Performance I

Question 1

What is the key element for determining an aircraft’s performance?

Answer 1

The drag polar.

Question 2

CD stands for (note the capital D)?

Answer 2

The drag coefficient for the entire aircraft.

Question 3

C_D_0 stands for?

Answer 3

The parasite drag coefficient for the aircraft.

Question 4

The Oswald efficiency factor is represented using the symbol ___.

Answer 4

e

Question 5

For basic performance, lift is considered to be _______.

Answer 5

Perpendicular to the flight path direction and equal and opposite to the weight.

Question 6

For basic performance, drag is considered to be _____ to the flight path direction.

Answer 6

Parallel

Question 7

True or False
For an aircraft in flight, the thrust is often inclined with respect to the flight path although the angle is usually small.

Answer 7

True

Question 8

The angle between the horizontal plane and the flight path is given the symbol ____.

Answer 8

theta

Question 9

True or False
The flight path is drawn in a straight line, however, the AC is generally traveling in a curved path (especially when viewed from a distance).

Answer 9

True

Question 10

In the most basic sense, all flight is ______ as opposed to straight.

Answer 10

Curvilinear

Question 11

The case where the acceleration of the aircraft is equal to zero is referred to as _________.

Answer 11

Static performance.

Question 12

For completely level flight, the angle between the horizontal and the flight path is _______.

Answer 12

Zero

Question 13

True or False
In steady level flight with no acceleration or disturbances, T = D and L = W.

Answer 13

True

Question 14

Thrust required varies proportionally with _______ and inversely with ______.

Answer 14

The drag coefficient times the weight
The lift coefficient

T = (CD*W)/CL = W/(CL/CD)

Question 15

Thrust required varies inversely with the _____ ratio.

Answer 15

Lift to Drag

Question 16

The thrust required is directly proportional to the ____ ratio.

Answer 16

Drag to lift (D/L)

Note: T = 1/(L/D) = D/L

Question 17

Since Thrust required varies ____ with the lift to drag ratio, the minimum thrust required will occur when ______.

Answer 17

Inversely
The aircraft is flying at a velocity where the L/D ratio is at a maximum

Question 18

True or False
The L/D ratio is a measure of the structural efficiency of the AC.

Answer 18

False, its a measure of the aerodynamic efficiency.

Question 19

On the velocity vs thrust required curve, a low speed corresponds to what five aerodynamic characteristics?

Answer 19

1. High angle of attack
2. High CL
3. High CD_i (induced drag)
4. Low q_infinity
5. Low CD_0

Question 20

On the velocity vs thrust required curve, a high-speed corresponds to what five general aerodynamic characteristics?

Answer 20

1. Low angle of attack
2. Low C_L
3. High q_infinity
4. High C_D_0
5. Low C_D_i

Question 21

Induced thrust decreases with ________.

Answer 21

Increasing velocity and vice versa.

Note: Induced thrust required is proportional to inverse velocity squared.

Question 22

Parasite thrust increases with ________.

Answer 22

Increasing velocity and vice versa.

Question 23

Minimum thrust required occurs where ____.

Answer 23

The airspeed at which the lift to drag ratio is at a maximum.

Question 24

At (L/D) max, the airframe’s induced drag is equal to ______.

Answer 24

The parasite drag.

CD_0 = CD_i

Question 25

Thrust required is an ______ associated phnomenon.

Answer 25

Airframe

Question 26

Thrust available is an ______ associated phenomenon.

Answer 26

Engine

Question 27

For a propeller driven aircraft, thrust at a zero velocity is at a ____________.

Answer 27

Maximum

Question 28

For a propeller-driven aircraft, thrust varies as forward speed changes in accordance with ______.

Answer 28

The efficiency of the propeller (\Nu_prop)

Question 29

For a reaction jet engine, the thrust _____ slightly with forward speed due to _______.

Answer 29

Increases Inlet pressure recovery

Question 30

If the thrust increases to the maximum amount available, the aircraft's speed is ______.

Answer 30

Fixed

Question 31

The intersection of what two curves defines the maximum aircraft speed?

Answer 31

The Tr (thrust required) and the Ta (thrust available) curve.

Question 32

For gliding flight, the descent angle is strictly a function of ______.

Answer 32

The lift to drag ratio.

Question 33

At low speeds, C_D_0 includes _____ and _____.

Answer 33

Skin friction pressure drag Pamadi, Pg. 72

Question 34

What is power required?

Answer 34

The power required is the power necessary to overcome the aerodynamic drag of the airplane. Pamadi, Pg. 72

Question 35

What is thrust required?

Answer 35

The thrust necessary to balance the aerodynamic drag of the aircraft. Pamadi, Pg. 72

Question 36

For a given altitude, the power developed by a piston engine is virtually constant with _______.

Answer 36

Flight Velocity Pamadi, Pg. 73

Question 37

Power developed by a piston engine decreases with an increase in altitude because of _______.

Answer 37

The decrease in density. Pamadi, Pg. 73

Question 38

What is required for a piston aircraft's propulsive efficiency to be assumed constant over the operating range?

Answer 38

The aircraft must be equipped with a variable pitch, constant speed prop. Pamadi, Pg. 73

Question 39

For gliding flight, the flattest glide occurs when ____.

Answer 39

The glider flies at (CL/CD) max or the minimum drag per unit weight. Pamadi, Pg. 80

Question 40

What CL/CD condition is required for max range in a glider.

Answer 40

Max CL/CD Pamadi, Pg. 80

Question 41

For a glider, the rate of sink is at a minimum when _____.

Answer 41

CL^(3/2) / CD is maximum. Pamadi, Pg. 81

Question 42

For a glider, the maximum endurance occurs when ______.

Answer 42

CL^(3/2) / CD is maximum. Pamadi, Pg. 84

Question 43

For a glider, endurance is _______ when sink rate is minimum.

Answer 43

Maximum Pamadi, Pg. 84