DIRECT v3.0 - Thread 1

[Danny Dot]

snip

Forgive my engineering ignorance, but is the same true for the MLAS? (or is that what you were referring to as the "LAS that weighs 22,600 pounds"?)

Jesse

I am not 100% sure I understand the question, but I think the answer is the MLAS does not have a sustainer.  I have made no effort to model this dog that probably can't be kept stable.

Danny Deger

[TrueBlueWitt]

Okay, let me try to demonstrate what I'm talking about.

That is, if this screen capture works or not...   Please let me know if you have problems reading this avi (XviD MPEG 4 format).

Ross.

No luck on work laptop(limited Video codecs).

Most likely I have a player on home system that will play it.

Did you try VLC player?

Works fine at home.. even in Windows media player.. It was just my video codec challenged Work laptop that had issues.  Installing unsanctioned software is severely frowned upon by the company... Although at least I could on my laptop.. My workstation is totally locked down in that regard.. We can't even hide the taskbar!

[Danny Dot]

I'm not sure if these options were asked/considered yet:

1) What about taking a performance hit on the SSME on ascent to reduce Direct's velocity? Just burn for longer. I say this to give an option if the schedule doesn't permit time to develop a new LAS (or add a sustainer). Once a new LAS is qualified & accepted, then this can be used with full performance from the stack.

On 1. I don't understand.  Please explain more detail so I can model the abort conditions.

Right now Direct (and of course shuttle) runs the SSME at 104.5% of thrust. What if we back it down to 98% (or whatever turns out best) of thrust during ascent?? I'm not sure what the cut-off point would be where you need a certain minimum thrust level, but since there is margin in the Jupiters, dive into some of it to solve the crew abort scenario.

I don't think this will help.  At some point you are going to go through the same velocities.  Reducing max q doesn't help a lot.  If you can crank some flight profile numbers, I can take a look at them.

Danny Deger

[TrueBlueWitt]

EDIT to add: And the SSME throttles down as it approaches Max Q as well, so if it stayed there, or throttled down even further while still keeping enough thrust, it could help in the critical phase(s).

Shuttle already throttles down at max Q(what is Shuttle's Max Q?)... so this shouldn't be a big deal.. Might have a minor impact on performance.  Someone would have to run those numbers.

[robertross]

I don't think this will help.  At some point you are going to go through the same velocities.  Reducing max q doesn't help a lot.  If you can crank some flight profile numbers, I can take a look at them.

Danny Deger

Ah yes, but for the entire, what 190 sec? of SRB burn??

Once you lose the SRBs, your problem with them goes away as well. So cut back the SSME thrust during the ascent profile with the SRBs, and when they separate, throttle up and burn the SSME engines longer to get to orbit.

That's what I'm thinking.

[robertross]

If you can crank some flight profile numbers, I can take a look at them.

Danny Deger

Whoa, that's WAY out of my department...LOL.

I can come up with crazy (kraisee? LOL) ideas, and sometimes some good remarks (at least I think so), but math & orbital mechanics??? Not happening...lol.

Paging MP99...   

[Danny Dot]

EDIT to add: And the SSME throttles down as it approaches Max Q as well, so if it stayed there, or throttled down even further while still keeping enough thrust, it could help in the critical phase(s).

Shuttle already throttles down at max Q(what is Shuttle's Max Q?)... so this shouldn't be a big deal.. Might have a minor impact on performance.  Someone would have to run those numbers.

About 742.21338738 psf.  Give or take a few significant digits.

Danny Deger

It is close to 740.  I have heard it was designed for 800, but operationaly is kept to about 740.

[Danny Dot]

I don't think this will help.  At some point you are going to go through the same velocities.  Reducing max q doesn't help a lot.  If you can crank some flight profile numbers, I can take a look at them.

Danny Deger

Ah yes, but for the entire, what 190 sec? of SRB burn??

Once you lose the SRBs, your problem with them goes away as well. So cut back the SSME thrust during the ascent profile with the SRBs, and when they separate, throttle up and burn the SSME engines longer to get to orbit.

That's what I'm thinking.

