The NTPS “loads” Impala (S/N 155TP) was recently upgraded to include structural dynamic exciter motors.
The motors were installed in support of the Structural Loads and Flutter module (T&E 4205). With their addition, the school is now able to show students the dynamic response of the aircraft while in flight, and allows them to compare model estimates, with ground vibration tests (GVT), and in-flight responses.
Impala 155 was modified by installing two electrically driven motors – one on each wing. Each motor drives an asymmetric weight which generates load pulses at set frequencies. The motors are controlled from the rear seat of the Impala which allows the flight tester to sweep through a range of frequencies and to dwell on frequencies of interest.
After the Impala was modified, PACS Engineering conducted a complete GVT which identified and characterized six structural response modes. The aircraft was then flown by the schools staff to clear a safe envelope and to survey the GVT modes while in flight.
The excitation system performed flawlessly and the modes were demonstrated. This new capability will be added to the course curriculum in May.