Author Topic: Alternative HLV Concepts  (Read 76074 times)

Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: Pyrios Alternative HLV Concept
« Reply #20 on: 10/05/2013 12:15 am »
Ed, why do none of your concepts incorporate a common bulkhead for the stage tanks? These F1 based concepts would not be using shuttle tanks (no need for SRB support beam), and the upper stages would be new anyway?

Is common bulkhead such an advanced concept, even though it was used as far back as Saturn V?


I'd be curious about that too.

As a note, after a quick scan of the ESAS concepts, the only ones that used common bulkhead were the first stage of the Atlas Phase 2 concepts.

I think common bulkhead is more exensive than two bulkheads, especailly for LH2/LOX where there's a a large temp differential to insulate against.
On the other hand, LOX/LCH4 would lend itself pretty good to common bulkhead because the temperatures of both aren't too far apart.

Offline edkyle99

  • Expert
  • Senior Member
  • *****
  • Posts: 15391
    • Space Launch Report
  • Liked: 8565
  • Likes Given: 1356
Re: Pyrios Alternative HLV Concept
« Reply #21 on: 10/05/2013 04:17 am »
Ed, why do none of your concepts incorporate a common bulkhead for the stage tanks? These F1 based concepts would not be using shuttle tanks (no need for SRB support beam), and the upper stages would be new anyway?

Is common bulkhead such an advanced concept, even though it was used as far back as Saturn V?
I'm showing separate bulkheads in order to get the worst-case height.  In addition, it is common practice for modern launch vehicle stages to use separate bulkheads for LH2/LOX, to simplify development and reduce costs.  There's a big temperature difference between those two tanks, which has in the past resulted in stress cracking in under-engineering bulkheads.  Internal or inter-bulkhead insulation  is also required, which adds complexity and cost.  Look back at S-IV, S-II, S-IVB, etc. 

What about Centaur, someone is going to ask.  The Centaur tank is not strictly modern, since it was originally developed during the early 1960s, when NASA was trying to squeeze ounces out of the machine.  Its development was also a mess, BTW.

The weight penalty isn't as big as it once was now that composite intertanks have come into play.  As for RP/LOX, no stage of the HLLV diameter category has ever used common bulkheads to my knowledge.  That doesn't mean it is impossible, only that it presents development risk.  The Saturn V S-II stage had common bulkheads, perhaps the largest ever developed, but that stage was a development nightmare that almost cost the program.  North American destroyed two S-II stages in ground test accidents.  S-II is still an amazing piece of engineering, with its Centaur-like propellant mass fraction, but it came at great cost during a time when cost was no object, when development teams worked 24/7. 

 - Ed Kyle
« Last Edit: 10/05/2013 04:24 am by edkyle99 »

Offline edkyle99

  • Expert
  • Senior Member
  • *****
  • Posts: 15391
    • Space Launch Report
  • Liked: 8565
  • Likes Given: 1356
Re: Pyrios Alternative HLV Concept
« Reply #22 on: 10/06/2013 10:26 pm »
Here are a couple of the core-only concepts I like.  These use only two engine types and no strap on boosters.

 - Ed Kyle
« Last Edit: 10/10/2013 06:28 pm by edkyle99 »

Offline Lars_J

  • Senior Member
  • *****
  • Posts: 6160
  • California
  • Liked: 677
  • Likes Given: 195
Re: Pyrios Alternative HLV Concept
« Reply #23 on: 10/07/2013 01:20 am »

Here are a couple of the core-only concepts I like.  These use only two engine types and no strap on boosters.

 - Ed Kyle

Neat, but clustering so many RS-68's so close to each other might require a regeneratively cooled version of the RS-68. And isn't the RS-68 very dependent on a lot of ground equipment to start?

Offline butters

  • Senior Member
  • *****
  • Posts: 2399
  • Liked: 1692
  • Likes Given: 597
Re: Pyrios Alternative HLV Concept
« Reply #24 on: 10/07/2013 01:40 am »
I think the problem with scrapping the SLS core and going with F-1A core(s) is that you inevitably have to replace it with a second stage that needs 3-5 J-2X. So we're back to a Saturn-like family except perhaps with multi-core configurations.

