Author Topic: Geek lite question  (Read 27927 times)

random axe

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Re: Geek lite question
« Reply #255 on: September 12, 2015, 09:38:36 AM »
Just put a sticker over the light.  A postage stamp works.

My paranoia is mostly based on my experience, which I assume is heavily influenced by curses.  Your mileage should vary.

mo

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Re: Geek lite question
« Reply #256 on: September 12, 2015, 02:15:38 PM »
My paranoia is mostly based on my experience, which I assume is heavily influenced by curses.  Your mileage should vary.

 :lol:

Quote
Just put a sticker over the light.  A postage stamp works.

The bulb is behind a grill, so the light is dispersed across the whole front. I assume the grill is part of the heat sink - I don't want to disrupt air flow. I could probably break the bulb by sticking something through the grill, but it's probably rigged to not run if the light doesn't come on, and that would probably void the warranty. It's fine the way it is, back there in the dust desert and wire jungle.
It's symbolic of our struggle against reality.

random axe

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Re: Geek lite question
« Reply #257 on: January 28, 2018, 12:17:01 PM »
SO I'm trying to figure out the effective range of a hypothetical (yes, only hypothetical) steam cannon.  I figure range will mostly depend on steam temperature and nozzle size, with some fiddling due to nozzle design.

I figure, hey, this is basically a steam rocket, so there must be web resources that will help me calculate how long the dangerous plume is from rocket exhaust, based on exhaust temp and so on.  But I can't find any.  The googles are not helpful.

Sidious

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Re: Geek lite question
« Reply #258 on: February 03, 2018, 06:09:17 PM »
It's not a very straightforward proposition to calculate that.  To figure out how much "work" you can get out of steam involves a lot of variables (pressure, temperature, entropy, saturation, enthalpy, et al) and a lot of thermodynamics knowledge.

Source: This is actually what I went to school for.  :lol:
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stormneedle

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Re: Geek lite question
« Reply #259 on: February 03, 2018, 09:10:42 PM »
And people think that it's the rockets that complicate things? (Well I did, never having looked into it at all.)
I'm generalizing from one example here, but everyone generalizes from one example. At least, I do.

random axe

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Re: Geek lite question
« Reply #260 on: February 04, 2018, 01:13:28 PM »
Thermo and fluid dynamics are complicated as shit to the likes to me, sure, but I'm talking about something simpler than work, per se.

I mean, like, if you took a model rocket, strapped it (firmly) to a table top, roughly how far behind it would be Danger Zone.

I'm not talking about a steam cannon that uses steam pressure to launch a projectile.  I'm talkin' 'bout a steam flamethrower, basically.  There's stuff you can do to try to make the gas stream more nearly coherent for a longer distance, but I have no idea what kinds of distance are in play. 

Can you project steam as far as you can project water through a roughly similar nozzle?  Diameter, if not shape -- a sort of aerospike shape is better, but the proportions for steam and water would be different.  The steam temperature / pressure can be supercritical before emission, but not so much afterward, but I don't know if the change of state induces so much turbulence that it's better to drop the pressure below supercritical first and then emit the steam, or what.

I was able to google a few mentions of industrial accidents at supercritical steam plants where a jet of steam escaping through a leak was apparently rather hazardous dozens of meters away, but they were all indoor leaks, so the area near the leak rapidly became a lethal steam room, anyway.  Not to mention what the noise must've been like.

So a steam cannon vaguely similar to, say, a fireboat's water cannon or a riot vehicle's deluge cannon . . . no idea.  At this point, I'd be happy with an order of magnitude ballpark guess.  There are limits to the pressure or you just get supercritical masses that will explode right at the nozzle when they contact the air, anyway, I think, but nozzle diameter will change flow rate.

A jet of superheated gas can travel a long way fairly coherently . . . upwards.  But I don't know about horizontally.  And I could just go the extra step to plasma, but then you've got electrostatic problems.  Going to self-sustaining toroids or laser-evacuated air channels and such is too SF for this application.

