1. Design Chapter 8 Second half

2. Landing Gear Configuration Tailwheel –PROS simple to make & install added very little weight and drag –CONS complicates landing & taxiing operations yawing tendency is amplified

3. Landing Gear Configuration Tricycle –PROS CG is ahead of the main gear & adds stability on pitch & yaw motion hard impact on nose gear causes a pitch down motion decreasing lift yawing motion is counteracted by the forward CG improved handling qualities greater visibility

4. Landing Gear Configuration Tricycle –CONS Nose gear has to withstand considerable impact Its size and location add a fair amount of drag The main gear is fairly aft and complicate attachment to the rest of the plane

5. Tail Design The purpose of the tail surfaces is to provide adequate stability and control. –The horizontal tail provides longitudinal stability and control The vertical tail give the same qualities in the directional sense The total horizontal tail surface provides longitudinal stability The elevator provides pitch control Rudder for yaw stability

6. Tail Design Conventional vertical tail –the single vertical fin mounted above the horizontal stabilizer –a large fin can result in significant rolling moment from rudder deflection Twin vertical fin –two smaller fins and contribute to directional stability –endplate effect on the horizontal stabilizer make it more efficient

7. Tail Design T-Tail purpose/advantage –to place it out of the wing’s downwash downwash reduces the stabilizing effect of the horizontal tail & this is greater at high angles of attack at full stall the downwash ceases and the wing’s wake flows directly aft.

8. Tail Design T-Tail Disadvantages –The T-tail experiences a sudden loss of effectiveness and a rapid pitch-down motion results in a deep stall. –T-tail also has the additional weight required for heavier structure necessary to support the horizontal tail in this position

9. Tail Design V-Tail –A single surface on either side of the centerline is canted upward to provide horizontal and vertical tail effects –the vertical projection provides longitudinal stability –the horizontal projection provides directional stability –This arrangement reduced the drag slightly over the conventional tail arrangement

10. Tail Design V-Tail –CONS The main objection is the extremely complex control system required to get pitch and yaw control from a single control surface. The V-tail is also susceptible to Dutch roll tendencies

11. V-Tail & T-Tail Both popular on sailplanes to keep the tail surfaces high to keep from being damaged in landing Both also have good spin recovery characteristics

12. First Estimation Weight –best place to start is gross weight; so many other parameters depend on this value –figure 8-15 p. 235, Table 8-1 p.236 Wing –wing loading or weight to wing area ratio

13. First Estimation Power –power required, horsepower Range –fuel consumption

14. Initial Estimation Example Page 240-243 Payload Cruise Range Certifiable under FAR part 23

15. Computer-Aided Design Aerodynamic engineers use computers to model flow patterns. Panel Method: –Three-dimensional bodies can be molded as a collection of flat panels and fluid flow relations applied to each of these panels. –Figure 8-17 p. 245 –Finite element methods simulate large structure with small elements connected by nodes.

16. Quiz on Chapter 8 Take out a sheet of paper Include today’s date and your name

17. Quiz on Chapter 8 Compare and contrast the t-tail and the v- tail. Why do aerodynamic engineers use Computer aided design (CAD)?