We have these two hydrolox gas-generators. One is smaller than we'd prefer for a super-heavy rocket, and the other has rather disappointing specific impulse. It's enough for me to conclude: screw it, let's stick with the RS-25. Nobody else is going to use this stage anyway.

Offline a_langwich

  • Full Member
  • ****
  • Posts: 735
  • Liked: 212
  • Likes Given: 48
Re: Pyrios Alternative HLV Concept
« Reply #25 on: 10/07/2013 02:12 am »
As for RP/LOX, no stage of the HLLV diameter category has ever used common bulkheads to my knowledge.   

Maybe not HLLV, but doesn't Falcon 9 have a common bulkhead?  Or was that only Falcon 1?  The S-II was a development nightmare, but weren't the F-1 injectors also a pill?  Yet here we are eager to discuss resurrecting the one, but trying to avoid the other.

It's funny how each engineer has certain things that give them bad vibes.  "Too many engines per stage," "too many staging events," "common bulkheads are too risky," "too many different types of fuel," "too high a combustion chamber pressure," and so on.  All have perfectly logical reasons behind them, and some historical precedent, but also examples where they were contradicted to good success.  I guess that's part of the reason why no two designers produce exactly the same design.  "Let a hundred flowers bloom, let a hundred schools of thought contend."

Offline Lars_J

  • Senior Member
  • *****
  • Posts: 6160
  • California
  • Liked: 677
  • Likes Given: 195
Re: Pyrios Alternative HLV Concept
« Reply #26 on: 10/07/2013 03:47 am »

As for RP/LOX, no stage of the HLLV diameter category has ever used common bulkheads to my knowledge.   

Maybe not HLLV, but doesn't Falcon 9 have a common bulkhead?  Or was that only Falcon 1?

Falcon 9 is not "HLLV diameter". (I assume ed means 8+m diameter)

Offline M129K

  • Full Member
  • ****
  • Posts: 823
    • "a historian too many" blog.
  • Liked: 71
  • Likes Given: 290
Re: Pyrios Alternative HLV Concept
« Reply #27 on: 10/07/2013 10:51 am »
Here are a couple of the core-only concepts I like.  These use only two engine types and no strap on boosters.

 - Ed Kyle

Those look pretty neat. I do wonder, how much would performance change if you would swap the RL-10s and upper RS-68 by one and three J2X, respectively?

Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: Pyrios Alternative HLV Concept
« Reply #28 on: 10/07/2013 03:43 pm »
Here are a couple of the core-only concepts I like.  These use only two engine types and no strap on boosters.

 - Ed Kyle

Ed,

Very cool.  Thanks for the work.  But as to my previous quandry, can there simply be a scaled up Delta IV?  Rather than a 3-stage rocket?  Can you have a 10m core (or maybe 11 or 12m?) with seven RS-68A's (Assume for this they can be thermally protected enough to not fail), with say three or four RL-60's on an upper stage that also does a BLEO burn, just as the DCSS does on Delta IV now?  Or when the rocket is scaled up, does it need 3 stages?  I would think a single core Super-Delta would be more mass efficient than 7 Delta IV's, so it should at least be able to match the performance of 7 Delta IV's with just the two stages I would think.  (But I am no rocket engineer so I might be way off on that assumption.  :-)   )


Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: Pyrios Alternative HLV Concept
« Reply #29 on: 10/07/2013 04:10 pm »
Here are a couple of the core-only concepts I like.  These use only two engine types and no strap on boosters.

 - Ed Kyle

Those look pretty neat. I do wonder, how much would performance change if you would swap the RL-10s and upper RS-68 by one and three J2X, respectively?

And on the same vein, but to go back a little to Pyrios, what about the same type of medium-heavy lift class rocket  for a two launch system, but with three F-1B's, on like an 8m core, with RL/MB-60 upper stage.  But have the 1st sage be like the original Atlas, where the outter two F-1's fall off and the central F-1 does a longer burn before staging, relieved of the extra weight of engines that aren't needed any more?

Again, I look at RL/MB-60 because they were both nearly fully developed, they could be used for EELV upper stages (unlike J2X) and in fact were designed for that purpose, and they have superior ISP.  Either is really a nice sweet spot of ISP and thrust, where a small cluster of them can replace a J2X in thrust, yet a single one can replace a single RL-10 pretty easily in size and mass.  They are dimensionally about the same as an RL-10 anyway.  But trying to get J2X class thrust from RL-10's requires a very large cluster. 
So if the central F-1B burned long enough, a small cluster of like four RL/MB-60's should be adequate thrust wise to take over at staging.  And then just two of the four could be used to do the EDS burn.

