Author Topic: Could SLS Mount Falcon Heavy boosters as "Advanced" Boosters"?  (Read 60097 times)

Offline Lobo

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I decided to make a dedicated thread of this hair-brained idea, as it’s probably getting off topic on the Dynetics thread.  And maybe a bit off for the “Engine for Advanced SLS Liquid booster” thread”.

http://forum.nasaspaceflight.com/index.php?topic=30308.150

http://forum.nasaspaceflight.com/index.php?topic=27714.135

My crazy concept, in a nutshell:

Take two FH’s, modify the central core on each to interface with the SLS booster interfaces (on one of the sides that don’t have an outboard F9 on them obviously), strengthen that modified core as needed for the new lateral loads.  And launch.  The FH tri-core booster operates as a single booster.  All three F9’s burn out at the same time and the whole FH is jettisoned.  No crossfeed obviously. 
A strongback could be designed to adapt a stock FH to the SLS core.  That probably a better way to go, so that there doesn’t need to be a custom FH core designed and built.

You now have a booster with more thrust than the Dynetics boster, and should have similar performance overall, that’s basically already designed and flying, and is off-the-shelf, with multiple engine out capability.  There’d be some development costs obviously, but I’d think they’d be just a fraction of designing a completely new booster and new or mostly new engines like the Dynetics/F-1B booster or the Teledyne/AJ-1-E6 booster.  Maybe even less than the ATK advanced Solid boosters.   And the M1D is an all US designed and built engine.  Imagine the economics of scale that come from an extra 54 or 108 of them built per year for SLS?  As well as another 6-12 F9 CCB’s?  In addition to the scale SpaceX will likely already be building them at.  That vs. maybe 4-8 F-1B engines per year and 2-4 booster CCB’s (I’m hoping for at least one SLS launch per year, maybe two down the road once we get an architecture plan).
Plus, this would also give NASA a dedication Orion crew launcher in FH, with full commonality with SLS boosters.  This would be similar to what could have been done with AJAX, except AVH would be a new development.  FH will already be flying.
Plus, according to Steve Pietrobon, looks like the LEO performance of SLS with FH booster would be a whopping 159mt to LEO!  I’ll figure that will come down some figuring the addition of extra mass from a strongback or strengthened FH central core modified to handle the lateral loads of being mounted to the SLS core.  But if you are anywhere over 150mt, or ever 140mt, that’s pretty darn good…especially from a booster that NASA won’t have to pay to have developed.

Any switch to LRB’s will likely need a new Mobile Launcher, so solid ATK boosters will have the advantage of less infrastructure changes.  But I think this would compete very well against other LRB options for SLS. 

I have no idea of SpaceX is even pondering proposing such a thing though.  This is just my hair-brained idea.  :-)
 
(And I’ll stop talking about it on the Dynetics thread.  :-)   )

Offline Chris Bergin

Good man. I was just about to say we need to spliter the SpaceXey stuff, but you already did it. That's exactly what I want members to do (self moderate).

Remember to post a redirect URL to here in the other thread.

Gold star to Lobo! ;D
« Last Edit: 03/25/2013 05:30 pm by Chris Bergin »
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Offline Lobo

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Good man. I was just about to say we need to spliter the SpaceXey stuff, but you already did it. That's exactly what I want members to do (self moderate).

Remember to post a redirect URL to here in the other thread.

Gold star to Lobo! ;D

Yay!

I guess even a blind dog finds a bone every now and again.  ;-)

Yea, before I'd even realized it, I was polluting up the Dynetics thread with this pontification. As that is a -real- Advanced Booster concept, and not just my made up one, I figured I'd better stop doing that.  heheheh.

Offline russianhalo117

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I decided to make a dedicated thread of this hair-brained idea, as it’s probably getting off topic on the Dynetics thread.  And maybe a bit off for the “Engine for Advanced SLS Liquid booster” thread”.

http://forum.nasaspaceflight.com/index.php?topic=30308.150

http://forum.nasaspaceflight.com/index.php?topic=27714.135

My crazy concept, in a nutshell:

Take two FH’s, modify the central core on each to interface with the SLS booster interfaces (on one of the sides that don’t have an outboard F9 on them obviously), strengthen that modified core as needed for the new lateral loads.  And launch.  The FH tri-core booster operates as a single booster.  All three F9’s burn out at the same time and the whole FH is jettisoned.  No crossfeed obviously. 
A strongback could be designed to adapt a stock FH to the SLS core.  That probably a better way to go, so that there doesn’t need to be a custom FH core designed and built.

