More SRB's?

[SpacemanFL]

I understand the 5 segment SRB's are having trouble with vibration. Another downside is the modifications to infrastructure required for the very tall Ares. Why not add a 3rd or 4th standard SRB to the ET to give it the power required in a Direct 2.0 configuration? Would this stress the ET too much?

[guru]

I understand the 5 segment SRB's are having trouble with vibration. Another downside is the modifications to infrastructure required for the very tall Ares. Why not add a 3rd or 4th standard SRB to the ET to give it the power required in a Direct 2.0 configuration? Would this stress the ET too much?

Not sure about four SRBs, but on another thread,

http://forum.nasaspaceflight.com/index.php?topic=6221.45

Jim basically said that a three SRB configuration would be unworkable due to the difficulty in building a tri-beam configuration to balance the SRB thrust load.

It's actually kind of surprising to see the three SRB configuration come up so much lately.

[gospacex]

Not sure about four SRBs, but on another thread,

http://forum.nasaspaceflight.com/index.php?topic=6221.45

Jim basically said that a three SRB configuration would be unworkable due to the difficulty in building a tri-beam configuration to balance the SRB thrust load.

I don't see why triangular beam configuration won't work. As opposed to Y shaped one - that one is problematic, yes.

Actually, 3- or 4-SRB might move Ares V back in the realm of sanity, provided they already gave up on using existing (underrated for such thrust) flame thenches.

[guru]

Not sure about four SRBs, but on another thread,

http://forum.nasaspaceflight.com/index.php?topic=6221.45

Jim basically said that a three SRB configuration would be unworkable due to the difficulty in building a tri-beam configuration to balance the SRB thrust load.

I don't see why triangular beam configuration won't work. As opposed to Y shaped one - that one is problematic, yes.

Actually, 3- or 4-SRB might move Ares V back in the realm of sanity, provided they already gave up on using existing (underrated for such thrust) flame thenches.

Given that the fueled mass of the Ares V core is almost twice that of a full ET, I think 4 boosters makes sense.  We would still need new infrastructure for all of it, though.

[Stephan]

Would this stress the ET too much?

There is also a mass problem with the crawlerway.
Current "Ares VI" (with 11 segments) is already a bit big, so with 4 standard SRB /16 segments ...

[gospacex]

Would this stress the ET too much?

There is also a mass problem with the crawlerway.
Current "Ares VI" (with 11 segments) is already a bit big, so with 4 standard SRB /16 segments ...

This is not SpaceX thread. We spend taxpayer's money here In this light, strengthening a few miles of crawlerway is not a huge problem.

[Scotty]

One point that is not well known outside the KSC engineering and operations world, there is a sixteen (16) segment limit to the number of segments that can be with in the VAB at any one time.
That limit has to do with the Quanity - Distance / Explosive Equivalancy limitation placed upon the VAB.
In my opinion the number is totally arbitrary and is based on just a judgment call, but it is on the books and has been so for 30 plus years.
To change the segment limit would require a high level NASA manager to "stick his neck out", and I do not see that happening.
So if you did go with three (3), four (4) segment boosters on the Ares V, that would leave you with only a single four (4) segment booster for Ares I

[guru]

One point that is not well known outside the KSC engineering and operations world, there is a sixteen (16) segment limit to the number of segments that can be with in the VAB at any one time.
That limit has to do with the Quanity - Distance / Explosive Equivalancy limitation placed upon the VAB.
In my opinion the number is totally arbitrary and is based on just a judgment call, but it is on the books and has been so for 30 plus years.
To change the segment limit would require a high level NASA manager to "stick his neck out", and I do not see that happening.
So if you did go with three (3), four (4) segment boosters on the Ares V, that would leave you with only a single four (4) segment booster for Ares I

Well that's just enough segments for a Jupiter-120 and a Jupiter-232.  All in favor say "aye".  All right it's settled then. . . well, maybe not yet, but I can wish.

Once/if Ares V is built, there won't be a need for Ares I anymore anyway.  First, it's like a funding placeholder for the SRB and J-2X development.  Second, an Ares megalifter that big could launch both constellation spacecraft and the EDS.  If it's not safe enough for you, though, you could put an uprated EELV through a few hours of testing and manrate that for Orion, thus saving the costs of maintaining the Ares I production line, and probably beat the safety rating at the same time.

[Scotty]

Two 5 1/2 segment Ares V's would be the equivalant of twentytwo (22) segments via my math.
Unless they are going to increase the number of segments allowable with in the VAB at one time, it will be one 5 segment Ares I and a dual 5 1/2 segment Ares V.

[guru]

Two 5 1/2 segment Ares V's would be the equivalant of twentytwo (22) segments via my math.
Unless they are going to increase the number of segments allowable with in the VAB at one time, it will be one 5 segment Ares I and a dual 5 1/2 segment Ares V.

There would only be one 5 1/2 segment Ares V at a time, so 11 segments, plus the five for Ares I, would still only be 16 segments.