Could something like that put 30-35mt to escape?  Two of those would make for a good lunar system, with LOR. 

Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: Pyrios Alternative HLV Concept
« Reply #30 on: 10/07/2013 04:39 pm »
I think the problem with scrapping the SLS core and going with F-1A core(s) is that you inevitably have to replace it with a second stage that needs 3-5 J-2X. So we're back to a Saturn-like family except perhaps with multi-core configurations.

We have these two hydrolox gas-generators. One is smaller than we'd prefer for a super-heavy rocket, and the other has rather disappointing specific impulse. It's enough for me to conclude: screw it, let's stick with the RS-25. Nobody else is going to use this stage anyway.

Butters,
You are correct if you go with a more "traditional" heavy boost core with like a 150s burn.  Because staing is so early you need a very high thrust 2nd stage.  Like the S-II.
But, if you had a longer F-1 burn.  Say a 3 core first stage where the two outter boosters jettisoned and there was a longer central core burn.  Whether that's crossfed or perhaps there's an F-1C with deep throttling like the RD-180 can do (down to 30%), then your central core can throttle back after lift off, and run throttled back while the outter boosters burn full.  Then after LRB separation, the central F-1's can throttle up as needed...which it might not need.  For three Pyrios type CCB's, if the central F-1's can throttle down to 30%, that's still about 1 Mlbs of thrust.  Or about what the S-II had.  And if they'd run mostly throttled until LRB sep, then they should have a good deal of propellant left for a 1.5 stage burn.   That way the Hydrolox 2nd stage doesn't need to have a big cluster of powerful J2X engines.  Rather, it could have perahps an RL/MB-60 powered 2nd stage.  Or possibly a combination upper stage/EDS.  The RL/MB-60 engines give some flexibility there.  High enough thrust that a reasonable cluster can overcome the gravity losses after a 1.5 stage, but still be a high performer for the latter part of ascent and/or the EDS burn.
RL-10 isn't enough thrust to use too early, and J2X is heavy and has low isp for an EDS burn.

And I keep going to Atlas V, Delta IV, and Falcon 9.  All three are two stage LV's that can put payload through escape to to GTO.  They aren't 3 stage.  And F9 uses a GG kerolox booster -and- GG kerolox 2nd stage to do it.  And somehow, if SpaceX's info is to be believed.  That 2-stage low-isp GG kerolox F9v1.1 can still get right about the same payload to GTO as the high ISP Atlas V or Delta IV.  So they're doing -something- there.  I'm just trying to pull on that thread a little here.

Basically, my whole premise with this thread, is, is there an alternative HLV to SLS that can be had? (other than Direct, AJAX, and multi-launch EELV...all of which have other threads for that)
But ultimately, in or to make any more sense than SLS for a NASA HLV, it needs to have less development elements, and perhaps some commonality with EELV.  (such as using RS-68 engines).  Otherwise, if not, then there's no advantage over the current PoR.

So, SLS will have a new core, 5-seg SRB's (although those costs could only have been saved if this had been chosen way back during ESAS), a new large upper stage, and then new advanced boosters.  It might also have a new core redesign for a 5th RS-25, and a 5m CPS depending on which way to go forward.

So, what is the dirt-cheapest and simplest and easiest HLV that wouldn't be used by anyone else?  Ultimately, I think AJAX is probably that best, but again, that's it's own thread.  I'm kinda curious about using Pyrios or scaling up Atlas V or Delta IV.

Can we do it in just two stages with just two types of engines?  With one or both engines being shared with EELV's?
That way it fits easily on the KSC MLP's, and through the VAB doors.  And there's no separate booster infrastructure to maintain. 
I do kinda like the idea of going with a 2-launch medium-heavy lift.  Something that's around 70-80mt to LEO, and 30-35mt through TLI.  And make them as cheap as possible.
It also makes available an LV that's in the class larger than EELV-heavy, without going all the way to super-heavy lift, Saturn V class.  If USAF/DoD or NASA were to have an unmanned payload that won't fit on EELV-heavy, it probably wouldn't be a 100mt payload, it's probably be a 35mt, or 40mt, or 50mt payload.  And be an incremental growth rather than a huge leap.  But it would probably be pretty rare.  Good to have an LV that can handle it, but not fequent enough to warrant scrapping the EELV fleet for a new EELV in that class.  NASA would have that covered for itself and USAF/DoD.

