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#21
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In article .com,
Ed Kyle wrote: ...He said that the Northrop/Boeing's CEV design could be launch by *existing* Delta IV vehicles. That does not jive with pronoucements made by both Griffin and ATK officials that the EELVs would need new upper stages (just like "The Stick") to lift CEV. It could be that the Northrop/Boeing CEV design is not as elephantine as a certain other contractor's design. ATK is hardly a disinterested observer. Griffin is harder to call -- he may just be assuming worst-case CEV mass, or he (like ATK) may have a preferred solution in mind and may be picking the numbers which support it best. -- "Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | |
#22
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From: h (Rand Simberg) Yes, I suspect that the only thing that they can really use from the existing ET program is the barrel sections. Otherwise, it's really a new tank. You don't think they'll need more wall thickness in that area? Phil |
#23
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"Murray Anderson" wrote in message ... "Ed Kyle" wrote in message oups.com... Brian Thorn wrote: Well, these pretty pictures are all definitely for public relations and politics, not engineering. But you can easily make the same claim about the LockMart Atlas-5 based heavy-lifter in this week's AvLeak. At least for the SDLV, all the essential elements have either been tested or are in service, even the 5-segment SRB. The Atlas 5 Super Heavy seems to require new tooling for a wider core stage and a new pad to launch it from. That part of that AWST issue that I found most interesting was the statement attributed to Boeing VP Chuck Allen. He said that the Northrop/Boeing's CEV design could be launch by *existing* Delta IV vehicles. That does not jive with pronoucements made by both Griffin and ATK officials that the EELVs would need new upper stages (just like "The Stick") to lift CEV. - Ed Kyle If it's a 20 ton CEV Delta IV should have no problem, with 25 tons it would probably need twin RL10's and an upper stage with more propellant than the small Delta IV upper stage, but less then the large upper stage. It's the same with the SRB launcher, the 20 ton might get away with a J2 engine, but 25 tons would require an SSME. This is a bait-and-switch type situation, whereby a nonexistent launcher with J2/SSME is proclaimed better than an existing launcher that needs a comparatively minor upgrade to the upper stage - then we learn that only the SSME (with extended nozzle, and altitude start capability) will work, and the lower stage will require a bit of work to make the steering function in a highly unstable design. You hit the nail on the head. The Stick is basically the Ariane 5 without the upper stage. Except the Ariane 5 can not out lift the Atlas or Delta Heavies. |
#24
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Ed Kyle wrote:
Brian Thorn wrote: Well, these pretty pictures are all definitely for public relations and politics, not engineering. But you can easily make the same claim about the LockMart Atlas-5 based heavy-lifter in this week's AvLeak. At least for the SDLV, all the essential elements have either been tested or are in service, even the 5-segment SRB. The Atlas 5 Super Heavy seems to require new tooling for a wider core stage and a new pad to launch it from. That part of that AWST issue that I found most interesting was the statement attributed to Boeing VP Chuck Allen. He said that the Northrop/Boeing's CEV design could be launch by *existing* Delta IV vehicles. That does not jive with pronoucements made by both Griffin and ATK officials that the EELVs would need new upper stages (just like "The Stick") to lift CEV. - Ed Kyle Yes. The original CEV requirements were written so that existing launchers could be used. That was kinda the point of OSP and CEV. Limit the development costs by focussing on one area and examine exactly what they need, not necessarily what they want. Even then CEV was a lot heavier than other manned vehicles in roughly the same class. (To date, IIRC, the only operational manned vehicles to weigh in over 10 tons is Shuttle and the lunar lander. That is separating Apollo CM from the Service module. I count the lunar module with its lander as one piece as it was the minimal mass for its job, whereas the Service Module in the CSM varied greatly in mass dependant upon its mission. I *think* they might have used ASTP as the planning mass for the CEV). Looking at http://www.astronautix.com/craft/cev.htm The CEV requirements included: * Support a minimum crew of four from the Earth's surface through mission completion on the Earth's surface. * Mass less than 15 to 18 tonnes (the precise value to be determined in preliminary contract studies). * Abort