Airframe limitations Flashcards
Airframe limitations
Airframe limitations including engine operating parameters inform the aircraft operator of the safe working limits of a particular aircraft
It includes speed, weight, G loading and engine power settings required for all phases of flight
Forces on an aircraft in flight
There are four forces
Lift
Weight
Drag
Thrust
Lift
The force that holds an aircraft in the air
Weight
The force that attempts to keep the aircraft on the ground
Thrust
The force that gives an aircraft it’s forward momentum
Drag
Defined as any component of the aerodynamic forces which acts parallel and opposite to the direction of flight
Categories of drag
Zero lift drag or parasitic drag
Lift dependent drag or induced drag
Pitch stability
If the aircraft experiences an upward vertical gust the horizontal stabiliser will have greater lift and then pitch the nose back down
If the aircraft has a case of a downward vertical gust the horizontal stabiliser will have a decreased angle of attack and decreased lift which then pitches the nose back up
Pitch stability versus COG
A forward centre of gravity leads to increased pitched ability and aft movement of the centre of gravity leads to reduced pitch stability
Roll stability
Positive dihedral increases role and is a feature of the most low wing aircraft
If the aircraft rolls, the lower wing has greater lift opposing weight which rolls the aircraft back to level
Yaw Stability
Axe similar to pitched ability except the vertical plane instead of the horizontal plane
If the aircraft yaws the result is the vertical stabiliser and the keel surfaces now produce lift in the opposite direction which restores the aircraft to its original direction
Airspeed limitations
V1= Take off decision speed
Vr= Take off rotate speed
Vs=Stall speed
Vne: Max speed never exceed
G loading
The numerical ratio of any applied force to the gravitational force at the earths surface
Straight and level flight equals 1G
Flight envelope
Found in the flight manual of the specific aircraft
