Propellantless propulsion, apparently.

I just read about this in New Scientist. Even if the article had gone into detail regarding the physics, I couldn't have followed it. A brief synopsis:

A method of propulsion has apparently been devised based on resonating microwaves in a waveguide. Microwaves are created within a chamber by a magnetron. No photons need to escape from the device. Rather, the resonating radiation imparts unequal forces on the different walls of the chamber as the photons bounce back and forth, causing a net force in one direction. It seems that the engine will be at least as effective as an ion drive, with the added bonus that it needs no propellant. It may even generate enough force to accelerate itself (and a good bit more) at 1G, allowing it to hover (with some well-chosen high-temperature superconductors). Seems to good to be true to me, but what do I know?

Here's somewhere to start. Please give me your opinions.

 

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DAMM IT... i had worked on similar ideas, only in my head... and hoped to pursue the research someday...

i guess, i wont be getting the nobel prize.

but im glad someone worked it out... it could change the destiny of mankind.

-MT

 

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I very much doubt that this works. Feels to much like a scam, or just plain honest error. I am willing to hold off judgement untill I see some solid math and some replication of the experiment though.

One other thing, iirc, superconductors don't work well at microwave frequencies.

 

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My opinion is that I should not tell them the right way to fix this up and should patent my idea and make them pay good money for it. It's too damn simple.

 

it is anything but simple.

-MT

 

So not much of a breakthrough then.

Wow wee

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So it will need to carry some kind of fuel to generate the energy to keep this cool yeah?

No not really, but it sounds a lot more exciting than it is to me.

 

My thoughts entirely, and when I have finished my chores I'll nip into town and pick up a copy of 'New Scientist' too. I can't see how it can work, to be honest.

The issue for it not working if it accelerates, stated in the linked article smells to me too. If it is an enclosed system, how does it know it's motion relative to an external frame of reference?

 

Actually, if i read this right, it's using radiation as propellent. Radiation does in fact have mass. You could theoredically power a spacecraft with a laser because although the mass of the photons are infintesimally small, they're moving at damn-close to C, giving a higher reaction to the ship and moving it forward.

But, assuming you had a ship with a nuclear reactor on it, and not a little nuclear sub reactor but one that powers several cities (huge reactor) of about a GW of power, and all of that power went into the laser/gamma laser/microwave (which wouldn't happen due to waste heat), you'd only be able to accelerate by 1m/s every few hours. A system like this makes up for ultra-small propellent use for ginormous power requirements.

But I don't know, maybe they're doing something different if they claim to be able to get a full gee of acceleration here using just solar power, which might be only a few kilowatts...

 

As near as I can tell from the linked article, the device isn't radiating. If it were based on radiation reaction, why bother with microwaves? A few incandescent light bulbs and a reflector will beat the pants off it both in price and weight.

They apparently think they have found a loophole in Newton's laws, but I suspect they're mistaken. I would sure like to know more about this though.

>> edit Here's a link to an older and somewhat more detailed article on Eureka. http://www.shelleys.demon.co.uk/fdec02em.htm

 

im so upset... its so simple.

with perfected resonating chambers, our world will soon be changed.

unless its all a scam, let us pray that it is not, for with such, all the starwars technology of floating vehicles could be ours.


IF IT IS A SCAM, i will be even more upset.

-MT

 

imaplanck, are you really so unimaginative? If this device can develop a thrust of 1G without expelling any propellant, all it needs is a power source. You could accelerate at 1G half-way to your destination, then decelerate for the remainder. It would open up the solar system.

 

Does it heat up burgers?

Really though, could they contain the radiation or would a geiger counter be going crazy in the cockpit?

 

It's just microwaves. Non-ionizing.

 

From the reference in first post:

"...Because of the difference in wave velocity, being higher at one end that the other, there is a momentum transfer. The result is a measurable net force from the cavity against its surroundings. ..."

The claim seems to be that the "faster waves" reflection off one end push harder than the slower ones reflecting off the other. That seems true, but to see how silly the device is as a propulsion system with no emissions, not even radiations (which would work) let us consider a similar system using BBs that make perfectly elastic collisions at opposite ends of a closed cylinder:

The only way the BBs can transfer more momentum to end A than end B is if the are going faster (like his waves) when they hit end A than when the hit end B. But the BBs rebounding from end A after elastic collision will have the same velocity as just before they hit end A (Best to think of all this in the reference frame where the ends A & B are stationary.) Thus, to make them hit end B later with less velocity they must pass thru some electromagnetic retarding field device in the center of the cylinder. Likewise those BBs bouncing elastically off end B need to be accelerated by this device to get them back up to the higher speed for striking end A.

Well, as Newton said quite while back; if the device in the center of the cylinder is applying a force to accelerate the BB going from B towards A and another force to decelerate them when going from A towards B, then a reaction force is acting on it also. The total force on the rocket is the sum of the net "end forces" and the forces acting on the central device, or zero total force acts on the rocket.

I suggest you not put your money into the IPO when it comes out. Let some other idiot do so.

 

No im just going on what you have posted here. Looking at that it doesn't seem remarkably impressive. Thats if it doesn't break any of the fundamental laws, which is of course suspect to begin with .

By what magnitude? You seem to be highly exaggerating the implications of this flying microwave oven.

 

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How much energy is required to drop the temperature to absolute 0. Can we even do that with our technology? How easy it is to get some Niobium?

Sounds kinda hopeless...

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They may want to use a Gaussian pulse.

 

we cannot get to absolute zero.... period.. so dont bother trying.
it would require to much energy.

we can reach 3-5 degrees above zero... which turns most things into superconductors....

noibium is availible, it is probubly to be used due to its strenght at that temp... since many metals become very fragile and brittle at that temp.

im not sure at what temp it become superconductive,, but if its over 7 degrees we are in buisness, since liquid nitrogen is readily avalible.

-MT