That's my thinking anyway.  SLS really isn't a bad option for a NASA-only HLV...especially block 1B.  Ed's performance numbers really show it's not a bad performer.  The ony better NASA only HLV would actually have to be cheaper and faster to develop, with cheaper overhead.






« Last Edit: 10/07/2013 04:40 pm by Lobo »

Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: Pyrios Alternative HLV Concept
« Reply #31 on: 10/07/2013 04:51 pm »

And I keep going to Atlas V, Delta IV, and Falcon 9.  All three are two stage LV's that can put payload through escape to to GTO.  They aren't 3 stage.  And F9 uses a GG kerolox booster -and- GG kerolox 2nd stage to do it.  And somehow, if SpaceX's info is to be believed.  That 2-stage low-isp GG kerolox F9v1.1 can still get right about the same payload to GTO as the high ISP Atlas V or Delta IV.  So they're doing -something- there.  I'm just trying to pull on that thread a little here.


Ed,
I noticed on your Space Launch Reports, you have escape velocity for the Falcon 9, but not on your pages for Delta IV and Atlas V.  I can compare the GTO performance of all 3 from your pages, and they are all very similar, but are their escape performances also about the same?  (or TLI?)
Or does the F9's low performance upper stage give it a big hit for higher energy trajectories than GTO?


Offline butters

  • Senior Member
  • *****
  • Posts: 2399
  • Liked: 1692
  • Likes Given: 597
Re: Pyrios Alternative HLV Concept
« Reply #32 on: 10/07/2013 05:09 pm »
I suppose that if we had a booster stage with better density-Isp (let's say methane staged combustion with 380s Isp), then we might be able to stage late enough to use a single J-2X second stage, especially in a triple-core configuration with cross-feed.

Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: Pyrios Alternative HLV Concept
« Reply #33 on: 10/07/2013 05:58 pm »
Here are a couple of the core-only concepts I like.  These use only two engine types and no strap on boosters.

 - Ed Kyle

Ed,

There's a Boeing AIAA paper out as of about a month ago.
"The Space Launch System Capabilities with a New Large Upper Stage"
I can't post it as it was shared with be with the instructions not to post it.
But, I did list some performances above (I'm hoping that is ok.  :-)  )

It lists performance for Block 1, and the three Block 1B configurations, four RL-10's, two MB-60's, and one J2X.
I notice your numbers for Block 1, and Block 1B with four RL-10's to LEO and escape in your drawing.
Per the Boeing paper?

LEO: 
Block 1:  LEO:  70mt
              TLI:  24mt

Block 1B (with four RL-10's)
LEO:  93.1mt
TLI:  39.1mt

Those are a little less than you are showing for Block 1 and 1B to LEO and Escape. I think Escape is usually less mass than TLI?

Just just thought I'd mention that.  Are your numbers for Block 1 and 1B a little high? (I have no idea myself)

Not sure, but I'm guessing that Block 1 will actually be closer to 70mt, despite what the ESAS report was saying for that same LV.  Probably due to the core being several mt heavier than ESAS was assuming?
And I think the 5-seg SRB's in the ESAS LV 26/27 were assumed to have HTPB rather than PBAN (ESAS page 426).
SLS vs. LV 26/27 will have less energetic PBAN and have a heavier core.  Thus I think it'll be closer to 70mt, than the 90-100mt that LV 26/27 were to have.
And I'm assuming the ICPS would do little or no ascent on a Block 1 SLS, and basically be a payload.  Just do the circ burn.  Where with Block 1B, I think the DUUS does some of the ascent.  (with propellant offload if the payload is only going to LEO, and to BLEO.  For optimal LEO performance).

Ironically, Jupiter-130 would have done about 70mt too.  It would have a lighter core (AL2195 plus being physically smaller).  Seems like the extra power of SLS is basically negated by the heavier core.  Although an SLS core should be cheaper in overhead than the Jupiter's which would have used the existing ET infrastructure.

