Solid-Fuel Rocket Engine Industrial Base in Danger, Navy Official Says
The Navy is on track with plans to replace its Ohio-class submarines and extend the lives of its Trident D5 missiles, but a weakened solid-fuel rocket motor industrial base threatens to drive up costs for the latter program, the head of the service’s nuclear program said June 13.
There is declining demand from the Air Force and NASA for rockets fueled by solid propellants, said Vice Adm. Terry Benedict, director of the Navy’s strategic systems programs. The Navy maintains a continuous production capability of 12 motors per year — the minimum sustaining rate — but it cannot bear the full weight of sustaining the industrial base.
“If NASA decides to use liquid propulsion systems for their advanced booster, it will result in significant future cost increases for the Navy’s D5 and the Air Force’s [intercontinental ballistic missile] rocket loaders, but it will also result in diminished critical skills in the solid rocket motor industry production lines that I believe puts the entire specialized industry at risk,” he said during an Air Force Association breakfast speech near Capitol Hill.
“These increased cost and reduced critical skills in an already fragile industry will have an impact on the Navy’s Trident D5 program, a program that we have structured to have little or no allowance in schedule,” he said.
NASA is expected to make a decision sometime in 2016 on whether it will continue using solid propellants or switch to liquid, Benedict said. Until then, the Navy is working with the Air Force, NASA and the industrial base to find alternate solid fuels. Liquids are not an option for the submarine force because of safety concerns.
Solid fuels are stable and easy to maintain, but a solid-propelled engine cannot shut down once ignited and is less efficient, according to information on NASA’s website. It will continue burning fuel until there is nothing left, whereas liquid-propelled engines can be turned on and off as required.
The Navy currently is uses a specialized 1.1 class solid propellant, but the Air Force and it are looking at commercial 1.3 class propellants, Benedict said. The hope is that fuel could be bought in bulk to save cost and blended to make different formulations that would meet the needs of both services, he said. That search is “giving us some pretty positive returns,” he said.
Switching propellants could impact more than just cost, he added.
“Any change in propellants is going to affect the missile design. It’s an integral part of the missile design parameters,” he said. “We have a very clear reason to be into higher energetic propellants,” because the launch space inside of a missile tube is constrained.
The Navy is progressing with its life extension to the Trident missiles, which will keep the weapon in operation past 2040. Rather than develop a new missile, the service plans to replace aging parts and address obsolescence in the guidance system and electronic components, Benedict said.
“As we develop these components, we are using flight tests as well as some extremely innovative new testing methods to prove they are safe and effective for operation,” he said.
The service successfully demonstrated the Trident’s life-extended flight control and electronics package June 2 during a demonstration and shakedown operation, Benedict said. Two missiles were launched from USS West Virginia in the Atlantic, according to a Navy press release.
The demonstration marked the 149th and 150th successful test flight of the Trident. Lockheed Martin is the prime contractor for the missile and the life extension effort.
Construction of the first Ohio-class replacement submarine is scheduled to begin in 2021, but the Navy is already working on several systems that will be incorporated into the vessel.
For instance, it is developing the common missile compartment and strategic weapon system, both of which will be integrated on the Ohio replacement and the United Kingdom's newest nuclear submarine.
The service plans to test their designs, interfaces and performance before bringing them onboard the new submarines, he said. “We’ll do this [in advance] rather than doing all of this in the yard, and it will mitigate risk. It will also allow us to detect and correct any problems we observe.”