DC-X Background

August 14th, 1993


Copyright 1993 by Henry Vanderbilt and Space Access Society.

This is a companion piece to our more-or-less weekly "DC-X Update". We're splitting this off for the convenience of those who've already seen the background material. The background material will occasionally be updated; most recent change dates for both the Hardware and Politics sections are included.

[Apologies for the delay in posting; this was written Saturday 8/14, but we later discovered that it vanished on its way to the rest of the net. -HV-]

DC-X Hardware Background

(last changed August 6th 1993)

DC-X is a low-speed flight regime testbed for a proposed reusable rocket- powered Single Stage To Orbit (SSTO) transport, McDonnell-Douglas Aerospace's "Delta Clipper". DC-X is intended to prove out rocket-powered vertical takeoff, nose-first lifting-body to tail-first flight transition, and tail- first landing. It is also intended to prove out rapid turnaround of a reusable rocket by a minimal ground support crew. DC-X is being tested and flown by approximately thirty people.

DC-X has already pretty much proved out rapid low-cost development of an advanced aerospace X-vehicle type engineering testbed by a small highly- motivated engineering team on a tight budget. DC-X was built by less than two hundred people, in less than two years, for about $60 million. Of course, this sort of thing has been done before -- just not recently.

DC-X stands 40 feet tall, is 13 feet across the base, and is roughly cone- shaped, with a circular cross-section forward blending into a square base. The vehicle has four maneuvering flaps, one set into each side near the base, and sits on four landing legs. DC-X masses 22,300 lbs empty and 41,630 lbs fully fuelled, and is powered by four 13,500 lb thrust Pratt & Whitney RL-10- A5 liquid oxygen/liquid hydrogen rocket motors, each able to gimbal +- 8 degrees. The RL-10-A5 is a special version of the RL-10-A designed for wide throttling range (30% to 100%) and sea-level operation.

The single DC-X vehicle was officially rolled out of its construction hangar at MDA's Huntington Beach CA plant at the start of April, then trucked out to White Sands, New Mexico for ground and then flight tests.

Between Thursday, May 20th and Thursday, June 17th, DC-X underwent a series of nine engine firings/vehicle systems exercises, including two firings in one day with complete defueling/vehicle servicing/refueling in between.

On Friday, June 18th, the DC-X crew began breaking down the ground support equipment and moving it to the White Sands Missile Range (WSMR) flight test site, a distance of about fifty miles. Meanwhile DC-X was stored in a hangar.

On Friday, July 16th, the ground support equipment move was completed. DC-X was taken out of storage, trucked out to the flight test site, and hoisted upright onto its launch pad.

On Monday, July 19th, the DC-X crew began running a series of ground tests to make sure everything had made it over intact and was hooked back together properly.


DC-X Followon: Political Background

(last changed August 6th 1993)

The current DC-X program is funded through flight test and data analysis this fall, and ends after that. There is an ongoing effort to get the US Congress to fund a three-year followon program, currently called SX-2 (Space Experimental 2). This tentatively looks like being a reusable suborbital vehicle powered by 8 RL-10-A5 engines, capable of reaching Mach 6 (about 1/4 orbital velocity) and 100 miles altitude, built with orbital-weight tanks and structure, and able to test orbital grade heat-shielding.

The SX-2 program goal will be to demonstrate all remaining technology needed to build a reusable single-stage-to-orbit vehicle. Once SX-2 has been tested, all that should be necessary to produce a functioning reusable SSTO is to scale up the SX-2 structures and install new larger rocket engines.

Proposed FY '94 funding for SX-2 startup is $75 million. Total SX-2 program cost over the next three years would be very much dependent on the contractor chosen and the details of the design, but would be on the order of several hundred million. This is the same order of magnitude as typical recent X- aircraft programs such as the X-29 and X-31.

The $75 million SX-2 startup money now looks like being added to the Advanced Research Project Agency (ARPA) budget, with at least some of the funding in following years to come from other interested arms of the government. SX-2 would still be run by the current BMDO (formerly SDIO) DC-X management team, even though funded via ARPA, at least under the current House version of the FY '94 Defense Authorization Bill.

The House of Representatives now seems favorably disposed toward SX-2. The biggest hurdle ahead this year will probably be convincing the Senate to go along when the House-Senate conference committee meets to work out the differences between the two versions of next year's Defense budget.

 ** This is the section of the House Defense Authorization Bill approved last
 ** week that covers DC-X (SSRT) Followon.  

Section 217, Single Stage Rocket Technology

(a) Program Funding -- the Secretary of Defense shall establish a Single Stage Rocket Technology program and shall provide funds for that program within funds available for the Advanced Research Projects Agency. That program shall be managed within the Office of the Undersecretary of Defense for Acquisition.

(b) Funding -- Of the amount appropriated pursuant to section 201 for Defense-wide activities, $79,880,000 shall be available for, and may be obligated only for, Single Stage Rocket Technology.


 ** This is the section of the report accompanying the House Defense
 ** Authorization Bill that covers DC-X Followon.  The report language is
 ** intended to clarify the intent of the bill.

 From The House of Representatives Committee on Armed Services
 Report on the FY '94 Defense Department  Authorization Bill, H.R. 2401
 H. Rpt. 103-200, 103rd Congress, 3rd Session; July 30th, 1993, pp. 172-173

Single Stage Rocket Technology

The budget request included $4.88 million for single stage rocket technology (SSRT), also known as single-stage-to-orbit (SSTO), within the Ballistic Missile Defense Office (BMDO) follow-on technologies program to complete the final testing in phase one of the program.

The United States spends over $30 billion each year on space programs. Yet, unlike many other commercial activities that have benefitted and achieved greater efficiencies from military research and development, U.S. commercial launch costs are at least twice -- and in some instances as much as ten times -- the costs of foreign competitors. Similarly, it takes the United States at least four times as long to provide launch services to any given user.

The Congress must remain skeptical and avoid fully embracing the sometimes overly optimistic claims regarding SSRT/SSTO technology. Yet, if the United States is to regain its international competitiveness in this critically important military and economic area, it must pursue promising enabling space launch technologies that have the potential of dramatic reductions in launch costs.

Accordingly, the committee recommends the following:

  • (1) Transitioning SSRT/SSTO from BMDO to a "Space Launch Technology" program element within the Advanced Research Projects Agency.
  • (2) Continuing with the current management team.
  • (3) Adding an additional $75 million to begin phase two of the program.
  • (4) Conducting an open competition among aerospace companies for phase two of the program.

    (5) Examining options for DOD, other government agencies/departments, and industry cost sharing opportunities.

    None of the additional funds recommended to be authorized may be obligated until the congressional defense committees have been provided with a phase two program plan outlining objectives and technical milestones and certifying that funding support has been established for fiscal years 1995 and 1996.

    ** End of report excerpt


    
     Henry Vanderbilt              "Reach low orbit and you're halfway to anywhere
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     Space Access Society                              - Robert A. Heinlein
     hvanderbilt@bix.com                    "You can't get there from here."
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