DIRECT v3.0 - Thread 1

[93143]

I've had the impression that they actually meant blowing the entire nozzle off (including the throat, of course), which would do a much better job of uncorking the beastie ...

That's right; the idea is to remove the entire nozzle.  There have been comments to the effect that this eliminates most of the thrust, so I thought it would be a good preliminary to the unzip, taking the time pressure off by preventing the boosters from chasing the capsule.

There are three potential concerns I see right now.  1) Requalification.  You can't fly the current SRBs any more because they don't have this feature.  2) Weight.  Ares I can't use it.  Kinda beside the point, as this is far from the only reason to go Direct instead.  3) The unzip itself.  Does it work as well if the nozzle is off?  How small do the pieces get?  How small do they need to be?

I suspect that would make matters worse, to be honest. The SRM nozzle is a partially submerged design. I would wager that, unless you're planning on severing the case, you'd have a good chance of plugging the whole thing...until it ruptured that is.

This is not a new idea.  I had the impression that it had been either done before or at least looked at...  What's wrong with severing the case?

Besides, even if you have to blow it at or below the throat, it would still reduce thrust significantly.  The point here is not so much to make the destruct more benign as to make it happen farther away from the Orion.

[kraisee]

To add to Lobo's question, is the core strength the same whether it's just a 130 payload or a 24x 2nd stage and payload? Does it have to be reinforced?

The Core Stage is designed one time, to handle the worst case loads for both flight options.   In practice the loads for the much bigger, heavier and more powerful Jupiter-24x tend to be the determining factor.

Design once, build once, fly in either configuration.

Ross.

[Bill White]

Thanks, Ross

I am primarily interested in acquiring a general understanding of the problem at a technical level suitable for a Congressional staffer.

And to acquire a low level understanding as to whether this could be a total "show stopper" for SDLV as a crew launch vehicle, in anticipation that the EELV-only guys will trot out this argument.

My understanding is that the current Ares 1 LAS is insufficient to allow the Orion capsule escape the debris cloud "column" prior to opening the parachutes and there is no margin to upgrade to a larger motor. Failure to escape the debris column will result in melted parachutes.

This leads to a question about whether the Jupiter 130 has sufficient margin to enhance the LAS motors sufficiently to allow the Orion capsule to escape the debris cloud column before parachutes are opened.

If I understand correctly, a steerable LAS sustainer motor could help fly Orion out of that debris column before opening the parachutes but would the mass penalties and technical challenges of that be prohibitive?

[Danny Dot]

I've had the impression that they actually meant blowing the entire nozzle off (including the throat, of course), which would do a much better job of uncorking the beastie ...

I suspect that would make matters worse, to be honest. The SRM nozzle is a partially submerged design. I would wager that, unless you're planning on severing the case, you'd have a good chance of plugging the whole thing...until it ruptured that is.

Good idea.  That would work just fine I think.  We did exactly that for the AGM-130.  Lots of fire comes out the back, but very little long duration thrust.  You get about a 10 fold increase in thrust for a few milliseconds until the pressure drops.  The forces will certainly rip the SRB off the ET, but that is OK.

Danny Deger

[Lobo]

I had a thought.

Direct I think is suggesting using the D4H to fly Orion on ISS or LEo only missions, correct?  And then J-130 for LEO missions when you want a payload as well?

I'm just wondering if going with the Falcon 9 Heavy woudn't be better.  The reasons being:
1)  Likely be less expensive than a D4H.
2)  Will already be human rated, as the F9 will be carrying a crewed Dragon. 
3)  SpaceX Launch Complex 40 will already be set up for loading crews into capsules.

Yea, I know The F9 much less the F9H has yet to fly.  But since Orion won't be developed for some time, seems like they would likely have one up before Orion's even ready.

I mean, they'll already be sending crews to the ISS on the Dragon via COTS, so why not keep all the human flight in the same system?

What say you?

[kraisee]

Ross,

NASA are currently working on Altair, and they seem to be continuing with their projects whilst Augustine deliberates. Presumably they may then do the same until (if) WH/congress issue new orders.

Are they still working on Altair? How much will things be delayed if NASA keeps to the current (since Augustine was announced) course?

Martin,
   The work being done on Altair is still extremely rudimentary and is being done at "drop in the water" levels of funding right now.   Essentially they're currently trying to get a feel for the vehicle before getting into the design cycles and review process properly.

