DC-Y Credit - NASA

The ultimate goal of the Delta Clipper program, a prototype reusable single-stage to orbit, vertical takeoff/vertical landing space truck. The DC-I Delta Clipper would be the full production version. No government sponsor could be found for the concept and the $ 5 billion development cost was never funded. If it had been funded in 1991, the first DC-Y suborbital flight was predicted for 1995, and a first orbital mission in 1997.

The Delta Clipper was envisioned as a spaceship that could take off straight up and land the same way, not gliding but under power, just like the rocket-ships in the 1950's science-fiction movies. Because of its improved engines, high-tech light-weight materials, and airline-like service procedures, the Delta Clipper could reduce the cost of getting to and from space by 90% or greater. Because it was to be certified for flight like an aircraft, it was to be able to operate from spaceports located in any state. The production Delta Clipper was expected to carry two crew members and 10 tons of cargo and/or passengers to Low Earth Orbit or 2 crew members and 5 tons of cargo/passengers to Polar Orbit. The anticipated turn-around time for the Delta Clipper was a maximum of seven days. However, a one day turnaround was hoped to be feasible.

The production model Delta Clipper was to be conical shaped, approximately 40 m high and 12 m across the base. It was to have eight or more rocket engines, providing safe return engine out capability like any airliner. The Delta Clipper was to not have wings like the Shuttle but was to use small moveable flaps to help manoeuvre. It was to not require strap-on external tanks or boosters.

The production Delta Clipper would enable any state in the Union to have its own spaceport. Unlike the Shuttle, the Delta Clipper wouldn't need a long runway, huge Vehicle Assembly Building, or Mission Control but only a 60 m diameter concrete pad, a maintenance hangar, and a hydrogen/oxygen fuel facility. It was to use existing global positioning satellites for navigation.

The total cost of developing the first flight certified Delta Clipper was to be comparable to or less than the development of a new commercial airliner. Total cost for the development of the DC-Y prototype program was estimated at $5.06 billion, including production of four flight vehicles. The ticket price for early versions of the Delta Clipper, if it met cost goals, could be less then the price for a round-the-world cruise on the QE2 ($40,000 to $140,000). A second generation vehicle could further reduce this cost. Once fully operational the Delta Clipper was to be as safe as flying on a typical commercial airliner. Delta Clipper was to have engine out and all altitude abort capability. Plans were to have the Delta Clipper certified by the Department of Transportation, Office of Commercial Space flight.

The Delta Clipper was to burn only hydrogen and oxygen. Its exhaust consists primarily of pure water vapour. Therefore it was not expected to produce air pollution or disturb the ozone layer. Since the Delta Clipper launches straight up, the sonic boom would be largely restricted to the spaceport area. When landing, the Delta Clipper was to slow down to sub-sonic speed at about 70,000 feet altitude, thus minimising the sonic boom to a barely audible level.

The eight engines for the DC-Y were to use off-the-shelf technology as much as possible. The LOX turbopump was the Fiat Avio - HM60 which was being flown on the Ariane. The Hydrogen Turbopump was from the P&W XLR- 129. The controls and health montioring system was based on a P&W system developed for NASP. The thrust chamber assembly was based on a program run out of Marshall. It used a copper tubular chamber based on P&W IR&D. The Regenerator was to be new. The extendable nozzle was based on the existing RL-10. Engine valves were from the Fiat HM60. The engine was throttable from 10% to 100% and used an expander cycle.

Manufacturer: Douglas. LEO Payload: 4,500 kg (9,900 lb). to: 300 km Orbit. at: 90.00 degrees. Payload: 9,000 kg (19,800 lb). to a: maximum payload 28 deg orbital trajectory. Associated Spacecraft: DC-Y. Liftoff Thrust: 5,330.200 kN (1,198,277 lbf). Total Mass: 470,000 kg (1,030,000 lb). Core Diameter: 9.15 m (30.01 ft). Total Length: 46.00 m (150.00 ft). Span: 12.20 m (40.00 ft). Launch Price $: 350.000 million. in: 1991 price dollars. Cost comments: Launch price is alleged price for reusable production vehicle.

• Stage Number: 1. 1 x Stage: DC-I. Gross Mass: 470,000 kg (1,030,000 lb). Empty Mass: 36,000 kg (79,000 lb). Thrust (vac): 6,860.000 kN (1,542,180 lbf). Isp: 425 sec. Burn time: 260 sec. Isp(sl): 330 sec. Diameter: 9.15 m (30.01 ft). Span: 9.15 m (30.01 ft). Length: 38.72 m (127.03 ft). Propellants: Lox/LH2. No Engines: 1. Engine: Plug-Nozzle J-2. Status: Study 1993.

• Stage Number: 1. 1 x Stage: DC-Y. Gross Mass: 84,000 kg (185,000 lb). Empty Mass: 6,000 kg (13,200 lb). Thrust (vac): 1,051.200 kN (236,319 lbf). Isp: 373 sec. Burn time: 271 sec. Isp(sl): 316 sec. Diameter: 5.00 m (16.40 ft). Span: 5.00 m (16.40 ft). Length: 20.00 m (65.00 ft). Propellants: Lox/LH2. No Engines: 16. Engine: RL-10A-5. Status: Study 1993.

• Aviation Week and Space Technology, "Single Stage to Orbit", 1991-08-26, page 15..