Abstract:
A programme of research has now been completed in the College of
Aeronautics (CoA) at Cranfield University to investigate the use of a
Modified Stepwise Regression (MSR) procedure. The technique was
applied to data obtained from a small BAe Hawk aircraft model flown in
a dynamic wind tunnel facility in order to try to estimate the
aerodynamic stability and control derivatives of the model.
A variety of preliminary experiments were performed to enable the
static stability of the Hawk model to be evaluated and estimates for a
limited number of aerodynamic derivatives were obtained. The initial
experiments also allowed data acquisition and processing systems to be
developed. Experience of flying and controlling the model in the wind
tunnel was gained.
The MSR technique was implemented in the form of a FORTRAN 77
software program. Computer simulations of both the full scale Hawk
aircraft and scaled wind tunnel model were written. MSR was found to
produce perfect derivative estimates when using noise-free data
produced by the aircraft simulations.
Various mathematical models were produced to represent the reduced
order small perturbation equations of motion for the Hawk in the wind
tunnel. Different methods for re-constructing the perturbation
variables were implemented. Although the MSR procedure did not perform
optimally with experimental data, some insight into both the MSR method
and the practical difficulties associated with using a small dynamic
rig has been gained.
