 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| HomeDiscussion GroupsSpace ScienceAstronomyAmateur AstronomySpace FlightSpace StationShuttleSpace HistorySpace PolicySETI SpaceKB.com Contact UsLink To UsSearch & Site Map |
Space Forum / Space Flight / January 2004Simple large solid.
Would it be possible to build one enormous single stage solid launcher and offset the cost of the quantities involved by the saving on the technological costs of multi-stage elements in a conventional launcher? What I mean is, an oversized "Minuteman" type with a guidance (payload)head using transverse thrusters to control it's attitude? I'm looking at the low cost of propellant materials in enormous quantity. There would be a payoff in reliability due to the simplicity of the system. TIA << Would it be possible to build one enormous single stage solid launcher >><BR><BR> There's a limit to how large you can pour a solid-fuel stage. Make it too large, and the grain will crack from internal stresses as the rubbery material cools and settles. I forget the size of the largest one ground-tested, but it's hard to believe you could make one bid enough for SSTO with significant payload. Matt Bille (MattWriter@AOL.com) OPINIONS IN ALL POSTS ARE SOLELY THOSE OF THE AUTHOR > << Would it be possible to build one enormous single stage solid launcher > >><BR><BR> > > There's a limit to how large you can pour a solid-fuel stage. Make it too > large, and the grain will crack from internal stresses as the rubbery material > cools and settles. I forget the size of the largest one ground-tested... 260-inch diameter. Aerojet.  SignatureScott Lowther, Engineer Remove the obvious (capitalized) anti-spam gibberish from the reply-to e-mail address > << Would it be possible to build one enormous single stage solid launcher > >><BR><BR> [quoted text clipped - 4 lines] > it's hard to believe you could make one bid enough for SSTO with significant > payload. So instead of making a single-pouring stage that is hollow and burns from the inside out, pour a number of solid columns that burn from the outside in and are bundled in one large casing. > << Would it be possible to build one enormous single stage solid launcher > >><BR><BR> [quoted text clipped - 8 lines] > (MattWriter@AOL.com) > OPINIONS IN ALL POSTS ARE SOLELY THOSE OF THE AUTHOR What experiments have been done to examine incorporating some sort of fiber reinforcement into the grain to prevent cracking? How about the obvious: carbon fiber? >> There's a limit to how large you can pour a solid-fuel stage. Make it too >> large, and the grain will crack from internal stresses... > >What experiments have been done to examine incorporating some sort of >fiber reinforcement into the grain to prevent cracking? How about the >obvious: carbon fiber? Carbon fiber in particular is probably a bad choice, because it's quite a good thermal conductor, and solid fuels want low thermal conductivity (partly to insulate the outer case, partly to concentrate combustion heat near the inner fuel surface to encourage the surface to boil off). I think fiber reinforcement of solid fuels has been done, but the mass penalty is substantial if you want good reinforcement. SignatureMOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | henry@spsystems.net > >> There's a limit to how large you can pour a solid-fuel stage. Make it too > >> large, and the grain will crack from internal stresses... [quoted text clipped - 10 lines] > I think fiber reinforcement of solid fuels has been done, but the mass > penalty is substantial if you want good reinforcement. Ah, I hadn't thought about the thermal conductivity of carbon fiber being an issue. I suggested carbon fiber mainly because I've been laying up some parts out of it lately and it was on my mind. It did belately occur to me that the mass of fibers required to achieve reinforcement might be significant. I wonder if fibers could be made out of something that would be a relatively efficient fuel as well as provide reinforcement? On second thought, that ain't gonna work as the fuel and oxidizer need to be mixed at a very fine scale. I guess a fibrous fuel grain embedded in a fuel matrix might be a good idea in a really big hybrid motor (can the phrase "good idea" even be used in the same conversation "big hybrid motor"?). >> >What experiments have been done to examine