Studying the issues with LV13.1 (Ares I classic)

[Downix]

Earlier on the SD-HLV two stage thread, got a bit riled up at the claims made about the J-2X, that it was designed with the purpose of being both an ideal US engine and EDS engine, so went and dove into the ESAS to uncover the goal, and the end result.  What I discovered was that within the ESAS, it dismissed the replacement of SSME with the J-2S+ (the engine which eventually became the J-2X), stating that such a move would torpedo both cost and timeline, which is exactly what happened.  I also saw the target specifications for the J-2S+, and the J-2X fails to meet the target for EDS, sacrificing them to fulfill the new role on Ares I.

So, this got me to think, what alternative did they have in 2005?  This got me to wracking my brain, they did not want to put a new engine, as the J-2X was, on the long pole.  Then it hit me, there was an air-startable engine already in service at that time, not that pricey an engine, with a long track record including being used for manned flight.

The LR-87.

The desire for an LH2 engine could be addressed, as the LR-87 has been flown with both hypergolics and RP-1, and done full testing with LH2.  The performance for two of the LH2 version would have higher thrust than the SSME, with lower isp, and the Hypergol would be even better for thrust, again at a loss of isp.  Two LR-87-11's would fit under the Ares I Classic tank, and together they could produce 2,185.6 kN of thrust vac, 1,721.7 kN SL.  It also gives a buffer, should the engine effort fall behind schedule, you can load the AIUS with Hypergolics instead of LH2 and run the engines as/is.  Using the existing 4-seg SRB, the LH2 version lifts 25mT and the Hypergol version can lift 23.4 mT.

So, what you'd have is a viable launch vehicle, even if not ideal due to the use of an SRB as first stage, but a workable one without a long-pole.  Fly the hypergol version first, waiting for the LH2 version to come online.  The VAB is dealing with hypergols already from the OMS, so this is a non-issue.  The total GLOW is even light enough to allow it to be carried to the pad w/o fueling once on the pad.  While, yes, Hypergol's are not the ideal launch fuel, a bird in the hand is worth two in the bush.  What killed Constellation was putting too many long-poles up front.

Ah, the fun of heated discussions making me ponder the situation, what went wrong, and what could have been done instead.

[Jim]

The OMS is basically empty in the VAB and loaded at the pad.  The proposed amount hypers would not be allowed in the VAB, much less be loaded there.

Production capability of the LR-87 was shutdown long ago, and it would be almost a new start like the J-2

[beb]

Production capability of the LR-87 was shutdown long ago, and it would be almost a new start like the J-2

Trust Jim to throw cold water on a hot idea.

So it would appear that Constellation was doomed from the start by being given an impossible short deadline when the U.S.  simply lacked the kinds of engines needed for the mission.

[Downix]

Production capability of the LR-87 was shutdown long ago, and it would be almost a new start like the J-2

Trust Jim to throw cold water on a hot idea.

So it would appear that Constellation was doomed from the start by being given an impossible short deadline when the U.S.  simply lacked the kinds of engines needed for the mission.

There was one last engine, as I mentioned a few times: AJ-26.

*edit* also checked, there are several LR-87-AJ11's in storage which could be used for initial flight testing.  I even located one of the LH2 modified units.  And I also checked, as of 2001 the LR-87 was in production, and there is nothing to discuss discontinuing of production until 2004, less than a year before we are discussing.  Restarting production of an existing engine within such a short period is not a game breaker, and there would be existing engines to utilize in the interim until production was ready.

But yes, Constellation was doomed due to the inability of management to read their own report.  Reading the ESAS report, there was a chain of options for crew launch, based on time to delivery, development schedule, and cost as well as crew safety and reliability.  The chain went from LV13, the 4-seg w/ 1 SSME Ares I to an Atlas V HLV as/is, to Delta IV Heavy as/is, to Delta IV Heavy w/ a new J-2S+ based upper stage, to the Atlas V HLV w/ the new J-2S+ based upper stage, to *then* to the LV17 5-segment w/ J-2S+ upper stage.  They even gave a breakdown as to why LV17 and LV19 (the two 5-segment based designs in the study) were so far down the chain, listing concerns over 5-segment vibration along with the time and cost to develop not just one, but two new engines before even basic flight testing could be started.  They also voiced concerns that the development may not give the performance necessary, and that such performance loss would result in even further delays as the CEV would need to be re-designed.  They even discussed an evolution type path, to prevent such a critical loss of access, that if LV13 would not work, to use the Atlas V HLV as/is, developing the future LV17 upper stage so that it could be fitted up to the Atlas V as an initial upgrade, and then if the 5-segment SRB can meet performance, replacing the three CCB's with the 5-segment only at that time.  This would have eliminated the long-poles immediately from the path, while still giving the potential for the future for growth.

[Downix]

This morning I had a bit of epiphany.  One of the concerns I've had with the Ares I design, a concern which was reinforced by the Ares IX flight, is that the residual fuel within the SRB casing could add a pulse of thrust after staging, and push the second stage into the upper before the engines had fully engaged.

This morning I looked at the old N-1 and Soyuz, and it struck me a solution so brilliant yet simple. 

[Downix]

Not saying to be exact, but the idea was to enable the upper stage engine(s) to fire while still attached to the first stage, enabling the venting of exhaust.  Could be through blow-away panels or some such to use as a channel.

[Jim]

They didn't reuse the lower stages.  Ares I was to use ullage and retrorockets to prevent recontact.

[simonbp]

Not saying to be exact, but the idea was to enable the upper stage engine(s) to fire while still attached to the first stage, enabling the venting of exhaust.  Could be through blow-away panels or some such to use as a channel.

Um, they tried that for CLV/Ares I. IIRC, problem was the solid first stage accelerated so fast that the lateral aero loads at max Q crushed the open truss interstage. Thus, they went with a much more beefy solid interstage.

[Downix]

They didn't reuse the lower stages.  Ares I was to use ullage and retrorockets to prevent recontact.

You'd need a retrorocket with as much power as the SRB in the last 10% of it's burn, nothing I've seen in any proposal addresses that with the 5-segment.

Let us compare.  To stop a 4-segment SRB at the recommended staging point, with 10 seconds of potential burn remaining for safety (typically it is 6 seconds, but I like margin).  At this point, we would need between 218kN and 667kN.  Not horrible, could use a few of the high-thrust STAR's with the burn time reduced, not a game-stopper.

Now, let's do the same on the 5-segment, using ATK's own test data.  The first test, you would have needed 1,733 kN.  The second, you would have needed 1,848 kN.  Now you're in trouble.

