Diagram of one of the proposed second generation of Space Shuttles, the Shuttle II. This plan includes liquid fuel rocket boosters to replace the solid rocket boosters. Revised shuttle layout with a detachable escape module for the crew.

Date: late 1980s

“A Shuttle II Orbiter Approaches a Space Platform

Conceptual design of a new manned space transportation system called Shuttle II is underway at the NASA Langley Research Center. Launched vertically as a two-stage rocket, Shuttle II uses [an] unmanned winged booster in the early stage of flight. The booster glides back to the launch site to be reused while the orbiter, shown here, continues onto orbit. The wingtip fins eliminate the need for a larger vertical tail allowing the use of a large payload canister on the top of the orbiter. In this case, payload is being unloaded from the rear of the canister.

Designed to begin operations in the post 2000-time frame, Shuttle II will have three primary missions: people transport, small payload launch and recovery, and on-orbit servicing. Stressing full reusability of components and greatly simplified operations, Shuttle II has a main goal [of] low-cost manned access to space in a routine, safe, and reliable manner.”

Heavy Lift Orbiter II concept art.

Cutaway of the proposed Shuttle II for NASA by Frassanito & Associates. Features about this proposal include:

A separable cockpit for use in emergencies (a concept given study in the wake of Challenger disaster)

Separate liquid hydrogen drop tanks above the wings

No boosters, but instead LH2/LOX engines mounted under the ET

Date: 1989

Concept art of the proposed Shuttle II.