Model, Space Shuttle, Grumman 2-Stage SRB Parallel Burn Concept, 1:192

NASA studied this concept for a partially reusable space transportation system during the Shuttle research effort in 1969-1972. This two-stage system featured two solid rocket boosters (used as a 1st stage) and a delta-wing fly-back orbiter with engines fed by an external liquid propellant tank (used for both stages of ascent). Both the boosters and external tank would be jettisoned when their propellants were expended, but the boosters would be recovered and reused. NASA transferred a variety of concept models to the Museum after settling on the final Space Shuttle design, which was similar to this concept.