Supersonic laminar flow tests continue on NASA's F-15B

Called the Supersonic Boundary Layer Transition, Phase II, or SBLT-II, the experiment consists of flying a small test airfoil, or wing section, attached underneath the F-15B. This allows NASA and Aerion engineers to continue investigating the extent and robustness of natural laminar flow over the test section at supersonic speeds.

Conducting the experiment in actual supersonic flight conditions with the F-15B enables engineers to capture data in a real-world flight environment, allowing for more precise refining of supersonic natural laminar flow airfoil design.

"The objective of the flight series is to investigate the extent and robustness of smooth, or laminar, airflow over the specially-designed test airfoil," said Brett Pauer, NASA Dryden's deputy High Speed Project manager. "Then, researchers will work to better understand when imperfections in the airfoil's surface cause the air to transition from laminar to rough, turbulent flow. The greater the extent of laminar airflow over a wing, the less aerodynamic drag there is, which reduces fuel consumption," Pauer said.

It is believed that significant laminar flow has never been achieved on any production supersonic aircraft before, so this research and the data being collected from the SBLT-II test fixture may help provide some of the data that might enable the design of supersonic aircraft in the future that have wings that produce laminar flow at supersonic cruise conditions.

One of the goals of NASA's High Speed Project, which utilizes the F-15B and other high performance jets, is reducing the fuel consumption and efficiency of future supersonic aircraft.

Project flights of the SBLT-II experiment began on the F-15B earlier this year. So far, four data-gathering flights have been flown, with six more planned.