Describe the characteristics of the upright spin, and explain:

(a) the instrument indications which confirm the fact and direction of a spin;

(b) the difference between the spin and spiral dive;

(c) the standard recovery technique.

Once the aircraft has made approximately one turn it will be established in a spin.

The aircraft will be yawing, rolling and probably pitching too.

(a) Instrument indications

• The airspeed will be low
• The altitude will be reducing rapidly
• The ball will be indicating the direction of the spin

(b) There is a difference between the spin and the spiral dive.

In the spiral dive the airspeed will be steadily increasing; a spiral dive is really just a steep descending turn 

In the spin the airspeed is low 

(c) The standard recovery technique for a spin is

Power, reduced to idle

Ailerons neutral

Rudder, full opposite rudder against the direction of spin

Elevators, Check well forward to break the stall. 

Once airspeed is increasing roll the wings level and recover to level flight

DO NOT roll wings level and pull out of the dive at the same time. This will cause rolling G which may damage the aircraft. these two actions must be done separately.

                                        

                           

22.16.22

Explain the process of autorotation (leading to the spin).

Autorotation is when the aircraft starts rolling in an uncontrolled way. This is the precursor to the spin.

When the aircraft stalls, one wing will stall before the other and will end up more deeply stalled, even though both of the wings are stalled. This will cause the aircraft to roll. At this point the further effect will take place and the aircraft will start to yaw. This is self-sustaining and will get worse and worse. At this point because the aircraft has stalled the nose will also pitch down. The aircraft will be pitching, rolling and yawing all at the same time.

This will quickly develop into the spin.

22.16.20

Describe the standard technique for recovery:

(a) from a stall which has resulted in a wing-drop;

(b) at the onset of the stall.

(a) When an aircraft has stalled and the wing has dropped the standard recovery is as follows

1.     Check forward to reduce the angle of attack
2.     ensure the ailerons are centralised
3.     Stop the yaw with rudder
4.     Apply full power
5.     once the aircraft has some speed raise then set nose to the climb attitude

(b) At the onset of the stall  

1. Check forward to reduce angle of attack
2. Apply full power
3. control any resulting yaw with rudder
4. set the nose to the flying attitude as soon as the aircraft has accelerated

22.16.18

Explain the caution against using aileron near or at the stalling angle

Using aileron at or near the stall will generally aggravate any wing drop tendency. The aircraft can actually enter autorotation and eventually a spin.

This is because of the increase in drag caused by the downing aileron compared to the upgoing aileron.

22.16.16

Explain the design measures taken to reduce the tendency for wing-drop.

There are several measures that can be taken to reduce the tendency for a wing drop.

The one used most often is washout. The angle of incidence is reduced towards the tip. This will cause the inboard section of the wing to stall first, minimising wing drop

Another method being used is to split the wing in two and have the outer section of the wing at a different angle of attack, the effect is the same except aileron control will be retained for longer.

The other common method of reducing the tendency of wing drop is that the aircraft can be fitted with stall strips on the inboard leading edges. This will cause the inboard section to stall first.

22.16.14

Describe the conditions which encourage a wing-drop at the stall.

Adding power and flap will destabilise the stall, possibly causing a wing drop. 

Yawing and/or rolling the aircraft will also cause a wing drop stall.

22.16.12

Describe how the following factors affect stalling speed:

(a) aircraft weight;

(b) load factor;

(c) power;

(d) altitude;

(e) the use of flaps and slats;

(f) contamination of the wing surfaces.

(a) As the weight of the aircraft increases the stall speed will increase

(b) An increase in load factor will increase the stall speed

(c) Use of power will lower the stall speed

(d) Altitude has no effect on the stall speed in terms of IAS it only affects TAS

(e) Use of flaps and slats will lower the stall speed

(f) Contamination of the wing surfaces will cause a higher stall speed. Damage to the leading edge of the wing will usually have a similar effect

22.16.10

Explain the standard recovery from the stalled condition.

Recovery from a stalled condition is as follows

1. Full power

2. Check forward to break the stall

3. Once the aircraft is unstalled and the airspeed is increasing raise the nose to the climb attitude

22.16.8

Describe the changes in the airflow over the wing, movement of the CP, and aircraft attitude as the point of stall is reached.

When the aircraft reaches the point of stall the air will no longer be able to flow over the wing

         

The centre of pressure moves forward as angle of attack increases until the point of stall. At that point the centre of pressure moves rapidly aft. 

The attitude of the aircraft at the stall will be a high nose attitude. Once the aircraft has stalled the nose will pitch down.

22.16.6

Describe typical symptoms and other indications of the approach to the stall.

The typical symptoms of a stall are;

• A high nose attitude
• A low airspeed
• The flight controls will be sloppy and a lot of movement will be required
• The elevator will be almost if not all the way back, nose up
• The aircraft may experience buffeting, depending on the configuration
• The stall warning will be sounding (if fitted)
• It will be quiet in the aircraft