In article ,
says...

Were liquid flyback boosters for the Shuttle ever realistic?

YES

http://www.ok1mjo.com/all/ostatni/sp...98377 048.pdf

Recovery costs would be dramatically reduced, along with
propellant costs. LOX is $0.10 per kg and Kerosene is $0.40
per kg, whilst Polybutadiene and Ammonium Perchlorate costs
well over $2 per kg. Recovery from the sea, versus landing
at an airport, makes the SRBs way more costly than LRBs, the
SRB has far lower performance than the LRB with the LRB
being nearly twice as efficient, the cost of refuelling and
handling the SRB is 10s times more costly than LRB, the
ability to throttle the LRB makes things far safer for the
LRB than the SRB, structure weight is far lower for the LRB
than the SRB, increasing payload to orbit, haha - this is
just the short list.


You are completely ignoring development costs. NASA never received
development funding for liquid fly-back boosters. And with NASA's cost
models (especially back then), it would have cost many billions of
dollars to develop. The politicians were never willing to fund that
kind of development, especially with the huge political support that
ATK has always enjoyed.

Supporting SRBs also meant indirect support for the supply chain
necessary to develop and produce next generation ICBMs. Politically, it
was hard to disentangle the shuttle program from the support of that
supply chain. This was not something expressed loudly in the press, but
I am arguing the pressure was there, behind closed doors.

Jeff
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