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Aircraft Performance

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Maximum endurance airspeed is not the minimum airspeed. Wind does not effect Endurance ... Best Glide Airspeed L/DMAX. Descent. Considerations. Altitude to lose ... – PowerPoint PPT presentation

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Title: Aircraft Performance


1
Aircraft Performance
  • Dave Horne, CFI
  • Shoreline Flying Club

2
Lesson Objectives
  • Understand factors affecting an aircrafts
    performance to include pressure altitude, density
    altitude, and humidity
  • Be able to explain how the condition of the
    runway affects our take off and landing
    performance
  • Understand the difference between range and
    endurance
  • Be able to use performance charts to calculate
    our take off and landing distances
  • Be able to understand how to interpolate data if
    needed

3
Associated Text
  • PHAK
  • Chapter 9
  • Aircraft POH
  • Section 5

4
Factors Affecting Performance
  • Air Density
  • Humidity
  • Wind
  • Runway Environment

5
Pressure Altitude
  • Pressure Altitude
  • Height above a standard datum plane (29.92Hg)
  • To Calculate
  • 29.92 the current alt setting
  • Multiply by 1000 then add to your field elevation

6
Density Altitude
  • Pressure Altitude corrected for non-standard
    temperature
  • Essentially it is the altitude that the airplane
    thinks it is at

7
Density Altitude
  • Pressure decreases, Density Altitude increases
  • Pressure increases, Density Altitude decreases
  • A decrease in air density means a high density
    altitude and an increase in air density means a
    lower density altitude

8
Density Altitude
  • To Calculate
  • Determine pressure altitude
  • Correct for non-standard temperature variations
  • Use charts or your E6B to calcuate

9
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10
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11
Air Temperature and Density
  • Cold
  • Air is more dense
  • Hot
  • Air is less dense

12
Humidity
  • Percentage of water vapor in the air

13
Humidity and Density Altitude
  • High Humidity
  • Air becomes less dense density altitude
    increases
  • Low Humidity
  • Air becomes more dense density altitude
    decreases

14
Wind
  • Headwinds
  • Increase takeoff performance
  • Shorter distance
  • Increase landing performance
  • Shorter distance
  • Decrease Range
  • Tailwinds
  • Decrease takeoff performance
  • Longer distance
  • Decrease landing performance
  • Longer distance
  • Increase Range

15
Turbulence
  • Decreases takeoff maneuverability and climb
    performance
  • Rates of Climb / Descent, sometimes erratic
  • Recovery Capability of Aircraft (Go-Around)

16
Runway Slope
  • Upsloping Runway
  • Increase takeoff distance
  • Decrease landing distance
  • Downsloping Runway
  • Decrease takeoff distance
  • Increase landing distance

17
Runway Condition
  • Dry, Paved Runway Standard for Performance
    Determination
  • Grass Runways
  • Increase takeoff distance
  • Increase landing distance
  • Poor braking
  • Gravel Runways
  • Nil effect on takeoff distance
  • Increase landing distance
  • Poor braking
  • Wet Runways
  • Nil effect on takeoff distance
  • Increase landing distance
  • Poor braking
  • Hydroplane hazard

C-17 Globemaster departing Dirt Runway
18
Aircraft Configuration
  • Flaps
  • Landing Gear
  • Cowl Flaps
  • Spoilers

19
Aircraft Design
  • Airplanes are designed with certain performance
    characteristics in mind
  • Antonov AN-2 Colt

20
Pilot Technique
  • The smoothness and accuracy of the pilot can have
    a substantial effect on aircraft performance

21
Performance Phases of Flight
  • Take Off
  • Climb
  • Cruise
  • Range
  • Endurance
  • Glide
  • Decent
  • Landing

22
Take Off Performance
  • Terms
  • Ground Roll distance from the start of
    acceleration to where the aircraft leaves the
    ground
  • Distance to clear 50 Obstacle Ground Roll plus
    initial climb at VX (Best Angle of Climb) to 50
    feet

23
Take off Performance - Factors
  • Weight
  • Center of Gravity
  • Density Altitude
  • Wind
  • Runway Slope
  • Runway Condition
  • Pilot Technique

