NASA engineer's 'helical engine' violate the law of physics

 Rocket engines that don’t need propellant have been proposed before: this is an illustration of the EM-driveIllustration by luismmolina/iStock / Getty Images Plus

For every action, there is a reaction: that is the principle on which  all space rockets operate, blasting propellant in one direction to  travel in the other. But one NASA engineer believes he could take us to  the stars without any propellant at all.

Designed by David Burns at NASA’s Marshall Space Flight Center in  Alabama, the “helical engine” exploits mass-altering effects known to  occur at near-light speed. Burns has posted a paper describing the concept to NASA’s technical reports server.

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It has been met with scepticism from some quarters, but Burns  believes his concept is worth pursuing. “I’m comfortable with throwing  it out there,” he says. “If someone says it doesn’t work, I’ll be the  first to say, it was worth a shot.”                     

To get to grips with the principle of Burns’s engine, picture a box  on a frictionless surface. Inside that box is a rod, along which a ring  can slide. If a spring inside the box gives the ring a push, the ring  will slide along the rod one way while the box will recoil in the other.  When the ring reaches the end of the box, it will bounce backwards, and  the box’s recoil direction will switch too. This is action-reaction –  also known as Newton’s third law of motion – and in normal  circumstances, it restricts the box to wiggling back and forth

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But, Burns asks, what if the ring’s mass is much greater when it slides  in one direction than the other? Then it would give the box a greater  kick at one end than the other. Action would exceed reaction and the box  would accelerate forwards

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This mass changing isn’t prohibited by physics. Einstein’s theory of  special relativity says that objects gain mass as they are driven  towards the speed of light, an effect that must be accounted for in  particle accelerators. In fact, a simplistic implementation of Burns’s  concept would be to replace the ring with a circular particle  accelerator, in which ions are swiftly accelerated to relativistic speed  during one stroke, and decelerated during the other.

But Burns thinks it would make more sense to ditch the box and rod  and employ the particle accelerator for the lateral as well as the  circular movement – in which case, the accelerator would need to be  shaped like a helix.

Frictionless space

It would also need to be big – some 200 metres long and 12 metres in  diameter – and powerful, requiring 165 megawatts of power to generate  just 1 newton of thrust, which is about the same force you use to type  on a keyboard. For that reason, the engine would only be able to reach  meaningful speeds in the frictionless environment of space. “The engine  itself would be able to get to 99 per cent the speed of light if you had  enough time and power,” says Burns.

Propellant-less proposals aren’t new. In the late 1970s, Robert Cook,  a US inventor, patented an engine that supposedly converted centrifugal  force into linear motion. Then, in the early 2000s, British inventor  Roger Shawyer proposed the EM drive, which he claimed could convert  trapped microwaves into thrust. Neither concept has been successfully  demonstrated and both are widely assumed to be impossible, due to  violation of the conservation of momentum, a core physical law.

Martin Tajmar at the Dresden University of Technology in Germany, who has performed tests on the EM Drive,  believes the helical engine will probably suffer the same problem. “All  inertial propulsion systems – to my knowledge – never worked in a  friction-free environment,” he says. This machine makes use of special  relativity, unlike the others, which complicates the picture, he says,  but “unfortunately there is always action-reaction”.

Burns has worked on his design in private, without any sponsorship  from NASA, and he admits his concept is massively inefficient. However,  he says there is potential to harvest much of the energy that the  accelerator loses in heat and radiation. He also suggests ways that  momentum could be conserved, such as in the spin of the accelerated  ions.

“I know that it risks being right up there with the EM drive and cold  fusion,” he says. “But you have to be prepared to be embarrassed. It is  very difficult to invent something that is new under the sun and  actually works.”

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