The Saturn-Shuttle was a preliminary concept of launching the Space Shuttle orbiter using a modified version of the first stage of the Saturn V rocket.

[2] An interstage would be fitted on top of the S-IC stage to support the external tank in the space occupied by the S-II stage in the Saturn V. It was an alternative to the SRBs.

[1] Some studies proposed the addition of wings (and some form of landing gear) to the S-IC stage, which would allow the booster to fly back to the Kennedy Space Center, where technicians would then refurbish the booster (by replacing only the five F-1 engines and reusing the tanks and other hardware for later flights).

[1] The Shuttle would handle space station logistics, while the Saturn V would launch components.

This would have allowed the International Space Station, using a Skylab or Mir configuration with both U.S. and Russian docking ports, to have been lifted with just a handful of launches.