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# Rotational effect ion engine

have the spacecraft rotate from light pressure like a radiometer then use the ion engines to make circularly motional ion ejection This turns the entire surface of the spacecraft to an energy panel whereas regular ion engines use electric
 (+6, -1) [vote for, against]

Photon pressure like on a radiometer is different from the photovoltaic effect that makes electricity

even so I imagine a rotating ion drive spacecraft could pick up much angular momentum from photon pressure with giant wings kind of like a radiometer

now you know the way a whirlygoround changes speed when you move around

I think using an ion engine where the ions are emitted with angular momentum as well as linear momentum could emit more energetic ions as the rotational energy of the spacecraft was used to move the ions

its like if you were tossing things to go ahead from a whirlygoround then if you rotated the things you were tossing the change of angular momentum would be a part of the thrust velocity of the tossed things

 — beanangel, Oct 07 2009

New Scientist ion engine http://www.newscien...ful-ion-engine.html
[beanangel, Oct 07 2009]

Is this idea based on a flawed understanding of the light mill?
 — loonquawl, Oct 07 2009

 If the things you are throwing (ions) have angular momentum, then they are taking some of your energy away with them.

What are you gaining?
 — Twizz, Oct 07 2009

Gyroscopic effects will make directional control something of a challenge.....
 — 8th of 7, Oct 07 2009

 The idea here, as I understand it, is that the rotational momentum of the spacecraft would be a reservoir of kinetic energy and the ion drive is a mechanism by which the rotational kinetic energy can be converted into thrust.

 The conversion (if this worked) would deplete the rotational energy. However in space it would be possible to impart a tremendous amount of rotational energy to a spacecraft in vacuum before sending it forth and then this energy could be used over time to augment propulsion by increasing the velocity and consequent thrust of emitted ions.

Very nifty. Probably difficult to model in small scale on earth because of friction and the difficulty in propelling a model by shooting things. Perhaps a skateboard propelled by paintball guns mounted on a gyroscope. With a given charge of CO2 and number of shots, does the model travel farther with a spinning gyroscope than with a stopped gyroscope?
 — bungston, Oct 07 2009

[+] for rotational to linear conversion
 — FlyingToaster, Oct 07 2009

I thought the idea was less about the storage of energy in a flywheel/spacecraft combo, but more about the harvesting of said energy by means of a light-mill, which is flawed in principle.
 — loonquawl, Oct 08 2009

 //light-mill, which is flawed in principle.//Is it ?

 on the same axis, a pair of counter-rotating flywheels; on the edge of each flywheel: variable-angle solar-vanes, ion engines and ion-deflectors.

 The range of movement for the ion engines includes being aimed at the ion-deflectors on the *other* flywheel.

 For basic solar-sail operation the vanes are flat, providing the maximum acceleration. For normal ion engine operation, the engines are pointed directly in the required direction.

 The flywheels are spun up in opposite directions by angling the solar vanes. They can also be be spun up by using the ion engines (though I'm not sure why you'd do this).

 To release the potential energy, shoot the ion-guns on each flywheel at the deflectors of the other flywheel, thus adding the speed of their relative rotation to the overall thrust.

(oh jeez I understand one of [beanie]'s ideas; is this a really good sign or a really bad sign?)
 — FlyingToaster, Oct 08 2009

Please keep in mind that in a vacuum, a light-mill runs very slowly. Backward.
 — lurch, Oct 08 2009

oh... so what I anno'd has nothing to do with the post then... (?) bugger.
 — FlyingToaster, Oct 08 2009

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