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Space Forum / Shuttle / May 2006CEV in disarray???? From space news........
Nasa keeps getting more muddled.... Put CEV on expendable and build shuttle C for cargo using existing shuttle form.... CEV Update April 16, 2006 This coming week is a time of decision for the CEV/CLV program. We are back to a 4 segment SRB. The 5 segment SRB 1st stage required an additional $1,000,000,000 next year to certify for flight. They wanted to change the propellant grain. This was driving a full test program and a massive amount of analysis. Simple put, the SRB program was starting over. We may add a second J-2 engine to the upperstage of the CLV to get more energy. However we can't make the 2nd stage much wider or the SRB will snap. The option to add a third stage to the CLV is out. A three stage CLV would not fit out the VAB doors. The Launch Abort Rocket design is fixed. It looks and works like the escape rocket on the Soyuz. This allow us to fly without a booster cover on the CEV capsule. Right now we can't fly the Lunar CEV SM and CM on one CLV rocket so the new plan is called "Lunar 2.5". We launch the CEV service module (minus the CEV capsule) on a CLV 1st. Followed in a day to two by a CEV Command Module and crew (minus the SM) launched by a second CLV. The CM rendezvous and docks the with SM. Followed the next day with launch of the heavy lift (HLV) booster with the earth departure stage and Lunar Lander. They all form up and away we go! One more idea from this week you might find interesting. Cancel the CLV and man rate the HLV. That will most likely not happen. It should, saves a ton of cash and gets us to one design. One more new bit. Two SRB's, one on each side of the new upperstage. Looks a lot like the Shuttle C concept with the CEV on top. Could happen. Solves the energy problem. But, it's not Monday yet. Lastly the ISS CEV will have very small version of the SM (sort of a limited propulsion module). Just a comment here... Shuttle at the moment is seen as vulnerable hence all the repair, rescue mission safe haven stuff, but nobody has applied this logic to the Lunar landing, nor did they to Apollo, so if the one engine failed on the moon, you is dead. So, should we not be building an automated habitat for the landing site of at least the first moon mission? Or is it fine to lose crew on the moon, but not in Shuttle? I guess the bottom line is that Space, in the current state of the art is dangerous for humans, and although obviously we need to do all we can to keep people safe, it will always be a trade off against results, and if you want 100 percent safety, you is living in a fantasy world. Just being logical... Brian  Signaturebriang1@blueyonder.co.uk From my IMAP account Brian Gaff > Nasa keeps getting more muddled.... > [quoted text clipped - 42 lines] > CEV will have very small version of the SM (sort of a limited > propulsion module). > Shuttle at the moment is seen as vulnerable hence all the repair, rescue > mission safe haven stuff, but nobody has applied this logic to the Lunar > landing, nor did they to Apollo, so if the one engine failed on the moon, > you is dead. Um, from what I remember the ascent engine was hypergolically fuelled with multiple redundancy everywhere: making it kind of unlikely to fail. Couldn't it even be worked on by the crew from inside the LEM if it did manage to fail? Mark Link or source please. > Nasa keeps getting more muddled.... > [quoted text clipped - 42 lines] > CEV will have very small version of the SM (sort of a limited > propulsion module). http://www.usspacenews.com/ sorry i always try to link my sources! >However we can't make >the 2nd stage much wider or the SRB will snap. How does an SRB snap? Seems a little stout for that... there must be structural limits SRBs are big and wide looking but are primaarily propellant, old pieces are discarded ffor getting out of round >there must be structural limits SRBs are big and wide looking but are >primaarily propellant, old pieces are discarded ffor getting out of >round 1. Are the factory joints separated at refilling time, so they're filled in 8 or 9 sections instead of 4? 2. After Challenger were the existing sections remachined for the new joints or did they all get dumped? 3. What's with the stiffening rings on the lower sections? 