Author Topic: A Matter of Height  (Read 18046 times)

Offline Steven Pietrobon

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A Matter of Height
« on: 09/07/2014 06:35 AM »
Hey folks. For the last few months I've been working on a Lunar mission using a single SLS. This uses two RSRMV boosters, six engine RS-25E core, dual J-2X upper stage and quad RL-10C-2 cryogenic propulsion stage which performs TLI, LLO and 75% powered descent. The Lunar lander does the remaining descent and takes off again using the same engines, leaving the landing and cargo module behind.

However, I've come up with a big problem. The damn thing is too tall. According to

NASA, "Space Launch System Program (SLSP) logistics support analysis (LSA) report," SLS-RPT-108 Version 1, Apr. 2013.

SLS is limited to a height of 118.87 m. I have assume that's the height from the bottom of the RS-25 engines to the tip of the launch abort system. However, my vehicle design comes in at 122.6 m, a matter of being 3.73 m too tall! I've already used common bulkheads in the US and CPS.

I'm reaching out to member of NSF for ideas of how to make this fit. Are my assumptions for the height restriction correct? Any ideas or new information you can contribute would be greatly appreciated. Thanks.

Attached are my preliminary drawings plus where I have my paper at the moment (its about half way done).
« Last Edit: 09/07/2014 06:39 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline MP99

« Last Edit: 09/07/2014 11:21 AM by Chris Bergin »

Offline spectre9

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Re: A Matter of Height
« Reply #2 on: 09/07/2014 07:11 AM »
I found a document that says "all dimensions measured from nozzle exit plane".

From what I understand the length of the Block II payload fairing isn't set in stone.

Offline Steven Pietrobon

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Re: A Matter of Height
« Reply #3 on: 09/07/2014 07:12 AM »
Yes, that would help a lot. We could also avoid common bulkheads. The problem is that MLAS needs to be fully developed.

Thanks spectre9.
« Last Edit: 09/07/2014 07:19 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline German Space Fan

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Re: A Matter of Height
« Reply #4 on: 09/07/2014 07:16 AM »
Hey folks. For the last few months I've been working on a Lunar mission using a single SLS. This uses two RSRMV boosters, six engine RS-25E core, dual J-2X upper stage and quad RL-10C-2 cryogenic propulsion stage which performs TLI, LLO and 75% powered descent. The Lunar lander does the remaining descent and takes off again using the same engines, leaving the landing and cargo module behind.


Oh my goodness. :o How much payload would this SLS be able to send to moon? I think the 4*RL-10 Stage is not necessary. The J2-X stage does TLI, a big lunar lander similar to Altair does LLO and descent. We replace the RSMRVs with advanced boosters -Batman should be strong enough- and then we hope this works.

Offline libs0n

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Re: A Matter of Height
« Reply #5 on: 09/07/2014 07:24 AM »
Launch with no abort system at all.

Offline Steven Pietrobon

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Re: A Matter of Height
« Reply #6 on: 09/07/2014 07:26 AM »
Oh my goodness. :o How much payload would this SLS be able to send to moon?

TLI is  67,452 kg, but that includes the 10,501 kg CPS.

Quote
I think the 4*RL-10 Stage is not necessary. The J2-X stage does TLI, a big lunar lander similar to Altair does LLO and descent. We replace the RSMRVs with advanced boosters -Batman should be strong enough- and then we hope this works.

That means the US does a 6 km/s burn instead of 3 km/s with less efficient engines. The Altair descent stage also has a dry mass of about 10 t, the same as the CPS. This results in significantly worse performance. We need four RL-10 engines, otherwise the gravity loss is too high for TLI. This is really fine balancing act. One wrong move and it doesn't work.
« Last Edit: 09/07/2014 07:28 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Steven Pietrobon

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Re: A Matter of Height
« Reply #7 on: 09/07/2014 07:27 AM »
Launch with no abort system at all.

Great out of the box thinking there! You could only do that without the crew, which means a second launch. I'm going for an Apollo style all-in-one mission.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Steven Pietrobon

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Re: A Matter of Height
« Reply #8 on: 09/07/2014 07:35 AM »
Thanks for your comments guys. I'm starting to think that MLAS is the least bad solution.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline libs0n

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Re: A Matter of Height
« Reply #9 on: 09/07/2014 07:37 AM »
Launch with no abort system at all.

Great out of the box thinking there! You could only do that without the crew, which means a second launch. I'm going for an Apollo style all-in-one mission.

No, I mean with the crew.  Shuttle had dozens of no LAS flights after Challenger.  Columbia was heat shield damage that isn't applicable here, and they still put crews on it afterward, and there was plenty of clamoring for even more.

LAS protects against a small minority of mission length during an inherently dangerous mission whose danger must be accepted.  A small uptick in risk.  You simply have to subjectively decide whether you find that tolerable or not.  It's still an option.

edit: small payload bonus too
« Last Edit: 09/07/2014 07:38 AM by libs0n »

Offline M129K

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Re: A Matter of Height
« Reply #10 on: 09/07/2014 08:36 AM »
Has it ever been considered to replace the AJ-10 on Orion with a more powerful engine for abort, and performing in-space maneauvres with the 8 smaller backup engines? It wouldn't be as capable of a full fledged abort system but would greatly increase the range in which Orion can abort on its own without LAS. It would be a bit of a compromise.

Online KelvinZero

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Re: A Matter of Height
« Reply #11 on: 09/07/2014 11:41 AM »
Send a Dragon V2 instead. It is stubby.

Sorry, Im sure that is not remotely helpful but someone was bound to say it :)

Offline mike robel

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Re: A Matter of Height
« Reply #12 on: 09/07/2014 01:54 PM »
Change to a direct throw to the moon surface?

Offline M129K

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Re: A Matter of Height
« Reply #13 on: 09/07/2014 02:35 PM »
Change to a direct throw to the moon surface?
Going with a direct approach like FLO might have some advantages to "simplicity" but does of course result in a huge increase in mass.