It would change the first stage profile.  But I have played with the model enough to know changes to flight profile parameters don't help a whole lot.  For example I have run 45 degree velocity vector angle (gamma) and 75 gamma.  It helped a little.  400 psf is better than 1200 psf, but even that low dynamic pressure does not solve the problem.  Do you have a copy of the model and Excel.  It is easy to do work with.  Play with abort conditions and see if you can come up with something that helps.  I have tried and failed.

Danny Deger

[Ronsmytheiii]

well you could always blow the core to push the boosters away, and there goes the baby.....

[ar-phanad]

snip

Forgive my engineering ignorance, but is the same true for the MLAS? (or is that what you were referring to as the "LAS that weighs 22,600 pounds"?)

Jesse

I am not 100% sure I understand the question, but I think the answer is the MLAS does not have a sustainer.  I have made no effort to model this dog that probably can't be kept stable.

Danny Deger

Sorry Danny, I meant to ask if the MLAS was equally doomed as the LAS. It does seem rather unwieldy, and I can't imagine that pitching it -15° under those conditions would leave any semblance of stability.

I guess I was just wondering if MLAS has a thrust advantage over the traditional LAS, and whether or not that would make a difference.

Jesse

[Danny Dot]

snip

Sorry Danny, I meant to ask if the MLAS was equally doomed as the LAS. It does seem rather unwieldy, and I can't imagine that pitching it -15° under those conditions would leave any semblance of stability.

I guess I was just wondering if MLAS has a thrust advantage over the traditional LAS, and whether or not that would make a difference.

Jesse

A far as I know it has the same thrust performance as the LAS. 

Danny Deger

[luke strawwalker]

Well, FUD goes this is probably the easiest to deflect... If NASA is now objecting to the idea of a backwards docking for the Altair but suggesting that a propellant transfer from one upperstage to the other serving EDS duty is a better option (for their proposal) then the same mission achitecture can still work perfectly fine-- One J-246 launches with the LSAM/CEV (or perhaps just the LSAM and the CEV rides up on the other rocket's upperstage, the one donating it's propellant to the EDS/LSAM stack waiting on orbit.  The two rendezvous and dock (berth?) and transfer the props, undock, manuever away from each other, the Orion discards the now empty stage, rendezvous and docks to the LSAM, and the stack is ready to proceed with TLI... 

Later!  OL JR

Even better, as was pointed out to me, would be to launch the J-246+CEV+LSAM fully fueled (instead of 56% offload).  Then launch the second J-246 with NO payload fully fueled (the EDS config).  However instead of being the EDS, the second JUS is just a tanker, and transfers all of its remaining fuel to top off the CEV+LSAM+EDS.  Thus, the LSAM never has to perform any docking in LEO, it remains attached to its launch EDS.  Only the CEV detaches and then docks with the LSAM.  This would give even better performance than the current DIRECT baseline.

Mark S.

That's basically what I was getting at... one 246 launches with the LSAM and Orion and achieves orbit with the tanks still half full.  The other 246 launches with a fully tanked upperstage with only a fairing over the docking target/fuel transfer connections.  It achieves orbit half full.  The Orion can dock with it, and the prop lines connected (if a head on docking is desirable, a side berthing and fuel transfer might be preferable, dunno, really don't care, it's the idea that counts) and the props transferred from the bare stage to the TLI stack, which can then seperate and perform TLI at their leisure.  In this scenario, Orion doesn't even have to seperate from the stack and dock to Altair in LEO; the stack can go through TLI just like Apollo did.  Of course if it's not a problem for the LIDS to handle eyeballs out TLI, disposing of the slot panels might increase mass thru TLI. 

THe other way could work nearly the same, Orion on one 246 which then sidles up to the Altair on the EDS in orbit, with half of the props remaining in both stages.  The Orion transfers the props in it's upperstage to the EDS/Altair stack, moves off, expends the empty stage, and docks with the Altair eyeballs out ready for TLI. 

Six one half dozen the other-- I'm sure SOMEBODY could tell us which is the best from the performance point of view, safety POV, etc...

Later ! OL JR

[MP99]

If you can crank some flight profile numbers, I can take a look at them.

Danny Deger

Whoa, that's WAY out of my department...LOL.

I can come up with crazy (kraisee? LOL) ideas, and sometimes some good remarks (at least I think so), but math & orbital mechanics??? Not happening...lol.

Paging MP99...   

