Subject: Space-tech Digest #140 Contents: Big Dumb Booster discussion (18 msgs) ------------------------------------------------------------ Date: Thu, 3 Dec 92 12:40:26 EST From: Paul Carr Subject: Big Dumb Question To: space-tech@cs.cmu.edu It's probably obvious to everyone but me: Why does a symmetrical Launch vehicle need roll control on ascent? Any thrust direction can be achieved with only two degrees of freedom. Is it that the thing might spin up so much that gyroscopic stiffness threatens the yaw/pitch controls? The gyros saturate? Or coriolis forces are a problem? Just curious. It seems like something you could analyze away. ------------------------------ From: henry@zoo.toronto.edu Date: Thu, 3 Dec 92 13:03:33 EST To: space-tech@cs.cmu.edu Subject: Re: Readable Book About Rocket Fuels >I recommend the book: >_Ignition! An informal history of liquid rocket propellants._ >by John Clark (1972, Rutgers Univ Press)... >A good read. But try finding a copy (other than in a good library). It's unobtainable. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ From: henry@zoo.toronto.edu Date: Thu, 3 Dec 92 14:09:18 EST Subject: Big Dumb Question To: space-tech@cs.cmu.edu >Why does a symmetrical Launch vehicle need roll control on ascent? There are sometimes minor asymmetries in things like communications antennas or guidance gyro packages that can matter even if the vehicle has no gross asymmetry. If the spin rate gets *too* high, you'll start to have trouble with things like fluid flow, possibly even structural problems. The main reason for concern, though, is that yaw/pitch actuators, e.g. engine gimbals, have a finite maximum movement rate. If the vehicle is rolling, those actuators have to swap roles in sync with the roll rate, and if the roll rate gets high enough, they can't keep up. Some of the simpler missiles, e.g. Sidewinder, don't bother to stop roll entirely but do make arrangements to limit it. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Thu, 3 Dec 92 14:17:50 -0500 From: dietz@cs.rochester.edu To: space-tech@cs.cmu.edu Subject: Half-pressure-fed engines? I was wondering if one could go with a kind of half-pressure fed engine. That is: gas bled from the combustion chamber (or from a cooler preburner of some kind) is used to pressurize the propellant tanks to nearly the chamber pressure. Of course, this won't make fuel flow into the combustion chamber, so a pump is needed. However, this pump need only overcome the pressure drop in the lines and injector, and so could be much less powerful than in a purely pump-fed rocket, in which the pumps must nearly fully pressurize the propellant. In Bruce's P2-E, some .1 m^3 of liquid helium is needed to pressurize each m^3 of propellant tank. A turbopump brings the helium up to tank pressure (7.5 MPa) from low pressure. If a propellant pump need only pump the fuel through a pressure drop of ~.75 MPa, it would need be no more powerful than the helium pump Bruce is already assuming (power going as volume rate x change in pressure). Moreover, the fuel pump would be operating at a rather high net head pressure, and on a storable propellant, and so should be easier to design than a pump operating with a low intake pressure with a low-boiling cryogen like helium. A particularly simple kind of pump is the ejector pump, where a jet of some fluid entrains and pressurizes another fluid. Perhaps such a pump would be useful in this situation. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ To: Bruce Dunn Cc: space-tech@cs.cmu.edu, gwh@soda.berkeley.edu Subject: Re: Nitric acid Date: Thu, 03 Dec 92 12:29:11 -0800 From: gwh@lurnix.COM Thanks to Bruce Dunn and Paul Dietz for yet more information and suggestions. Aluminum is an acceptable fuel (sans Magnesium) if when mixed with the Improved RFNA (with some hydroflouric acid) it oxidizes on the surface, not burns. That undoes most of the fuel reaction safety problems. I suspect I'll lose a few seconds of Isp, but that's tolerable. Project for this week/weekend: firming up a test schedule for the fuel and oxidizer mix. Right now I have (comments invited): 0 Safety tests of freezing IRFNA or just INA 1 Safety test burn of oxidizer and fuel (unconfined) (4 runs) 2 Test burn with cracks in fuel and oxidizer (4 runs) 3 Test series, slowly increasing confinement to 600 PSI chamber pressure burns (6-12 runs) 4 Specific Impulse test series at 600 PSI (10 runs) 5 5a: third stage motor w/heavy casing 5b: flight wt. casing 6 6a: first/second stage "" 6b: first/second stage "" 7 Flight test of guidance system and first stage motor unit 8 Orbital Flight of small vehicle shown before I've recieved offers for donations to help with this... general comment on this. Any donations will be used only for costs associated with these tests or launches, or will be returned to the donators. -george william herbert Retro Aerospace gwh@lurnix.com gwh@soda.berkeley.edu gwh@retro.com [nic approval pending] netcom!retro!gwh ------------------------------ Date: Fri, 4 Dec 92 16:55:30 PST From: gwh@lurnix.COM (George W Herbert) To: space-tech@cs.cmu.edu Subject: Hybrid Reports I just recieved about ten pounds of copies of various technical reports on Hybrid propulsion: most have to do with the NASA idea of replacing the shuttle Boosters with hybrids, but there is some othe information in there too. I'll be providing summaries of the reports as I wade through them. They were provided by Bryan Palaszewski, who's the head of the Metallized Propellant Program at NASA Lewis. [Thanks, Bryan!] -george william herbert Retro Aerospace ------------------------------ From: ssi!lfa@uunet.UU.NET (Louis F. Adornato) Subject: IRFNA and Hydrazine To: uunet!cs.cmu.edu!space-tech@uunet.UU.NET Date: Mon, 7 Dec 92 8:46:15 CST X-Mailer: ELM [version 2.3 PL11] Doesn't the shuttle use IRFNA and Hydrazine (specfically, unsymetyric dimethyl hydrazine) as RCS fuel? As I recall, tanking the RCS requires that everyone within 3 miles or so be in a full CBW rig. Or is that because of the hydrazine? Lou Adornato | "Sure, the cow may have jumped over the Supercomputer Systems, Inc | moon, but she burned up on reentry" Eau Claire, WI | The secretary (and the rest of the company) uunet!ssi!lfa or lfa@ssi.com | have disavowed any knowledge of my actions. ------------------------------ From: henry@zoo.toronto.edu Date: Mon, 7 Dec 92 15:53:00 EST Subject: Re: IRFNA and Hydrazine To: space-tech@cs.cmu.edu >Doesn't the shuttle use IRFNA and Hydrazine (specfically, unsymetyric >dimethyl hydrazine) as RCS fuel? No, nitrogen tetroxide and monomethyl hydrazine. >As I recall, tanking the RCS requires >that everyone within 3 miles or so be in a full CBW rig. Or is that >because of the hydrazine? Both NT and MMH are truly vile substances that need extensive precautions. NT would make a good war gas by WWI standards. The hydrazines in general are poisonous, volatile, flammable, corrosive, carcinogenic, and prone to spontaneous decomposition or even explosion. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Tue, 8 Dec 92 19:25 PST From: trost@cse.ogi.edu (Bill Trost) To: George William Herbert Subject: Big Dumb Booster evolves some more... cc: space-tech@CS.CMU.EDU A couple "issues": How much nitric acid is going to end up in the exhaust? Is it something you should worry about? What are you going to say to all the folks who are going to worry about it anyway (and no, I don't think "go fly a kite" will cover it... :-) )? How does the range safety stuff need to change now that the oxidizer is frozen? I vaguely remember some discussion of range safety for one of these chea...er, inexpensive rockets, but the details are *real* hazy. ------------------------------ To: uunet!cse.ogi.edu!trost@uunet.UU.NET (Bill Trost) Cc: George William Herbert , space-tech@CS.CMU.EDU, gwh@lurnix.COM Subject: Re: Big Dumb Booster evolves some more... Date: Wed, 09 Dec 92 11:48:43 -0800 From: gwh@lurnix.COM >How much nitric acid is going to end up in the exhaust? Good question. I would suspect "not much", but that will definitely be something testing will have to verify. The Good news is that while nitric acid isn't all that friendly a thing to dump into the atmosphere, it's not going to cause ozone hole problems, and will likely come out of the atmosphere before it reaches land in Europe or anywhere, so it won't be a significant acid rain problem... >How does the range safety stuff need to change now that the oxidizer >is frozen? Treat it more or less like a solid; to terminate thrust, poke a hole in the front or side of the casing (probably with an explosive charge). I'm looking at a foot of primacord to blow the top off the engine units on the little vehicle. -george ------------------------------ Date: Wed, 9 Dec 92 15:27:00 -0500 From: dietz@cs.rochester.edu To: gwh@lurnix.COM Subject: Re: Big Dumb Booster evolves some more... Cc: space-tech@cs.cmu.edu The question arose: "How much nitric acid will end up in the exhaust?" The answer should be almost none, for two reasons: (1) Engines are typically run fuel-rich, and (2) Nitric acid itself decomposes to oxygen, water and nitric oxide at fairly modest temperature. BTW, can anyone tell me the fuels used in China's Long March series of boosters? Also, what fuels are used in the liquid strap-ons for the LM-2E? Paul ------------------------------ From: henry@zoo.toronto.edu Date: Wed, 9 Dec 92 17:05:16 EST Subject: Re: Big Dumb Booster evolves some more... To: space-tech@cs.cmu.edu >BTW, can anyone tell me the fuels used in China's >Long March series of boosters? Also, what fuels are >used in the liquid strap-ons for the LM-2E? I believe all their liquid stuff is N2O4/hydrazine at present. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Wed, 9 Dec 92 18:47:59 -0500 From: dietz@cs.rochester.edu To: henry@zoo.toronto.edu Subject: Re: Big Dumb Booster evolves some more... Cc: space-tech@cs.cmu.edu >> ... what fuels are >> used in the liquid strap-ons for the LM-2E? henry said: > I believe all their liquid stuff is N2O4/hydrazine at present. The exhaust from the strap-ons is very bright in the AW&ST cover from October. That suggests to me that it has some soot in it, which would suggest a hydrocarbon fuel. Paul ------------------------------ To: uunet!cs.rochester.edu!dietz@uunet.UU.NET Cc: gwh@lurnix.COM, space-tech@cs.cmu.edu Subject: Re: Big Dumb Booster evolves some more... Date: Wed, 09 Dec 92 14:35:35 -0800 From: gwh@lurnix.COM Paul's comment about fuel rich engines is good, but until we actually run some tests I'm not sure _what_ exact ratio is good with these propellants. *shrug* As for the Long March, all the LM vehicles use Hydrazine/Tetroxide liquid fuel in both core stages (all except third stage on some variants) and all the boosters. The LM-2E is quite comperable to the Arianne 44L in size, configuration, fuel, etc. if not quite the same payload to GTO. [One of the people I was working with this summer is the chief engineer of the LM-3 program 8-) he was a lot of fun to talk to.] -george ------------------------------ To: space-tech@cs.cmu.edu Subject: Re: Big Dumb Booster evolves some more... Date: Wed, 09 Dec 92 19:21:05 -0500 From: Randy Appleton I'm curious about all these people who talk about doing rocket experiments in one's own backyard (or similar places). How does one get 'primacord' or nitric oxide. Are these things anyone can get, or do I need a permit? -Just Curious -Randy ------------------------------ To: space-tech@cs.cmu.edu Subject: Re: Big Dumb Booster evolves some more... Date: Thu, 10 Dec 92 08:21:05 EST From: Chris Jones From: henry@zoo.toronto.edu Date: Wed, 09 Dec 92 17:05:16 EST >BTW, can anyone tell me the fuels used in China's >Long March series of boosters? Also, what fuels are >used in the liquid strap-ons for the LM-2E? I believe all their liquid stuff is N2O4/hydrazine at present. I recall reading that when the Soviet Union launched their first (and only) LH2/LOX design (Energiya core), that "even the Chinese" had already launched a LH2/LOX engine. According to the 16 March 1992 AW&ST, the CZ-3 and CZ-4 launchers include such stage(s) (they are really sketchily described as three stage launchers, being said to be capable of launching "Heavy payloads" to escape velocity). (It looks like all their other engines (including strapons?) are UDMH/N2O4 powered.) Combining this table with information from an article in the 5 October 1992 AW&ST, the Chinese boosters look something like this: Launcher Stages Thrust Payload (lbs.) LEO Escape CZ-2C 2 625,930 CZ-2D 2 CZ-2E 2 1,322,400 20,240 CZ-3A 3 661,200 5510 7,414* CZ-3B 10,560* CZ-3 3 625,930 -- Heavy CZ-4 3 661,200 -- " " (* payload to GTO) I believe variant of the CZ-3 or CZ-4 will have the LH2/LOX combination. The CZ-3B is said to be set for first launch in 1995. The CZ-3 is described as older than the CZ-2E, which had its first successful launch this past August. ------------------------------ To: Randy Appleton Cc: space-tech@cs.cmu.edu, gwh@lurnix.COM Subject: Re: Big Dumb Booster evolves some more... Date: Thu, 10 Dec 92 11:54:35 -0800 From: gwh@lurnix.COM Nitric Oxide is a hazardous substance. While you might be able to find a company stupid enough to sell and ship you some, the EPA could declare your place of residence an improperly managed hazardous material storage area immediately upon delivery. I suggest you avoid it like the plague. [Oh, the Shuttle had to be decontaminated after landing this time by air-tank-and-full-suit decontam crews after one of the tetroxide tanks or lines leaked.] Primacord is an explosive; you have to have a permit from the Federal Bureau of Alcohol, Tobacco and Firearms (ATF) and potentially some local agencies to posess it. It's not all that hard to get, if you have a good reason to have it (safety devices on a rocket is a very good reason...), but you have to be real careful about handling explosives, and can't store them just anywhere (there's a big table of how far from any inhabited buildings or roads a storage bunker has to be, based on how much explosives are in it). I'm not going to need any until the rocket is nearly ready to fly, and don't need the hassle of finding somewhere to store it until then... and definitely, setting it off in your back yard is a no-no. -george william herbert ------------------------------ From: gwh@lurnix.COM (George William Herbert) Date: Wed, 09 Dec 92 12:22:17 -0800 To: space-tech@cs.cmu.edu Cc: gwh@lurnix.COM Subject: Pressurizing Tanks Self_Organization: Retro Aerospace, (510) 849-4853 Work_Organization: Lurnix, (510) 849-4478 x229 fax (510) 849-0409 X-Funny-Message-Of-Day: When you absolutely, positively, don't want pumps... Having perused through some (10%) of the material I got from my friend at NASA on hybrids, I've come across at least one useful thing... how they want to pressurize at least two of the proposed hybrid vehicles. They were discussing using a mixture of helium (most) and a little stoichiometric mix of oxygen and hydrogen. Apparently, if you keep the H2/O2 percentages low enough, it won't normally burn, but if you pass it over a catylist bed the stuff heats up and expands quite a bit. As soon as I dig some more info on it up I'll post it. -george william herbert ------------------------------ End of Space-tech Digest #140 *******************