Douglas/Bono 1963 concept for a chemical-boosted / nuclear upper stage launch vehicle, designed as alternatives to the Convair/Ehricke Helios. The baseline version used a nuclear, recoverable upper stage boosted above the atmosphere by a minimum chemical stage.

Manufacturer: Douglas. LEO Payload: 454,500 kg (1,002,000 lb). to: 325 km Orbit. Liftoff Thrust: 44,535.700 kN (10,012,024 lbf). Total Mass: 3,275,400 kg (7,221,000 lb). Core Diameter: 24.40 m (80.00 ft). Total Length: 52.00 m (170.00 ft).

DAC Helios ISI. Status: Study 1963.

As the basic design, but featuring an Improved Specific Impulse chemical stage that used many engines feeding into single large nozzle.

LEO Payload: 454,500 kg (1,002,000 lb). to: 325 km Orbit. Liftoff Thrust: 39,955.800 kN (8,982,421 lbf). Total Mass: 2,948,400 kg (6,500,100 lb). Core Diameter: 24.40 m (80.00 ft). Total Length: 60.00 m (196.00 ft). Flyaway Unit Cost $: 105.700 million. in: 1985 unit dollars.