General Atomics-Aeronautical Systems Inc. (GA-ASI) has announced that it completed the fourth and most recent wind tunnel test campaign for its proposal for the U.S. Navy’s MQ-25 unmanned carrier-capable inflight refueler. The tests were undertaken in a low-speed tunnel to assess the characteristics of the air vehicle’s high-lift and DLC (direct lift control) systems, the latter based on over-wing spoiler surfaces. Most importantly, the tunnel tests verified predictions based on CFD (computational fluid dynamics) data, and reinforce the design’s characteristics during carrier launches, recoveries, wave-offs, and bolters.
“The wind tunnel testing helps us to accurately predict the aircraft’s suitability for carrier operations,” said David R. Alexander, president, Aircraft Systems, GA-ASI. “The test results allow us to verify the aerodynamic characteristics of the Unmanned Aerial Vehicle. These tests are critical to the validation of the system’s ‘up and away’ mission performance and will subsequently lower technical performance risk for the Navy customer.”
In an earlier campaign, the MQ-25 design had been tested at NASA Ames in an 11-foot transonic tunnel, with the aim of verifying the air vehicle’s predicted mission performance. Further tunnel tests would be conducted during the upcoming EMD (engineering and manufacturing development) phase if GA-ASI is selected. They will include trials of engine inlet and exhaust flows, and also ice-shape tests to accurately predict performance in icing conditions. The conclusion of tunnel-testing is expected to be a trial to assess the safe high-speed separation of external stores such as the Aerial Refueling Store and fuel tank.
GA-ASI has also recently completed performance testing of a key element of its MQ-25 proposal. The component in question is the Hold Down Damper (HDD) for the aircraft’s arrester hook, which has been produced by GKN Aerospace’s Fokker division in Helmond, Netherlands.
During the trials, a range of dynamic conditions were simulated to evaluate the performance characteristics of the HDD, including damping, spring rate and pressure-control functionality. The results from the test provided validation of the computer-based modeling tool that has been employed to complete the design of the HDD, and which provides a quick-reaction capability for amendments.
The model has already verified that the GA-ASI HDD design meets Navy requirements for initial bounce, upswing and rebound, and bolter performance across a range of operational temperatures. It has also validated the construction and manufacturing processes that are planned for production. Overall, computer-based modeling tools permit a reduction in the development schedule and reduce costs during EMD.