Basic Definitions
This type of stability describes an aircraft’s initial response to a disturbance.
What is static stability?
This wing design feature (e.g., upward angle) enhances lateral stability.
What is dihedral angle?
This vertical tail parameter improves directional stability.
What is fin area?
This term describes the distance between the CG and neutral point normalized by MAC.
What is static margin?
This FAA requirement ensures general aviation aircraft have positive static stability.
What is CFR Part 23 (or 25) airworthiness standard?
A positive slope on the Cmα curve indicates this dangerous condition.
What is static instability?
The fuselage typically has this effect on longitudinal static stability.
What is destabilizing?
Swept wings create this rolling effect when yawed, aiding lateral stability.
What is dihedral effect?
A canard-configured aircraft must carefully balance this to avoid excessive pitch sensitivity.
What is static margin or neutral point position?
A statically unstable fighter aircraft uses this system to maintain controllability.
What is fly-by-wire with artificial stability?
This derivative Cmα must be negative for stable flight.
What is pitching moment coefficient slope?
This angle between wing and tail chord lines affects pitch stability.
What is decalage angle?
A negative Cnβ means the aircraft lacks this stability.
What is directional static stability?
This phenomenon reduces static stability when a T-tail experiences downwash from stalled wings.
What is deep stall?
This non-dimensional parameter (∂Cm/∂CL) defines neutral point location.
What is the static margin (in terms of CL)?
Moving the CG behind this point causes irreversible pitch instability.
What is the neutral point?
If CLα rises but Cmα weakens, this stability is lost.
What is longitudinal static stability?
Winglets can enhance stability by mimicking this geometric feature.
What is dihedral?
In spiral divergence, this type of static stability is insufficient to counter adverse yaw-roll coupling.
What is directional stability?
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)?
This design feature of a horizontal tail increases static stability.
What is the tail volume coefficient (VH)?
A statically stable aircraft produces this type of moment after a disturbance.
What is a restoring moment?
This FAA regulation mandates positive static stability for civilian aircraft.
What is CFR Part 23?
This analytical method uses the sign of Cmα to predict static stability.
What is the stability criterion (or Routh-Hurwitz for dynamics)?
This design trade-off reduces static stability to improve maneuverability in combat aircraft.
What is relaxed static stability?