Aside from flaming hunks of solid rocket booster burning holes in your parachutes and killing your astronauts, sounds great.
Quote from: JonathanD on 11/05/2018 08:07 pmAside from flaming hunks of solid rocket booster burning holes in your parachutes and killing your astronauts, sounds great.Doesn't seem to be a problem with escape systems on fighter jets carrying solid ordnance. And the SRBs stayed remarkably intact during Challenger when the liquid fuel tank exploded. OmegA is a four stage design including boosters, meaning each stage doesn't have to be built for minimal dry weight and maximum velocity contribution compared to 1/2/3 stage designs. The Shuttle SRBs being over-engineered vs the ET is why they stayed together and the ET didn't. So, one modification for man-rating would be making sure the new segments are as strong as the older steel casings even though there is no re-use.
So what things could you do to fix the solid-exhaust v/s parachute problem?1. Require a more powerful abort system, that can propel the spacecraft further from the vehicle.2. Require some sort of mechanism to extinguish the motors. *3. Set a rule that only spacecraft without parachutes, like Dreamchaser, can fly on Omega* Very difficult and expensive, but NASA engineers in the 70s thought it was possible
Quote from: JonathanD on 11/05/2018 08:07 pmAside from flaming hunks of solid rocket booster burning holes in your parachutes and killing your astronauts, sounds great.I mean SLS will have two giant SRBs for the first 2 minutes or so of its flight...Not saying OmegA is better, just a potential issue with SLS
Quote from: JEF_300 on 11/06/2018 02:16 amSo what things could you do to fix the solid-exhaust v/s parachute problem?1. Require a more powerful abort system, that can propel the spacecraft further from the vehicle.2. Require some sort of mechanism to extinguish the motors. *3. Set a rule that only spacecraft without parachutes, like Dreamchaser, can fly on Omega* Very difficult and expensive, but NASA engineers in the 70s thought it was possibleIt's not solid exhaust that's the issue. It's burning pieces of a solid boost that has blown itself apart that is the issue. So extinguishing the motor is not an option.Please see the video upthread of the 1997 Delta 2 explosion.
... Anyone designing a crewed system in my opinion would be nuts to fly on OmegA with its all solid first and second stage, when there are far safer alternatives that are or will be flying (Falcon 9, Falcon Heavy, Atlas V, Vulcan and New Glenn).
I agree. There's a reason I prefaced the title with "Thought Experiment"
Solids get a bad rap but they don't deserve it, if Challenger was scrubbed and didn't end up exploding solids would be viewed differently.
Oscillations are a problem, but far from insurmountable, the burning fuel flying everywhere is the big issue with a solid core stage. The LAS for Orion is capable of safely launching Orion away from an exploding SRB, and would work (obviously with some modifications) on OmegA. It was designed for Ares 1, and they haven't changed it for SLS. The other thing to consider would be launching Dreamchaser, SNC still wants to fly crew on it, they could launch the cargo version on OmegA first, and it doesn't have a LAS so they're probably screwed if the rocket blows up in such a manner anyway. Solid motor hate is far to prevalent
BTW an independent safety assessment made by (IIRC) McDonald Douglas during Shuttle design reckoned if anything would go wrong, it was in the SRB segment joints. Which is exactly where it did go wrong.
when there are far safer alternatives that are or will be flying (Falcon 9, Falcon Heavy, Atlas V, Vulcan and New Glenn).
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.
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.
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...)
In the unlikely scenario that Congress kept funding Orion after cancelling SLS, OmegA could be an option for Orion.
Quote from: ncb1397 on 11/06/2018 05:26 pmQuote 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.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.
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 field2) Extensive testing of vibrations/oscillations due to complete reliance on solid rocket motors in initial stages and potential redesign of upper stage with additional dampening3) 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.
Quote from: RonM on 11/06/2018 08:01 pmIn 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.
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...
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?
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.
Quote from: groundbound on 11/07/2018 09:01 pmOne 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.
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.
… 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.
...If Northrop Grumman is winning LSA money, they surely must be meeting some requirements for cost and safety.
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.
Quote from: Coastal Ron on 11/09/2018 03:20 amI 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.Quote… 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?QuoteHigher 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.
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.
3.0 ProgrammaticsThe following activities shall be conducted to allow the Government to gain insight and understanding of the development effort:...3. Business case analysis or updates to previously submitted business case analysis that examines the commercial competitiveness of the launch system under development against projected market conditions.