[Jim]

Let us compare.  To stop a 4-segment SRB at the recommended staging point, with 10 seconds of potential burn remaining for safety (typically it is 6 seconds, but I like margin).

It was staged at burnout

[Downix]

Let us compare.  To stop a 4-segment SRB at the recommended staging point, with 10 seconds of potential burn remaining for safety (typically it is 6 seconds, but I like margin).

It was staged at burnout

You can't do that, because burnout is inconsistant.  Studying the now 262 SRB burnout times (not counting Challenger for they did not burn to burnout), burnout occurs between 126 seconds and 132 seconds without any pattern.

[ugordan]

What do you mean you can't do that? If staging is triggered when the chamber pressure drops below a certain threshold, what difference does it make if it happens a few seconds earlier or later?

[Downix]

What do you mean you can't do that? If staging is triggered when the chamber pressure drops below a certain threshold, what difference does it make if it happens a few seconds earlier or later?

Because out of those 262 SRB burnouts, the pressure has dropped then raised again 114 times within the last 10 seconds of burn, with three of those being reported as 0 pressure before reappearing for one last burst.  You must stage before SRB burnout or else you endanger the crew.

[kch]

What do you mean you can't do that? If staging is triggered when the chamber pressure drops below a certain threshold, what difference does it make if it happens a few seconds earlier or later?

Because out of those 262 SRB burnouts, the pressure has dropped then raised again 114 times within the last 10 seconds of burn, with three of those being reported as 0 pressure before reappearing for one last burst.  You must stage before SRB burnout or else you endanger the crew.

Were there any instances of that last burst persisting past the 132 second point?  If not, would it be reasonably safe (I know, nothing's 100%) to delay staging (coast) to around 135-140 seconds?  Roughly how much performance penalty would be incurred by doing so?  Just wondering if that's a workable procedure.

[Downix]

What do you mean you can't do that? If staging is triggered when the chamber pressure drops below a certain threshold, what difference does it make if it happens a few seconds earlier or later?

Because out of those 262 SRB burnouts, the pressure has dropped then raised again 114 times within the last 10 seconds of burn, with three of those being reported as 0 pressure before reappearing for one last burst.  You must stage before SRB burnout or else you endanger the crew.

Were there any instances of that last burst persisting past the 132 second point?  If not, would it be reasonably safe (I know, nothing's 100%) to delay staging (coast) to around 135-140 seconds?  Roughly how much performance penalty would be incurred by doing so?  Just wondering if that's a workable procedure.

The longest burn I saw ended at 132.1 seconds.  If you staged at 135 seconds, you'd loose some momentum.  But, there is a way to help offset this.

Pondering it a bit, using the ullage discussion a bit.  If they used a few small solids attached to the outside of the upper stage, with ~5 second burn times, they may be able to off-set this.  Looking at ATK's catalog, 8 Star 8's would do the job.

[ugordan]

Because out of those 262 SRB burnouts, the pressure has dropped then raised again 114 times within the last 10 seconds of burn, with three of those being reported as 0 pressure before reappearing for one last burst.  You must stage before SRB burnout or else you endanger the crew.

That's what the BDMs and ullage motors on 2nd stage were for. I am well aware SRBs don't shutdown completely and rapidly, but it's not an insurmountable challenge.

And no, I don't like Ares I either.

[Downix]

Because out of those 262 SRB burnouts, the pressure has dropped then raised again 114 times within the last 10 seconds of burn, with three of those being reported as 0 pressure before reappearing for one last burst.  You must stage before SRB burnout or else you endanger the crew.

That's what the BDMs and ullage motors on 2nd stage were for. I am well aware SRBs don't shutdown completely and rapidly, but it's not an insurmountable challenge.

And no, I don't like Ares I either.

Never said it was an insurmountable challenge.  And I'm with you.

Truth be, I don't hate Ares I, nor even really dislike it.  The *idea* has a certain appeal.  But the reality, just doesn't work.

Maybe a large segmented Hybrid motor? 

[kch]

Maybe a large segmented Hybrid motor? 

Now there's a thought! 

[Downix]

Ok, out of morbid curiosity I took one of the ESAS ideas that was implied and explored it, namely using a different US on the EELV's.  I used the LV17's US, using the J-2S+ but with the AIUS weight gain to reflect the evolutionary path. First I took a Delta CBC sans engine, put an SSME on the base, put an AIUS on top, and then added four ATK GEM-60.  It could lift over 25mT to the ISS.  When I tried with two, it did not lift off the pad, not enough ground thrust.  When I tried with an RS-68, with the four GEM-60's I got it to 23mT.  Two, 20mT.  None, it could not lift off of the pad, it was too heavy.  Then another thought, a Heavy with an SSME on the core, which hit 44mT.  Remove the US entirely, 26mT. Swap out Delta CBC's with Atlas CCB's, 29mT.

Then I tried with a stock Atlas CCB for the first stage.  As/is, it could loft 18mT.   Adding a single Atlas SRB got it to 22mT, then adding two got it to 25mT.

This tells me that the ESAS missed a whole evolutionary chain in the process.  The ESAS had mentioned launching on the EELV heavies, but with their demand for single-engine for safety they put the 4-seg+SSME ahead of them.  Here is a way to have closed the gap, and not had any long poles while giving them the "out" they wanted.

Baseline a NASA-derived EELV's for initial launch capability, with a staged evolutionary path to hit the 5-seg first stage and J-2S+ for US work. The initial launch vehicle would be the combo Delta CBC w/ SSME paired with Atlas CCB's, with no US.  This configuration would, per the rules set forth for safety in the ESAS report, bring the safety of the system from Delta IV Heavy's LOM of 1:172/LOC of 1:1,100 to LOM of 1:384/LOC of 1:1,864.  The cost, per ESAS calculation methodology, would also be 0.95, less than both LV13 and LV17.

