hop - 24/4/2006 6:49 PMQuoteTap-Sa - 24/4/2006 7:59 AMWhy didn't the Russians choose big SRMs? And ship them in pieces from Baikonur to ... Kamchatka for reload by Thiokolvskiya. The most often cited reason is that there was no Thiokolvskiya! Russia lacked experience with large segmented solids. Even their large ICBMs were liquid fueled. Glushko, who was by then the chiefest of the chief designers, was a liquids guy. Also, even when they planned to recover the boosters (they were never actually re-used AFAIK), they planned to do so on land, so the issues are different.
Tap-Sa - 24/4/2006 7:59 AMWhy didn't the Russians choose big SRMs? And ship them in pieces from Baikonur to ... Kamchatka for reload by Thiokolvskiya.
publiusr - 29/4/2006 4:38 PMQuotehop - 24/4/2006 6:49 PMQuoteTap-Sa - 24/4/2006 7:59 AMWhy didn't the Russians choose big SRMs? And ship them in pieces from Baikonur to ... Kamchatka for reload by Thiokolvskiya. The most often cited reason is that there was no Thiokolvskiya! Russia lacked experience with large segmented solids. Even their large ICBMs were liquid fueled. Glushko, who was by then the chiefest of the chief designers, was a liquids guy. Also, even when they planned to recover the boosters (they were never actually re-used AFAIK), they planned to do so on land, so the issues are different. They were better off focusing on liquids. They serve the LV market better.If Oural is more than a dream--it will likely be kerolox--so we may never see hydrogen at Kourou for anything other than upper stages.The former Soviets have replaced the Germans in setting standards for liquid fueled excellence--while we focused on tiny solids with tiny warheads, the bigger rocket =better rocket philosophy from the Russians (who had no fear of large LVs) won the day--and the markets.We could have gone that route, but didn't. We got better ICBMs out of the solids, yes--but they have better space carrier rockets.
BarryKirk - 6/5/2006 4:36 PMWhy is everybody so interested in a flyback first stage? For every pound of flyback equipement on board, the mass of the upper stages needs to be reduced by onepound. The cost of putting flyback equipement on board is very expensive. How about a bare bones, just enough TPS as needed and a parachute? Bring the vehicleback by pulling it out of the drink.You don't need fuel, landing gear, wings, and flyback engines.
BarryKirk - 6/5/2006 9:36 AMWhy is everybody so interested in a flyback first stage? For every pound of flyback equipement on board, the mass of the upper stages needs to be reduced by one pound. The cost of putting flyback equipement on board is very expensive. How about a bare bones, just enough TPS as needed and a parachute? Bring the vehicle back by pulling it out of the drink.You don't need fuel, landing gear, wings, and flyback engines.
Tap-Sa - 23/4/2006 10:23 AMWhy NASA is so bent on using solids as or paraller with first stage is beyond me. Thinking seem to have changed radically since Von Braun's times. I bet CLV plans cause considerable spinning in his coffin. Solids guarantee a very rough ride to those who end up riding those beasts. They also guarantee a much bigger bang when motor fails. Why is this? When rocket engine 'blows up' it usually means the reaction chamber, a pressure vessel with hole (throat), disintegrates. Energy released is proportional to the pressure and volume of contained gases. SRB is basically just a big reaction chamber, thus it contains orders of magnitude more high pressure gas during operation than liquid engines. But, as in many other threads it has been pointed out, NASA decisions are more political, less technical.
tom nackid - 8/5/2006 3:58 PMQuoteTap-Sa - 23/4/2006 10:23 AMWhy NASA is so bent on using solids as or paraller with first stage is beyond me. Thinking seem to have changed radically since Von Braun's times. I bet CLV plans cause considerable spinning in his coffin. Solids guarantee a very rough ride to those who end up riding those beasts. They also guarantee a much bigger bang when motor fails. Why is this? When rocket engine 'blows up' it usually means the reaction chamber, a pressure vessel with hole (throat), disintegrates. Energy released is proportional to the pressure and volume of contained gases. SRB is basically just a big reaction chamber, thus it contains orders of magnitude more high pressure gas during operation than liquid engines. But, as in many other threads it has been pointed out, NASA decisions are more political, less technical.On the contrary, large solids in parallel were planned as an upgrade for Von Braun's Saturn V. And of course the Air Force has used large solids in Titans for years. In fact the Titan IV launched on solids only I believe.Small solid rockets blow up because chunks of propellant break off and block the throat. This is far less likely to happen on larger solids--at least according to people who's job it is to study failure modes in solid rockets.