4. How many sections have been discarded and do Thiokol employees get to take them home to use as backyard pools? i seriously doubt any challeger era srb segments are still around. they were all reengineered for better sealing. over the life of the shuttles there must of been lots of flight flown articles discarded "Bob Haller" <hallerb@aol.com> wrote on 16 Apr 2006 15:51:11 -0700 >Right now we can't fly the Lunar CEV SM and CM on one CLV rocket so the new >plan is called "Lunar 2.5". We launch the CEV service module (minus the CEV >capsule) on a CLV 1st. Followed in a day to two by a CEV Command Module and >crew (minus the SM) launched by a second CLV. The CM rendezvous and docks the >with SM. This is totally bizarre! The need to develop a new CLV is also bizarre, when the Delta IV Heavy with a low Earth orbit (LEO) payload to 185 km and 28.5 degree is 25.8 t (1 t = 1000 kg). According to Astronautix the CEV mass is 23.2 t (13.9 t empty, 9.3 t propellant), so a Delta IV Heavy should be sufficient, but that was with LOX/methane propellants. With storable propellants, mass increases to 24.7 t (11.0 t propellant), still within the capability of a Delta IVH. As pointed out in http://www.astronautix.com/craft/cev.htm for every kg you move from the capsule to an orbital module, you reduce overall vehicle mass by 2 kg. General Electric did a study of a Soyuz type configuration for Apollo before Soyuz was known in the West (called Apollo D-2 http://www.astronautix.com/craft/apollod2.htm ). Soyuz has an empty mass of 6.34 t (2.02 t service module, 2.95 t capsule and 1.37 t orbital module) and an internal volume of 8.5 m^3 (cubic metres). CEV has an empty mass of 13.89 t (9.51 t capsule and 4.38 t service module) and 12 m^3 of volume. So, for 2.2 times the mass, CEV has only 1.4 times more volume! Shenzhou has an empty mass of 6.84 t (1.5 t orbital module, 3.24 t capsule and 2.1 t service module) and a volume of 14 m^3 (6 m^3 in the capsule and 8 m^3 in the oribital module). So for a two times mass increase, CEV has 14% less volume! Note that some of that mass increase is due to having a higher delta-V (1823 m/s versus 388 m/s) which results in a larger service module. Surprisingly, the capsule has 2 m^3 per person, the same as Apollo and CEV, while the Soyuz capsule has 1.17 m^3 per person. The Shenzhou capsule diameter is 2.52 m. By increasing this by 2^{1/3} = 1.26 times to 3.18 m, we can fit four astronauts below with two astronauts above. With 7 degree angled sidewalls, this should give a total volume of 12 m^3. The mass should increase by 3.24x2^{2/3} = 5.14 t. Increasing the orbital module diameter from 2.25 to 2.91 m the mass increases by (2.91/2.25)^2x1.5 = 2.51 t and (2.91/2.25)^3x8 = 17.3 m^3, giving a total volume of 29.3 m^3, 2.4 times more than CEV! Even though the capsule volumes are the same, the reason why the Soyuz type capsule is much less than an Apollo type capsule is the more efficient shape and that mass unnecessary for re-entry has been moved into the orbital module. Using an iterative technique, I estimate a service module mass of 4.19 t and propellant mass of 7.95 t with LOX/CH4. This gives a spacecraft mass of 11.84 t and total mass of 19.79 t. With storable propellants, the service module mass is 3.96 t (the smaller mass is due to the smaller propellant volume), propellant mass is 9.38 t, spacecraft mass is 11.61 t and total mass is 20.99 t. The former could be launched by an Atlas 551 which has a 20.05 t payload. Assumptions made are exhaust speeds of 3550 and 3079 m/s and densities of 0.8376 and 1.2051 kg/L for LOX/CH4 and storable (N2O4/MMH) propellants. The SM mass was calculated using m = 2.214*V^0.2835 where V is propellant volume in m^3 and m is in t's (this gives the Shenzhou and CEV values when plugged in). In conclusion (C = LOX/CH4, S = N204/MMH) Shenzhou CEV(C) CEV(S) CEV*(C) CEV*(S) mass capsule (t) 3.24 9.51 9.51 5.14 5.14 mass orbital module (t) 1.50 - - 2.51 2.51 mass service module (t) 2.10 4.38 4.15 4.19 3.96 mass space craft (t) 6.84 13.89 13.66 11.84 11.61 mass propellant (t) 1.00 9.30 11.03 7.95 9.38 mass total (t) 7.84 23.19 24.69 19.79 20.99 volume capsule (m^3} 6.0 12.0 12.0 12.0 12.0 volume service module (m^3) 8.0 - - 17.3 17.3 volume total (m^3) 14.0 12.0 12.0 29.3 29.3 diameter (m) 2.52 5.50 5.50 3.18 3.18 Crew 3 4/6 4/6 4/6 4/6 As is typical with Soyuz/Apollo comparisons, Soyuz gives a smaller mass with a much larger internal volume. SignatureSteven S. Pietrobon, Small World Communications, 6 First Avenue Payneham South SA 5070, Australia fax +61 8 8332 3177 mailto:steven@sworld.com.au http://www.sworld.com.au/ > This is totally bizarre! The need to develop a new CLV is also bizarre, when the > Delta IV Heavy with a low Earth orbit (LEO) payload to 185 km and 28.5 degree is > 25.8 t (1 t = 1000 kg). Nothing bizarre about it: the Delta isn't pork-rated by NASA. Mark > "Bob