This would give initial capability, a NASA vehicle which uses parts supplied by Lockheed and Boeing.  They would then work on the LV17 US and 5-segment booster (as the 5-segment is needed for the Ares V anyways) without the need to modify the J-2S+ for higher thrust, keeping it's higher ISP form.  If the US works out, great, can switch to a single Atlas CCB for crew launch, and same with the 5-segment SRB as first stage.  At no point do you have a critical path element tied to an undeveloped and untested element.  Flying Delta+Atlas together is unproven, so worst case switch to pure Delta w/ SSME on center configuration instead or stock Atlas V HLV.  This would also give more R&D money to key areas over the final proposal, from the RD-180/alternative engine domestic production startup.  Alternatively, and a way to keep ATK happy and still meet the demands, ATK as part of the 5-segment program made a more scalable segment design, and two two-segment SRB's, one on each side of the core, would give it more than enough push off the ground.  Or could fund development of more powerful GEM's, which would benefit both this project as well as ULA.  In addition, the J-2S+, as planned (and looked likely to hit based on later data) would have been a solid engine for the EELV's, and a cut-down form of the AIUS (could shrink it by 1/3 w/o issue based on the design) which levereged Centaur/DCSS technology (which it does if you study it) would have been a great US for both EELV's, rivaling ACES.

[Downix]

Had another thought, and instead of swapping the US engine, I re-configured the 4 SRB segments into two 2-segment SRBs (taking the middle two segments out of the 4-segment SRB, which has been proposed by Thiokol and later ATK on a few occasions, and based on data should work fine) and strapped them to the side of the ESAS LV13 upper stage.

Worked fine, lifting 26mT to the iSS>

[TrueBlueWitt]

Had another thought, and instead of swapping the US engine, I re-configured the 4 SRB segments into two 2-segment SRBs (taking the middle two segments out of the 4-segment SRB, which has been proposed by Thiokol and later ATK on a few occasions, and based on data should work fine) and strapped them to the side of the ESAS LV13 upper stage.

Worked fine, lifting 26mT to the iSS>

Stumpy Jr?

[Downix]

Had another thought, and instead of swapping the US engine, I re-configured the 4 SRB segments into two 2-segment SRBs (taking the middle two segments out of the 4-segment SRB, which has been proposed by Thiokol and later ATK on a few occasions, and based on data should work fine) and strapped them to the side of the ESAS LV13 upper stage.

Worked fine, lifting 26mT to the iSS>

Stumpy Jr?

Would be pretty ugly, but it would fly.

[madscientist197]

With what ISP? Did you assume a new optimised throat?

[Downix]

With what ISP? Did you assume a new optimised throat?

I used the isp off of the Athena 3 proposal of 246.  Reading that proposal, it did not look like they were optimizing the throat over the Shuttles.

[Downix]

Got to pondering a bit more, the twin 2-seg with a new core stage still seems off, it means more development for the program.  Within the RAC-2 studies was one proposal which had Block I as the upper stage w/o the first stage, so, I did a bit of a switcharoo, and instead of developing an AIUS, I had the EDS developed, using the same 8.4m tooling at Michoud as the original plan, added the SRB support beam to the interstage, and viola, we have a core for our twin 2-seg SRB.  To speed up development, I did not use the EDS's new insulation, instead utilizing the existing ET orange thermal protection, so the new insulation would need to be added into development later on.  In addition, the tank is upside down, with the LOX to the front while for EDS it would be to the rear.

This would have been ready to fly in 2008, requiring minimal development.  This could loft up to 30.4 tonnes to the ISS. 

Once the J-2S+ engine was ready, the Block II program begins,  substituting the J-2S+ for the SSME.  This increases the payload to 36 tonnes to the ISS.  When Ares V is ready, swap interstage with one not sporting the SRB support to lighten the load and use the new, non-popcorning insulation, but keep the existing design for crewed launch. 

Consolidation of manufacturing, tooling, and employees makes it more efficient an operation.  This would have reduced the cost to develop the Ares V as well, with the EDS already being 80% completed, and enabled systems testing in the process.  When the 5-segment design for SRB was completed, the 2-segment now becomes the 5-segment with the 3 middle pieces eliminated. It would have fulfilled the ESAS CLV requirements, taken less time and money, and have been ready for flight by the required date.  No long poles, no costly up-front development, none of that.

[Silmfeanor]

It looks....weird. Gnomish?
I like it though, although I think that at this point building better fitting SRB's instead of shortening them to this degree might make a BIG diffirence in efficiency and perhaps safety.

[Downix]

It looks....weird. Gnomish?
I like it though, although I think that at this point building better fitting SRB's instead of shortening them to this degree might make a BIG diffirence in efficiency and perhaps safety.

It is just a quick object study based on the ESAS.  The evolution of Ares I became the real issue, resulting in the delays and cost overruns.  I enjoy "what if" scenarios, so this is a result of that.  Is it a solid next-gen launcher for now?  No, the realities in place today make this unnecessary.  Although it is fun to ponder what if.

[FinalFrontier]

Got to pondering a bit more, the twin 2-seg with a new core stage still seems off, it means more development for the program.  Within the RAC-2 studies was one proposal which had Block I as the upper stage w/o the first stage, so, I did a bit of a switcharoo, and instead of developing an AIUS, I had the EDS developed, using the same 8.4m tooling at Michoud as the original plan, added the SRB support beam to the interstage, and viola, we have a core for our twin 2-seg SRB.  To speed up development, I did not use the EDS's new insulation, instead utilizing the existing ET orange thermal protection, so the new insulation would need to be added into development later on.  In addition, the tank is upside down, with the LOX to the front while for EDS it would be to the rear.

This would have been ready to fly in 2008, requiring minimal development.  This could loft up to 30.4 tonnes to the ISS. 

Once the J-2S+ engine was ready, the Block II program begins,  substituting the J-2S+ for the SSME.  This increases the payload to 36 tonnes to the ISS.  When Ares V is ready, swap interstage with one not sporting the SRB support to lighten the load and use the new, non-popcorning insulation, but keep the existing design for crewed launch. 

Consolidation of manufacturing, tooling, and employees makes it more efficient an operation.  This would have reduced the cost to develop the Ares V as well, with the EDS already being 80% completed, and enabled systems testing in the process.  When the 5-segment design for SRB was completed, the 2-segment now becomes the 5-segment with the 3 middle pieces eliminated. It would have fulfilled the ESAS CLV requirements, taken less time and money, and have been ready for flight by the required date.  No long poles, no costly up-front development, none of that.

I smell lawn gnomes. And they appear to have a space program.

[MP99]

Within the RAC-2 studies was one proposal which had Block I as the upper stage w/o the first stage, so, I did a bit of a switcharoo, and instead of developing an AIUS, I had the EDS developed, using the same 8.4m tooling at Michoud as the original plan, added the SRB support beam to the interstage, and viola, we have a core for our twin 2-seg SRB.

To confirm, this is with an air-start SSME?

