clean power to the world.
Roger Shawyer seems to be a fairly grounded, matter-of-fact engineer who seems to enjoy his work and who has big dreams about what it can do. There’s obviously a lot of interest from high powered entities in his work, and it’s really interesting to see ideas and inventions such as the EmDrive take shape.