If you take an Orion CM of 10.4 tons, a storable propellant descent and return module with 3300 m/s ∆V (500 for terminal descent, 1900 for ascent and 900 for return) with 324 second Isp, a LOI/crasher stage with 2400 m/s ∆V and 465 second Isp and a TLI stage, with 3150 m/s ∆V and 465s Isp, all with 0.9 PMF, you get a total mass in LEO of >150 metric tons. It's not impossible to do, but it would require a five engine core+large RP-1 boosters and super sized upper stage, plus three unique in-space stages. Unless you park some fuel for the vehicle in elliptical lunar orbit (which would kind of take away the point of Steven's architecture) it wouldn't be realistically doable with SLS.

Online RonM

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Re: A Matter of Height
« Reply #14 on: 09/07/2014 03:02 PM »
This is a tricky problem. You can see why Constellation went with the 1.5 architecture. It would be a lot easier to do this if Orion was smaller and could be launched from a EELV.

As to the height issue, obviously the LAS is the problem. Perhaps engines for launch abort could be added to the Command Module. If these engines were used for part of the burn to head back to Earth, then it wouldn't be a waste of mass dragging them around after launch.

Offline Rocket Science

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Re: A Matter of Height
« Reply #15 on: 09/07/2014 03:13 PM »
You might think along the lines of a modified Boeing CST-100 LES...Or as I suggested in the "SLS looking for missions thread" modify CST-100 complete for BEO with heatshield upgrade...
« Last Edit: 09/07/2014 03:17 PM by Rocket Science »
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Offline dglow

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Re: A Matter of Height
« Reply #16 on: 09/07/2014 04:32 PM »
Grow the VAB?

Offline M129K

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Re: A Matter of Height
« Reply #17 on: 09/07/2014 04:33 PM »
Yeah, I'm also wondering if moving up the door a little wouldn't be cheaper than modifying the whole architecture.

Offline Verio Fryar

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Re: A Matter of Height
« Reply #18 on: 09/07/2014 04:54 PM »
Since you are not using the SLS core why not just make it wider?
A 6 engine core is not and will not be part of SLS, and probably neither a three stage plus boosters.

Offline MP99

Re: A Matter of Height
« Reply #19 on: 09/07/2014 05:46 PM »


Yes, that would help a lot. We could also avoid common bulkheads. The problem is that MLAS needs to be fully developed.

Thanks spectre9.



Thanks for your comments guys. I'm starting to think that MLAS is the least bad solution.

0) One or two RS-25 on the u/s instead of J2.

OK, alternative suggestion.

Move u/s O2 tank above the H2 tank, and somehow wrap it around the CPS's RL10s.

1) build into the interstage as an annulus / torus.

2) make the LOX tank out of two inward-facing domes. The RL10s would sit within the downward facing dome. I appreciate that there is a mass penalty for that inward-facing dome that isn't supported by pressure on its other face.

Wilder:-

3) put all the LOX for both u/s & CPS in the CPS, and downfeed it to the u/s. The mass penalty to the LOX tank should just be limited to barrel stretch, so relatively small, but there would also be hardware for the LOX transfer itself. Biggest challenge is to maximise the amount of transfer hardware which can be discarded post SECO.

Note, though, that Shuttle managed to do this cleanly 134 times post MECO. I believe they left a ten second gap before ET separation, which ISTM would not be any real penalty for your trajectory design. Of course, the advantage is that this isn't done under the time pressure you'd experience during ascent. Ten seconds, or even 60 seconds, shouldn't really matter? [Note that Congress wanted NASA to reuse Shuttle tech in SLS :-) ]

Ridiculously wild:-

4) integrate both stages. Launch with both J2s & RL10s on that combined stage. Burn J2 during ascent, and drop post SECO.

4a) "After 1.8s, the CPS fires to circularise the orbit."

Note that you could terminate the J2s during ascent at the point where Isp overtakes gravity losses in importance, then drop them and do one continuous RL10 burn that completes both your ascent burn, plus the circularisation. RL10s then perform both third stage + EDS, just like Saturn V. Same number of separation events as your trajectory design, just that you're dropping engines instead of full-stage staging.

Ratcheting up the wildness even more:-

4b) As 4a, but burn both J2 & RL10 during ascent, and drop the J2's partway through ascent, at the point where they become a liability . (This may even allow you to get away with a single J2?

Some variants of Atlas first stage used a sustainer, and dropped engines partway through the burn.

Super-ridiculous:-

4b) as 4a, but drop tank for the H2 burned during ascent.

Having trouble coming up with a (5)...



Back to not-so-silly. Use J2 for ascent + TLI, just like Ares V. Use drop tanks to feed storable prop to the ascender stage, and discard just before the landing.

Trade dry mass for Isp.

Cheers, Martin

Offline arachnitect

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Re: A Matter of Height
« Reply #20 on: 09/07/2014 06:14 PM »
The whole idea seems to be a one launch lunar mission, so you're not gonna want to hear my suggestions.

Just out of curiosity, why are you trying to do the mission in one launch?

Yeah, I'm also wondering if moving up the door a little wouldn't be cheaper than modifying the whole architecture.

Is it just the door mechanism that's in the way or is there roof structure behind the door that the stack can't clear?

Offline Herb Schaltegger

Re: A Matter of Height
« Reply #21 on: 09/07/2014 07:24 PM »
Yes, that would help a lot. We could also avoid common bulkheads. The problem is that MLAS needs to be fully developed.

Sure. But so, too, do your 6 engine first stage, 2 engine second stage and your entire lander. I'd think once you're going THAT far, what's a bit more effort for the MLAS? I mean, seriously ...
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Offline Burninate

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Re: A Matter of Height
« Reply #22 on: 09/07/2014 07:43 PM »
1) Is post-rollout integration of the LAS itself, from a crane in the open air, feasible?

2) "This results in significantly worse performance. We need four RL-10 engines, otherwise the gravity loss is too high for TLI. "

Have you considered a two-orbit or three-orbit, split TLI burn?  Less TWR needed, at the cost of some additional Van Allen Belt exposure, and less gravity loss.

Something along the lines of: A) Liftoff to LEO, B) LEO to GTO, C) inclination correction to correct plane near lunar orbit, D) GTO to TLI

3)
Yeah, I'm also wondering if moving up the door a little wouldn't be cheaper than modifying the whole architecture.

Myself as well.  That door has already been brought up as limiting launch vehicle integration methodologies to a certain width - and IMO if it's doing that, it's not doing its job of being a door.

