Arnold workers test new bomb with new jet

  • Published
  • By Philip Lorenz III
  • AEDC/PA
ARNOLD AIR FORCE BASE, Tenn. --  One new warfighter favorite joined forces with a near-future warfighting staple for the first time during testing ending in December at the U.S. Air Force's Arnold Engineering Development Center (AEDC) at Arnold Air Force Base, Tenn.

A team from Lockheed Martin and Arnold conducted simulated store separation testing on the Small Diameter Bomb (SDB) from the F-35 Lightning II in the center's four-foot transonic wind tunnel.

The F-35 JSF is a multi-service, multi-national aircraft program. Variants of the aircraft will be used by the U.S. Air Force, Navy and Marines. Partners in the JSF program's system and development phase include Italy, the Netherlands, Turkey, Australia, Norway, Denmark and Canada. Israel and Singapore will also have the opportunity to purchase the F-35. 

The primary focus of the initial phase of the recent testing at AEDC was to assess the SDB and how it interacts with this aircraft.

"In this particular test, the main objective was to look at the SDB.  It was a priority because it was a store that we had never tested before with this platform," said Monique Purdon, Lockheed Martin's wind-tunnel lead on the F-35 Lightning II store separation team. "The data being collected with both the captive trajectory system (CTS) and the Automated Model Attitude Positioning System (AMAPS) will feed into our aerodynamic databases to generate high-fidelity models for both flight clearance and stores certification."

Purdon said the aircraft model, at one-fifteenth scale, represents the U.S. Air Force's Conventional Take-off and Landing (CTOL) version of the F-35. The data from testing the SDB as a stand alone entry and information from the other stores will go into databases to help build-up more accurate simulation models, which will be validated through flight testing.

1st Lt. David Cancel, Air Force project test manager with the 716th test squadron at AEDC, said the store separation testing on the F-35 CTOL aircraft is critical to accomplishing the Air Force's mission.

"Each one of these aircraft variants has differences that need to be taken into account at the time of releasing a weapon," he said. "The purpose of the CTS testing was to simulate store separation to determine if the weapons will hit their targets. We also need to make sure that when we release that weapon it will not hit the aircraft causing damage that would be expensive in terms of material, labor, not accomplishing the mission, or worse, endangering the life of the Airman in the cockpit."

Purdon said the store separation testing has covered a lot of territory and agrees with Lieutenant Cancel that even seemingly small configuration variations are important to study and assess.

"We looked at several things during the test," she said. "Not only were we obtaining trajectories to examine the behavior of the SDB, we were also looking at configuration effects on the aircraft, such as whether the adjacent doors are open or closed. These types of aerodynamic factors can change the flow field around the aircraft and ultimately affect a store's motion during release."

Lieutenant Cancel said the AMAPS portion of the test was used to measure the airflow of the aircraft with stores attached to either or both wing stations and internal weapons bay stations.

"That way we can simulate how the aircraft will behave while it's flying," he said.

Purdon said that all stores separation testing provides unique opportunities and the SDB portion of the test was no exception.

"The biggest challenge with this particular test was the fact that compatibility between the F-35 and the smaller and lighter SDB was unknown, from a separation standpoint," Purdon said. "The trajectory behavior of the SDB differs from that of stores that have been around for decades. Furthermore, the aerodynamic forces can depend on the release configuration from the SDB's unique multi-carriage system, which increases the test complexity."

She said another challenge, besides capturing the data from the SDB portion of the testing, was planning their team's tasks to maximize the success of this phase of the testing and minimize the time required to complete it. Lockheed Martin's decision to conduct the store separation testing at AEDC was based on precedence and solid professional collaboration.

"There are other facilities that have the ability to do store separation testing," she said, "but we come here because of AEDC's technical expertise and the strong working relationship we have developed through previous testing."