Author Topic: Delta 4 based advanced boosters  (Read 17506 times)

Offline FinalFrontier

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Re: Delta 4 based advanced boosters
« Reply #20 on: 04/05/2013 05:31 am »
Lobo's thought experiment about using Falcon cores as SLS boosters is a good way to think about how to keep development costs down. I still prefer the idea of using dual delta 4 tank sets on each side with a new thrust structure that would support 4 RS-68A engines for a total of 2.8 million pounds thrust per side.  Only eight engines, using the same LH2 as the SLS core and with a potential for a flyback version in the future.
This would seem to require only a new thrust structure and external attachment frame to put it into the running as an alternative to designing a entirely new booster.

No its not that would never work. Horrible suggestion.
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Offline Lobo

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Re: Delta 4 based advanced boosters
« Reply #21 on: 04/05/2013 04:34 pm »
Lobo's thought experiment about using Falcon cores as SLS boosters is a good way to think about how to keep development costs down. I still prefer the idea of using dual delta 4 tank sets on each side with a new thrust structure that would support 4 RS-68A engines for a total of 2.8 million pounds thrust per side.  Only eight engines, using the same LH2 as the SLS core and with a potential for a flyback version in the future.
This would seem to require only a new thrust structure and external attachment frame to put it into the running as an alternative to designing a entirely new booster.

No its not that would never work. Horrible suggestion.

Yea, I think Delta IV would be much harder to make into boosters than Atlas V or Falcon 9.  It's a fun exercise nonetheless.

I think probably the only real way to have Delta IV derived boosters for SLS is to directly mount multiple cores to the SLS core directly like AJAX (but obviously that won't happen, as NASA won't redesign the SLS core as has been discussed on these hypothetical theads).
OR...widen the core up to 10m, and put a jettisonable engine ring of RS-68A's around the bottom like Saturn V-B.  Keep RS-25's under the core in a four-engine tight cluster, but have like six RS-68A's outboard that all fall away during ascent.  Then you get rid of the cheap RS-68's early, but keep the high performance RS-25's all the way to suborbit.
Keep the RS-68A's pushed to the outter dimension so they aren't trapped under the core exposed to hot gas buildup. 
Maybe it a 1.5 stage to orbit core.
That's a completly different core than current SLS though...although kind of a cool concept.  So probably best to steer clear of hydrolox "boosters" for it.

Offline edkyle99

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Re: Delta 4 based advanced boosters
« Reply #22 on: 04/05/2013 07:37 pm »
This seems to be the most stupid "SLS improvement idea" I've yet seen.

Hydrolox for boosters?

Hydrolox has a very good isp, but loses to kerolox on practically all other aspects (thrust/weight, price/weight, tankage size).
LOX/RP beats LOX/LH2 on size and, all other things being equal, on cost - but not by a large margin. 

Shuttle LRB studies by Martin Marietta and GD during the late 1980s showed that LOX/RP boosters had a less than 5% operational cost advantage over LOX/LH2 boosters.  GD nonetheless recommend LH2 (Martin Marietta went with RP). 

The difference today is that RS-68 exists, while the RP engine does not, which would make a big difference in development costs.  RD-180 exists, but would need to be built in the U.S., which would make it $$$$.  A gas-generator RS-68 might even beat a U.S.-built staged combustion RP engine on production cost.

RS-68 is a booster engine, so merits consideration - though I would suggest only for a new 5.5+ meter diameter booster.  T/W is not an issue, because an LH2 booster will only weigh 70% as much as an RP booster.  LH2 requires LESS thrust, and thrust costs money. 

RS-68 is good enough for NRO and its multi-billion dollar satellites.  Why not SLS?