"“These awards are central to the Air Force goal of two domestic, commercially viable launch providers that meet National Security Space requirements,” said Lt. Gen. John Thompson, the Air Force’s Program Executive Officer for Space and SMC commander."
... comically unsafe. …
Quote from: brickmack on 11/10/2018 05:49 pm... comically unsafe. …People keep saying this as if it were true. The solids=unsafe assumption is largely based on one failed launch 32 years ago that would have been survivable if the crew of that flight had a launch escape system.
What about more of a direct Ares I clone? Castor 1200 plus a single large liquid second stage powered by BE-3Us. If you could do it with only 2 stages, 1 liquid, that'd be at least a bit less comically unsafe. Ares I's vibration issues were from the unfortunately matched frequency of the booster and the large upper stage. Composite booster structures might change that, and the upper stage could be proportionally smaller (both because of the much higher performance booster (lower dry mass, higher fueled mass, higher ISP) and the likely higher ISP of BE-3U than J-2X)
Quote from: brickmack on 11/10/2018 05:49 pm... comically unsafe. …People keep saying this as if it were true. The solids=unsafe assumption is largely based on one failed launch 32 years ago that would have been survivable if the crew of that flight had a launch escape system. - Ed Kyle
Quote from: edkyle99 on 11/10/2018 07:41 pmQuote from: brickmack on 11/10/2018 05:49 pm... comically unsafe. …People keep saying this as if it were true. The solids=unsafe assumption is largely based on one failed launch 32 years ago that would have been survivable if the crew of that flight had a launch escape system. - Ed KyleI disagree. I find the Delta II incident in 1997 a much more concerning situation. In the Challenger disaster, the SRBs did not explode until the range triggered the charges. In the Delta II '97 situation, IIRC it was a casing failure which resulted in the spectacularly bad hailstorm of flaming solid rocket motor debris. Hopefully a launch escape system could clear that aerial minefield, but it's a dramatically different scenario than a conflagration of liquid fuel.
Quote from: JonathanD on 11/11/2018 04:00 amQuote from: edkyle99 on 11/10/2018 07:41 pmQuote from: brickmack on 11/10/2018 05:49 pm... comically unsafe. …People keep saying this as if it were true. The solids=unsafe assumption is largely based on one failed launch 32 years ago that would have been survivable if the crew of that flight had a launch escape system. - Ed KyleI disagree. I find the Delta II incident in 1997 a much more concerning situation. In the Challenger disaster, the SRBs did not explode until the range triggered the charges. In the Delta II '97 situation, IIRC it was a casing failure which resulted in the spectacularly bad hailstorm of flaming solid rocket motor debris. Hopefully a launch escape system could clear that aerial minefield, but it's a dramatically different scenario than a conflagration of liquid fuel.From https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000094557.pdf(My underlines.)"1. Delta II Explosion EventThe Delta II rocket was launched from Launch Complex 17 (LC-17) at CCAFS at 1628 UTC on 17 January 1997. It exploded 12.5 seconds after liftoff at a height of approximately 438 meters. Figure 1 shows a photograph of the explosion. This initial explosion destroyed only the first stage and the boosters and produced a large cloud extending from the ground upward. The Delta II is a three-stage liquid-propellant vehicle with nine solid-propellant strap-on booster motors. The second and third stages and payload survived the initial explosion and continued upward to about 760 meters at 22.4 seconds. Destruct signals were sent at this point, and the exploding second-stage formed a buoyant cloud that …."The payload actually remained largely intact until it impacted the ground, causing the satellite propellants to explode and the Star motor to blast a big crater in the ground. The spectacular first big explosion was mostly the result of the automatic abort system detecting the failing SRM and, as a result, automatically destroying the boosters and first stage. (It should have destroyed the entire vehicle, but that's another story...) The still-intact upper stages and payload with fairing are clearly visible in this video at about the 1:38 mark. - Ed Kyle
Payload fairings and pressure-fed stages are reasonably robust (see: AMOS-6). Nylon parachutes are not. That the payload, Delta K 2nd stage, and STAR-48 survived the Delta II failure doesn't mean much for crew.The LES on a large solid LV needs to clear a ~3-mile diameter volume that is moving in roughly the same direction and speed as the launch vehicle before it disintegrated.