Author Topic: RS-25E  (Read 54287 times)

Offline Ronsmytheiii

  • Moderator
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 23394
  • Liked: 1879
  • Likes Given: 1023
Re: RS-25E
« Reply #40 on: 03/26/2012 02:14 am »
As for RS-25E on SLS versus RS-68, remember a few things:

  1.  Ares V with RS-68 necessitated an increase in core diameter, dramatically increasing the overall costs of the core. 

2.  Eventually it required a sixth engine on the core due to the performance of the rS-68.

3. Ultimately Constrllation was working a switch back to the SSME versus RS-68

RS-25E always has a backup configuration in the D model, which in large block buys will decrease per unit costs.  Any changes for E will have little performance gains but will focus on lowering costs. Any changes to the RS-68 to work for SLS in the thermal environment of the RSMV will dramatically increase its cost, so better for ULA/USAF ect to leave it be.  Besides, j-2x has used RS-68 components, and it has been stated the -25E will as well.

Offline edkyle99

  • Expert
  • Senior Member
  • *****
  • Posts: 15391
    • Space Launch Report
  • Liked: 8565
  • Likes Given: 1356
Re: RS-25E
« Reply #41 on: 03/26/2012 04:40 am »
As for RS-25E on SLS versus RS-68, remember a few things:

  1.  Ares V with RS-68 necessitated an increase in core diameter, dramatically increasing the overall costs of the core. 

2.  Eventually it required a sixth engine on the core due to the performance of the rS-68.

3. Ultimately Constrllation was working a switch back to the SSME versus RS-68

True, but this was for Ares V, not SLS.  SLS does not have to meet the payload requirements that drove Ares V to the fatter tank, etc. - especially Block 1.  It is not immediately clear to me that an RS-68 SLS would have to have a 10 meter core, though that might be the case.

 - Ed Kyle

Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: RS-25E
« Reply #42 on: 03/26/2012 04:24 pm »
As for RS-25E on SLS versus RS-68, remember a few things:

  1.  Ares V with RS-68 necessitated an increase in core diameter, dramatically increasing the overall costs of the core. 

2.  Eventually it required a sixth engine on the core due to the performance of the rS-68.

3. Ultimately Constrllation was working a switch back to the SSME versus RS-68

RS-25E always has a backup configuration in the D model, which in large block buys will decrease per unit costs.  Any changes for E will have little performance gains but will focus on lowering costs. Any changes to the RS-68 to work for SLS in the thermal environment of the RSMV will dramatically increase its cost, so better for ULA/USAF ect to leave it be.  Besides, j-2x has used RS-68 components, and it has been stated the -25E will as well.

As I understood it, the reason CxP went back to RS-25 from RS-68, the reason Direct went back to RS-25 from RS-68, and the reason SLS went right to RS-25, was because it was discovered the ablatively cooled RS-68 couldn't withstand the heating environment next to the SRB's.  Perhaps they could with Rp-1 LRB boosters, I don't know.   
That it didn't have much to do with performance. 
Sticking with RS-68 would have meant a regeneratively cooled version would need to have been created (I think it was referred to as RS-68R), and that would ahve cost a lot more money and negated the advantage of RS-68, whcih was it was an existing off-the-shelf engine, and it was (or could be ) relatively cheap. 
So the RS-25 was the only hydrolox, regen cooled, off-the-shelf engine and they went back to it.

So, unless I understand that incorrectly, RS-68's are out of the question for SLS if SRB's are in the picture.  I understood the USAF wasn't all that keep on a regen cooled RS-68, because that would increase the costs of their D4 launches.  Regen RS-68 obviously would cost more than ablative RS-68.  BE interesting to know if RS-68's could withstand the the heating environment of RP-1 boosters.  Could be an argument for LRB's for Block 1A. An option to go to cheaper RS-68's, although it'd mean a new MPS structure, and that might not be desirable.  They'd have to be man-rated too.  And for the same reason I understood USAF didn't want it regen cooled or man-rated, because it would increase their costs for their LV's that didn't need them to be either.   
I believe that's part of the reason ULA when the man-rated route with Atlas instead of Delta.
Despite there not being an AVH, AV and the RD-180 was cheaper and easier to man-rate than D4 and the RS-68 (The Ruskies designed it to be man-rated as I understand, just that US man-rating regulations are a little more than the Ruskies.  But it is still pretty close already) and there's not commercial crew that look to need the AVH anyway.

