Aerodynamik KAP 10+11+(12) Stability & controls Flashcards
What happens to controllability when stability increases ?
Decreases
When and aircraft is in equilibrium the sum of all forces and moments are ___ about the ____
Zero CG
Why do we use control imputs ? (relation to stability)
To overcome the aircrafts stability
What is the general difference between static and dynamic stability ?
Static: Immediate respons when displaced from equilibrium
Dynamic Respons over time
Both static and dynamic stability have 3 categories - what are those ?
Positive - neutral - negative (instability)
What happens when an object is
Positive - neutral - negative
static stabile ?
Positive = ∪ Falls back in the bowl
Neural = — Stays where it is
Negative = ∩ Continues falling over the edge
*Can be more of less stable : The higher the bowl - the more stable - the more energy needed
What happens when an object is
Positive - neutral - negative
dynamic stabile ?
Positive : Falls back in the bowl
Neutral : Keeps swinging in up and down the bowl with the same fluctuation
Negative : Self-reinforcing - the swing becomes more and more
Planes approved by the EASA HAS TO BE ___ ? (stability)
Static stabile
Longitudinal static stability
The distance between CG & AC
The larger distance the ____ stabile the plane is
the less stabile the plane is
How do we maintain equilibrium ?
Continuous pilot input or trim
Where is the AC on a
symmetrical section ?
Asymmetrical section
25% of chord
23-27% chord
A ___ CG increases static stability
Forward
What is load limit ?
The maximum load to be experienced in service
What is ultimate load ?
The FAILING load of the structure
What is the factor of safety ?
Ratio : Ultimate load to the limit load
What is the load factor in level flight. ?
1 ( Lift = weight )
The load factor is the ratio of ____ to _____
Lift to weight
What is the limit load factor based on ?
The maximum take-off weight
What is the safety factor (load factor) for aeroplanes ?
1.5 (If it can pull 6G it actually can pull 9G at which it fails)
What is displayed on the maneuvering envelope ?
Load factor vs. IAS
Below which speed limit is it only possible to stall the aircraft (not distort/fail)
Va
Does weight have an effect on Va ?
Yes - higher Va
(Heavy = stall early = fly faster)
What is Vne determined by ?
Flutter
Below which speed can full elevator deflection be made without exceeding the limit load factor ?
Va
The planes axis all go through
The CG
Lateral stability is around the ____ axis
Roll
Longitudinal stability is around the ____ axis
Pitch
Directional stability is around the ____ axis
Yaw
What happens to the dist. between CP & AC when lift increases ?
Decreases
High mounted wing increases ___ stability
Lateral static stability
Longitudinal stability increases with:
- ^ distance CG & Tailplane
- Forward CG
Which is a major factor to longitudinal stability ?
The tailplane
CG max. forward / CG max. rear of neutral point
What happens ?
Forward: Maximum longitudinal stability
Rear: Weakest acceptable stability
When CG is moved forward - Static longitudinal stability ____
Increases
Stability __ with altitude
Decreases