 - Ed Kyle 
« Last Edit: 04/05/2013 07:41 pm by edkyle99 »

Offline sdsds

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Re: Delta 4 based advanced boosters
« Reply #23 on: 04/06/2013 04:39 am »
Maybe it's worth stating the obvious: this would be a version of SLS powered by Rocketdyne engines. (SSME, RS-68, J-2X.) One would expect that for this design to get much consideration Rocketdyne would need to champion it. That might be difficult for them right now. The acquisition of Rocketdyne by GenCorp was expected to close in the first half of 2013. Any word on that?
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Offline a_langwich

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Re: Delta 4 based advanced boosters
« Reply #24 on: 04/07/2013 02:50 am »
This seems to be the most stupid "SLS improvement idea" I've yet seen.

Hydrolox for boosters?

Hydrolox has a very good isp, but loses to kerolox on practically all other aspects (thrust/weight, price/weight, tankage size).
LOX/RP beats LOX/LH2 on size and, all other things being equal, on cost - but not by a large margin. 

Shuttle LRB studies by Martin Marietta and GD during the late 1980s showed that LOX/RP boosters had a less than 5% operational cost advantage over LOX/LH2 boosters.  GD nonetheless recommend LH2 (Martin Marietta went with RP). 

The difference today is that RS-68 exists, while the RP engine does not, which would make a big difference in development costs.  RD-180 exists, but would need to be built in the U.S., which would make it $$$$.  A gas-generator RS-68 might even beat a U.S.-built staged combustion RP engine on production cost.

RS-68 is a booster engine, so merits consideration - though I would suggest only for a new 5.5+ meter diameter booster.  T/W is not an issue, because an LH2 booster will only weigh 70% as much as an RP booster.  LH2 requires LESS thrust, and thrust costs money. 

RS-68 is good enough for NRO and its multi-billion dollar satellites.  Why not SLS?

 - Ed Kyle 

RS-68A exists, but does not have the safety margins or instrumentation NASA would demand to launch people.  In study after study where RS-68s were clustered together, the inability of the existing nozzles to withstand those thermal conditions have been highlighted.  The fuel rich startup also highlights a condition which would need redesign.  There are a handful of prototypish (RS-84), past-production (F-1), or variations of current production (AJ-26) kerolox hardware out there.  (SpaceX of course has M1D in production now.)  I suspect some of those would not be too different in development cost than modifying the RS-68.

Rather than arguing about what will cost how much, that's a question easily decided by the bidders on an advanced booster contract.  If, that is, the bidder can muster the credibility they can execute said design for the bid amount--that's probably why NASA has paid(?) Dynetics to do some exploratory work.  If some enterprise can win the bid with an RS-68 booster, I'm all for it. 
 
Production cost is not likely to be a factor here, the cost of infrastructure to allow continued production will continue to be the cost driver IMO.  On production cost, (expendable) solids would clean up, would they not?  RS-68's wonderful production cost hasn't helped Delta IV be very competitive on cost grounds, has it? 

Why isn't thrust-to-weight an issue?  Doesn't the booster have to help lift not just its own weight, but help with the core and up?  And true, LH2 is lighter, but it's larger, and doesn't that structure carry weight?  Doesn't an Atlas 5 core have a large T/W than a Delta IV core?  Thrust costs money, so why is Atlas 5 the preferred single-core ULA offering?  I'm not arguing these in terms of hypothetical hydrolox vs kerolox, we are actually talking about Delta IV hardware, and an AJ-26 based kerolox booster might be similar to Atlas hardware.

Offline robert_d

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Re: Delta 4 based advanced boosters
« Reply #25 on: 04/07/2013 03:41 am »

The further alternative would be to use the STS main engine reusable version.  Production could be restarted in parallel to the expendable version for the core. It was a tragedy that just as this engine was mature enough to justify reuse vs. disposal the space shuttle was cancelled. The additional gain in ISP trumps any of the arguments for kerolox, IMO.  About six would be needed per side and could be built into the new adapter that would replace the current thrust structures and interface with the SLS core. This would eliminate ANY cost for upgrades and manrating beyond what will be incurred by the RS-25E program.

