Characteristics of Stability
What is Stability?
The tendency of an aircraft in flight to remain in straight, level, upright flight and to return to this attitude, if displaced, without corrective action by the pilot.
What is Longitudinal Stability?
Stability around the lateral axis.
What is lateral stability?
Lateral stability is stability around the longitudinal axis.
What is directional stability?
Directional stability is stability around the vertical or normal axis.
What is Static Stability?
The initial tendency of an aircraft to return to its original attitude, if displaced.
What control surface controls yaw?
Vertical (Normal) Axis
What is the dangers of an aft centre of an aircraft?
Stall
How many design features provide lateral stability? Name all of them.
3 design features:
Dihedral, sweepback and keel effect
What is the principle factor influencing directional stability?
Vertical Tail surface or Fin.
What type of stability allows the aircraft to return to its original attitude without any corrective measures?
Positive Stability
Vertical (Normal) Axis
What are the two principle factors that influence longitudinal stability?
1. Horizontal Stabilizer
2. Centre of Gravity
What is another word for negative dihedral?
What is the effects of the fin?
If the airplane yaws away from its course, the airflow strikes the fin from the side, forcing it back into position.
Name all the types of stability.
Dynamic, Static, Positive, Neutral and Negative
This axis runs the length of the aircraft from the tip of the nose to the end of the empennage. The movement around the axis is roll. What axis am I?
Longitudinal Axis
Where is the horizontal stabilizer located on the aircraft and what is its function?
The horizontal stabilizer is located at the tail end of the aircraft. When the nose of the aircraft is pushed up, this will force the tail down.
When an aircraft with sweepback is forced into a slipping motion, what happens to the down going wing?
It will meet the airflow at a right angle.
When will the effects of the fin only work?
It will only work if the side area of the aircraft is greater aft of the centre of gravity than the are forward of the centre of gravity.
An aircraft will remain in the new attitude of flight after being displaced, neither returning to its original attitude, nor continuing to move away. What type of stability is this?
Neutral Stability
Explain the three axes and their three control surface.
Longitudinal Axis - Roll
Lateral Axis - Pitch
Vertical (Normal) Axis - Yaw
When the centre of gravity is too far forward, what does it produce? Explain what the pilot would have to do.
What does the keel effect do?
When a wing is forced up by a disturbance, the fuselage acts like a pendulum swinging the aircraft back into position.
What tendency does airplanes always fly head-on into?
Relative Airflow