You now have a booster with more thrust than the Dynetics boster, and should have similar performance overall, that’s basically already designed and flying, and is off-the-shelf, with multiple engine out capability.  There’d be some development costs obviously, but I’d think they’d be just a fraction of designing a completely new booster and new or mostly new engines like the Dynetics/F-1B booster or the Teledyne/AJ-1-E6 booster.  Maybe even less than the ATK advanced Solid boosters.   And the M1D is an all US designed and built engine.  Imagine the economics of scale that come from an extra 54 or 108 of them built per year for SLS?  As well as another 6-12 F9 CCB’s?  In addition to the scale SpaceX will likely already be building them at.  That vs. maybe 4-8 F-1B engines per year and 2-4 booster CCB’s (I’m hoping for at least one SLS launch per year, maybe two down the road once we get an architecture plan).
Plus, this would also give NASA a dedication Orion crew launcher in FH, with full commonality with SLS boosters.  This would be similar to what could have been done with AJAX, except AVH would be a new development.  FH will already be flying.
Plus, according to Steve Pietrobon, looks like the LEO performance of SLS with FH booster would be a whopping 159mt to LEO!  I’ll figure that will come down some figuring the addition of extra mass from a strongback or strengthened FH central core modified to handle the lateral loads of being mounted to the SLS core.  But if you are anywhere over 150mt, or ever 140mt, that’s pretty darn good…especially from a booster that NASA won’t have to pay to have developed.

Any switch to LRB’s will likely need a new Mobile Launcher, so solid ATK boosters will have the advantage of less infrastructure changes.  But I think this would compete very well against other LRB options for SLS. 

I have no idea of SpaceX is even pondering proposing such a thing though.  This is just my hair-brained idea.  :-)
 
(And I’ll stop talking about it on the Dynetics thread.  :-)   )

I will also create one for using the Antares first stage as SLS LRBs.

Offline RocketmanUS

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To many engine problem, so-

So if SpaceX went with a type of Merlin 2.

Used two of the FH booster cores with engine mount for Merlin 2.

That is two FH boosters connected together.
In between the two boosters have the strong back to connect to SLS core.
This way both boosters on a side would separate together.

Problem, is there room for two FH booster cores on each side on the MLP ( opening ) and for the flame trench?

This could then give the other option for a type of FXX commercial HLV.

Problem is SpaceX has shown that they can not deliver on time.
If it is not needed until the 5 seg are used up and that is estimated not to happen for about ten years after 2019, then it could be a possible option.

Offline Zed_Noir

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@Lobo. I think your 150mt IMLEO estimate might be low using the FH boosters on the SLS. My guess is that all FH cores would be the taller strapped-on booster variant. Also the propellant mass fraction would be higher without the cross-feed gear and the upper stage.


Offline russianhalo117

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I created a separate rival thread for this Antares idea.  So I'm not filling up the Dynetics thread with it.  :-)
Thread Link: http://forum.nasaspaceflight.com/index.php?topic=31456.0

Offline go4mars

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Why not crossfeed?  You can still run all 54 Merlin 1D's at full throttle the whole time...  Rather, 36 fall off early with their respective cores, middle cores stay latched on at that point (side-core separation) both with nearly full tanks.

If they get the reusability thing happening, it could potentially be really cheap at some point too. 

Edited for clarity.

p.s.  I like your idea.
« Last Edit: 03/25/2013 06:42 pm by go4mars »
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Offline RocketmanUS

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Why not crossfeed?  You can still run all 54 Merlin 1D's at full throttle the whole time...  Rather, 36 fall off early with their respective cores, middle cores stay latched on at that point, both with nearly full tanks.

