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#500
by
sdsds
on 03 Aug, 2011 19:02
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The Delta Mariner uses the dock at VAFB that was intended for shuttle ET's.
The Delta Mariner is a RO RO (like the ET Barge) and only a Delta IV EPT (transporter) is needed to remove the core for Delta. The Atlas core had its tractor with it.
Why would cores be delivered to Michoud?
This goes slightly off topic but it really is about the newly expanded Delta Mariner capabilities.
For a design like AJAX there are (at least) two different scenarios for how Atlas CCBs would get to the VAB by water transport. One is that Delta Mariner would take them directly to the turn basin and offloads them there. It can get there and do that? If for any reason it couldn't, the cores could presumably be cross-loaded onto Pegasus at Michoud.
The AJAX theory is that the CCBs could be used completely unmodified ("white tail"). But if it turns out they can't, the motivations for the USAF white tail requirement might be at least partially addressed by modifying the cores at some location outside Decatur. So the other imaginable scenario for Michoud delivery is where, for whatever reason (e.g. political), work to modify the CCBs for AJAX is given to Michoud rather than KSC.
More generally, Vitter has done a pretty good job keeping Michoud relevant in the changing world of NASA exploration systems.
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#501
by
JosephB
on 11 Aug, 2011 13:48
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Hypothetical question:
What is the current max number of DIVH flights that could be flown per year if only heavies were flown?
EDIT: from Florida
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#502
by
kcrick
on 30 Jan, 2012 14:05
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Not sure if this is the proper thread and forgive me if it's been answered already (I've done some digging here and didn't find an answer), but I'm curious - what route does the Delta Mariner take from Decatur, AL. to the Cape to deliver rocket stages, etc. ?
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#503
by
baldusi
on 30 Jan, 2012 14:18
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Another question. With the RS-68A, the Medium fleet is standardizing its body to the M+(5,4), right? Are they also moving to AlLi?
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#504
by
notherspacexfan
on 30 Jan, 2012 14:35
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Not sure if this is the proper thread and forgive me if it's been answered already (I've done some digging here and didn't find an answer), but I'm curious - what route does the Delta Mariner take from Decatur, AL. to the Cape to deliver rocket stages, etc. ?
Two ways to go
1. Tennessee river - Ohio river - Mississippi
2. Tennessee river - Tennessee–Tombigbee waterway
2. is much shorter, but depending on river conditions, the Delta Mariner can be too big to fit.
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#505
by
kcrick
on 30 Jan, 2012 15:57
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Not sure if this is the proper thread and forgive me if it's been answered already (I've done some digging here and didn't find an answer), but I'm curious - what route does the Delta Mariner take from Decatur, AL. to the Cape to deliver rocket stages, etc. ?
Two ways to go
1. Tennessee river - Ohio river - Mississippi
2. Tennessee river - Tennessee–Tombigbee waterway
2. is much shorter, but depending on river conditions, the Delta Mariner can be too big to fit.
Ok, thanks. That helps. I was trying to follow the route from Decatur to Kentucky Lake where it struck the bridge. Curious though that it looks like there's a couple of dams along the route.
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#506
by
DMeader
on 30 Jan, 2012 17:23
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Curious though that it looks like there's a couple of dams along the route.
With locks, I assume?
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#507
by
kcrick
on 30 Jan, 2012 17:50
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Curious though that it looks like there's a couple of dams along the route.
With locks, I assume?
Yep, thanks. I took a closer look at the Kentucky Dam thru google earth and I see it.
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#508
by
robert_d
on 30 Jan, 2012 22:58
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1) Would a notional Delta 4 heavy with a SSME or RS_25e core engine instead of the actual RS-68 increase or reduce payload? Assume the two outboard boosters would still be RS-68 powered. Seems the trade would be higher ISP and slightly lower weight (lighter engine but added apu's) vs the gravity loss of the longer burn time. Any other considerations?
2) What would the payload effect be of adding a second RS-68 to the outboard boosters of a Delta 4 heavy? Burn duration would obviously be reduced by half (to about 210 seconds, remakably similar to the STS SRB's). From what I can tell the current 2 booster configuration is underpowered, but would this be ovekill or just overly expensive?
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#509
by
Antares
on 31 Jan, 2012 01:12
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Not enough real estate for a 2nd -68, but given the PWR cost increases with the demise of the NASA SSME contract, I opined that ULA/PWR should study a dual SSME CBC. I like your idea of an SSME center CBC too. Thinking about it, though, the decrease in liftoff T/W might be a killer. You'd have to offload a lot of propellant.
