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It seems to me that being satan's sriracha is way less likely to disqualify something from being a rocket fuel than not being able to force it through a turbopump quickly enough.
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Apr 10, 2016 23:31
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xthetenth posted:It seems to me that being satan's sriracha is way less likely to disqualify something from being a rocket fuel than not being able to force it through a turbopump quickly enough. How about a cryogenic "solid" booster? Cool the drat thing with LN2 until takeoff and hope it doesn't melt and decompose completely before it burns. Of course it might well detonate in place, and I doubt it would be friendly to whatever you make the booster body out of, but ...
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Apr 11, 2016 02:04
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xthetenth posted:It seems to me that being satan's sriracha is way less likely to disqualify something from being a rocket fuel than not being able to force it through a turbopump quickly enough. This or unbelievable toxicity. Being amazingly hypergolic isn't so much a bad thing - the main criteria for rocket fuel is "Is it a good fuel (ie, compressible)" and "if I launch this, and it crashes, will it poison vast areas of land?", which the reason why we don't use dimethyl mercury as a rocket fuel (iirc, it was actually a very good rocket fuel) or nuclear rockets.
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Apr 11, 2016 02:48
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A White Guy posted:This or unbelievable toxicity. Being amazingly hypergolic isn't so much a bad thing - the main criteria for rocket fuel is "Is it a good fuel (ie, compressible)" and "if I launch this, and it crashes, will it poison vast areas of land?", which the reason why we don't use dimethyl mercury as a rocket fuel (iirc, it was actually a very good rocket fuel) or nuclear rockets. oh they went further than that, time to quote John Clark again Ignition! posted:Phil wanted density. Well, dimethyl mercury was dense, all right — d = 3.07 —but it would be burned with RFNA, and at a reasonable mixture ratio the total propellant density would be about 2.1 or 2.2. (The density of the acid-UDMH system is about 1.2.) That didn't seem too impressive, and I decided to apply the reducto ad absurdum method. Why not use the densest known substance which is liquid at room temperature — mercury itself? Just squirt it into the chamber of a motor burning, say, acid-UDMH. It would evaporate into a monatomic gas (with a low Cp, which would help performance), and would go out the nozzle with the combustion products. That technique should give Phil all the density he wanted!
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Apr 11, 2016 03:22
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A White Guy posted:This or unbelievable toxicity. 
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Apr 11, 2016 12:28
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Collateral Damage posted:Doesn't stop the russians from using UDMH and N2O4. when you start using the russians as a good example of great ideas... Is there any way to subscribe to individual posters so i can see how this goes?  just noticed av/post c-c-c-c-c-ombo! 
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Apr 11, 2016 12:31
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SneakyFrog posted:when you start using the russians as a good example of great ideas...  In fact I'm pretty sure that the Intelsat 708 crash that supposedly wiped out a nearby village is an example of what a terrible idea it is.
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Apr 11, 2016 12:47
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Collateral Damage posted:Never said it was a good idea. me is slow this morning. caffination in progress please standby.
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Apr 11, 2016 12:59
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Does anyone have a phase diagram for KrF2 handy? -78 Celsius isn't bad at all as far as cryogenics are concerned (LH2 is about 30K, and it's heavily used as rocket fuel). As far as nuclear rockets go, I was always a fan of the nuclear light bulb.   Uranium gas at 55000 K  (It would have amazing performance though.)
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Apr 11, 2016 13:12
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Something tells me it would also be very efficient at irradiating the living poo poo out of everything that went anything near the general direction of the exhaust 
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Apr 11, 2016 13:19
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Ignimbrite posted:Something tells me it would also be very efficient at irradiating the living poo poo out of everything that went anything near the general direction of the exhaust That's a problem for Public Relations to solve, we're in Engineering around here 
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Apr 11, 2016 14:09
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Ignimbrite posted:Something tells me it would also be very efficient at irradiating the living poo poo out of everything that went anything near the general direction of the exhaust The closed cycle design (first picture) doesn't have any physical contact between the fissiles and the exhaust, so unless there's some sort of mechanical failure there will be no radiation release. If you want to irradiate people, the NSWR is a much better option (it's best described as a continuously detonating Orion drive). Although, according to the atomic rockets page, using 90% enriched uranium as fuel will get you a specific impulse of about half a million seconds. (People who aren't Robert Zubrin are skeptical about whether this would actually work). LostCosmonaut has a new favorite as of 14:26 on Apr 11, 2016 |
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Apr 11, 2016 14:21
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Ignimbrite posted:Something tells me it would also be very efficient at irradiating the living poo poo out of everything that went anything near the general direction of the exhaust Radiation is the least of your concerns, that much uranium gas would poison to death anything that so much as looked at the exhaust plume, also the rocket runs hot enough it would vaporize tungsten. It's the unholy trifecta of rocket designs: super efficient, super deadly, and super bad in the long run.
