Space Transport System using LRB's

Difficult politically but if the STS had been developed as in the OTL but using LRB's, what are the potential changes?

Most obvious is no Challenger type loss but what else could there be?
 
Difficult politically but if the STS had been developed as in the OTL but using LRB's, what are the potential changes?

Most obvious is no Challenger type loss but what else could there be?

Utah doesn't have as much say down the road on what replaces the STS :)
That's actually relevant too because the LRBs would likely be 'recoverable' as well, but would be towed back to Florida or someplace nearby to be 'refurbished' which would reduce the constant 'contribution' (aka jobs/taxes/votes) that NASA was trying to 'spread' around the US with the program. You also have a more clear path to upgrading and modification given the right engine or engine set for the LRBs.

Hey! Maybe we can make the STS an international program earlier and get the Brits involved!

Randy
 
Depends on how the LRBs fit into the architecture.

Stacking the Orbiter on top of an interstage and some sort of LRB would avoid the inherent risks from having the crewed vehicle on the side of the stack, although it would need some imagination to fit the SSMEs in there.

2xF-1 scale engines on each LRB would get somewhere to the thrust, can’t work out how big the booster would be however. The H-1 was dunked in the ocean a few times and it was refurbishable - before the $$ dried up, so no reason to believe why with a bit of investment wouldn’t get the F-1 (probably an F-1A) there too. That said, the Orbiter would still be on the side of the stack - without the adoption of a boat tail style returnable vehicle for the SSMEs on the bottom of the ET - but then you’re developing two reusable vehicles.
 
Stacking the Orbiter on top of an interstage and some sort of LRB would avoid the inherent risks from having the crewed vehicle on the side of the stack, although it would need some imagination to fit the SSMEs in there.
Nah, not too bad.
Squint at a Soyuz, and imagine the shuttle surrounded by three strap on boosters, with massive separockets getting thos near empty LRBs away from the central stage when needed.

Those strap-ons supply fuel to the SSME, but enough fuel left at separation to gimbal hard over for smaller booster engines to aid in the separation
 
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Depends on how the LRBs fit into the architecture.

"Technically" they simply replace the SRB's in most concepts. (Page 3, and Figure 6 and 7) The only way to 'stack' the orbiter was either to remove the engines the stage it was stacked on, (which would have to be based on the ET) or have an LRB "stage" that was big enough to fit both the Orbiter and ET... And THEN comes the hard part of figuring out how to start the engines in-flight :)

Stacking the Orbiter on top of an interstage and some sort of LRB would avoid the inherent risks from having the crewed vehicle on the side of the stack, although it would need some imagination to fit the SSMEs in there.

"Fitting" the engines isn't really a problem but keep in mind you need to feed them with propellant which means you STILL need the ET which works out something like the Saturn-Shuttle concept. If you're willing to do a major, (almost total) rebuild of the Orbiter and turn it into pretty much a straight glider, (see above paper, figure 21) then you can mount the engines to the bottom of re-built ET, maybe podded for recovery. (Same paper, figures 1 through 4) But then you need a monolithic LRB the size of a Saturn V, to develop the new ET, rebuild the Orbiter.... I don't see it happening with any of the budget NASA had.

2xF-1 scale engines on each LRB would get somewhere to the thrust, can’t work out how big the booster would be however. The H-1 was dunked in the ocean a few times and it was refurbishable - before the $$ dried up, so no reason to believe why with a bit of investment wouldn’t get the F-1 (probably an F-1A) there too.

This paper, from 1989, has the F1 rejected due to two F1's per booster not having enough margin for an 'engine-out' situation, (baselining 4 each "new" engines per LRB) and from what little is give it isn't clear if this is the standard F1 or the F1A. Glad to see someone else noting the work done on the H1 recovery/refurbishment experiments :) I'm not so sure the F1 could be so easily since it was a very different beast of an engine. And keep in mind there was work on an F1B a few years ago which planned a "cheaper" F1A (essentially) because the F1 was a pretty expensive engine. Now Rocketdyne in the mid-90s was pitching an 'advanced' version of the RS-27, (who's ancestor was the good-old H1 :) ) called the RS-X, (using RS-27 and Atlas engine parts) which the brochure showed in a 'cluster' configuration that could be two, three, or maybe four engines. But again even the RS-27 had changed so much from the original H1 I'm not sure how the recovery/refurbishment experiments would still apply to an even more advanced engine.