Haller" <hallerb@aol.com> wrote on 16 Apr 2006 15:51:11 -0700 > [quoted text clipped - 5 lines] > > This is totally bizarre! Indeed it is. That is because the original report appears to be incorrect. The Stick is still planned to be a 5-segment SRB topped by a J-2X powered second stage, according to all of the official news sources, and according to the less official but often correct scuttlebutt, word-of-mouth type sources > The need to develop a new CLV is also bizarre, when the > Delta IV Heavy with a low Earth orbit (LEO) payload to 185 km and 28.5 degree is > 25.8 t (1 t = 1000 kg). These numbers are for a Delta IV Heavy flying a lofted ascent trajectory, which cannot be used for a manned CEV ascent. NASA needs to use an ascent profile with a less aggressive early altitude gain. A Delta IV as-is, with its low-thrust upper stage, would only be able to haul a payload in the low to mid teens of tonnes, maybe, to orbit on such a profile. CEV needs a rocket with a more powerful upper stage to get the job done, regardless of whether the first stage is an SRB or a cluster of three Delta IV CBCs. - Ed Kyle > teens of tonnes, maybe, to orbit on such a profile. CEV > needs a rocket with a more powerful upper stage to get the > job done, regardless of whether the first stage is an SRB or > a cluster of three Delta IV CBCs. If the upper stage thrust is too low, then uprate it with one or more RL60s/MB-60s and some additional propellant. (Likely will need to uprate the RS-68s?) Surely a far cheaper and faster way to get a CEV launch vehicle. The EELVs have plenty of room for improvement without radical redesign. --Damon > If the upper stage thrust is too low, then uprate it with one > or more RL60s/MB-60s and some additional propellant. (Likely > will need to uprate the RS-68s?) Surely a far cheaper and faster > way to get a CEV launch vehicle. The EELVs have plenty of room for > improvement without radical redesign. IMHO the Delta IV Heavy is capable of doing most of NASA's planned missions. Also, don't forget that Boeing did study heavier versions (e.g. 5 modules 1st stage). According to astronautix the AirForce paid $254 Mil. for the 2004 launch. "Hyperboreea" <hyperboreea@yahoo.com> wrote in news:1147137589.151395.16380 @g10g2000cwb.googlegroups.com: >> If the upper stage thrust is too low, then uprate it with one >> or more RL60s/MB-60s and some additional propellant. (Likely [quoted text clipped - 5 lines] > missions. Also, don't forget that Boeing did study heavier versions >>. > (e.g. 5 > modules 1st stage). That would require a new launch facility, and possibly significant changes to the core CBC, but certainly highly feasible. An EELV CLV would probably require a new launch facility anyway, hopefully with a MLP instead of a fixed stand as Delta IV now uses. --Damon > > teens of tonnes, maybe, to orbit on such a profile. CEV > > needs a rocket with a more powerful upper stage to get the [quoted text clipped - 6 lines] > way to get a CEV launch vehicle. The EELVs have plenty of room for > improvement without radical redesign. The upper stage would have to have larger propellant tanks too, to carry more propellant for the higher-thrust burn. To offset this mass, the CBCs would either have to be only partially loaded with propellant (perhaps just the two strap-ons), or the RS-68s would have to be upgraded to provide more liftoff thrust. As to whether the job could be done cheaper with EELVs or the Stick, I don't know. The ESAS study determined that the EELV option would cost more. My gut feeling is that the Stick, which will weigh hundreds of tonnes more than EELV at liftoff, will almost certainly cost more. But someone at NASA decided long ago that NASA wasn't going to depend on Pentagon rockets to launch astronauts, period. And at any rate, the CEV "payload" and its mission are going to cost quite a bit more than the launcher no matter which launcher is used. I always expected that NASA would "end up" with one of the two EELVs while the other would work for the Pentagon. This might still happen, if CLV were to rapidly outrun its projected budget say, but the chances are dim and becoming dimmer each day. I'm now starting to believe that the final result of all of this will be the elimination of one of the EELVs altogether. - Ed Kyle >The upper stage would have to have larger propellant tanks too, >to carry more propellant for the higher-thrust burn. To offset this >mass, the CBCs would either have to be only partially loaded >with propellant (perhaps just the two strap-ons), or the RS-68s >would have to be upgraded to provide more liftoff thrust. How about a "short" CBC