The US Air Force (USAF) has conducted store separation tests on a 1/15th scale model of an F-35 Lightning II Joint Strike Fighter.

Tests were conducted in the Arnold Engineering Development Complex (AEDC) 4ft transonic wind tunnel (4T) at Arnold Air Force Base (AFB), reports Deidre Moon of AEDC.

It saw the return of the independent drive system (IDS) to service in the AEDC Propulsion Wind Tunnel Facility. This saved significant amount of funds, avoiding the need to use the Plenum Evacuation System (PES) for the test.

US Air Force test project manager Jimmy Williams said: “Captive loads and aerodynamic store separation testing was conducted and provided important data to the Joint Program Office, Air Force Seek Eagle Office and Naval Air Systems Command to better define the release envelope of a critical store from the F-35 Joint Strike Fighter.”

When running for Mach numbers below 1.3, IDS mode is preferred while testing for Mach above 1.3 PES process is favoured.

The model was store tested with GBU-54/38 Laser Joint Direct Attack Munition (JDAM) and air intercept missiles AIM-120 and AIM9-X.

Testing was carried out in two phases. Aerodynamic effects, or carriage loads, was the first phase of testing.

The process included attaching stores to one or both wing stations. Internal weapons bay stations were arranged to capture the carried stores’ impact during testing.

The AEDC-developed Automated Model Positioning System, which is controlled using a computer, was used to automatically pitch the model to appropriate altitudes.

Free stream and store separation were tested as part of the second phase. These tests were conducted at 4T using the Captive Trajectory and Grid Survey.

Williams added: “Our goal was to collect aerodynamic data used to determine characteristics of the GBU-54/38 Laser JDAM metric store for all three variants of the F-35.”

The fighter aircraft comes in three variants, namely F-35A, F-35B and F-35C.