My read from the paper is:
Four (4) of their 'notional' LRB engines with a sea-level thrust of 685,000lbf nets a total single LRB liftoff thrust of 2,740,000lbf leaving and 'engine out' thrust of 2,055,000lbf

Two (late Apollo) F1's at 1,553,200lbf each get a total of 3,106,400lbf which (obviously) drops by half in an engine-out situation.
A single F-1A/B had a takeoff thrust of 1,800,000lbf so two would have 3,600,000lbf and again a less than the 2 million lbf they seem to assume as a requirement for an engine out situation.

Running the number the RS-X only has 424,880lf so four would only amount to 1,699,520lbf so you'd need at least six of them, getting a total of 2,549,280lbf, which would drop to 2,124,400lbf with an engine out. So if you can FIT six engines you still meet the margin :)

That said, the Orbiter would still be on the side of the stack - without the adoption of a boat tail style returnable vehicle for the SSMEs on the bottom of the ET - but then you’re developing two reusable vehicles.

Well there was a studied concept for a "Titan Boost Assist Module" (by the Air Force of course who needed some extra "boost" for their polar orbit missions) which suggested they figured they could strap two sets (four engines total) of Titan II engines and some custom tanks to the base of the ET with "minimum" changes to construction :) But that wasn't 'reusable' in any sense and NASA was pretty adamant about NOT using Titan derived components and especially the toxic propellants it used. In fact that paper mentions that a Titan-esq LRB was considered early on because it was the only propellant combination that allowed an LRB of 'similar' size to the current SRB which was the most aerodynamic and fit the known stress parameters. Later wind-tunnel work suggested that requirement wasn't as 'strict' as they thought :)

Oddly though...
That's one of the articles that I had read in the past.
This article, which I'll cite again, is very interesting because if you compare the more 'official' one you'll note that it doesn't take much "reading-between-the-lines" to see that official paper makes some unsupported assumptions, dismisses some options to easily with no explanation, (methane is rejected as not being 'compact' enough when compared to LH2...???) and 'gently' points out the preferences at which NASA and the study contractors were aimed. While the general recommendation would seem to be the development of a pressure fed kerolox LRB in fact they argue against that but point out that the tankage of the pump-fed kerolox system would not be 'strong' enough to survive recovery. So a recoverable engine/pump pod would need to be developed and since we have to go to so much trouble, well, KSC (and systems operations) would prefer to NOT use another 'fluid' on the pad so here's this idea for a pump-fed hydrolox LRB...

I don't know if Steven Pietrobon, (I'm familiar with him from the NASAspaceflight-dot-com forums) had read this or other LRB papers but I'm guessing so because his paper makes a straightforward case for something that NASA obviously never even considered. His LRB is functionally as similar to the standard SRB as possible, (figure 2, table 3) and actually come in about 44 metric tons lighter with superior performance and enhanced payload to orbit.

He suggests a keroxide version of the RD-170 he calls the RD-17X with a thrust of 1,920,992lbf at sea-level, or two modified RD-180s running on keroxide with the same thrust.
"But don't you need at least 2 million pounds of thrust?"
Yep, that's what the official paper says and the SRBs put out about 2,800,000lbf on lift off so why the difference?
Because when designed for it a pump-fed, throttling engine CAN be run at higher as well as lower thrust levels and if the LRB can be throttled up to 112% your thrust goes up to 2,168,957lbf.
Of course someone will point out that any 'engine out' will cut this in half if you split it between two engines as suggested which is well below the threshold the 'official' paper allows. But lets keep in mind that that assumes loosing and engine you can still get to orbit which you actually can't do with the SRBs nor most of the LRB designs since getting a powerful enough American engine is a problem. LRBs allow you to abort before nominal 'burnout' where as SRBs do not, and most of the LRB abort modes at lower altitude are arguably more survivable. And of course there's the issue with there being no really big keroxide engines to play with hence the need to 'redesign' an existing engine.