So a cheaper version of RS-25D, the RS-25E, was chosen as the engine of record for CxP, Direct, and then SLS.   

That was my understanding anyway.  I might be wrong, as always.

Offline hydra9

  • Full Member
  • ***
  • Posts: 349
  • Liked: 16
  • Likes Given: 6
Re: RS-25E
« Reply #43 on: 03/29/2012 10:36 pm »
Ironically, the 5-segment SRBs are still not enough to achieve the mandated ultimate goal of being able to lift at least 130 metric tons into orbit-- unless four of the heavy solid rocket boosters are utilized. And as previous posters have noted, this would be an extremely heavy vehicle to transport to the launching pad.

But there is a possible scenario that could actually reintroduce the current RS-68 engines back into the mix. The current SSME are limited to only 15 engines and it looks like the RS-25E won't be ready for production until at least 2021. If NASA decided to limit the use of the SSME only to man-rated test and manned flights, only 3 engines would be required with SRBs with the possibility of up to 5 missions (one or two unmanned test missions and three or four manned missions).

But that would mean that there would be no engines available to test cargo missions until 2021. However, RS-68 engines could be utilized for unmanned heavy lift cargo missions without SRBs by simply using three SLS core stages in a Delta-IV heavy configuration. Boeing  originally proposed such a vehicle, utilizing 8 meter in diameter core stages, each propelled by 4 RS-68 engines. With an upper stage, such a vehicle was argued to able to lift more than 146 tonnes into orbit.

The SLS core stage will have an 8.4 meter diameter. So with an upper stage, such a vehicle should exceed the lifting capability of the Delta Super Heavy concept.

This would mean that no new side-mounted boosters would have to be developed and no new engines. It could also mean that SLS super heavy cargo boosters could be tested as early as 2017 instead of waiting until perhaps the mid 2020s for a new solid or liquid booster to be ready to be utilized.

Marcel F. Williams


 

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37440
  • Cape Canaveral Spaceport
  • Liked: 21450
  • Likes Given: 428
Re: RS-25E
« Reply #44 on: 03/30/2012 02:18 am »
Ironically, the 5-segment SRBs are still not enough to achieve the mandated ultimate goal of being able to lift at least 130 metric tons into orbit-- unless four of the heavy solid rocket boosters are utilized.

Not true

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37440
  • Cape Canaveral Spaceport
  • Liked: 21450
  • Likes Given: 428
Re: RS-25E
« Reply #45 on: 03/30/2012 02:22 am »
simply using three SLS core stages in a Delta-IV heavy configuration.
 

That is nonsense.   The forward SRB attach fittings and the lack of aft support structure means the SLS cores can not be used in that fashion without a complete redesign.

Offline hydra9

  • Full Member
  • ***
  • Posts: 349
  • Liked: 16
  • Likes Given: 6
Re: RS-25E
« Reply #46 on: 03/30/2012 08:50 am »
Ironically, the 5-segment SRBs are still not enough to achieve the mandated ultimate goal of being able to lift at least 130 metric tons into orbit-- unless four of the heavy solid rocket boosters are utilized.

Not true

Please elaborate!


Offline hydra9

  • Full Member
  • ***
  • Posts: 349
  • Liked: 16
  • Likes Given: 6
Re: RS-25E
« Reply #47 on: 03/30/2012 09:18 am »
simply using three SLS core stages in a Delta-IV heavy configuration.
 

That is nonsense.   The forward SRB attach fittings and the lack of aft support structure means the SLS cores can not be used in that fashion without a complete redesign.


The first SLS core stage is some five years away from its first launch configuration which still gives NASA time to develop a core stage that can be flexibly used with or wthout SRBs or side-mounted rockets. I agree that some modifications are likely to be required for a three core vehicle. But complete redesign would mean changing the fuel tank diameters or dramatically stretching the height of fuel tanks which would seem unlikely. And Boeing has already proposed utilizing an 8.4 meter in diameter SLS like core vehicle without SRBs or other side-mounted rockets.

Marcel F. Williams

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37440
  • Cape Canaveral Spaceport
  • Liked: 21450
  • Likes Given: 428
Re: RS-25E
« Reply #48 on: 03/30/2012 11:15 am »

The first SLS core stage is some five years away from its first launch configuration which still gives NASA time to develop a core stage that can be flexibly used with or wthout SRBs or side-mounted rockets

No, it won't be "flexible" because it will be too heavy to do either role properly.  It won't meet performance targets.  It has to be one or the other.