capability during all phases of flight. Preferably such abort capability would be available continuously and independent of Launch Vehicle (LV) or Earth Departure Stage (EDS) flight control. * Integrate with the Constellation Launch Vehicle (LV) to achieve low earth orbit. * Integrate with the Earth Departure Stage (EDS) to achieve lunar orbit. * Integrate with the Lunar Surface Access Module (LSAM) to achieve lunar surface mission objectives. Preferably the CEV would be capable of transferring consumables to and from the EDS and the LSAM. * Maximum use of existing technology. * Open Systems Architecture. Referral common hardware and software between equipment built for acceptance testing of the flight system and the ground support equipment used to process the vehicle at the launch site. * Simple interface between the CEV and Launch System to optimise integration. * Certification by test to the maximum extent possible. seriously, the requirements are approximately identical to the one for the Apollo CM with a LEO Service Module component. The ASTP Apollo CSM massed about 15000kg, and there is a oof of weight that could be trimmed off that. When you start to see numbers double demonstated technologies 40 years old, alarm bells start ringing. These guys have an agenda that is not on the paper in front of them. Flat out: The SDLV being proposed for CEV violates the maximum use clause. The requirements originally put out there as well as historical evidence is that this can be done in the EELV range. If you can do the CEV proposal on all existing launch hardware and be able to concentrate additional development on the CEV itself, then you have very little ancillary costs and those would be associated with mating issues. But, to build both CEV and launch vehicle splits the money available. It also fudges quite a bit on that "abort on all phases" clause as SRB's abort stages tend to be "but the crew was killed" type aborts. Nah, I think politics won. They have a predetermined technical solution and they are going to make sure it wins. |
#25
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"Ed Kyle" wrote in message oups.com... Brian Thorn wrote: Well, these pretty pictures are all definitely for public relations and politics, not engineering. But you can easily make the same claim about the LockMart Atlas-5 based heavy-lifter in this week's AvLeak. At least for the SDLV, all the essential elements have either been tested or are in service, even the 5-segment SRB. The Atlas 5 Super Heavy seems to require new tooling for a wider core stage and a new pad to launch it from. That part of that AWST issue that I found most interesting was the statement attributed to Boeing VP Chuck Allen. He said that the Northrop/Boeing's CEV design could be launch by *existing* Delta IV vehicles. That does not jive with pronoucements made by both Griffin and ATK officials that the EELVs would need new upper stages (just like "The Stick") to lift CEV. Based on Boeing's program proposal at: http://exploration.nasa.gov/documents/cer_reports.html Which may or may not be accurate reference for Northrops CEV. The CEV comes in at 20 tons including 7.8 tons of fuel and an escape system. With only the fuel needed for ISS that would be about 13 tons including an escape tower. That is a Delta IV 5,4. Even 20 tons can be done on single stick models if you use 2 RL-10s. The entire thing seems to way in around 45 tons which a 125 ton LEO vehicle with an upper stage can put in Lunar orbit. |
#26
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Rand Simberg wrote:
Yes, I suspect that the only thing that they can really use from the existing ET program is the barrel sections. Otherwise, it's really a new tank. They just need enough structure to transmit the thrust to the intertank area, which is designed to handle the combined thrust loads from the orbiter and both solids. The LH2 tank essentially "hangs" from the intertank during launch -- the rear orbiter and SRM supports don't see any significant thrust loads. It may be as simple as a change in the milling that's done on the ET skin sections (removing less) to add (or strengthen) the existing truss-like structure in the LH2 skin. Another, "Goldbergian" solution could be to add a lattice structure that extends from the thrust "module" and extends the length of the LOX tank to the intertank. Since you can also reduce the SOFI thickness (you no longer care so much about ice, but just boil-off), the weights may trade off. Propellant lines can remain essentially the same -- just re-direct them to an interface on the (likely) thrust assembly below the ET that holds the SSMEs. The lines are obviously large enough for a 3 SSME booster -- since you've eliminated the pressure drop caused by the current sharp right-angle turn into the orbiter, the lines may actually be adequate for a 4 SSME booster. Add a lengthened cylinder above the intertank that rises above the LOX tank, and you're done -- assuming that you add a "droppable" interstage like the S-II's to compensate for the length of the upper stage's engines & the exhaust bells. Since the booster's SSME's no longer have to fit in the re-entry shadow of the shuttle, do you change the nozzle and/or bell geometry? Do we need to air-start the SSMEs (a la Titan III & IV), or just light everything off on the ground the way we do now? Reed -- I was punching a text message into my | Reed Snellenberger phone yesterday and thought, "they need | GPG KeyID: 5A978843 to make a phone that you can just talk | rsnellenberger into." Major Thomb | -at-houston.rr.com |
