OT: Is this for real...

Good luck obtaining the required near-instantaneous changes of velocity with a solar sail. At best you might manage to _sloooowly_ spiral in.

Also, getting into a lower orbit using the Hohmann maneuver requires two *braking* impulses and no speed ups.

Jeroen Belleman

Well, I like to trust peer-reviewed literature. This points at an abstract for a conference talk. So, it's not yet ready for a public announcement.

Particularly, NASA testing found nonzero thrust, both on the candidate device and on a 'test dummy' device. So, it's possible that their apparatus is reading zero plus error, twice, and they aren't sure of the error scale. Not a scam (on the part of NASA, at least), but not a good solid technology ready to invest in.

If I've done my arithmetic right 15 kW of RF power with a narrow beam pattern should generate about 50 uN thrust just from radiation pressure. Now, having said this, it would help to have some details about the actual experiments. Too often this kind of thing turns out to be nothing more than bad science.

According to Wikipedia, there were two kind of drives tested: the EmDrive and Cannae Drive. It was only the Cannae drive that had non-zero thrust in the 'null' test article.

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the '50s and early '60s.

all, he seems unaware of his own.

t that he's never actually admitted to making a mistake, which could just b e vanity, but rather that his style of argument is rigidly based on the b izarre delusion that whatever he thinks has to be right. He never backs up even his silliest ideas with any kind of appeal to authority - Admiral Fish er could get away with "never apologise, never explain" as a tactic, but he had a rather more substantial reputation than krw can claim, and was right rather more often.

argue any longer that you aren't smart enough to know what Jack Daniels is. We all accept just how stupid you are.

Actually, it was Robert Baer who posted the "Jack who?" response. It's you who is functionally illiterate.

I'm well aware that it's a widely advertised - if marginally drinkable - US whiskey

It's regrettably difficult not to be aware of it's existence, like Kentucky Fried Chicken and a few of your other widely advertised national failings. I'm also aware that Popov invented radio in Russia - the likely source of your original dim-witted joke, which I was kind enough to ignore, rather th an treat with the contempt it deserved. No good deed ever goes unpunished. There is a better (but still not very good) joke in there, about the greate r Russian inventor - the one who invented Popov - but that would be out of your league.

Being rude about Chinese scientists for being Chinese is simply silly - the re are lots of them around, and some of them are competent. The Russians ha d Mendeleev long before they had Popov. They also had polywater (Boris Derj aguin) but then again we've had cold fusion.

but it takes orbital mechanics, rather than aerodynamics.

lly vector your solar sail to slow you down, converting your circular orbi t into a more elliptical one that does get you closer to the sun, but if yo u want to end up in lower circular orbit, you've then got to vector the sai l to speed you up, because a closer-in circular orbit calls for a higher or bital velocity.

ith a solar sail. At best you might manage to _sloooowly_ spiral in.

Near-instantaneous changes of velocity aren't required - they are just more economical. The article does go on to talk about effecting orbital changes with low thrust ion drives. The Hohmann manoeuvre is a mathematical ideali sation of reality, not some kind of prescription.

But the thrust vectors point in opposite directions.

Strictly speaking, you need to correct the direction of the velocity vector , which does change with time - simply "dropping" into a lower orbit does i ncrease your velocity, but not in the direction you need to make the lower orbit circular, so you need to apply the second episode of thrust in a dire ction which speeds up the satellite's tangential velocity while cancelling the in-falling velocity.

There are a very large number of ways of doing it - which one you choose de pends on what you actually want to do, and the means you've got to do the j ob.

...and you're too stupid to figure out that I said even you weren't stupid enough to make that statement but you had to argue the point. OK, you win. You are that stupid and continue to pound that point home.

acuum of space.

Ethoxyethane (which wasn't the ether that Jamie had in whatever he uses ins tead of a mind) is used as a recreational drug by some, and is sometimes us ed as a solvent by organic chemists. It's extremely inflammable, and sensib le people (like me) avoid it if they can. When I was a post-doc chemist at Southampton one of my neighbours set his lab on fire by knocking over a bot tle of ethyl ether, and spent six weeks in a burns unit getting fixed up af terwards.

I had a similar - if much more localised and less destructive - incident wi th a much smaller quantity of carbon disulphide (which is even more inflamm able)when I was a graduate student, and avoid both like the plague. Physica l chemists usually can.

Fancy stuff, a wonderful solvent and curiously attracted to oxygen in just the wrong way (assorted organic peroxides, yummy!). Guessing said bottle was on the old side, or wasn't checked regularly for contamination, or had some encrustations that wouldn't register otherwise.

It's not as explosive as some would hype it to be (not at all, when stabilized), but the downside is, it can be nearly that bad, and most unexpectedly so given the notorious sensitivity of organic peroxides.

Ever do the "barking dog" demo?

