Author Topic: tripropellant rockets  (Read 46916 times)

Offline jongoff

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Re: tripropellant rockets
« Reply #20 on: 02/06/2009 03:15 pm »
A hydrogen,kerosene, and oxygen rocket will likely produce the performance needed for a near SSTO for a lot less trouble.
Burning kerosene during the early phase of the flight reduces the size and mass of the tanks needed.
See MAKS http://www.buran.ru/htm/molniya6.htm

One of the interesting ways of doing a LOX/Kero/LH2 tripropellant rocket in a sensible way was suggested by Aerojet in one of their TAN papers.  Basically, you burn LOX/Kero in the TAN injectors, and LOX/LH2 in the core chamber.  The Kero is not just adding density impulse for the early part of the burn (and also decreasing gravity losses by being able to burn off quicker than a higher Isp fuel), but it is also allowing the main engine to have a much larger expansion ratio than you could get away with for a booster engine--giving much better Isp and engine T/W...

And yes, I wouldn't want to be with 100miles of someone dumb enough to be messing with Liquid Lithium and Florine in a rocket.

~Jon

Offline mlorrey

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Re: tripropellant rockets
« Reply #21 on: 02/07/2009 03:15 am »

And yes, I wouldn't want to be with 100miles of someone dumb enough to be messing with Liquid Lithium and Florine in a rocket.

~Jon

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Offline robertross

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Re: tripropellant rockets
« Reply #22 on: 02/11/2009 12:44 am »
And of course, if you want to go completely crazy, there's liquid ozone 15 and acetylene. But I'll let the co-author of that tongue-in-cheek proposal describe it himself:

http://groups.google.com/group/sci.space.tech/msg/3199d5be7e770f44

(The rest of the thread is worth reading, for tips on making the acetylene radioactive, etc...)
In a similar vein you have chlorine trifluoride, which was at least somewhat seriously considered as a propellant.

Thanks Jorge & hop...I had a good laugh from those. I really miss my chemistry 101. And from that last link, I loved this point (among others):

"It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water-with which it reacts explosively"

Offline jongoff

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Re: tripropellant rockets
« Reply #23 on: 02/11/2009 01:52 am »
And of course, if you want to go completely crazy, there's liquid ozone 15 and acetylene. But I'll let the co-author of that tongue-in-cheek proposal describe it himself:

http://groups.google.com/group/sci.space.tech/msg/3199d5be7e770f44

(The rest of the thread is worth reading, for tips on making the acetylene radioactive, etc...)
In a similar vein you have chlorine trifluoride, which was at least somewhat seriously considered as a propellant.

Thanks Jorge & hop...I had a good laugh from those. I really miss my chemistry 101. And from that last link, I loved this point (among others):

"It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water-with which it reacts explosively"

I still think that George Herbert's gag propellant HOOOCCH was the best.  Poly-Acetyl Ozone.

http://www.retro.com/hooocch/acezone.html

~Jon

Offline mlorrey

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Re: tripropellant rockets
« Reply #24 on: 02/11/2009 02:03 am »
And of course, if you want to go completely crazy, there's liquid ozone 15 and acetylene. But I'll let the co-author of that tongue-in-cheek proposal describe it himself:

http://groups.google.com/group/sci.space.tech/msg/3199d5be7e770f44

(The rest of the thread is worth reading, for tips on making the acetylene radioactive, etc...)
In a similar vein you have chlorine trifluoride, which was at least somewhat seriously considered as a propellant.

Thanks Jorge & hop...I had a good laugh from those. I really miss my chemistry 101. And from that last link, I loved this point (among others):

"It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water-with which it reacts explosively"

I still think that George Herbert's gag propellant HOOOCCH was the best.  Poly-Acetyl Ozone.

http://www.retro.com/hooocch/acezone.html

~Jon

How about lithium and peroxide?
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Offline kevin-rf

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Re: tripropellant rockets
« Reply #25 on: 02/11/2009 02:39 pm »

I still think that George Herbert's gag propellant HOOOCCH was the best.  Poly-Acetyl Ozone.

http://www.retro.com/hooocch/acezone.html

~Jon

The Job listing page is equally good enough ;)

http://www.retro.com/general/employment.shtml

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It's your med's!

Offline Patchouli

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Re: tripropellant rockets
« Reply #26 on: 02/11/2009 03:21 pm »

The MAKS concept looks ideal - but why would the Russian have been wasting time with Kliper then ACTS if MAKS was sitting there just waiting to be finished?

