Performance Calculations

Question 1

Standard Atmosphere

Answer 1

29.92 15C 1013.2 mb

This is the standard Datum at sea level (can be lower or higher actually at sea level)

Question 2

Altitudes

Answer 2

Indicated: Indicated on the Altimeter

True: the height above sea level (indicated corrected for non standard temperature and pressure)

Absolute: vertical distance of the aircraft above ground level

Pressure: the height above the standard datum plane (29.92) Indicated altitude corrected for non standard pressure

Density: pressure altitude corrected for nonstandard temperature and pressure (when standard pressure conditions exist density altitude and pressure altitude are equal)

Question 3

Airspeeds

Answer 3

Indicated: the speed shown on the airspeed indicator

True: the actual airspeed through undisturbed air (Indicated Airspeed Corrected for Air Density= corrected for temperature difference and pressure difference)

Calibrated: indicated airspeed corrected for installation and instrument error

Ground: the actual speed of the airplane over the ground (true airspeed adjusted for the wind)

Question 4

How can we affect Lift?

Answer 4

L = (1/2 Pv^2) CL*SA

P= density altitude
V^2 = velocity
CL = center of lift (A.O.A)
SA = Surface Area (Flaps)

Question 5

Density Altitude

Answer 5

High Density Altitude: Low Pressure, High Temperature (more molecular movement thins atmosphere), High Humidity (water molecules displaces oxygen thinning air)
BAD ENGINE PERFORMANCE & LANDING AND TAKE OFF PERFORMANCE

WHY ENGINE SO BAD?
Thin Air = Low Pressure
Less Airflow = Less Efficient Engine (less efficient combustion)
Less Airflow = Less Airflow for Prop to Chop
Less Airflow = Over Wings for Lift

Low Density Altitude: High Pressure, Low Temperature, Low Humidity
GOOD ENGINE PERFORMANCE & LANDING AND TAKE OFF PERFORMANCE

Question 6

Density Altitude Effects on Takeoff/Landing

Answer 6

High Density Altitude = longer ground roll, poorer engine and airfoil performance, poor climb performance

Low Density Altitude = shorter ground roll, better engine and airfoil performance, better climb performance