| DC-X |
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Model: DC-X.
The DC-X was an experimental vehicle, 1/3 the size of a planned DC-Y vertical-takeoff/vertical-landing, single stage to orbit prototype. It was not designed as an operational vehicle capable of achieving orbital flight. Its purpose was to test the feasibility of both suborbital and orbital reusable launch vehicles using the VTOVL scheme. The DC-X flew in three test series. The first series ran from August 18 to September 30, 1993, before the initial project funding ran out in late October 1993. Additional funding was provided and a second series was conducted June 1994-July 1995. The Single Stage Rocket Technology program was an SDIO (Space Defense Initiative Office) programme to demonstrate technology readiness for an SSTO vehicle. The SDIO (Strategic Defense Initiative Organization) issued a call for proposal for design studies of a single stage to orbit launch vehicle in August 1990. Six companies responded, four proposing vertical takeoff concepts (McDonnell-Douglas, Rockwell, General Dynamics and Boeing) and two proposing air-launched concpets (Grumman and Third Millennium). A total of $ 12 million in study contracts were awarded to the four companies proposing VTO designs, reflecting SDIO's preference for VTOL concepts studied in an Aerospace Corporation report of the previous year. Douglas and General Dynamics proposed VTOVL designs. Boeing's final design was an improved version of its HTHL sled- or rail-launched RASV (Reusable Aerodynamic Space Vehicle) powered by uprated Shuttle Main Engines. Rockwell proposed a VTHL vehicle, similar in layout to the Space Shuttle Orbiter, but with an aerospike engine. Phase II of the program would consist of fabrication of an 'X' subscale demonstrator and design of a 'Y' prototype vehicle. Reflecting SDIO's predilections, Douglas was finally awarded the $60 million Phase II contract The Douglas DC-X was designed primarily to validate the turnaround and landing maneuver required for the company's complex nose-first entry concept (as opposed to the base entry approach of prior VTOVL SSTO designs). This approach would, the company believed, provide a wide cross range, always attractive to the Air Force for operational reasons. In commercial applications nose-first entry would reduce the loads experienced by the crew and passengers to under 2G, compared with 3G for base-first lifting entries. The DC-X was specifically not designed to demonstrate the most critical issue for any practical SSTO: structural mass fraction Under a 2-year, $58-million Phase II contract, MDSSC and its team-mates were using a rapid prototype approach to design and build a one-third-size experimental vehicle the DC-X, and ground support and operations systems which, through a series of suborbital flights, was to:
The SSRT program consists of three phases. Phase I began in August 1990 and consisted of a $12 million design and risk reduction competition. At that time, the program was focused on multiple single stage-to-orbit concepts which were found to be potentially viable, including vertical take off and landing (VTOL), horizontal takeoff and landing (HTOL) and vertical takeoff and horizontal landing (VTHL) configurations. Following completion of Phase I, a two-year $58 million Phase II contract was competitively awarded to McDonnell Douglas Aerospace, Huntington Beach, Calif., in August 1991. The program was subsequently restructured and focused on building the DC-X and enabling suborbital RLVs for potential use by BMDO. The DC-X design emphasised simplified ground and flight operations, vehicle maintenance, rapid turnaround, and operational characteristics that were also relevant to future orbital vehicles. For example, the highly automated control centre for this system was manned by only three people: two for flight operations and one for ground operations and servicing. Successful completion of the DC-X testing in mid 1993 was to form the basis for a Phase III "go/no go" decision by the Department of Defense to develop a follow-on Advanced Technology Demonstrator for support of flight tests and experiments. If a decision was made to proceed with Phase III, the program was to be transferred to another agency. A systems ground test facility was activated at NASA's White Sands Test Facility (WSTF), and a launch and recovery site at WSMR. The completed DC-X vehicle was tested on a modified propulsion test stand at the WSTF prior to flight testing at WSMR. Maintenance and ground support techniques required for the flight test phase of the program was to be tested, evaluated and refined at WSTF. The aircraft-like flight test program was to began with low altitude hover flights, gradually increasing in altitude and duration, and was to lead to suborbital flights to approximately 5500 m. Funding was stop-and-go however. By July 1995 the DC-X had completed eight flights in two series, reaching 2500 m. On the eighth flight the aeroshell was cracked in a hard landing. It was decided to return the vehicle to the Huntington Beach factory for repair and modification to the Delta Clipper Experimental Advanced (DC-XA) configuration. The DC-XA was operated by NASA and the Department of Defense under the Reusable Launch Vehicle program. This had a lightweight graphite-epoxy liquid hydrogen tank and an advanced graphite/aluminium honeycomb intertank built by McDonnell Douglas; an aluminium-lithium liquid oxygen tank built by Energia (Russia); and an improved reaction control system from Aerojet. These improvements reduced dry vehicle mass by 620 kilograms. The flight vehicle, bizarrely renamed by NASA 'Clipper Graham', was tested at White Sands during the summer of 1996, and demonstrated a 26-hour turnaround between its second and third flights, a first for any rocket. After the fourth flight, however, the DC-XA suffered severe damage and the program ended due to lack of funding. Program Manager for the original SSRT Program was Major Jess Sponable, U.S. Air Force. The prime contractor was McDonnell Douglas Aerospace, Huntington Beach, Calif. The Delta Clipper industrial team consisted of:
The Chief Technical Advisor for the DC-X has noted that reusable launchers, by their nature have intact abort and that do not crash - they have mishaps not failures. Even the several fires and one auto-abort were not flight test failures. In fact, the auto-abort mishap was the first time that a rocket powered unmanned vehicle had ever saved itself from a fiery death. Even the final test which destroyed the vehicle, met all test objectives and had achieved full engine shut-down prior to the one landing gear collapse (due to a very tired, heat exhausted human technician error). Manufacturer: Douglas. Launches: 12. Failures: 1. Success Rate: 91.67%. First Launch Date: 1993-08-18. Last Launch Date: 1996-07-31. Launch data is: complete. Apogee: 3.00 km (1.80 mi). Liftoff Thrust: 223.000 kN (50,132 lbf). Total Mass: 16,320 kg (35,970 lb). Core Diameter: 3.05 m (10.00 ft). Total Length: 14.00 m (45.00 ft). Span: 4.10 m (13.40 ft). Development Cost $: 58.900 million. in: 1991 average dollars. Total Development Built: 1. in: 1991 unit dollars. Cost comments: Cost is for single prototype built.