[kraisee]

One point that is not well known outside the KSC engineering and operations world, there is a sixteen (16) segment limit to the number of segments that can be with in the VAB at any one time.
That limit has to do with the Quanity - Distance / Explosive Equivalancy limitation placed upon the VAB.
In my opinion the number is totally arbitrary and is based on just a judgment call, but it is on the books and has been so for 30 plus years.
To change the segment limit would require a high level NASA manager to "stick his neck out", and I do not see that happening.

Good point Scotty,

Of course, how they ever plan to launch three or four Ares-V's and an Ares-I back-to-back for the Mars missions then comes into question.

But given that that's a couple of decades away, I guess that'll just be "someone else's problem".


I'd personally change the limit to something like 8 SRB segments maximum per High Bay.   That seems more reasonable to me.   And more logical given we're only really using half the High Bays right now to process Shuttle's.

Ross.

[Antares]

There's this mythical analysis I've heard of from KSC in the 80s or 90s that answers "What if a solid lit off inside the VAB?"  IIRC, the nearest OPF reaches 300 degrees within 90 seconds.  Certainly L2-worthy if it really exists.

[renclod]

One point that is not well known outside the KSC engineering and operations world, there is a sixteen (16) segment limit to the number of segments that can be with in the VAB at any one time.
That limit has to do with the Quanity - Distance / Explosive Equivalancy limitation placed upon the VAB.
In my opinion the number is totally arbitrary and is based on just a judgment call, but it is on the books and has been so for 30 plus years.
To change the segment limit would require a high level NASA manager to "stick his neck out", and I do not see that happening.
So if you did go with three (3), four (4) segment boosters on the Ares V, that would leave you with only a single four (4) segment booster for Ares I

I have posted about the QD limitation in the Direct v2 thread on 5/19. It is interesting how this limitation, if holds, plays into mission planning in a 2-launch architecture versus a 1,5 architecture.

A 1,5 architecture would allow parallel processing in VAB of a lunar cargo mission and a ISS CEV mission. Not possible with a 2-launch a la "Direct".

I am not sure how important this could be for the future, but here you have it.

[kraisee]

There's this mythical analysis I've heard of from KSC in the 80s or 90s that answers "What if a solid lit off inside the VAB?"  IIRC, the nearest OPF reaches 300 degrees within 90 seconds.  Certainly L2-worthy if it really exists.

I've actually seen a copy of that.

It's a lot 'dryer' than you'd imagine.   Just cold hard assessment.

It's got a whole load of different unpleasant scenarios depicted.   Igniters, SRB Sep motors, single segments, partially stacked boosters, fully stacked boosters without the ET, with the ET, with the Orbiter, you name it - they're all in there.

There's analysis of things falling, being knocked over, being hit, lit and generally all the scenario's you don't ever want to hear happening in real life.


Of the "big boom" variety - the Sep motors are apparently more susceptible to a problem than the segments are - but they can trigger the segments in the wrong situations - which can quickly compound the problems.

Igniters thankfully aren't fitted until the stack is at the pad, so aren't a big danger for the VAB, only the Pad.

But if an SRB segment ever lites-up inside the VAB it's going to be a really bad day for anyone inside.   Not really a surprise there.

I'll try to get my friend with that document to send a copy to Chris.

Ross.

[kraisee]

renclod,
Don't forget that a Jupiter-232 can still launch a single-launch Lunar Cargo mission with about 80% the capability of an Ares-V.   Use that, and you could process a Jupiter Lunar cargo and an ISS mission at the same time.

Ross.

[ckiki lwai]

One point that is not well known outside the KSC engineering and operations world, there is a sixteen (16) segment limit to the number of segments that can be with in the VAB at any one time.
That limit has to do with the Quanity - Distance / Explosive Equivalancy limitation placed upon the VAB.
In my opinion the number is totally arbitrary and is based on just a judgment call, ...

16 segments, that's just enough to have 2 shuttle stacks in the VAB.
Could the number be based on this fact?

[kraisee]

I'd say that's why.

I think Scotty's right though - its an arbitrary number which could be changed if a manager wanted to try.

As you say, the number was probably decided because the VAB was setup to process a maximum of 2 Shuttle's at a time - and to reduce the risk it was decided that only sufficient segments for those two stacks should be in there at the same time - with all others stored off-site until required.

A sensible idea, but one which does need reviewing if you ever open up a third (or fourth) High Bay for stacking operations.


And actually - there is a theoretical scenario right now where they could theoretically have 24 segments in there at one time.   If one stack were at the Pad and two others were in various stages of being prepared for flight in the VAB (16 segments) - what would happen if a hurricane blows into town?    The stack at the Pad would have to be rolled back into the safe haven High Bay, no?

Theoretically you could thus end up with 24 SRB segments inside the VAB at one time in such a situation - 8 in HB1, 8 in HB3 and 8 in HB2.   I'm sure there's some sort of waiver procedure for such a case though...

Ross.

[Eerie]

Can someone explain why it is impossible to bring SRBs to the launch pad separately?

[nacnud]

Because you'd need some form of magic to hold the rest of the stack up.

[Eerie]

Because you'd need some form of magic to hold the rest of the stack up.

Can you hold it with something else... less heavy?