Aircraft Performance

1. AF 202 Aircraft Performance

2. Objectives • Factors in aircraft performance • Performance tables and graphs • Weight and balance

3. Performance Factors • Obviously aircraft design has a large part to play in aircraft performance • Wing design • Engine size and power • Weight of aircraft • Shape of aircraft

4. Performance Factors • When flying a particular aircraft, those factors do not change • The air you fly in, however, does change • Those changes affect the air’s density

5. Performance Factors • Air density is what needs to be accounted for when determining performance • Density of the air can be affect by many things • Pressure • Temperature • Humidity

6. Performance Factors • As air density decreases, performance decreases. What does this mean? • Engine performance drops due to less air in the intake • Thrust performance drops since there is less efficiency in ‘thin’ air • Lift performance drops because the air exerts less force on the airfoils

7. Performance Factors • To help with determining performance of aircraft, a set of standards was created for all the factors that affect density • These standards are adopted by the International Civil Aviation Organization (ICAO)

8. Performance Factors • 2 degree Celsiusper 1000 feet • 1” Hg per 1000 ft

9. Performance Factors • Air pressure is due to the fact that air is affected by gravity and therefore has weight • Air is a fluid and so the weight is exerted in all directions • Standard weight at sea level is 14.7 psi

10. Performance Factors • When pressure decreases the air can ‘spread out’ leaving less volume. • This will decrease the density of the air • Density of the air is directly proportional to the pressure of the air

11. Performance Factors • Temperature affects density inversely • As temperature increases, density decreases. • As temperature decreases, density increases.

12. Performance Factors • So what happens as we climb • Pressure and temp decrease • It looks as though pressure’s affect on density should be canceled by temperature • The affect of pressure ends up being greater

13. Performance Factors • Humidity also has an effect • Remember humidity is a measurement of how saturated the air is • Water vapor is lighter than air • The more water vapor, the less dense the air is

14. Performance Factors • When it comes to performance charts only temperature and pressure are factored in often times • However humidity should still be taken into consideration especially when your aircraft performance is close to its limit.

15. Performance Factors • So to sum it up… • Pressure decreases, performance decreases • Temperature decrease, performance increases • Altitude increases, performance decreases • Humidity increases, performance decreases

16. Performance Factors • Basically, density altitude isthe altitude the plane ‘feels’it is at • Example: Density altitude is5000 feet at the surface. Thismeans the plane will performas if it were at 5000 feet on astandard day.

17. Performance Factors • Weight will also affect performance, specifically climb performance • More weight means more angle of attack which means more drag • More thrust is required to counter drag and less is available for climb

18. Tables and Graphs

19. Tables and Graphs • There is no standard format to deliver performance data • Some manufacturers use tables and others use graphs • A pilot must also note which factors previously mentioned are even considered in the data.

20. Takeoff Performance • Before figuring out any performance data you need to… • Find related info (temp, pressure, wind, etc.) • READ THE NOTES AND CONDITIONS!!

21. Takeoff Performance • Notice the runway conditions and the type of takeoff • Also note the need to find our headwind

22. Takeoff Performance • Using rwy 36 • Wind 330 @25 kts • Headwind is22 kts

23. Takeoff Performance • Headwind – 22 kts • Pressure Altitude – 2345 • Temperature – 17 degrees

24. Takeoff Performance • Find ground roll at2000 and 3000 ft at 17degrees 2000 ft 1000 – 1080 = 80 80 x 70% (.7) = 56 1000+56 = 1056 3000 ft 1100 – 1180 = 80 80 x 70% (.7) = 56 1100+56 = 1156

25. Takeoff Performance • Next find the ground roll at 2345 feet • 2345 is 34.5% between 2000 and 3000 feet 1056 – 1156 = 100 100 x 34.5% (.345) = 34.5 feet 1056 + 34.5 = 1090.5 feet

26. Takeoff Performance • But you’re not done! Don’t forget wind! • Decrease 10% for each 9 knots • So what percent is for 22 knots? 9(kts) 10(%) 22(kts) x(%) = Cross Multiply 9x = 220 x = 220/9 24.4%

27. Tables and Graphs • Now include the wind reduction 1090.5 x 24.4% (.244) = 261.72 Then subtract it 1090.5 – 261.72 = 828.78 feet

28. Takeoff Performance • How about with a graph?

29. Takeoff Performance

30. Climb Charts

31. Climb Charts • S.L to 8000 • 4000 to 16,000 • 6,000 to 24,000 • Temp of 17 degrees?? Standard Temp at… 4000 = 7 deg (15 – 8) 6000 = 3 deg (15 – 12)

32. Climb Charts

33. Cruise Charts

34. Cruise Performance Pressure altitude: 6,000 feet Temperature: 13 deg Power: 2500 RPM and 23” MP Usable Fuel 460 lb What is the maximum flight time?

35. Cruise Performance At 13 degrees you have 88.5 pph 460lb/88.5 pph = 5.16 hours 5 hours and 12 minutes

36. Cruise Performance

37. Range Profile • Uses percentageof power todetermine maximummiles • Note the zero windcondition

38. Endurance Profile • Uses percentage ofpower to determinemaximum hours of flight • Seems more usefulsince range profilecannot account forwind

39. Landing Distance

40. peace