STUDY SUMMARY- Near Term Intermediate Launch Vehicles- Low Cost S-IVB Stages

Here's an interesting Bellcomm study from 1969 on the possibility of producing a low-cost S-IVB stage for use on an "Intermediate Launch Vehicle" to be used for launching Air Force and NASA payloads in the 1970's.

The Air Force, in usual form, was proposing their own vehicle, using new 156 inch solid rocket boosters and an all-new 15 foot diameter Titan-based core vehicle, using a storable propellant first stage, and an all-new 15 foot diameter LH2 powered second stage using a J-2 engine... only 15% smaller than the S-IVB itself, but a completely new from scratch stage... (about as stupid as it gets-- dump something you already have that works great and is completely manrated, for something that's an all new development project from square one.) Alternatively, the Air Force proposed developing a new solid rocket motor cluster first stage comprised of FOUR of the new 156 inch SRM's strapped together to make a first stage, with the new LH2 upper stage atop it.

NASA plans included the 260 inch large monolithic SRM being developed by Aerojet General (which was test fired upside down in a silo constructed in southern Florida in a subscale test) and also several iterations of the "Interim Launch Vehicle" (ILV) proposals using Saturn derivative vehicles like INT-20, which would have paired a Saturn V S-IC stage first stage with fewer F-1 engines (depending on the version) and an S-IVB second stage, among others.

The study centers on the fact that the S-IVB second stage, which was designed and built with dry mass being the critical design criteria, along with restart capability, for the lunar mission, was coming in at about TWICE the cost of any of the other proposed first stages under consideration, INCLUDING S-IC. McDonnell Douglas, the contractor in charge of S-IVB development and construction, had made a series of proposals to enable a lower-cost S-IVB, including more automated and simplified production, and not test-firing the individual stages before flight. Using various approaches to cutting costs, it was felt that using the existing Saturn-derived technologies to build simplified and cheaper versions of the S-IVB could result in an ILV rocket with a cost of about $200 per pound to 100 nautical mile low Earth orbit (LEO). This was roughly commensurate with the best overly-optimistic (as cited in the report) cost projections from the Air Force for their new proposed launcher, using already existing and manrated stages and equipment.

It's a fascinating look into what "might have been". Unfortunately, the powers that be chose to dump virtually all the existing Saturn development work and infrastructure and start from scratch with the Space Shuttle, and ended up in bed with the Air Force to win approval and badly needed funding for the shuttle program, and hopelessly compromised the design to meet Air Force "requirements" that never materialized anyway, resulting in a fundamentally flawed vehicle incapable of meeting the original goals planned for it.

Enjoy! OL JR

View attachment Low Cost SIVB Study Summary.txt

they already had the perfect LEO launch vehicle...the Saturn 1b!!!

luke strawwalker said:

Here's an interesting Bellcomm study from 1969 on the possibility of producing a low-cost S-IVB stage for use on an "Intermediate Launch Vehicle" to be used for launching Air Force and NASA payloads in the 1970's.

The Air Force, in usual form, was proposing their own vehicle, using new 156 inch solid rocket boosters and an all-new 15 foot diameter Titan-based core vehicle, using a storable propellant first stage, and an all-new 15 foot diameter LH2 powered second stage using a J-2 engine... only 15% smaller than the S-IVB itself, but a completely new from scratch stage... (about as stupid as it gets-- dump something you already have that works great and is completely manrated, for something that's an all new development project from square one.) Alternatively, the Air Force proposed developing a new solid rocket motor cluster first stage comprised of FOUR of the new 156 inch SRM's strapped together to make a first stage, with the new LH2 upper stage atop it.

NASA plans included the 260 inch large monolithic SRM being developed by Aerojet General (which was test fired upside down in a silo constructed in southern Florida in a subscale test) and also several iterations of the "Interim Launch Vehicle" (ILV) proposals using Saturn derivative vehicles like INT-20, which would have paired a Saturn V S-IC stage first stage with fewer F-1 engines (depending on the version) and an S-IVB second stage, among others.