Also note that what is considered a detriment fo hydrolox by some (the larger tank size) actually becomes a benefit if the floatback concept could be implemented, in that the large volume of the H2 tanks would be filled with hydrogen gas, thus reducing the size of the external inflated blimp-like gas bag.  Floatback would be slow and gracefull with airbags deployed so that the booster would land horizontally.  Once the hydrogen was purged, it could be towed back to a horizontal integration facility.  No fast deceleration, landing legs, or other time critical events required once the gas bag is inflated.
   

Offline edkyle99

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Re: Delta 4 based advanced boosters
« Reply #26 on: 04/07/2013 05:28 am »
Why isn't thrust-to-weight an issue?  Doesn't the booster have to help lift not just its own weight, but help with the core and up?  And true, LH2 is lighter, but it's larger, and doesn't that structure carry weight?  Doesn't an Atlas 5 core have a large T/W than a Delta IV core? 
Liftoff thrust to weight ratio is the same for Delta 4M and Atlas 5-401.
Quote
Thrust costs money, so why is Atlas 5 the preferred single-core ULA offering?
In part because it uses Russian-built engines that cost less than U.S. built engines. 

 - Ed Kyle

Offline MATTBLAK

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Re: Delta 4 based advanced boosters
« Reply #27 on: 04/07/2013 05:54 am »
In our many forays into 'Rocket Lego' I don't remember but has anyone ever crunched the numbers for a Delta IV core with 2 and/or 4 Atlas V cores as strap-ons? ('3 stick' & ''5 stick' configurations, with various upper stage options).
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Offline Proponent

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Re: Delta 4 based advanced boosters
« Reply #28 on: 04/07/2013 03:23 pm »
Liftoff thrust to weight ratio is the same for Delta 4M and Atlas 5-401.

On the other hand, the thrust-to-weight ratio of a lower-Isp booster like the Atlas necessarily increases faster.
« Last Edit: 04/07/2013 03:24 pm by Proponent »

Offline edkyle99

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Re: Delta 4 based advanced boosters
« Reply #29 on: 04/07/2013 04:11 pm »
Liftoff thrust to weight ratio is the same for Delta 4M and Atlas 5-401.

On the other hand, the thrust-to-weight ratio of a lower-Isp booster like the Atlas necessarily increases faster.
Yes, resulting in a bit less gravity loss, which the LH2 rocket makes up for in part by working at higher ISP. 

Upper stage differences account for much of the performance differences between the two EELV Mediums.  Centaur weighs several hundred kilograms less than the 4-meter DCSS at burnout, despite carrying more propellant, which translates directly into more payload.

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Offline edkyle99

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Re: Delta 4 based advanced boosters
« Reply #30 on: 04/10/2013 04:31 pm »
This article says that RS-68 costs have dropped 30% as a result of the EELV block buy.

http://www.spacenews.com/article/launch-report/34773pwr-sees-better-days-ahead-after-post-shuttle-dropoff#.UWWTnUq1Uyd

 - Ed Kyle

Offline edkyle99

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Re: Delta 4 based advanced boosters
« Reply #31 on: 04/11/2013 04:36 pm »
Here's a look back at Advanced Booster concepts circa 2001, as reported by MSFC.  The RS-68 booster then envisioned used five engines for ATO, etc., which is more than needed for SLS.  The height constraint mentioned for the Shuttle application does not apply to SLS.

 - Ed Kyle
« Last Edit: 04/11/2013 04:46 pm by edkyle99 »

Offline a_langwich

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Re: Delta 4 based advanced boosters
« Reply #32 on: 04/11/2013 05:01 pm »
Why isn't thrust-to-weight an issue?  Doesn't the booster have to help lift not just its own weight, but help with the core and up?  And true, LH2 is lighter, but it's larger, and doesn't that structure carry weight?  Doesn't an Atlas 5 core have a large T/W than a Delta IV core? 
Liftoff thrust to weight ratio is the same for Delta 4M and Atlas 5-401.

