Ministry of Technology

A piloted simulation study of the handling characteristics of the B.A.C. 221 aircraft in the approach configuration was made in preparation for the first flight of the aircraft. The simulation included a simpli~ed representation of the outside visual world, and cockpit motion in pitch and roll. Values of the aircraft's lateral derivatives and moments of inertia were varied to allow for uncertainties in the predicted aircraft characteristics. Optimum control gearings and centre of gravity position for first flight were also investigated. The Fairey Delta 2 aircraft, from which the B.A.C. 221 derives, was also simulated to allow comparison with existing flight experience. Since the completion of the simulation the first flight of the B.A.C. 221 has made possible a retrospective assessment of the value of the simulation. Appendix Comparison of the behaviour of the simulated Fairey Delta 2 with initial impressions obtained in flight by Fit. Table 1 Dimensions and inertia data for the B.A.C. 221 and Fairey Delta 2 aircraft pertinent to the simulation Table 2 Parameters varied in the B.A.C. 221 simulation List of Illustrations Detachable Abstract Cards 1. Introduction. The B.A.C. 221 is a research aircraft built to study the behaviour of a slender wing shape at both high and low speed. It has been developed from the Fairey Delta 2, a 60 ° tailless delta wing aircraft 1'2'3'4, by modifications which include a new wing fitted to a lengthened fuselage, and a new undercarriage, but it retains the Rolls Royce Avon RA28 engine and the fin of the Fairey Delta 2. Fig. 1 shows the plan views of the two aircraft and Table 1 compares the geometric and inertia data pertinent to this simulation. The Fairey Delta 2 is generally judged to be a very demanding aircraft to fly and the modifications into an Ogee wing design give it, in some respects, even more extreme characteristics. It was felt, therefore, that it would be wise to obtain, in advance of first flight, an assessment of the controllability of the B.A.C. 221 on a simulator. The tests were restricted to the approach configuration, as this was expected to be the most critical flight condition. Consequently the simulation covered the speed range up to 175 kt and represented the aircraft with undercarriage locked down and nose fully drooped. One of the aims of the experiment was to find optimum values for the centre of gravity position, the elevator …