On 10 May 1995, McDonnell Douglas announced plans to develop the Delta III, a next generation expendable launch vehicle. [(1)] Building on the success of the Delta II, McDonnell Douglas planned to develop this new intermediate-class rocket with its own funds. The Delta III would be designed and developed at the McDonnell Douglas Aerospace (MDA) facilities in Huntington Beach, California. The final assembly of the Delta III would take place in Pueblo, Colorado, with final checkout and launch at Cape Canaveral Air Station, Florida.
The payload capacity of the new Delta III was expected to be be 8,400 pounds to geosynchronous transfer orbit, more than double the capability of the existing Delta II. The new intermediate-lift rocket would be capable of launching Hughes' largest satellite model, the three-ton, body-stabilized HS 601.
The most significant changes in Delta III's evolution from the existing Delta II were a new single-engine, cryogenically propelled upper stage and a larger fairing to house the payload. The cost to McDAC to do the upgrade was estimated at "more than $200 million." [(2)]
Major changes to the system included:
- A new cryogenic upper stage. With a number of details still uncertain as of 1995, although the company claimed to have a detailed design in hand. As of 1995, the engine had yet to be identified, with the company suggesting candidate engines from Aerojet, Rocketdyne and Pratt & Whitney. It was expected that the Centaur's RL-10 or derivative (which would seem to provide about the right performance) would be the likely choice. In general, the new cryogenic upper stage seemed to be the single largest area of risk in the program, particularly in light of the fact that every other cryogenic upper stage exhibited sognificant development problems. McDAC Program Director Rick Arvesen acknowledged that this would be the greatest hurdle for Delta III. [(3)] Thus it may be anticipated that McDAC will take a rather conservative design approach.
- An expanded 13.1 foot diameter fuel tank for the first stage (the LOX tank retains the existing 8 foot diameter). By growing the diameter of at least part of the core stage, the vehicle could accomodate more propellant, while keeping the existing length (which reduces controllability problems).
- New 13.1 diameter payload shroud.
- Upgraded solid fuel motors (46" diameter versus 40", 10 % longer), with three of the nine motors featuring thrust vector control (currently none of the SRMs have TVC). The need for TVC on the motors appeared to be driven by concerns that the existing core engine of the Delta II would not provide sufficient control authority for the new configuration. These would be provided either by Hercules or Thiokol, selected through a competitive procurement.
- New avionics and software, although the details had not been enumerated in published reports as of 1995. As with past Delta upgrades, the avionics system was expected to be modified to match the new configuration, with control system software and hardware modified to support the new solid fuel motors and vehicle configuration.
The initial customer for Delta III was Hughes Space and Communications International, a unit of Hughes Electronics Corporation, which was owned by General Motors Corporation. Hughes and McDonnell Douglas signed a contract for 10 firm launches, plus options for additional launches through 2005. The total value of the contract, depending on options exercised, could be up to $1.5 billion. With an anticipated first launch during the first half of 1998, and the tenth satellite in 2002, options could extend the launches to 2005.
The Delta III was a financial and public-relations disaster. On its maiden flight in 1998, the rocket had to be destroyed soon after launch when it strayed off course. On the next flight, the second stage did not work properly, resulting in an expensive satellite left in a useless orbit. The third Delta III carried a dummy payload. This launch was the last as of late 2002. No paying customer trusted the rocket enough to risk a real satellite.
1. Cfirstname.lastname@example.org (Reuters), email@example.com (Dick Buenneke), firstname.lastname@example.org (David Paul Huntsman), email@example.com (Jim Kingdon), firstname.lastname@example.org (Larrison), email@example.com (Marcus Lindroos INF), firstname.lastname@example.org (Alastair Mayer), email@example.com (Mark Oderman), "Delta-3," sci.space.policy, May 1995.
2. Wall Street Journal, 8 May 1995.
3. "Matching Delta II's Success May Be Tough for MDC's New Launcher," Space Business News, 17 May 1995, page 3
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