The point is moot, NASA isn't going to build a core that can stand alone.  Any further discussion of this is ridiculous.

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37440
  • Cape Canaveral Spaceport
  • Liked: 21450
  • Likes Given: 428
Re: RS-25E
« Reply #49 on: 03/30/2012 11:17 am »
Ironically, the 5-segment SRBs are still not enough to achieve the mandated ultimate goal of being able to lift at least 130 metric tons into orbit-- unless four of the heavy solid rocket boosters are utilized.

Not true

Please elaborate!


The onus is on you to show that 4 SRB's are required when studies show that it isn't.

Offline muomega0

  • Full Member
  • ****
  • Posts: 862
  • Liked: 70
  • Likes Given: 1
Re: RS-25E
« Reply #50 on: 03/30/2012 01:06 pm »
Quick, and probably stupid, question from a non-rocket scientist: if the RS-25E actually approaches the cost of the RS-68, could it replace the RS-68 as our all-purpose H2 engine? It seems like it would be a good idea to, as the saying goes, put all our wood behind one arrow.

You would need about 1.5 to 1.6 RS-25 engines to replace each RS-68 - which from a practical standpoint of course means that you would need two RS-25 engines for each Delta IV core.  The cost comparison would have to take that into account, along with the significant cost of re-engineering Delta IV to handle the new propulsion.

 - Ed Kyle 

Yea, this really begs a few questions.

Within a couple years, assuming F9, FH, and Antaries get flying ok, does ULA need two redundant launchers in A5 and D4?  Those two LV’s were born of the DoD wanting backup LV’s so they wouldn’t be hosed if one was grounded for some reason like they were with STS after Challenger.  Two companies, two LV’s.  But now that they are merged, and there’s other similar class LV’s about to come on line, I’m not sure the need for ULA to maintain two separate LV’s that do essentially the same thing. 
I think the advantage of D4, is if the launch rate was high enough, it’s costs could be very cheap.  But ULA will never get that splitting their work between two launchers.  Especially if SpaceX and Orbital cut into their DoD work at all.
A5 has better growth potential into larger capacity LV’s visa vi A5P2.  So what does ULA do going forward?  Eliminate one or the other?  If so, which one? Personally, I don’t think having hydrolox as a first stage is a good way to go, so I’d probably look at eliminating D4 all together, and using that tooling to make A5P2 to replace D4H.  So ULA has two CCB’s, but common engines, probably common avionics, and if they developed ACES, common upper stages.  LC-37B could be modified, fairly easily I would think, to take a 5m kerolox core instead of the 5m hydrolox D4 core.  And it should even be able to handle a future A5P2-Heavy, which would have the same footprint as the current D4H (although much greater thrust).  LC-41 would continue to launch A5’s as normal for the normal EELV-class payloads.
Centralize around the A5 platform, fold up the D4 platform, and try to get those flight rates up and costs down. 
Which would mean eliminating the need for the RS68 completely. 

Going the other way and eliminating the A5, then you could look at centralizing around the single 5m hydrolox core, with RS25E engines.    Each core would need two RS25’s throttling, so the ultimate price per core would go up, but perhaps the price of the RS25E’s could come down enough with the shared SLS and D4 volume to be similar to current RS68 prices.  The economics of scale at work, especially if they can trim down the RS25E enough since it doesn’t need to be reused anymore.  A D4H could have two RS25E’s on each booster CCB, and then one on the central core.  Your total thrust should be about the same as three RS68’s, but the core should be able to put the payload directly into LEO without the need for a 2nd stage burn.  Or at least just a brief one as will be the case with SLS 1 and 1A.  That should gain you some BLEO performance on the D4H.  (But I’m not expert, so this is just gut feeling).
However, I think Downix or someone said at one point that even if PWR is making both the RS68 and RS25E, though they are not the same engine, they do share a lot of the same infrastructure, so increasing use of one brings the cost of both down.  The same facilities, personnel, and equipment and such would be used for both, as well as J2X.  Even though that’d be 3 engines, the economies of scale are shared.  Again, I just remember that being said, no sure if it’s true.  But if it is, Then ULA could just stick with RS68’s on their D4 LV’s (and save redesign costs), and those prices will come down due to all ULA launches being on D4, so twice as many RS68’s being produced and not split between two LV’s, and with the RS25E’s being produced for SLS.  As well as J2X eventually…maybe…


