Chapter 11 – Aircraft Performance
Chapter 8 in Study Guide
By
Michael Philip
Table of Contents
Slide 3 → Introduction
Slide 4-5 → Atmosphere
Slide 6 → Performance
Slide 7-8 → Range Performance
Slide 9 → Takeoff Performance
Slide 10 → Landing Performance
Slide 11-13 → Performance Charts
Slide 14 → Conclusion
Introduction
Factors affecting aircraft performance:
• Aircraft weight
• Atmospheric conditions
• Runway environment
• Forces on aircraft
Figure 1: Forces on Aircraft
(https://www.cfinotebook.net/notebook/aero
dynamics-and-performance/aerodynamicsand-performance)
The use of performance data, which is obtained from the
Aircraft Flight Manual/Pilot’s Operating Handbook, is
mandatory for safe and efficient operation.
Atmosphere
Less dense air → Less power, thrust, and lift
Figure 2: Standard Sea Level Pressure
(Figure 11-1 in Handbook)
Density Altitude
Pressure Altitude
Density increases
if…
Pressure
increases
Or
Temperature
decreases
Figure 3: Field Elevation vs.
Pressure (Figure 11-3 in
Handbook)
Figure 4: Density Altitude Chart
(Figure 11-4 in Handbook)
Performance
High speed → Significantly increased drag
Figure 5: Drag vs. Speed
(Figure 11-5 in Handbook)
The aircraft climbs (gains PE) using excess power above that required to maintain level flight
OR
The aircraft climbs by converting airspeed (KE) to altitude (PE)
Max angle of climb (AOC) and rate of climb (ROC) occur at full throttle and where excess power
above the required amount is at a maximum.
Climb performance affected by:
Weight, Altitude, and Design Configuration
Figure 6: Max
AOC vs. Max
ROC (Figure
11-7 in
Handbook)
Range Performance
Specific Endurance = Flight Hours / Pounds of Fuel = 1 / Fuel Flow
Specific Range = Nautical Miles / Pounds of Fuel = Knots / Fuel Flow
Figure 7: Airspeed for Maximum Endurance (Figure 11-11
in Handbook)
Range Performance
Figure 9: Effects
of Altitude (Figure
11-13 in
Handbook)
Figure 8: Effects
of Weight
(Figure 11-12 in
Handbook)
Figure 10: Region of Reversed
Command in Lower Speed Phase
(Figure 11-14 in Handbook)
Takeoff Performance
Minimum hydroplaning speed = 9 * sqrt(Tire pressure in psi)
Gradient or slope of the runway is the amount of change in runway height over the length of the runway.
Engine pressure ratio (EPR) is the ratio between exhaust pressure (jet blast) and inlet (static) pressure on
a turbo jet or turbo fan engine. More EPR → More Power.
Increased weight affects takeoff: Higher lift-off speed; Greater mass to accelerate; Increased resistance
(friction/drag).
Headwind
→Smaller takeoff
distance
Tailwind → Greater
takeoff distance
Figure 11: Effect of Wind on Takeoff/Landing
(Figure 11-19 in Handbook)
Increased density altitude leads to:
Greater takeoff speed
Decreased thrust and reduced net
accelerating force
Landing Performance
Aerodynamic braking better than mechanical because no wear and tear, but
minimum landing distance requires both.
Increased weight → Increased landing velocity/distance
Below a specified minimum landing speed → may stall, be difficult to control, or
develop high rates of descent
Excessive speed at landing → slightly more controllability, but increase in landing
distance
Landing affected by:
Pressure altitude and temperature
Gross weight
Wind
Runway slope and condition
Performance Charts
Allow a pilot to predict the takeoff, climb, cruise, and landing
performance of an aircraft, but some require interpolation for specific
data.
Interpolating information means that by taking the known information, a
pilot can compute intermediate information.
Figure 12: Cruise Performance Graph (Figure 11-30 in Handbook)
More Performance Charts
Figure 13: Fuel, Time, and Distance to Climb Graph
(Figure 11-25 in Handbook)
Find OAT and trace up to
Pressure Alt. Trace right to
desired metric, and then trace
straight down to get value.
Figure 14: Fuel, Time, and Distance to Climb Chart
(Figure 11-26 in Handbook)
Start at weight, then move over to
correct Pressure Altitude and Rate of
Climb to line up with desired metric.
More Performance Charts
Figure 15: Takeoff Distance Graph
(Figure 11-23 in Handbook)
Find OAT, then trace up to Pressure
Altitude. Move over to vertical Weight
line and trace up to corresponding
value. Repeat for Wind Component and
Obstacle Height.
Figure 16: Wind Component
(Figure 11-31 in Handbook)
Find degree difference between
wind direction and runway. Trace
line from degree value down to
current Wind Velocity value. Then,
draw line straight down and across
to determine Crosswind Component
and Headwind Component.
Conclusion
Topics Discussed:
• Atmosphere
• General/Range/Landing/Takeoff Performance
• Performance Charts
Various factors affect the performance of an aircraft, and
pilots should be highly familiar with how to determine
performance metrics, what they mean, and how to
respond.