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Apr 11, 2016 14:29
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Ignimbrite posted:Something tells me it would also be very efficient at irradiating the living poo poo out of everything that went anything near the general direction of the exhaust Could be worse, could be relying on circular motion to keep the uranium on the edges rather than the part that gets exhausted. On the downside, fewer density impulse boosting happy accidents. Just remember that the hot/crazy scale is for rocket propulsion and any other use is a misapplication.
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Apr 11, 2016 14:44
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Computer viking posted:How about a cryogenic "solid" booster? Cool the drat thing with LN2 until takeoff and hope it doesn't melt and decompose completely before it burns. Of course it might well detonate in place, and I doubt it would be friendly to whatever you make the booster body out of, but ... So it succeeds at being a solid booster. Just happens to be omnidirectional.
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Apr 11, 2016 16:02
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LostCosmonaut posted:If you want to irradiate people, the NSWR is a much better option (it's best described as a continuously detonating Orion drive). Although, according to the atomic rockets page, using 90% enriched uranium as fuel will get you a specific impulse of about half a million seconds. quote:Details are scarce since the project is still classified after all these years. Tungsten has an atomic number (Z) of 74. When the tungsten plate is vaporized, the resulting plasma jet has a relatively low velocity and diverges at a wide angle (22.5 degrees). Now, if you replace the tungsten with a material with a low Z, the plasma jet will instead have a high velocity at a narrow angle ("high velocity" meaning "a recognizable fraction of the speed of light"). The jet angle also grows narrower as the thickness of the plate is reduced. This is undesirable for a propulsion system component (because it will destroy the pusher plate), but just perfect for a weapon (because it will destroy the enemy ship). Bhodi has a new favorite as of 16:31 on Apr 11, 2016 |
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Apr 11, 2016 16:26
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Collateral Damage posted:Doesn't stop the russians from using UDMH and N2O4. Or us. We used it on Gemini and a bunch of ICBMs.
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Apr 11, 2016 17:07
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Kwyndig posted:also the rocket runs hot enough it would vaporize tungsten Great, more reaction mass!
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Apr 11, 2016 17:25
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Collateral Damage posted:Doesn't stop the russians from using UDMH and N2O4. Us Americans are way more cautious, we use MONOmethyl-hydrazine with our N2O4. But for real everyone uses hypergolics once you've detached from the stack.
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Apr 11, 2016 17:48
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Zopotantor posted:Great, more reaction mass! If that's your reaction 'will destroy anything reasonable we can make the rocket out of' then you're secretly a rocket engineer, aren't you?
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Apr 11, 2016 20:58
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Bhodi posted:the coolest thing that came out nuclear shaped-charge research was the "Casaba-Howitzer" program which is a still-classified nuclear directed energy weapon It's one thing I never got about the Star Trek/Star Wars universes, if you have FTL travel why do you need some massive fleet of super weapons when all it takes is a Volvo going .99c smacking into a planet to completely ruin the biosphere forever? Not to mention warp drive, holy poo poo a pinhead traveling at those velocities would annihilate planets. Got enemies? Set a drone to warp 9 into their home planet. No more enemies.
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Apr 11, 2016 21:09
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Kwyndig posted:If that's your reaction 'will destroy anything reasonable we can make the rocket out of' then you're secretly a rocket engineer, aren't you? The platonic ideal of propulsion is sending the entire propulsion system rearwards at high velocity.
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Apr 11, 2016 21:10
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I think in Star Trek they get around that by saying warp drives don't cause relativistic effects, so something moving at .99c doesn't have near infinite potential kinetic energy trapped into its momentum if it's under warp. That shouldn't stop them from using gravity to hurl giant rocks at poo poo though.
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Apr 11, 2016 21:12
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Kwyndig posted:I think in Star Trek they get around that by saying warp drives don't cause relativistic effects, so something moving at .99c doesn't have near infinite potential kinetic energy trapped into its momentum if it's under warp. Hurling giant rocks at poo poo is banned in the Space Geneva Convention.
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Apr 11, 2016 21:16
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Hurling giant rocks is the subject of a great bit of 40k fluff detailing the fuel and supplies it would take to get a rock and protect it until impact a long time later, and concluding with just shooting the planet being much cheaper.