Very interesting config.

cheers, Martin

[Downix]

Within the RAC-2 studies was one proposal which had Block I as the upper stage w/o the first stage, so, I did a bit of a switcharoo, and instead of developing an AIUS, I had the EDS developed, using the same 8.4m tooling at Michoud as the original plan, added the SRB support beam to the interstage, and viola, we have a core for our twin 2-seg SRB.

To confirm, this is with an air-start SSME?

Very interesting config.

cheers, Martin

Nope, ground start.  When it switched to J-2X it would have then been air-start.  That is why the performance jumped despite loosing both thrust and isp.

[ugordan]

Nope, ground start.  When it switched to J-2X it would have then been air-start.  That is why the performance jumped despite loosing both thrust and isp.

The location of the nozzle strikes me as problematic for airstart. Seems to me it would get cooked before ignition.

[madscientist197]

That's a good point as there isn't any active cooling until the engine in actually going.

[Downix]

Adjusting for ground start, the performance is similar enough for rounding error. The J-2X would run at its lower 40% thrust rating until SRB separation, then throttle up for 34.5 tonnes.

[Jason1701]

What about if you added an extra SRB segment below the two existing ones? Then the nozzle wouldn't be in the line of fire.

Or replace the SRBs with Atlas CCBs

[MP99]

If you swap the O2 tank under the thrust beam it would lift the J2 without going to 3-segs.

Cheers. Martin

[Downix]

If you swap the O2 tank under the thrust beam it would lift the J2 without going to 3-segs.

Cheers. Martin

Too heavy in back upon SRB staging then.

As these SRB segments are much smaller, if we retained the original SRB parachutes rather than cut them down, we could add a dummy segment or half-segment to the top.

[Downix]

Ok, proof I am completely bonkers.  In a discussion about dead-ends, the discussion turned to the X-33, and I mentioned how I liked the Rockwell X-33 design due to how pragmatic it was in comparison to the selected Lockheed design.  I them lamented how even then, it still could never be SSTO.  Someone else in the group then popped up "If the point is to be re-usable, why not just re-use the Shuttle SRB? It's already re-usable."  Which then got gears turning.  The ESAS requirement for Ares I was a single SSME and a single 4-segment SRB, so I took the Rockwell X-33, with it's single SSME, cleaned it up for crewed flights, and strapped an SSME to the bottom. 

I then crunched the numbers through Schillings, and it would work as an orbital crew vehicle.  It also avoids the pitfall which started the chain of failure with Ares I, that the SSME was too expensive to throw away, and too expensive to make air-startable.  I took the X-33 and Platypus both (all 5 revisions of Platypus at that) and merged their lines with the existing shuttle systems.  I even included an F-111 ejection module that seats 7.

Stupid OCD, 5 hours of my life gone.

[Rocket Science]

Ok, proof I am completely bonkers.  In a discussion about dead-ends, the discussion turned to the X-33, and I mentioned how I liked the Rockwell X-33 design due to how pragmatic it was in comparison to the selected Lockheed design.  I them lamented how even then, it still could never be SSTO.  Someone else in the group then popped up "If the point is to be re-usable, why not just re-use the Shuttle SRB? It's already re-usable."  Which then got gears turning.  The ESAS requirement for Ares I was a single SSME and a single 4-segment SRB, so I took the Rockwell X-33, with it's single SSME, cleaned it up for crewed flights, and strapped an SSME to the bottom. 

I then crunched the numbers through Schillings, and it would work as an orbital crew vehicle.  It also avoids the pitfall which started the chain of failure with Ares I, that the SSME was too expensive to throw away, and too expensive to make air-startable.  I took the X-33 and Platypus both (all 5 revisions of Platypus at that) and merged their lines with the existing shuttle systems.  I even included an F-111 ejection module that seats 7.

Stupid OCD, 5 hours of my life gone.

Looks like a scaled up X-37...

[Downix]

Looks like a scaled up X-37...

A bit older, however.  Here's Rev 3 of the Platypus IIRC

[Rocket Science]

Looks like a scaled up X-37...

A bit older, however.  Here's Rev 3 of the Platypus IIRC

An oldie, but a goodie....for your desktop...
http://www.silentthundermodels.com/nasa_space_models/orbital_space_plane.html

[Downix]

Ah well, just me getting obsessive.  Hope everyone had a good laugh.

[Downix]

Incidentally, if you noticed that thing did not have a payload bay.  It could be used for payload delivery, however, if you removed the crew module and installed a payload system instead.  Automated landing system for those operations.  Not large enough for DoD missions however.

Something else to notice, rather than having special doors for the SRB mount, I used the landing gear doors.  The actual gear is covered during launch to be protected, by the SRB mount support structure which is jettisoned with the booster.  I figured less doors to worry about in the belly that way.  I also worked hard to re-use the existing shuttle RCS and OMS systems.  The OMS and SSME are in a swappable pod, so it can be prepared away from the vehicle itself, speeding up vehicle return to flight between missions.

[RanulfC]

Looks like a scaled up X-37...

A bit older, however.  Here's Rev 3 of the Platypus IIRC

Plug-Nozzle on that thing? Where did you find the "other" versions? I've only seen the one...

Randy

[Downix]

Looks like a scaled up X-37...

A bit older, however.  Here's Rev 3 of the Platypus IIRC

Plug-Nozzle on that thing? Where did you find the "other" versions? I've only seen the one...

Randy

Up ship has them.

[Prober]

Got to pondering a bit more, the twin 2-seg with a new core stage still seems off, it means more development for the program.  Within the RAC-2 studies was one proposal which had Block I as the upper stage w/o the first stage, so, I did a bit of a switcharoo, and instead of developing an AIUS, I had the EDS developed, using the same 8.4m tooling at Michoud as the original plan, added the SRB support beam to the interstage, and viola, we have a core for our twin 2-seg SRB.  To speed up development, I did not use the EDS's new insulation, instead utilizing the existing ET orange thermal protection, so the new insulation would need to be added into development later on.  In addition, the tank is upside down, with the LOX to the front while for EDS it would be to the rear.

This would have been ready to fly in 2008, requiring minimal development.  This could loft up to 30.4 tonnes to the ISS. 

Once the J-2S+ engine was ready, the Block II program begins,  substituting the J-2S+ for the SSME.  This increases the payload to 36 tonnes to the ISS.  When Ares V is ready, swap interstage with one not sporting the SRB support to lighten the load and use the new, non-popcorning insulation, but keep the existing design for crewed launch. 

