Heavy lifting for the new millennium
by Anthony Young
|The Delta’s launch manifest evaporated when the shuttle came online and after 24 years, Delta production ceased. The Delta did not die, however; it merely went through a period of arrested development.|
It was around this time that McDonnell Douglas (the two aircraft companies merged in 1967) won the Air Force contract for up to 20 launch vehicles needed for the Navstar Global Positioning System (GPS). The original Delta was extended more than 3.5 meters with larger fuel tanks, and a new larger diameter payload fairing. The first Delta 2 was successfully launched on February 14, 1989, deploying the first group of GPS satellites in proper orbit. McDonnell Douglas wasted no time reviving its commercial satellite launch services with the Delta 2, and it has remained in production—with the inevitable performance upgrades—ever since. In the 1990s, Boeing purchased McDonnell Douglas and with it the entire Delta infrastructure. Boeing then developed the Delta 3 to fulfill growing commercial satellite size and weight. This derivation was not successful however, with only one out of three launches successful. Delta had to grow yet again.
In the mid-1990s, the U.S. Air Force initiated the Evolved Expendable Launch Vehicle (EELV) program. The mission statement for the EELV program was, “Partner with industry to develop a national launch capability that satisfies both government and commercial payload requirements and reduces the cost of space launch by at least 25 percent.” In broader terms, it was also meant to maintain or improve the reliability, operability and capability of then-current medium through heavy lift launchers that included the Delta, Atlas, Titan 2 and Titan 4. It is interesting to note the Air Force saw the need to consider the commercial aspects of the launch vehicle in the mission statement.
|“You don’t get the chance to basically have a clean slate and say ‘OK, take all the experience of the space programs of the past and go do it the way you want to and address all those issues,’” said Boeing’s Collins.|
The Air Force issued its EELV request for proposals in May 1995. Boeing looked at all the requirements, including lift capability, and concluded the existing Delta 2 could not achieve the stated goals. A larger and more powerful launch vehicle would be needed. Boeing’s chief competitor, Lockheed Martin, pursued ways of upgrading its Atlas launch vehicle. To achieve the cost reduction goals, Boeing reviewed every phase of manufacturing, use of existing hardware, delivery of the new Delta to the launch facility, even the means of delivering the launch vehicle to the pad. Boeing gave the Delta management and engineering teams a unique opportunity of designing a brand new launch vehicle, to do it better and cheaper than before.
Dan Collins is Boeing’s Delta program manager. In November of 2002, he related to Spaceflight Now just what it meant for all involved. “You don’t get the chance to basically have a clean slate and say ‘OK, take all the experience of the space programs of the past and go do it the way you want to and address all those issues. There is a challenge to it but you also realize you are in a once in a lifetime position with new engines, new factories, new launch pads. You know, this hasn’t happened since the 60s. We were given by The Boeing Company an opportunity that will not happen again in our careers and I think folks are realizing that as we are getting through the day to day hassles and challenges. This is neat stuff.”
The new Delta 4 uses a 5-meter (16 feet) diameter Common Booster Core (CBC) measuring 150-feet in length. This CBC is powered by an all-new liquid hydrogen and liquid oxygen engine, the RS-68. The second stage consists of the four-meter diameter upper stage developed for the Delta 3 powered by the Pratt & Whitney RL10B-2 engine. Next in the Delta 4 family includes the addition of two strap-on solid rocket motors. The third derivation of the Delta 4 includes a five-meter diameter second stage with larger fuel tanks and two SRMs on the CBC; the fourth derivation differs by having four SRMs strapped to the CBC. Finally, the Delta 4 Heavy consists of three CBCs with the five-meter diameter second stage.
Powering the Delta 4 CBC is the first new large rocket engine in more than 25 years, the last being the Space Shuttle Main Engine (SSME). Appropriately, Boeing’s Rocketdyne division was given the challenging task of designing the engine to meet lowest possible cost, reduced complexity and number of parts, simplified manufacturing, high thrust to weight ratio and other variables. Powered by liquid hydrogen and oxygen, the target of generating more than 2.9 million newtons of thrust was achieved, producing 12,700 megawatts. The RS-68 engine program achieved something just as important for the United States. It restored America’s technological capability in the design and manufacturing of leading-edge high performance rocket engines. The engines are assembled and tested at upgraded facilities at NASA’s John C. Stennis Space Center in Mississippi.
