4.Stability & Control

Define Stability

Tendency of the p[lane to return to its original position after being moved/disturbed

Define Controlability

Ease of which a pilot can manoeuvre the plane

What’s Positive Static Stability

Plane returning to its original position after disturbance

What’s Neutral Static Stability

Plane Remianing in disturbed state

What’s Negative static Stability

Plane deviates even further after disturbance

Whats Positive dynamic stabilty

After disturbance is gone oscillations dampen to zero

Whats neutral dynamic stability

After disturbance is gone oscilations remain the same

Whats Negative dynamic stability

After disturbance is removed oscillations worsen

Can we have Negative static & Positive dynamic?

No, because dynamic stability doesn’t exist without positive static

Longitudinal stability: Axis, Length, Tendency,

Lateral Axis, Nose to tailplane, Return to original AoA

Directional stability: Axis, Tendency,

Normal Axis, allows plane to weathercock into crosswind/sideslip

Lateral stability: Axis, Length, Tendency,

Longitudinal axis, Wingtip to wingtip, Lower wing having larger AoA returns wings level

What’s Dihedral, whats it do?

Wings leveled up, improves lateral stability

Whats anhedral, whats it do

Wings angled down, to overcome excess stability

Whe does spiral instability occur?

Weak lateral, strong directional stability

When does the Dutch roll occur?

Strong Lateral, weak directional stability

What do spoilers do?

Spoils lift/increases drag, helps steepen descent and increased weight on wheels

Whats the purpose of vortex generators?

Delyas the seperation point by mixing turbulent air → Reenergises the boundary layer

What do vortex generators do to lift & drag?

Increase more lift than drag

Wheb are vortex generators most advantageous

Climbs & Takeoff

What dos the Horn Balance do in neutral & and in action?

In neutral does nothing. Protrudes into the airflow to provide aerodynamic balance

Whats aerodynamic Balance?

Term use to reduce stick force

What is a balance tab? Whats it do?

Tab moving in the opposite direction of the elevator. Reduces stick force → creating a mall force to hold it up/down

What is an Anti balance tabe? Whars it do?

Tab moving in the same direciton as the elevator. Increasing stick force

What is Mass Balancing? Whats it do?

An added weight to move CoG closer to hinge line. Prevents flutter