Edited for clarity.

p.s.  I like your idea.
If there were three cores on the side of the SLS core how would it look.
Would the Falcon cores be in a straight line or would they be curved to the core. Might not be able to cross feed this way. Either way cross feeding the boosters would add more complication.

Just having two booster attached to each other acting as one unit could reduce complications. Attaching them to SLS from a strong back that would also hold the two booster together might be a better way to go.

I would rather they just look at a commercial FXX ( or similar ) than try and make the Falcon cores work for SLS.
http://forum.nasaspaceflight.com/index.php?topic=27275.0
« Last Edit: 03/25/2013 06:49 pm by RocketmanUS »

Offline Lobo

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To many engine problem, so-

So if SpaceX went with a type of Merlin 2.

Used two of the FH booster cores with engine mount for Merlin 2.

That is two FH boosters connected together.
In between the two boosters have the strong back to connect to SLS core.
This way both boosters on a side would separate together.

Problem, is there room for two FH booster cores on each side on the MLP ( opening ) and for the flame trench?

This could then give the other option for a type of FXX commercial HLV.

Problem is SpaceX has shown that they can not deliver on time.
If it is not needed until the 5 seg are used up and that is estimated not to happen for about ten years after 2019, then it could be a possible option.

Rocket,

Merlin 2 maybe never be built.  If it were to be built, and it were to replace 9XM1D on the F9 and FH lines, then it would just be incorporated into the FH SLS boosters as a matter of course.

I think the assumption that all of those M1D engines is “too many” is a bit of an assumption based on a bit of misplaced fear about the N-1.  I spoke to this on this thread here:

http://forum.nasaspaceflight.com/index.php?topic=30554.345


I’d probably suggest going with building the Block 1B upper stage now, and launching that 8.4m upper stage on a single booster core (maybe with a partial prop load) and making that your common upper stage.  Especially if there’s no sharing with any other LV other than SLS and the SLS LRB.

But, better than any of that I think, is back to my concept of the FH booster.  Mount two FH’s as SLS boosters.  No need to develop a new upper stage other than the Block 1B stage then.  It can launch and test Orion before putting a crew on the SLS stack.

Lobo, the engine count we're talking about with two Falcon Heavies mounted onto the side of the SLS is off the charts.  To my knowledge, the highest engine count for simultaneous firing was 30 on the N-1, and that failed spectacularly.  I've seen Mythbusters struggle with simultaneous ignition with just a few dozen fireworks for goodness sakes.  Now imagine trying to fire up some 54 Merlin 1D engines at the same time alongside the four RS-25 engines on the central core.  That's 58 rocket engines going at the same time.  It sounds like an engineering nightmare.  Ed Kyle and Jim are skeptical enough of the Falcon Heavy's design as it is.  Now imagine their reactions if you were their boss and said this was the way forward. 


Hyperion,

First, as I understand, none of the N-1’s problems were related to it’s first stage engine ignitions.  If any of the engines had failed to ignite, they all would have been shut down on the pad for an abort.  They all lit, but then developed vibration problems at various points after that which caused engines to fail, shut down, etc.  So I don’t think lighting a large number of engines on the pad is much of a potential problem.  I believe much of the N-1’s problems were because the Soviets couldn’t effectively model the vibration conditions with such a large rocket, or test them comprehensively on stands ahead of time.  And also the N-1 had relatively complex plumbing those 30 engines had that was fragile.  They really just lit their rockets in order to see what they did. 
The FH may have a lot of plumbing, but that will be a proven configuration by the time it would even be considered.

And beyond that, you are looking at this wrong.  You are looking at each engine as it’s own separate rocket.  Like you are building a new monolithic rocket with 58 engines on the first stage.  But instead what you are building is a monolithic core with four engines, and two boosters, each with effectively –one- engine.  As all three cores and all the engines act together as a single booster on a side.  Each engine is no more than a part of that booster just as any other part of that booster is just a part.  A structural element, a panel, a piece of plumbing, etc.  (important pieces, no doublt) 
NASA buys the FH booster because the FH booster has flown X number of times with no major problems and no LOM in 2023 (or whatever time they look at advanced booster).  If the FH has been riddled with problems over many years year, then it wouldn’t be a viable option to even consider.  So this assumes only that if flies, and flies reliable for several years.
You don’t look at the individual engines, or even the individual cores as separate entities.  If an engine doesn’t light on the pad, then the whole stack can be shut down.  If a single engine shuts down in flight, then an engine on the opposite booster is also shut down.  The stack will probably have enough margin that a few engine pairs can go out and still have nominal ascent.   

