081.03 Stall, Mach tuck, and upset prevention and recovery

Question 1

Define ‘V_S’. It is (lower/higher) than V_S1g.

Answer 1

Minimum calibrated airspeed at which an aeroplane remains controllable, but does not require horizontal flight. Therefore it is lower than V_S1g.

Question 2

Define ‘V_S1’.

Answer 2

Stall speed or the minimum steady flight speed for a specified configuration (which may be clean configuration)

Question 3

Define ‘V_S0’.

Answer 3

Stall speed for landing configuration

Question 4

Define ‘V_SR’.

Answer 4

Reference stall speed. Usually equal to V_S1g.

Question 5

Define ‘V_S1g’.

Answer 5

Minimum calibrated airspeed at which an aeroplane is able to maintain steady horizontal flight (L=W)

Question 6

Stall speed V_S1g is determined with the CG as far (forward/backward) as possible.

Answer 6

Stall speed V_S1g is determined with the CG as far (forward) as possible.

Question 7

Behind the transition point in a boundary layer, the mean speed (increases/decreases) and the friction drag (increases/decreases).

Answer 7

Behind the transition point in a boundary layer, the mean speed (increases) and the friction drag (increases)​.

Question 8

Compared to the laminar boundary layer, a turbulent boundary layer:

• is (thicker/thinner)
• gives a (lower/higher) skin friction
• has (more/less) kinetic energy
• will seperate (more/less) easily

Answer 8

Compared to the laminar boundary layer, a turbulent boundary layer:

• is (thicker)
• gives a (higher) skin friction
• has (more) kinetic energy
• will seperate (less) easily

Question 9

Stall speed (IAS) (remains constant/increases/decreases) at lower altitudes but (remains constant/increases/decreases) at higher altitudes due to compressibiltiy effects.

Answer 9

Stall speed (IAS) (remains constant) at lower altitudes but (increases) at higher altitudes due to compressibiltiy effects.

- EAS remains contstant until supersonic -

Question 10

Centre of pressure moves (forward/aft) on a swept back wing as angle of attack approaches and exceeds the critical AoA.

Answer 10

Centre of pressure moves (forward) on a swept back wing as angle of attack approaches and exceeds the critical AoA.

Question 11

Centre of pressure moves (forward/aft) on a straight wing as angle of attack approaches and exceeds the critical AoA.

Answer 11

Centre of pressure moves (aft) on a straight wing as angle of attack approaches and exceeds the critical AoA.

Question 12

Minimum control speeds are determined with the CG at the (forward/aft) limit.

Answer 12

Minimum control speeds are determined with the CG at the (aft) limit.

Question 13

Type of stall that has the largest associated AoA is (accelerated/high speed/low speed/deep) stall.

Answer 13

Type of stall that has the largest associated AoA is (deep) stall.

Question 14

The main purpose of a boundary layer fence on a swept wing is to improve (high/low) speed handling characteristics.

Answer 14

The main purpose of a boundary layer fence on a swept wing is to improve (low) speed handling characteristics.

Question 15

(Stall speed/α_crit) remains unchanged regardless of gross weight.

Answer 15

(α_crit) remains unchanged regardless of gross weight.

Question 16

Describe ‘deterrent buffet’ and why it can be considered a stall limit.

Answer 16

A buffet so strong that any pilot will feel he needs to leave these buffet conditions. It can be considered a stall limit because the buffet is so strong that pulling any further will cause the aircraft to enter an actual stall.

New LO. Source: https://safetyfirst.airbus.com/app/themes/mh_newsdesk/pdf/safety_first_21.pdf

Question 17

State in how the following will change the buffet free range change. Change in:

• Increase in altitude
• Increase in speed
• Increase in mass
• Increase in load factor
• Push-/pull-over manouvre

Answer 17

State in which of the following changes will the buffet free range change. Change in:

• Increase in altitude → buffet free range decreases
• Increase in speed → no change
• Increase in mass → buffet free range decreases
• Increase in load factor → buffet free range decreases
• Push-/pull-over manouvre → buffet free range increases (load factor < 1)

Question 18

A stall can occur at any airspeed, attitude or altitude because (…).

Answer 18

A stall can occur at any airspeed, attitude or altitude because (stall solely depends on angle of attack).