DBWI: STS Engines Mounted on the Orbiter?

[Bahamut-255]

It hasn't been that long since the 33-year life of the Space Transportation System (STS) came to an end, so I believe that this is a good time to ask this question.

Looking into its history, there appears to have been a very serious debate over where to place the RS-25 engines, with some advocating placing them on the Orbiter itself to permit their reuse after each mission, while others (who won out IOTL) sought to place them on what became the Core Stage to lighten the Orbiter and increase the payload capability.

So the obvious question is: What would be the case, had the engines been mounted on the Orbiter?

 

[NOLAWildcat]

I'd imagine the mission turnaround time on each orbiter would be even longer than what we historically saw. Remember NASA sold Congress on the STS as a reliable, reusable way of maintaining space access while increasing the number of launches to as many as once every two weeks. In practice, NASA struggled to get a launch off every month, and that during high periods of activity. The placement of the RS-25 engines in the orbiter may have made passage of the funding for STS less hairy (Mondale and Proxmire nearly sank the project by using the argument that the Core Stage engines required heavy refurbishing following their sea recovery) but I imagine the added time needed to inspect the RS-25 engines after every mission would slow the turnaround time enough to outweigh the cost benefits over refurbishing the RS-25s in the recoverable Core stage. Not to mention the payload hit the Orbiter would have taken by having to haul the weight of several RS-25s in the airframe, reducing the usefulness of the STS to the Air Force's spy satellite program based out of Vandenberg.

Of course, the placement of the RS-25s in the orbiter may have prevented the Atlantis disaster in 1987. Regardless, it's an interesting POD that may have major butterflies on the development of the Capricorn next-gen STS in the 1990's.

 

[Bahamut-255]

I'd imagine the mission turnaround time on each orbiter would be even longer than what we historically saw. Remember NASA sold Congress on the STS as a reliable, reusable way of maintaining space access while increasing the number of launches to as many as once every two weeks. In practice, NASA struggled to get a launch off every month, and that during high periods of activity. The placement of the RS-25 engines in the orbiter may have made passage of the funding for STS less hairy (Mondale and Proxmire nearly sank the project by using the argument that the Core Stage engines required heavy refurbishing following their sea recovery) but I imagine the added time needed to inspect the RS-25 engines after every mission would slow the turnaround time enough to outweigh the cost benefits over refurbishing the RS-25s in the recoverable Core stage. Not to mention the payload hit the Orbiter would have taken by having to haul the weight of several RS-25s in the airframe, reducing the usefulness of the STS to the Air Force's spy satellite program based out of Vandenberg.

Of course, the placement of the RS-25s in the orbiter may have prevented the Atlantis disaster in 1987. Regardless, it's an interesting POD that may have major butterflies on the development of the Capricorn next-gen STS in the 1990's.

OOC: Check the OP, where I said that the placing the engines in the Orbiter would permit their reuse, meaning that they're expended in the Core Stage.


IC: As for the 1987 Atlantis Disaster, it took them a while to get it going again, given the work needed to shift the engines further from the SRBs to mitigate that risk, amongst many other design changes to further stifle failure.

 

[NOLAWildcat]

OOC - My bad, I read the OP as allowing for the RS-25s to be reusable as part of a reusable Core Stage a la OTL's SRBs rather than a totally expendable system like the Apollo's F-1 engines. Of course, much of the RS-25's complexity stems from the need to have them mounted to the Orbiter. In all seriousness, I'd think that NASA would be more likely to adapt a variant of the F-1 engine for use in an expendable Core Stage rather than go through the costly development of the RS-25s.

 

[Drunkrobot]

Would it have any ramifications on Energia/Buran? Yes, Buran itself was a fancy copy of the Shuttle design, and would only get about five flights to Mir before being grounded when the USSR collapsed, but it got Glushko's baby into service (dem RD-170s) and hauling those massive cores of the Multinational Space Station into orbit arguably saved the Russians from losing their manned space capabilities.

And, of course, there's the return to the Moon set for before 2020. Unless something happened to kick either America or the Soviet Union square in the nuts and get them working towards the Moon again, I don't think many projects are possible that could get men back on that rock without either those engines or R&D based on those engines.

 

[NOLAWildcat]

KGB Role in Buran/Energia development

It's possible that had Rockwell designed the Shuttle Orbiter with RS-25s mounted to the airframe rather than having McDonnell-Douglas incorporate them into the Core Stage design, the Soviets would have opted to design the Buran airframe with integral main engines rather than depending on the Energia alone to provide the necessary thrust at launch.

 

[e of pi]

Would it have any ramifications on Energia/Buran? Yes, Buran itself was a fancy copy of the Shuttle design, and would only get about five flights to Mir before being grounded when the USSR collapsed, but it got Glushko's baby into service (dem RD-170s) and hauling those massive cores of the Multinational Space Station into orbit arguably saved the Russians from losing their manned space capabilities.

Given that the only changes that Buran saw from the American system in general concept was that ability to be flown without the spaceplane (which I'm sure the Americans would have eventually done anyway--they were talking about it in studies even before Buran was revealed to the West) and the LRB vs SRB issue, I think Buran would be largely the same. Actually, I wonder if Energia might have ended up better off--the last few flights in the late 90s that carried the cores for MSS before Shuttle-C entered service showed some potential for the system, but then the similar sidemount cargo configuration of Shuttle-C took over the whole role, and eventually heavy lift for lunar return. Without it, maybe they'd be force to depend on the Russians and Energia for heavy lift--might have been enough to save Buran ITTL?

OOC: The cores of an ISS-like station are unlikely to fly much before the end of the 90s. Thus, I'm taking this that there's a stronger Energia/Buran split ITTL, and though Buran only flew a few times, Energia flew a couple more on its own before the Americans complete ripping the idea back off the Russians.

 

[Bahamut-255]

Given that the only changes that Buran saw from the American system in general concept was that ability to be flown without the spaceplane (which I'm sure the Americans would have eventually done anyway--they were talking about it in studies even before Buran was revealed to the West) and the LRB vs SRB issue, I think Buran would be largely the same. Actually, I wonder if Energia might have ended up better off--the last few flights in the late 90s that carried the cores for MSS before Shuttle-C entered service showed some potential for the system, but then the similar sidemount cargo configuration of Shuttle-C took over the whole role, and eventually heavy lift for lunar return. Without it, maybe they'd be force to depend on the Russians and Energia for heavy lift--might have been enough to save Buran ITTL?

OOC: The cores of an ISS-like station are unlikely to fly much before the end of the 90s. Thus, I'm taking this that there's a stronger Energia/Buran split ITTL, and though Buran only flew a few times, Energia flew a couple more on its own before the Americans complete ripping the idea back off the Russians.

That's a good point, IIRC, having that capability made the idea of a large central core section(s) appealing and designs started to use them as the critical element. Still, at least Energia was able to close on a high, being one of only two LVs with 100% launch success rate (when excluding payloads themselves), so it did justify the intensive ground tests it received prior to its first flight.

Could have saved Buran itself, given it was basically an updated variant of STS.


OOC: Liking that idea E of Pi, NASA reverse-copying from the Russians. Almost Karmic.