Whoa yourself - sorry, I can't help with that!

I don't think this will help.  At some point you are going to go through the same velocities.  Reducing max q doesn't help a lot.

Ah yes, but for the entire, what 190 sec? of SRB burn??

Once you lose the SRBs, your problem with them goes away as well. So cut back the SSME thrust during the ascent profile with the SRBs, and when they separate, throttle up and burn the SSME engines longer to get to orbit.

That's what I'm thinking.

Conversely, I see your point - throttling-down the SSME's (through to max-Q, not SRB burnout) seems to me like it should reduce max-Q.

But Danny's later post has covered this:-

400 psf is better than 1200 psf, but even that low dynamic pressure does not solve the problem.

I think the confusion here is this started out as "an Ares I problem, because of the very high max-Q pressures".

We're still thinking of "how to reduce max-Q to get around the problem", whilst Danny now tells us that max-Q is a relatively small part of the problem, thus why Jupiter is also affected.

cheers, Martin

[MP99]

Very glad to hear that it's being worked.

"Thrust offset of LAS from velocity vector (degrees)"

Based on that statement, could I assume our hope lies in giving the LAS/capsule a different trajectory from the failing LV? Or is that already assumed in the default scenarios?

Jesse,
   Essentially what it does is pitch the Orion 'up' -- like a horse rider bringing up a horse to halt it more quickly -- instead of pitching it down in order to get it as far down range as possible.

Ross,

you're talking about turning the Orion almost 90^o to the airflow at about 750 m/s (if I'm reading the figures off the performance diagrams correctly).

Earlier, someone raised an objection to fairly small steering angles - is this a realistic manoeuvre?

cheers, Martin

[neilh]

After watching what's been happening with the Ares I, I have to say that (although I'm sure the engineers are great) I hold the management at NASA's Marshall Space Flight Center in fairly low regard. This is compounded after reading Jon Goff's note over at Selenian Boondocks remarking how in the past 30 years Marshall doesn't seem to have managed a single major project which actually succeed -- certainly not any launch projects. They have had quite a few launch projects fail miserably though, like the X-33, X-34, SLI, etc.

That said, I'm a little bit worried about what might happen to Direct if managed by MSFC. What's the likelihood that Direct, if it were chosen by the White House/NASA, would in fact be managed by MSFC? Are there any management alternatives, or is MSFC the only center with a shot of handling such a large project?

Alternatively, can the design be mostly handled by the contractor, with NASA having more of an oversight role? I think the pre-ESAS shuttle-derived architectures may have proposed this sort of arrangement.

Given a scenario where Direct would in fact be managed by MSFC under, say, Steve Cook, what do you think the chances of it not failing are?

[PaulL]

Well, FUD goes this is probably the easiest to deflect... If NASA is now objecting to the idea of a backwards docking for the Altair but suggesting that a propellant transfer from one upperstage to the other serving EDS duty is a better option (for their proposal) then the same mission achitecture can still work perfectly fine-- One J-246 launches with the LSAM/CEV (or perhaps just the LSAM and the CEV rides up on the other rocket's upperstage, the one donating it's propellant to the EDS/LSAM stack waiting on orbit.  The two rendezvous and dock (berth?) and transfer the props, undock, manuever away from each other, the Orion discards the now empty stage, rendezvous and docks to the LSAM, and the stack is ready to proceed with TLI... 

Later!  OL JR

Even better, as was pointed out to me, would be to launch the J-246+CEV+LSAM fully fueled (instead of 56% offload).  Then launch the second J-246 with NO payload fully fueled (the EDS config).  However instead of being the EDS, the second JUS is just a tanker, and transfers all of its remaining fuel to top off the CEV+LSAM+EDS.  Thus, the LSAM never has to perform any docking in LEO, it remains attached to its launch EDS.  Only the CEV detaches and then docks with the LSAM.  This would give even better performance than the current DIRECT baseline.

Mark S.

