MOUNTAIN VIEW, Calif. --
The team at Arnold Engineering Development Complex’s National Full-Scale Aerodynamics Complex, or NFAC, recently added rain simulation to the organization’s portfolio of capabilities.
The F-16 System Program Office has been trying to address an issue with rain pooling on the canopy of the aircraft and reducing pilot visibility. Pilots try to avoid flying through inclement weather, but pop-up storms present an unavoidable risk. Because pilots avoid such flying conditions, field testing provides limited opportunities to gather data on proposed solutions.
NFAC provided the means to test multiple potential solutions against a baseline in a safe, controlled and replicable environment.
“The NFAC team was tasked with simulating flight conditions for the F-16 (Fighting Falcon) approach, landing and roll-out, and various rain intensities in the facility’s 40-foot by 80-foot test section,” said Chris Nykamp, test engineering supervisor.
Water was sprayed onto the test article and then visibility was assessed using a camera showing the pilot’s perspective to view light rails that simulated runway landing lights.
“Spraying water into the wind tunnel circuit during operations was a task that had never been previously attempted at the facility,” Nykamp said. “The NFAC engineers were tasked with designing and installing a remotely operated rain system to distribute the water onto the canopy for a wide range of airspeeds and rain intensities.”
After the water was introduced into the wind tunnel circuit, it also had to be diverted and collected to prevent harming team members, the facility or the environment. Derick Daniel, with the AEDC Modeling and Simulation Group, used computational fluid dynamics to predict how much water and where it would go under the various test conditions to assist the NFAC team in developing a plan to remove it from the circuit.
The NFAC team was also assisted by F-16 pilots who made the trip to NFAC to observe the testing and offer input and guidance.
“Overall, the feedback from the customer and the F-16 pilots was very positive on the test team’s ability to recreate the visibility issue and demonstrate relative performance from each of the candidate fixes,” Nykamp said.
“In research and development it is rare for us to be able to work closely with the end user. In this case, working directly with the F-16 pilots intensified the importance of our mission. Ultimately the data collected on this test will help ensure the safety of these men and women.”