Cape Canaveral Fla. – United Launch Alliance (ULA) let its “biggest dog” off the leash on a classified mission last week. The Delta IV Heavy rocket thundered off of Cape Canaveral Air Force Station’s Space Launch Complex-37 (SLC-37) carrying a payload for the National Reconnaissance Office dubbed NROL-15 at 9:15 a.m. EDT. The primary contractor that builds the huge Delta IV Heavy is United Launch Alliance, the coalition of The Boeing Company and Lockheed-Martin. However, other highly-experienced contractors have also provided key material support.
Pratt & Whitney Rocketdyne, based out of Canoga Park, California provided three powerful RS-68A engines. This was the inaugural launch for this iteration of the RS-68A. Information provided in a Pratt & Whitney Rocketdyne press release describes the RS-68A as a liquid-hydrogen/liquid-oxygen booster engine designed to provide increased thrust and improved fuel efficiency to the Delta IV family of launch vehicles.
The RS-68A produces 702,000 lbs of thrust at liftoff – increasing to around 800,000 lbs of thrust as the launch vehicle enters the hard vacuum of space. This is nearly 39,000 lbs more thrust than the standard RS-68.
“What we saw with this launch was three RS-68As provide an evolutionary leap forward in terms of performance,” said Pratt & Whitney Rocketdyne’s Vice President of Launch Vehicle and Hypersonic Systems Steve Bouley. “Today was the first mission for this version of the RS-68 and although the RS-68A was designed for the Heavy the entire Delta IV family will be upgraded to use these engines.”
Like all rocket engines, the RS-68A went through exhaustive testing – during hot-fire tests the rocket operating for a cumulative run-time of 4,800 seconds which is more than 10 times what is required to power the Delta IV Heavy to orbit.
Developed in the 90s, the RS-68 was designed with the goal of producing a less-complex, more fuel efficient heavy-lift engine. More importantly, the engine was developed with private company funds for commercial use. The nozzles used on the RS-68 were produced by ATK who has contributed in other ways to the Delta IV rocket.
The nozzles are constructed from thermal protection material. This is sturdy stuff, capable of surviving the extreme temperatures generated during launch (temperatures can exceed 4,000 degrees Fahrenheit). ATK and Pratt & Whitney Rocketdyne have collaborated over the past seven years to design, develop and test the engine assembly.
ATK has further contributed to the recent launch by supplying thirteen composite structures for the Delta IV rocket. This included three thermal shields that protected the RS-68A engines during flight. ATK also provided three center body structures that connected the liquid oxygen and liquid hydrogen tanks as well as two medium and one heavy skirt that is on each of the three common booster cores (the Delta IV Heavy is in essence three of the same rockets combined into one). ATK’s composites were also used on the interstage of the center booster core, the nose cones of the two strap-on boosters, and one set structures that connect the upper stage liquid oxygen tank with the upper stage hydrogen tank.
These composite structures come in a variety of sizes ranging from four to five meters to eight meters long. ATK produces these elements using hand lay-up machining techniques designed to ensure quality.
The upper stage reaction control system’s propellant tank is also produced by ATK. They utilize an elastomeric diaphragm to dampen fluid motion that limits the shifting of the propellant’s center of gravity. The design has been proven on both the Delta and Atlas V family of launch vehicles – as well as on the space shuttle and such famous interplanetary missions as Pioneer, Voyager and Cassini.
“Today’s successful launch of the NROL-15 mission is the third of four launches for the NRO this year and the second EELV launch for the NRO in just nine days,” said Jim Sponnick, ULA vice president, Mission Operations in a ULA press release issued shortly after the launch. “We congratulate the combined NRO, U.S. Air Force and ULA team along with our mission partners for their continued focus on mission success as we deliver the critical capabilities to support the soldiers, sailors, airmen and Marines.”
In short, United Launch Alliance has coordinated with organizations that have years of experience in an incredibly wide-range highly-specialized fields. ULA constructed the primary sections of the Delta IV in Decatur, Ala. Besides Pratt & Whitney Rocketdyne’s RS-68A and ATK’s composite components the Delta IV also employs a single RL-10 liquid hydrogen engine that is built by Pratt & Whitney Rocketdyne.
The Delta IV family of rockets was developed as part of the Evolved Expendable Launch Vehicle Program. This program marked its 50th launch just nine days earlier from the nearby Space Launch Complex-41. This mission, also for the National Reconnaissance Office, launched atop one of ULA’s Atlas V rockets June 20th.
So with ULA producing the main components and Pratt & Whitney Rocketdyne and ATK producing other key elements the Delta IV was launched on its secret mission. The launch team worked through several technical issues that saw the launch time slip – but not scrub. This fact suggests that the team consisting of United Launch Alliance, Pratt & Whitney Rocketdyne and ATK, along with a number of sub-contractors have developed a powerful and reliable launch system. So much so that NASA has tapped the Delta IV Heavy to launch the uncrewed test article of the Orion spacecraft. Dubbed Exploration Flight Test 1 (EFT-1) this mission is set to take place in 2014. The rocket planned to launch Orion on a regular basis, NASA’s Space Launch System (SLS), is still being developed, therefore the Delta IV Heavy was tapped to fill in for the SLS for the EFT-1 mission. The Orion that will be used on EFT-1 arrived at KSC this week. With the successful launch of NROL-15,
Sponnick took a moment to acknowledge the team that helped power NROL-15, the same team working to do the same for the inaugural flight of Orion.
“The upgraded Delta IV Heavy vehicle was developed with an extremely thorough and comprehensive system engineering process by the ULA and Pratt-Whitney Rocketdyne teams, along with substantial involvement by our U.S. government customers,” Sponnick said. “Congratulations to the entire team on today’s successful inaugural flight of the upgraded Delta IV Heavy launch vehicle and the RS-68A engine.”