Constructing a building of this scale is relatively expensive, but much less expensive than the average manned exploration mission.  The Aerium airship hangar, while not designed for rockets, is one example of recent construction of somewhat larger than this volume, and it cost around $100M to build.  Inflate that arbitrarily to, say, $1B, and it still looks pretty reasonable if it lets you use cheaper / already-designed rockets in a series of exploration missions.
« Last Edit: 09/07/2014 09:17 PM by Burninate »

Offline floss

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Re: A Matter of Height
« Reply #23 on: 09/07/2014 09:08 PM »
A moblie gantry would be pretty cost effictive seeing as it is only a shed with a crane .It would be even better if you could remove the payload if safety concerns delay the rocket.

Offline sdsds

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Re: A Matter of Height
« Reply #24 on: 09/07/2014 10:24 PM »
1) Is post-rollout integration of the LAS itself, from a crane in the open air, feasible?

Wow! It breaks the concept of LC-39 operations, but ... yeah. Were you imagining integration of the LAS just outside the VAB, or at the pad?
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Offline Burninate

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Re: A Matter of Height
« Reply #25 on: 09/07/2014 11:08 PM »
1) Is post-rollout integration of the LAS itself, from a crane in the open air, feasible?

Wow! It breaks the concept of LC-39 operations, but ... yeah. Were you imagining integration of the LAS just outside the VAB, or at the pad?

Either-or, it's just a matter of the easiest place to have the crane.  An external LAS is a very tall, skinny, lightweight feature - putting it on outside the VAB allows for a lot of literal headroom.  If you want to get inventive, it's also plausibly lightweight enough to apply by helicopter at the pad, with locking mechanisms engaged at the level of the crew loading mechanism (though I'm not sure that makes any sense from a safety perspective).

In a long-run concern, you might also plausibly improve the safety of the whole system, because in the event that a liquid booster is ever approved for the SLS, they can eliminate solids from the building entirely - perhaps even equip the LAS after crew loading for minimum risk surface.

Offline Lars_J

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Re: A Matter of Height
« Reply #26 on: 09/07/2014 11:22 PM »
Yes, that would help a lot. We could also avoid common bulkheads. The problem is that MLAS needs to be fully developed.

I keep being mystified regarding the aversion to common bulkheads. It was done 45 years ago for LOX/LH2, and at 10m diameter even. So why?

Offline jg

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Re: A Matter of Height
« Reply #27 on: 09/07/2014 11:38 PM »
There is a nice movie about the Saturn V stage w. common bulkhead.  LH2 is so cold it would freeze the LOX.  Doing the insulation was a PITA...

Offline sdsds

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Re: A Matter of Height
« Reply #28 on: 09/08/2014 01:00 AM »
Doing the [common bulkhead] insulation was a PITA...

Yes but, "No pain, no gain," and to do the trade requires quantifying both the pain and the gain in terms of both dollars and schedule.

I keep being mystified regarding the aversion to common bulkheads. It was done 45 years ago for LOX/LH2, and at 10m diameter even. So why?

Do you mean for upper stages, or boosters? For the SLS core I'm pretty sure the decision was based on schedule. The core found itself on the critical path. Separate tanks meant essentially zero schedule risk....
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Offline arachnitect

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Re: A Matter of Height
« Reply #29 on: 09/08/2014 01:33 AM »
For the SLS core I'm pretty sure the decision was based on schedule. The core found itself on the critical path. Separate tanks meant essentially zero schedule risk....

putting the thrust beam anywhere else [i.e. not in the intertank] would be a nightmare.
« Last Edit: 09/08/2014 01:33 AM by arachnitect »

Offline mike robel

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Re: A Matter of Height
« Reply #30 on: 09/08/2014 01:34 AM »
For the larger Saturn variants, NASA did consider a crane just outside the door to lift the spacecraft onto the booster.  might be tricky in bad weather

Offline Lars_J

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Re: A Matter of Height
« Reply #31 on: 09/08/2014 02:14 AM »

I keep being mystified regarding the aversion to common bulkheads. It was done 45 years ago for LOX/LH2, and at 10m diameter even. So why?

Do you mean for upper stages, or boosters? For the SLS core I'm pretty sure the decision was based on schedule. The core found itself on the critical path. Separate tanks meant essentially zero schedule risk....

Just the upper stage(s). The SRB thrust beam makes an SLS core common bulkhead a tricky thing. But there is no reason why an upper stage can't have it.

Offline Lars_J

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A Matter of Height
« Reply #32 on: 09/08/2014 02:17 AM »
There is a nice movie about the Saturn V stage w. common bulkhead.  LH2 is so cold it would freeze the LOX.  Doing the insulation was a PITA...

Yes, it wasn't easy, but that is no reason to throw your hands up essentially saying "can't be done!". It HAS been done. It isn't impossible. The reluctance to even contemplate it reminds me of this scene from "Iron man":

« Last Edit: 09/08/2014 02:19 AM by Lars_J »

Offline jg

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Re: A Matter of Height
« Reply #33 on: 09/08/2014 04:14 AM »
Doing the [common bulkhead] insulation was a PITA...

Yes but, "No pain, no gain," and to do the trade requires quantifying both the pain and the gain in terms of both dollars and schedule.

The reason why they bothered was that the LEM+Apollo capsule got heaver than expected, and they could not redesign everything; the weight had to be saved somewhere.  That happened to be the SII second stage.  There are easier ways to get the 7900lb's saved.

The only people they could find who could do the insulation work successfully were surfers who had been working on building surf boards; the problem was that if the surf was up, they'd lose schedule, as their workforce would head for the waves!

Offline Steven Pietrobon

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Re: A Matter of Height
« Reply #34 on: 09/08/2014 06:32 AM »
Since you are not using the SLS core why not just make it wider?

Yes, that might work, but it also means that a new MLP is needed. I'm trying to use as much of the existing core as possible.

0) One or two RS-25 on the u/s instead of J2.

The RS-25 is about the same height as J-2X, so I don't think that helps much.

Quote
Move u/s O2 tank above the H2 tank, and somehow wrap it around the CPS's RL10s.

Good idea, but I believe the four RL-10's take up too much room.

Just out of curiosity, why are you trying to do the mission in one launch?

Yes. I think that's the way that has the greatest chance of success.

Yes, that would help a lot. We could also avoid common bulkheads. The problem is that MLAS needs to be fully developed.
Sure. But so, too, do your 6 engine first stage, 2 engine second stage and your entire lander. I'd think once you're going THAT far, what's a bit more effort for the MLAS? I mean, seriously ...