Ah, I see.  I had looked up the datasheets on your website, but didn't notice the Atlas 5 CCB thrust figures were vacuum, while I had used Delta IV CBC thrust figures for SL.

Offline Lobo

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Re: Delta 4 based advanced boosters
« Reply #33 on: 04/11/2013 05:09 pm »
This article says that RS-68 costs have dropped 30% as a result of the EELV block buy.

http://www.spacenews.com/article/launch-report/34773pwr-sees-better-days-ahead-after-post-shuttle-dropoff#.UWWTnUq1Uyd

 - Ed Kyle

Ed,
I think you've made the case for the RS-68A of being a viable booster engine (and NASA is evaluating it from the sounds of things, along with the F-1B and a large ORSC kerolox engine).
But, unless we could mount the entire D4H to each side of the SLS core (which I don't think we can based on the width in that direction of the ML opening per the Advanced booster solocitation, that dimension is only like 9.3m, and D4H will be over 15m in that direction...even FH will be too long that way), and since I don't see NASA redesigning the SLS core to mount the booster directly like AJAX, I just think any monolithic hydrolox core would have to be too wide to mount the three RS-68A's required.  I think that's the problem with going with hydrolox boosters using RS-68A's.  (although maybe I'm wrong on that).

Not to go OT, but your arguments did get me thinking about other hypothetical options...very hypothetical...

Maybe if the SLS core was shrunk down to about 6.5m wide.  Then it could mount two 6.5m wide hydrolox boosters.  (NASA seems adverse to having more than two boosters period, so I'm exploring this route).
So you have basically a D4H on steroids, each using RS-68A.  If they were long enough, maybe they could have a four RS-68A MPS, but the central core would only mount two RS-68A's when launching with boosters, so it would burn longer.  The outboard cores would have four engines, and burn out faster and be jettisoned.  That'd be about 6.4Mlbs of thrust at liftoff. 
RS-68A's aren't as efficient when used as a sustainer, I understand, but maybe the "Block 1B" upper stage, which would be 6.5m wide now, could be longer with like six RL-10's, so they can do more of the ascent boost than current Block 1B upper stage would, and stage sooner.  Maybe more like a JUS.  (A J2X could be an option on it too)
Such a system could launch as a single stick too, with the same upper stage, and four RS-68A's on the core, and stage earlier with the upper stage doing more of the ascent. 
It'd have a modified (shorter) upper thrust beam like STS/SLS, but that would be left off for a single stick launch.
This would require RS-68A to be man-rated of course, unless this was the cargo-only heavy lifter and Orion was launched on Atlas V-55x with a new 5m common upper stage (Jim said once that that LV could lift a fully fueled Orion to LEO) and return to the 1.5 launch system.  Then this HLV would not need to be man-rated. 
Iíll assume if this could get around 110mt or so to LEO, then with Orion launching on Atlas V, the combined LEO capacity could be the mandated 130mt.
If the SLS will be about 200ft tall, then Iíd assume a similar length for the 6.5m cores.  Hopefully thatís enough for four RS-68A engines.  (They could even mount some GEM-60ís each.  More synergy with EELV and again, itís a cargo launcher).

Yea, I know itís probably too much divergence form the baseline SLS core to be in the realm of ďreasonableĒ hypothetical, but really, with no metal bent, itíd just be redesigning to make about 2m skinnier.  The booster mounts and upper thrust beam would be pretty similar.  Height for the tower would be about the same.  Itís just shrinking the core and fattening up the boosters, and making all 3 cores common.  Delta IV booster mounts could be used on the bottom, for more synergy.  Most things would actually remain the same.  Those RS-68A prices would probably drop even more.

Any idea of the capacity of something like that?

Offline Lobo

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Re: Delta 4 based advanced boosters
« Reply #34 on: 04/11/2013 05:22 pm »
Here's a look back at Advanced Booster concepts circa 2001, as reported by MSFC.  The RS-68 booster then envisioned used five engines for ATO, etc., which is more than needed for SLS.  The height constraint mentioned for the Shuttle application does not apply to SLS.