Dr. Leonard HmofCoy

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Re: Geek lite question
« Reply #261 on: February 08, 2018, 09:58:49 PM »
Man, I really hope this is for one of your fiction projects, because live steam ('live' meaning not condensing, so it is effectively invisible) is really fooking dangerous shit. I've never seen it travel more than a few meters because it cools off pretty fast in the air, but within that radius it might as well be a sci-fi disintegration beam. Darth Trent would know a lot more about this, but some of that information may be DUN DUN DUNNNNN classified ;)
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random axe

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Re: Geek lite question
« Reply #262 on: February 09, 2018, 11:11:18 AM »
Everything I do is fictional.  Also, the girlfriend wouldn't let me build doomsday weapons.


OK, the Musk Dragon is still bothering me.  How the fuck do the Falcon rockets economically carry the extra fuel they use for landing?  Isn't this whole carrying-extra-fuel-weight the basic problem of rocketry?  From what I hear, they don't use exotic boron fusors for thrust, or anything.  I never see anyone talking about this.

It seems ridiculous that he's magically produced rockets that can not only deliver payload to orbit super cheaply but that can also carry a crapload of extra fuel up there without being five times more expensive.  Is he just using a Saturn V-class booster where other people would use something a third as big with a third the fuel load?  And, if so, and if it works out like it seems to be working out, why didn't anyone else just do that?

Dr. Leonard HmofCoy

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Re: Geek lite question
« Reply #263 on: February 09, 2018, 09:28:53 PM »
I dunno, but I suspect that the high cost of rocket launches SpaceX is trying to break down is driven by the fact that all the work is done by a total of five corporations worldwide (plus three or four-odd states trying to build icbms) and they are all good old fashioned defense contractors. Who are still pulling the million dollar toilet seat gag on the taxpayers to this day (read up on the new Air Force One). I suspect they are silently colluding to keep prices high, as they do with every bit of military hardware they supply. As for the landing fuel, they just have less payload on those launches. Easy. Keep in mind that the rocket first stage weighs essentially nothing compared to it's launch weight - burned off almost all the fuel, got rid of the second stage and the payload, it's light. Hell, they're even recycling the payload fairings. That's amazing. I had no idea they were doing that.

I mean, compared to the DOD, NASA squeezes the blood out of every single penny they touch. And they are slow and expensive in rocket development because a) manned spaceflight costs more (didja notice Elon mentioning that the Falcon Heavy would not be used for manned missions? HMM) and b) politics, meaning they never get enough money to do anything at any one time so most of it gets wasted just keeping the infrastructure on life support.
"Parasitic wasps laying eggs in other insects is a better love story than Twilight." - :bitzero:
"Anyhow, it was the best sentient food movie since Killer Tomatoes Eat France." - :flipper:
"lee marvin in drag is no way to spread the gospel, son." - TFJ
"It's not like there was ever a time I didn't think Rudy Giuliani was a smug gibbering imbecile." - random axe
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Dr. Leonard HmofCoy

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Re: Geek lite question
« Reply #264 on: February 09, 2018, 09:31:41 PM »
It case it wasn't clear, all the orbital launch capacity the US has right now that's not SpaceX is owned by the DOD - both the Atlas 5 and Delta 4 rockets are entirely theirs. Orbital Sciences scarcely counts right now, they've blown it. And they go through defense procurement, which is a hilarious joke in terms of costs. If NASA wants one of those rockets they have to basically buy it from the DOD.
"Parasitic wasps laying eggs in other insects is a better love story than Twilight." - :bitzero:
"Anyhow, it was the best sentient food movie since Killer Tomatoes Eat France." - :flipper:
"lee marvin in drag is no way to spread the gospel, son." - TFJ
"It's not like there was ever a time I didn't think Rudy Giuliani was a smug gibbering imbecile." - random axe
"*drags taint* Oh cool, I didn't know you could do that." - mo.d

random axe

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Re: Geek lite question
« Reply #265 on: February 10, 2018, 10:27:24 AM »
:hmm:

It still seems implausible.  :lol:

But obviously it's happening.

