Principles of FlightLesson 2 – Stability and Control

Stalling

Principles of FlightStability and Control

3 aircraft axes

Why do we want stability?

Longitudinal Stability

• Response to bumps• Response to aircraft not being

trimmed correctly

Lateral Stability

• Response to bumps that lift one wing only

Lateral Stability

Lateral Stability

Directional Stability

• Response to side forces – e.g crosswinds

Pilot Controls

• Easiest way to show you is…..

FLIGHT SIM!

How can we make it easier for the pilot?

• Constantly having to adjust the controls is tiring

• The balance of the plane is always changing due to the weather, weight changes and power settings

• To make life easier for the pilots, the thoughtful designers add Trim Tabs

Trim Tabs

Trim Tabs

Other control surfaces

• Flaps - revision

Flaps

• Flaps can extend to different positions– 0, 30, 60, 90 typical

• Flaps greatly increase lift with not much drag penalty up to around 60°

• From 60° to 90° the drag shoots up• To maintain speed, the pilot lowers

the nose – giving a better view of the runway

Flaps

Flaps

Slats

Flaps and Slats working together

Principles of FlightStalling

Stalling

• What is a stall?• Why does a stall occur?• What affects the speed at which the

stall occurs

What we learnt last week• Increase in AoA increase lift

What we learnt last week• Lift increase with AofA until it stalls

Things that affect the stall - weight

Things that affect the stall – ‘g’

Things that affect the stall – angle of bank

This is what happens!

Things that affect the stall – power

Things that affect the stall – flaps

Things that affect the stall – other things!

• Ice – build up changes the shape of the wing and can greatly increase the stall speed

• Wing damage – damage can disrupt airflow and increase stalling speed