That's basically what I was getting at... one 246 launches with the LSAM and Orion and achieves orbit with the tanks still half full.  The other 246 launches with a fully tanked upperstage with only a fairing over the docking target/fuel transfer connections.  It achieves orbit half full.  The Orion can dock with it, and the prop lines connected (if a head on docking is desirable, a side berthing and fuel transfer might be preferable, dunno, really don't care, it's the idea that counts) and the props transferred from the bare stage to the TLI stack, which can then seperate and perform TLI at their leisure.  In this scenario, Orion doesn't even have to seperate from the stack and dock to Altair in LEO; the stack can go through TLI just like Apollo did.  Of course if it's not a problem for the LIDS to handle eyeballs out TLI, disposing of the slot panels might increase mass thru TLI. 

THe other way could work nearly the same, Orion on one 246 which then sidles up to the Altair on the EDS in orbit, with half of the props remaining in both stages.  The Orion transfers the props in it's upperstage to the EDS/Altair stack, moves off, expends the empty stage, and docks with the Altair eyeballs out ready for TLI. 

Six one half dozen the other-- I'm sure SOMEBODY could tell us which is the best from the performance point of view, safety POV, etc...

Later ! OL JR

Ross would have to confirm that, but I don't think that the Jupiter US is strong enough to take a payload and a full propellant load.  When a payload is carried (such as the J-24x CLV flight), the equivalent mass in propellant is removed in order to limit the total mass at no more than 200 mt. By the way, using this relatively "weak" US (optimized to carry propellant only) helps to achieve a very high pmf.

PaulL

[MikeAtkinson]

There are three Jupiter 130 test flights planned, are there any ideas on how to use them? Obviously you could just launch non-functional dummy payloads, but that seems wasteful. Would something like a prototype propellant depot make a good payload?

[marsavian]

And it has less to do with the various launch options, including but not limited to DIRECT, than it has to do with the schedule for Orion. In all cases Orion is the long pole and they don't believe L/M's IOC schedule for her. That pushed everyone's schedule to the right in the study. (the line-thru is mine)

My sources say that it applies to LVs as well as Orion.  I should have shut up and let the analysis report speak for itself in about 6-8 weeks. 

I've had a dreadful day trying to get onto NSF without luck.   Seems my local ISP's DNS is all shot to hell and back

I finally managed to get on this evening though and, boy, it has been busy around here, hasn't it?

I'm not sure what I'm allowed/should say regarding some of the things, but I'm going to speak out on this topic just to prevent any misconceptions happening in a vacuum of data.

The dates which we submitted to Aerospace Corporation were:

Jupiter-130 IOC -- March 2014
Jupiter-241 IOC -- 2018

We've seen some of the results already and without providing specific details, BOTH of those dates have been improved upon to the tune of at least 1 whole year and 2 years respectively -- which we aren't surprised about given that we packed all our schedules with plenty of surplus margins.

Given the analysis date of 2013, and lets assume it was "late" 2013, it would indeed be roughly 1.5 years ahead of Ares-I's "official" deployment date of March 2015.   So that does seem to fit all of the comments made earlier today, no?

My question is this:   If it were to be combined with a moderate 2 year "stretch" (as opposed to an extension) to Shuttle's current 7-flight manifest, would that not see at least one of the three planned Jupiter test flights off the ground before the last Shuttle flew?

Gap?   What Gap!

Ross.

That's just awesome, you and the MSFC rebels come in under schedule while official MSFC comes in way over . I thought J-130 was a 4 year job and Aerospace obviously agree. It's good that you padded all your numbers with excess margins, you look the much better for it. Not only would there be relatively little gap but damn 2020 for the Moon is still doable. Great professional job by your team.

[marsavian]

If the basic principles of DIRECT were adhered to I can't see how it could be screwed up. As long as no new engines were suddenly thrown in the mix like the way J2/RS-68 were substituted for SSME from the ESAS Ares I/V it should be ok. Pick a HLV end point whether it's J-241/6 or Ares V classic and stick to it, don't tinker, and build the earlier upperstage less variant asap so the manned spaceflight gap is minimized.

[Ben the Space Brit]

That's a pretty good question.  NASA politics being what it is, I'd assume that MSFC would end up with overall project management responsibility.  KSC and MAF would probably end up sharing 'hardware' for the Jupiter CCB because of their familiarity with the components in question.  The JUS/EDS would end up with whatever centres are currently doing hardware for the AIUS and AVEDS.

However, yes, MSFC would end up running the show.  I think that is why Aerospace Corp added a 12-month civil service inefficiency coefficient to the schedule for DIRECT and NSC.