Performance

1. Performance

2. Atmosphere • 78 percent nitrogen • 21 percent oxygen • 1 percent other (helium, argon) • Most oxygen is contained below 35,000 feet altitude

3. Atmospheric Pressure • As air becomes less dense, it reduces; • Power, because the engine takes in less air • Thrust because the propeller is less efficient in thin air • Lift, because the thin air exerts less force on the airfoils

4. Atmospheric Pressure • Standard at sea level: 59 Degrees F or 15 Degrees C, Surface pressure of 29.92, or 1013.2 millibars • Standard Lapse rate:3.5 F or 2 C per thousand feet up to 36,000

6. Pressure Altitude • Height above a standard datum plane (29.92) • To find your pressure altitude: • Set altimeter to 29.92 and read indicated • Apply correction factor to the indicated altitude according to reported altimeter setting • Ex. If the reported altimeter setting is 29.82, Subtract it from 29.92 (the standard altimeter) for a difference of 0.1, then multiply that by 1000 and add it to the altitude of the airport (845). Pressure altitude = 945 feet

7. Density Altitude • Pressure altitude corrected for non standard temperature • As density of air increases, it is considered a lower density altitude and vice versa (this is because you are lower to the ground) • As density altitude increases, performance increases • As density altitude decreases, performance decreases • To find density altitude, you must take into account pressure and temperature, you do this when you use your POH to find your performance

9. Climb Performance • Your ability to climb is dependent on excess thrust • Rate of climb depends on flight speed and the inclination of the flight path

10. Climb Performance • Absolute Ceiling • Altitude at which you can no longer climb • Service Ceiling • Altitude at which you are unable to climb at a rate greater than 100 feet

11. Range • How far you can fly on a specific amount of fuel (the furthest distance for the least amount of fuel) • Max Range is obtained at the maximum lift/drag ratio, or L/D max • Unaffected by weight or altitude

12. Endurance • Most amount of time aloft for a given amount of fuel • Max endurance given when at the point o fminimum power required since this would require the lowest fuel flow to keep the airplane in steady, level flight

13. Factors Effecting Range and Endurance • Weight • Density Altitude • External aerodynamic configuration of the airplane

14. Ground Effect • Interference in the three dimensional airflow around the aircraft • Occurs within one wingspan of the ground • Most significant when at a constant low altitude at a low speed in a low wing airplane • Decrease in induced drag allows for greater performance

15. Region of Reversed Command • “Back side of Power Curve” • Power for altitude, Pitch for airspeed • Low speed phases of flight

16. Runway Surface and Gradient • Gravel • Turf/muddy • Potholes/rough pavement • Uphill runway • Downhill runway • Obstructions • Mud, snow, standing water

17. Hydroplaning • Water reduces friction between the tires and the ground, reduce braking effectiveness • Braking and Directional Control lost • Higher speeds increase the hydroplaning hazard because the water can’t move out of the way fast enough • Land into the wind, no abrupt control inputs, brake smoothly – use aerodynamic braking

18. Estimating Performance • Most Performance charts assume that you are using a dry, paved runway in standard conditions. • Your actual conditions as well as piloting experience will influence your actual takeoff and landing performance • POH should still be used as a guide