So for SLS and RS25es
    - SRMs can meet the metric tonne requirements
    - incorporating solids drastically increase crew LAS mass
      (not common to multiple LVs )
    - new liquid boosters still *requires* RS25s (regen)-base heating
    - 8-10 launches per year provides 1000 mT significantly exceeds need
    - economics of 4-6 launches per year significantly favors smaller LVs
    - RS-68R not worth the dollars (?) not common with other configs
    - P&W are modernizing plant to reduce costs
    - still loses economically to a smaller LV to service ISS
    - Studies indicate US should launch crew at least two vehicles
    - US and world has excess launch capacity
    - J2X  - has no commonality with any other element
    - the whole exercise is comes across as trying to fit square pegs...
    - SLS its just not viable economically

So since this is the RS-25 E thread, your discussion above on the go-forward plan without SLS ( Atlas Delta Falcon Russia  etc) is spot on and should be discussed on an existing thread or new one.  Suggestions?
But to continue the discuss with SLS is counterproductive.

Actually, the time spent on SLS hardware may actually be providing the advantage of other COTS LVs vs  Human Rating Atlas and Delta

Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: RS-25E
« Reply #51 on: 03/31/2012 12:07 am »
Quick, and probably stupid, question from a non-rocket scientist: if the RS-25E actually approaches the cost of the RS-68, could it replace the RS-68 as our all-purpose H2 engine? It seems like it would be a good idea to, as the saying goes, put all our wood behind one arrow.

You would need about 1.5 to 1.6 RS-25 engines to replace each RS-68 - which from a practical standpoint of course means that you would need two RS-25 engines for each Delta IV core.  The cost comparison would have to take that into account, along with the significant cost of re-engineering Delta IV to handle the new propulsion.

 - Ed Kyle 

Yea, this really begs a few questions.

Within a couple years, assuming F9, FH, and Antaries get flying ok, does ULA need two redundant launchers in A5 and D4?  Those two LV’s were born of the DoD wanting backup LV’s so they wouldn’t be hosed if one was grounded for some reason like they were with STS after Challenger.  Two companies, two LV’s.  But now that they are merged, and there’s other similar class LV’s about to come on line, I’m not sure the need for ULA to maintain two separate LV’s that do essentially the same thing. 
I think the advantage of D4, is if the launch rate was high enough, it’s costs could be very cheap.  But ULA will never get that splitting their work between two launchers.  Especially if SpaceX and Orbital cut into their DoD work at all.
A5 has better growth potential into larger capacity LV’s visa vi A5P2.  So what does ULA do going forward?  Eliminate one or the other?  If so, which one? Personally, I don’t think having hydrolox as a first stage is a good way to go, so I’d probably look at eliminating D4 all together, and using that tooling to make A5P2 to replace D4H.  So ULA has two CCB’s, but common engines, probably common avionics, and if they developed ACES, common upper stages.  LC-37B could be modified, fairly easily I would think, to take a 5m kerolox core instead of the 5m hydrolox D4 core.  And it should even be able to handle a future A5P2-Heavy, which would have the same footprint as the current D4H (although much greater thrust).  LC-41 would continue to launch A5’s as normal for the normal EELV-class payloads.
Centralize around the A5 platform, fold up the D4 platform, and try to get those flight rates up and costs down. 
Which would mean eliminating the need for the RS68 completely. 

Going the other way and eliminating the A5, then you could look at centralizing around the single 5m hydrolox core, with RS25E engines.    Each core would need two RS25’s throttling, so the ultimate price per core would go up, but perhaps the price of the RS25E’s could come down enough with the shared SLS and D4 volume to be similar to current RS68 prices.  The economics of scale at work, especially if they can trim down the RS25E enough since it doesn’t need to be reused anymore.  A D4H could have two RS25E’s on each booster CCB, and then one on the central core.  Your total thrust should be about the same as three RS68’s, but the core should be able to put the payload directly into LEO without the need for a 2nd stage burn.  Or at least just a brief one as will be the case with SLS 1 and 1A.  That should gain you some BLEO performance on the D4H.  (But I’m not expert, so this is just gut feeling).
However, I think Downix or someone said at one point that even if PWR is making both the RS68 and RS25E, though they are not the same engine, they do share a lot of the same infrastructure, so increasing use of one brings the cost of both down.  The same facilities, personnel, and equipment and such would be used for both, as well as J2X.  Even though that’d be 3 engines, the economies of scale are shared.  Again, I just remember that being said, no sure if it’s true.  But if it is, Then ULA could just stick with RS68’s on their D4 LV’s (and save redesign costs), and those prices will come down due to all ULA launches being on D4, so twice as many RS68’s being produced and not split between two LV’s, and with the RS25E’s being produced for SLS.  As well as J2X eventually…maybe…


