Aerodynamic Forces In Flight Manoeuvres

Question 1

What are the four forces that act on the A/C in straight and level flight?

Answer 1

• Lift
• Drag
• Thrust
• Weight

Question 2

What occurs when the landing gear are lowered on the A/C?

Answer 2

Total drag is increased, which causes speed to decrease, until point where thrust and drag are in equilibrium again.

Question 3

What occurs in straight and level flight when the flaps are lowered?

Answer 3

• Drag will increase to decrease the speed of the A/C
• An initial increase in lift will occur which must be countered by the pilot to prevent the aircraft climbing. Angle of attack must be reduced.

Question 4

What is one of the fundamental formula for performance?

Answer 4

Power + Attitude = Performance

Question 5

What are the forces on the aircraft in a straight and level turn? Draw a diagram.

Answer 5

1) Total Lift
2) Vertical Component of Lift
3) Centripetal force
4) Centrifugal force
5) Resultant Load
6) Weight

Question 6

What control input is required to maintain level flight in a steep turn?

Answer 6

Elevator

Question 7

What is the load factor in a 30 deg banked turn?

Answer 7

1.15

Question 8

What is the load factor in a 60 deg banked turn?

Answer 8

2g

Question 9

What are the various g forces required at various points in the turn?

Answer 9

• At bottom = 4g
• At side = 3G
• At top = 2g

Question 10

What should be done to find a constant loop?

Answer 10

• Speed must constant

- G load will vary according to the point in the loop

Question 11

Describe slipping and skidding?

Answer 11

• Slipping is not enough rudder in the turn

- Skidding is too much rudder in the turn

Question 12

What is the relationship between weight and CFF in a balanced turn?

Answer 12

Weight and centrifugal force are equal with ball in centre

Question 13

What is the relationship between weight and centrifugal force in a slipping turn?

Answer 13

Weight is greater than CFF

Question 14

What is the relationship between weight and centrifugal force in a skidding turn ?

Answer 14

Centrifugal force is greater than weight.

Question 15

What does an aircraft tend to do in a straight and level turn, climbing and descending turn re. banking tendencies?

Answer 15

• In a S&L turn, aircraft will want to bank into the turn
• In a climbing turn, aircraft will tend to overbank into the turn as the upgoing wing follows a steeper spiral path and will therefore have a reduced AoA, and will generate less lift
• In a descending turn, the inner wing follows a steeper downwards spiral path and will tend to roll out of the turn.

Question 16

What is the difference between turn rate and turn radius?

Answer 16

• Turn rate refers to the how quickly the aircraft is changing heading in the turn
• Turn radius refers to how much distance is required for the A/C to change heading in a certain direction.

Question 17

What is the formula for turn radius and ROT?

Answer 17

• Turn radius = KTAS^2 / 11.26*tan(AOB)

- Turn rate = 1091 * Tan (AOB) / KTAS

Question 18

Does speed have a greater effect on turn radius or turn rate?

Answer 18

Turn radius than on turn rate.

Question 19

Do turn rate and turn radius depend on weight?

Answer 19

No

Question 20

What is the relationship between load factor and stall speed?

Answer 20

Stall speed = basic stall speed * sqrt (Load factor).

Question 21

What is a Rate 1 turn?

Answer 21

Turn rate of 3 deg / s

Question 22

What is the useful rule to calculated the AoB required for a rate 1 turn at a given speed?

Answer 22

AoB = TAS (IAS at low altitudes) / 10 + 7

Question 23

What is a maximum rate turn?

Answer 23

A max rate turn is achieved when an aircraft changes direction at the highest possible rate.

Question 24

What is the formula for max rate turn?

Answer 24

Rate of rotation = 0.5 * (S/W) * rho * V * Cl * sin(AoB)

Question 25

What are the perfect requirements for a max rate turn?

Answer 25

• Minimum wing loading
• Maximum air density
• Maximum value of the product of speed, angle of bank and AoA
• Sufficient thrust available to maintain the speed mentioned above, with the lift-dependent drag rise with max values of Cl

Question 26

What can be practically altered to improve the max rate turn?

Answer 26

• Vertical component of thrust, at high AoA
• Combat flaps
• Variable Nozzles

Question 27

Practically, how close to stall speed is a max rate turn?

Answer 27

Close to stall at high g loading.

Question 28

What are the three main factors that determine max rate turn performance?

Answer 28

• Clmax
• g limit
• Max power

Question 29

What speed is the maximum distance between power required and power available?

Answer 29

Max rate of climb (Vy)

Question 30

Where would max angle of climb (Vx) be?

Answer 30

Max difference between thrust required and thrust available.

Question 31

Is lift greater than weight in a climb?

Answer 31

No

Question 32

Is lift greater than weight in a powered descent?

Answer 32

No

Question 33

At what speed will the aircraft glide at?

Answer 33

Min drag speed to maximize L/D ratio

Question 34

What is the effect of weight on glide distance?

Answer 34

Doesn’t have an effect, but the heavier aircraft will glide at a higher speed to get to the optimum AoA to maximum L/D.

Question 35

What will a tailwind/headwind do to glide distance?

Answer 35

• A headwind will reduce glide distance

- A tailwind will increase glide distance.