This idea popped into my brain and now I need answers. If, for whatever reason, it was decided in the next few years to attempt to man-rate Omega, what would that look like? How well suited is Omega to lofting crews? What would be the major roadblocks? How might these roadblocks be solved? Edited to add note: Try to think like an engineer, not a critic. This thread is NOT about whether or not Omega should be man-rated. It's is a mental an engineering challenge to figure out what would be required to man-rate it.
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. It seems like liquid propulsion gets put in the safe category by default in your list and solids go the other way.
even though it was the explosion of the ET (caused by the SRB), not the SRBs directly that caused Challenger to break up.
I would have thought that solids don't literally explode, and thus might cause less of an issue for aborts than liquid fuelled rockets. Wouldn't shrapnel from a RUD be more likely to hit a top-of-stack crew vehicle from a liquid-fuelled failure? Is there some other issue with failure modes in solids?
The answer is a LAS. There is no solid-exhaust vs parachute problem because the LAS moves the crewed vehicle to a safe distance before deploying the parachutes.For example, Orion on SLS.
Quote from: Steven Pietrobon on 11/06/2018 05:28 amwhen 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.
when there are far safer alternatives that are or will be flying (Falcon 9, Falcon Heavy, Atlas V, Vulcan and New Glenn).
It seems like liquid propulsion gets put in the safe category by default in your list and solids go the other way even though it was the explosion of the ET (caused by the SRB), not the SRBs directly that caused Challenger to break up.
Quote from: ncb1397 on 11/06/2018 01:06 pmQuote from: Steven Pietrobon on 11/06/2018 05:28 amwhen 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 OmegA crewed vehicle would be one long black zone that would give the Commercial Crew safety bureaucrats apoplexy.
Quote from: MattMason on 11/06/2018 05:12 pmAn OmegA crewed vehicle would be one long black zone that would give the Commercial Crew safety bureaucrats apoplexy.Not with a properly designed escape system. - Ed Kyle
Quote from: edkyle99 on 11/06/2018 05:34 pmQuote from: MattMason on 11/06/2018 05:12 pmAn OmegA crewed vehicle would be one long black zone that would give the Commercial Crew safety bureaucrats apoplexy.Not with a properly designed escape system. - Ed KyleWorse comes to worse, if you were super worried about this, it would require a 4 second abort motor accelerating the capsule to ~850 ft/s vs 3 seconds and 650 ft/s currently. That gives you much more margin over the speed and trajectory of SRB debris. But the current system it seems is designed to essentially get above the debris and then deploy parachutes, thus lowering the ballistic coefficient way below any debris (i.e. the debris falls quicker than the capsule). There is only raining down of SRB fragments if the fragments are above the capsule at parachute deployment. If that was the case, you are in the debris field already.
Like Ed said, you need a properly designed abort system. It could be done.
Quote from: Lars-J on 11/06/2018 05:02 pmQuote from: ncb1397 on 11/06/2018 01:06 pmQuote from: Steven Pietrobon on 11/06/2018 05:28 amwhen 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.
Quote from: RonM on 11/06/2018 05:07 amThe answer is a LAS. There is no solid-exhaust vs parachute problem because the LAS moves the crewed vehicle to a safe distance before deploying the parachutes.For example, Orion on SLS.That's a large assumption. Not to get conspiratorial, but one wonders if a contributing factor to the lack of an in-flight abort test for commercial crew being a requirement is reluctance to see a negative test result that could be tied to the use of the solids that NASA knew would be strapped to the side of the Atlas V. Such a test result could result in further scrutiny of the SLS architecture, for which they certainly are not going to do an in-flight abort test. That SpaceX is electing to perform one voluntarily is an interesting spice in the stew.
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 marker decide...
I'm still curious about whether the lack of parachutes on Dreamchaser makes it an option. Does anyone have information on Dreamchaser aborts?There's more to man-rating a vehicle than a good LES. For instance, while Ares I and Omega have some obvious similarities, I imagine they're G-force plots would look very different. How high will the G's go on an Omega launch? I would assume the extra staging will translate to lower G's, but perhaps it's counter-intuitive.