Well, there was ONE possible answer, the Beal Aerospace BA-810 developed and tested in the mid-90s. Sure it was designed to be pressure fed and 'only' had a thrust of 809,300lbf, was ablative and expendable but if nothing else the Merlin and RS-62 engines have shown evolution can be pretty straight forward. Pump-feed increases your performance and there are actually some historical work done that shows you can actually make a pretty compact and straightforward turbopump/engine combination, (see the RMI XLR040 "Super-Performance" rocket motor for example) using the specific characteristics of keroxide. (Including using it for cooling) There might be ONE slight problem though:
1610044048259.png


The truck is pretty damn close to the test stand but you get the idea.
A bit more prespective:
1610044284134.png


Not sure you could fit more than one on a 13ft diameter booster :)

Randy
 
I assume the LRB's could be used as the basis of an actual stand alone booster?

Kind of as it was 'assumed' it would be a bit more flexible than the SRB's were and if designed right you could probably 'gang' them together. Granted that a similar pitch was made for things like "SRB-X" among others with the idea you could also use more or less segments to customize the LV. LRB's would be worlds more efficient and likely cheaper :)

Randy
 
Difficult politically but if the STS had been developed as in the OTL but using LRB's, what are the potential changes?

Most obvious is no Challenger type loss but what else could there be?
Unless its going to make launches cheaper and or increase the launch cadence probably not much. Fishing LRBs out of the water to reuse is dubious, that was SpaceX's original plan and they gave it up when it became clear that protecting the delicate components of the booster was just too difficult. And bear in mind the complexities involved in the alternate solution they did make work and that suggests it was really difficult.
 
Unless its going to make launches cheaper and or increase the launch cadence probably not much. Fishing LRBs out of the water to reuse is dubious, that was SpaceX's original plan and they gave it up when it became clear that protecting the delicate components of the booster was just too difficult. And bear in mind the complexities involved in the alternate solution they did make work and that suggests it was really difficult.

LRB's being around the same class as SRBs the extra-cost isn't going to be that much. Besides in NASA's case it was part of the package and they at least wanted the engines back.

In SpaceX's case they actually 'gave-it-up' when they couldn't actually recover a booster. Protecting the 'delicate' bits wasn't that hard but what was needed to actually recover the booster, (you need a ship, divers and a 'safe' sea state, far from impossible, relatively straight forward, but it's not cheap) Propulsive landing was going to happen at some point, (remember the "goal" here is landing on Mars so ideally you want to have the landing part down long before you get there :) ) so they traded the numbers and accepted the payload penalty for it. Once you parse it that way it ends up being finding a a way to stabilize and guide the booster (note at all designed for such an operation mind you) back down while retaining enough propellant to conduct a landing with an engine you can't effectively throttle to assist that landing.

They accepted the risk of the suicide burn but there's a specific reason the Raptor has much deeper throttling capability.

In context a stage actually DESIGNED for recovery and reuse on a regular basis as a criteria won't look like a 'normal' rocket stage because those are difficult to recover without a LOT of active systems and control. A stage designed for recovery will be more squat and tend towards conical, or capsule-shaped so as to require less active and complex control systems and more 'natural' reentry orientation.

On the other hand once you have to take into account things like shipping and transport you get pushed back towards the 'standard' cylindrical stage so...