“What we have accomplished with the RS-68 is nothing less than the emergence of a new generation of American rocket engine designers and builders,” said Byron Wood, vice president and general manager of the Rocketdyne Propulsion & Power division of Boeing. “A torch has been passed from the team that powered us to the Moon and built the Space Shuttle Main Engine to a new generation using new tools and techniques.”
Boeing built an entirely new infrastructure around the Delta 4, from the first steps in manufacturing to complete checkout and finally, launch. This now includes a new, state-of-the-art 140,000-square-meter facility in Decatur, Alabama that dramatically reduces the manufacturing cost of the Delta. Boeing also built a new launch complex and horizontal payload integration facility at Cape Canaveral Air Force Station near the Delta 2 complex in Florida and duplicated the facilities at Vandenberg Air Force Base in California.
|“What we have accomplished with the RS-68 is nothing less than the emergence of a new generation of American rocket engine designers and builders,” said Rocketdyne’s Byron Wood.|
The first Delta 4 was launched from CCAFS on November 20, 2002 and successfully placed the Eutelsat W5 satellite into geosynchronous orbit. The next successful launch of the Delta 4 took place March 10, 2003 and the latest was on August 29th. Fall of 2003 was a busy one for Team Delta as they worked to assemble the three CBCs of the Delta 4 Heavy in the Horitzontal Integration Facility at the Cape. The launch vehicle was loaded onto its Elevating Platform Transporter in December. On December 10, the Delta 4 Heavy was transported to SLC 37, pad B. Once there, it took a mere 20 minutes for the Fixed Pad Erector to elevate the large rocket to its vertical and locked position on the launch table.
All this activity was of utmost interest to a team from NASA that visited Boeing’s Delta 4 operations at the Cape in December. This included Dennis Smith, NASA manager of the Orbital Space Plane; Bob Hughes, NASA chief engineer for the CEV, and Greg Hite, NASA manager for crew survival and escape. They were there to evaluate the Delta 4 Heavy both for the OSP and the yet to be announced CEV. All eyes were on this rocket as a future manned launch vehicle.
The last U.S. man-rated expendable launch vehicle was the Saturn 1B. To support the Sklyab and Apollo-Soyuz Test Project programs, one of the Saturn V Launch Umbilical Towers was modified with the addition of a “milkstool”, as it was called, to launch the Saturn I-B for each three-man crew. The last manned Saturn 1B was launched July 15, 1975 with Thomas P. Stafford, Vance Brand and Donald “Deke” Slayton to rendezvous with the Soyuz spacecraft in orbit. The United States has not had a man-rated ELV in more than a quarter of a century.
With the new space exploration initiative announced by President Bush requiring the phase-out of the space shuttle, NASA immediately began looking at launch vehicle options. The Boeing Delta 4 Heavy was a prime contender. How does it compare to the old Saturn 1B? The Delta 4 Heavy will be taller at 71.6 meters compared to the Saturn 1B at 68.5 meters. The Saturn 1B first stage generated 7.3 million newtons of thrust at liftoff; the Delta 4 Heavy will generate 2.94 million newtons from each of its three RS-68 engines for a total of 8.82 million newtons of thrust at liftoff. The Saturn’s second stage J2 engine generated 1.03 million newtons of thrust. The Delta 4 Heavy’s second stage is powered by a Pratt & Whitney RL10B-2 with 110,000 newtons of thrust, but with a specific impulse of 465.5 seconds. For the Delta 4 Heavy, the bottom line is its ability to place 23,000 kilograms into low Earth orbit, and 13,100 kg into geosynchronous transfer orbit.
The launch of the Delta 4 Heavy in July will mark a new milestone in America’s illustrious history of ELVs and may very well power the next generation of manned exploration vehicles.