Author Topic: Advanced boosters progress towards a solid future for SLS  (Read 30070 times)

Offline TomH

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #80 on: 03/03/2015 03:52 AM »
Interesting: RAC I "Pros":

Shuttle derived architecture consistently provides early, highly capable solution:
-Existing assets provides a fast, low cost start-flight test
-Acquisition options provide a fast start

May have been true for Jupiter-130, but I wouldn't exactly call what we're getting heritage/legacy hardware, nor "fast" or "low cost". Hyperion V is right, rebuilding Saturn V with F-1A/B and J-2-X may have been better.  The Raptor BFR will make it all a moot point anyway, though Shelby & Co. will keep funding SLS until they retire.

« Last Edit: 03/03/2015 03:53 AM by TomH »

Online Lars-J

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #81 on: 03/03/2015 04:21 AM »
"Shuttle derived" was never about the hardware. Just the contractors behind it. "Shuttle contractor derived" is what we ended up with.

Now it had been about the hardware (minimal mods), resulting in a Jupiter 130, then the decision would have made sense. But that was never the plan.

Offline The Amazing Catstronaut

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #82 on: 03/03/2015 07:18 AM »
Awh.
It was personally a pet fetish of mine that I'd be able to see the SLS torch the heavens with those F1b boosters. Damn, that would have been a sight to behold.

The Dark Knights do seem like the best choice out of a bad lot. Besides, SRBs are something that ATK have a proven history of producing to a high standard. I'm comfortable with it.
Resident feline spaceflight expert. Knows nothing of value about human spaceflight.

Online spacenut

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #83 on: 03/03/2015 03:33 PM »
Will the Dark Knights be reusable like the steel casings were? 

Offline mike robel

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #84 on: 03/03/2015 04:15 PM »
No

Online spacenut

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #85 on: 03/03/2015 04:20 PM »
Any reason why?  Is it because of the initial stress on the composite, that it can't take any more stress?  Or just not cost effective. 

Offline TomH

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #86 on: 03/03/2015 04:40 PM »
Any reason why?  Is it because of the initial stress on the composite, that it can't take any more stress?  Or just not cost effective.

Not cost effective and also weight/aerodynamics penalties. Weight of parachutes, true conical nose cone not as aerodynamic, etc. reduces payload mass. Don't know about composite stresses.

Offline notsorandom

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #87 on: 03/03/2015 05:48 PM »
The filament wound boosters meant for shuttle missions out of Vandenberg I believe were to be reusable. The Dark Knight boosters could likely be made to be reusable too. There would be a hit to SLS's payload. That might be made up for by the increased performance of the boosters. However the economics are the primary reason neither the 5 segment boosters or the Dark Knights will be reused. At low flight rates reusability costs more. Even at the highest historical flight rate of STS the economics of booster recovery and reuse was iffy. Recovery of the boosters did allow inspection making the system potentially safer and more reliable. The ability to recover boosters was built in to the Ariane 5 for this reason. Though no reuse was ever planned several of the early mission's boosters were recovered for inspection.

Offline Lobo

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #88 on: 03/03/2015 09:20 PM »
As I understood, at the flight rates of of STS, the cost of reuse vs. new was about a push.  Essentially, the reusability of the boosters was good for publicity but didn't pencil out economically unless there were several more launches per year.

When CxP was first incepted, I believe (someone correct me if I'm misremembering) they were going to go with HTPB propellant in those same STS steel casings for additional performance vs. just the 5th segment.  And then as the flight rate wouldn't be any more than STS wtih Ares 1 and V combined, they decided not to develop a parachute kit for the 5-seg.  (as they were heavier, the STS parachute kit would be too small and a new one would need developed).  All of the custom facilites that made the casings would actually get utilized more without reuse, justifying carrying their overhead better.  (A similar thought to having an RS-25E, there'd be enough production rate to justify a new modern version of the SSME.) 

Somewhere along the line, HTPB was dropped in favor of legacy PBAN, but the 5-seg booster remained.  After CxP was cancelled, the steel booster facilites were shut down and as discussed, cannot be restarted.  They'd have to be built new again.

So with a transition to composite casings, they -should- be cheaper to make annually than the steel casings as they don't need to be forged and heat treated and such.  They could possibly me made reusable I imagine...at additional expense...but at stated, the economics of reusability don't pencil out at even STS flight rates, much less SLS flight rates.  And as they are cheaper to make, that's even more reason not to try to reuse them a one launch per year or every 2 years.

Offline clongton

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #89 on: 03/03/2015 11:59 PM »
Sorry. Somebody said that we have SRBs because of the infamous "130t requirement" I was trying to point out that it's more like we have SRBs in spite of said requirement.

We have SRBs because of the "shuttle derived" and schedule desires. But when it comes to the "130t requirement" they need either 1. a new core or 2. LRBs or 3. ignore 130t language.

We have SRB's because of the incredible amount of influence ATK has over our elected officials - period. When you have a stranglehold on the nation's defenses you can pretty well get whatever you want - even if it is not in our best interest, which SRB's are not. LRB's best SRB's in every category, but none of that matters. It has never been about what is best for the HSF program. If it had been we would be talking about the new LRB's.
« Last Edit: 03/04/2015 12:02 AM by clongton »
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Offline edkyle99

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #90 on: 03/04/2015 12:34 AM »
We have SRB's because of the incredible amount of influence ATK has over our elected officials - period.
ATK's influence paled in comparison to Lockheed Martin, Boeing, and the like, companies that spent ten times more on lobbying and campaign contributions than did ATK.  Gencorp, owner of Aerojet Rocketdyne, spends just as much as ATK on lobbying.  It lost the chance to build SLS booster propulsion not because it didn't lobby as much, but because it had nothing ready to offer to do the job.   

 - Ed Kyle

Offline TomH

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #91 on: 03/04/2015 12:50 AM »
We have SRB's because of the incredible amount of influence ATK has over our elected officials - period.
ATK's influence paled in comparison to Lockheed Martin, Boeing, and the like, companies that spent ten times more on lobbying and campaign contributions than did ATK.  Gencorp, owner of Aerojet Rocketdyne, spends just as much as ATK on lobbying.  It lost the chance to build SLS booster propulsion not because it didn't lobby as much, but because it had nothing ready to offer to do the job.   

 - Ed Kyle

It didn't lose the chance, as it never had a "chance" because there was no competition. There was no competition because of the cost to modify the pad and tower.
« Last Edit: 03/04/2015 12:51 AM by TomH »

Offline woods170

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Re: Advanced boosters progress towards a solid future for SLS
« Reply #92 on: 03/04/2015 09:14 AM »
Note: Any discussion about the political background of SRB's or LRB's belongs in the space policy section.

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