The Saturn-Shuttle was a proposed interface of the Space Shuttle

Space Shuttle

The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

 orbiter and external tank with the S-IC

S-IC

The S-IC was the first stage of the Saturn V rocket. The S-IC first stage was built by The Boeing Company. Like the first stages of most rockets, most of its mass of over two thousand metric tonnes at launch was propellant, in this case RP-1 rocket fuel and liquid oxygen oxidizer...

 stage on the Saturn V

Saturn V

The Saturn V was an American human-rated expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. A multistage liquid-fueled launch vehicle, NASA launched 13 Saturn Vs from the Kennedy Space Center, Florida with no loss of crew or payload...

 rocket. An interstage would be fitted on top of the S-IC

S-IC

The S-IC was the first stage of the Saturn V rocket. The S-IC first stage was built by The Boeing Company. Like the first stages of most rockets, most of its mass of over two thousand metric tonnes at launch was propellant, in this case RP-1 rocket fuel and liquid oxygen oxidizer...

 stage to support the external tank, formerly occupied by the S-II

S-II

The S-II was the second stage of the Saturn V rocket. It was built by North American Aviation. Using liquid hydrogen and liquid oxygen it had five J-2 engines in a cross pattern...

 stage, so that NASA would have been able to steer completely away from solid rockets

Space Shuttle Solid Rocket Booster

The Space Shuttle Solid Rocket Boosters were the pair of large solid rockets used by the United States' NASA Space Shuttle during the first two minutes of powered flight. Together they provided about 83% of liftoff thrust for the Space Shuttle. They were located on either side of the rusty or...

. The addition of wings on the S-IC stage would allow the booster to fly back to the Kennedy Space Center

Kennedy Space Center

The John F. Kennedy Space Center is the NASA installation that has been the launch site for every United States human space flight since 1968. Although such flights are currently on hiatus, KSC continues to manage and operate unmanned rocket launch facilities for America's civilian space program...

 in which the technicians would then refurbish the booster (by replacing only the five F-1

F-1 (rocket engine)

The F-1 is a rocket engine developed by Rocketdyne and used in the Saturn V. Five F-1 engines were used in the S-IC first stage of each Saturn V, which served as the main launch vehicle in the Apollo program. The F-1 is still the most powerful single-chamber liquid-fueled rocket engine ever...

 engines and reusing the tanks and other hardware for later flights).

Performance

Because the Shuttle orbiter would be riding piggyback on the External Tank, and the need to prevent damage to the delicate thermal protection tiles, the five-engine variant of the Saturn-Shuttle would require the center engine to be shut down 45 to 50 seconds after launch, while two of the outboard engines would have to be shut down prior to staging. Once the S-IC was jettisoned, the three onboard high-energy SSMEs would then propel the Orbiter into LEO, shutting down 6½ minutes after ignition. The external tank would then be jettisoned, as on the current Shuttle configuration and the Orbiter will then perform its mission.

But because of the need to keep costs down and to allow President Richard Nixon

Richard Nixon

Richard Milhous Nixon was the 37th President of the United States, serving from 1969 to 1974. The only president to resign the office, Nixon had previously served as a US representative and senator from California and as the 36th Vice President of the United States from 1953 to 1961 under...

 to approve the Shuttle program in 1972, NASA decided to utilize segmented Solid Rocket Boosters similar to those used on the Titan III

Titan III

The Titan IIIC was a space booster used by the United States Air Force. It was launched from Cape Canaveral Air Force Station, FL., and Vandenberg Air Force Base, CA. It was planned to be used as a launch vehicle in the cancelled Dyna-Soar and Manned Orbiting Laboratory programs...

rocket instead of the S-IC, thus ending the Saturn program after the initial Saturn V order was completed.