The study centers on the fact that the S-IVB second stage, which was designed and built with dry mass being the critical design criteria, along with restart capability, for the lunar mission, was coming in at about TWICE the cost of any of the other proposed first stages under consideration, INCLUDING S-IC. McDonnell Douglas, the contractor in charge of S-IVB development and construction, had made a series of proposals to enable a lower-cost S-IVB, including more automated and simplified production, and not test-firing the individual stages before flight. Using various approaches to cutting costs, it was felt that using the existing Saturn-derived technologies to build simplified and cheaper versions of the S-IVB could result in an ILV rocket with a cost of about $200 per pound to 100 nautical mile low Earth orbit (LEO). This was roughly commensurate with the best overly-optimistic (as cited in the report) cost projections from the Air Force for their new proposed launcher, using already existing and manrated stages and equipment.

It's a fascinating look into what "might have been". Unfortunately, the powers that be chose to dump virtually all the existing Saturn development work and infrastructure and start from scratch with the Space Shuttle, and ended up in bed with the Air Force to win approval and badly needed funding for the shuttle program, and hopelessly compromised the design to meet Air Force "requirements" that never materialized anyway, resulting in a fundamentally flawed vehicle incapable of meeting the original goals planned for it.

Enjoy! OL JR

View attachment 178338

Click to expand...

First, Table 1, USAF vehicle data...


Second, Table 2- Saturn derivative launch vehicles...


Third, estimated low-cost guidance system for S-IVB based vehicles-- a study done by MSFC and MDA to replace the separate Instrument Unit (IU) ring containing the guidance system for the Saturn V and Saturn IB atop the S-IVB stage, with a simpler "plug-n-play" type system installed on the stage itself as a "kit" or "module" rather than as a separate vehicle element, therefore saving considerable money. MDA was confident that a system could be developed or adapted to the purpose that would reduce the cost to approximately $1 million per flight...


Appendix 1, Standard Launch Vehicle Cost study...


Tables 1 and 2, displaying various unit costs for vehicles based on varying assumptions of various flight rates or buy rates (in the case of constructing a set number of stages or components and storing them for later use, as was done with Saturn V and Saturn IB, versus "build them as you fly them"...)


Low Cost SLV ground rules (guiding the study)...


Continuation of the previous ground rules...


Appendix B- Discussions with MDA and others on low cost S-IVB...


Next page of Appendix B...


Finally, last page of Appendix B...


Later! OL JR

NJRick said:

they already had the perfect LEO launch vehicle...the Saturn 1b!!!

Click to expand...

True to an extent, BUT, the first stage (S-IB) was the limiting factor to the performance growth of that vehicle.

There was a proposal for a 20 foot stage stretch and possibly increasing the H-1 engine count to 9 or even 10... but it would require a BIG redesign of the propellant manifolds feeding the engines under the stage as well as the thrust structure holding them all. H-1 upgrades were also possible, but not enough to get the kind of performance that they wanted and needed to make the Saturn IB capable of the performance levels they were talking about.

Adding a pair of solids to the S-IB was an interesting proposal, but opens a whole 'nuther can of worms... redesign of the stage to attach and transfer the thrust of the solids to the vehicle, in-flight separation of the solids from the core stage, redesign for airstarting some of the H-1 engines, redesign and modification of the ground support equipment (essentially requiring basically "shuttle mods" to one of the MLP/LUTs at KSC to support such a vehicle, which meant that you couldn't launch the vehicle from the existing Saturn I pads at LC-34 and LC-37 at CCAFS, meaning ALL launches would have to be conducted from KSC, which the Air Force wanted no part of... (and in fairness was a rather expensive way to do it, especially for unmanned launches). The Air Force wanted a WTR capability (polar launches out of Vandenberg) which would have required all-new pad(s) out there as well if Saturn IB or a solid-boosted Saturn IB was to be the "single launcher" for most of the Air Force and NASA launches. Interestingly, the Air Force figured that they could support a solid-boosted system using either a cluster of 156 inch SRM's or an all new 15 foot diameter "super Titan" (basically, the "Barbarian" proposal) flanked by a pair of 156 inch SRM's, possibly even the NASA-developed 260 inch monolithic Aerojet SRM first stage... Cost projections showed that the differences between the proposals, in terms of operations costs, weren't really that big. The main costs would be in development-- adapting something you are already flying is cheaper than developing something completely new from scratch.

