Studied in 1968 by Marshall Space Flight Center

Marshall Space Flight Center

The George C. Marshall Space Flight Center is the U.S. government's civilian rocketry and spacecraft propulsion research center. The largest center of NASA, MSFC's first mission was developing the Saturn launch vehicles for the Apollo moon program...

, the Saturn V-B was considered an interesting vehicle concept because it nearly represents a single-stage to orbit booster, but is actually a stage and a half booster just like the Atlas

Atlas (missile)

The SM-65 Atlas was the first intercontinental ballistic missile developed and deployed by the United States. It was built for the U.S. Air Force by Convair Division of General Dynamics at the Kearny Mesa assembly plant north of San Diego, California...

. The booster would achieve liftoff via five regular 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; four of the five engines on the Saturn V-B would be jettisoned and could be fully recoverable, with the sustainer stage on the rocket continuing the flight into orbit. The rocket could have had a good launch capability similar to that 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...

if it was constructed, but it never flew.