 - Ed Kyle

Ahhh...I posted mine before I saw you just posted this.

Well, 5.8m wide and 200ft tall could feed five RS-68's?  Is that with a burn time similar to the STS 4-seg SRB's or something?  I wouldn't think that'd be enough volume to feed five engines for every long. 
But, I suppose you really only need a burn time similar to SRB's, the three RS-25's on the orbiter are designed to take over the ascent from SRB sep.  Although, would hydrolox boosters separating at the same time as the STS 4-segs accelerate STS to the same speeds?  Or do they need a longer burn to get the same speed before separation?

Today, with maybe four RS-68A's on each, and making them just a bit narrower to about 5.5 or 5.6m (5.76 the absolutely max?), and keeping the same height, that could be a viable booster for SLS.  The four RS-25's on the core are designed to take over ascent after SRB separation at about 124 seconds into launch, although again, would the core be going the same speed with 124 seconds of burn from hydrolox boosters as it will be from 5-seg SRB's? 

Doesn't the extra SRB thrust give it better accelleration during those first two minutes?

Anyway, to dovetail on my earlier post, fatten these up to about 6.5m, and launch two of them on an identical 6.5m core all with RS-68A's.
Maybe five engines on the boosters, and 2 on the core.  The core won't go all the way to orbit probably with the low ISP RS-68A's, but it could burn for longer than the boosters.  Maybe burn for 6 minutes and let the upper stage do the rest?

Offline Lobo

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Re: Delta 4 based advanced boosters
« Reply #35 on: 07/15/2013 10:24 pm »
Here's a look back at Advanced Booster concepts circa 2001, as reported by MSFC.  The RS-68 booster then envisioned used five engines for ATO, etc., which is more than needed for SLS.  The height constraint mentioned for the Shuttle application does not apply to SLS.

 - Ed Kyle

Ed,
How many RS-68's would be needed for SLS?

Five RS-68A's would produce about as much take off thrust as the 5-seg booster or two F-1B's.

Would three be enough?  Or not enough thrust?

The five RS-68 version would be interesting, especially if the four outter engines could be jettisoned like the S-1D or Atlas.  Not so much as a booster advantage, but if say ULA were to want to bid this "Delta derivative" CCB for the SLS Advanced booster competition, and if successful, they were to retire Delta IV entirely, let Atlas V take over the Delta IV-medium work, and let this booster replace the D4H for that 25mt range.

The outter four RS-68's are jettionsed at maybe 120-150 seconds into flight, with the core burning for perhaps another 150-200 seconds with the single RS-68A.  Then a 5m DCSS or probably better yet, ACES on top.

A variation could be having an SLS RS-25E in the central mount, and letting that engine burn the core almost to orbit.  (Especially if the central RS-68A would have base heating problems) Maybe not the cheapest 25mt class vehicle, but it'd use existing engines, an existing core (if ULA were to compete and win the booster competition), and an existing upper stage.  Even the DCSS would give good BLEO capability with a sustainer core burning almost to orbit with an RS-25E.

The booster version could omit the central mount entirely, and run the RS-68A's at full throttle for longer until the booster are burnt out. They could omit the hardware needed to jettison the ring too for the booster version.

Seems pretty unlikely that ULA would retire the 5m D4 CCB for this, but in a hypothetical world where they would be interesting in getting that SLS booster work, it's not completely inplausible as D4-medium is redundant with Atlas V, and this CCB would be redundand with D4H. (Since we've established that a tri-core D4H is inplausible to use as a booster itself...as was the genesis of this thread).
It would add two engines to the LV over D4H, but also remove two cores.

A smaller version could be three RS-68's in line on that aft skirt, but I'm not sure if only three would be enough thrust for SLS in the booster configuration?  Be fine I think for a D4H class replacement.

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