tom nackid - 8/5/2006 3:58 PMSmall solid rockets blow up because chunks of propellant break off and block the throat. This is far less likely to happen on larger solids--at least according to people who's job it is to study failure modes in solid rockets.
aero313 - 8/5/2006 9:04 PMQuotetom nackid - 8/5/2006 3:58 PMSmall solid rockets blow up because chunks of propellant break off and block the throat. This is far less likely to happen on larger solids--at least according to people who's job it is to study failure modes in solid rockets.Boy, is that an uninformed and incorrect statement. The last failure of a small solid that I'm aware of is the Delta II/GPS mission in Jan 1997. The actual failure was attributed to damaged graphite fibers on the case of one of the solids, resulting in a case failure due to internal pressure. Titans have failed due to cracks in the propellant that resulted in hot gas reaching the case and burning through. I'm not aware of ANY solid rocket motor failures, large or small, attributed to "blocked throats". The CONTOUR spacecraft failure of the Star motor was at first attributed to a blocked throat, but in reality was caused by an incorrect thermal design that buried the motor too far inside the spacecraft, resulting in structure overheating and failure during burn.I certainly invite you to list the failures that "these people" attribute to propellant chunks in the throat.
Jim - 8/5/2006 9:15 PMOne SRMU did on a test stand at EAFB. But that is only one, you are correct.
Tap-Sa - 23/4/2006 8:23 AMHydrocarbons are the practical first stage fuel, but the sad fact is that after Saturn V NASA completely forgot how to make good HC engines. The shuttle was supposed to solve everything, no need to fool around with anything else. Well it didn't. And now would have been a great time to dig up F-1A (or maybe F-1C, F-1D etc) plans for CaLV, if only the previous people at NASA helm would have had the 'waste not' attitude and allocated a few dimes to keep those engine plans updated to the latest design/manufacturing methods. But noo, politics required tunnel vision.(Sorry if this answer reeks too much 'solids suck' attitude. But IMO they do
Tap-Sa - 23/4/2006 9:10 AMWhy NASA is so bent on using solids...edit: And about hypergolics, Russia and China can still use them in a large scale because these anarchocapitalist and communist nations couldn't care less about environmental issues. NTO/UDMH raining from the sky means a real bad day. AFAIK their usage in large boosters is banned in US, and rightly so.
Tap-Sa - 23/4/2006 2:05 PMKerosene, being a long complex chain of C and H, can produce all sorts of 'interesting' partially burned stuff. Kerosene will also coke ie. molecules get clued together, if it gets too hot too soon (in coolant pipes). If it happens too much tar will come out of the injector instead of kerosene. Hydrogen won't coke, nor simpler hydrocarbons, especially methane.Another thing is the rate at which burning happens. Hydrogen, being a simple two atom molecule, burns fast. Fast burning means propellants don't need to linger inside the combustion chamber very long, therefore it can be smaller. In methane, the carbon really wants to keep the four hydrogen atoms it gots. This is good thing in the cooling pipes, methane doesn't break prematurely and coke, but in the combustion chamber it means that it takes some time to eventually break the molecule so that LOX can combine with the parts.
BarryKirk - 6/5/2006 8:23 AMWhy is everybody so interested in a flyback first stage? For every pound of flyback equipement on board, the mass of the upper stages needs to be reduced by onepound. The cost of putting flyback equipement on board is very expensive. How about a bare bones, just enough TPS as needed and a parachute? Bring the vehicleback by pulling it out of the drink.You don't need fuel, landing gear, wings, and flyback engines.
josh_simonson - 8/5/2006 4:16 PMThe first stage of the falcon 1 is probably light enough that a heavy helicopter could catch it in mid-air and return it in pristine condition.