Presumably, the same system could carry more payload (assuming it would fit in the capsule, or with a longer capsule) if it didn't have to carry the fuel used for landing.  Right?  Swap a pound of fuel for a pound of payload.  Actually, you'd get more than a pound of payload for a pound of fuel, since [ mumble amount ] of the landing fuel is basically lifted twice.

So the working theory here is that they're saving more money by recovering and reusing the rockets than they would make by lifting more payload or lifting that payload even cheaper.  I guess.

Dr. Leonard HmofCoy

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Re: Geek lite question
« Reply #266 on: February 11, 2018, 01:18:43 AM »
So the working theory here is that they're saving more money by recovering and reusing the rockets than they would make by lifting more payload or lifting that payload even cheaper.  I guess.

Yes that's the theory ... I actually don't believe it. They're running at a huge loss, despite their getting DOD contracts. People with infinite amounts of money can be infinitely risk-averse in the R&D stage, is what it looks like. I could be wrong.
"Parasitic wasps laying eggs in other insects is a better love story than Twilight." - :bitzero:
"Anyhow, it was the best sentient food movie since Killer Tomatoes Eat France." - :flipper:
"lee marvin in drag is no way to spread the gospel, son." - TFJ
"It's not like there was ever a time I didn't think Rudy Giuliani was a smug gibbering imbecile." - random axe
"*drags taint* Oh cool, I didn't know you could do that." - mo.d

random axe

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Re: Geek lite question
« Reply #267 on: February 11, 2018, 04:34:39 PM »
Musk does a lot of things for reasons that seem elusive.  I can't tell if he's likely to have master plans or if he's kind of a nut.  Seems 50/50.

I think he mostly wants to go to Mars and build a colony.  I don't blame him -- I wrote a story years ago that was basically about a billionaire who gradually becomes sufficiently obsessed with the concept to make it happen.  If private enterprise manages that first, and does it well, it'll make prior concepts of wealth look small.  It's the kind of thing that makes you redefine wealth from "money" to "hours" and "watts" and so on.

Things like the Rokon passive-landing rocket or the Shuttle Orbiter wouldn't work on Mars the same way, of course, because the atmosphere there is feeble.  If you want to land a spacecraft that can turn around and take off again, the Falcon system is in a plausible neighborhood.  It honestly makes more sense for Mars (or the moon) than for Earth.

Battery tech folds into any space venture easily enough, but if his Boring Company is related, then he's pursuing the wrong techniques so far, at least publicly.

Dr. Leonard HmofCoy

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Re: Geek lite question
« Reply #268 on: February 14, 2018, 06:10:10 PM »
Ah no, I figured that one out. He needs to develop technology to drill into the Martian regolith or hillsides or whatever so he can build habitats with cheap radiation shielding.
"Parasitic wasps laying eggs in other insects is a better love story than Twilight." - :bitzero:
"Anyhow, it was the best sentient food movie since Killer Tomatoes Eat France." - :flipper:
"lee marvin in drag is no way to spread the gospel, son." - TFJ
"It's not like there was ever a time I didn't think Rudy Giuliani was a smug gibbering imbecile." - random axe
"*drags taint* Oh cool, I didn't know you could do that." - mo.d

random axe

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Re: Geek lite question
« Reply #269 on: February 14, 2018, 06:23:24 PM »
That's just dumb, though.  You want robots that sinter dust.  So much easier to work with dust than rock, and there's so much free dust. 

Robot excavates a vertical hole, winds out skeleton of wire, adds mild current, dust sticks to the wire frame, sinter dust into walls.  Powder-coated radiation-shielded fabrication that's like Lego for robots.  Add tunnels to connect, put greenhouses above.

Maybe he's going to mount his giant cutting heads at the top of his rocket body, below the capsule or something?  Turn the salvaged hull into the hull of the boring machine?  Eh.  Inflexible, heavy, limited.  Seems silly.  Groups of robots seems a lot better, to me.

I like Mars, but I'm not sure about the gravity.  That might get problematic over the long term.  I know, lots of smarter people have debated this into the Martian ground, but it's the feeling that I get, and gravity is hard to fix.  By the time it isn't hard to fix, colonizing Mars will probably be beside the point.