I wonder if J-130's performances would have been similar to SLS Block 1B if it had a DUUS on top rather than the JUS?  Would a simple J-130 with a DUUS with four RL-10's have gotten 93mt to LEO?  And 39.1mt to TLI?
Not enough to get the bulk of Altair's 45mt to TLI, but if they'd just scaled down Altair a bit, and had a DUUS do LOI...they probably could have still had a lander with very similar performance to Altair!
And done it all with just an incremental transition to J-130 from STS from 2005-2011. 
Wouldn't even have needed the DUUS to be ready by 2011, just as long as Orion's SM was ready, it could have done it's own kick burn from disposal orbit to ISS's orbit I would think?  For ISS servicing.

Not sure how or if they would have still transitioned in the new FSW automation and tooling.  Probably, and would have slowly weened down the workforce at MAF.  It could have been a little more incremental though, and maybe gotten rid of the HSF gap.

But I digress...   :-)



Offline M129K

  • Full Member
  • ****
  • Posts: 823
    • "a historian too many" blog.
  • Liked: 71
  • Likes Given: 290
Re: Pyrios Alternative HLV Concept
« Reply #34 on: 10/08/2013 03:22 pm »
There's a Boeing AIAA paper out as of about a month ago.
"The Space Launch System Capabilities with a New Large Upper Stage"
I can't post it as it was shared with be with the instructions not to post it.
But, I did list some performances above (I'm hoping that is ok.  :-)  )

It lists performance for Block 1, and the three Block 1B configurations, four RL-10's, two MB-60's, and one J2X.
I notice your numbers for Block 1, and Block 1B with four RL-10's to LEO and escape in your drawing.
Per the Boeing paper?

LEO: 
Block 1:  LEO:  70mt
              TLI:  24mt

Block 1B (with four RL-10's)
LEO:  93.1mt
TLI:  39.1mt

Those are a little less than you are showing for Block 1 and 1B to LEO and Escape. I think Escape is usually less mass than TLI?

Just just thought I'd mention that.  Are your numbers for Block 1 and 1B a little high? (I have no idea myself)

Not sure, but I'm guessing that Block 1 will actually be closer to 70mt, despite what the ESAS report was saying for that same LV.  Probably due to the core being several mt heavier than ESAS was assuming?
And I think the 5-seg SRB's in the ESAS LV 26/27 were assumed to have HTPB rather than PBAN (ESAS page 426).
SLS vs. LV 26/27 will have less energetic PBAN and have a heavier core.  Thus I think it'll be closer to 70mt, than the 90-100mt that LV 26/27 were to have.
And I'm assuming the ICPS would do little or no ascent on a Block 1 SLS, and basically be a payload.  Just do the circ burn.  Where with Block 1B, I think the DUUS does some of the ascent.  (with propellant offload if the payload is only going to LEO, and to BLEO.  For optimal LEO performance).

I'm starting to doubt the "SLS is at least 90 metric tons" claim too. I tried the numbers for SLS from the Boeing alternative SLS Architecture document on L2 on the Schilling calculator. I got a payload barely over 70 tons with a 7000 kg LAS jettisoned after 330 seconds. However, on an L2 thread one of the SLS engineers (I think he was, anyway) claimed that the empty mass without residuals was actually closer to 102 tons rather than the 115 tons claimed in the Boeing paper; using that value kicks up the LEO payload to almost 90 tons again. He also claimed that 115 tons was closer to the Block II core, with an extra RS-25 and support core Advanced Boosters.  So I'd say there are three possibilities:

1. The 115 ton figure is for a strengthened version of the core that can support advanced boosters and an extra engine and the real Block 1 can actually lift 90 tons.

2. The guy was completely wrong and Boeing is right, and real payload is just a meager 70 tons.

3. Boeing is in some kind of political conspiracy to prevent the real payload from leaking out so they added 13 tons to the dry mass to give a 70 ton payload for anyone trying to check it.

It's probably number 1, at least I hope so.

Also, could you maybe give us the payloads for the other two variants?

Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: Pyrios Alternative HLV Concept
« Reply #35 on: 10/08/2013 03:45 pm »

I'm starting to doubt the "SLS is at least 90 metric tons" claim too. I tried the numbers for SLS from the Boeing alternative SLS Architecture document on L2 on the Schilling calculator. I got a payload barely over 70 tons with a 7000 kg LAS jettisoned after 330 seconds. However, on an L2 thread one of the SLS engineers (I think he was, anyway) claimed that the empty mass without residuals was actually closer to 102 tons rather than the 115 tons claimed in the Boeing paper; using that value kicks up the LEO payload to almost 90 tons again. He also claimed that 115 tons was closer to the Block II core, with an extra RS-25 and support core Advanced Boosters.  So I'd say there are three possibilities:

1. The 115 ton figure is for a strengthened version of the core that can support advanced boosters and an extra engine and the real Block 1 can actually lift 90 tons.

2. The guy was completely wrong and Boeing is right, and real payload is just a meager 70 tons.

3. Boeing is in some kind of political conspiracy to prevent the real payload from leaking out so they added 13 tons to the dry mass to give a 70 ton payload for anyone trying to check it.

It's probably number 1, at least I hope so.


Well, remember, when you see "LEO" performance, that's usually refering to a payload only going to LEO, and not BLEO.  If the payload is going BLEO, it's usually much smaller, and there's more propellant in the upper stage.  That Boeing paper gives LEO for all three DUUS configurations, each with varying amounts of propellant offload for optimal LEO performance, because too much prop in the upper stage will count against the amount of payload.  There's some curves in that paper that show the "sweet spots".  I never really understood this...although it seems pretty obivous now that I think about it.

So, for example, SLS with a DUUS with four RL-10's can put 93.1mt to LEO with a certain amount of prop offload.  So that payload isn't going anywhere else. 
That same SLS with DUUS can put 39.1mt through TLI.  So obviously there'd only be 39.1mt of payload going into LEO on that mission, and X tonnes worth of propellant and upper stage.  The fully fueled DUUS will be about 120mt, plus a 39.1mt payload, so 159.1mt.  But obviously some of the prop is burnt getting to whatever LEO is necessary prior to the TLI burn, so something less than that.  Don't know how many tonnes are required for the final part of the ascent burn.   

But anyway, yea, I am starting to think that 70mt to LEO may be accurate.  I posed the question on an SLS update thread on L2, to hopefully get some info from someone working on the project that might be able to shed some light on it.

http://forum.nasaspaceflight.com/index.php?topic=32035.msg1106630#msg1106630


Also, could you maybe give us the payloads for the other two variants?

Block 1B with two MB-60's to LEO:  97.0mt (with prop offload.  63mt usable propr for a LEO mission).  Which is the same offload for the four RL-10's.

Block 1B with one J2X to LEO:  105.2mt (with prop offload.  95mt usable prop for a LEO mission)


Obviously the J2X is the best performer to LEO.  But SLS isn't supposed to really be doing LEO mission.  And for BLEO missions, it's performance defficiency vs. the other two engine options gets more pronounced the farther out you go.  Although it's not much of a defficiency for lunar missions.  Only about 1mt.

Myself, I'd kinda like to see a DUUS like the ACES proposal, one that could mount two or four MB-60's depending on the mission.  For a LEO mission it could mount four, and probably get about the J2X performance to LEO.  For BLEO it could mount just two, and then get that benefit of it's superior ISP.


Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: Pyrios Alternative HLV Concept
« Reply #36 on: 10/08/2013 05:32 pm »
The big question I have (as I posted on the L2 thread) is if SLS Block 1 can only deliver 70mt to LEO (I think that assumes the core does the full ascent to disposal orbit, with the payload/ICPS just doing a circ burn.  Where the DUUS on Block 1B will do some of the ascent and thus the higher performance to LEO).

But if the core with 5-seg SRB's can only put 70mt in LEO...why did they go with the stretched core and 5-seg boosters at all?  Jupiter-130 (aka LV 24/25 from the ESAS study) could do a little over 70mt to LEO without an upper stage either, using a smaller core, 4-seg Shuttle boosters, and one less RS-25 on the core.

Why could they have just used that and put a DUUS on it?  And if they wanted more performance, they could have put advanced boosters on that core too.  Both the 5-seg SRB's and also various LRB concepts were considered for STS, so there's not reason longer boosters couldn't have been used on the shorter core/ET. Pyrios boosters could have been made back in the 90's and used on STS to increase it's payload capacity.  And the 5-seg booster for CxP was actually previously already considered for STS as an upgrade over the 4-seg with minimal infrastrcture changes to KSC.