incorporating some sort of >> >fiber reinforcement into the grain to prevent cracking? How about the [quoted text clipped - 17 lines] >provide reinforcement? On second thought, that ain't gonna work as the >fuel and oxidizer need to be mixed at a very fine scale. The larger the motor, the less finely the ingredients have to be mixed. But they still do have to be mixed, and I think this, rather than the mass penalty, would be the main difficulty with fiber reinforcement. Solid rocket mixes are usually upwards of 80 percent oxidizer, and mixing 80 percent of solids into 20% of rubber binder is a very difficult task. If, for instance, the oxidizer were composed of perfect spheres all of the same size, it would be impossible to make such a mix; a perfect packing of spheres has more than 20% space between them. Just for it to be possible, you need oxidizer that has a mixture of different particle sizes, so that the small particles can fill in the spaces around the big ones. And possible does not mean easy: even uncured, the rubber binder is viscous stuff, and once you start mixing it there is a limited time available before it starts to cure. For good burning, the batch has to be very well mixed, and with no bubbles. All these difficulties have been overcome; but that does not mean that they would still be surmountable if you threw a load of Kevlar fibers into the mix; for starters, the fibers would quickly clog the paddles of your mixer. If you kept the fibers really short, maybe you could get away with mixing them; but then you'd have to worry about what their orientation turned out to be, in the poured grain, and you might well have to include so many of them that their mass would be a significant factor. If you try to use the fibers as fuel, then their mass reduces the amount of rubber you can use, which makes the mixing even harder. SignatureNorman Yarvin norman.yarvin@snet.net > << Would it be possible to build one enormous single stage solid launcher > >><BR><BR> [quoted text clipped - 8 lines] > (MattWriter@AOL.com) > OPINIONS IN ALL POSTS ARE SOLELY THOSE OF THE AUTHOR Back in the Sixties before the Saturn was chosen for Apollo, Aerojet proposed a gigantic first stage for the Nova that was simply a big solid fuel booster. Instead of pouring the fuel like they do for Shuttle, a bunch of guys would swarm into the thing and lay solid fuel blocks inside it with an adhesive like construction workers laying cinder block for a house foundation. I have no idea what the concept was called or any technical references. It seems to me there was something about it in the main American Rocket Society public -ation about 1959 (before it became the AIAA). The thing was as big as Sea Dragon and it may have been one of Bob Truax's ideas. Sorry that's all I remember. > << Would it be possible to build one enormous single stage solid launcher > >><BR><BR> [quoted text clipped - 4 lines] > it's hard to believe you could make one bid enough for SSTO with significant > payload. The largest ever tested was the Aerojet monolithic 260-inch-diameter solid. These were about twice the diameter and mass of the shuttle's solids. The problem is that SSTO requires really high Isp combined with very high mass fractions. Solid motors can achieve neither. For instance, the full-length 260-inch Aerojet solid motor (never built) would have been a long way from SSTO even with no payload at all - with no second stage, delta-vee would be around 5.5 km/s, not much more than half of orbital speed. Gee loading would be substantial, at 23! Regards, Jonathan Wilson > Would it be possible to build one enormous single stage solid launcher and > offset the cost of the quantities involved by the saving on the > technological costs of multi-stage elements in a conventional launcher? The two problems you run into with *solid* single-stage-to-orbit (SSTO) launchers are: 1) Fuel efficiency. Solids have low fuel efficiencies for the thrust they provide, and rockets demonstrate a nasty exponential weight increase with decreasing fuel efficiency. For example, a good, single-staged liquid fueled rocket might put 1 kilogram (cargo and spaceship both) into orbit for every 10 kilograms of launch mass; in other words, 9kg of fuel are needed for every kilogram of spaceship. On the other hand, a decent solid fueled rocket will put 1kg into orbit for every ~30kg of launch mass. In other words, the solid fueled rocket needs 29kg of fuel per kilogram of spaceship and cargo. But then there's the next problem, which makes it unlikely solids will manage that 29:1 ratio. 