New propulsion system

renormalised (Carl) · #1 13-09-2009, 03:01 PM

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 · #2 13-09-2009, 03:05 PM

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

renormalised (Carl) · #3 13-09-2009, 04:29 PM

Quote:

Originally Posted by TrevorW

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

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

Kevnool (Kev) · #4 13-09-2009, 04:50 PM

Another thing thats way over my head.
Cheers Kev.

garyp · #5 13-09-2009, 07:48 PM

Quote:

Originally Posted by Kevnool

Another thing thats way over my head.
Cheers Kev.

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

Are you keeping a count of the "things"?

I've given up counting.

Cheers

Gary

GeoffW1 (Geoff) · #6 14-09-2009, 02:33 AM

Quote:

Originally Posted by TrevorW

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

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.

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, 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.

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.

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

Cheers

Spanrz (Brett) · #7 14-09-2009, 09:26 AM

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.

renormalised (Carl) · #8 14-09-2009, 10:26 AM

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 · #9 14-09-2009, 08:05 PM

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 (Geoff) · #10 15-09-2009, 03:12 AM

Quote:

Originally Posted by GeoffW1

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

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

TrevorW · #11 15-09-2009, 10:05 AM

I took that as a typo

renormalised (Carl) · #12 15-09-2009, 10:18 AM

Quote:

Originally Posted by Starkler

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

It's a large, weak, light bulb

Baron von Richthofen (Vaclav) · #13 15-09-2009, 10:27 AM

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

renormalised (Carl) · #14 15-09-2009, 10:37 AM

Quote:

Originally Posted by Vars191

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

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 (Vaclav) · #15 15-09-2009, 10:46 AM

Quote:

Originally Posted by 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.

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 (Carl) · #16 15-09-2009, 10:59 AM

Quote:

Originally Posted by Vars191

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

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 (Vaclav) · #17 15-09-2009, 11:11 AM

Quote:

Originally Posted by 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.

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 (Carl) · #18 15-09-2009, 11:17 AM

Quote:

Originally Posted by Vars191

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

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 (Vaclav) · #19 15-09-2009, 11:27 AM

Quote:

Originally Posted by 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.

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 (Carl) · #20 15-09-2009, 11:33 AM

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.