So they could have done a Jupiter-130/LV24/LV25 with the old STS boosters and got about 72mt to LEO.  Or put the 5-seg on them (by 2011, the birth of SLS, 5-segs where already well into development.) 
Although, you could have still went with 5-1 seg boosters.   

It seems like the larger core size, the heavier alloy used, the extra engine, and the larger SRB's ended up adding enough extra mass to negate the extra thrust.  And just ending up with a larger LV with the same performance.

So I wonder why the streched core, extra engine, and bigger SRB then?

Or would J130/LV24/LV25, have actually needed the heavier and thicker AL2219 to overcome the bending load that would be put on it in an inline core rather than a side mount ET?  Maybe the performance of J130/LV25/LV25 would have been 20mt less than ESAS and Direct predicted?  Just as SLS Block 1 is about 20mt less than ESAS had for the LV26/27?  In which case then it might make more sense to stetch the core with the extra engine and 5-seg boosters to get that performance back up?

I dunno, but it's go me scratching my head....





Offline M129K

  • Full Member
  • ****
  • Posts: 823
    • "a historian too many" blog.
  • Liked: 71
  • Likes Given: 290
Re: Pyrios Alternative HLV Concept
« Reply #37 on: 10/08/2013 06:40 pm »
I think a J-130 core would not have been able to support an upper stage big enough to reach the 130 ton mandate. The Block 1 core in it's current form probably can't either, but the heavier core designs that result in 70 ton payload estimates can. They are designed to take much more stress from advanced boosters, a fifth RS-25 and a large J-2X upper stage and/or a DUUS with a 130 metric ton payload. The initial Block 1 core isn't adapted to these things, only for a DUUS, and could still lift about 90 tons to LEO. The later Blocks would have a much heavier core stage though, and any "Block 1" that will fly after this core design has been taken into service will likely use the much heavier Block 2 core for increased commonality, reducing payloads with standard boosters to 70 tons.

At least, that makes sense to me. I think.

Offline Lobo

  • Senior Member
  • *****
  • Posts: 6915
  • Spokane, WA
  • Liked: 672
  • Likes Given: 437
Re: Pyrios Alternative HLV Concept
« Reply #38 on: 10/08/2013 11:38 pm »
I think a J-130 core would not have been able to support an upper stage big enough to reach the 130 ton mandate.

Well, I think the J-246 common core was designed to handle the JUS (which I think is a bigger and heavier stage than the DUUS, as it was designed to do to more ascent than the DUUS).  The J-246 was to put something like 108mt into LEO, so about the same as SLS BLock 1B with J2X engine.  And I understand they are currently designing the SLS core for Block 1B loads, rather than Block 1, or Block II.

And keep in mind that the taller the stack means higher bending loads.  Which means it needs strengthening.  Remember, Jupiter or SLS has top-lift construction, so the core doesn't need with withstand the loads of the boosters.  That is all transferred to the upper thrust beam.  The boosters are actually lifting the core up, with the RS-25's pushing up from the bottom. (enough to keep the core in compression).
So, you could add big, bad, Pyrios boosters to a J-130/246 common core  just like you could to SLS.  the core doesn't see those thrust loads.  And it would be a lighter, and shorter core, which would have less bending loads after booster separation.  Which could result in -less- strengthening than SLS needs.

That's kind of the counter-intuitive nature about this top lift sustainer core type of deisgn.


The Block 1 core in it's current form probably can't either, but the heavier core designs that result in 70 ton payload estimates can.


That is possible.  But I doubt that accounts for the 20+mt diferential.  Optimizing for Block 1 probably won't get 90+mt to LEO.  Probably more like 75 or 80mt best case. (in my uneducated guess).


They are designed to take much more stress from advanced boosters, a fifth RS-25 and a large J-2X upper stage and/or a DUUS with a 130 metric ton payload. The initial Block 1 core isn't adapted to these things, only for a DUUS, and could still lift about 90 tons to LEO.