There are other considerations than ISP
Such as money plus relations with the Ukraine also MAKS only got a little farther then Orion is now.
The RD701 was tested and transition from tripropellant mode to bipropellant mode worked smoothly.
Though I think ACTS is now dead since the RSA and EU decided they should go their separate ways I didn't think it had much of a chance anyway.
 TsSKB and RSC favored the Kliper/parome a system over ACTS which was a Frankenstein creation that left holes in the cargo transportation end as far as Russia was concerned.
Russia doesn't like depending on other countries for services.

Lastly Kliper and ACTS were supposed to be able to go to the moon while MAKS is a pure LEO vehicle.

Still I bet they kick themselves for not finishing MAKS since MAKS-M and MAKS-D approach STS in some capabilities and would have given them something to compete with companies like Spacex and Arianespace with on equal grounds.

« Last Edit: 02/11/2009 03:37 pm by Patchouli »

Offline mlorrey

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Re: tripropellant rockets
« Reply #27 on: 02/12/2009 02:22 am »

Lastly Kliper and ACTS were supposed to be able to go to the moon while MAKS is a pure LEO vehicle.

Still I bet they kick themselves for not finishing MAKS since MAKS-M and MAKS-D approach STS in some capabilities and would have given them something to compete with companies like Spacex and Arianespace with on equal grounds.



ICBM people will always hate anything with wings.
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Offline Archibald

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Re: tripropellant rockets
« Reply #28 on: 02/13/2009 06:37 pm »
 a nice concept would be a Kistler K-1 with RD-701s (not NK-33 or NK-43)

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Offline tnphysics

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Re: tripropellant rockets
« Reply #29 on: 02/15/2009 01:22 am »
what about boranes?

Offline mmeijeri

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Re: tripropellant rockets
« Reply #30 on: 02/15/2009 02:13 am »
what about boranes?

Apparently very toxic. Silanes are apparently very promising, but also toxic.
Pro-tip: you don't have to be a jerk if someone doesn't agree with your theories

Offline gin455res

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Re: tripropellant rockets
« Reply #31 on: 03/09/2009 07:32 am »
Is it possible to get the effect of a tri-propellant with gelled fuels. For example if hydrogen was gelled with methane but the percentage of methane was stratified in the fuel tank so that there was lots of methane early in the burn and less as the burn continued?

And if we forget about fixating on maximum isp, is it possible to gell the hydrogen with alternate gelling agents that do not use up so much oxygen as methane. This would allow the fuel/oxidiser mixture ratio to vary less as the hydrogen/gellant mixture ratio changed.

In an article I found online, the hydrogen/methane (gelled) : oxygen ratio was 4:1 whereas the pure hydrogen : oxygen it was 6:1. Would there be any advantage in using alternative gelling agents so that this ratio would vary less as the mixture changed during the burn?

Perhaps, methanol, ammonia, nitromethane!!

Similarly, if there is a substance with a similar energy density/liter as methane but is far denser, then would it make any sense to gell this with methane in a similar stratified fashion? If the engine is running fuel rich then the effective energy densities would be less than that 'written on the can'  as there would be incomplete  combustion in the form of unreacted h2 and carbon monoxide. Some type of alcohol perhaps?

Offline mlorrey

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Re: tripropellant rockets
« Reply #32 on: 03/09/2009 08:18 pm »
Is it possible to get the effect of a tri-propellant with gelled fuels. For example if hydrogen was gelled with methane but the percentage of methane was stratified in the fuel tank so that there was lots of methane early in the burn and less as the burn continued?

And if we forget about fixating on maximum isp, is it possible to gell the hydrogen with alternate gelling agents that do not use up so much oxygen as methane. This would allow the fuel/oxidiser mixture ratio to vary less as the hydrogen/gellant mixture ratio changed.

In an article I found online, the hydrogen/methane (gelled) : oxygen ratio was 4:1 whereas the pure hydrogen : oxygen it was 6:1. Would there be any advantage in using alternative gelling agents so that this ratio would vary less as the mixture changed during the burn?

Perhaps, methanol, ammonia, nitromethane!!

Similarly, if there is a substance with a similar energy density/liter as methane but is far denser, then would it make any sense to gell this with methane in a similar stratified fashion? If the engine is running fuel rich then the effective energy densities would be less than that 'written on the can'  as there would be incomplete  combustion in the form of unreacted h2 and carbon monoxide. Some type of alcohol perhaps?

