1. Civil jet aircraft performance

2. Four forces of flight Newton’s second law
Resulting force perpendicular to the flight path
Net thrust from the engines
α angle of attack
V velocity
resulting force parallell to the flight path
Newton’s second law

3. Aerodynamic equations
L=Lift = q·S·CL [N]
D=Drag = q·S·CD [N]
q = dynamic pressure [N/m²]
S = reference wing area [m²]
CL = coefficient of lift CL = f(α,Re,M)
CD = coefficient of drag CD = f(α,Re,M)

4. Reference wing area
The area is considered to extend without interruption
through the fuselage and is usually denoted S.

5. Lift versus angle of attack

7. The ISA Atmosphere
From lecture 5

8. Equations

9. Lift equation

10. Drag equation

11. Drag polar

12. High speed drag polar

13. A flight consists of: Taxi Take off Climb Cruise Descent
Approach and landing
Diversion to alternate airport?

14. Cruise
For an airplane to be in level, unaccelerated flight, thrust and drag
must be equal and opposite, and the lift and weight must be equal and
opposite according to the laws of motion, i.e.
Lift = Weight = mg
Thrust = Drag

15. Range

16. Range

17. Breguet range equation
For a preliminary performance analysis is the range equation usually simplified. If we assume flight at constant altitude, M, SFC and L/D the range equation becomes
which is frequently called the Breguet range equation

18. Breguet range equation
The Breuget range equation is written directly in terms of SFC. Clearly maximum range for a jetaircraft is not dictated by maximum L/D, but rather the maximum value of the product M(L/D) or V(L/D).

19. Breuget range equation
From the simplified range equation, maximum range is obtained from
Flight at maximum
Low SFC
High altitude, low ρ
Carrying a lot of fuel

20. Range

21. Endurance Endurance is the amout of time that an
aircraft can stay in the air on one given load of fuel

22. Endurance