2) Dry mass. Solid fueled rockets are thick-skinned, heavy critters because the entire body of the rocket is the combustion chamber. The walls of the shuttles' SRBs are 1-2cm stainless steel, IIRC. Their empty, unfueled, cargo-free mass is about 15% of their fully loaded mass; the shuttles' SRBs are ~580 tons, of which ~500 tons is fuel. 500:80 (6.25:1) far short of 29:1. Even the best liquid fueled rockets cannot get to orbit with a single stage and 6.25:1 fuel:dry mass ratio. On the other hand, liquid fueled rockets can have very thin-skinned fuel tanks and can approach or exceed 10:1 mass ratios. Barely. It's easier to use a second stage and more generous mass ratios. So my answer to your question is "probably not." You'd have a better chance with big, single stage liquid fueled vehicles. > I'm looking at the low cost of propellant materials in enormous quantity. Then you'll want to consider liquid fuels. *Liquid oxygen is much cheaper than soda, bottled water, or gasoline. I think LOX goes for about $0.08 per liter (~$0.30 per gallon) when purchased in bulk. Individual steel plants with 1 megaton of annual steel production use around 500 tons of LOX per day; the demands of rocket launches (600 tons of LOX per shuttle launch) are a drop in the bucket of annual LOX production. *Kerosene can be had (in bulk) at about $0.60 to $0.80 per gallon, I think. If I did the conversions right, US airlines were using something like 200000 tons of kerosene (jet fuel) per day in 2000AD. It would take a lot of rocket launches to match airlines' usage. *Liquid hydrogen is about $4 per kilogram, but a kilogram of liquid hydrogen is close to 4 gallons. *I'm not sure of the pricing of solid fuels, but the ability to quickly order millions of gallons of inexpensive liquid oxygen, kerosene, and/or hydrogen from commercial vendors is attractive. Solid fuels are not so easily shipped and pumped into the rocket. Mike Miller, Materials Engineer >There would be a payoff in reliability due to the simplicity of the system. I've never considered solids that simple. Sure thay look simple, but try making one, then try making a big one. To first order approximation a solid is a pressure feed liquid with a oversized combustion chamber(and all that it implies) and under performing fuel combinations. And i left out the part were its kinda a big stick of dynamite. Hybrids are better, but SSTO will be a liquid fueled rocket. Solids are best left for the military applications thay were orginaly devloped for. IMHO of course. Greg gewi001@phy.auckland.ac.nz (Greg) : > > >There would be a payoff in reliability due to the simplicity of the [quoted text clipped - 13 lines] > > IMHO of course. Would like to point out that H2O2(liquid) and AlH3(solid) has a ISP over 550s. This suggest a hybrid can be a SSTO. Earl Colby Pottinger SignatureI make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos, SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to the time? http://webhome.idirect.com/~earlcp Earl Colby Pottinger <earlcp@idirect.com> wrote in message > Would like to point out that H2O2(liquid) and AlH3(solid) has a ISP over > 550s. This suggest a hybrid can be a SSTO. is that a demonstrated Isp. Two phase flows will hit it really hard. Greg Earl> Would like to point out that H2O2(liquid) and AlH3(solid) has a ISP over Earl> 550s. This suggest a hybrid can be a SSTO. With H2O2? Reference? How does LOX and AlH3 look? It must be absolutely ridiculous. Why isn't this listed along with the other ridiculous combinations (Li+H+F) in the various books? iain-3@truecircuits.com (Iain McClatchie) : > Earl> Would like to point out that H2O2(liquid) and AlH3(solid) has a ISP > over [quoted text clipped - 5 lines] > this listed along with the other ridiculous combinations (Li+H+F) in the > various books? Good reason to always look at your references before posting in a sci.