Tim

cky Fried Chicken and a few of your other widely advertised national failin gs. I'm also aware that Popov invented radio in Russia - the likely source of your original dim-witted joke, which I was kind enough to ignore, rather than treat with the contempt it deserved. No good deed ever goes unpunishe d. There is a better (but still not very good) joke in there, about the gre ater Russian inventor - the one who invented Popov - but that would be out of your league.

d enough to make that statement but you had to argue the point.OK, you win. You are that stupid and continue to pound that point home.

Sadly, you lack the wit to make your concession even vaguely entertaining. There's not a skerrick of new information in your response, and you've mana ged to use the word "stupid" three times in one paragraph. I'd encourage yo u to do better, but you do take care to remind us that you can't.

You *still* can't read. Figures. ...too stupid.

instead of a mind) is used as a recreational drug by some, and is sometimes used as a solvent by organic chemists. It's extremely inflammable, and sensible people (like me) avoid it if they can. When I was a post-doc chemist at Southampton one of my neighbours set his lab on f ire by knocking over a bottle of ethyl ether, and spent six weeks in a

t the wrong way (assorted organic peroxides, yummy!). Guessing said bottl e was on the old side, or wasn't checked regularly for contamination, or h ad some encrustations that wouldn't register otherwise.

The bottle wasn't old, but the guy was using a hair-dryer (with a brush mot or) to evaporate something off a filter-paper and a loop of cord had pulled the ether bottle off the bench and onto the floor, where it broke. Not a h appy combination. Ether's always stored in brown bottles to minimise photo- oxidation, and tends to come with added extra stabilisers if it's intended to be used as a solvent.

stabilized), but the downside is, it can be nearly that bad, and most unex pectedly so given the notorious sensitivity of organic peroxides.

Ether vapour is not as bad as hydrogen for forming explosive mixtures with air - as far as I know nothing is quite as bad as hydrogen - and this was a fire rather than a detonation, but quite a bad fire.

with a much smaller quantity of carbon disulphide (which is even more inflammable)when I was a graduate student, and avoid both like the plague. Physical chemists usually can.

Never heard of it. I did do the "clock reaction" for an Open Day demo once, and have used liquid nitrogen to make a tennis ball brittle. The more pyro technic things that you can do with liquid oxygen were rather above my pay grade at the time, though I have seen some of them done.

ntucky Fried Chicken and a few of your other widely advertised national fai lings. I'm also aware that Popov invented radio in Russia - the likely sour ce of your original dim-witted joke, which I was kind enough to ignore, rat her than treat with the contempt it deserved. No good deed ever goes unpuni shed. There is a better (but still not very good) joke in there, about the greater Russian inventor - the one who invented Popov - but that would be o ut of your league.

upid enough to make that statement but you had to argue the point.OK, you w in. You are that stupid and continue to pound that point home.

g. There's not a skerrick of new information in your response, and you've m anaged to use the word "stupid" three times in one paragraph. I'd encourage you to do better, but you do take care to remind us that you can't.

Come on - find a synonym for "stupid". You could do it if you tried really, really hard. "Krw" is obviously one, but there are others.

the one who invented Popov - but that would be out of your league.

I swear Sloman is a descendant of Babylon, cause that's all he does.

Jamie

Yes. And assuming a nuclear energy source, you'd get mc^2 for your mass.

If the quantum particles are to carry momentum, they can't just vanish again as they should have, so you can only get e/c^2 mass. Just exactly like throwing your fuel overboard, but with greater losses.

Colour me sceptical.

te:

te:

Kentucky Fried Chicken and a few of your other widely advertised national f ailings. I'm also aware that Popov invented radio in Russia - the likely so urce of your original dim-witted joke, which I was kind enough to ignore, r ather than treat with the contempt it deserved. No good deed ever goes unpu nished. There is a better (but still not very good) joke in there, about th e greater Russian inventor - the one who invented Popov - but that would be out of your league.

stupid enough to make that statement but you had to argue the point.OK, you win. You are that stupid and continue to pound that point home.

ing. There's not a skerrick of new information in your response, and you've managed to use the word "stupid" three times in one paragraph. I'd encoura ge you to do better, but you do take care to remind us that you can't.

You are probably right. There has been at city at Babylon since 2300 BC - w hich is 172 generations ago. That's long enough that at least one of our an cestors probably lived there.

Of course, what I type may strike you as babble because you didn't choose y our ancestors very carefully, and have failed to inherit the relatively sop histicated language processing mechanisms that most of us have - and you an d krw obviously lack.

Don't let it worry you - those of your descendants that survive will eventu ally lose that chunk of your defective genetic machinery and replace it wit h something better.

Most particles will pass straight through.

Thrust doesn't need to be directly away from the sun, with an angled reflector a portion of the thrust could slow the craft's orbit, gravity will do the rest.

The device in the original post does not work that way.

Sure. Then it's no longer a Hohmann manoeuvre.

Either way, the thrust is applied in the tangential direction, opposite to the direction of movement, at an instant where the radial velocity is nil. That's braking, in my book. Your last statement is wrong.

Jeroen Belleman