Which is why I've decided to use MLAS in the baseline configuration. I would have preferred not too, but it seems to be the best solution to the problem. It also avoids using common bulkheads and using existing US and CPS designs from Boeing and NASA.

I keep being mystified regarding the aversion to common bulkheads. It was done 45 years ago for LOX/LH2, and at 10m diameter even. So why?

The experience with S-II put a lot of people at NASA off the idea of common bulkheads. It is seen as expensive and time consuming. However, with modern tooling I would think it is now much easier to do. In fact, I was all ready to use common bulkheads, but I was still left with the vehicle being 3.7 too high. Had the vehicle met the height limitation, I would have gone with common bulkheads.

Thankyou everyone for your ideas.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline MP99

Re: A Matter of Height
« Reply #35 on: 09/08/2014 07:03 AM »


Doing the [common bulkhead] insulation was a PITA...

Yes but, "No pain, no gain," and to do the trade requires quantifying both the pain and the gain in terms of both dollars and schedule.

The reason why they bothered was that the LEM+Apollo capsule got heaver than expected, and they could not redesign everything; the weight had to be saved somewhere.  That happened to be the SII second stage.  There are easier ways to get the 7900lb's saved.

The only people they could find who could do the insulation work successfully were surfers who had been working on building surf boards; the problem was that if the surf was up, they'd lose schedule, as their workforce would head for the waves!

Is ULA's solution to this any simpler?

Dual layer dome with small void filled with CO2. Freezes out as soon as cryos are loaded into the tank above, instant vacuum insulator.

Cheers, Martin

Offline MP99

Re: A Matter of Height
« Reply #36 on: 09/08/2014 07:06 AM »


0) One or two RS-25 on the u/s instead of J2.

The RS-25 is about the same height as J-2X, so I don't think that helps much.

I was assuming that the higher Isp would reduce tank size a bit. But no, I can see now, not enough to help.

Cheers, Martin

Offline Nibb31

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Re: A Matter of Height
« Reply #37 on: 09/08/2014 08:35 AM »
Couldn't the height of Orion be reduced by redesigning its service module? The narrow design makes it tall. Make the width of the SM match the diameter of the CM, like on the CST-100, and it will be significantly shorter.

Offline spacenut

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Re: A Matter of Height
« Reply #38 on: 09/08/2014 03:06 PM »
Common bulkheads would work great with methane/oxygen since their liquid point is only a few degrees apart.  That way they could also use the same pumps, fittings, valves, etc.  Shorter overall stack with each stage.  I think this is what Space-X is trying to do with their Raptor engine and future 10m large rocket. 

Offline Ronpur50

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Re: A Matter of Height
« Reply #39 on: 09/08/2014 04:00 PM »
1) Is post-rollout integration of the LAS itself, from a crane in the open air, feasible?

Could it be done the same way the lighting mast was added to the top of the MLP tower for the Apollo Soyuz Saturn 1B?  It was attached from a structure added to the top of the VAB over the door.

Offline TomH

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Re: A Matter of Height
« Reply #40 on: 09/09/2014 01:48 AM »
This illustrates the importance of high ISP density fuel and massive thrust at launch. Part of the problem is lack of hydrocarbon fuel at launch.

Hate to say it, but von Braun nailed it with Saturn V. For what you want on SLS the easiest method is 5.5 m Kerolox boosters using two F-1B or 6-8 of that engine AJ recently announced that's basically half of an AJ-1E6. That one change, ISTM, would be much easier and less costly than all these other deviations from the current plan. Then again, I've heard a bit about a 10-15m 9 engine methane monster lately as well.
« Last Edit: 09/09/2014 04:08 AM by TomH »

Offline Steven Pietrobon

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Re: A Matter of Height
« Reply #41 on: 09/09/2014 05:01 AM »
Could it be done the same way the lighting mast was added to the top of the MLP tower for the Apollo Soyuz Saturn 1B?  It was attached from a structure added to the top of the VAB over the door.

Never knew that. It looks like that structure has been removed, but it could be added back again I suppose. Interesting idea!

Perhaps the LAS could be installed with a hinge on one side. The vehicle is moved out with the LAS pointed down. The LAS is then lifted and locked into place outside the VAB doors. This could be a scheme that might work.
« Last Edit: 09/09/2014 05:05 AM by Steven Pietrobon »
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Offline aero

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Re: A Matter of Height
« Reply #42 on: 09/09/2014 06:37 AM »
Take a page from the shuttle. Make the first stage shorter, then add drop tanks to make up the prop shortage.
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Re: A Matter of Height
« Reply #43 on: 09/09/2014 07:45 AM »
putting the thrust beam anywhere else [i.e. not in the intertank] would be a nightmare.

Ah yes of course, thanks.

As regards the in-space (i.e. non-SLS) elements of the mission as described in the pdf, my major concern is with whether the CPS as described might become "a bridge too far" (vaguely in the Operation Market Garden sense). The mission requires the CPS to provide hydrolox propulsion many days after launch. Yes, this was exactly the plan for CxP with Altair. But how well did that really work out? ;)

I'm personally not concerned about the dollar cost of developing the CPS, but the risks involved seem quite high. There is schedule risk, since the TRL isn't all that high and there might be unknown uknowns. There's program risk, in the sense that one of those unknowns might be difficult to overcome even with extra time and dollars thrown at it. And then there's mission risk: the technology might pass tests but fail when used for an actual mission.

I just don't see how an element like that can get developed at the same time as the lander element and possibly also the Large Upper Stage element. Is there any way to complete the CPS and validate it on an earlier, simpler mission?

For example, could the CPS functionality be validated on a mission that did not include either the lander or the LUS, but which nonetheless did something useful? What is the payload into DRO of a stack that consists of a Block 1 SLS with a CPS sized to meet the lunar mission's needs on top? Would it be enough for an Orion and a large space station module?
« Last Edit: 09/09/2014 07:48 AM by sdsds »
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Offline Jim

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Re: A Matter of Height
« Reply #44 on: 09/09/2014 07:51 AM »

Which is why I've decided to use MLAS in the baseline configuration.
Better off changing the SM to provide abort much like CST-100 or DragonRider.