* group. Check out http://www.armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=140 ISP of 424, not 500+ Earl Colby Pottinger SignatureI make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos, SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to the time? http://webhome.idirect.com/~earlcp > iain-3@truecircuits.com (Iain McClatchie) : > [quoted text clipped - 15 lines] > > Earl Colby Pottinger I did finally get a price quote for some aluminum hydride from hydridetech.com: $8,000 / kg !!! It is only produced in lab quantities at the moment, they said that industrial production at tons / year would reduce price by a factor of 10. Still waaay to expensive. Before I got that number, I had a related idea that is enticing in a terrifying sort of way -- AlH3 has a density of 1.48 g/cc, and 98% peroxide has a density of 1.44 g/cc. AlH3 is not hygroscopic, and is stable to 150 C. If you mixed powdered AlH3 into 98% peroxide, it would not dissolve, and the densities are close enough that the powder would stay suspended for quite some time. A monopropellant slurry with a density-Isp of over 600. It would only take modest modifications to our X-Prize vehicle to make an SSTO filled with that. Probably fearfully explosive, but it would be worth some carefull testing to see... John Carmack >...If you mixed powdered AlH3 into 98% peroxide... modest >modifications to our X-Prize vehicle to make an SSTO filled with that. > Probably fearfully explosive, but it would be worth some carefull >testing to see... The mere suggestion is enough to make me want to dive for cover. :-) Especially since, if memory serves, the standard preparation process for AlH3 leaves some organic solvent in it. SignatureMOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | henry@spsystems.net .. > I did finally get a price quote for some aluminum hydride from > hydridetech.com: [quoted text clipped - 4 lines] > industrial production at tons / year would reduce price by a factor of > 10. Lab quantities == lab purity? Even technical grade is probably way more than is actually necessary for a rocket propellant, depending on the specific impurities. I wonder how far the price might go down if the specification allows, for example, up to 5% aluminum, catalyst residues, etc. IANACE > gewi001@phy.auckland.ac.nz (Greg) : > > > > >There would be a payoff in reliability due to the simplicity of the [quoted text clipped - 13 lines] > > > > IMHO of course. > Would like to point out that H2O2(liquid) and AlH3(solid) has a ISP over > 550s. This suggest a hybrid can be a SSTO. > Earl Colby Pottinger That seems difficult to believe, are you sure of that number? I plugged it into my handy-dandy Air Force ISP calculator and the best I could get was around 490 (still pretty amazing) and that was at ridiculous chamber pressure and expansion ratio (Pchamber = 5000 PSIA, Pexhaust = .001 PSIA). At more rational parameters (Pchamber = 1000 PSIA, Pexhaust = .1 PSIA) I get "only" 439 seconds, still pretty respectable for a dense propellant combination (density=1.436). I tried it with oxygen instead of H2O2 and it did worse not better (429s, density=1.287 with Pchamber=1000 PSIA, Pexhaust=.1 PSIA). I'm not sure why LO2 is worse than H2O2, perhaps a higher average molecular weight exhaust and not enough gaseous products to suck the heat out of the (solid) Al2O2? The exhaust temp of the AlH3/O2 combo is really high (2440 K). In both cases there is quite a bit of H2 in the exhaust. Jon Watts Jon Watts <First_Last@hp.com> : > Earl Colby Pottinger <earlcp@idirect.com> wrote: > > gewi001@phy.auckland.ac.nz (Greg) : [quoted text clipped - 38 lines] > > Jon Watts You are right and I am wrong. When I double-checked my reference and did a google search the number I should have reported was ISP of 424. Earl Colby Pottinger SignatureI make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos, SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to the time? http://webhome.idirect.com/~earlcp > Would it be possible to build one enormous single stage solid launcher and Aren't solid rocket firings pretty polluting, so replacing Hydrogen/Kerosene rockets with solid rockets by the hundreds might might do bad things to ozone, launch site, etc. Just a thought. > > Would it be possible to build one enormous single stage solid launcher and > > Aren't solid rocket firings pretty polluting, so replacing > Hydrogen/Kerosene rockets with solid rockets by the hundreds might > might do bad things to ozone, launch site, etc. Just a thought. Regarding pollution, the problem is ammonium perchlorate (AP). No AP, no problem. |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.