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Apr 11, 2016 21:19
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Kwyndig posted:I think in Star Trek they get around that by saying warp drives don't cause relativistic effects, so something moving at .99c doesn't have near infinite potential kinetic energy trapped into its momentum if it's under warp.
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Apr 11, 2016 21:21
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xthetenth posted:Hurling giant rocks is the subject of a great bit of 40k fluff detailing the fuel and supplies it would take to get a rock and protect it until impact a long time later, and concluding with just shooting the planet being much cheaper. Well yeah, that's 40k, any competently defended world is already going to have giant cannons pointed at the sky to blow up incoming rocks because they might have Orks in them.
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Apr 11, 2016 21:21
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Also, if you can ignore relativistic effects with your ship, you just have a little ship scoot over the the rock and nudge it over to the side a bit.
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Apr 11, 2016 21:22
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one of the movies involves a non-governmental actor setting off supernovas and it is treated just like a dude having access to nuclear weapons; real bad but hardly an unknown variable flinging rocks just can't rate
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Apr 11, 2016 21:30
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xthetenth posted:Hurling giant rocks is the subject of a great bit of 40k fluff detailing the fuel and supplies it would take to get a rock and protect it until impact a long time later, and concluding with just shooting the planet being much cheaper. you don't really have to defend the rock though, just coat it in something IR absorbent with a heat sink on the back and let it fly. if they shoot it it just becomes a million tiny rocks which is probably worse.
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Apr 11, 2016 22:04
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Minarchist posted:It's one thing I never got about the Star Trek/Star Wars universes, if you have FTL travel why do you need some massive fleet of super weapons when all it takes is a Volvo going .99c smacking into a planet to completely ruin the biosphere forever? Not to mention warp drive, holy poo poo a pinhead traveling at those velocities would annihilate planets. Got enemies? Set a drone to warp 9 into their home planet. No more enemies. In Star Wars the handwaving is that you can't travel through hyperspace too close to a gravity well, the Empire even has special star destroyers that use captive black holes or some poo poo to project a "mass shadow" that will pull a hyperspacing ship into realspace if it passes through it. So trying to use a hyperspace Volvo to destroy a planet would just result in the Volvo dropping out of hyperspace back to a much slower speed once it got close enough to the planet, and depending on the author the Volvo would probably just blow up too. No idea bout the Trekfluff.
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Apr 11, 2016 23:11
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Phanatic posted:In Star Wars the handwaving is that you can't travel through hyperspace too close to a gravity well
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Apr 11, 2016 23:20
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Collateral Damage posted:Which they handily break in The Force Awakens when the Millenium Falcon drops out of hyperspace at treetop level at the new death Ah you see, the falcon is
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Apr 11, 2016 23:22
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Tunicate posted:Ah you see, the falcon is Something something Kessel run in 12 parsecs.
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Apr 11, 2016 23:28
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well you see the planet sized superweapon somehow no longer has a gravity well, therefore
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Apr 11, 2016 23:39
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Phanatic posted:In Star Wars the handwaving is that you can't travel through hyperspace too close to a gravity well, the Empire even has special star destroyers that use captive black holes or some poo poo to project a "mass shadow" that will pull a hyperspacing ship into realspace if it passes through it. So trying to use a hyperspace Volvo to destroy a planet would just result in the Volvo dropping out of hyperspace back to a much slower speed once it got close enough to the planet Because the computer pulls it out.
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Apr 11, 2016 23:40
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Avenging_Mikon posted:Because the computer pulls it out. The pulling out method really isn't all that safe .
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Apr 11, 2016 23:53
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xthetenth posted:The platonic ideal of propulsion is sending the entire propulsion system rearwards at high velocity. The problem there is that the propulsion system would rapidly transform into a cloud of poisonous radioactive plasma that would also consume the craft. Now, if you could invent an propulsion system that could safely disintegrate into reaction mass and hurl itself away that would be fantastic... that design was not it though.
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Apr 12, 2016 00:56
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Thinking in terms of actual physics, our own interpretation of warp drive would also be expanding space and then shrinking, so you actually can't just throw a theoretical piece of German engineering into a planet at .99c. However, the amount of energy you'd need to get your Volvo functioning as an Alcubierre drive is more than enough to just outright vaporize earth sized objects soo
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Apr 12, 2016 01:24
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So what you're saying is we need to use Mazdas and not Volvo's?
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Apr 12, 2016 02:27
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