Consolidation of manufacturing, tooling, and employees makes it more efficient an operation.  This would have reduced the cost to develop the Ares V as well, with the EDS already being 80% completed, and enabled systems testing in the process.  When the 5-segment design for SRB was completed, the 2-segment now becomes the 5-segment with the 3 middle pieces eliminated. It would have fulfilled the ESAS CLV requirements, taken less time and money, and have been ready for flight by the required date.  No long poles, no costly up-front development, none of that.

Just found this post, and believe this would have worked.  I had the same basic idea, as the major problem with Ares I was the single stack.  Get rid of the single stack and all kinds of vibration etc. would have been gone.

I found the one design in the NASA files (Boeing SRB-X), with a dual set of solids and the 2nd stage in the middle, it looked workable.

Taking us back to the first designs of the Ares I.
My idea would have been 3-4 solid segments on each side using as much of the Shuttle  launch pad config as possible.   Unlike your design, my idea would have been to move the center 2nd stage up higher.   The Solids would do most of the work, drop off and 2nd stage takes over, per the Ares I design.

A derivative of this idea for a quick supply launcher for the ISS would include these changes.   Since the 2nd stage is moved away from the direct fire area, the RS-68 engine might be used.
A) As long as the fame front was away from the Solids.
B) The RS-68 nozzle didn’t need to contend with the flames and heat from the solids it would have worked.

[Jim]

I found the one design in the NASA files (Boeing SRB-X), with a dual set of solids and the 2nd stage in the middle, it looked workable.

It was the worse SDLV design ever and a bigger kludged than Ares I.  It is not viable

[Downix]

I found the one design in the NASA files (Boeing SRB-X), with a dual set of solids and the 2nd stage in the middle, it looked workable.

It was the worse SDLV design ever and a bigger kludged than Ares I.  It is not viable

When I first saw Ares I the SRB-X was the first thing to go through my mind.

I'll admit, the *idea* of Ares I is ok, but it rapidly went overboard.

[Prober]

I found the one design in the NASA files (Boeing SRB-X), with a dual set of solids and the 2nd stage in the middle, it looked workable.

It was the worse SDLV design ever and a bigger kludged than Ares I.  It is not viable

When I first saw Ares I the SRB-X was the first thing to go through my mind.

I'll admit, the *idea* of Ares I is ok, but it rapidly went overboard.

I kinda put myself into how to fix the very first design.

[Patchouli]

I found the one design in the NASA files (Boeing SRB-X), with a dual set of solids and the 2nd stage in the middle, it looked workable.

It was the worse SDLV design ever and a bigger kludged than Ares I.  It is not viable

When I first saw Ares I the SRB-X was the first thing to go through my mind.

I'll admit, the *idea* of Ares I is ok, but it rapidly went overboard.

The design may have had merit if it did not need to have a 23MT payload or carry a crew.have commonality with the EDS, and was proposed ten or fifteen years earlier.

The biggest problem with it the EELVs already did the exact same job but for lower cost.

Another problem growing payload requirements made Ares V loose commonality with Ares I which eliminated it's second purpose to help pay for the HLV.
What the whole ESAS architecture needed was to give up on the 1.5 launch architecture and go to two launches.

But a vehicle like Ares I could have been successful if it was proposed back in the 80s or 90s and the target payload set to something well within the reach of the existing 4 segment RSRM.

[Downix]

I found the one design in the NASA files (Boeing SRB-X), with a dual set of solids and the 2nd stage in the middle, it looked workable.

It was the worse SDLV design ever and a bigger kludged than Ares I.  It is not viable

When I first saw Ares I the SRB-X was the first thing to go through my mind.

I'll admit, the *idea* of Ares I is ok, but it rapidly went overboard.

The design may have had merit if it did not need to have a 23MT payload or carry a crew.have commonality with the EDS, and was proposed ten or fifteen years earlier.

The biggest problem with it the EELVs already did the exact same job but for lower cost.

Another problem growing payload requirements made Ares V loose commonality with Ares I which eliminated it's second purpose to help pay for the HLV.
What the whole ESAS architecture needed was to give up on the 1.5 launch architecture and go to two launches.

But a vehicle like Ares I could have been successful if it was proposed back in the 80s or 90s and the target payload set to something well within the reach of the existing 4 segment RSRM.

I actually like the 1.5 architecture as a concept.  The decided upon implimentation of that is where I had issue, for the very reasons you list here.

A 1.5 EELV-derived architecture would have met the requirements and been ready far sooner and with less cost than what we were given.

[Patchouli]

I still say the 1.5 architecture was fundamentally flawed.

It put too many requirements on the CaLV causing it to grow into a 188MT monster.

Even a 2.5 launch architecture would be easier though a smaller SDLV would be easier to man rate and eliminated the third launch.

In my opinion the Apollo mindset was the biggest thing wrong with project Constellation.
It was Apollo except the crew rode up on a separate smaller rocket and LOI was moved to the lander.

They pretty much threw out all the lessons learn on ISS and the Shuttle.
CxP even excluded low risk technologies that could have made it sustainable, such as SEP ferries for cargo ,fuel depots, and L1 staging.

[Downix]

I still say the 1.5 architecture was fundamentally flawed.

It put too many requirements on the CaLV causing it to grow into a 188MT monster.

Even a 2.5 launch architecture would be easier though a smaller SDLV would be easier to man rate and eliminated the third launch.

In my opinion the Apollo mindset was the biggest thing wrong with project Constellation.
It was Apollo except the crew rode up on a separate smaller rocket and LOI was moved to the lander.

They pretty much threw out all the lessons learn on ISS and the Shuttle.
CxP even excluded low risk technologies that could have made it sustainable, such as SEP ferries for cargo ,fuel depots, and L1 staging.

I will have to humbly disagree with you.  The flaws of the Ares I caused the growth of Ares V, not the 1.5 architecture itself.  Remember, Ares V needed to push 90 tonnes to TLI.  Under the original ESAS study, it would have managed that while only putting 130 tonnes into LEO.  The changes to Ares I, however, necessitated the changes to both the 5-segment and J-2X engine which harmed Ares V's TLI performance, which forced it's growth to maintain the same TLI profile.

Using the same 1.5 architecture using the EELV-derived solution within ESAS, LV2 paired with LV7.4, you found yourself with a setup which was capable of delivering the same payload as Ares V would have despite pulling a lower LEO capability. 

So please, do not blame the architecture for the shortcomings of a particular implimentation of that architecture.  AJAX is a 1.5 architecture as well don't forget.