MLAS is not a viable system.  The test that was performed was nothing like the system that would be needed.

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Re: A Matter of Height
« Reply #45 on: 09/10/2014 02:13 PM »
Yeah, I'm also wondering if moving up the door a little wouldn't be cheaper than modifying the whole architecture.
That would be difficult, the VAB doors(VLD's-Vertical Lift Doors) are quite complicated so far as doors are concerned. Each opening is 139 meters (456 ft) high


Video of door operation.
http://archive.org/details/VabDoorsOpeningWithTimeLapse

Block II crewed SLS will be 385 tall,whereas Saturn V was 363 ft tall.  The MLP is 20ft tall, and teh Crawler Transporter has a variable height range from 20-26ft.
TYhe MLP is set atop six stationary legs emasuring 22"ft tall.
The Apollo Saturn V Launch Umbilical Towers LUTs) were 380ft tall.
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Offline Lobo

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Re: A Matter of Height
« Reply #46 on: 09/10/2014 04:20 PM »
Hey folks. For the last few months I've been working on a Lunar mission using a single SLS. This uses two RSRMV boosters, six engine RS-25E core, dual J-2X upper stage and quad RL-10C-2 cryogenic propulsion stage which performs TLI, LLO and 75% powered descent. The Lunar lander does the remaining descent and takes off again using the same engines, leaving the landing and cargo module behind.

However, I've come up with a big problem. The damn thing is too tall. According to

NASA, "Space Launch System Program (SLSP) logistics support analysis (LSA) report," SLS-RPT-108 Version 1, Apr. 2013.

SLS is limited to a height of 118.87 m. I have assume that's the height from the bottom of the RS-25 engines to the tip of the launch abort system. However, my vehicle design comes in at 122.6 m, a matter of being 3.73 m too tall! I've already used common bulkheads in the US and CPS.

I'm reaching out to member of NSF for ideas of how to make this fit. Are my assumptions for the height restriction correct? Any ideas or new information you can contribute would be greatly appreciated. Thanks.

Attached are my preliminary drawings plus where I have my paper at the moment (its about half way done).

Steve,

Can you integrate the 2nd stage and CPS into a single 8.4m wide stage and power it with MB-60's?  Make a bigger JUS out of it essentially.
Obviously that's an engine NASA was/is considering for SLS's EUS anyway, so it's not outside any realm of possibility.  I think JAXA is pursuing it for their next generation LV, which was why NASA was considering it.  (I think the possibility of moving the EUS up to like the 2nd SLS mission is or has moved them to four RL-10's though). 

Direct determined that six RL-10B's could fit under the 8.4m JUS.  The MB-60 would be the same size as the RL-10B, so you should be able to fit 6 of them under there.  It's not as much thrust as two J2X, but more ISP. 

That would two a couple of things.  First it should shorten your stack enough to fit in the VAB.  Secondly it means just one new upper stage (in place of the EUS) development rather than two.  Thirdly it would simplify umbilicals as there's only two cryo stages rather than 3.  Fourth, the stack uses just two engines rather than 3. 

Developing MLAS is a possibility, but rather since Orion doesn't have a SM yet, have a redesing of it to borrow from the CST-100 concept and create a pusher LAS sytem using the SM propellants for abort.  If there is no abort, they will provide the dV for th CSM to break lunar orbit and come up.  A better way to go anyway, than lugging separate LAS solid propellant up as well as the SM storable propellant. 
That could use RS-88's, or perhaps some large hypergolic engine if there was one that could be easily developed or modified, like a heavily modified LR91 or something...although the potential problem there is can such a powerful engine throttle down enough to be a feasible OMS engine for the CSM if not used for abort?  So a cluster of smaller engines like RS-88's might be better.  Where a cluster of say 5 engines on the SM could be used for abort, but just the central engine used for the TEI burn.
Even MLAS means SLS must carry both LAS propellant mass and SM propellant mass uphill.  And the MLAS, like the tractor tower, but separate every mission, or there will be a LOM.  ANd it's only carried part way to orbit.  As Elon's fond of pointing out, and integrated pusher system could abort from anywhere during ascent. 


Offline Lobo

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Re: A Matter of Height
« Reply #47 on: 09/10/2014 10:30 PM »
This illustrates the importance of high ISP density fuel and massive thrust at launch. Part of the problem is lack of hydrocarbon fuel at launch.

Hate to say it, but von Braun nailed it with Saturn V. For what you want on SLS the easiest method is 5.5 m Kerolox boosters using two F-1B or 6-8 of that engine AJ recently announced that's basically half of an AJ-1E6. That one change, ISTM, would be much easier and less costly than all these other deviations from the current plan. Then again, I've heard a bit about a 10-15m 9 engine methane monster lately as well.

Yea, I agreed.

But I think Steve's point would be once RAC-1 was chosen in 2011, was there perhaps a little better way to do it that'd get the 130mt for less money?  Assuming they could keep making steel booster casings, there's be no need for any new boosters, so had it been chosen right out of the gate, we'd not need to be messing with new bosoters.
I think money could be saved with an MB-60 powered "JUS" single upper stage/EDS/crasher stage rather than a J2X powered upper stage and RL-10 CPS, if six MB-60's would have enough thrust.  (Without nozzle extensions, 7 could fit, but there'd be a hit in ISP in space).

Ultimately, RAC-2 won the RAC competition in every area but politics.  And I think it wouldn't have needed J2X.  They could have borrowed a page from SpaceX.  Have like nine TR-107's on the booster and one air-lit vacuum version to get into disposal orbit.  Both stages would be the same diameter and use the same tooling to make.  With two kerolox stages, that helps with propellant density, and the SC TR-107 would have good vacuum ISP.
Then put your ultra-light hydrolox CPS/EDS on top of it powered by RL-10B's, and have it double as your crasher stage for your lander.  It could be common bulkhead like the JUS and use the same 8.4m tooling as well.
Even at 8.4m rather than 10m, this LV should fit within the VAB and have over 130mt to LEO capacity.  Only one new engine development, and it was already partially developed a decade before.  and all stages made on the new set of 8.4m core tooling at MAF.

Offline Steven Pietrobon

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Re: A Matter of Height
« Reply #48 on: 09/11/2014 09:19 AM »
Can you integrate the 2nd stage and CPS into a single 8.4m wide stage and power it with MB-60's?