#28
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"Jorge R. Frank" wrote:
Well, these pretty pictures are all definitely for public relations and politics, not engineering. But you can easily make the same claim about the LockMart Atlas-5 based heavy-lifter in this week's AvLeak. At least for the SDLV, all the essential elements have either been tested or are in service, even the 5-segment SRB. Well, except for the ET. The current ET is designed to absorb loads along the side through the intertank (orbiter and SRB forward attach points) and the aft ring (orbiter and SRB aft attach points). The SDLV ET will have to take thrust loads through the bottom of the tank, and to take the weight of the payload from the top (which will also necessitate redesigning the LOX tank ogive). That depends on which version of the SDLV you look at. The first two on the chart[1] use standard ET's, only the third requires modifications. [1] see: http://www.safesimplesoon.com/assets.../evolution.jpg from http://www.safesimplesoon.com/media-images.htm D. -- Touch-twice life. Eat. Drink. Laugh. -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL |
#29
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On 26 Jun 2005 10:01:14 -0700, in a place far, far away, "Ed Kyle"
made the phosphor on my monitor glow in such a way as to indicate that: Brian Thorn wrote: Well, these pretty pictures are all definitely for public relations and politics, not engineering. But you can easily make the same claim about the LockMart Atlas-5 based heavy-lifter in this week's AvLeak. At least for the SDLV, all the essential elements have either been tested or are in service, even the 5-segment SRB. The Atlas 5 Super Heavy seems to require new tooling for a wider core stage and a new pad to launch it from. That part of that AWST issue that I found most interesting was the statement attributed to Boeing VP Chuck Allen. He said that the Northrop/Boeing's CEV design could be launch by *existing* Delta IV vehicles. That was their original design goal. That does not jive with pronoucements made by both Griffin and ATK officials that the EELVs would need new upper stages (just like "The Stick") to lift CEV. They obviously have different notions. |
#30
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From: Reed Snellenberger They just need enough structure to transmit the thrust to the intertank area, which is designed to handle the combined thrust loads from the orbiter and both solids. The LH2 tank essentially "hangs" from the intertank during launch -- the rear orbiter and SRM supports don't see any significant thrust loads. It may be as simple as a change in the milling that's done on the ET skin sections (removing less) to add (or strengthen) the existing truss-like structure in the LH2 skin. Another, "Goldbergian" solution could be to add a lattice structure that extends from the thrust "module" and extends the length of the LOX tank to the intertank. Since you can also reduce the SOFI thickness (you no longer care so much about ice, but just boil-off), the weights may trade off. Propellant lines can remain essentially the same -- just re-direct them to an interface on the (likely) thrust assembly below the ET that holds the SSMEs. The lines are obviously large enough for a 3 SSME booster -- since you've eliminated the pressure drop caused by the current sharp right-angle turn into the orbiter, the lines may actually be adequate for a 4 SSME booster. Add a lengthened cylinder above the intertank that rises above the LOX tank, and you're done -- assuming that you add a "droppable" interstage like the S-II's to compensate for the length of the upper stage's engines & the exhaust bells. Since the booster's SSME's no longer have to fit in the re-entry shadow of the shuttle, do you change the nozzle and/or bell geometry? Do we need to air-start the SSMEs (a la Titan III & IV), or just light everything off on the ground the way we do now? Reed This is going to need a fair bit of re-engineering anyway, it sounds like... Why not go all the way and put the oxygen tank on the *bottom*? Phil |
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