Basic Definitions
Longitudinal Stability
Lateral/Directional Stability
Design & Analysis
Advanced Concepts
100

This type of stability describes an aircraft’s initial response to a disturbance.

What is static stability?

100

This wing design feature (e.g., upward angle) enhances lateral stability.

What is dihedral angle?

100

This vertical tail parameter improves directional stability.

What is fin area?

100

This term describes the distance between the CG and neutral point normalized by MAC.

What is static margin?

100

This FAA requirement ensures general aviation aircraft have positive static stability.

What is CFR Part 23 (or 25) airworthiness standard?

200

A positive slope on the C curve indicates this dangerous condition.

What is static instability?

200

The fuselage typically has this effect on longitudinal static stability.

What is destabilizing?

200

Swept wings create this rolling effect when yawed, aiding lateral stability.

What is dihedral effect?

200

A canard-configured aircraft must carefully balance this to avoid excessive pitch sensitivity.

What is static margin or neutral point position?

200

A statically unstable fighter aircraft uses this system to maintain controllability.

What is fly-by-wire with artificial stability?

300

This derivative Cmα must be negative for stable flight.

What is pitching moment coefficient slope?

300

This angle between wing and tail chord lines affects pitch stability.

What is decalage angle?

300

A negative C means the aircraft lacks this stability.

What is directional static stability?

300

This phenomenon reduces static stability when a T-tail experiences downwash from stalled wings.

What is deep stall?

300

This non-dimensional parameter (∂Cm/∂CL) defines neutral point location.

What is the static margin (in terms of CL)?

400

Moving the CG behind this point causes irreversible pitch instability.

What is the neutral point?

400

If CLα rises but C weakens, this stability is lost.

What is longitudinal static stability?

400

Winglets can enhance stability by mimicking this geometric feature.

What is dihedral?

400

In spiral divergence, this type of static stability is insufficient to counter adverse yaw-roll coupling.

What is directional stability?

400

If Cm0 is too positive, the aircraft may exhibit this trim condition at low speed.

What is a nose-up pitch tendency (or excessive trim drag)?

500

This design feature of a horizontal tail increases static stability.

What is the tail volume coefficient (VH)?

500

A statically stable aircraft produces this type of moment after a disturbance.

What is a restoring moment?

500

This FAA regulation mandates positive static stability for civilian aircraft.

What is CFR Part 23?

500

This analytical method uses the sign of C to predict static stability.

What is the stability criterion (or Routh-Hurwitz for dynamics)?

500

This design trade-off reduces static stability to improve maneuverability in combat aircraft.

What is relaxed static stability?

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