Ross.

[William Barton]

I had a thought.

Direct I think is suggesting using the D4H to fly Orion on ISS or LEo only missions, correct?  And then J-130 for LEO missions when you want a payload as well?

I'm just wondering if going with the Falcon 9 Heavy woudn't be better.  The reasons being:
1)  Likely be less expensive than a D4H.
2)  Will already be human rated, as the F9 will be carrying a crewed Dragon. 
3)  SpaceX Launch Complex 40 will already be set up for loading crews into capsules.

Yea, I know The F9 much less the F9H has yet to fly.  But since Orion won't be developed for some time, seems like they would likely have one up before Orion's even ready.

I mean, they'll already be sending crews to the ISS on the Dragon via COTS, so why not keep all the human flight in the same system?

What say you?

I think any number of people here will tell you, "Falcon 9 Heavy is not a given." What I think is, if COTS-D Falcon 9/Dragon works out, there'll be no point in Orion on EELV to ISS. Dragon can just do the US crew rotations, and Orion will only ride on Jupiter 130 when there's a cargo involved (assuming any of this comes to pass--Jupiter 130 is not a given either, and maybe even Orion isn't a given).

[NUAETIUS]

I had a thought.

Direct I think is suggesting using the D4H to fly Orion on ISS or LEo only missions, correct?  And then J-130 for LEO missions when you want a payload as well?

I'm just wondering if going with the Falcon 9 Heavy woudn't be better.  The reasons being:
1)  Likely be less expensive than a D4H.
2)  Will already be human rated, as the F9 will be carrying a crewed Dragon. 
3)  SpaceX Launch Complex 40 will already be set up for loading crews into capsules.

Yea, I know The F9 much less the F9H has yet to fly.  But since Orion won't be developed for some time, seems like they would likely have one up before Orion's even ready.

I mean, they'll already be sending crews to the ISS on the Dragon via COTS, so why not keep all the human flight in the same system?

What say you?

Off topic for this tread.  Search the forums, this has been suggested ad nauseumin other thread, bump one of those.  Crewed COTS has not been green flagged, and might never.

[StuffOfInterest]

Ross,

Out of curiosity, did you meet up with the person who gave the public comment at yesterday's session that was the equivalent of a DIRECT 3-minute presentation?  The guy deserves a 1st edition DIRECT lapel pin!  If not that, at least a handshake from DIRECT's most public face.

[Kaputnik]

ON the topic of blowing the SRB nozzle...
I thought this was SOP during recovery? The nozzle is blown before impact with the ocean, is it not? That means the hardware and procedures are already in place.

[strangequark]

This is not a new idea.  I had the impression that it had been either done before or at least looked at...  What's wrong with severing the case?

Besides, even if you have to blow it at or below the throat, it would still reduce thrust significantly.  The point here is not so much to make the destruct more benign as to make it happen farther away from the Orion.

I'm hypothesizing here, but I would be concerned about large transient moments on the vehicle if you severed the very aft portion of the case. I don't see how you would control the thrust vector on the SRM during the detachment process, and fear it could give you some very large, very random forces on the integrated stack. This is as opposed to unzipping the case, as that provides rapid depressurization of the motor. As far as blowing downstream of the throat, at best you'll cut the thrust in half, which still gives you 1+ Mlb in thrust. I guess you have a point though. Even if that's still a huge amount of thrust, if it buys you enough margin then it's worth it.

ON the topic of blowing the SRB nozzle...
I thought this was SOP during recovery? The nozzle is blown before impact with the ocean, is it not? That means the hardware and procedures are already in place.

The aft exit cone is blown during recovery, which is what I thought the discussion was initially about. The LSC is in place there. That will not depressurize the motor, since the LSC is well downstream of the throat, but will cut the thrust down. As mentioned above, if you're just trying to buy some margin there, then maybe it's worth doing.

[strangequark]

The forces will certainly rip the SRB off the ET, but that is OK.

Danny Deger

My concern would be if it didn't do that fast enough, and you ended up pointing in some direction you wished not to go. What are yours thoughts on that Danny, cuz I am definitely beyond my demense on that topic.

[kraisee]

Thanks, Ross

I am primarily interested in acquiring a general understanding of the problem at a technical level suitable for a Congressional staffer.

