The Saturn-Shuttle was a preliminary concept of launching the Space Shuttle orbiter using the Saturn V rocket. 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, so that NASA would have been able to steer completely away from solid rockets. The addition of wings on the S-IC stage 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).