You look at the tri-core FH booster as a single booster.  It’s reliable, or it’s not.  It can withstand an engine out event, or it can’t.

This is probably better discussed further over here though:

http://forum.nasaspaceflight.com/index.php?topic=31455.0


So I think the point of “too many engines” would have to be proved, rather than just assumed.  Unless FH starts having some problems with 27 engines in their configuration, and they develop an LV that proves itself reliable, then SLS is just using two proven reliable boosters.  The number of individual engines is sort of immaterial.

 To address your other questions, the FH –should- fit across the pad.  Three F9 cores is about 11m across.  A little more with spacing.  The S-1C had a 10m core, but was over that with the diameters of the F-1 nozzles.  This link says the trench is 18m wide, but I don’t know if that full width can be used.

http://science.ksc.nasa.gov/facilities/lc39a.html

I don’t know the dimensions of width between the far ends of the STS SRB nozzles, to the opposite side of the top SSME on the Orbiter, but those seem to be a good distance apart.  And they fit within the width of the flame trench.  (if someone knows, I’d like to know what the dimension is).

As far as a booster with just two F9 boosters, as Steve Pietrobon said, that could work too.  What you’d probably have there, like you said, is the strongback between them.  The strongback would be fitted with with standard FH booster mounts, and the two F9 CCB’s would mount to either side of it just as they would to the central FH core.  The strongback would be designed to space the two F9 CCB’s an appropriate distance away from the SLS core.  That could certainly be an option if the full FH was deemed too powerful or some other problem.  But the full FH –is- already a booster being designed and will be in production at that point.   It’s not like you are saving anything by going with a two core booster than a three.  If SLS can mount the Dynetics booster at 3.6Mlbs each, then it –should- be able to mount the two FH’s at 3.8M lbs each.  But if not, they could look at a two-booster with central strongback design.

As far as SpaceX making deliveries, this is way in the future.  SpaceX will have a good track record of delivery and reliability by the time NASA would likely be considering an advanced booster, or they won’t.  If they don’t, this won’t even be considered. 

However, keep in mind, the difference between looking to use FH for SLS advanced boosters vs. ATK advanced boosters, Dynetics boosters, or Aerojet/Teledyne boosters, is the FH would have been flying for several years, and have a real-world track record.  As where the other three won’t.  And there’s something to be said for a proven design.  On paper, having that many engines might seem to be a liability vs. something like the Dynetics proposal.  But in the real world, if that many engines is flying and been reliable, then it by default becomes more reliable than an booster with fewer engines that has never flown.  And it would already be it’s own stand alone LV, where the other’s would not. 

This concept isn’t without some issuse to be worked through.  I’m not trying to say that.  But there’s just lots of upside if indeed SpaceX has a valid design, and FH is a reliable booster.  Existing design, shared costs, American built and designed engines, economics of scale, etc.
Just seems that all of this talk about a brand new liquid booster design, with maybe putting a new upper stage on it so it can fly on it’s own and compete in an already over-crowded EELV-class market?   There’s not enough business for the EELV [heavy] class LV already.  Much less adding a new player to that. 
However, there is already an EELV-heavy booster under development, that’s composed of modular smaller CCB’s.  Why not look at that?  And see if the perception of a problem with that many engines is real…or a misconception?

Offline Lobo

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Why not crossfeed?  You can still run all 54 Merlin 1D's at full throttle the whole time...  Rather, 36 fall off early with their respective cores, middle cores stay latched on at that point (side-core separation) both with nearly full tanks.

If they get the reusability thing happening, it could potentially be really cheap at some point too. 

Edited for clarity.

p.s.  I like your idea.