24
Take Off Performance - Charts
  • Read all associated text and account for all
    variables
  • Short Field T/O
  • Flaps 10 on Cessna
  • Flaps 25 on Warriors

25
Climb Performance
  • Vx Best Angle of Climb
  • Gain altitude over a short distance
  • Based on excess thrust
  • Vy Best Rate of Climb
  • Gain altitude over the shortest period of time
  • Based on excess power

26
Climb Performance
  • Cruise Climb
  • Increases Ground Speed
  • Increases Forward Visibility
  • Better Engine Cooling

27
Ceiling
  • Absolute Ceiling altitude where the aircraft
    will no longer climb
  • Altitude where VX and VY are the same
  • Service Ceiling altitude where the maximum rate
    of climb is 100 feet per minute (fpm)
  • Maximum Rate of Climb Chart

28
Cruise
  • Normal Power Settings 55 to 75
  • Using power settings above 75
  • Increases fuel consumption
  • Increases operating temperatures
  • Increases engine wear
  • Decreases engine time between overhaul (TBO)
  • Performance Factors
  • Center of Gravity
  • Weight

29
Range
  • Greatest distance an aircraft can travel
  • Aircraft is operated at L/DMAX
  • Performance Factors
  • Aircraft Weight
  • Wind Conditions

30
Endurance
  • Greatest amount of time the aircraft can remain
    aloft
  • Minimum fuel consumption to maintain altitude
  • Maximum endurance airspeed is not the minimum
    airspeed
  • Wind does not effect Endurance

31
Fuel Economy
  • Increases altitude increases economy because of
    leaned mixture
  • Cruise Performance
  • 55 Best Economy
  • 65 Best Economy
  • 75 Best Power

32
Gliding
  • Best Glide Airspeed L/DMAX

33
Descent
  • Considerations
  • Altitude to lose
  • Time and Distance to destination
  • Rate of Descent
  • Turbulence
  • Aircraft Configuration

34
Landing Performance
  • Terms
  • Ground Roll distance from touchdown to the point
    where an airplane comes to a complete stop
  • Distance to clear a 50 Obstacle total distance
    to clear a 50 obstacle, touchdown, and come to a
    complete stop

35
Landing Performance - Factors
  • Weight
  • Center of Gravity
  • Density Altitude
  • Wind
  • Runway Slope
  • Runway Surface Conditions

36
Landing Performance - Factors
  • Pilot Technique
  • Braking
  • Stabilized Approach
  • Turbulence
  • Increase approach speed
  • During gusty conditions, increase approach speed
    by ½ the gust factor
  • Aircraft Configuration
  • Flaps
  • Approach Speed reduced
  • Approach Angle increased
  • Aerodynamic Breaking

37
Landing Performance - Charts
  • Types of Charts
  • Landing Ground Roll Distance
  • Used for Normal Landing
  • Landing Distance
  • Used when obstacle clearance is necessary

38
Landing Performance - Notes
  • During turbulence and high winds increase
    approach speed
  • Runway Surfaces

39
Performance Charts
40
Crosswind
  • Step 1
  • Figure out the difference in degrees from the
    runway and the winds
  • Step 2
  • Draw a line down to the speed
  • Step 3
  • Draw lines across to the headwind and crosswind
    components

41
Crosswind - Example
  • Runway 17
  • Wind 240_at_25

42
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43
Activity
  • Calculate the t/o distance over a 50foot obstacle
    under the following conditions
  • Max weight
  • 25 C
  • Pressure Altitude 2500 feet
  • 9 knot headwind
  • Dry, Paved, Level runway

44
Activity
  • Calculate the Landing Distance over a 50 foot
    obstacle with the following conditions
  • 2000 lbs
  • 15C
  • 2500 foot pressure altitude
  • 5 knot tailwind

45
Summary Statements
  • Density Altitude can hurt your aircrafts
    performance
  • Aircraft performance charts are not perfect be
    conservative with your estimates
  • Interpolation of data may be needed to provide a
    more accurate estimate of your performance data
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