Status update of the AEDC wind tunnel Virtual Flight Testing development program

Abstract

Recent efforts at the Arnold Engineering Development Center (AEDC) have focused on the development and demonstration of a new wind tunnel test capability called Virtual Flight Testing (VFT). The new capability will provide aircraft and missile designers with a mechanism to evaluate and validate autopilot and flight vehicle control system designs in a wind tunnel environment. The airframe, including the autopilot, inertial sensors, and control actuators, can be suspended in the wind tunnel by a device which allows free rotation of the VFT hardware in response to moments produced by steady and unsteady aerodynamic interaction with the airframe and control devices. It is hoped that the VFT methodology can bridge the gap between hardware-in-the-loop testing, which is based on static wind tunnel testing, and open-air flight testing. If this is the case, then VFT can mitigate the risks of flight testing, reduce program development cycle time, and reduce the cost of testing by reducing the number of test sorties and the number of costly assets required for weapon system development. A demonstration of the viability of the VFT concept was successfully completed in FY01. Flight test hardware from the Navy BOA missile flight test program was modified and suspended by an eight-wire suspension system attached to a roll collar fitted around the missile. The flexibility of the suspension system provided unrestrained freedom of motion in pitch and roll, as well as some restrained yaw motion. The test, conducted in the High Velocity Air Flow System (HiVAS) at the Naval Air Warfare Center (NAWC), China Lake, California, demonstrated that the dynamic response of an aerodynamically unstable missile in ground test was similar to that experienced in flight both when released prior to autopilot initialization and when the autopilot was engaged prior to release. That is, the ground tests produced pitch, yaw, and roll rates similar to those observed in actual flight tests. The missile was easily controlled and followed its preprogrammed maneuvers after release, even when its translational motion was constrained by its support mechanism.