OT: Is this for real...

Falling sounds SO tackie...

The Casmir effect _IS_ a vacuum phenomena.

main objection is to its main advantage - that it produces thrust without using any fuel.

Actually, without using reaction mass, which isn't fuel in the sense of being an energy source.

a problem (although I have no idea whether this particular engine could work). The thing absorbs solar energy - and as we all know, energy has mass equivalent. So this mass gets ejected out the back,

Agreed.

Sadly, there is.

particular direction, and you get thrust without fuel.

Too true.

The key issue is that the thing shouldn't work at all, as physics is currently understood.

Solar sails depends on the idea that photons have mass and momentum, and that they interact with the rest of the universe.

Absolutely. This has the advantage that you are not just using the very small momentum from the light, but the much bigger momentum from all the other particles in the solar wind.

A solar sail is not an entirely unrealistic way to produce thrust away from the sun - but of course the thrust drops as you get further out, you need a very large, light-weight and strong sail, and you can only get thrust away from the sun. I don't know if it is possible to "tack" with solar wind in the manner of sailboats, or get an "aerofoil" effect.

It would not violate the conservation of momentum at all. If we briefly ignore incoming radiation, and assume the power source is onboard (say, from nuclear power), then it is just a matter of shining out light out one side in order to produce thrust. Momentum is conserved - light has a momentum, and that pushes the spacecraft the other way. If this new thruster uses some quantum effect to produce the particles ejected, then the same principle applies.

Technically, of course, such a system /would/ be using fuel - if there is no incoming external energy or matter (such as by solar energy), then the spacecraft will lose mass corresponding to the energy/mass ejected.

If it is getting energy from solar power, it is not a closed system.

It would perhaps be better to talk about "material propellant" rather than "fuel" - you will need some sort of energy supply, but no material propellant. Normal "ion drives" generate electricity by solar or nuclear power, and use that to ionise and accelerate a propellant gas. It is this gas that is avoided in light drives, or this new type of thruster.

I'm sure Slowman isn't even as stupid as you pretend.

As has been pointed out recently, it's tough to get "lift" in the vacuum of space.

Not that krw's opinion on other people's stupidity means much - after all, he seems unaware of his own.

Vacuum of space hmm, what about the ether ? :))

Jamie

main objection is to its main advantage - that it produces thrust without using any fuel.

Without any reaction mass. It does need energy. You shouldn't confuse the t wo functions of conventional rocket fuels - think about ion thrusters

no idea whether this particular engine could work). The thing absorbs sol ar energy - and as we all know, energy has mass equivalent. So this mass g ets ejected out the back, creating thrust. There is no need for any curren tly understood scientific laws to be broken or bent in the process.

g torch - absorb light energy from all around, shine it out the back in a p articular direction, and you get thrust without fuel.

- not much bigger than the push given by the sunlight falling on the sola r panels.

e area than converting the incident solar energy to electricity and then ba ck to light. ...not that I'm buying any of this fantasy.

small momentum from the light, but the much bigger momentum from all the other particles in the solar wind.

A reflective solar sail not only absorbs the momentum from photons, but als o the reaction momentum they impart as they bounce off - this allows you to vector your thrust. Solar wind just gets absorbed

om the sun - but of course the thrust drops as you get further out, you ne ed a very large, light-weight and strong sail, and you can only get thrus t away from the sun. I don't know if it is possible to "tack" with solar wind in the manner of sailboats, or get an "aerofoil" effect.

Tilting the solar sail allows you to vector your reflective thrust, essenti ally tacking. There's nothing analogous to the aerofoil effect. Vectoring y our thrust with or against your orbital velocity does allow you to change t he shape of your orbital ellipse, and raise or lower your orbit (in the end ) but the analogy with sailing isn't all that useful.

The sail doesn't have to be all that strong. Light-pressure is tiny, at lea st in our bits of this solar system

...on the other hand, I could be wrong.

Talk to Slowman about that.

An unfed troll gathers no podium. ...Jim Thompson

I know the difference. And the point of this engine would not need fuel for energy, as it has incoming solar energy, and it would not need fuel for propellant, as it uses some sort of quantum effects (which I don't understand, and am not convinced are real) to generate the thrusting particles. I don't know if the theory of this engine is real - but I know that an engine with the same effect can be made without breaking the known laws of physics, by simply using a light source for the thrust.

Solar wind is mainly charged particles, but also light. And just like light, the particles can bounce off (though with less efficiency) giving you a certain amount of directional control.

It is not the light that will damage the solar sail - it is the rest of the solar wind. The sail needs to be strong enough to handle that without significant wear.

um of space.

There's no ether.

If you want to use solar sails to get closer to the sun, you can do it, but it takes orbital mechanics, rather than aerodynamics.

If you start off in a more or less circular orbit, you've got to initially vector your solar sail to slow you down, converting your circular orbit in to a more elliptical one that does get you closer to the sun, but if you wa nt to end up in lower circular orbit, you've then got to vector the sail to speed you up, because a closer-in circular orbit calls for a higher orbita l velocity.

It's all a little beyond krw and Jamie who do seem to be our dimmest regula r posters - I initially typed "contributors", but thought better of it. "De tractors" would have come closer to the mark..

e '50s and early '60s.

l, he seems unaware of his own.

Krw lacks the wit to imagine that he could really be wrong. It's not just t hat he's never actually admitted to making a mistake, which could just be v anity, but rather that his style of argument is rigidly based on the biza rre delusion that whatever he thinks has to be right. He never backs up eve n his silliest ideas with any kind of appeal to authority - Admiral Fisher could get away with "never apologise, never explain" as a tactic, but he ha d a rather more substantial reputation than krw can claim, and was right ra ther more often.

I am sure he has plenty of that between his ears!~

Jamie

Slowman, once again, proves that he's illiterate. You don't have to argue any longer that you aren't smart enough to know what Jack Daniels is. We all accept just how stupid you are.