http://www.wickmanspacecraft.com/loxmono.htmlCheck this out, these guys are mixing LOX with kerosene at cryogenic temps to create a 'monopropellant'. Dont know how stable this mixture is, but it could save some tankage mass if you only need one tank, and making it pressure fed, eliminate turbopumping, you'd have the liquid equivalent of a solid rocket motor. Comments?
Quote from: mlorrey on 03/09/2009 11:34 pmhttp://www.wickmanspacecraft.com/loxmono.htmlCheck this out, these guys are mixing LOX with kerosene at cryogenic temps to create a 'monopropellant'. Dont know how stable this mixture is, but it could save some tankage mass if you only need one tank, and making it pressure fed, eliminate turbopumping, you'd have the liquid equivalent of a solid rocket motor. Comments?Wouldn't mixing fuel and oxidizer in this manner turn the liquid engine into a bomb waiting to explode, even worse than a solid motor? This would greatly increase your LOC numbers. Also you might have problems if the density of LOX and cryogenic RP vary as you may have some settling when accelerating at multiple Gs. If the fuel or the oxidizer floats to the top then you are in serious trouble.
Quote from: space_dreamer on 02/05/2009 02:28 pmI have been reading about of Wikipedia. ( http://en.wikipedia.org/wiki/Tripropellant_rocket )It says - A mixture of lithium, hydrogen, and fluorine produced a specific impulse of 546 seconds; the highest ever of any chemical rocket motor.An Isp of 546 is high enough to design a signal stage to orbit vehicle SSTO. Does anybody know, why an engine for this combination of fuel not being developed? The propellants and exhaust are extremely toxic.
I have been reading about of Wikipedia. ( http://en.wikipedia.org/wiki/Tripropellant_rocket )It says - A mixture of lithium, hydrogen, and fluorine produced a specific impulse of 546 seconds; the highest ever of any chemical rocket motor.An Isp of 546 is high enough to design a signal stage to orbit vehicle SSTO. Does anybody know, why an engine for this combination of fuel not being developed?
Quote from: Jim on 02/05/2009 02:38 pmQuote from: space_dreamer on 02/05/2009 02:28 pmI have been reading about of Wikipedia. ( http://en.wikipedia.org/wiki/Tripropellant_rocket )It says - A mixture of lithium, hydrogen, and fluorine produced a specific impulse of 546 seconds; the highest ever of any chemical rocket motor.An Isp of 546 is high enough to design a signal stage to orbit vehicle SSTO. Does anybody know, why an engine for this combination of fuel not being developed? The propellants and exhaust are extremely toxic.monomethal hydrozine and nitrogen tettroxide are toxic too and they use them
Quote from: cheesybagel on 02/06/2009 01:53 amIf you are going for hazardous rockets, my personal favorite is the pebble bed nuclear thermal rocket with LH2 as the ejection mass ala Project Timberwind. T/W ratio of 30 and 890 Isp at sea level. LN or CO2 as the ejection mass would increase thrust at cost of Isp. It isn't very different from a pebble bed nuclear reactor. Many countries have the technology required, including China.That engine may be too dangerous for an LV but it would rock for a lunar shuttle no more launching a new EDS for every lunar mission just refuel the nuclear ferry.Also with a T/W that high if it can throttle deeply and quickly it would make a good lunar lander engine too.
If you are going for hazardous rockets, my personal favorite is the pebble bed nuclear thermal rocket with LH2 as the ejection mass ala Project Timberwind. T/W ratio of 30 and 890 Isp at sea level. LN or CO2 as the ejection mass would increase thrust at cost of Isp. It isn't very different from a pebble bed nuclear reactor. Many countries have the technology required, including China.
I think I read on here, that the cubed square law means that as rocket engines get larger they need less cooling.Could tri-propellants take advantage of this once a certain size engine is reached by using only one fuel for both cooling and in the pump gas-generator?For example, if the engine ran on LOX, kerosene and alcohol, could it reach a size where only the alcohol is needed for cooling (here the tri-propellant is purely used to improve re-usability by eliminating coking, not for density advantages)?
RD-701 used hydrogen and no RP-1 for cooling iirc, though someone might correct me.
Quote from: Patchouli on 02/06/2009 02:12 amQuote from: cheesybagel on 02/06/2009 01:53 amIf you are going for hazardous rockets, my personal favorite is the pebble bed nuclear thermal rocket with LH2 as the ejection mass ala Project Timberwind. T/W ratio of 30 and 890 Isp at sea level. LN or CO2 as the ejection mass would increase thrust at cost of Isp. It isn't very different from a pebble bed nuclear reactor. Many countries have the technology required, including China.That engine may be too dangerous for an LV but it would rock for a lunar shuttle no more launching a new EDS for every lunar mission just refuel the nuclear ferry.Also with a T/W that high if it can throttle deeply and quickly it would make a good lunar lander engine too.NTR for a lunar shuttle is not really a good idea either because the logistics are a PITA. In vacuum, neutron radiation goes down as an inverse square law instead of exponentially with distance, and mostly unshielded multi-gigawatt nuclear reactors are REALLY neutron-bright during engine burns. Everyone in a lunar bases that it flies over or lands next to has to go into a radiation shelter. On top of it, you only get an ISP advantage if all your reaction mass is hydrogen... which is the only thing which is in really short supply on the surface of the moon. If you have an oxygen source which is trivial for the moon, then hydrolox ISRU uses hydrogen from earth much more efficiently.
EDIT: holy necroposting