There were proposals for replacing the H-1 engines with F-1, although basically it would require a combination of F-1 and maybe the four outer H-1's to really make sense, at least with the stock F-1. In addition, the F-1's dry weight was heavier than the cluster of H-1's-- and replacing the inner four H-1's with a single F-1 would have been MUCH heavier than the cluster of H-1's. It would also require redesign of the propellant manifolds and thrust structure of the S-IB to feed an F-1 instead of four H-1's in the center. Using TWO F-1's would be a viable alternative and allow for using a single engine type (and allow the H-1 to be retired, reducing the number of "procurement programs" necessary to keep a vehicle operational) but again, would require a BIG redesign of the S-IB to accomplish-- a complete revision of the propellant ducting feeding the engines and of the thrust structure. Plus, a pair of F-1's would rapidly over-accelerate the stage as propellant burned off, and since F-1 wasn't throttleable, the only alternative I can see would be for the guidance and control system to be programmed to monitor the engines and shut one down after a minute or so of flight, well before the 2 minute mark in flight, to reduce the thrust to just the remaining firing F-1 engine. If I were designing for that, I'd have the GNC system monitoring the engines from startup to the shutdown point, and recording "points" against each engine for any off-nominal conditions that could mean trouble later on, and then when the shutdown point was reached in flight, the guidance system would then shut down the engine that had more "points" against it in startup and operation to that point. Of course the GNC system would also have to switch over to a new off-center thrust condition of the single remaining firing F-1 engine that would normally continue to burn until stage shutdown just prior to staging, but that's not particularly difficult. The other issue is, with only a single remaining F-1 firing for the second half of the first stage flight, you have no roll control with the single engine. You'd either have to have a roll-control thruster system to take over roll control at that point, , or some small vernier engines burning to provide roll control authority. Maybe the S-IVB APS thrusters could serve that function-- I don't know. But it would have to be figured out. Basically if you have to redesign the stage for all that, you'd probably not have much more work to do to redesign for unitary propellant tanks, IOW, a S-IB sized version of the S-IC's single LOX and Kerosene tanks, and an intertank between them, and ditch the cluster tank arrangement altogether. One could save weight that way, though it doesn't gain you much advantage on a first stage, and of course the redesign would be expensive. Basically there's no justification for it. Either your modifications can make use of the existing S-IB stage, or you just switch to the S-IC stage. From this study, the S-IC stage didn't seem like too expensive of an option, and it was already developed... when you figure design, development, testing, and certification costs to get it to the point that the S-IC already was at, versus perhaps slightly cheaper manufacturing and perhaps operational costs, it would take a LONG time, if ever, to make back any "savings" from a smaller unitary tank new S-IB replacement stage. For a minimal investment, you'd have MUCH better returns on a similar "simplification" program for the S-IC stage to make it cheaper to manufacture, and that way you still maintain an HLV capability at some point in the future when/if you need the capability...

Now, this does neglect one thing... the F-1A... From the studies I've read, the plan was to replace the F-1 on the second run of Saturn V's, had there been a second production run of Saturn V's... (which of course sadly there weren't). The F-1A would have increased the thrust from the 1.5 million pounds of the F-1 to 1.8 million pounds per engine... and with a turbine redesign on the turbopump, the engine could have produced over 2 million pounds of thrust. Even the 1.8 million pound thrust improvement would have allowed a substantial upgrade in capabilities to the Saturn IB stage without requiring H-1 engines at all, replacing eight 205,000 lbs thrust cluster of H-1's (total thrust of 1.64 million pounds), but it still would have required the redesign of the propellant manifolds under the stage and the thrust structure. Whether this was worth the money or not I don't know. I have a feeling that basically, other than a tank stretch to the existing Saturn IB first stage, substantial redesign simply wouldn't be worth the trouble or expense. But the F-1A seems to be the likeliest and most straightforward improvement to the S-IB.

Barring that, it seems to me that the "best" way forward would have been to pursue the development of INT-20. That would be pretty straightforward; it's basically 'de-rating' the existing Saturn S-IC stage for fewer engines and lighter loads. Since it was already developed and certified for larger loads, it would basically be a turn-key deal, more or less. It also opens the door for modest investments, like perhaps going ahead with the S-ID development of a "stage and a half" concept, which would buy even MORE performance from the INT-20 concept, and allow for a "1.5 stage to orbit" vehicle using NO upper stage, which would have been a REAL money saver for payloads in the 20-25 ton (shuttle) range, all on kerosene engines.