I’ve thought of that, my three hang ups on it are:

a)   You have a high-energy sustain core already.   The boosters just need to get it going, they don’t need to do too much of the ascent.  No kerolox engine will get close to those RS-25’s.  The quicker you can kick loose that extra mass the better I’d think.  All you need to do is get the core high enough and fast enough where the RS-25’s can take over without too many gravity losses.  And I think the normal burnout altitude and speed of a non crossfed FH would be more than amble for that.  I don’t know if that central FH core is much more than a liability if you hand on to it for too long.  Someone with more knowledge than me could answer that.
b)   The bigger problem is separation.  I’d have the whole FH assembly fall out and away like the SRB’s.  However, if the two outboard F9’s on each side jettison, they actually jettison parallel to the attachment point, rather than out and away from it.  Maybe this would be ok, but I wouldn’t want one hitting the SLS core when jettisoned. 
c)   You introduce and extra staging event, with four extra separations for a total of 6.  NASA seems to want to stay away from any more than –two- separations, and referred to that as to their reasoning for not considering Atlas V Phase 3a in ESAS, that would have four booster.  They considered 8.4m hydrolox SLS type cores with two Atlas V’s, or two Delta IV’s, but none with more than just two boosters, like AJAX.  I assume this was for the same reason.  In my concept, each FH is treated like a single dumb booster.  No crossfeed, and no extra separation events.  Just two, just like the SRB’s…

Offline Lobo

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If there were three cores on the side of the SLS core how would it look.
Would the Falcon cores be in a straight line or would they be curved to the core. Might not be able to cross feed this way. Either way cross feeding the boosters would add more complication.

Just having two booster attached to each other acting as one unit could reduce complications. Attaching them to SLS from a strong back that would also hold the two booster together might be a better way to go.

I would rather they just look at a commercial FXX ( or similar ) than try and make the Falcon cores work for SLS.
http://forum.nasaspaceflight.com/index.php?topic=27275.0

The FH would be a –standard- FH.  It would just need a strongback adaptor, or a modified central FH core to be strengthened to handle the lateral loads of being side mounted to the SLS core. 
It would look like a bit of an “H” cross section.  The outboard FH booster might need some cross bracing and shock absorbers to keep them from moving around too much.  The FH will have a different vibration profile when used as an SLS booster rather than by itself, obviously, and that will need to be looked at. 

FXX is brand new core, and I think SpaceX would need completely new tooling to make cores that big.  And that booster would directly compete with SLS.  Until such a time when NASA is considering ditching SLS, FXX really has no customer.  Certainly no commercial customers are out there any time for a long time for it.  FH will be a production booster, and will already exist.

Offline RocketmanUS

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If there were three cores on the side of the SLS core how would it look.
Would the Falcon cores be in a straight line or would they be curved to the core. Might not be able to cross feed this way. Either way cross feeding the boosters would add more complication.

Just having two booster attached to each other acting as one unit could reduce complications. Attaching them to SLS from a strong back that would also hold the two booster together might be a better way to go.

I would rather they just look at a commercial FXX ( or similar ) than try and make the Falcon cores work for SLS.
http://forum.nasaspaceflight.com/index.php?topic=27275.0

The FH would be a –standard- FH.  It would just need a strongback adaptor, or a modified central FH core to be strengthened to handle the lateral loads of being side mounted to the SLS core. 
It would look like a bit of an “H” cross section.  The outboard FH booster might need some cross bracing and shock absorbers to keep them from moving around too much.  The FH will have a different vibration profile when used as an SLS booster rather than by itself, obviously, and that will need to be looked at. 

FXX is brand new core, and I think SpaceX would need completely new tooling to make cores that big.  And that booster would directly compete with SLS.  Until such a time when NASA is considering ditching SLS, FXX really has no customer.  Certainly no commercial customers are out there any time for a long time for it.  FH will be a production booster, and will already exist.

I don't think that will work. More than likely it would fall apart.

Would be better just to attach each booster to the core and have them separate at the same time as one unit.