derivative, with the two outer CBCs being shorter than the center CBC? Same tooling, same engines, just smaller tanks. This would trade first stage mass for upper stage mass. Brian > >The upper stage would have to have larger propellant tanks too, > >to carry more propellant for the higher-thrust burn. To offset this [quoted text clipped - 5 lines] > shorter than the center CBC? Same tooling, same engines, just smaller > tanks. This would trade first stage mass for upper stage mass. It would be cheaper to simply use the existing CBCs, but only partially fill them with propellant. First stage dry mass is less important than upper stage dry mass, so the extra mass penalty wouldn't be too bad, and would actually be offset by the extra delta-v provided by the upper stage. A Delta 4H set up this way should actually be able to boost more payload to LEO than a standard Delta 4H. - Ed Kyle >> How about a "short" CBC derivative, with the two outer CBCs being >> shorter than the center CBC? Same tooling, same engines, just smaller [quoted text clipped - 7 lines] >should actually be able to boost more payload to LEO than a >standard Delta 4H. True enough, but ISTR you're always pointing out the mass differences between vehicles and saying one is better because it weighs less, etc. (i.e., how much heavier a CLV is versus a D-IVH.) So if we can get the dry mass down, wouldn't that be a good thing? Would the "short tank" derivative also be attractive as the core of a Delta IV-Lite, finally letting Boeing kill Delta II? Brian > >> How about a "short" CBC derivative, with the two outer CBCs being > >> shorter than the center CBC? Same tooling, same engines, just smaller [quoted text clipped - 14 lines] > derivative also be attractive as the core of a Delta IV-Lite, finally > letting Boeing kill Delta II? This is a more or less even mass trade. The second stage grows from 30-ish tonnes to, say, 80-ish tonnes. The 50 tonne difference is balanced by offloading propellant from the strap-on CBCs. The modified rocket weighs the same at liftoff as the original (and still a couple hundred tonnes less than the Stick - leading me to believe that it could end up costing less). The strap-on CBCs would still be loaded at the 87.5% level, so the dry tank mass savings from developing and building a short tank would hardly be worth the bother and expense. As for replacing Delta II, Boeing would probably have to *stretch* the Delta IV CBC to be able to replicate Delta II performance, assuming the same second stage were used. (A standard Delta II second stage on top of a standard CBC would only be able to replicate the performance of a Delta 2-7420, roughly, or about 4+ tonnes to LEO). It might be better to simply build and launch more basic two-stage Delta IV Medium vehicles, which can haul 8.4 tonnes to LEO - about 3.3 tonnes more than a Delta 2-7920. But you would have to build a lot of Delta IVs to narrow the cost gap. Right now, a Delta IV Medium is costing something north of $150 million while a Delta II can cost something less than $90 million. Perhaps the best option is to keep Delta II. It is a cost-effective, steady performer with a proven track record. Why not keep it until it can clearly be beat at its own game by something better (Delta IV Lite apparently not being that something). - Ed Kyle > As to whether the job could be done cheaper with EELVs or > the Stick, I don't know. The ESAS study determined that the > EELV option would cost more. My gut feeling is that the Stick, > which will weigh hundreds of tonnes more than EELV at liftoff, > will almost certainly cost more. A look at the December 2005 Selected Aquisition Report (you can Google it) shows that it will be expensive either way. The average EELV launch is now expected to cost $230 million, 2.4 times as much as the 1995 estimate in 2005 dollars. This means that an EELV Heavy launch is costing almost $300 million now, while the "Medium" vehicles are up to $160 million or so. Now I understand why the EELVs can't compete for commercial launches. Note that these costs would rise for an EELV modified to handle crew launch. My best guess is that an SRB based Crew Launch Vehicle would cost substantially more than $300 million per launch, perhaps as much as $500 million per launch, if the launch rate was only two or so per year, but could cost less than $300 million if the launch rate were higher, say four per year. Current plans only call for two launches per year once ISS support ends. Bottom line is that CLV launch costs would be roughly in the same ballpark regardless of launch vehicle choice. The CEV and mission