You could, but then it won't work. You'll be carrying a 30 t dry mass to 500 m/s off the Lunar surface instead of 10 t. Total delta-V would be equivalent to 8 km/s which is just too big. I split this into 3 and 5 km/s.
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Offline spectre9

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Re: A Matter of Height
« Reply #49 on: 09/11/2014 01:10 PM »
Should have built a 10m tank.

Oh how it has pained me watching them build all new everything down at Michoud for the good old 8.4m tank just to keep up the appearance of "shuttle derived".  ::)

Wider tanks means height concerns are less. You can get a 200mt vehicle at 400ft.

Offline mike robel

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Re: A Matter of Height
« Reply #50 on: 09/11/2014 03:10 PM »
And, gee, you know.  It's not like, well, a 10M tank was never built by anyone before.  Seemed to work pretty good, you know.  Just saying.

Offline JasonAW3

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Re: A Matter of Height
« Reply #51 on: 09/11/2014 03:49 PM »
Hey folks. For the last few months I've been working on a Lunar mission using a single SLS. This uses two RSRMV boosters, six engine RS-25E core, dual J-2X upper stage and quad RL-10C-2 cryogenic propulsion stage which performs TLI, LLO and 75% powered descent. The Lunar lander does the remaining descent and takes off again using the same engines, leaving the landing and cargo module behind.

However, I've come up with a big problem. The damn thing is too tall. According to

NASA, "Space Launch System Program (SLSP) logistics support analysis (LSA) report," SLS-RPT-108 Version 1, Apr. 2013.

SLS is limited to a height of 118.87 m. I have assume that's the height from the bottom of the RS-25 engines to the tip of the launch abort system. However, my vehicle design comes in at 122.6 m, a matter of being 3.73 m too tall! I've already used common bulkheads in the US and CPS.

I'm reaching out to member of NSF for ideas of how to make this fit. Are my assumptions for the height restriction correct? Any ideas or new information you can contribute would be greatly appreciated. Thanks.

Attached are my preliminary drawings plus where I have my paper at the moment (its about half way done).

You might want to consider using a "pusher"abort system that could be mounted under the main capsule, or possibly around the service module, until it could be discarded.  (Likely a 4 petal affair, similar to outer coverings being released).  This would significantly reduce your overall height, increase the safe abort envelope and stay within both your mass and heighth limitations.
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Offline JasonAW3

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Re: A Matter of Height
« Reply #52 on: 09/11/2014 03:52 PM »
Grow the VAB?

Probably cheaper to simply build a whole new VAB, like they intended to with the Nova rockets.
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Offline M129K

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Re: A Matter of Height
« Reply #53 on: 09/11/2014 04:50 PM »
Steven, I read your paper and I noticed that you assumed the mass of Orion is 22.2 metric tons. Now, I don't want to force you to throw over your whole architecture, but this recent fact sheet released on the NASA website puts the total mass of Orion at 26.5 metric tons, and the mass without fuel at 17.2. The ∆V of the vehicle is 1340 m/s which implies a 316 s specific impulse (which is inline with the Space Shuttle OMS engine supposed to be used on the vehicle). Link. I've been told that these numbers include a healthy dose of margin but it's nonetheless significantly higher than 22.2 tons, a mass at which Orion would only be capable of 791 m/s.

As has been said a lot of times in this thread before, replacing the OMS engine on the ESM with a (cluster of) more powerful storable propellant engines with a total thrust on the order of >1000kN (perhaps provided by five or six RS-88 class engines) would provide it with a lot of abort capability with reduced height. The smaller R-4D backup engines would still be able to provide ~1300 m/s, enough for lunar return.

Offline simcosmos

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Re: A Matter of Height
« Reply #54 on: 09/11/2014 05:46 PM »
M129K, thanks for the link to that Orion's fact sheet: from quite some time now that I was curious about updated info on Orion's mass breakout.

The CM growth was something I was expecting but the SM numbers... Hummmmm... I would still need to study the file  a bit better but that SM is experiencing quite a mass jump!!!

I will perhaps post some thoughts about this issue in another (more specific, already existing = EDIT: please click here) thread but for now will only write that the ~26.5t (I got ~26.36t when doing the math on the pdf's available info) seems to be the injected mass, I mean, for Orion burns we need to subtract the mass of the adapter (Orion mass, at launcher release ~25.85t, a bit too much, in any case!).

Cheers,
António Maia
« Last Edit: 09/11/2014 06:55 PM by simcosmos »
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Offline Steven Pietrobon

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Re: A Matter of Height
« Reply #55 on: 09/12/2014 08:21 AM »
Steven, I read your paper and I noticed that you assumed the mass of Orion is 22.2 metric tons. Now, I don't want to force you to throw over your whole architecture, but this recent fact sheet released on the NASA website puts the total mass of Orion at 26.5 metric tons, and the mass without fuel at 17.2. The ∆V of the vehicle is 1340 m/s which implies a 316 s specific impulse (which is inline with the Space Shuttle OMS engine supposed to be used on the vehicle). Link. I've been told that these numbers include a healthy dose of margin but it's nonetheless significantly higher than 22.2 tons, a mass at which Orion would only be capable of 791 m/s.

Thanks for that information. Yes, some numbers have changed with that fact sheet. I will be incorporating them into the system design. Also, the 1338 m/s number comes from Orion going into an elliptical Lunar orbit and then back out again, as required for EM-2 (each requiring 669 m/s). My mission only requires Orion to perform trans Earth injection from a low Lunar orbit, which is 1169 m/s (Apollo 14 worst case). Thus, my Orion does not fly with a full propellant load.

One idea I had for the shortened LAS was to incorporate four liquid LAS engines and propellant tanks into the SM/CM adapter. The nozzles would point through the jettisoned fairing adapters, which have fins attached to provide stability during the abort. If there is no abort, these motors could then be used for propellant settling for the CPS burns.

I think an MLAS type system would be less intrusive to the existing design though. There would be four solid motors in the shroud. I'm worried about stability though, so the SM/CM adapter and jettisoned fairings with fins might still need to be attached during an abort. This means that an additional CM/SM adapter separation plane is still required.

