How do you simulate challenging, stormy seas when testing a new weapon system? Naval Surface Warfare Center Dahlgren Division (NSWCDD) engineers found an effective solution in a less-than-obvious piece of technology – a motion base designed for flight simulators and theme park rides.
“The idea is to try to simulate these low-frequency, large-displacement and large-rotation environments,” said Test and Evaluation (T&E) Division Instrumentation Engineer Dr. Bryan Joyce. “Because of the payload requirements, the amount of motion we have to simulate and the fact that we have to do it in six degrees of freedom at once, we had to get a little creative to see how we could do this within budget and schedule.”
Joyce and his team acquired a motion base made up of six 5-foot-stroke actuators that all move independently. The actuators work together to produce motion in six degrees of freedom simultaneously on payloads weighing up to 30,000 pounds.
The team then adapted the motion base by designing a frame and platform that allows them to mount a weapon system of interest on the motion base. Inputting observed sea state data with hazardous conditions of up to 40-foot waves, the motion base simulates complex dynamic motions and allows engineers to observe how a capability or system might function on a ship that is underway.
According to T&E Division Senior Structural Dynamist Shawn Schneider, the benefits of testing systems in a true-to-life environment before sending them to the fleet are vast.
“With lab-based tests we can simulate the worst environments at will and we can simulate them repeatedly,” Schneider said. “The weapon systems in these performance tests are usually in the development process so we’re still changing components and tuning control systems. So letting these guys see the exact same environment repeatedly helps them to make tunes and tweaks and see how it affects performance.”
In the repeatable test environments, the motion base simulates, engineers can assess things such as system’s ability to effectively track targets while at sea. Additionally, these test environments can determine if a harsh environment, such as tempest seas, will cause components to fail or become misaligned and a hazard to surrounding sailors or ship equipment.
“The ability to perform these tests in a closed scenario, inside of a lab where we can put up safety precautions and limit exposure is absolutely paramount,” Schneider continued.
The adapted motion base is currently installed at Army Test and Evaluation Command, Redstone Test Center in Huntsville, Alabama.
Dr. Luke Martin, Technical Expert for shock and vibration in the T&E Division, noted that the continued collaboration between NSWCDD and their Army counterparts in recent years was instrumental in the success of the project.
“We’ve been on the phone with them once or twice a week through the past five or six years,” Martin said. “We are always looking at the warfighter’s needs and how to best meet the warfighter’s needs. We really work seamlessly together almost like sister organizations even though we are Army and Navy.”