It's really sad to see that the goal they were pursuing, cheaper launch to space, was within their grasp, based on already developed or near-term development of existing systems and perhaps some new expendable components. Instead, politics became involved, and NASA being an engineering agency rather than an operations one, wanted the "challenge" of designing a new system, and cooked the books to get it, making all kinds of wild assumptions of cost savings to justify it. In the end, NASA got their totally new shuttle, but it turned out to more expensive than the Saturn systems they junked before they even attempted to optimize them and reduce costs. The Air Force jumped on board and then discovered the folly of the "single manned reusable launch vehicle for all payloads" approach with the Challenger disaster of January 1986. The Air Force got their big Western Test Range (WTR) pad at Vandenberg, but it was for shuttle, and never launched a single vehicle. It was eventually redesigned and modified for EELV (Delta IV heavy). Shuttle never achieved the ridiculously high flight rates required to approach anything like cost effectiveness-- in fact, it would have been just about as cheap to keep launching Saturn V's, which were WAY more powerful and much safer than the shuttle turned out to be.

All water under the bridge now... but only now are we figuring out exactly what we lost... As shuttle manager John Shannon told the Augustine Commission, "reusability is a myth" (at least the shuttle form of it) and basically expendable vehicles, not requiring refurbishment after launch (at least not extensive manpower intensive expensive refurbishment like shuttle required) is actually cheaper (which is part of the reason why the shuttle SRB casings to be used on SLS, assuming it ever flies, will be expended and dumped on the bottom of the ocean after flight rather than recovered for reuse). It remains to be seen if the SpaceX method of reusability (boost-back to vertical hover, descent, and landing) will work as advertised and be cheaper than a fully expendable booster designed for lowest cost manufacture, assembly, testing, and operations. Basically all shuttle taught us was how NOT to design a reusable vehicle, and ESPECIALLY how to not design a low-recurring cost launch vehicle...

Later! OL JR

Luke,
I hear ya on the 1b and growth potential.....but you have to admit it looks cool!
seriously, I have always wondered if there was any way to squeeze more performance out of the H-1s....not sure if there was any growth left in the H-1 design. I know lifting a an Apollo CSM pretty much maxed the 1b out...but it was a reliable booster and they had the infra structure in place for it....and as you indicated earlier...it was already man-rated and a proven booster.

I think you are spot on in your point that we are only now finding out what we lost. I know it was a different time...but looking back we had two incredible boosters in place in the Saturn V and the 1b...and we just left them at the curb and walked away. just amazing.




QUOTE=luke strawwalker;734835]True to an extent, BUT, the first stage (S-IB) was the limiting factor to the performance growth of that vehicle.

There was a proposal for a 20 foot stage stretch and possibly increasing the H-1 engine count to 9 or even 10... but it would require a BIG redesign of the propellant manifolds feeding the engines under the stage as well as the thrust structure holding them all. H-1 upgrades were also possible, but not enough to get the kind of performance that they wanted and needed to make the Saturn IB capable of the performance levels they were talking about.

Adding a pair of solids to the S-IB was an interesting proposal, but opens a whole 'nuther can of worms... redesign of the stage to attach and transfer the thrust of the solids to the vehicle, in-flight separation of the solids from the core stage, redesign for airstarting some of the H-1 engines, redesign and modification of the ground support equipment (essentially requiring basically "shuttle mods" to one of the MLP/LUTs at KSC to support such a vehicle, which meant that you couldn't launch the vehicle from the existing Saturn I pads at LC-34 and LC-37 at CCAFS, meaning ALL launches would have to be conducted from KSC, which the Air Force wanted no part of... (and in fairness was a rather expensive way to do it, especially for unmanned launches). The Air Force wanted a WTR capability (polar launches out of Vandenberg) which would have required all-new pad(s) out there as well if Saturn IB or a solid-boosted Saturn IB was to be the "single launcher" for most of the Air Force and NASA launches. Interestingly, the Air Force figured that they could support a solid-boosted system using either a cluster of 156 inch SRM's or an all new 15 foot diameter "super Titan" (basically, the "Barbarian" proposal) flanked by a pair of 156 inch SRM's, possibly even the NASA-developed 260 inch monolithic Aerojet SRM first stage... Cost projections showed that the differences between the proposals, in terms of operations costs, weren't really that big. The main costs would be in development-- adapting something you are already flying is cheaper than developing something completely new from scratch.

