1. Takeoff Performance Jet Aircraft Performance
Lecture 11
Chapter 5

2. Takeoff
Takeoff Distance is the distanced required to accelerate from zero airspeed up to, or above, stall speed.
The four forces are not in balance during takeoff. (fig p. 139)
Acceleration equals force divided by mass
Net force is in the direction of acceleration
The net force is equal to thrust minus drag & frictional force.

3. Favorable Aircraft Takeoff Conditions
High thrust
Low drag
Low runway tire friction
Low weight
High wing area
High lift coefficient

4. Takeoff Thrust Thrust is greatest when air density is highest
Although higher density increased drag, the increase in thrust is greater; the stall speed decreases
High density, which results from high pressure & low temperature , works favorably for takeoff

5. Favorable Environmental Takeoff Conditions
Smooth runway surface
Level or downhill slope
High pressure
Low temperature
High headwind

6. Balance Field Length
Critical engine failure speed-V1 definite criterion for decision
Slower than V1 the pilot aborts the takeoff to stop in the event of an engine failure
If an engine fails faster than V1 the pilot must continue the takeoff on remaining engines

7. Balanced Field
V2 is the distance required to stop is exactly the same as that required to reach takeoff speed
Balanced field length is the overall runway distance up to the point of stopping
Figure 5-22 p. 143

8. Landing
Landing in two parts- landing distance & roll distance from touchdown to stop
Touchdown at 15% above stall is appropriate for modern aircraft.
Deceleration is negative acceleration
Most effective braking only reduced roll 10% than with no braking

9. Landing Conditions Runway surface L/D ratio Wind Runway slope
Altitude (pressure & temperature)
Weight

10. Jet Aircraft Performance
Jet-propelled aircraft produce thrust directly from the engine.
Figure 5-23 p. 146
Plot of thrust available and thrust required
The maximum velocity occurs at the intersection of these curves (like power curve)

11. Range & Endurance
Because fuel consumption is proportional is to thrust, the minimum fuel consumption would occur at the minimum thrust required
Best endurance occurs at the minimum point on the thrust required (drag) curve
Figure 5-24 p. 147

12. L/D Ratio
Maximum L/D ratio gives the maximum performance in the following:
Endurance
Power-off Glide Ratio
Angle of Climb

13. Takeoff Vs -stall speed in takeoff configuration
Vmc –minimum control speed for one engine out
V1 –decision speed for engine out
Vr – rotation speed
Vmu –min. unstick speed were safe flight possible
Vlof – proper liftoff
V2 – takeoff climb speed to be reached 35ft alt.

14. Maneuvering Load factors limits established by the FAA
A load factor is the maneuver force in a particular direction divided by the weight of the aircraft
The load factor is the lift divided by the weight in the vertical direction

15. V-n Diagram
V-n diagram is the aircraft operational envelope that ensures design loads are not exceeded
The diagram is simply a plot of velocity for various load factors
Figure 5-27 p. 151

16. Accelerated Climb
Rate of climb-excess power divided by weight (Specific excess power)
“Specific” denotes some quantity per unit
Figure 5-28 p. 153
Figure 5-29 p. 154
Figure 5-30 p. 155

17. Please take out a sheet of paper Include today’s date & your name
Quiz on Chapter 5
Please take out a sheet of paper
Include today’s date & your name

18. Quiz on chapter 5 Explain balance of field. What is a load factor?
What is the purpose of the V-n diagram?