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#510
by
edkyle99
on 02 Feb, 2012 21:39
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1) Would a notional Delta 4 heavy with a SSME or RS_25e core engine instead of the actual RS-68 increase or reduce payload? Assume the two outboard boosters would still be RS-68 powered. Seems the trade would be higher ISP and slightly lower weight (lighter engine but added apu's) vs the gravity loss of the longer burn time. Any other considerations?
I modeled this, in a crude way, and found that payload to LEO would likely decrease by about 1 tonne, give or take (about a 3.5-4% performance reduction) and by about 0.5 tonnes to GTO (about 5% reduction). About 88 tonnes of propellant would have to be offloaded from the boosters (combined total) to maintain the 1.2 liftoff T/W ratio. That's about 21.5% of the propellant capacity for each booster. The core's better specific impulse would make up much, but not all, of the difference.
- Ed Kyle
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#511
by
Robotbeat
on 02 Feb, 2012 22:09
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1) Would a notional Delta 4 heavy with a SSME or RS_25e core engine instead of the actual RS-68 increase or reduce payload? Assume the two outboard boosters would still be RS-68 powered. Seems the trade would be higher ISP and slightly lower weight (lighter engine but added apu's) vs the gravity loss of the longer burn time. Any other considerations?
I modeled this, in a crude way, and found that payload to LEO would likely decrease by about 1 tonne, give or take (about a 3.5-4% performance reduction) and by about 0.5 tonnes to GTO (about 5% reduction). About 88 tonnes of propellant would have to be offloaded from the boosters (combined total) to maintain the 1.2 liftoff T/W ratio. That's about 21.5% of the propellant capacity for each booster. The core's better specific impulse would make up much, but not all, of the difference.
- Ed Kyle
A Delta IV Medium+ (5,4) with a Shuttle SSME for the core in place of the RS-68 would still maintain a much higher than 1.2 liftoff T/W so wouldn't need prop-unloading (which, no surprise, reduces performance).
Adding an SSME to the core would probably make the most sense (as far as maximizing payload) in the case of the variants of Delta IV Heavy proposed with extra GEMs. It would provide a lot of the benefit of cross-feeding since the SSME has a lot less thrust compared to RS-68. Adding two GEM60s to a Delta IV Heavy (with SSME core) should be plenty so no propellant unloading would be required.
It's all academic, anyway, since I supremely doubt the SSME in any variant (expendable or no) will get anywhere near as cheap as RS-68 while maintaining the same performance as the SSME currently has. Plus you have all the re-design necessary to make this worthwhile. It may well be that finishing Atlas V Heavy (and possibly even finishing wide body Centaur) would be cheaper than switching Delta IV to use partly SSMEs.
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#512
by
edkyle99
on 03 Feb, 2012 14:45
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It's all academic, anyway,
Agreed!
It may well be that finishing Atlas V Heavy (and possibly even finishing wide body Centaur) would be cheaper than switching Delta IV to use partly SSMEs.
Another cheaper alternative might be to steadily improve RS-68 performance over time.
- Ed Kyle
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#513
by
baldusi
on 03 Feb, 2012 15:13
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Adding an RS-25 doesn't help the rest of the fleet. But let's consider the other alternatives:
AlLi: lowers the structural weight. Can be done for both the core and the US. You could get a benefit to the whole fleet. Relatively simple change, but I ignore if it would need new tooling.
Fuel Densification: Improves your mass fraction. Gives benefit to the whole fleet. Could improve a lot the results of a regen RS-68. Would need new GSE.
Regen Nozzle RS-68: Would improve the T/W of the engine, allow for more thermal environment. Might even allow for thrust of isp improvements. Again, improves the whole fleet. Probably expensive.
Better US: This is sort of needed for many reasons, would lower the costs for ULA, improve performance and give better capabilities. Improves the whole fleet. Expensive.
Solids for the Heavy: improves the payload for very little cost. Only applies to Heavy. Cheap, might require minimum pad changes.
Cross feeding: improves the payload, probably more to the higher orbits than to LEO. Applies only to Heavy. Might require minimum pad changes.
With all this things applied, you could probably go close to 55ton to 60 ton to LEO. But the really interesting part is the GSO performance. It could be as high as 16tonnes. Please note, that's GSO, not GTO.
GTO would be close to 30tonnes. That's 166% of Falcon Heavy's performance. You've gotta love H2 vehicles for high energy orbits.
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#514
by
Antares
on 03 Feb, 2012 22:49
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Fuel densification changes loads. It would move the loaded mixture ratio toward rich, which would lower thrust. You'd have to densify LOX too, which would be an even bigger hit on loads. Loads increases increase weight due to stronger structure needed. Plus, the hit on T/W.