So for SLS and RS25es
    - SRMs can meet the metric tonne requirements
    - incorporating solids drastically increase crew LAS mass
      (not common to multiple LVs )
    - new liquid boosters still *requires* RS25s (regen)-base heating
    - 8-10 launches per year provides 1000 mT significantly exceeds need
    - economics of 4-6 launches per year significantly favors smaller LVs
    - RS-68R not worth the dollars (?) not common with other configs
    - P&W are modernizing plant to reduce costs
    - still loses economically to a smaller LV to service ISS
    - Studies indicate US should launch crew at least two vehicles
    - US and world has excess launch capacity
    - J2X  - has no commonality with any other element
    - the whole exercise is comes across as trying to fit square pegs...
    - SLS its just not viable economically

So since this is the RS-25 E thread, your discussion above on the go-forward plan without SLS ( Atlas Delta Falcon Russia  etc) is spot on and should be discussed on an existing thread or new one.  Suggestions?
But to continue the discuss with SLS is counterproductive.

Actually, the time spent on SLS hardware may actually be providing the advantage of other COTS LVs vs  Human Rating Atlas and Delta

Well, this post of mine was from a month ago, and mainly looking at ULA retiring one of their two LV’s, because the main reason for two LV’s was for redundancy for DoD.  Something that will be achieved in the near future with Antaries and Falcon9.  ULA could save money by focusing on one or the other, and maybe using RS25E for D4 if they choose it.

But in the mean time, Jim has pretty much straightened me out by informing me that DoD is less concerned about launch costs, and more concerned about reliability, which AV and D4 both have.  Also, that it doesn’t appear that LM or Boeing want to give up “their” LV for the other one.  That’s why Boeing was proposing the DCSS or modified DCSS for the Gateway proposal, rather than ACES.  They want that contract and don’t want to share anything with LM, which they can since ULA only governs EELV launches for the government. 

So, it doesn’t appear that Boeing or LM is at all interested in getting rid of their LV’s, and it appears that DoD isn’t interested in risking their payloads on these new upstart LV’s any time soon.   So that pretty much negates my whole genius plan of ULA streamlining their capabilities to compete with the upstarts.  If they are guaranteed the government launches, they don’t have to compete.  Typical of government contracts, and why government contractors are so friggin expensive.
ULA would only be interested in using D4 tooling for A5P2, if there’s government payloads that’d want it under the EELV program.  So, if I understand, if NASA had opted to go the EELV path instead of SDHLV path, it’s possible ULA could have then developed AVP2, and AVP2-heavy, for NASA service work, as that’s government. 

(Jim, is this summary more or less correct?  That’s how I understood what you were saying anyway).

Still, if the RAC teams had evaluated either A5P2-Heavy, A5P3a, or perhaps some hybrid HLV that used a D4 core with A5P2 boosters, rather than those screwy configs they did, and given them a fair shake, they might have looked pretty attractive vs. SDHLV.  You could have had a 5m D4 core (with RS25E if RS68 couldn’t handle the heating environment), with theoretically up to six 5m A5P2 booster CCB’s around it.  That would have certainly given you 130+ mt of capacity if NASA ever actually had needed it (which they probably wouldn’t until a Mars program).  But it still could be launched as a single core AVP2 (great for Orion to LEO).  Two AVP2 CCB’s with D4 core, or 3, or 4, or 6 AVP2 CCB’s. 
J2X is not needed.  RL-10’s would work good for a upper stage on smaller configs (ACES perhaps), and NGE or RL-60’s would work for your larger configurations. 

But I digress.  My older post is pretty much toast given what Jim has said.  ULA will continue to operate both LV’s going forward with no plans to retire either to streamline the EELV program, because the principles don’t want to give up “their” rockets.