Perhaps the system that has the least impact is to add a hinge to the top of the shroud. During assembly, the motor is hinged down and locked against a bracket on the spacecraft launch adapter (SLA). Once outside the VAB, the LAS is lifted up into place using a crane on top of the VAB, just like during the Saturn IB Skylab flights where the lightning tower was added. The LAS is then locked into place.
« Last Edit: 09/12/2014 08:22 AM by Steven Pietrobon »
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Offline muomega0

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Re: A Matter of Height
« Reply #56 on: 09/12/2014 01:34 PM »
You are likely including this, but LAS mass should be smaller than the fact sheet for an all liquid configuration rather than with solid strap ons.

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Re: A Matter of Height
« Reply #57 on: 09/12/2014 04:17 PM »
Hi Steven,



---------------------------------------------------------------------
I. Quick comment about the VAB's doors vs launcher height issue:
---------------------------------------------------------------------


I was not yet able to properly verify the following but I loosely remember (from personal musings / past brainstorms about the topic and from older NASA documents) that the maximum vehicle height could be somewhere between 390 ft up to 400 ft (~118.9 m up to 121.92 m). In some cases, the vehicle could even go up to ~124m...

Now, one of a few very important details is regarding where is the 'zero' level for the vehicle vs the MLP floor... On current SLS materials it seems that the assumption is to put the exit planes of the boosters / core engines right on top of the MLP's floor...

However, if lowering a little the whole launcher (into the main hole, below MLP's floor, similar to Saturn, etc) then some precious height could be saved...




---------------------------------------------------------------------
II. Failing that, and adding / sometimes repeating what others suggested, there a number of alternatives...
---------------------------------------------------------------------


... But they probably go against how far you wish to go vs the self-imposed constraints of this specific brainstorm.


Some of the things I have been using to maximize the performance of a kind of block2 SLS vs available height are (not necessarily always all at the same time, although those cases are really something incredible to watch and are among my favorites, in a virtual environment free of some other real life constraints):

II.a) Advanced Boosters (solid or liquid, I have been playing with stuff similar to Dark knights and with CH4lox), but this seems a no-go for this case (funny how, with this language, a 5 segment SRB is not looked as an 'advanced booster', hehehe)

II.b)  Upper stage(s) with common bulkhead (you did it)

II.c)  Other choices for US engines (more efficient engines than J-2X, cluster of more than two)

II.d)  Fatter - than core - upper stage (solves some problems but also introduces a few)

II.e)  Drop tank (external diameter equal or greater than the core stage) around a thinner diameter - than core - upper stage... the thinner upper stage could share the diameter of eventual advanced boosters and some numbers massaging could also be done in order to allow:
II.e.1)  the optimization of the drop tank design(s) just for an almost full LEO delivery of the intended mission stack (and for the 'drop tank' to perhaps perform other functions like ascent loads / LEO debris / boil-off protections if required, etc).
II.e.2)  optimization of the inner US for the BEO job(s)

A 'drop-tank-around-thinner-US-with-more efficient-engines' option is probably complicating things too much (?) however, from my own past virtual experiments, I find it very interesting to simulate (it is kind of cheating but the rocket equation likes it  ;D ) also when taking in account extra roles for such 'inner-US' (alternative two stage LV, in-space TUG, etc)

Cheers,
António Maia
« Last Edit: 09/12/2014 04:25 PM by simcosmos »
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Offline JasonAW3

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Re: A Matter of Height
« Reply #58 on: 09/12/2014 06:14 PM »
Wasn't there once some speculation or a plan to add a heavy duty crane to the top of the VAB to assist in final assembly of rockets larger than the Saturn V?

I seem to remember reading about it somewhere, but it may have been some idle speculation.
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Offline Steven Pietrobon

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Re: A Matter of Height
« Reply #59 on: 09/14/2014 07:59 AM »
I was not yet able to properly verify the following but I loosely remember (from personal musings / past brainstorms about the topic and from older NASA documents) that the maximum vehicle height could be somewhere between 390 ft up to 400 ft (~118.9 m up to 121.92 m). In some cases, the vehicle could even go up to ~124m...

Thanks António. Can you explain how you got the 124 m value? That would work with common bulkheads in the US and CPS. The NASA value is 118.87 m, which is the same as your lowest value.
« Last Edit: 09/14/2014 07:59 AM by Steven Pietrobon »
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Re: A Matter of Height
« Reply #60 on: 09/14/2014 08:37 PM »
Hi Steven,

To complete my previous post about VAB vs launcher height constraints:
(after checking a few of my 'development notes')


-----------------------------------------------------------------------------------
I. 119m = Maximum Safe (?) = Current SLS Assumptions (?)
-----------------------------------------------------------------------------------


The current SLS assumption may present a slightly lower height limit (~119m) than other estimations because of several reasons but the most important is due to the design (placement) of the structures that provide the support interface between the vehicle and the MLP.

This was the Launch Mount in AresI case and, in SLS case, the Vehicle Support Posts.

Please see images at:
http://www.nasaspaceflight.com/2012/11/nasa-sls-mobile-launcher-umbilical-plans/

It was not always like that (?) but it seems that current SLS plans are for the HLV to be fully above MLP's surface. The nozzles of the boosters and of  the core's main engines are not much below the MLP's floor level (like was the case with STS SRB posts or with SaturnV F1s nozzles being practically 'hidden' before liftoff).





-----------------------------------------------------------------------------------
II. 122m = Medium Estimation = Non-Raised HLV-MLP Interface
-----------------------------------------------------------------------------------


The 400 ft (~122m) number is something I usually see in many conceptual documents related with SLS and even pre-SLS / transition (after CxP, example: NASA / Advanced Concepts, for '140mt class LEO SLS') and also in several documents about CxP AresV concepts, ESAS (ex: several heavy lifters similar to SLS, LV30, 31 and so on), etc.

This is a “not-to-cross” line for the maximum height of those conceptual vehicles and probably assumes a non-raised design for the Vehicle Support Posts.





-------------------------------------------------------------------------------------------
III. 125M = Absolute Maximum Launcher Height = Not for all HLV Types
-------------------------------------------------------------------------------------------


And then, there are the sets of higher vehicle heights that can be found in other NASA related documents such as in a number of SEI / First Lunar Outpost (FLO): there, it is common to see Comet heavy lifters (the SaturnV derived ones, not the NLS types) to be presented with a total height ranging from 408 ft (~124.4m, cargo version) up to 410 ft (~125m, piloted version).