NASA's HEDM program researched gelling hydrogen with additives like aluminum, carbon, titanium and boron powders. All gave significant increases in IsP however questions remain about coking issues in any turbopumps used by engines burning these gells.
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Offline mlorrey

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Re: tripropellant rockets
« Reply #33 on: 03/09/2009 11:34 pm »
http://www.wickmanspacecraft.com/loxmono.html

Check 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?
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Offline khallow

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Re: tripropellant rockets
« Reply #34 on: 03/10/2009 05:13 am »
http://www.wickmanspacecraft.com/loxmono.html

Check 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?

How about outgassing? Seems likely that anything you vent would instantaneous burn at room temperature.

What few rumors I heard on this seems to indicate that this is a very unstable mix. For example, suppose I leave a little petroleum grease smear on the inside of a LOX tank. The grease will burn in the presence of LOX, but the energy released is merely that of the burning grease. In this LOX/kerosene mix, grease contamination might instantly detonate the whole mix (in the usual explosive sense with supersonic wavefront and everything). So this system, at least, seems much more sensitive to contamination than what we have today.

It might spontaneously react too. A very energetic cosmic ray (I love blaming these guys) or a static discharge somewhere in your plumbing might set off your propellant. You'd have to put in safeguards to keep a combustion wavefront from racing into your tank from elsewhere.
Karl Hallowell

Offline GI-Thruster

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Re: tripropellant rockets
« Reply #35 on: 03/12/2009 06:20 pm »
Anyone interested in using more energetic propellants will want to track the progress at Harvard and look for the SPESIF paper by Dr. John W. Cole (of MSC fame) and Dr. Isaac F. Silvera of Harvard entitled "Metallic Hydrogen Propelled Launch Vehicles for Lunar Missions" where you will find amongst other things, some raw numbers for such vehicles.  Given metallic hydrogen as a fuel, one could for example fly single stage to the moon with a 65 m high, 452 MT GLOW and land 45 MT on the lunar surface.

That's not your mother's hydrogen thruster. . .

Offline modavis

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Re: tripropellant rockets
« Reply #36 on: 03/12/2009 07:54 pm »
It isn't very different from a pebble bed nuclear reactor.

It's different in at least one very significant way.

The greatest virtue of the PBR that, unlike the tubes and rods and channels of earlier reactors, no elaborate structure is needed to position the fissionables. Given the flux of heat-transfer fluid needed, even in the worst case the maximum energy available to move the "pebbles" around is safely less than it would take to damage them, and there's no arrangement of pebbles that would choke the flow.

The flux of reaction mass through a NTR is much higher. The momentum per unit engine mass (aka "how fast does it tear itself apart if something goes wrong") is orders of magnitude higher. So it does need a structure that holds the fissionables in a fixed arrangement and maintains clear channels. And if that begins to fail, there is more than enough momentum around to turn a small flaw into a big one really fast.

I happen to think NTRs are promising, and we now know how to sinter fuel elements tougher than those in NERVA or Timberwind. But the comparison to a PBR is still disingenuous: the design principles are deeply different.   

 

Offline GI-Thruster

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Re: tripropellant rockets
« Reply #37 on: 03/13/2009 01:55 pm »
Just continuing on with John Cole's latest on metallic hydrogen. . .this is a state change reaction, going from atomic solid molecular releases 216 MJ/kg.  Temp for this is >5600K or 9600F with an Isp in the 1700's so John proposes cooling with liquid H2 or water.  There are several different case studies, the most efficient of which seems to be the two stage to the Moon, water cooled.  Nice tables with the winner seeming to be an Isp of about 900-1100 or the edge of what present day materials can handle.  Tables with Lunar mission requirements, dv per maneuver, mix ratios, mass fractions, comparisons with Saturn V, Titan IV, Delta IV-H and Atlas V, vehicle sizing calculations and charts including Shuttle, Saturn V and the stick for comparison.

Great paper to look for once AIP publishes.

Offline khallow

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Re: tripropellant rockets
« Reply #38 on: 03/13/2009 06:20 pm »
Thing is, as far as I know, you have to store metallic hydrogen under tremendous pressure, a million atmospheres or more. You probaby  can generate useful thrust from just about any gas at that pressure.
Karl Hallowell

Offline GI-Thruster

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Re: tripropellant rockets
« Reply #39 on: 03/13/2009 08:56 pm »
Karl, the first half of the paper concerns the experiments to create metallic hydrogen.  I doubt it's fair even to say they've created enough to know the answer to that but in general, it is being portrayed as "metastable" so it is stable with specific temperature.  Meaning, they think if they keep it cold, as in immersed in liquid H2, then it will stay in its metallic state.  Of course, if they're wrong, there's a big boom.

Aren't you the one who said earlier, supersonic detonation and all that. . .very bad hair day for everyone within miles. . .

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