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#40
by
freda
on 06 Nov, 2018 22:31
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Hmmm... interesting. A related curious thought pops into my mind, for discussion: Man-rating Ares solid booster verses man-rating the OmegA solid booster:
Are there differences to consider? Similarities?
For that matter, could the existing (Shuttle + SLS) SRB segment booster (already man-rated) replace the OmegA booster?
You can probably tell I am in no way an expert in this topic
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#41
by
john smith 19
on 06 Nov, 2018 22:32
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Every propellant has its own DDT (deflagration-detonation transition) conditions. The propellants used in SRBs are resistant to it, so it's not talked about much. (NASA must assume the likelihood of detonation-mode failure is zero to come up with the LOC numbers they use.) But DDT onset is accentuated by larger motor sizes, and they don't come much larger than the five-segment motors we're talking about. Even before Challenger, I sweated every shuttle launch until SRB sep. (worse afterwards...)
"Resistant" to DDT is not the same as impossible.
I found it interesting that the burn rate for these motors is around 0.34"/sec while those for the Sprint ABM (possibly the highest performing solid prop vehicle ever built) was more like 40"/sec (with experimental motors hitting more like 50"/sec. Unfortunately this seems to have often been just before they went to a full on explosion).
IIR NASA looked at ways to shut big solids down but concluded they'd tear the Shuttle stack apart with shock loads. Blowing the tail cone off and blowing holes in the top end of the pressure vessel seemed to be involved.
An interesting question would be do you want full shut down? Could lowering it's forward thrust, while blowing some of its exhaust out the front end (through inter stage blow out panels?) be good enough to separate a rogue stage or booster?
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#42
by
TomH
on 07 Nov, 2018 05:46
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In the unlikely scenario that Congress kept funding Orion after cancelling SLS, OmegA could be an option for Orion.
Falcon Heavy and New Glenn could as well, sans solids. And they are partly reusable.
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#43
by
Zed_Noir
on 07 Nov, 2018 10:41
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For launch abort. The Original Dragon 2 LES concept with superDracos with additional SuperDracos installed in the trunk might work on top of the OmegA after blowing out the seams of the Castor motors. Presuming that the SuperDracos is activated prior to unzipping the Castors.
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#44
by
envy887
on 07 Nov, 2018 15:41
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In the unlikely scenario that Congress kept funding Orion after cancelling SLS, OmegA could be an option for Orion.
To what end? Orion is a (not-too)deep-space vehicle. Omega is too small to lift it much beyond LEO. And unlike ULA with Vulcan ACES, NGIS has no plans to implement refueling which would allow Omega to send Orion to TLI or beyond.
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#45
by
JonathanD
on 07 Nov, 2018 16:45
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So to summarize the thought experiment of "what would be required to put crew on OmegA" :
1) Significantly enhanced LES in order to ensure safe clear of debris field
2) Extensive testing of vibrations/oscillations due to complete reliance on solid rocket motors in initial stages and potential redesign of upper stage with additional dampening
3) A spacecraft that is either developed specifically for OmegA or an existing spacecraft that is adapted, with some potential redesign work.
...and perhaps most importantly...
4) A reason to do it. With two commercial crew providers coming online plus Orion/SLS, it would be incredibly difficult to justify funding Steps 1-3 above.
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#46
by
Hog
on 07 Nov, 2018 17:27
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when there are far safer alternatives that are or will be flying (Falcon 9, Falcon Heavy, Atlas V, Vulcan and New Glenn).
The SRBs had one failure out of 270 SRBs flown. How is Falcon 9 with 2 upper stage failures in 62 flights safer? Atlas V is safe, but Vulcan and New Glenn? That is highly debateable.
Liquid engines and stages certainly can (and do) fail, but their failure modes are far generally more benign. And they can be turned off.
An example would be good. The "failure mode" of the 1998 Delta II was the activation of the flight termination system. It was designed to do that to the booster. In a manned system, the flight termination system won't be activated right away, which is why the Challenger SRBs didn't explode and kill the crew, the ET exploded and killed the crew. It was exactly the opposite of what you said, the SRBs failed, but they did so benignly as far as damaging the crew vehicle. There was no large SRB explosion that destroyed/damaged orbiter, there was a large liquid fuel explosion that did.
