OU from orbital physics, and some spooky stuff

[schuler]

Hi.

I would like to copy/paste about fuel less rockets (thruster might be a better term).

EmDrive (also Relativity Drive) is the name of a spacecraft propulsion system proposed, and reportedly developed, by Roger Shawyer.^[1] New Scientist ran a cover story on EmDrive in its 8 September 2006 issue.^[1] The device is a magnetron with a specially shaped, fully enclosed tapering resonator cavity whose area is greater at one end. The inventor claims that the device generates thrust even though no detectable energy leaves the device. The inventor proposes to use it as a spacecraft propulsion system that uses no fuel (other than electricity), and no reaction mass.^[2]
On his homepage^[3] the inventor claims that independent peer-review is under way. Chinese researchers claim to have validated the EmDrive technology, and created a working device.^[4][5] An English translation of the peer reviewed article is available from the inventor's website.^[6] Yang Juan, professor of propulsion theory and engineering of aeronautics and astronautics at the Northwestern Polytechnic University in Xian, claims in a peer reviewed journal to have built a model that produces 0.72 Newtons (0.16 lb.) of thrust from 2.5 kW of input power. By comparison, the NASA HiPEP ion thruster, intended for use on the JIMO mission but never deployed, requires 25-50 kW of power, delivers 0.46-0.67 Newtons of thrust, and relies on Xenon gas as a reaction mass.^[7] When the Xenon gas is depleted, the thruster ceases to function. It is claimed that the EmDrive, because it does not rely on reaction mass, would work indefinitely without any fuel other than electricity. Because the reaction mass typically forms 90% or more of the total weight of a spacecraft, a thruster that did not require reaction mass would represent a fundamental breakthrough in spacecraft design and propulsion.

Source for above quote is: http://en.wikipedia.org/wiki/EmDrive.

[schuler]

Hi Radical,
In another post, you said you can't do experimentation.

I would suggest buying a U$3 dollars gyroscope from China (free shipping) to play with. Gyroscopes are amazing.

Your posts are always welcome. Please keep doing

[fritznien]

your em drive sounds like lots of fun but it has a long way to go.
a better demonstration is needed be for it becomes accepted.
what about the energy calculations on a regular rocket?
are you going to dig deeper into it?
fritznien

[schuler]

Hi Fritznien,
Let's assume we have a rocket with total weight of 1002Kg. 2Kg are solid rocked fuel. The rocket burns 1Kg of fuel per second and each 1Kg of fuel produces 1000Newtons.

By having F=ma => a=F/m. The acceleration is approximately 1m/s².

Assuming an universe without gravity (makes calculation simpler), after the first second, the kinetic energy is:

v=1 => E=mv²/2 = 1001*1/2 = 500.5J

Another second passes, another Kg is burnt, another 1000N are produced (fuel consumption and force produced are constant along the time) and the final kinetic energy is:

v=2 => E=1000*4/2 = 2000J. Incredible. The first 1000N created 500J, but the second 1000N created extra 1500J.

What do you think?

[fritznien]

what i think is that you are missing half the story.
as the rocket speed increases the velocity of the reaction mass drops
with respect to the rest point. so the rocket gains more energy and
the reaction mass less. your observation is not new.
please see.
http://en.wikipedia.org/wiki/Oberth_effect