Again, as I understand, the Block 1 core is being design for Block 1B loads.  I don't think the 5th RS-25 is being included in it at all, and thus that upgrade option -will- require a core redesign.  (another arguement to go Block 1B then 2B). 
Also, think about the advanced boosters, especially Pyrios.  Yout think the core needs strengthened, but why?  The 5-seg SRB will have about 3.5Mlbs of thrust at liftoff each.  How much will Pyrios have?  About 3.6Mlbs.  That's very similar. 
Now, during the boost phase, the Pyrios boosters extra ISP might result in greater acceleration potential than the SRB's, but NASA has limits to how much acceleration they'll allow for a man-rated LV.  So there will probably be a system of throttling back the core and the F-1B's to keep it from accelerating too fast and pulling too many G's, and thus, incurring excessive compression and bending loads.
So other than modifying the booster interfaces (and all of the infrastructure to to switch from SRB's to LRB's) the BLock 1B SLS might not need any further core upgrades to mount Pyrios LRB's
Aerojet LRB's with 4Mlbs of thrust could be a little more of an issue.  But I think the AJ-1E6 will have a deeper throttle like the NK-33's, and so they can still be throttled down to keep the loads on par with block 1B.
The main issue could be advanced solids, which would have about 4.5Mlbs thrust per the ATK paper.  That's 2 Mlbs more power total at liftoff than the Block 1B 5-segs.  But ATK could design the propellant to self throttle a little more to keep it's acceleration profile within acceptable limits.  Just as the 4-segs did and the 5-segs will do. Max thrust at liftoff to get going, then tapering down during boost to keep acceleration down.

One of the biggest issues to require a core redesign for Block 2, is the 5th RS-25, and a taller stack that results form a large J2X upper stage, along with a CPS...and then the payload on top of THAT.  A taller stack means more bending loads, and that means more core strengthening.

(FYI, this was all discussed with some of the folks in the know on one of the L2 threads.  So it's not just me being smart.  It's only what I picked up.  :-)  )


The later Blocks would have a much heavier core stage though, and any "Block 1" that will fly after this core design has been taken into service will likely use the much heavier Block 2 core for increased commonality, reducing payloads with standard boosters to 70 tons.

At least, that makes sense to me. I think.

Again, the core would only probably need to be any heavier than the original design if one of the options invoving a taller stack is chosen.  The core isn't taller, but instead of just a DUUS (which the core's being designd for now), and the max sided PLF on that, you'd have a J2X upper stage which would probably be larger than the DUUS to feed one or two J2X's, and would do more ascent because the core would burnout faster with the extra engine.  THat gives that bump in performance.  Then there'll be a CPS on top of that, and the PLF on top of that.  With and extra interstage.  Probably be a good 10+ meters taller I'd think?
IF not more.  And those would need to be accounted for.
But going from Block 1B to Block 2B will keep four RS-25's and -may- not actually require any core redesign or strengthening.

Anwyay, I suppose a question for one of the Direct gusy would be, how much did the core strengthening of the J-246 over a core optimized for a J-130, impact it's performance?  I think I remember them saying they could launch the J-246 core without the JUS and without the 4th RS-25 engine, and it's still have about 70mt to LEO performance.  If so, that's about a 2-3mt performance hit.
Or would it be more severe?  like 20mt? And a J-246 core with three engines and no JUS would only get like 50mt to LEO?
I don't really know.  Maybe Chuck or someone can comment about that.

Anyway, I may have gotten us a little OT with my post on Ed's SLS performance numbers.  :-)
Just seeing that Boeing number of 70mt on SLS Block 1 got me a little confused and windering why maybe a smaller core and boosters that could have done 70mt wasn't used if that's all this got.
Also, Downix seemed to get an AJAX core that was even a little smaller than the Jupiter core, to support paylaods of 130mt.  I think he used a type of butress system to support the boosters from the bottom, rather than just thickening up the core to support the bottom lift Atlas boosters.




Offline M129K

  • Full Member
  • ****
  • Posts: 823
    • "a historian too many" blog.
  • Liked: 71
  • Likes Given: 290
Re: Pyrios Alternative HLV Concept
« Reply #39 on: 10/09/2013 05:17 pm »
I was going off of what I read in another thread. It was from the Boeing alternative architecture thread. Advanced boosters will most likely require a core redesign.

Tags:
 

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