Flying Qualities Parameter Identification using Short Duration Flight Test Inputs

An important outcome of flying qualities flight testing is the assurance of safe aircraft operation within its operational flight envelope. Modern test techniques typically require several minutes of data at a given flight condition using frequency sweep, chirp, or other long duration inputs from which critical flying qualities parameters can then be estimated. To dramatically reduce this time to five seconds or less, Systems Technology, Inc. (STI) is investigating the use of innovative parameter identification techniques that have been shown to work best with simple pulse-like inputs that are easily generated in a flight test environment. The techniques can be used to generate frequency responses from which flying qualities parameters can then be determined. In this paper the new Narrowband Signature frequency domain identification technique recently developed at STI is described. The technique is then applied to a limited set of flight test data generated with the Calspan Learjet 25 in-flight simulator. Results, including representative flying qualities parameters, are compared with the known aircraft "truth model."