costs, and fixed ground costs, are going to dominate. These CEV missions, including launch, are probably going to cost something like $0.75 to $1.0 billion each. - Ed Kyle > My best guess is that an SRB based Crew Launch Vehicle > would cost substantially more than $300 million per launch, > perhaps as much as $500 million per launch, So, NASA is spending billions to build a glorified Apollo that will have less functionality than the Shuttle but will end up costing just as much to launch as the shuttle ? Seems to me that spending a few billions to improve the shuttle and build a new one with the improvements would end up costing less than the CEV both for the design/cosnstruction phase and for actual operation. > > My best guess is that an SRB based Crew Launch Vehicle > > would cost substantially more than $300 million per launch, [quoted text clipped - 3 lines] > less functionality than the Shuttle but will end up costing just as much > to launch as the shuttle ? Space shuttle missions cost well more than $1 billion each (the number may be nearer $1.5 billion each by now). Take total program costs, adjusted for inflation, and divide by the number of missions. That is the real number, and it is the number I am using in my CLV discussion. > Seems to me that spending a few billions to improve the shuttle and > build a new one with the improvements would end up costing less than the > CEV both for the design/cosnstruction phase and for actual operation. Shuttle is finished, or should be. It died the day that Columbia fluttered down in tiny pieces across Texas and Louisiana. - Ed Kyle yeah at 1.5 billion per flight, its fiancially obsolete and highly risky too. no launch boost escape, too many ways to get dead.... theres no way nasa will ever launch a meaningful number of flights to finish the station by 2010. better to pay the international partners for their costs..... > > As to whether the job could be done cheaper with EELVs or > > the Stick, I don't know. The ESAS study determined that the [quoted text clipped - 21 lines] > Current plans only call for two launches per year once ISS > support ends. Assume a plausible figure of $80 million marginal cost for a CEV, and fixed costs for the launcher of $1 billion a year, that sounds about right. However: CLV will share much of its post ISS overhead with the CaLV, using the same SRBs, J2 engines, VAB and launch facilities, If, say 2/3 of the fixed cost is allocated to the CaLV, the cost at two CLV launches a year becomes much more resonable. Will McLean >> > teens of tonnes, maybe, to orbit on such a profile. CEV >> > needs a rocket with a more powerful upper stage to get the [quoted text clipped - 12 lines] > with propellant (perhaps just the two strap-ons), or the RS-68s > would have to be upgraded to provide more liftoff thrust. I would disagree. The current Delta IV second stage is already stretched. Traditionally the second stage for LEO rockets only goes for about 250 seconds. A dual RL-10 would have about 550 seconds. A single RL/MB-60 about 500 seconds. Even quad RL-10 or dual RL/MB-60 would have more then 250 seconds of fuel with the existing stage. Only a quad RL/MB-60 or J2-S/X would need a much larger second stage. Even the Atlas 5 with dual RL-10s is much longer burning then most second stage engines. > >> > teens of tonnes, maybe, to orbit on such a profile. CEV > >> > needs a rocket with a more powerful upper stage to get the [quoted text clipped - 26 lines] > Even the Atlas 5 with dual RL-10s is much longer burning then most > second stage engines. Saturn IB's S-IVB second stage, with an Apollo payload, had a startup thrust to weight ratio of something like 0.78, and burned for something like 450 seconds. To have the same thrust to weight ratio, needed to fly NASA's non-lofted ascent, a Delta IV-Heavy second stage would need to use four RL10s, adding a tonne of dry mass to the stage. The resulting vehicle would lose about one tonne of lifting capability to LEO and would not be able to haul a CEV. On the other hand, if the upper stage were stretched and loaded with 50 tonnes more propellant (offloaded from the strap-on CBCs) and powered appropriately, it would be able to boost five tonnes more than a standard Delta IV Heavy and would probably be able to handle a CEV. This despite the fact that the modified rocket would weigh the same as a standard Delta IV Heavy at liftoff! This is why the CLV upper stage is sized the way that it is. A LEO rocket is more efficient when the second stage takes on a bigger share of the Delta-V effort. - Ed Kyle |
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