New propulsion system

[renormalised]

Interesting site...heard about this before but haven't seen too much research on practical applications beforehand. Here's the site...

http://emdrive.com/

[TrevorW]

I wonder how much power would be needed to produce 1g thrust

[renormalised]

Plug the numbers into the equation that's given on the site:D

[Kevnool]

Another thing thats way over my head.
Cheers Kev.

[garyp]

Ahh yes Kev. I agree with your thoughts on the matter.

Are you keeping a count of the "things"?

I've given up counting.:P

Cheers

Gary:)

[GeoffW1]

Hi,

Well, it says in the link that they got a Q value of 6.8 x 1000000 for their design. This is way efficient enough to put the theory to the test.

Elsewhere it says that theory predicts a specific thrust of 333 mN/kW when the Emdrive is going at 3 km/sec.

So at that stage, to get 1g force (9.8 mN) you only need about 34 kW input, or a weak light bulb. :question:

Under the applications drop-down they say




"If the 700 W (dc) engine was used as primary propulsion for a 50 kg science probe, ........... due to the effects of equation 2 (http://emdrive.com/firstgenapplications.html), the thrust falls as the velocity increases, until .....a terminal velocity approaching 30 km/sec."





As far as I can make out, that terminal velocity, which is 0.01 % the speed of light, is the main barrier to getting anywhere fast. But propulsion without propellant!! Wow!! It is early days. :eyepop:



BTW you don't need to accelerate very fast to reach a good fraction of the speed of light generally. If you accelerate at just 1g (that is, you perceive your own weight normally) you would reach 50% the speed of light in 6 months. :driving:



That is an oversimplification, but this argument generally is why some quite weak sounding propulsion systems like solar sails have been proposed.

Good post Carl :thumbsup:




Cheers

[Spanrz]

That's it, just strap a microwave oven on the back of your car next time, tell em, you've invented the car propulsion system......
And it cooks food too.... ;D

However, I don't see this technology getting into our infrastructure, due to microwaves and people factor.

Interesting technology though. :D

[renormalised]

It is quite a slow terminal velocity, however 30kms is more than enough for cruising around the solar system...that's a little over 60000mph. At that speed it's 4hrs to the Moon (say 8hrs for slowing down) or 3.3 weeks to Mars at it's closest (say a month or so with slowing down). Not bad...a lot better than 6 months like they're talking about. You wouldn't even get into orbit at that speed (it's about 14000mph).

[TrevorW]

Thanks for doing the math

(I was thinking more along the Isp and Delta V values assigned to standard propulsion systems)

the potential of such a propulsion system is enormous.

A 1 megawatt reactor would be enough too power a very large craft nearly indefinetly

at 1 g a 10 year trip to Proxima Centauri would be possible

and more appropriate than wasting time on Mars

[Starkler]

Sorry you're out by a factor of 1000. 34W is a weak light bulb, 34kW could light up the MCG!

[TrevorW]

I took that as a typo

[renormalised]

It's a large, weak, light bulb:P:P:D:D

[Baron von Richthofen]

Its a lot of bull, what is the thrust?
It reminds me of the cold fusion scam years back:screwy:

[renormalised]

If you know enough physics to prove that, then do so. And if Cold Fusion was a scam, how come over 400 labs worldwide started to work on the principle after all the hullabaloo died down...and found the same results as Pons and Fleischmann did. It may not be "pure" fusion per se, but something is happening. There's a lot more to the Cold Fusion fiasco than what you've been led to believe, I can assure of that.

[Baron von Richthofen]

Cold fusion has been proven but It still remains the question what is the force that is giving thrust, throwing a lot of formulas at you still does not answer the question

[renormalised]

If you read the spiel, the thrust is produced by radiation pressure within the waveguide. It's much like a solar sail only in that instance it's photons providing the thrust.

[Baron von Richthofen]

Particle radiation thrust is very small you would get the same amount of thrust from a bank of LED (photons), its there but every small, if I was to make a 35KW block of high efficient LEDS I would get more thrust they would and be more efficient
Creating micro waves very very inefficient 50% to 75% at best

[renormalised]

Yes, but you'd need thousands of LED's to generate 35KW of energy. A decent sized magnetron from an industrial microwave oven can do that rather easily. Plus, it's not the initial thrust that matters, it's the cumulative effect of that thrust over time which produces the high velocities. Same principle works for an ion engine.

[Baron von Richthofen]

It would take 300000 LED elements, it could all fit on 3 square meters, I think the Hydrogen scavenger ion engine is the best option

[renormalised]

Well, these new engines are only in the very early stages of testing. A lot more needs to be done before they become viable. I think, for now, the ion engines are the way to go.

[GeoffW1]

:lol::lol::lol::lol: it is.

[GeoffW1]

Hi,

I got curious about this. It turns out the MCG has 1680kW of lighting. Another reference says 1800kW.

So if that was an Emdrive it would be about 53Kgf of thrust. Probably not enough to send the MCG aloft. ;)

Cheers

[renormalised]

No, but after 3 weeks, your ship would be getting along at a decent clip!!!:D

[TrevorW]

A read further apparently there are claims it can't work and is a fraud

A 1 giga watt power source potentially could produce 25,000,000 lbs of thrust

[renormalised]

That's why the British Government and EADS are funding the project... somehow I think those claiming fraud have an axe to grind, somewhere.

That's what they maybe quoting to make it sound as if it's too good to be true, however a simple look at the physics shows that it would never get to that much thrust simply because the Q value would breakdown at such high power ratings...the resonance effect of the waveguide cavity would collapse, using current waveguide technology. To produce and sustain that sort of thrust, the value for Q would have to be ridiculously high...10^100, or something like that. Almost perpetual motion, which is what I believe these detractors are using to criticise the work being done.

An engine with that size of power source might produce that thrust for something like 2 secs, but that's about it. It would grind to a halt really quickly...just couldn't sustain that sort of power output.