DC-X is a low-speed flight regime testbed for a proposed reusable rocket- powered Single Stage To Orbit 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 both rapid turnaround of a reusable rocket by a minimal ground support crew, and rapid low-cost development of an advanced aerospace X-vehicle type engineering testbed by a small highly-motivated engineering team.
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.
As of Friday, June 18th, DC-X was through with its ground-test program, after a total of nine test-stand engine firings since May 20th. Starting Monday June 21st, the DC-X crew began moving the operation up the road to the White Sands Missile Range, where they're expected to begin flight testing toward the end of July.
The week since our last report saw two final test-stand runs, both "quilt" tests, patchwork combinations of various simulated flight regimes, designed to fill in the remaining gaps in vehicle ground test data.
On Tuesday, June 15th, the engines were fired for 40 seconds before ground test software shut them down for an out-of limits condition caused by an extreme combination of control inputs. Peak throttle setting was 95%. According to a knowledgable source, the shutdown would not have occurred if the vehicle had actually been flying, and indeed none of the test stand aborts seen to date would have stopped an actual flight -- all have been "ground-induced anomalies".
Presumably this means they were anomalies either caused by static test-stand conditions -- lack of flight airflow around the vehicle, lack of actual acceleration, different vibration environment, and so forth -- or anomalies caused by ground-commanded control inputs or ground-test safety limits that would not be present in flight.
The final ground test firing took place on Thursday, June 17th, and went according to plan, lasting 64 seconds and reaching 100% throttle settings.
With the end of ground testing, the DC-X program has accomplished a significant portion of its overall goals. The nine firings included tests that simulated all phases of takeoff, hover, translational flight and landing for the first flight test series. Key portions of the vehicle control software for nose-first to tail-first rotation maneuvers were also tested.
Significantly, all these tests were run by a three-person crew in the DC-X Flight Ops Control Center trailer. A major goal of the DC-X program is proving that it doesn't take a standing army to build or fly a rocket. Both look pretty close to proven.
Demonstrating fast turnaround between flights is also a major DC-X objective. May 26th's eight-hour fire/defuel/service/refuel/fire cycle time goes a long way toward that goal too.
"We were pleased with the vehicle's performance as well as the ease with which we can turn it around between tests. We're realizing the benefits that come from designing the system to be totally reusable." -- Pete Conrad, DC-X flight manager.
"The entire DC-X system, including avionics, software, hydraulics, propellant feed systems, engines, and sub-systems met or exceeded our expectations. Through this rigorous series of tests we learned how to efficiently service the vehicle and quickly load and unload propellant. We acquired extensive data showing that the vehicle's operations, support and maintenance features will help us to achieve our goal of aircraft-like operations." -- Paul Klevatt, DC-X program manager.
First official DC-X flight (there will be short "bunny hop" stability tests done beforehand) currently looks like happening in late July.
There's been a flurry of DC-X pieces in the regular press lately. A list follows:
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, variously known as DC-X2 and SX-2 (Space Experimental 2). This could end up as a suborbital vehicle powered by 8 RL-10-a5 engines, capable of reaching mach 6 and 100 miles altitude, built with orbital-weight tanks and structure and 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. The money would come out of the $3.8 billion BMDO budget already pretty much agreed on for the coming year. 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 likely be on the order of several hundred million.
SX-2 would start out under BMDO (formerly SDIO), so support from members of the House and Senate Armed Services Committees (HASC and SASC) is vital. The actual name they know SX-2 by is "followon funding for BMDO's SSRT (Single Stage Rocket Technology) program." The specific action we're calling for is for Congress to "fence off" $75 million in BMDO funding for this project next year -- we are not asking for any new funding authority.
Lining up support in the House has gone well; all the key committee leaders are at least aware of DC-X Followon, and most seem to be favorably disposed. Representatives Ron Dellums (D, CA, House Armed Services Committee Chair) and Pat Schroeder (D, CO, HASC Research & Technology Subcommittee Chair) could still use some encouragement.
Schroeder's subcommittee "marks up" the FY' 94 Defense authorization this week of June 21st. It's late, but better than never for calls and faxes in support of fencing off $75 million of BMDO funds for an SSRT followon.
Schroeder phone 202 225-4431, fax 202 225-5842, 2208 RHOB, Washington DC 20515 Dellums's full HASC "marks up" the Defense authorization bill next week, starting June 28th. Calls, faxes, and letters to Dellums are still helpful. Dellums phone 202 225-2661, fax 202 225-9817, 2136 RHOB, Washington DC 20515
Keep phone calls brief, polite, and to the point - tell whoever answers that you're calling to let them know you support fencing off $75 million in BMDO funding for a followon to BMDO's Single Stage Rocket Technology ("SSRT") program. If you feel like it, throw in your favorite reason why this would be a good thing. If the person who answers wants to know more, answer their questions as best you can, otherwise thank them and ring off.
Letters too should should be brief, polite, and to the point, though you can go into a bit more detail as to why a DC-X followon is the neatest thing since sliced bread and good for the country too. Keep it under a page and state your basic point at the start.
Don't overdo it, but in general try to know who you're contacting and emphasize benefits likely to appeal to them.
The main effort should begin to shift to the Senate over the next few weeks, specifically to the analagous Senate Armed Service Committee leaders and members. Senators to contact are:
-- Senator James Exon (D, NE), Chairman of the SASC Subcommittee on Nuclear
Deterrence, Arms Control, & Defense Intelligence ("Nuke" Subcommittee)
- phone 202 224-4224, fax 202 224-5213, US Senate SH528, Washington DC 20510.
-- Senator Jeff Bingaman (D, NM), Chairman of the SASC Subcommittee on
Defense Technology, Acquisition, & Industrial Base ("DT" Subcommittee).
- phone 202 224-5521, fax 202 224-1810, US Senate SH524, Washington DC 20510.
-- Senator Daniel Inouye (D, HI), Chairman of the Senate Appropriations
Committee's Defense Subcommittee ("Def").
- phone 202 224-3934, fax 202 224-6747, US Senate SH722, Washington DC 20510.
Contacting these Senators' Republican counterparts would also be useful. These are:
-- Senator Trent Lott (R, MS), ranking Republican member of "Nuke". - phone 202 224-6253, fax 202 224-2262, US Senate SR487, Washington DC 20510. -- Senator Bob Smith (R, NH), ranking Republican member of "DT". - phone 202 224-2841, fax 202 224-1353, US Senate SD332, Washington DC 20510. (apologies to Senator Liebermann, CT - we incorrectly listed him as RRM of this subcommittee last week. Senator Liebermann is in fact a Democrat. He is on SASC, however, so contacting him won't have been wasted.) -- Senator Ted Stevens (R, AK), ranking Republican member of "Def" - phone 202 224-3004, fax 202 224-2354, US Senate SH522, Washington DC 20510. Henry Vanderbilt "Reach low orbit and you're halfway to anywhere Executive Director, in the Solar System." Space Access Society - Robert A. Heinlein hvanderbilt@bix.com "You can't get there from here." 602 431-9283 voice/fax - Anonymous -- Permission granted to redistribute the full and unaltered text of this -- piece, including the copyright and this notice. All other rights -- reserved. In other words, intact crossposting is strongly encouraged.