Offline baldusi

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Lobo, let me rephrase about the AJAX concept adapted to the Falcon Heavy boosters. The concept was to make an adapter truss structure that would both take the weight of the stack at the pad and transfer the thrust to the interstage. Of course you could design it for two or three boosters per side. But you'd separate the truss from the core at booster's MECO. Thus, you'd have just one separation even (or two, one for each truss, but still the same than SRB).
If you went with two you could put a single truss and attach a booster to each side. If you went with three boosters per side, you could use dual trusses and "wrap" the boosters to the core. I would think that you'd use three stock boosters per side (no F9 v1.1 core).
If you wanted extra performance, and were willing to accept the extra risk, you could always add the cross feeding plumbing to the central booster on the three booster configuration. It would require some "custom" plumbing, but should be able to use basically the same tooling (and valves and such).
Let's remind the total thrust of the boosters:
1 booster =   6.8MN
2 booster = 13.6MN
3 booster = 20.4MN
It might get to be "too much", in fact.

Offline go4mars

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Regarding cross-feed
a) The quicker you can kick loose that extra mass the better I’d think. 

b)  separation...  if the two outboard F9’s on each side jettison, they actually jettison parallel to the attachment point, rather than out and away from it.  Maybe this would be ok, but I wouldn’t want one hitting the SLS core when jettisoned. 
c)   You introduce and extra staging event,
a) Cross-feeding would kick loose 2/3rds of the dry booster mass far sooner.  I'm curious, did Steve run the numbers on a cross-fed version, just for fun? 

b&c) Are basically the same point.  First, there will be plenty of experience, measurements, and statistics related to side-core staging which can be evaluated, with mitigations figured out (if required) long before SLS flies.   
Also, I suspect the side-core staging event would likely be low enough that the atmosphere would help drag/usher side-cores on the booster in a safe orientation (just a hunch). 
« Last Edit: 03/25/2013 08:54 pm by go4mars »
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Offline spectre9

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You would need too much mass for the FH outboard boosters to stiffen it.

You can't just keep adding metal on metal on metal. That's not how rocketry works you eat into the payload too much.

The idea is to have an aerodynamically stable shape so the loads are distributed well enough that you don't have to over engineer the stiffening.

Sorry to go throwing cold water on this but I find it absurd.

Offline spectre9

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Offline deltaV

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Maybe you could use Falcon Heavies as SLS boosters if you tried hard enough but why would you want to?

A new booster using six of SpaceX's 650 klbf methane engines would have 3.9 Mlbf thrust. That's a bit more thrust than Dynetics's already over-performing proposal (see http://www.nasaspaceflight.com/2012/11/dynetics-pwr-liquidize-sls-booster-competition-f-1-power/). The ISP should be substantially better due to staged combustion and methane. The dry mass would be somewhat worse though. Hopefully the net result is enough over-performance to allow for single engine-out from launch.

Such a booster could be designed to be usable standalone as well. (It's presumably a lot easier to design the cores for multiple uses from the get-go than redesigning later.) Arranging 1 or 3 of these cores analogously to EELV/Falcon would give on the order of twice the LEO performance of Falcon v1.1 and Falcon Heavy respectively. That may not be as big as Elon (or Congress) wants but it's pretty good. A single one of those 650 klbf engines would make a nice upper stage for the 3-core version but would be too big for the single-stick version. The single-stick version could perhaps use the existing single-Merlin upper stage.

Why would Elon scare NASA away with 54 booster engines when he has a chance to get NASA to pay part of the development cost of the super-heavy launch vehicle he wants?

Offline Lobo

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You would need too much mass for the FH outboard boosters to stiffen it.

You can't just keep adding metal on metal on metal. That's not how rocketry works you eat into the payload too much.

The idea is to have an aerodynamically stable shape so the loads are distributed well enough that you don't have to over engineer the stiffening.

Sorry to go throwing cold water on this but I find it absurd.

That’s ok, I find your finding this absurd…well…absurd.

You have some calculations and modeling to back all of this up I’m sure.  Please post it all in gory detail, as I’m sure we’ll all love to see it.

I know you think you are the final authority in all things, but how could you possibly know for –sure- that the outboard boosters would need too much mass to stiffen?  Really?  How could you possibly –know- that??  You can speculate that it –might- need too much, it perhaps it would.  But you are claiming to know something that I’m not sure how you could know.