[madscientist197]

It's been a very long time since I've read the original threads on these issues, but wasn't part of the problem that Nasa seriously underestimated the mass of the LSAM in ESAS?

[renclod]

I still say the 1.5 architecture was fundamentally flawed.

That is an opinion... a fundamentally flawed opinion, I say.

It put too many requirements on the CaLV causing it to grow into a 188MT monster.

They wanted the 180+metric tons to LEO for MARGIN.
[edit: meaning, if we start with 180+ requirements, we will end with 150+ flight]

Even a 2.5 launch architecture would be easier though a smaller SDLV would be easier to man rate and eliminated the third launch.

Which shows you are lost in the architectural maze.
2.5 is sustainable for lunar ?! maybe for Mars, buddy...

In my opinion the Apollo mindset was the biggest thing wrong with project Constellation.
It was Apollo except the crew rode up on a separate smaller rocket and LOI was moved to the lander.

CxP is Apollo for cargo.
Once you understand - fat chance of that, eh ?! -that a lunar base needs more cargo traffic than crew traffic (in the first few decades at least) then you get to see the reason behind single launch cargo to the Moon.
If you ever get to wrap your brain around that, you'll see that LOI insertion must move from crew spacecraft to cargo spacecraft. Easy.
And then comes the great revelation: crew launch must be on a separate smaller rocket, and the whole beauty of 1.5 hits you, complete with the need for commonallity between the cargo launcher and the crew launcher.

They pretty much threw out all the lessons learn on ISS and the Shuttle.

Quite the contrary, they took in those lessons.

CxP even excluded low risk technologies that could have made it sustainable, such as SEP ferries for cargo ,fuel depots, and L1 staging.

Oh yeah, SEP ferries, fuel depots and L1 staging are low risk technologies - if you can talk the Area 51 aliens into paying for it and managing it and bailing it out when in dire need.

 

[Downix]

It's been a very long time since I've read the original threads on these issues, but wasn't part of the problem that Nasa seriously underestimated the mass of the LSAM in ESAS?

No.  The ESAS specified a 45 tonnes LSAM with 2 tonnes of margin added, and the final LSAM was 45,864 kg, well within the margin.  It also specified a 23 tonnes CEV, which Orion at it's heaviest when combined with the final Altair still was within margin.

The original TLI injection was to be 68.6 tonnes, don't forget.  It could push 72 tonnes, hence the margin with both Orion and Altair, which neither one went over.

[Patchouli]

Oh yeah, SEP ferries, fuel depots and L1 staging are low risk technologies - if you can talk the Area 51 alliens into paying for it and managing it and bailing it out when in dire need.

 

The Constellation architecture was fundamentally flawed so much so it cause in insurrection among the engineers.

Team direct already showed why the 1.5 architecture was bad and why two smaller HLVs can be better then one monster LV.

It's biggest flaw it was very unimaginative and expensive and inherited all the short comings of the Apollo architecture.

I literally face palmed when I saw Constellation for the first time and knew it was going to fail.

Space exploration is supposed to develop new technologies if you are afraid to trying anything new as in CxP then you are in the wrong business.

As for SEP ferries being low risk they are relatively low risk.
DS1 and Smart 1 already proved solar electric to be viable.

Telerobotic operations were proven on on ISS resupply with the ATV and missions like Orbital Express.

Boeing had them as a key part of their architecture.

I consider cryogenic fuel deports even higher risk then SEP tugs but not so high they should be avoided.

But ULA says the near zero boil off technology needed for fuel depots is doable.
They launch rockets for a living and know more on the subject then the designers of the ESAS architecture.

[Downix]

Oh yeah, SEP ferries, fuel depots and L1 staging are low risk technologies - if you can talk the Area 51 alliens into paying for it and managing it and bailing it out when in dire need.

 

The Constellation architecture was fundamentally flawed so much so it cause in insurrection among the engineers.

Team direct already showed why the 1.5 architecture was bad and why two smaller HLVs can be better then one monster LV.

But DIRECT themselves had a 1.5 architecture, the J-130 + J-246.  The point of DIRECT was commonality to reduce cost, which is the whole point of the 1.5 architecture.  They pointed out, rightly, that Constellation had thrown out the 1.5 architecture.

It's biggest flaw it was very unimaginative and expensive and inherited all the short comings of the Apollo architecture.

I did not see it that way.  I saw it ignoring all of the benefits of the Apollo architecture.  There were benefits from Apollo, don't forget.  Constellation threw all of those out.

I literally face palmed when I saw Constellation for the first time and knew it was going to fail.

The initial Constellation proposal was not *bad*.  Wasn't good, but not bad.

Space exploration is supposed to develop new technologies if you are afraid to trying anything new as in CxP then you are in the wrong business.

Now we're speaking the same language here.

As for SEP ferries being low risk they are relatively low risk.
DS1 and Smart 1 already proved solar electric to be viable.

Telerobotic operations were proven on on ISS resupply with the ATV and missions like Orbital Express.

Boeing had them as a key part of their architecture.

I consider cryogenic fuel deports even higher risk then SEP tugs but not so high they should be avoided.

But ULA says the near zero boil off technology needed for fuel depots is doable.
They launch rockets for a living and know more on the subject then the designers of the ESAS architecture.

Depends on who you call the designer of the architecture, yes?  Don't forget, ESAS had an EELV 1.5 architecture in there as well.  Studying the EELV form of Constellation, it was incredible how obvious the finger of management was pressing on the scales.

[renclod]

Team direct already showed why the 1.5 architecture was bad and why two smaller HLVs can be better then one monster LV.

"Team Direct" showed nothing of substance against the 1.5 lunar architecture.
When confronted with the shortcomings of their dual launch EOR for lunar cargo, "Team Direct" was inclined to give up on the lunar outpost altogether.
I distinctly remember (and it is burried somewhere in the "Direct" threads, but on record !) Ross posting to the effect that a Moon base is not necessary, after all.

[renclod]

Space exploration is supposed to develop new technologies if you are afraid to trying anything new as in CxP then you are in the wrong business.

On the Moon.
Do the new technologies on the Moon's surface, there's where the action is, not at EML1, not in the Van Allen belts.

Telerobotic operations were proven on on ISS resupply
[...]
I consider cryogenic fuel deports even higher risk then SEP tugs but not so high they should be avoided.

Telerobotics and cryo storage have wide range applications for the lunar outpost. You don't need them in flight, not now, not for lunar.
You need them on the surface.

[Jim]

The 1.5  lunar architecture was poorly implemented.  That is the fact.

