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NASA SLS/Orion/Payloads

_Augustus_

By _Augustus_
in Science & Spaceflight

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mikegarrison

mikegarrison

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I've got no dispute that the overall Orion project is a huge waste of money. It's a launcher in search of a reason to launch, ordered by an agency that needs a launcher in order to justify their continued existence, approved by a Congress who cares more about whether the money spent will result in votes than whether it will buy anything useful.

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tater

tater

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14 minutes ago, mikegarrison said:

I've got no dispute that the overall Orion project is a huge waste of money. It's a launcher in search of a reason to launch, ordered by an agency that needs a launcher in order to justify their continued existence, approved by a Congress who cares more about whether the money spent will result in votes than whether it will buy anything useful.

Seems like for huge, expensive projects like this, there needs to be as a first step, a very well defined goal. A SHLV for its own sake makes little sense, particularly if the annual program costs and possible launch cadence are such that launches literally cost from 2-4 B$ each, since the payload then needs to be commensurately expensive to justify the launch, etc, ad nauseum.

Back when SLS started, they talked about having "capability" more than a specific mission. Having broad capabilities is awesome, but since this is the real world, and money matters, that capability needs to be cheap if it's going to create a market for that capability. We have yet to see huge cost reductions (though since SpaceX we've seen a nontrivial amount), and there won't be until there is reason for SpaceX or Blue Origin to start competing over price, but I can see it coming down in the future, which I think will be quite enabling. Imagine when NASA doesn't have to blow 2-4 B$/yr on program costs for a SHLV, and can spend that money on payloads they can launch for what programs like SLS spend on coffee.

 

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XB-70A

XB-70A

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13 minutes ago, SuperFastJellyfish said:

SRBs never disappoint.  :) 

Could not agree more! :D  Can't wait for Atlas V 551 to end its 8 months long rest in two weeks.

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ZooNamedGames

ZooNamedGames

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27 minutes ago, tater said:

Well, except the one time that leaps to mind :(

 

To be fair, and as @SuperFastJellyfish mentioned, that was launching outside of safe conditions and even after a short spurt of burning fuel out of the side, both motors continued to operate nominally. Both having to be detonated by the RSO. The fact both survived despite an entire vehicle literally exploding beside them, is incredible.

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KSK

KSK

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15 hours ago, ZooNamedGames said:

To be fair, and as @SuperFastJellyfish mentioned, that was launching outside of safe conditions and even after a short spurt of burning fuel out of the side, both motors continued to operate nominally. Both having to be detonated by the RSO. The fact both survived despite an entire vehicle literally exploding beside them, is incredible.

Not really. They're damn great steel tubes designed to contain a rather substantial controlled explosion. It would have been more surprising (and alarming) if they hadn't survived.

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ZooNamedGames

ZooNamedGames

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8 hours ago, KSK said:

Not really. They're damn great steel tubes designed to contain a rather substantial controlled explosion. It would have been more surprising (and alarming) if they hadn't survived.

Perhaps but they are more advanced than a 'tube-o-boom'. With gimballing nozzles to direct their thrust and throttle- not to mention the fuel that they contain burns hotter than the temperature than the melting point for the metal container. All it would've taken was a ding to the right part of the tube and the whole thing would go up. Not to mention if the gimbal wasn't properly aligned or kept on the correct course (perhaps damage from the resulting shockwave) it could've spun off course, ended up in a spin or a myriad of other outcomes.

I get your point KSK. Solid rocket motors are simple, no fuel pumps, cooling systems or anything else- but to be fair, the space shuttle SRMs were some of the most advanced that I'm aware of, that still remain in operation. Perhaps I'm not informed though and I eagerly await seeing a more advanced booster.

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KSK

KSK

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Oh, they were far more than a tube o' boom - their ignition system was particularly impressive. Heck, it would have been impressive for one booster but lighting two closely enough together that the shuttle went straight up... yeah.

There was a lot to admire about them but I don't believe they were quite as potentially fragile as you're making them out to be.

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ZooNamedGames

ZooNamedGames

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10 hours ago, KSK said:

Oh, they were far more than a tube o' boom - their ignition system was particularly impressive. Heck, it would have been impressive for one booster but lighting two closely enough together that the shuttle went straight up... yeah.

There was a lot to admire about them but I don't believe they were quite as potentially fragile as you're making them out to be.

Perhaps you're right. I just don't find anything about a vehicle disintegrating in one of the most violent ways we've ever seen in manned spaceflight to be something boosters designed to handle (in normal configurations) merely aerodynamic stresses, some friction heating and the comparatively light staging process to be of the same scale.

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KSK

KSK

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47 minutes ago, ZooNamedGames said:

Perhaps you're right. I just don't find anything about a vehicle disintegrating in one of the most violent ways we've ever seen in manned spaceflight to be something boosters designed to handle (in normal configurations) merely aerodynamic stresses, some friction heating and the comparatively light staging process to be of the same scale.

I'm quite possibly not right but I do think you're lowballing this a bit for a couple of reasons:

1.  SRB combustion is a lot more violent than that of a liquid fueled engine - those things vibrate a lot in flight which, as you'll recall was a noted problem with the Ares 1X test flight - not for the booster itself but the proposed capsule on top. Also (again, as you'll know) an SRB is effectively a single, large combustion chamber and designed to be appropriately sturdy. So even operating within normal parameters, SRBs are designed to take quite a lot of punishment.

2. The Shuttle SRBs were big beasts - empty they were each about 91 tons of slightly less than half inch thick steel tube. That first number is taken from Wikipedia so treat with appropriate caution but the second is taken from a NASA document. Half an inch of steel can take quite a beating. For context, each fully fueled SRB weighs about 590 tons

3.  The Shuttle SRBs were designed to remain intact after a nozzle first splashdown. Okay, they were parachuting in but they were still hitting the water pretty hard - and the nozzle, gimbals etc. were presumably designed with that in mind.

4.  It's not a strictly apples for apples comparison, but I recall a SpaceX mission which ended pretty violently (CRS-7??) with a second stage RUD - which, from video footage, appeared to be survivable for the capsule parked on top. Obviously this is just suggestive - I can't make any meaningful comparison between the structural strength of a Dragon capsule vs that of a Shuttle SRB. Still - once you get away from as-light-as-possible liquid fuel tanks, it seems that other spacecraft components are more explosion proof than you might expect. For that matter (and a moment of silence here please), I recall that the Orbiter survived the explosion more-or-less intact but broke up afterwards due to aerodynamic stresses.

5.  A genuine question here - booster explosions look extremely violent but how much force is that explosion actually generating?

 

 

Edited by KSK
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