The rest are DOA too for the listed reasons.
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#515
by
Robotbeat
on 03 Feb, 2012 23:37
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Fuel densification changes loads. It would move the loaded mixture ratio toward rich, which would lower thrust. You'd have to densify LOX too, which would be an even bigger hit on loads. Loads increases increase weight due to stronger structure needed. Plus, the hit on T/W.
The rest are DOA too for the listed reasons.
Sad about the Better Upper Stage, though. That would be quite handy even for Atlas V launches (and could also benefit missions launched on SLS, since iCPS would likely be based off of the Delta IV upper stage).
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#516
by
baldusi
on 06 Feb, 2012 14:54
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Fuel densification changes loads. It would move the loaded mixture ratio toward rich, which would lower thrust. You'd have to densify LOX too, which would be an even bigger hit on loads. Loads increases increase weight due to stronger structure needed. Plus, the hit on T/W.
The rest are DOA too for the listed reasons.
Couldn't you just shorten the tanks (I'm assuming both H2 and LOX densification). With the just understanding that you'd have to re qualify, certify and change lot's of GSE/Pad attachments.
In any case I was pointing out that those are just as possible as putting dual SSME on the Delta IV core. And those were proposed by Boeing.
In any case I don't see a point of talking about "improvements" for a rocket that's barely flying due to a crime (i.e. if Boeing hadn't stolen the bidding numbers of LM the Heavy would have been Atlas V and it would all have been a very different story).
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#517
by
edkyle99
on 06 Feb, 2012 19:37
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... if Boeing hadn't stolen the bidding numbers of LM the Heavy would have been Atlas V and it would all have been a very different story. ..
I'm not sure that's the way things happened. According to the following RAND report, for example,
http://www.rand.org/pubs/monographs/2006/RAND_MG503.pdfLockheed Martin did not defer Atlas V Heavy development until
after the 1998 EELV competition. It actually "gave back" two launches to Boeing at that time, "when Lockheed Martin decided not to develop an Atlas V heavy-lift vehicle or to build a West Coast launch facility" for Atlas V.
Regardless, Boeing was soon caught (it turned itself in, didn't it?), and severely penalized to the tune of $1 billion in immediate launch re-allocations back to Atlas V, a lawsuit by Lockheed Martin, and much lost good will at the Pentagon. Lockheed Martin was awarded money to build that West Coast pad, etc., but the company never saw a need to develop its own Heavy, because 551/552 could compete for much of that business.
- Ed Kyle
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#518
by
baldusi
on 06 Feb, 2012 19:58
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... if Boeing hadn't stolen the bidding numbers of LM the Heavy would have been Atlas V and it would all have been a very different story. ..
I'm not sure that's the way things happened. According to the following RAND report, for example,
http://www.rand.org/pubs/monographs/2006/RAND_MG503.pdf
Lockheed Martin did not defer Atlas V Heavy development until after the 1998 EELV competition. It actually "gave back" two launches to Boeing at that time, "when Lockheed Martin decided not to develop an Atlas V heavy-lift vehicle or to build a West Coast launch facility" for Atlas V.
I had understood that since Boeing had better pricing information they underbid Atlas enough to make the AH a non viable development. The fact that they got so close in performance with the 551 also helped, of course.
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#519
by
yinzer
on 06 Feb, 2012 22:07
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... if Boeing hadn't stolen the bidding numbers of LM the Heavy would have been Atlas V and it would all have been a very different story. ..
I'm not sure that's the way things happened. According to the following RAND report, for example,
http://www.rand.org/pubs/monographs/2006/RAND_MG503.pdf
Lockheed Martin did not defer Atlas V Heavy development until after the 1998 EELV competition. It actually "gave back" two launches to Boeing at that time, "when Lockheed Martin decided not to develop an Atlas V heavy-lift vehicle or to build a West Coast launch facility" for Atlas V.
Is there a contradiction here? Boeing used their stolen data to create their bid such that they won most of the West Coast and Heavy flights. The few that Lockheed did win weren't enough to justify actually building the West Coast pad or the Atlas V Heavy, so they decided not to.
By the time Boeing got caught, they'd made enough progress that giving those launches back to Lockheed was going to add a lot of cost and slip a lot of the schedule, so they stayed with Boeing. Of course, by then Boeing was losing money hand over fist on the Delta IV and was staring down the face of a huge lawsuit from Lockheed that they were certain to lose, so they threatened to pull out of the market unless they could form ULA.
And, here we are.