Fuel-less Space Drive May Actually Work, Says NASA
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30-07-2015, 10:43 AM
RE: Fuel-less Space Drive May Actually Work, Says NASA
Unless this thing is a box that does what it does without any kind of connection to something else, wired or wireless, then there MUST be a "fuel" supply of some kind to energize what gets done via the connection to the box. Whether storage batteries or starlight energy captured by photovoltaic arrays, it's still a fuel supply.

If the energy output of the box exceeds the energy input, then we're talking perpetual motion and the gadget is junk without even having to dissect it.

If the energy output of the box is less than the input, OK - so then the issue is, is the differential GREATER with this type of device than with any other type of engine? Does this produce more Gs of acceleration per watt expended than a lightsail, or other engine type that can draw its fuel from ambient sources rather than from a tank?

I haven't seen any of these questions addressed here, but the article from Hafnof does hew toward the thing being the junk of perpetual motion. I suppose all we can do is stay tuned.
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30-07-2015, 11:57 AM
RE: Fuel-less Space Drive May Actually Work, Says NASA
A clarification.... I think in this case - they're not talking "fuel" -- they're talking reactive mass.....

Fuel (like tetrahydrazine) is both the fuel, and the reactive mass....


Somebody correct me if I'm wrong...

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31-07-2015, 06:30 AM
RE: Fuel-less Space Drive May Actually Work, Says NASA
Currently the only ship design we've put into space that doesn't need to eject its own mass in order to accelerate is the light sail. It would be really really nice to diversify that portfolio, but it's still quite unclear whether this drive can do it or not.

The need for such a drive comes from the Tsiolkovsky rocket equation that fixes a relationship between the starting mass of a craft and its final speed. The actual performance of the drive is not as important as the possibility of a roughly constant mass craft that can accelerate for as long as it is able to generate power.

https://en.wikipedia.org/wiki/Tsiolkovsk...t_equation

Give me your argument in the form of a published paper, and then we can start to talk.
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07-08-2015, 09:12 PM
RE: Fuel-less Space Drive May Actually Work, Says NASA
I think it is a really neat concept, and I'd like for it to be real. But until the physics behind it is actually understood, it's up there with a lot of other crackpot stuff.

Hafnof, have we actually sent a craft to orbit with a light sail?
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07-08-2015, 09:29 PM
RE: Fuel-less Space Drive May Actually Work, Says NASA
(07-08-2015 09:12 PM)Fireball Wrote:  I think it is a really neat concept, and I'd like for it to be real. But until the physics behind it is actually understood, it's up there with a lot of other crackpot stuff.

Hafnof, have we actually sent a craft to orbit with a light sail?

http://sail.planetary.org/

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08-08-2015, 03:46 AM
RE: Fuel-less Space Drive May Actually Work, Says NASA
The second light sail craft is due for launch in 2016. The current missions are cube sats intended to prove and test the basic concept and technology. The last craft was only 10cm x 30cm at launch. The next launch will carry the names of my children to space Wink

https://www.kickstarter.com/projects/the...spacecraft

Give me your argument in the form of a published paper, and then we can start to talk.
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08-08-2015, 11:56 AM
RE: Fuel-less Space Drive May Actually Work, Says NASA
(07-08-2015 09:29 PM)RocketSurgeon76 Wrote:  
(07-08-2015 09:12 PM)Fireball Wrote:  I think it is a really neat concept, and I'd like for it to be real. But until the physics behind it is actually understood, it's up there with a lot of other crackpot stuff.

Hafnof, have we actually sent a craft to orbit with a light sail?

http://sail.planetary.org/

I meant from the ground to orbit, guess I wasn't all that clear. Probably the wrong question to ask, anyway. That link has a pretty cool satellite, using the light sail for orbital propulsion I've known of light sail propulsion out of/into a solar system as fiction (The Mote in God's Eye, by Niven and Pournelle), haven't kept up with the developments and didn't know that there were already light sail powered space craft in orbit. Cool.
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08-08-2015, 01:12 PM
RE: Fuel-less Space Drive May Actually Work, Says NASA
Light sails could never get you out of the gravity well into orbit, not the least because the massive sail would better serve as a parachute than a propulsor! But once there, it can incrementally increase your speed over a looooong period of time, since its "fuel" is inexhaustible. Accelerating at 0.01 G may not sound like a lot, but when you multiply that acceleration over a long period of time, you can get some pretty incredible speeds compared to, say, 10 minutes of blasting rocket fuel for a 3-4 G acceleration. Similarly, though they use (usually xenon) a propellant, ion engines work along the same principle of very slow acceleration for a very long time, magnetically catapulting ions out the back of the engine to produce a tiny acceleration at high efficiency. A solar sail works as long as there's light in large amounts.

The main issue is that it needs to be very light, strong, and collapsible in order to get up there to orbit at all.

So we've started with launching a very small one, to see if the actual numbers match predicted ones, and will proceed from there. It's all very exciting to me. Smile

This may help you understand.

"Theology made no provision for evolution. The biblical authors had missed the most important revelation of all! Could it be that they were not really privy to the thoughts of God?" - E. O. Wilson
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08-11-2016, 05:53 AM
RE: Fuel-less Space Drive May Actually Work, Says NASA
Here's an update:

Controversial Propellentless EmDrive is said to be undergoing tests in space on the Tiangong-2 station and US Air Force X-37B plane

And this:

New NASA Emdrive paper shows force of 1.2 millinewtons per kilowatt in a Vacuum and a low thrust pendulum and tests were at 40, 60 and 80 watts

I believe this experiment is the most rigorous to date, I thought I read that this has been submitted for peer review and accepted.

China has already tested this in space, so I'm thinking this is the real deal.

The article says that Roger Shawyer; the inventor of the EM drive, has been working with UK Ministry of Defense and the US Department of Defense for making a device for maneuvering in space.

So China, the US and UK are already working behind the scenes to use this technology.

This is frikkin' awesome! It's Star Trek technology! Thumbsup

Gods derive their power from post-hoc rationalizations. -The Inquisition

Using the supernatural to explain events in your life is a failure of the intellect to comprehend the world around you. -The Inquisition
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08-11-2016, 06:26 AM
RE: Fuel-less Space Drive May Actually Work, Says NASA
mN/kW? Laugh out load

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