If Challenger had liquid boosters and the boosters did this:
The ET would have likely failed just the same. And as seen in the recent Soyuz failure, liquid boosters are also capable of impacting the core and destroying it, which is what the SRB on challenger did.
This is wrong in many ways. Challenger had no LES and was not destroyed by the ET conflagration (not an explosion), but was forced into a non-aerodynamic orientation and the airflow (well above Mach 1) ripped it apart. LRBs have no failure mode similar to the Challenger SRB failure mode (a combustion chamber or engine bell leak could not directly impinge on the ET or the attachment struts because the engines are below the ET and struts), but some other failure (similar to the Soyuz MS-10 failure) could cause a booster to collide with and rupture the ET. However, there would have been much more time to react. The boosters would be shut down before separation, not driving at full thrust through the ET, and like Soyuz, the SSMEs would have shut down and allowed an orderly separation of the orbiter, which would have either ditched or attempted an RTLS abort. Probably unsuccessfully, which is why an LES is good. (Close to liftoff, even with non-exploding but detached or out of control LRBs, the orbiter wouldn't be above its stall speed and would be doomed by any booster failure. LES is good!)
An SRB joint failure could just as easily cut into the orbiter as the ET, possibly destroying a wing or the tail or the heat shield or rupturing the LOX/LH2 fuel cell tanks, or the N2O2/Hydrazine OMS tanks, or the SRB blowtorch could have pointed the other way. (In that case the reduced, asymmetric thrust would have still caused an abort, but it might have been survivable.) Just because the SRBs didn't directly destroy the orbiter doesn't let them off the hook in any way.
A Dragon 2 (or any other crewed vehicle with an LES) would have survived the AMOS-6 failure.
With STS, once the SSME's have been shutdown, a Return To Launch Site abort is an impossibility. Their thrust is required for the Powered Pitch Around(PPA) maneuver(planned to be performed with 2% propellants in tank). The best case scenario would entail dropping the ET as quickly as possible and attempting to get the Orbiter into a glide for bailout. I'm not sure what would be possible so far as dropping an ET without purging the propellants or getting into a glide orientation without dumping any OMS propellants. Both of these activities are part of the RTLS abort.
Post Challenger the 2 and 3 engine out black zones were much reduced with the reinforced ET, Orbiter attach hardware.
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#47
by
envy887
on 07 Nov, 2018 18:13
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So to summarize the thought experiment of "what would be required to put crew on OmegA" :
1) Significantly enhanced LES in order to ensure safe clear of debris field
2) Extensive testing of vibrations/oscillations due to complete reliance on solid rocket motors in initial stages and potential redesign of upper stage with additional dampening
3) A spacecraft that is either developed specifically for OmegA or an existing spacecraft that is adapted, with some potential redesign work.
...and perhaps most importantly...
4) A reason to do it. With two commercial crew providers coming online plus Orion/SLS, it would be incredibly difficult to justify funding Steps 1-3 above.
Orion should meet 1-3 above, since SLS going sideways would generate an even worse debris cone than Omega.
Whether it actually does? I would love to see that study. I hope it exists.
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#48
by
JonathanD
on 07 Nov, 2018 18:25
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Orion should meet 1-3 above, since SLS going sideways would generate an even worse debris cone than Omega.
Whether it actually does? I would love to see that study. I hope it exists.
It's kind of a waste of Orion to put it on a rocket that's only going to get it to LEO. And I recall all the modifications they had to do to Ares 1-X to compensate for vibrations. SLS Core stage will help dampen things for SLS, but on OmegA there may be additional work done on the upper stage to account for that.
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#49
by
RonM
on 07 Nov, 2018 18:48
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In the unlikely scenario that Congress kept funding Orion after cancelling SLS, OmegA could be an option for Orion.
To what end? Orion is a (not-too)deep-space vehicle. Omega is too small to lift it much beyond LEO. And unlike ULA with Vulcan ACES, NGIS has no plans to implement refueling which would allow Omega to send Orion to TLI or beyond.
I'm thinking about what Congress might do, not what we think would be good ideas.