There were proposals for replacing the H-1 engines with F-1, although basically it would require a combination of F-1 and maybe the four outer H-1's to really make sense, at least with the stock F-1. In addition, the F-1's dry weight was heavier than the cluster of H-1's-- and replacing the inner four H-1's with a single F-1 would have been MUCH heavier than the cluster of H-1's. It would also require redesign of the propellant manifolds and thrust structure of the S-IB to feed an F-1 instead of four H-1's in the center. Using TWO F-1's would be a viable alternative and allow for using a single engine type (and allow the H-1 to be retired, reducing the number of "procurement programs" necessary to keep a vehicle operational) but again, would require a BIG redesign of the S-IB to accomplish-- a complete revision of the propellant ducting feeding the engines and of the thrust structure. Plus, a pair of F-1's would rapidly over-accelerate the stage as propellant burned off, and since F-1 wasn't throttleable, the only alternative I can see would be for the guidance and control system to be programmed to monitor the engines and shut one down after a minute or so of flight, well before the 2 minute mark in flight, to reduce the thrust to just the remaining firing F-1 engine. If I were designing for that, I'd have the GNC system monitoring the engines from startup to the shutdown point, and recording "points" against each engine for any off-nominal conditions that could mean trouble later on, and then when the shutdown point was reached in flight, the guidance system would then shut down the engine that had more "points" against it in startup and operation to that point. Of course the GNC system would also have to switch over to a new off-center thrust condition of the single remaining firing F-1 engine that would normally continue to burn until stage shutdown just prior to staging, but that's not particularly difficult. The other issue is, with only a single remaining F-1 firing for the second half of the first stage flight, you have no roll control with the single engine. You'd either have to have a roll-control thruster system to take over roll control at that point, , or some small vernier engines burning to provide roll control authority. Maybe the S-IVB APS thrusters could serve that function-- I don't know. But it would have to be figured out. Basically if you have to redesign the stage for all that, you'd probably not have much more work to do to redesign for unitary propellant tanks, IOW, a S-IB sized version of the S-IC's single LOX and Kerosene tanks, and an intertank between them, and ditch the cluster tank arrangement altogether. One could save weight that way, though it doesn't gain you much advantage on a first stage, and of course the redesign would be expensive. Basically there's no justification for it. Either your modifications can make use of the existing S-IB stage, or you just switch to the S-IC stage. From this study, the S-IC stage didn't seem like too expensive of an option, and it was already developed... when you figure design, development, testing, and certification costs to get it to the point that the S-IC already was at, versus perhaps slightly cheaper manufacturing and perhaps operational costs, it would take a LONG time, if ever, to make back any "savings" from a smaller unitary tank new S-IB replacement stage. For a minimal investment, you'd have MUCH better returns on a similar "simplification" program for the S-IC stage to make it cheaper to manufacture, and that way you still maintain an HLV capability at some point in the future when/if you need the capability...

Now, this does neglect one thing... the F-1A... From the studies I've read, the plan was to replace the F-1 on the second run of Saturn V's, had there been a second production run of Saturn V's... (which of course sadly there weren't). The F-1A would have increased the thrust from the 1.5 million pounds of the F-1 to 1.8 million pounds per engine... and with a turbine redesign on the turbopump, the engine could have produced over 2 million pounds of thrust. Even the 1.8 million pound thrust improvement would have allowed a substantial upgrade in capabilities to the Saturn IB stage without requiring H-1 engines at all, replacing eight 205,000 lbs thrust cluster of H-1's (total thrust of 1.64 million pounds), but it still would have required the redesign of the propellant manifolds under the stage and the thrust structure. Whether this was worth the money or not I don't know. I have a feeling that basically, other than a tank stretch to the existing Saturn IB first stage, substantial redesign simply wouldn't be worth the trouble or expense. But the F-1A seems to be the likeliest and most straightforward improvement to the S-IB.

Barring that, it seems to me that the "best" way forward would have been to pursue the development of INT-20. That would be pretty straightforward; it's basically 'de-rating' the existing Saturn S-IC stage for fewer engines and lighter loads. Since it was already developed and certified for larger loads, it would basically be a turn-key deal, more or less. It also opens the door for modest investments, like perhaps going ahead with the S-ID development of a "stage and a half" concept, which would buy even MORE performance from the INT-20 concept, and allow for a "1.5 stage to orbit" vehicle using NO upper stage, which would have been a REAL money saver for payloads in the 20-25 ton (shuttle) range, all on kerosene engines.