In the LRB case NASA has to stay within the STS aerodynamic and stress parameters but actually found during some testing that the margins were broader than they'd first assumed. Still given the tendencies of the time it's likely they would have tried for total recovery but settled for 'mostly-intact' tankage and concentrated on saving the engines. Also indicative of the time they will likely forget the previous research they did and insist on something way to complex and expensive to 'save' a few bucks publicly :)

Randy
 
In context a stage actually DESIGNED for recovery and reuse on a regular basis as a criteria won't look like a 'normal' rocket stage because those are difficult to recover without a LOT of active systems and control. A stage designed for recovery will be more squat and tend towards conical, or capsule-shaped so as to require less active and complex control systems and more 'natural' reentry orientation.
You know about this one, but this is for those who aren't the Space Nerds

If only htat had been built in place of the Rockwell Shuttle
 
You know about this one, but this is for those who aren't the Space Nerds

If only htat had been built in place of the Rockwell Shuttle
It's definitely a vehicle I'd love to find an excuse to use sometime. Still needs a stage 1 below or a Stage 2 on top to really make sense, like all single-stage-to-orbit designs.
 
You know about this one, but this is for those who aren't the Space Nerds

If only htat had been built in place of the Rockwell Shuttle

Heh, :) Love HGA's stuff.

It's definitely a vehicle I'd love to find an excuse to use sometime. Still needs a stage 1 below or a Stage 2 on top to really make sense, like all single-stage-to-orbit designs.

Well you folks figured out how to 'vent' the Centaur so if they were to 'imbed' the "upper stage" in that massive central payload bay with the MURP (and abort system) on top...
1610069172809.png


But really it wasn't clear at the time how bad an LH2 booster was so that's why most of them baselined LH2 and why SSTO was seen as a "holy grail" (I can't recall atm which "eminent rocket scientist" it was but he literally stated that once we had 'hydrogen engines' we could do anything :) ) for orbital flight. Truth be told I've been holding out a secret little 'hope' that Starship was actually a "cover" for a SpaceX SSTO vehicle just because but Musk is way to focused on Mars to really concentrate on LEO flight :(

Randy
 
Going to cross-post/port this over here because it actually 'fits' better and besides I like to see my own posts and marvel at how awesome I am...What? :::sigh::: Yes dear I'll get the litter box in just a min... No! Not on the floo.... Yeesh

Ok let me expand a bit on the single "LRB" idea.

The Saturn-Shuttle is a concept that was proposed and eventually rejected during the run-up to the Shuttle:
1610053782528.png


(From HERE)

Essentially an Orbiter and ET mounted on an S1C booster. Right off the bat of course is as designed the S1C is expendable AND expensive. It also had issues that while it didn't require as much 'conversion' of the pad, VAB, and infrastructure as OTL's STS did it wasn't exactly much of a cost or operational savings as Saturn V's were tough to launch. Now you CAN recover the S1C and there were ideas and proposals to do just that but it wasn't really designed for that and it wasn't going to be all that cheap. So what to do?

Well if you insist on it you can always put wings on it and call it a Flyback F1:
1610054767687.png


Or you could just say it was "Right Side Up" I suppose :)

Or you could accept that landing down-range and actually re-designing the S1C to be recovered, refurbished and re-used might make sense. NASA actually thought about that and asked several contractors to study it. Flyback F1 is one of those designs but with the expectation that the penalty, (and it's not huge but it's there) of wing-and-wheels, (along with jet engines and other bits) is acceptable. On the other hand several companies were also studying what were called the "Post-Apollo" Large Launch Vehicles. These were effectively "beyond NOVA" (and really far beyond Saturn) possible super-heavy launch vehicles that NASA would want should they be given the command to 'conquer and subjugate the known universe' while being given a budget to actually carry it out. (Spoiler alert: Didn't happen :) )

These monsters were things like the Sea Dragon, the Boeing HLLV, ROMBUS, Helious and others:
(Check em out here: http://up-ship.com/blog/?p=39970)

Boosters with payloads of a million pounds to orbit or more. One was from a company called Convair and it was called the NEXUS:

General Dynamics Nexus - Wikipedia


en.wikipedia.org
en.wikipedia.org

Now in there report, Convair slipped something in. It was literally a paragraph and some line drawings but it's pretty clear it was both something Convair wasn't really pushing, (building NEXUS would obviously be a 'better' profit margin :) ) nor something that NASA seems to have been asking or looking for (having the budget and support to build NEXUS and all it implied would be the optimum outcome :) ) but it was something "somebody" thought of putting in. Maybe someone had actually listened to what was being said outside NASA and the Contractors :)

But regardless what they came up with was this:
1610055120528.png



To be clear those are both essentially "Saturn V" launch vehicles. The "standard" on the left but note the one on the right those engines don't look right, but yes whereas the "standard" Saturn V has the S1 and SII stages reaching 216ft high the "Saturn V-R" has the both at only 112ft. Now granted it went from 33ft in diameter to 50ft what it did is propose a fully-reusable S1 stage based on the work done on the NEXUS booster. (Arguably the SII is likely reusable as well but Convair only showed this and didn't address it)
What they did was take a Saturn V first stage an redesign the tankage, added a heat-shield and parachutes as so:
1610055470383.png



Now I'll grant you that going from mounting an ET (27ft in diameter) on a 33ft stage to mounting it on a 50ft stage might be a bit of a challenge, (and I'll probably play with some "cut-n-paint" work this weekend, but invite anyone else with better skills, {several billion I'm sure} to give it a go :) ) it's the kind of challenge that engineers are supposed to like so... :)

Randy
 
Maybe slightly outside the topic, but:

We are getting close to the upper limits of what can be achieved with a chemical reaction engine. We really need a quantum leap in technology.

Improvements in efficiency etc are measured in smaller percentages.

There are two new technologies which are knocking on the door:

Hyper-loop: The levitation technology is in use for trains etc (Shanghai airport). It is working. Musk is busy with ramping up speeds for his hyperloop. In essence, the technology is there. How to get into space? As it stands right now, it may require a rather long ramp, preferable running it up a mountain (5 km up will be good). Problem is that the G-force will be 20g, so humans will not be on it first time.
The point is: it is possible to do now.

Space elevator
: Fascinating technology that can work. The science has been done. Now it is into engineering (and money). The space elevator might be the easiest way of getting things from lunar orbit to the surface and from Mars orbit to the surface.

Transport from a space station to a lunar space station or a Mars space station is less of problem.

Trying to get one element (a good rocket) to do all the things is the difficulty. Chopping the problem up in smaller portions might point to the appropriate technology to be used.

OK, slightly off the target, but ...
 
Difficult politically but if the STS had been developed as in the OTL but using LRB's, what are the potential changes?

Most obvious is no Challenger type loss but what else could there be?

The Shuttle very nearly ended up launching on a LRB - that being either the S1C stage or a flyback version of the same stage. A pressure fed booster stage was also looked at for a good long time.

And from the look of things, had NASA insisted that they needed a liquid rocket, either the OMB would have eventually come around to supporting them or Nixon and Caspar Weinburger would have approved it. In OTL, NASA made it harder on themselves by compromising the Shuttle's design every time someone asked them hard questions about whether they really needed this or that. And of course, they missed the real purpose of the OMB's questions, and NASA never re-considered their underlying bad assumptions about how much lift capacity the US needed...

I've always wondered about what the S-I stage (from the Saturn IB rocket) would be like as a booster - the H-1 was a much lower cost engine per Newton of thrust than the F-1 or F-1A was, a relative was in use on the Delta, which was and would continue to be for some time a major workhorse for the US government and in time commercial customers and a more distant relative was in use on the Atlas. Continued development could have made an already fine engine even better. And as pointed out already, the H-1 looked like a good candidate for recovery and reuse.

Anyways, the big deal about a LRB of either kind is that such a booster could be used as the first stage for other rockets. Something like a S-I stage could be launched far more often than a full Shuttle stack, and thus would help drive down operating costs for the whole system. Further, greater demand for H-1 engines (either new or refurbished) would help drive down costs for the Delta.

fasquardon
 
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