And to acquire a low level understanding as to whether this could be a total "show stopper" for SDLV as a crew launch vehicle, in anticipation that the EELV-only guys will trot out this argument.

My understanding is that the current Ares 1 LAS is insufficient to allow the Orion capsule escape the debris cloud "column" prior to opening the parachutes and there is no margin to upgrade to a larger motor. Failure to escape the debris column will result in melted parachutes.

This leads to a question about whether the Jupiter 130 has sufficient margin to enhance the LAS motors sufficiently to allow the Orion capsule to escape the debris cloud column before parachutes are opened.

If I understand correctly, a steerable LAS sustainer motor could help fly Orion out of that debris column before opening the parachutes but would the mass penalties and technical challenges of that be prohibitive?

Its definitely not a "show stopper" for all SDLV's.   The worst possible case situation is you will have to make the LAS much more powerful in order to get the crew far enough away.

Just using Danny's First-Order tool you can tell that a LAS with 500,000lb of thrust, burning for 6.5 seconds is more than capable of EASILY getting a 20,500lb Orion Crew Module away from any possible danger, even in the WORST possible cases.

Of course, such a LAS masses over 30,000lb so you would need a launch vehicle able to loft it.   And that is where the differences come between some SDLV launchers and others...

Ares-I simply does not have sufficient performance to allow its LAS mass to grow by some 15,000lb.   If that's required, it would be a complete "show-stopper" for that concept.

Both Jupiter-130 and Jupiter-24x, on the other hand, can quite easily accommodate that growth -- and even more besides, if ever required.

Jupiter-130 and Jupiter-24x are both, far more capable systems, than Ares-I will ever be.

Ross.


PS -- Talking with Danny and an ATK guy about this problem, an additional sustainer engine does not seem to be a good idea at all.   It seems far better to increase the capability of the main abort motor and to shape the grain in order to give you a 'sustainer' effect (high-thrust star pattern to start, lower thrust cylindrical burn towards the end).

[robertross]

It looks like we have a multi-facetted approach required for dealing with the SRB debris with a Jupiter, and some, most, or maybe all might require a trade study on. Of course, the more things that need to happen during an abort, the more things can go wrong.

1) LAS motor with sustainer** added
2) SRB nozzle & LSC release
3) Unzip SRB
4) Bigger LAS motor
5) Other possibilities

You do combinations of the above to find the best scenario for crew survivability.

Of course D4H has no solids, so doesn't have this problem; it only has politics to worry about (assuming Jupiter is chosen as the best path).

** edit: In reference to what Ross, just posted, this would be a new LAS motor with diferent characteristics.  Now this would eliminate the rest of the choices then, since it requires no additonal method to function & keeps LOC numbers high. Case closed.

[kraisee]

Okay, here's the "worst case" scenario I was just talking about and what I would term as the "simple brute force" solution to it -- essentially boiling down to replacing the current Abort Motor with this larger one.

There are probably more elegant ways to make it work than this, but I'm providing this simply to show that this *is* a solvable issue for Jupiter.   What's needed now is "refinement".

This simulates a LAS activation at Max-Q (T+48s) on a Jupiter-130 CLV flight heading for ISS.

Further, it assumes the Core Stage breaks up instantly and the SRB's are released to accelerate towards the Orion at maximum acceleration (4g) for a period of 3.0 seconds before destruction -- essentially meaning they are allowed to pick up the maximum possible velocity in the same direction as the Orion before being blown.

The debris distribution shows parts from 0.5ft diameter to 3.0ft diameter, which should cover the full range of likely burning materials and high momentum case debris as well.

This also uses the corrected 8.2ft radius for Orion.

And this optimizes the Drogue deploy time for this situation (which would be an automated function).

This models a 500,000lb thrust LAS, with no sustainer, massing 31,655lb -- roughly 35% greater thrust, roughly double the burn time and almost twice the mass of the current design (Note: The calculator currently doesn't model the SRB thrust curve of the motor accurately, but Danny is looking into that as an improvement for his spreadsheet).

It produces a 10G 'punch' for the Orion & Crew -- which is well within the 18G Crew safety limits and is broadly similar to the current punch of the existing LAS.

Ross.

[kraisee]

Well, we just hit the 250 page mark once again, so I am starting the "DIRECT v3.0 - Thread 2" thread here:

http://forum.nasaspaceflight.com/index.php?topic=18139.msg451519#msg451519

This thread will be locked now.

Ross.