Search found 1130 matches

by 93143
Wed Oct 15, 2014 8:35 pm
Forum: News
Topic: The Impossible Thruster Works
Replies: 15
Views: 6228

Re: The Impossible Thruster Works

I'm intrigued by the apparent close correlation of McCulloch's predictions with the reported results. (Even if he's wrong, he could, like Shawyer, be right by accident.) Unfortunately I don't have the time to keep up with the thread...
by 93143
Sun Aug 24, 2014 8:51 am
Forum: General
Topic: How to defeat ISIL
Replies: 243
Views: 25193

Re: How to defeat ISIL

I guess there is an assymmetry - the Holy sites of all the book religions are in one place and this is and was dominated by Islam, so you get Christian incursions there in a manner that would not be reciprocated. [*facepalm*] http://en.wikipedia.org/wiki/Battle_of_Yarmouk http://en.wikipedia.org/wi...
by 93143
Sun Aug 24, 2014 1:44 am
Forum: General
Topic: For the same pricetag to mitigate climate change
Replies: 18
Views: 2205

Re: For the same pricetag to mitigate climate change

gas pressure laws suggest to me, sending atmosphere from Venus to Mars under its own pressure is quite possible. Yeah, it seems like a lot of gas pressure. But it isn't even enough to get a noticeable amount of gas out of Venus' gravity well (which is why it's still down there), and Mars is much fu...
by 93143
Sat Aug 23, 2014 12:59 am
Forum: General
Topic: For the same pricetag to mitigate climate change
Replies: 18
Views: 2205

Re: For the same pricetag to mitigate climate change

http://en.wikipedia.org/wiki/Conservative_vector_field

It doesn't matter what's happening near the mouths of the wormhole; the net result will be the same.

And what's this about an event horizon? A traversable wormhole shouldn't have an event horizon in the path of the matter traversing it...
by 93143
Thu Aug 21, 2014 10:42 pm
Forum: General
Topic: For the same pricetag to mitigate climate change
Replies: 18
Views: 2205

Re: For the same pricetag to mitigate climate change

Think of it this way - a wormhole is just part of space. Since gravity is a potential field (to first order, at least - I need to learn more GR), the difference in gravitational potential between two points is the same whether you traverse the distance through a wormhole or through normal space. And...
by 93143
Fri Jul 04, 2014 4:30 am
Forum: General
Topic: nanosat programming questions
Replies: 9
Views: 1167

Re: nanosat programming questions

I'm not so sure about that tether. It would produce thrust as well as power, neither one easy to predict exactly, potentially swamping the signal from the thruster.

Why not solar?
by 93143
Wed May 28, 2014 9:20 pm
Forum: News
Topic: SpaceX News
Replies: 2273
Views: 445899

Re: SpaceX News

Rocketdyne has been looking at selective laser melting for manufacturing RS-25 and J-2X parts. It works great; apparently it saved ~65% of the cost and ~97% of the manufacturing time for the first part they tried it on, and it ended up being a stronger part due to the lack of conventional welds.
by 93143
Tue Apr 22, 2014 2:26 am
Forum: News
Topic: SpaceX News
Replies: 2273
Views: 445899

Re: SpaceX News

The Zenit costs even less than the Falcon, but it's old Russian tech and can't compete so far as the efficiency needed to tail land. The RD-171 is substantially more efficient than the Merlin 1D, by 26-27 seconds (8-10% depending on altitude). Zenit doesn't have the dry mass fraction of Falcon, whi...
by 93143
Thu Apr 10, 2014 10:13 am
Forum: General
Topic: Go Navy!
Replies: 324
Views: 78931

Re: Go Navy!

I'd have thought they were already using liquid cooling, if heat dissipation is such an issue...
by 93143
Thu Feb 13, 2014 6:42 am
Forum: News
Topic: 20 years away, and always will be
Replies: 137
Views: 21253

Re: 20 years away, and always will be

CharlesKramer wrote:General Atomics predicted fusion was 20 years away (in the 1970s)

*ahem*
by 93143
Sun Feb 09, 2014 11:58 pm
Forum: News
Topic: Reaction Engines
Replies: 37
Views: 5341

Re: Reaction Engines

I messed up. The airbreathing net thrust is not Fgross - Mcap*U. It's Fgross - 2*Mcap*U, because Mcap is per nacelle.

Peak airbreathing net thrust is about 200 tonnes for the whole vehicle.

(Weird how the average was 200 tonnes before, but oh well...)
by 93143
Sat Feb 08, 2014 5:23 am
Forum: News
Topic: Recovery.Gov Project Tracker
Replies: 1822
Views: 866285

Re: Recovery.Gov Project Tracker

I see what you're saying but I respectfully disagree. The debate is over when a person's argument is shown to be untenable or impotent, and they don't offer new arguments without the same issues. This may be true in some cases. I was overly absolute earlier. But in the scenario you describe, it had...
by 93143
Wed Feb 05, 2014 9:42 pm
Forum: News
Topic: Recovery.Gov Project Tracker
Replies: 1822
Views: 866285

Re: Recovery.Gov Project Tracker

therefore, the other person wins. As far as I'm concerned, you don't "win" an argument until both sides honestly agree on what the answer is. If the debate doesn't resolve, you've both lost. This doesn't mean it's a total waste of effort to argue on the internet (even if you're both total...
by 93143
Wed Feb 05, 2014 6:31 am
Forum: News
Topic: Reaction Engines
Replies: 37
Views: 5341

Re: Reaction Engines

You don't actually have to fire a rocket engine in vacuum to test it. Everything downstream of the throat is supersonic (except for the boundary layer, which is pretty thin and dominated by the bulk flow), so pressure waves can't travel upstream in the bell, and the main combustion chamber has no wa...
by 93143
Wed Feb 05, 2014 4:05 am
Forum: News
Topic: Reaction Engines
Replies: 37
Views: 5341

Re: Reaction Engines

People were trying to come up with ways to flight-test (or simulate) SABRE. I was wondering what the problem with ground testing is, considering that it's supposed to be followed by a Y-plane or two even before any production prototypes fly.

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