Tim Furniss/CAPE CANAVERAL
Boeing is preparing launch pad 17B at Cape Canaveral, Florida, for the first launch of the Delta III booster in June. The company is also expecting an Evolved Expendable Launch Vehicle (EELV) contract from the US Air Force in June to start development of the new Delta IV. With costs underwritten by the US Government, the Delta IV will enter the commercial market after 2000.
The Delta III will provide increased competition in the current commercial-launcher market and will be the former McDonnell Douglas' first heavyweight booster, capable of placing 3,810kg into geostationary transfer orbit (GTO), the main market for civilian commercial launches. This compares with the maximum 1,870kg GTO capability of the Delta II.
The Delta II has two civil GTO communications-satellite launches remaining, but is nonetheless the busiest booster, with 85 launches planned for various versions for the USAF, NASA and some commercial customers for low-Earth-orbit launches.
The Delta III has been booked for 18 GTO launches to 2002, including the Hughes Galaxy X. Twelve other Hughes satellites are manifested for GTO launches, plus five from Space Systems/Loral.
ROCKETDYNE ENGINES
The Delta III's first stage has a similar Rocketdyne RS-27A main engine to that used on the Delta II, and two Rocketdyne vernier engines for roll and attitude control. The diameter of the first-stage fuel tank at the top of the stage has been increased, providing the first element of a hammerhead-like upper structure of the vehicle.
First-stage thrust is augmented by nine new and larger Alliant Techsystems solid-propellant strap-on boosters, three of which are equipped with thrust-vector control systems for better vehicle manoeuvrability and control. The graphite-epoxy motors provide 25% more thrust than those used on the Delta II.
The major innovation on the Delta III is the second-stage cryogenic, liquid-oxygen/liquid-hydrogen Pratt & Whitney RLB10-2 engine derived from the dual engines used on the Centaur upper stage which flies on the Atlas and Titan 4 vehicles. On top of the second stage is the 3.99m-diameter payload fairing.
The Delta III incorporates the redundant inertial flight-control-assembly avionics system used on the Delta II. The system employs ring-laser gyros to provide redundant three-axis attitude and velocity data.
Modifications to Pad 17B (used for the Delta II) to accommodate the Delta III include new locations to service the vehicle and payloads, a new liquid-hydrogen storage tank, installation of acoustic ducts for sound suppression, a new water-suppression system, a new air-conditioning system for the Delta III interstage and a modification to the umbilical tower to prevent liquid-hydrogen entrapment. Pad 17A will be used solely for Delta II launches.
Meanwhile, Boeing has invested $250 million in preparations for its expected share of the $2 billion US EELV contract to be awarded in June. Two companies, Boeing and Lockheed Martin, are working on $60 million contracts for final design work, and it was originally planned to award one contract to one company. Now, the USAF plans a double-source strategy which it hopes will strengthen the US space-launch industry, encourage greater investment and decrease the Air Force's costs.
Boeing will start work to rebuild the old Saturn 1 launch pad 37 at Cape Canaveral for launches of the Delta IV EELV. The pad is now basically just a concrete launch stand.The SLC-6 pad at Vandenberg AFB, California, is also being refurbished for Delta IV launches for $120 million, Boeing says.
It wants to be able to reduce on-pad work time to six days from the 24 days for the Delta II. A major goal of the EELV programme is to reduce launch costs by 50%, or $5,500 per kilogramme of payload into orbit. Boeing obviously sees a commercial role for the Delta IV, which was proposed originally as a three-vehicle fleet for the sole EELV contract to meet small, medium- and heavy-launch requirements. GTO capabilities will be 2,180kg, 4,535kg and 14,960kg, respectively.
The Delta IV Small consists of a Common Booster Core (CBC) stage using the first US-developed cryogenic first-stage engine since the Space Shuttle main engine. This is powered by a new Rocketdyne RS-68 engine with a simplified gas-generator cycle system. The vehicle's second stage would use a Delta II third- stage engine and fairing.
DELTA IV STAGE
The Delta IV Medium will consist of the CBC stage, the Delta III cryogenic second stage and Delta III fairing, while the Delta IV Heavy will uses three CBCs strapped together, a modified Delta III second stage and new fairing from the Titan IV programme. Given Lockheed Martin's experience with heavyweight launchers, it seems logical to assume that the Delta IV may take the small, and some of the medium, lift role.
Other investments by Boeing in preparation for the Delta IV will be $25 million in additional equipment at the company's Delta engineering and fabrication plant at Huntington Beach, California. The company is completing a new Delta IV manufacturing plant in Decatur, Alabama to build the CBC stage, which will employ about 3,000 staff. The second-stage and upper-stage assembly work will be at Boeing's Delta II plant at Pueblo, Colorado.
Source: Flight International
