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HOMEWORK
PHAK CHAPTER 10JEPPESEN Chapter 8 section A
GLEIM CHAPTER 55.1-5.6
ASA CHAPTER 88-21 TO 8-35
The next test will be 100% ASA
Private Pilot Ground School Class #7
Content of Lesson
Meterlogical conditions and their effect on performance.
Density altitude effect on takeoff and climb.
Use of Various performance charts.
Safe and efficient operation of aircraft
Meterological Conditions
Weather greatly effects aircraft performance.
Wind, Atmospheric Pressure, Temperature, Humidity all affect how an aircraft performs.
TermsDensity altitude; measurement of
the density of the air expressed in terms of altitude. Density altitude is pressure altitude corrected for a non standard temperature.
High density altitude; a condition in which the air is less dense
High Density Altitude
4 things contribute to a high density altitude:
1. High field elevationDensity altitude is increased by
an increase in field elevation i.e. Seattle to Denver
18,000 feet atmospheric pressure is roughly halved
High Density Altitude
2. Low pressure systemDensity altitude is increased
by a decrease in pressureLow pressure weather system
= lower pressure
High Density Altitude
3. High temperatureDensity altitude is increased
by an increase in temperatureSpreads out molecules makes
air less dense
High Density Altitude
4. High humidityDensity altitude is increased
by an increase in humidityA given volume of dry air is
more dense than the same volume of moist air
High Density Altitude
The atmosphere is 78% nitrogen 21% oxygen 1% inert gases
Water vapor varies from almost none to 5% by volume
Water vapor then displaces oxygen molecules
High vs. Low Density Altitude
Hot, humid, high elevation and low pressure = High density altitude
Cold, dry, low elevation and high pressure = Low density altitude
High Density Altitude
Airplane effected several ways:1. Wing is less effective2. Propeller is less effective3. Engine puts out less
horsepower
Performance is effected High Density Altitude:
1. Rate of climb is lower2. Time to climb is longer3. Takeoff roll is longer4. Acceleration is slower5. Higher true airspeed means
faster approach 6. Longer landing roll
So how can the pilot minimize the effects of High
density altitude?1. Leave in the morning when its
cooler2. Off load some baggage and or
passengers3. Make two trips4. Take a higher performing
aircraft
Continued
5. Lean the engine for more horsepower unless POH says not to
6. Do your calculations ahead of time and make the go, no go decision early.
Do not let the people you travel with or Boss make you compromise safety
Density Altitude
The primary reason for computing density altitude is to determine aircraft performance
Remember Density altitude is Pressure altitude corrected for nonstandard temperature
Density Altitude
It can be found 2 ways1. Use the chart2. Use the computer
Standard Atmosphere
29.92, 1013.2 millibars, 14.69 psi standard sea level
59 F or 15 C standard temp. at sea level
Computing Density Altitude
1st step: convert elevation or altitude to pressure altitude.
can be done by setting 29.92 into altimeter or by subtracting 29.92 from the current pressure then multiplying by 1000 then either adding or subtracting from the current pressure value
Computing Density Altitude
E.G. Field elevation 1185 pressure 30.55
29.92- 30.55 - .63 x 1000 = -630’1185 + -630 = 555’ Pressure
Altitude
Computing Density Altitude
So the airplane thinks its flying at 555 feet because of the extra pressure
555 is closer to sea level than 1185
Computing Density Altitude
E.G. Field elevation 1185 pressure 29.62
29.92-29.62 .30 x 1000 = 300 1185 +
300 = 1485
Computing Density Altitude
So the airplane thinks its flying at 1485 feet because of the decrease in atmospheric pressure
2nd step: Take the pressure altitude and the temperature at your elevation or altitude and follow the lines on the density altitude chart until they intersect.
DENSITY ALTITUDE CHART
Summary of Effects of Density Altitude (P153)
Low-Density Altitude - made with Low temperature, Dry air and High Pressure
High-Density Altitude - made with high temperature, humid air, low pressure.
Performance ChartsConversion chartsWind component
chartTake-off distance
chartClimb chartTime, Fuel and
distance to Climb chart
Cruise Power Settings
Cruise SpeedsRange/Endurance
ChartsLanding Distance
Chart
Crosswind chart
B-19 CROSSWIND
DENSITY ALTITUDE CHART
Takeoff distance chart
Cruise Performance Chart
Landing Distance Chart
Landing Distance
Vy & Vx
Vy=best rate of climb (most altitude over any unit of time)
Vx=best angle of clime (most altitude over a given distance)
B-19 Vy=72 knotsVx=65 knots
Maximum Range & Endurance
Maximum Range=gives longest distance for a given amount of fuel.
Maximum Endurance=gives you most time for a given amount of fuel.
PERFORMANCE #2
B-19 CHARTSAirspeed CalibrationAltimeter CorrectionCrosswindTakeoff DistanceClimb chartsCruise Landing distance charts
BRING A CALCULATOR, B-19 MANUAL AND SECTIONAL CHART NEXT CLASS PLEASE
AIRSPEED CALIBRATION
ALTIMETER CORRECTION
CROSSWIND CHART B-19
Sample X-Wind problemsRunway 18, Wind
210@25ktsWhat is the
headwind & crosswind components?
Runway 22, wind 260@32 knots
What is the headwind and crosswind components?
Sample X-Wind problemsRunway 18, Wind
210@25ktsWhat is the
headwind & crosswind components?
Runway 22, wind 260@32 knots
What is the headwind and crosswind components?
H.W. = 21.65 knotsC.W. = 12.5 knots
H.W. = 5.56 knotsC.W. = 31.51 knots
Takeoff Distance B19
Takeoff Distance B19GivenWind 0 knots, Temp. 7 degrees C, Pressure Altitude 2000 ftWhat is the Takeoff distance?
Takeoff Distance B191 degree = 106211 degrees = 11787 degrees = ? (you need to interpolate)
Takeoff Distance B19
1 degree = 106211 degrees = 11787 degrees = ? (you need to interpolate)
11-1=10 1178-1062=11611-7= 4 116x.4=46.44/10 or .4 1178-46.4=1131.6
Takeoff Distance B19
1 degree = 106211 degrees = 11787 degrees = ? (you need to interpolate)
11-1=10 1178-1062=1167-1= 6 116x.6=69.66/10 or .6 1062+69.6=1131.6
Takeoff Distance B19What if the Pressure Altitude was 1000 feet instead of 2000 feet
We have already solved for 2000 feet the next step would be to solve for sea level for 7 degrees C.
15-5=10 1030-930=10015-7= 8 100x.8=808/10 or .8 1030-80=950
Takeoff Distance B19 (7 Degrees)
Takeoff distance at 2000 feet Pressure altitude = 1131.6
Takeoff distance at sea level = 950
Last step is to interpolate for 1000 feet Pressure altitude
2000-0=2000 1131.6-950=181.62000-1000= 1000 181.6x.5=90.81000/2000 or .5 1131.6-90.8=1040.8
CLIMB CHARTS B19
CRUISE CHART B19
LANDING DISTANCE CHART B19
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