First of all, if Steve Pietrobon’s number of 159mt to is even anywhere in the ballpark of accurate, that means you have almost 30mt of margin over the NAA2010 mandate of 130mt to LEO.  And it’s probably actually even more than that since you’d been jettisoning all of that extra mass at booster sep, not carrying it to orbit.  So I don’t know what that would be, but it seems like a fair amount of mass margin for stiffening the boosters, does it not?  But then again, I’m not claiming I know it would work, as you are claiming to know it wouldn’t.  I’m just postulating the idea, and that it might be worth a look to examine by those at NASA or SpaceX would be able to find out if there’s any major show stoppers or at least enough problems to make it unfeasible.

But to wave your hand and dismiss this as “absurd” seems both premature, and arrogant.

Secondly, exactly how much do you need to stiffen the outboard F9 cores?  They will already be build stiff enough by SpaceX that they will fly on FH without moving around too much.  On an FH booster, they will interface with the central F9 core in exactly the same way.  So, how would they suddenly need all of that metal to stiffen it?  Now, there might be vibration being generated or reflected back by the SLS core that would give the outboard F9 cores stresses in excess of what they’ll see on FH.  That’s possible.  Or the aerodynamic forces coming off the SLS core and/or PLF that are different enough from those coming off the FH PLF that would cause then to exceed FH’s aerodynamic forces.  Either of those are possible, and would need to be evaluated.  Are there other criteria in play that I’m missing besides those two? (certainly possible).

But without looking at those, how can you possibly make the claim that so much metal cross bracing that you can say the concept is absurd?
Maybe that bracing would be minimal, and just need to account for a few conditions that the FH booster doesn’t see by itself?  That’s entirely as likely as it being too heavy.

Besides….I did preface this thread by claiming it was my “hair-brained” idea  ;-)

And, I think you are approaching it wrong.  Instead of looking at it and trying to pick it apart for why you don’t –think- it will work.  Picture you are the head of an engineering team at NASA.  Your boss comes in and says, “We are too over budget with SLS and our HSF capitol program to afford brand new 1-off, purpose build booster to replace eht 5-segs after the existing stock of casings run out.  It will cost too much to restart the production of the 5-seg steel casing.  But…we need to do something.  We want to use an existing booster that will be cheap and available so we don’t have to pay for it’s full development.  The Falcon Heavy is flying and has been for 10 years (hypothetically).  New advanced boosters will cost X dollars.  We have half of that available.  Here’s the SLS core, and here’s the FH booster.  Make it work for ½ of X dollars”

You can simply say it can’t be done, and go to lunch and play Angry Birds on your smart phone.  Sounds like that’s what you’d do…but I’m more curious about “what if”…

Or on the other foot, let’s say you are the head of an engineering team at SpaceX.  Your boss comes in and says, “NASA wants to know if we can provide a Falcon Heavy based booster for SLS that’s faster and cheaper than any of their other 5-seg replacement options.  IF we can, there’s a good chance we can get into bed with NASA and SLS.  We –want- to get into bed with them.  “It can’t be done is not an option”.  Tell me how it CAN be done, and if there’s any way it happens for significantly less than the other booster replacement options.  Make it happen…”

As Jim has said many times, with enough money, you can do anything.  So I’m sure this could be made to work with enough money.  But it’s potential appeal is if it could be done significantly cheaper than other options.  If it’s the same price to develop and produce as ATK advanced solid, or the Dynetics booster, than it’s of no real advantage is it?
But, a Dynetics/F-1B, or ATK Advanced solid class booster will soon exist for commercial payloads.  It’s there.  It will exist.  NASA won’t have to develop it or pay for it’s overhead.  Don’t you think there’s some merit looking at that to see if there’s any affordable way to use it on SLS?

Offline Lobo

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I don't think that will work. More than likely it would fall apart.

Would be better just to attach each booster to the core and have them separate at the same time as one unit.

As I was telling Spectre, not thinking it will work is not the same as not -knowing- it would work.  But your opinion is duely noted.  And you might be right.
The good thing is that if there was some sort of major show stopping problem, it would be discovered LONG before they got too far with it in the evaluation review process.  :-)

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