Private Pilot Flight Training and Instruction Flight Training Article Library | Back To 4VFR.COM Performance Sheet ASEL Compute weight and balance with gross takeoff weight___________ Center of gravity location ________ Gross landing weight __________ Center of gravity location _________ Shift weight from _________ to the _____________New center of gravity locaton _________ Cross Country Flight Plan Total distance is __________Total time is ____________Total fuel used is __________ Total fuel remaining including reserve ___________Is a fuel stop required for this flight? ____ Plan takeoff over a 50’ obstacle at full gross weight at sea lever with an outside air termperature of 30 degrees centigrade ____________ Discuss density altitude and performance. Plan a landing over a 50 foot obstacle at landing weight at 3000’ pattern altitude with an a standard outside air temperature. Whis is the best endurance altitude and power setting for this aircraft? _________ What is the range of this aircraft at 75% power? ________ amd 65% power?_______ Weight affects the stall speed of an airplane. Book figures are at gross weights. An overweight plane will stall before the book figure; a light plane will stall at a slower speed. Flight in excess of gross weight is prohibited. Alaska allows 10% over for survival gear. Most aircraft are close to gross when they have full fuel. Reduction of fuel load is the best adjustment factor. Controls are designed and certified to perform properly within a certain balance/speed range. Va or maneuvering speed (abrupt control movement allowable) is published for gross weight only. An out-of-balance plane at low speeds may not have the effectiveness required for control. This means that the elevators may not be able to properly raise the nose of an airplane while taking off or landing. They may not be able to effectively lower the nose in climb, slow flight or landing. All performance figures are predicated on a properly balanced aircraft. An aircraft that is out-of-balance causes performance figures to change for the worse. This is especially true regarding fuel consumption. Takeoff data is figured for standard conditions with factors added for wind velocity and runway conditions. Since conditions are seldom standard, you must compute any effects of density altitude or non-standard conditions. Climb is figured likewise. The performance increases at roughly the percentage of the weight reduction. Fly 10 % below gross weight expect takeoff climb and range to improve about 10%. Fuel consumption may be determined by power applied. Altitude normally decreases the air available to the fuel mixture making possible a reduction (leaning) of the mixture. At altitude the engine has less power and consumes less fuel while at the same time getting more distance. In no wind/tail wind conditions it is more economical to fly high. Density altitude conditions affect fuel/air relationships as well. Fuel consumption, leaned, is about .44 pounds of fuel per hour per horsepower. For the C-150 this gives, .44 X 100 hp /6 lb. per gal = 7.3...gallons per hour. With 22.5 useful capacity and the tanks not really topped off (prevents waste) three hours flight time with the required 1/2 hour daytime reserve comes up short. The manual gives more optimistic figures predicated on lower horsepower available at altitude. The true air speed (TAS) is calibrated airspeed (CAS) corrected for air density. This is the manufacturers manual speed, which you use for navigational purposes to find ground speed. For practical use it is too optimistic due to the differences between new and abused (sic) aircraft. The service ceiling is required knowledge since it makes no sense to plan a flight across terrain above aircraft capability. At service ceiling the plane can still climb 100 feet per minute. Density altitude factors can greatly affect both this ceiling and the absolute ceiling. The V speeds are determined through exhaustive study by the manufacturer to be the best speeds for a specific desired performance. While these speeds may vary somewhat with aircraft weight they are required knowledge as a base for performance. V speeds are indicated speeds, which are to be flown within the ranges, specified in the Practical Test Standards. V speeds are usually found near the front of the aircraft annual with explanation. It is best to locate, and know for the flight test, the significance and number of all the V speeds such as: Vx, Vy, Va, Vne, Vfe, etc. Broad performance - specifications of the aircraft are on back of the front cover or on the first few pages of the manual. For specific performance under conditions see the chapter index. Putting labeled tabs on certain charts related to takeoff, landings, emergency, and power settings would make location easier. FAR 91.103 requires that we calculate required runway lengths for takeoff and landing. You need not know everything in the manual but you must be able to locate desired information efficiently. It is not recommended to ever fly without a manual available. Va, maneuvering speed, is slower at lighter weights. So are stall speeds. The maneuvering speed is a limit on control movement. Since the aircraft loading moments between control pressures and turbulence pressures differ, the allowable turbulence speed may be a bit higher than Va. Since the use of flaps and slips varies so widely between aircraft, it is important to know what is specifically required, permitted or prohibited for your aircraft. The stronger the cross winds the fewer degrees of flap recommended. The maximum demonstrated crosswind component is not a limitation. It is something required as a demonstration. Make sure to know under what conditions slips are allowed or not. For takeoff be sure to know the required flap setting for specific performance. Partial and full flap settings may have different airspeed limits. Application of flaps before slowing to required speeds will be harmful to the aircraft. The way flaps are removed in flight depends upon the airspeed. Below Vx they should be milked off slowly until Vy is obtained while holding altitude. At Vy or higher removing the flaps all at once should not create a problem. It is advisable to have your own manual for every aircraft you fly. Written by Gene Whitt Flight Training Article Library | Back To 4VFR.COM