It's really sad to see that the goal they were pursuing, cheaper launch to space, was within their grasp, based on already developed or near-term development of existing systems and perhaps some new expendable components. Instead, politics became involved, and NASA being an engineering agency rather than an operations one, wanted the "challenge" of designing a new system, and cooked the books to get it, making all kinds of wild assumptions of cost savings to justify it. In the end, NASA got their totally new shuttle, but it turned out to more expensive than the Saturn systems they junked before they even attempted to optimize them and reduce costs. The Air Force jumped on board and then discovered the folly of the "single manned reusable launch vehicle for all payloads" approach with the Challenger disaster of January 1986. The Air Force got their big Western Test Range (WTR) pad at Vandenberg, but it was for shuttle, and never launched a single vehicle. It was eventually redesigned and modified for EELV (Delta IV heavy). Shuttle never achieved the ridiculously high flight rates required to approach anything like cost effectiveness-- in fact, it would have been just about as cheap to keep launching Saturn V's, which were WAY more powerful and much safer than the shuttle turned out to be.

All water under the bridge now... but only now are we figuring out exactly what we lost... As shuttle manager John Shannon told the Augustine Commission, "reusability is a myth" (at least the shuttle form of it) and basically expendable vehicles, not requiring refurbishment after launch (at least not extensive manpower intensive expensive refurbishment like shuttle required) is actually cheaper (which is part of the reason why the shuttle SRB casings to be used on SLS, assuming it ever flies, will be expended and dumped on the bottom of the ocean after flight rather than recovered for reuse). It remains to be seen if the SpaceX method of reusability (boost-back to vertical hover, descent, and landing) will work as advertised and be cheaper than a fully expendable booster designed for lowest cost manufacture, assembly, testing, and operations. Basically all shuttle taught us was how NOT to design a reusable vehicle, and ESPECIALLY how to not design a low-recurring cost launch vehicle...

Later! OL JR [/QUOTE]

NJRick said:

Luke,
I hear ya on the 1b and growth potential.....but you have to admit it looks cool!
seriously, I have always wondered if there was any way to squeeze more performance out of the H-1s....not sure if there was any growth left in the H-1 design. I know lifting a an Apollo CSM pretty much maxed the 1b out...but it was a reliable booster and they had the infra structure in place for it....and as you indicated earlier...it was already man-rated and a proven booster.

I think you are spot on in your point that we are only now finding out what we lost. I know it was a different time...but looking back we had two incredible boosters in place in the Saturn V and the 1b...and we just left them at the curb and walked away. just amazing.

Click to expand...

Oh yeah... the IB is about the coolest looking rocket ever... agree with you there... it's also a pretty neat solution to some interesting problems (most of them political/funding) and it's amazing how well it did work.

IIRC, the H-1's had been upgraded twice, first to 200,000 lbs thrust from the original 165,000 lbs thrust, and then to 205,000 lbs thrust in the final iteration. I don't think there was really much room for improvement beyond that; pretty much the last bit of power that could be wrung out of the design had been by that point... you can only cram SO much propellant through a given size opening, turbopump, injector, combustion chamber, etc... I think the physical size of the engine (which is actually pretty darn small when you stand next to one as I have at JSC many times) was the real and final limitation. You can increase the power through the turbopump to increase propellant volume and pressure (so long as you don't burn out the turbine or the gearboxes), change the injector design for greater efficiency or higher propellant flow rates, increase the combustion chamber pressure (so long as the combustion chamber can contain it and not explode or melt), and solve various other bottlenecks and flow inefficiencies in the engine design, but most of that had already been done. RS-27 as used on the Delta rocket was basically derived/evolved from the H-1. The original RS-27 was around 230,000 lbs thrust, RS-27A used on the later Deltas kicked that up to 240,000 at altitude with an extended nozzle. Liftoff thrust was still around 200,000 lbs at sea level though... Basically any major changes beyond the "tweaks" I already mentioned, and you're talking about a whole new engine...

