1. 1 Lecture 7: Stability & Control Jason Mickey For AE 440 A/C Lecture September 2009

2. 2 S&C Responsibilities Select/design/size all control surfaces, e.g. horizontal tail, vertical tail, etc. (sizes to aerodynamics & configuration Determine/Ensure static margin range for all flight conditions Evaluate longitudinal and lateral stability (suggest needed changes to configuration) Specify avionics and any digital control system (weight/size to internal configuration) Evaluate dynamic stability (phugoid & short period) and evaluate flying qualities (e.g. with a flight simulator)

3. 3 Control Surface Sizing Horizontal tail, elevator Vertical tail, rudder Ailerons

4. 4 Longitudinal Moments Raymer, Fig. 16.3

5. 5 Types of Tails Raymer, Fig. 4.30

6. 6 Tail and Control Surface Sizing (Raymer)

7. 7 Neutral Point (Raymer) Find such that for all a

8. 8 Elevator to Trim Find such that Raymer, Fig. 16.18

9. 9 Yaw and Roll Moments

10. 10 Stability and Handling Qualities Static stability Dynamic stability Handling qualities

11. 11 Stability

12. 12 Cooper-Harper Scale

13. 13 Avionics

14. 14 Samples of Stability and Control from Previous PDRs

15. 15 Tail and Control Surface Sizing Table 5.2.1 Horizontal Tail Dimensions ConfigurationArea (ft 2 )Span (ft)Mean Chord (ft) Pusher26.7510.72.5 Tractor22.839.132.5 Twin-Boom19.417.312.5 Table 5.2.2 Vertical Tail Dimensions ConfigurationArea (ft 2 )Span (ft)Mean Chord (ft) Pusher12.845.142.5 Tractor13.75.552.5 Twin-Boom15.074.382.5

16. 16 Tail and Control Surface Sizing

17. 17 Static Margin Table 5.41 Power-Off Static Margin (%) Configuration1 Pilot2 Pilots Pusher1.939.60 Tractor3.336.98 Twin-Boom4.175.99

18. 18 Suggestions for CR Determine tail-type(s) Finish sizing tail and control surfaces Determine elevator reqt. for takeoff & landing Determine trim points Determine static margin range Investigate static stability Trade studies, e.g. tail size/location vs. trim elevator deflection