Offline sdsds

  • Senior Member
  • *****
  • Posts: 7201
  • “With peace and hope for all mankind.”
  • Seattle
  • Liked: 2050
  • Likes Given: 1962
Re: RS-25E
« Reply #52 on: 05/10/2014 10:33 pm »
Quote
NASA anticipates a re-start of the
production line for the RS-25 engine that it plans to use to power the
Block IA/B and Block II vehicles [...] but it has not yet finalized acquisition plans to
manufacture them. According to agency officials, re-starting the
production line would entail at least 3 years, whereas development of
a new engine would require a minimum of 8 years.
http://www.gao.gov/assets/670/663071.pdf

Is GAO talking about RS-25E or something else entirely when they say, "development of a new engine?"
— 𝐬𝐝𝐒𝐝𝐬 —

Offline edkyle99

  • Expert
  • Senior Member
  • *****
  • Posts: 15391
    • Space Launch Report
  • Liked: 8565
  • Likes Given: 1356
Re: RS-25E
« Reply #53 on: 05/11/2014 03:52 am »
Quote
NASA anticipates a re-start of the
production line for the RS-25 engine that it plans to use to power the
Block IA/B and Block II vehicles [...] but it has not yet finalized acquisition plans to
manufacture them. According to agency officials, re-starting the
production line would entail at least 3 years, whereas development of
a new engine would require a minimum of 8 years.
http://www.gao.gov/assets/670/663071.pdf

Is GAO talking about RS-25E or something else entirely when they say, "development of a new engine?"
I think GAO is talking about RS-25E, which would in many ways be a new engine.  RS-25E would be a substantial modification of the existing engine meant to theoretically cut costs.  NASA has the option of simply restarting production of the existing RS-25D engine, which would avoid the cost and time of an 8-year development effort.

 - Ed Kyle
« Last Edit: 05/11/2014 03:53 am by edkyle99 »

Offline Lars_J

  • Senior Member
  • *****
  • Posts: 6160
  • California
  • Liked: 677
  • Likes Given: 195
Re: RS-25E
« Reply #54 on: 05/12/2014 06:00 pm »
A "minimum of 8 years" for RS-25E? Crazy. They might as well close up shop and leave, if it will take that long.

Offline sdsds

  • Senior Member
  • *****
  • Posts: 7201
  • “With peace and hope for all mankind.”
  • Seattle
  • Liked: 2050
  • Likes Given: 1962
Re: RS-25E
« Reply #55 on: 05/12/2014 08:11 pm »
A "minimum of 8 years" for RS-25E? Crazy.

Agreed. Yet RS-25 is a complex design, and we have historical data on how long it has taken to upgrade its main combustion chamber. I think the first SSME with a Large Throat Main Combustion Chamber (i.e. Block IIA) flew on Endeavour during STS-89 in January 1998. Prototyping of that combustion chamber began in 1988. (See "Wings in Orbit", page 163.) 10 years. Ouch.
— 𝐬𝐝𝐒𝐝𝐬 —

Offline bilbo

  • Member
  • Posts: 94
  • Ground control to Major tom...
  • Liked: 27
  • Likes Given: 51
Re: RS-25E
« Reply #56 on: 05/12/2014 11:15 pm »
Ironically, the 5-segment SRBs are still not enough to achieve the mandated ultimate goal of being able to lift at least 130 metric tons into orbit-- unless four of the heavy solid rocket boosters are utilized. And as previous posters have noted, this would be an extremely heavy vehicle to transport to the launching pad.

But there is a possible scenario that could actually reintroduce the current RS-68 engines back into the mix. The current SSME are limited to only 15 engines and it looks like the RS-25E won't be ready for production until at least 2021. If NASA decided to limit the use of the SSME only to man-rated test and manned flights, only 3 engines would be required with SRBs with the possibility of up to 5 missions (one or two unmanned test missions and three or four manned missions).

But that would mean that there would be no engines available to test cargo missions until 2021. However, RS-68 engines could be utilized for unmanned heavy lift cargo missions without SRBs by simply using three SLS core stages in a Delta-IV heavy configuration. Boeing  originally proposed such a vehicle, utilizing 8 meter in diameter core stages, each propelled by 4 RS-68 engines. With an upper stage, such a vehicle was argued to able to lift more than 146 tonnes into orbit.

The SLS core stage will have an 8.4 meter diameter. So with an upper stage, such a vehicle should exceed the lifting capability of the Delta Super Heavy concept.

This would mean that no new side-mounted boosters would have to be developed and no new engines. It could also mean that SLS super heavy cargo boosters could be tested as early as 2017 instead of waiting until perhaps the mid 2020s for a new solid or liquid booster to be ready to be utilized.