[Prober]

Oh yeah, SEP ferries, fuel depots and L1 staging are low risk technologies - if you can talk the Area 51 alliens into paying for it and managing it and bailing it out when in dire need.

 

The Constellation architecture was fundamentally flawed so much so it cause in insurrection among the engineers.

Team direct already showed why the 1.5 architecture was bad and why two smaller HLVs can be better then one monster LV.

It's biggest flaw it was very unimaginative and expensive and inherited all the short comings of the Apollo architecture.

I literally face palmed when I saw Constellation for the first time and knew it was going to fail.

Space exploration is supposed to develop new technologies if you are afraid to trying anything new as in CxP then you are in the wrong business.

As for SEP ferries being low risk they are relatively low risk.
DS1 and Smart 1 already proved solar electric to be viable.

Telerobotic operations were proven on on ISS resupply with the ATV and missions like Orbital Express.

Boeing had them as a key part of their architecture.

I consider cryogenic fuel deports even higher risk then SEP tugs but not so high they should be avoided.

But ULA says the near zero boil off technology needed for fuel depots is doable.
They launch rockets for a living and know more on the subject then the designers of the ESAS architecture.

Couple of thoughts for you.  Aries 1 was to be the quick fix to maintain the space program and the ISS.

Other parts of the program were to save the space program so many of the compaines that might go out of business would have a new project to engineer work for.  2nd part of this was to give out a little seed money to Commercial, not as a replacement but as future support.

The program lost its way.  Timeframe 2008-09 the real design work would be locked down and funded for the Ares V.

[Patchouli]

Telerobotics and cryo storage have wide range applications for the lunar outpost. You don't need them in flight, not now, not for lunar.
You need them on the surface.

For ISRU or an affordable moon base they are a necessity.

Telerobotics can scout out and even set up a an oxygen plant before the first crew ever arrives.

Just a lunox depot on the surface of the moon and EML1 would be a game changer as it would enable reusable landers and ferries in place of a throw away architecture.

[Downix]

Oh yeah, SEP ferries, fuel depots and L1 staging are low risk technologies - if you can talk the Area 51 alliens into paying for it and managing it and bailing it out when in dire need.

 

The Constellation architecture was fundamentally flawed so much so it cause in insurrection among the engineers.

Team direct already showed why the 1.5 architecture was bad and why two smaller HLVs can be better then one monster LV.

It's biggest flaw it was very unimaginative and expensive and inherited all the short comings of the Apollo architecture.

I literally face palmed when I saw Constellation for the first time and knew it was going to fail.

Space exploration is supposed to develop new technologies if you are afraid to trying anything new as in CxP then you are in the wrong business.

As for SEP ferries being low risk they are relatively low risk.
DS1 and Smart 1 already proved solar electric to be viable.

Telerobotic operations were proven on on ISS resupply with the ATV and missions like Orbital Express.

Boeing had them as a key part of their architecture.

I consider cryogenic fuel deports even higher risk then SEP tugs but not so high they should be avoided.

But ULA says the near zero boil off technology needed for fuel depots is doable.
They launch rockets for a living and know more on the subject then the designers of the ESAS architecture.

Couple of thoughts for you.  Ares 1 was to be the quick fix to maintain the space program and the ISS.

Other parts of the program were to save the space program so many of the compaines that might go out of business would have a new project to engineer work for.  2nd part of this was to give out a little seed money to Commercial, not as a replacement but as future support.

The program lost its way.  Timeframe 2008-09 the real design work would be locked down and funded for the Ares V.

You have hit the nail on the head right here.  They lost focus for the whole point of the program.  If they had taken *some* kind of design we had on this thread, or others in ESAS such as LV2, they would have been able to maintain focus.  c'est la vie.

[Downix]

Turns out NASA did actually consider the Lawn Gnome:

http://www.nasaspaceflight.com/2006/07/nasa-has-5-seg-clv-alternatives/

[Prober]

Turns out NASA did actually consider the Lawn Gnome:
 
http://www.nasaspaceflight.com/2006/07/nasa-has-5-seg-clv-alternatives/

now that design i could see

[Jim]

Turns out NASA did actually consider the Lawn Gnome:

http://www.nasaspaceflight.com/2006/07/nasa-has-5-seg-clv-alternatives/

KSC considered it.  It was rejected by the rest of CxP

[Downix]

Turns out NASA did actually consider the Lawn Gnome:

http://www.nasaspaceflight.com/2006/07/nasa-has-5-seg-clv-alternatives/

KSC considered it.  It was rejected by the rest of CxP

Figured.  Would have solved the issues of CxP almost immediately.  So of course, rejection. 

[nethegauner]

A bit older, however.  Here's Rev 3 of the Platypus IIRC

I've seen that picture before, but I never knew there were at least three Platypus designs. Did Rockwell revise it even more before transmitting to the SDIO? Are images of that available somewhere?

I tried to locate information on the Playtypus for a while -- but with no great success (just a report on NTRS with some basic info on two or so pages pages). Even an L2 request did not help.

I've always considered that Platypus thing to be quite an interesting concept. Where would the payload have gone? Right behind the cockpit? How long would the payload bay have been? There does not seem to be much space behind the crew cabin, right?

[Downix]

A bit older, however.  Here's Rev 3 of the Platypus IIRC

I've seen that picture before, but I never knew there were at least three Platypus designs. Did Rockwell revise it even more before transmitting to the SDIO? Are images of that available somewhere?

I tried to locate information on the Playtypus for a while -- but with no great success (just a report on NTRS with some basic info on two or so pages pages). Even an L2 request did not help.

I've always considered that Platypus thing to be quite an interesting concept. Where would the payload have gone? Right behind the cockpit? How long would the payload bay have been? There does not seem to be much space behind the crew cabin, right?

I know up ship has the basic drawings of the layout, because that's where I found mine.  And I had no idea NTRS had any information on it, frankly.

I am uncertain where in the timeline the five different forms were, honestly.  I can see from them a commonality with their X-33 proposal and with the JSC Shuttle II as well.  I still wonder if we'd be ahead if we'd just have used it.

Addendum, found out that there was a book with the details on it, along with other X-33 concepts/SSTO concepts published, "Aerospace Projects Review V1N1" by Scott Lowther.  Google books has it up:
http://books.google.com/books?id=s1Gm0FvRvfEC&pg=PA31&dq=Rockwell+Platypus+SSTO&hl=en&ei=q-X4Td7cNI2ksQO0mMzdBQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCoQ6AEwAA#v=onepage&q=Rockwell%20Platypus%20SSTO&f=false

[nethegauner]

And I had no idea NTRS had any information on it, frankly.