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#50
by
JEF_300
on 07 Nov, 2018 20:10
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Keeping mind that this is a bad idea; canceling SLS and flying Orion on Omega doesn't eliminate deep space as a destination, it just means that you need to use some sort of Earth Orbit Rendezvous architecture to get there.
If anyone knows anything about how well Omega's G levels and trajectory fit a manned spaceflight, I'm certainly curious. I know Boeing is buying the two engine centaur on CST-100 launches for a flatter trajectory, so how flat is Omega's trajectory?
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#51
by
groundbound
on 07 Nov, 2018 21:01
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There is simply NO need to manrate OmegA. There are plenty of 'manrated' boosters either in existence or about to be. End of story. I do think OmegA should be optimised to lift the biggest payloads possible as a cargo or satellite launcher. And if it succeeds or fails on it's own merits/drawbacks; let the market decide...
This. One of the riskiest things about regular old OmegA is that it might end up fatally cost-uncompetitive by the time it flies. Loading the costs of man-rating onto it makes that risk worse.
There are uncountable potential rocket designs that are technically feasible if you spend enough money but pointless to discuss because of the cost. I would not include OmegA in that pantheon, but that is not a "problem" that needs to be solved.
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#52
by
envy887
on 08 Nov, 2018 14:22
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Keeping mind that this is a bad idea; canceling SLS and flying Orion on Omega doesn't eliminate deep space as a destination, it just means that you need to use some sort of Earth Orbit Rendezvous architecture to get there.
If anyone knows anything about how well Omega's G levels and trajectory fit a manned spaceflight, I'm certainly curious. I know Boeing is buying the two engine centaur on CST-100 launches for a flatter trajectory, so how flat is Omega's trajectory?
Trajectory shouldn't be a problem. Solids produce lots of thrust and have short burn times, so it will get to the first two staging velocities quickly. The 3rd stage is a dual-engine RL-10 according to the marking artwork, so its trajectory should be comparable to DEC.
One of the few advantages of Ares-1 was its short and flat ascent trajectory.
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#53
by
edkyle99
on 09 Nov, 2018 02:36
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One of the riskiest things about regular old OmegA is that it might end up fatally cost-uncompetitive by the time it flies. Loading the costs of man-rating onto it makes that risk worse.
Omega won one of the most recent three EELV-2 contracts, so it wasn't uncompetitive in that race. Vulcan Centaur uses three different propellant combinations and propulsion contractors compared to two for Omega (one of them in-house), so it should be able to compete on that basis. New Glenn is a giant, weighing nearly 1,400 tonnes even for the smallest payloads, compared to 440 tonnes for Omega 500 (Medium), so there is potential to compete even when New Glenn recovers its first stage.
- Ed Kyle
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#54
by
Coastal Ron
on 09 Nov, 2018 03:20
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One of the riskiest things about regular old OmegA is that it might end up fatally cost-uncompetitive by the time it flies. Loading the costs of man-rating onto it makes that risk worse.
Omega won one of the most recent three EELV-2 contracts, so it wasn't uncompetitive in that race.
I don't think you understood the question, since the USAF contract was not intended to find low-cost launch providers (or high cost ones for that matter), it was to find qualified launch providers. It's not up to the government to ensure the bidders have the financial wherewithal to find a foothold in the future launch market.
Vulcan Centaur uses three different propellant combinations and propulsion contractors compared to two for Omega (one of them in-house), so it should be able to compete on that basis. New Glenn is a giant, weighing nearly 1,400 tonnes even for the smallest payloads, compared to 440 tonnes for Omega 500 (Medium), so there is potential to compete even when New Glenn recovers its first stage.
None of that is related to operational costs.
Not only that, regardless how much New Glenn costs Jeff Bezos has the financial ability to support Blue Origin forever, meaning that they can charge normal prices for government contracts (GAO rules demand accurate pricing), but sell commercial launches at cost to essentially buy market share. In such a case both ULA and NGIS would have a harder time gaining any commercial contracts in order to spread their operational costs across more launches.
Higher cost, along with questionable safety, would make OmegA an unlikely choice for human-rating - for any customer.
