DM-F3

The third and final flight of the Delta III, carrying only a dummy payload of steel and aluminum sized to mimic a Hughes HS-601 satellite, after the rocket's first two flights with real spacecraft both failed. The second-stage RL10 engine suffered a chamber rupture and shut down early, leaving the mass model in too low an orbit. It was the closest the troubled vehicle ever came to success, and Boeing retired the design soon after.