Now, there was another alternative, which may or may not have been viable... scrap H-1 and revive the E-1. E-1 was the test bed predecessor to the F-1. In the late 50's when the F-1 was proposed, the engineers weren't at all confident that they could leap from an engine like the H-1, which was already pretty cutting edge for the time, to an engine nearly 10 times more powerful. Some doubted it was even possible. Many thought it a bridge too far. SO, they decided to build an engine roughly two times as powerful as H-1. This became E-1. E-1 was also a backup engine for the Titan missile, when LR-87 was still in development. E-1 was completed and test fired, and with the knowledge in hand from it, it was promptly shelved, since the LR-87 had been completed and was being used on Titan. For a time, E-1 was slated to be the engine of choice for the Saturn vehicles, but the lunar plans superseded it... These were back during the plans like "Project Horizon" where the Saturn I rocket was to grow into a whole stable of rockets for lunar operations. With Kennedy's lunar goal announcement publicly challenging the Soviets to a race to the Moon within the decade, those plans were hopelessly outdated (that and they were rather overly simplistic and optimistic as well.) It became apparent that something MUCH larger than Saturn I or even the upgraded Ib would be required, thus Saturn V was born, and Saturn I was largely passed by. E-1 sorta fell between the cracks in the handover of Von Braun's team from the Army to NASA; E-1 wouldn't be ready in time for Saturn I tests and H-1 was sufficient for the test flights the Saturn I and IB were slated for, and for the operational flights that followed (like Apollo 7, Skylab, and ASTP). There wasn't a pressing NEED for the development of a new first stage engine for Saturn IB, so it simply wasn't done. Upgrades to H-1 were sufficient, but left basically no room for growth beyond that.

E-1 tested out at about 380,000 lbs of thrust-- about 3/4 that of the hydrogen burning SSME. A cluster of four E-1's would have given a Saturn IB about 1.52 million pounds of thrust (the 8 H-1 cluster of 205,000 lb thrust each was 1.64 million pounds)-- plenty sufficient for the job to start with. Five would get you up to 1.9 million pounds of thrust. Of course there's no telling how much extra thrust could be gained by improvements to E-1 past the testing phase... That should have been plenty for anything the vehicle could reasonably do...

As to why it wasn't proposed to revive E-1 and retire H-1, I don't know. Sheer cost I'd suppose. E-1 was never really flight hardware, just a testbed AFAIK... maybe the thought process was that it would simply be too expensive to restart the E-1 and take it to the certified flight hardware stage... I don't know. It's not like such an engine wouldn't have been incredibly handy to have, or that it couldn't have found a purpose (and mated to the already existing but slightly redesigned for it Saturn IB could have kept them both at the forefront of US space launch needs for decades to come... so even if it was a healthy investment, it would have been a good one! Plus, we spent HOW MANY HUNDREDS OF MILLIONS (in then dollars) perfecting the extremely complex and touchy hydrogen burning SSME, with close to the SAME THRUST?? (though, granted, for a very different job and reusability). Remember SSME problems delayed the shuttle program for years, because they kept blowing up in the test stands and required substantial re-engineering to be made to work, delaying the first shuttle flight to 1981. The E-1 was about as simple as a rocket engine got-- a gas-generator cycle, relatively low pressure engine, basically a 2X upscale of H-1. It would have been about as close to a "turn key" engine program as you could get.

E-1 was relegated to the dustbin of history, a test article and then passed over in the quest for the much larger F-1, which would scale up from the E-1 by approximately 4 times. Anybody familiar with space history is aware of the "teething problems" that F-1 faced in its development, mostly due to its sheer size and power, primarily in the area of combustion instability. It was solved though and quite successfully. E-1 had similar problems early on.

No, it seems to me that if the Saturn IB was to continue, the most straightforward plan would have been to equip it with a single F-1A engine of about 1.8 million pounds thrust. Basically that was the thinking anyway-- E-1 wasn't deemed worth the additional money to develop due to the fact that later on the F-1 would be available and be able to deliver the same power as the four E-1 cluster anyway.

The simple fact is, NASA wasn't REALLY interested in keeping the Saturns alive, or they would have. They were FAR more interested in designing and building an all-new reusable space plane, and frankly they drank their own Kool-aid and ended up shooting themselves in the foot, especially since they weren't going to get the kind of budget to do it right, and ended up getting in bed with the Air Force (who still nurtured their own dreams of putting blue suits in orbit on their own vehicles) and the rest is history.

Later! OL JR

Some more pics relating to the original topic...

Enjoy! OL JR