Performance and Limitations

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| | **Importance of Performance Data** | · **Need to know if the aircraft is capable of performing actions** · **Calculate if able to takeoff and land at different airports** · **Know if you’re able to clear obstacles** · **Key performance data** o **Takeoff and landing distance** o **Rate of climb** o **Ceiling** o **Payload** o **Range** o **Speed** o **Maneuverability** o **Stability** o **Fuel economy** | | atmospheric structure and conditions | · Standard day o 15c 29.92inHG | | pressure and density altitude | · Pressure altitude o Hight above the standard datum plane o The altitude you would get if you set the altimeter to 29.92 o Good for determining aircraft performance · Density altitude o Pressure altitude corrected for nonstandard temperature o As the density of air increases, the performance increases o Density increases as temperature decreases o Under standard conditions, pressure and density altitude will be the same o Humidity will make the air less dense o ![Chart Description automatically generated](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image001.png) | | effect of airplane configuration on performance | · Extended flaps or landing gear will always decrease performance · Plane must be flown in the correct configuration or performance will not be as good as in POH | | Thrust vs Power | · Thrust o Force or pressure exerted on an object o Measured in pounds or newtons · Power o Measurement of the rate of performing work or transferring energy o Measured in horsepower or kilowatts · Think of power as the motion a force (thrust) creates when exerted on an object over a period of time | | Kinetic and potential energy | · Kinetic energy o Found from the speed of the aircraft o KE = 1/2 mv^2 · Potential energy o Found from altitude o PE = mgh · “airspeed is money in the pocket, altitude is money in the bank” | | effect of airplane condition on performance | · Straight and level o Equilibrium must be attained by lift equal to aircraft weight, and thrust equal to drag o ![Diagram Description automatically generated](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image002.png)![Diagram Description automatically generated](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image003.png) · Climb performance o More weight will always decrease climb performance o Occurs when an aircraft gains PE by increasing altitude o Factors § Climbing using excess power above that required to maintain level flight § Converting airspeed (KE) to altitude (PE) o Reasons to calculate § Obstacle avoidance § Higher altitudes can provide better weather and better fuel economy o ![Diagram Description automatically generated](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image004.png) o Max angle of climb § Occurs at the airspeed and angle of attach combination which allows the maximum excess thrust § Differs for different aircraft types § For propeller aircraft, generally close to stall speed § ![Diagram Description automatically generated](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image005.png) o Max rate of climb § Occurs at the airspeed and angle of attack combination which allows for maximum excess power § ![Diagram Description automatically generated](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image006.png) | | Range performance | · The ability of an aircraft to convert fuel energy into flying distance · Specific range o NM of flying distance versus the amount of fuel consumed o NM/pounds of fuel o Knots/fuel flow · Range involves consideration of flying distance, while endurance involves consideration of flying time · Specific endurance o Flight hours / pounds of fuel · Maximum range will be at LD max · ![](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image007.png) · Range can change based on o Gross weight o Altitude o External aerodynamic configuration of the aircraft · Maximum range o Occurs where the ratio of speed to power required is greatest o Occurs at LD max o Weight changes the values of airspeed and power required to obtain LD max o ![](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image008.png) · Maximum endurance o Point of minimum power required since this would require the lowest fuel flow | | takeoff and landing performance | · Factors o Function of the stall speed or minimum flying speed o The rate of acceleration/deceleration during the takeoff or landing roll o The weight of the aircraft · | | effect of pilot technique on performance | · Need to know that performance calculations are made with a brand new airplane and perfect pilot performance · Encourage multiplying numbers by a multiple to be more conservative · 50% is a good amount to increase the numbers | | effect of airport environment on performance | · Runway surface o Performance charts assume a paved, level, smooth, and dry runway surface o Gradient or slope § The amount of change in runway height over the length of the runway § Expressed as a percentage o Any surface that is not hard and smooth increases the ground roll during takeoff | | region of reversed command | · When a higher airspeed requires a lower power setting and a lower airspeed requires a higher power setting to hold altitude · Occurs below the speed for maximum endurance · ![A picture containing diagram Description automatically generated](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image009.png) · Need to be extremely careful when operating in this region | | hydroplaning | · Exists when an airplane has landed on a runway surface contaminated with standing water, slush, or wet snow · Have serious adverse effects on ground controllability and braking efficiency · Dynamic hydroplaning o When there is a film of water on the runway that is at least one tenth of an inch deep o Water layer builds up an increasing resistance to displacement, resulting in the formation of a wedge of water beneath the tire o Vp (hydroplaning speed) the water pressure equals the weight of the airplane, and the tire is lifted off the runway surface § Equal to 8.6 times the square root of the tire pressure in PSI o Once started, can persist at lower speeds o ![The 3 Types Of Hydroplaning, And How To Prevent Them \| Boldmethod](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image010.jpg) · Reverted rubber hydroplaning o Steam hydroplaning o Occurs during heavy braking that results in a prolonged locked-wheel skid o Only a thin film of water on the runway is required to facilitate this type of hydroplaning o Tire skidding generates enough heat to cause the rubber in contact with the runway to revert to its uncured state o Heated water turns into steam, which supports the airplane off the runway o ![The 3 Types Of Hydroplaning, And How To Prevent Them \| Boldmethod](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image011.jpg) · Viscous hydroplaning o Can occur with very thin layer of water (1/1000th of an inch) o Occurs at much lower speed than dynamic hydroplaning o Requires a smooth surface, like accumulated rubber from previous landings o Can have the same friction coefficient as ice o ![viscous](file:////Users/andrehebra/Library/Group%20Containers/UBF8T346G9.Office/TemporaryItems/msohtmlclip/clip_image012.jpg) | | performance speeds | · Vx: best angle of climb · Vy: best rate of climb |