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#55
by
edkyle99
on 09 Nov, 2018 14:40
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I don't think you understood the question, since the USAF contract was not intended to find low-cost launch providers (or high cost ones for that matter), it was to find qualified launch providers. It's not up to the government to ensure the bidders have the financial wherewithal to find a foothold in the future launch market.
The intent of EELV-2 (soon to be renamed NSSLP) is to enable "commercially viable" launch services that can also meet USAF/NRO/etc. launch requirements. If it isn't commercially viable, it isn't going to win. Omega won an LSA, so it is still in the game.
… regardless how much New Glenn costs Jeff Bezos has the financial ability to support Blue Origin forever, meaning that they can charge normal prices for government contracts (GAO rules demand accurate pricing), but sell commercial launches at cost to essentially buy market share. In such a case both ULA and NGIS would have a harder time gaining any commercial contracts in order to spread their operational costs across more launches.
The US should base its national defense strategy on the idea that one guy will bankroll his program forever?
Higher cost, along with questionable safety, would make OmegA an unlikely choice for human-rating - for any customer.
You keep saying that Omega has higher costs and questionable safety. Why? What is your basis for those assertions? If Northrop Grumman is winning LSA money, they surely must be meeting some requirements for cost and safety.
- Ed Kyle
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#56
by
M129K
on 09 Nov, 2018 17:19
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I'm wondering: do we actually have LEO payload figures for Omega? I haven't been able to find any so far. It's great and all if it might hypothetically be used to launch Orion, but if it can't get the ~27 tonne capsule with its heavy LES into LEO the discussion becomes pretty moot.
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#57
by
envy887
on 09 Nov, 2018 22:47
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...If Northrop Grumman is winning LSA money, they surely must be meeting some requirements for cost and safety.
Safety of a crew capsule during or after a launch failure is certainly not a USAF requirement for EELV.
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#58
by
envy887
on 09 Nov, 2018 22:48
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I'm wondering: do we actually have LEO payload figures for Omega? I haven't been able to find any so far. It's great and all if it might hypothetically be used to launch Orion, but if it can't get the ~27 tonne capsule with its heavy LES into LEO the discussion becomes pretty moot.
I'm pretty sure they would need the XL version with several solid strap-on to get Orion the LEO. The Delta IV Heavy is iffy for Orion to LEO, and the XL has similar performance to DIVH.
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#59
by
ChrisWilson68
on 09 Nov, 2018 22:57
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I don't think you understood the question, since the USAF contract was not intended to find low-cost launch providers (or high cost ones for that matter), it was to find qualified launch providers. It's not up to the government to ensure the bidders have the financial wherewithal to find a foothold in the future launch market.
The intent of EELV-2 (soon to be renamed NSSLP) is to enable "commercially viable" launch services that can also meet USAF/NRO/etc. launch requirements. If it isn't commercially viable, it isn't going to win. Omega won an LSA, so it is still in the game.
… regardless how much New Glenn costs Jeff Bezos has the financial ability to support Blue Origin forever, meaning that they can charge normal prices for government contracts (GAO rules demand accurate pricing), but sell commercial launches at cost to essentially buy market share. In such a case both ULA and NGIS would have a harder time gaining any commercial contracts in order to spread their operational costs across more launches.
The US should base its national defense strategy on the idea that one guy will bankroll his program forever?
Higher cost, along with questionable safety, would make OmegA an unlikely choice for human-rating - for any customer.
You keep saying that Omega has higher costs and questionable safety. Why? What is your basis for those assertions? If Northrop Grumman is winning LSA money, they surely must be meeting some requirements for cost and safety.
There's no evidence the Air Force did, or had any intent to, any sort of evaluation of eventual commercial viability, at this early stage.
Indeed, the evidence strongly suggests that they ignored cost and gave money to every company that had a launch vehicle similar to what the Air Force expects from an EELV. The only company that didn't get money was SpaceX, but that's because their vehicles that are in the EELV class (Falcon 9 and Falcon Heavy) are already in production use and don't need any more development money. BFR isn't what the Air Force was asking for, it's a very different vehicle.
When everyone who had a vehicle like what the Air Force asked for on offer got money, it's really a case that there were no losers. If there are no losers, winning doesn't mean very much. And it certainly doesn't mean that Omega will be cost-competitive.
