PoF - Chapter 10 Stability

The position of the Centre of Gravity when the tail moment = wing moment is:

• aerodynamic centre

• neutral point

• centre of pressure

• aft CG limit

Static margin is the distance between:

• the leading edge and trailing edge

• forward CG and aft CG limit

• neutral point and aft CG limit

• neutral point and actual aircraft CG

Minimum Static Stability Margin:

• affects lateral stability

• is the distance between forward CG limit and neutral point

• is the distance between neutral point and aerodynamic centre

• is the distance between neutral point and aft CG limit

Which of the following statements is correct?

• Decreased static stability decreases controllability.

• Increased static stability decreases controllability.

• Static stability does not affect controllability.

• Increased static stability increases controllability.

For longitudinal static stability:

• the tailplane has a bigger angle of incidence compared to the wings

• the tailplane has a smaller wing incidence compared to the wings

• the tailplane has a bigger angle of attack compared to the wings

• the tailplane has the same angle of incidence compared to the wings.

Decrease downwash angle:

• Increases lateral stability

• Increases directional stability

• Increases static longitudinal stability

• Decreases static longitudinal stability

An aircraft with CG near the forward limit will be:

• longitudinally unstable

• laterally unstable

• dynamically neutral

• hard to control

A low-wing twin-engine jet with turbine engines mounted on the underside of each wing will:

• pitch up when thrust is increased

• pitch down when thrust is increased

• show no changes in pitch when thrust is increased

• pitch down then up when thrust is increased

For an aircraft to be dynamically stable:

• it must be statically stable

• it must be statically unstable

• it must be statically neutral

• it must be dynamically neutral

Too much static lateral stability could result in:

• Spiral instability

• Dutch Roll

• Spin

• Stall