Such Comet variants would interface with the MLP in a similar way to Saturn (the big F1s nozzles almost fully 'hidden' below the MLP's surface level via a different vehicle-to-MLP interface design than STS / SLS).

The 125m may not be applicable to all launch vehicle designs...




--------------------------------
IV. summary / Final Comments
--------------------------------


Depending of the broader objectives of the paper, what I wrote above may or not result in extra conceptual constraints for this specific brainstorm (vs the reality of the ongoing official SLS conceptual / hardware work).

If needed, I can provide preciser references on a later occasion, for example, I do know that have somewhere in the archives very nice pictures about the height constraints of the VAB. (drawings from FLO documents and cool 3D stuff of more recent years, probably DIRECT, CxP and also from SLS, Mars Mission designs docs, etc)... I also think that have written a post years ago at NSF about this topic.

To conclude, the following is from a page of my 'development workbook' (which I must have taken from several of those sources):

141.00 m : VAB hook height
138.99 m :  VAB door height
   20.06m  : lifted MLP height with Launch Mount
( ~ 6.71m  : Pedestal height )

138.99 – 20.06 gives ~ 118.93 ~119m

http://www.nasaspaceflight.com/2013/02/mobile-launcher-redesign-plan-sls-completion/

This seems to be coherent with the 'safe' value for the maximum allowable SLS height that fits the VAB door.

The 122m may be feasible (with non-raised launch mount / posts and with some adjustments on current umbilicals, etc)...

The 124m /125m really depends... Perhaps not suitable for a vehicle with big solids at the sides (?) because the whole stack would have to be a bit more downward on the MLP's hole...

Cheers,
António Maia

Edits = typos
« Last Edit: 09/14/2014 09:05 PM by simcosmos »
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Offline mike robel

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Re: A Matter of Height
« Reply #61 on: 09/14/2014 11:34 PM »
Probably the largest booster "considered" was the Saturn MLV-24(L).

Data below from Astronautix.com:  http://www.astronautix.com/lvs/satnv24l.htm

The vehicle approached was 180 M (590 feet) tall which considerabley exceeded the theoretical limit of 124 Meters (410 feet). 

American orbital launch vehicle. Boeing study, 1967. 4 260 inch liquid propellant boosters (each with 2 F-1A).; Saturn IC stretched 336 inches with 6.0 million pounds propellant and 5 F-1A engines; S-II stretched 156 inches with 1.2 million pounds propellant and 5 HG-3 engines; S-IVB stretched 198 inches with 350,000 lbs propellant, 1 HG-3 engine. Not studied in detail since vehicle height of 600 feet with payload exceeded study limit of 410 feet.
LEO Payload: 435,300 kg (959,600 lb) to a 185 km orbit at 28.00 degrees. Payload: 185,900 kg (409,800 lb) to a translunar trajectory.

Stage Data - Saturn V-24(L)
•Stage 0. 4 x Saturn MS-LRB-23(L). Gross Mass: 874,100 kg (1,927,000 lb). Empty Mass: 18,100 kg (39,900 lb). Thrust (vac): 15,486.600 kN (3,481,526 lbf). Isp: 304 sec. Burn time: 162 sec. Isp(sl): 265 sec. Diameter: 6.61 m (21.68 ft). Span: 6.61 m (21.68 ft). Length: 47.85 m (156.98 ft). Propellants: Lox/Kerosene. No Engines: 2. Engine: F-1. Status: Study Boeing 1967. Comments: Liquid rocket booster strap-ons using 2 F-1's.
•Stage 1. 1 x Saturn MS-IC-1. Gross Mass: 2,694,703 kg (5,940,803 lb). Empty Mass: 169,719 kg (374,166 lb). Thrust (vac): 45,948.754 kN (10,329,691 lbf). Isp: 310 sec. Burn time: 158 sec. Isp(sl): 270 sec. Diameter: 10.06 m (33.00 ft). Span: 19.00 m (62.00 ft). Length: 48.15 m (157.97 ft). Propellants: Lox/Kerosene. No Engines: 5. Engine: F-1A. Status: Study NASA 1966. Comments: Basic Saturn IC stretched 240 inches with F-1A engines uprated 20% in thrust and 6 second improvement in specific impulse.
•Stage 2. 1 x Saturn MS-II-4(S)B. Gross Mass: 494,100 kg (1,089,300 lb). Empty Mass: 42,300 kg (93,200 lb). Thrust (vac): 5,169.000 kN (1,162,037 lbf). Isp: 421 sec. Burn time: 355 sec. Isp(sl): 200 sec. Diameter: 10.06 m (33.00 ft). Span: 10.06 m (33.00 ft). Length: 24.84 m (81.49 ft). Propellants: Lox/LH2. No Engines: 5. Engine: J-2. Status: Study Boeing 1967. Comments: Standard S-II but with structural strength increased from 86% to 502% depending on station, resulting in 8.6% increase in empty weight.
•Stage 3. 1 x Saturn MS-IVB-1A. Gross Mass: 179,200 kg (395,000 lb). Empty Mass: 20,400 kg (44,900 lb). Thrust (vac): 1,031.600 kN (231,913 lbf). Isp: 421 sec. Burn time: 625 sec. Isp(sl): 200 sec. Diameter: 6.61 m (21.68 ft). Span: 6.61 m (21.68 ft). Length: 22.82 m (74.86 ft). Propellants: Lox/LH2. No Engines: 1. Engine: J-2. Status: Study Boeing 1967. Comments: S-IVB with 16.5 foot stretch, 350,000 pounds propellant, standard J-2 engine.

Status: Study 1967.
Gross mass: 7,386,760 kg (16,285,010 lb).
Payload: 435,300 kg (959,600 lb).
Height: 180.00 m (590.00 ft).
Diameter: 10.06 m (33.00 ft).
Thrust: 94,019.40 kN (21,136,402 lbf).
Apogee: 185 km (114 mi).

Offline Steven Pietrobon

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Re: A Matter of Height
« Reply #62 on: 09/15/2014 08:03 AM »
Thanks António! That's a big help in understanding where the 118.87 m value came from. I think that's a bad decision to use those high launch mounts. Those extra metres would have save me a lot of head ache!
« Last Edit: 09/15/2014 08:10 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

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