Model: DC-XA. After a hard landing in the last flight of this series, the vehicle was rebuilt to the DC-XA configuration. The DC-XA flew from May 1996 until destroyed when it tipped over while landing on its fourth flight on 31 July 1996.
Launches: 4. Failures: 1. First Launch Date: 1996-05-18. Last Launch Date: 1996-07-31. Apogee: 10 km (6 mi). Liftoff Thrust: 242.000 kN (54,403 lbf). Total Mass: 19,000 kg (41,000 lb). Core Diameter: 4.95 m (16.24 ft). Total Length: 12.60 m (41.30 ft).
DC-X Chronology 1993 August 18 - 22:43 GMT - White Sands -. Agency: MDAC. Apogee: 0 km ( mi). Verified flight control systems and vertical landing capabilities. Reached 46 m altitude in a 59 second flight. 1993 September 11 - 17:12 GMT - White Sands -. Agency: MDAC. Apogee: 0 km ( mi). Ascent and landing mode control and ground effects survey. Reached 92 m in a 66 second flight. 1993 September 30 - 16:28 GMT - White Sands -. Agency: MDAC. Apogee: 0 km ( mi). Demonstrated 180 degree roll; provided aerostability data. Reached 370 m during 57 second flight. Last test of first series -- vehicle mothballed when SDIO funding ran out. 1994 June 20 - 14:42 GMT - White Sands -. Agency: MDAC. Apogee: 1.00 km (0.60 mi). First flight of second series after additional SDIO funding received. Full propellent load; radar altimeter in control loop. Reached altitude of 870 m during a 136 second flight. 1994 June 27 - 14:36 GMT - White Sands -. Agency: MDAC. Apogee: 0 km ( mi). In-flight abort after gaseous hydrogen explosion; vehicle demonstrated autoland capabilities. Reached altitude of 790 m during a 78 second flight. 1995 May 16 - 15:40 GMT - White Sands -. Apogee: 1.00 km (0.60 mi). Continued expansion of flight envelope; constant angle of attack. Reached altitude of 1330 m during a 124 second flight. 1995 June 12 - 14:38 GMT - White Sands -. Apogee: 1.00 km (0.60 mi). First use of reaction control system thrusters; demonstrated change of angle of attack from 0 to 70 degrees. Reached altitude of 1740 m during a 132 second flight. 1995 July 7 - 13:02 GMT - White Sands -. Apogee: 2.00 km (1.20 mi). Final flight of second series. Demonstrated turnaround maneuver. Aeroshell cracked during 4 m/s hard landing. Reached altitude of 2500 m during a 124 second flight. 1996 March 15 - White Sands -. DC-XA DC-XA Rollout 1996 March 22 - White Sands -. DC-XA DC-XA arrives at White Sands 1996 May 4 - White Sands -. DC-XA DC-XA Engine Test 1 1996 May 7 - White Sands -. DC-XA DC-XA Engine Test 2 1996 May 18 - 14:20 GMT - White Sands -. Apogee: 0 km ( mi). First flight of the DC-XA; aeroshell caught fire during slow landing. Reached altitude of 244 m during a 62 second flight. 1996 June 7 - 16:15 GMT - White Sands -. Apogee: 0 km ( mi). Maximum structural stresses with 50% full LOX tank. Reached altitude of 590 m during a 64 second flight. 1996 June 8 - 18:17 GMT - White Sands -. Apogee: 3.00 km (1.80 mi). 26-hour rapid turnaround demostration; new altitude and duration record. Reached altitude of 3140 m during a 142 second flight. 1996 July 31 - 19:15 GMT - White Sands -. FAILURE: Landing strut 2 failed to extend; vehicle tipped over and LOX tank exploded; vehicle destroyed. Apogee: 1.00 km (0.60 mi). Reached altitude of 1250 m during a 140 second flight.
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