Marcel F. Williams
Keep in mind ,  A new President elect is coming in 2016. Advanced boosters could be ready by 2020-2022, if they made insane progress.

Offline Lars_J

  • Senior Member
  • *****
  • Posts: 6160
  • California
  • Liked: 677
  • Likes Given: 195
Re: RS-25E
« Reply #57 on: 05/13/2014 12:06 am »
Keep in mind ,  A new President elect is coming in 2016. Advanced boosters could be ready by 2020-2022, if they made insane progress.
... yep, and if only someone from the other party was president, we would all get ponies.

Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: RS-25E
« Reply #58 on: 05/13/2014 07:11 pm »
Keep in mind ,  A new President elect is coming in 2016. Advanced boosters could be ready by 2020-2022, if they made insane progress.
... yep, and if only someone from the other party was president, we would all get ponies.

I don't think Bilbo mentioned the "other party", just that there would be a new President Elect in 2016.  Which there will be until there's a Constitutional Ammendment in the next 2 years repealing the 22nd Ammendment.

But we can only hope it's someone from the other party...because ponies are awesome.

Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: RS-25E
« Reply #59 on: 05/13/2014 07:29 pm »
Ironically, the 5-segment SRBs are still not enough to achieve the mandated ultimate goal of being able to lift at least 130 metric tons into orbit-- unless four of the heavy solid rocket boosters are utilized. And as previous posters have noted, this would be an extremely heavy vehicle to transport to the launching pad.

But there is a possible scenario that could actually reintroduce the current RS-68 engines back into the mix. The current SSME are limited to only 15 engines and it looks like the RS-25E won't be ready for production until at least 2021. If NASA decided to limit the use of the SSME only to man-rated test and manned flights, only 3 engines would be required with SRBs with the possibility of up to 5 missions (one or two unmanned test missions and three or four manned missions).

But that would mean that there would be no engines available to test cargo missions until 2021. However, RS-68 engines could be utilized for unmanned heavy lift cargo missions without SRBs by simply using three SLS core stages in a Delta-IV heavy configuration. Boeing  originally proposed such a vehicle, utilizing 8 meter in diameter core stages, each propelled by 4 RS-68 engines. With an upper stage, such a vehicle was argued to able to lift more than 146 tonnes into orbit.

The SLS core stage will have an 8.4 meter diameter. So with an upper stage, such a vehicle should exceed the lifting capability of the Delta Super Heavy concept.

This would mean that no new side-mounted boosters would have to be developed and no new engines. It could also mean that SLS super heavy cargo boosters could be tested as early as 2017 instead of waiting until perhaps the mid 2020s for a new solid or liquid booster to be ready to be utilized.

Marcel F. Williams
Keep in mind ,  A new President elect is coming in 2016. Advanced boosters could be ready by 2020-2022, if they made insane progress.

Hydra 9's comments from two years ago are unfeasible, as three 8.4m cores with RS-68's couldn't fit out the VAB doors or over the flame trench.  6.5m CCB's are about the max that could be handled by KSC.  You could get two, maybe 3 RS-68's on 6.5m cores.  Three 6.5m cores with three RS-68's each probably wouldn't get over 130mt. Maybe around 100mt.
Ironically, a 6.5m CCB core with two F-1B's on it, like the Dynetics booster proposal, just a little fatter, along with a new properly sized upper stage/EDS, launching in a 2.5 stage configuration with crossfeed, would have probably gotten the 130mt to LEO NAA2010 was asking for. 

Be interesting to see if any Presidential candidate from either party would push to fast track Advanced boosters, or anything else related to SLS.  NASA doesn't seem like much of a concern for the top politicos from either party right now, unfortuantely.  It doesn't get the ink from the media the way other hot-button wedge issues do.  If it did, we'd probably see more top politicos talking about it.  I think the best we can hope for from the next Administration is that they appoint a NASA Administrator with some real drive and ambition, but still with a pragmatic and practical mind.  Griffin had ambition and got things done, just wasn't very practical about the realistic budget situation and the things he got done turned out to then collapse making things much worse.  Bolden is anything but ambitious about NASA HSF, and drags his feet as much as possible to prefent things from getting done, and thus making them worse.
We need a charasmatic Administrator with drive -and- practicality, who can go and communicate effectively with Congress and the President, and work to get the most bang for the buck, as there likely won't be many more bucks than there are now.  Otherwise NASA's troubles will likely continue.

 

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
1