jimfromnsf:<br />Completely wrong! <br />No shuttle, no shuttle-C. shuttle-C only existed because it used elements of the orbiter. No orbiter, no shuttle-C.<br /><br />Me:<br />The shuttle "C" that we came to know was derived in part from orbiter components, particularly the boattail section. These were components that could have been designed without an orbiter had a shuttle "C" been designed in 1979 rather than 1989. The shuttle "C" if totally dependant on orbiter flights as you say, could not have existed for long before running out of orbiter parts. Only five operational orbiters have ever been built and Endevour was built from the remaining spares plus some parts not built under the original shuttle contract. Where would shuttle "C" have gotten orbiter parts once these production parts were depleted?<br /><br />More importantly, a design very similar to shuttle "C" could have existed in 1979 had NASA so chosen and as evidenced by the 1977 Boeing study. In that study, Boeing proposed using SSMEs on a recoverable boat tail. If they decided not to depend on orbiter produced components. A slightly modified boattail could have been built housing two Saturn-V F-1 engines as an example.<br /><br />Payload capacity of early shuttle flights, indeed as it has turned out, many shuttle flights, are well below what the shuttle initially offered. There were a few missions flown by shuttle that deployed multiple satellite payloads that otherwise would have required individual Delta rockets. Of course, in hindsight, individual Delta rockets would still have been less expensive. Certainly the Titan-IV could have been developed earlier. This post is all about hypotheticals and I agree, expendables of the time could have still been used even if more of them were required. But at the same time, a shuttle vehicle derived payload pod could have been developed completely independant of the orbiter which would have in effect, killed two birds with one stone. Having the shuttle, and having Satu <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>