Hidden deep, deep within this study:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940014197_1994014197.pdf

Even includes an operational workflow diagram for the "platypus".

[Downix]

And I had no idea NTRS had any information on it, frankly.

Hidden deep, deep within this study:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940014197_1994014197.pdf

Even includes an operational workflow diagram for the "platypus".

I'd never gotten the numbers on the NLS-3 before.  I knew it was there, but no hard information.  Now it looks pretty clear the similarities between it and the Delta IV.

[luke strawwalker]

Got to pondering a bit more, the twin 2-seg with a new core stage still seems off, it means more development for the program.  Within the RAC-2 studies was one proposal which had Block I as the upper stage w/o the first stage, so, I did a bit of a switcharoo, and instead of developing an AIUS, I had the EDS developed, using the same 8.4m tooling at Michoud as the original plan, added the SRB support beam to the interstage, and viola, we have a core for our twin 2-seg SRB.  To speed up development, I did not use the EDS's new insulation, instead utilizing the existing ET orange thermal protection, so the new insulation would need to be added into development later on.  In addition, the tank is upside down, with the LOX to the front while for EDS it would be to the rear.

This would have been ready to fly in 2008, requiring minimal development.  This could loft up to 30.4 tonnes to the ISS. 

Once the J-2S+ engine was ready, the Block II program begins,  substituting the J-2S+ for the SSME.  This increases the payload to 36 tonnes to the ISS.  When Ares V is ready, swap interstage with one not sporting the SRB support to lighten the load and use the new, non-popcorning insulation, but keep the existing design for crewed launch. 

Consolidation of manufacturing, tooling, and employees makes it more efficient an operation.  This would have reduced the cost to develop the Ares V as well, with the EDS already being 80% completed, and enabled systems testing in the process.  When the 5-segment design for SRB was completed, the 2-segment now becomes the 5-segment with the 3 middle pieces eliminated. It would have fulfilled the ESAS CLV requirements, taken less time and money, and have been ready for flight by the required date.  No long poles, no costly up-front development, none of that.

You know, that vehicle makes a LOT of sense if you HAVE to have SRB's... the single stick version never really made sense without a more powerful and efficient upper stage engine than J-2S,+, or X...

I like the plan to reuse shuttle tank tooling and do a lot of development work on the EDS at the same time, but I think the changes necessary (reversing the LOX tank in the stack, SRB thrust beam, etc.) would have made them two VERY separate beasts indeed...

Not much savings there over AIUS, ESPECIALLY if the AIUS could have indeed been 'shrunk' for use on EELV....

I was always kinda fond of the Stumpy... even this mini-me version of it...  

later!  OL JR

[luke strawwalker]

Ok, proof I am completely bonkers.  In a discussion about dead-ends, the discussion turned to the X-33, and I mentioned how I liked the Rockwell X-33 design due to how pragmatic it was in comparison to the selected Lockheed design.  I them lamented how even then, it still could never be SSTO.  Someone else in the group then popped up "If the point is to be re-usable, why not just re-use the Shuttle SRB? It's already re-usable."  Which then got gears turning.  The ESAS requirement for Ares I was a single SSME and a single 4-segment SRB, so I took the Rockwell X-33, with it's single SSME, cleaned it up for crewed flights, and strapped an SSME to the bottom.

I then crunched the numbers through Schillings, and it would work as an orbital crew vehicle.  It also avoids the pitfall which started the chain of failure with Ares I, that the SSME was too expensive to throw away, and too expensive to make air-startable.  I took the X-33 and Platypus both (all 5 revisions of Platypus at that) and merged their lines with the existing shuttle systems.  I even included an F-111 ejection module that seats 7.

Stupid OCD, 5 hours of my life gone.

I always liked this one myself... use an off-the-shelf SSME, groundlit just like shuttle, enlarge the AIUS for the extra propellant to burn from ground to orbit, use either the 4 segment or 5 segment booster, and you'd have a plenty good enough CLV launcher. 

Before someone says "it'd never work" I beg to differ-- if the shuttle stack can fly, this could too-- heck even model rocket guys are flying stuff like this WITHOUT ACTIVE GUIDANCE using only aerodynamic fins and canting the thrust through the combined stack CG on both motors... including different thrust levels and staging in mid-flight by dropping the booster.  If MODEL ROCKET guys can do it, I KNOW NASA could!!! 

Later!  OL JR

[Silmfeanor]

  If MODEL ROCKET guys can do it, I KNOW NASA could!!! 

Later!  OL JR

These proposals begin to look like abstract art. I like it, though. The Garden Gnome looks better, though. 

How about you add another SRB on the other side, that is airstarted? 

[Jason1701]

That thing must have one heck of a LAS!

[Downix]

Ok, just noticed a slight interesting bit within the Appendix for ESAS.  The LOC is given as 1:1958, but looking at the various parts, it had a LOC for different pieces, and the upper stage had a LOC of 1:911. 

How can a vehicle has a LOC of 1:1958, when one component has a LOC of 1:911?

[renclod]

Ok, just noticed a slight interesting bit within the Appendix for ESAS.  The LOC is given as 1:1958, but looking at the various parts, it had a LOC for different pieces, and the upper stage had a LOC of 1:911. 

How can a vehicle has a LOC of 1:1958, when one component has a LOC of 1:911?

You mean vehicle 14, right ?

LOC (mean) = 1 in 1958

Upperstage engine BGN (benign) failure = 1 in 911

[ Upperstage engine ICF (Instantaneous Catastrophic Failure) = 1 in 7751 ]

911 = number of mean flights between benign failures

[Downix]

Ok, just noticed a slight interesting bit within the Appendix for ESAS.  The LOC is given as 1:1958, but looking at the various parts, it had a LOC for different pieces, and the upper stage had a LOC of 1:911. 

How can a vehicle has a LOC of 1:1958, when one component has a LOC of 1:911?

You mean vehicle 14, right ?

LOC (mean) = 1 in 1958

Upperstage engine BGN (benign) failure = 1 in 911

[ Upperstage engine ICF (Instantaneous Catastrophic Failure) = 1 in 7751 ]

911 = number of mean flights between benign failures

You're right, they did not list this breakdown for the chosen vehicle.

In any case, with a claim of 1905 flights between loss, when there is 911 flights between failures, there is a disconnect in those numbers.