Flight Controls | Aeroelasticity Flashcards
Aeroelasticity is the ___, or ___
- interaction between aerodynamic loads and elastic strain on the airframe
- Whether a component bends or twists under the loads imposed by flight
A material is said to be wholly elastic if ___
The strain caused by a stress goes away when the stress is removed
A material is said to be plastic when ___
The strain caused by a stress does not go away when removed
The new position of a plastic material following an applied stress is called the ___
permanent set
___ wings and surfaces with ___ aspect ratios will suffer the most from aeroelastic distortion
Swept high
Flutter is a ___
divergent oscillatory motion of a control surface from the interaction of aerodynamic and inertia forces, and stiffness of the structure
Flexural flutter is caused by ___
CG of a control surface being offset from the control hinge line, with flex as lift changes.
Flexural flutter can be prevented by ___
introducing mass balances in front of the torsion axis to better place the CG
Torsional flutter is aka ___ ___
cyclic deformation
Torsional flutter will occur when ___
increased lift on a control surface causes a turning moment about a torsional axis
Buffeting is ___
high-frequency instabiliy caused by airflow separation of shock wave oscillations from one object striking another
During divergence, elastic twist suddenly becomes ___
infinite
Fly-by-wire systems use ___ transmitted over ___ that connect to ___ at the control surfaces
electrical systems, electrical cables, hydraulic actuators
With fly by wire, the flight controls operate ___ in the shape of ____ which produce command signals based on the voltages that are proportional to the movement of the control
transducers, Rotary Variable Differential Transformers
The benefits of Fly By Wire are ___
- Save weight
- Reduce maintenance
- Save space
Fly by wire redundency is achieved by having ___ or ___
multiple pathways for signals, or multiple computers for the same task
Flight control software is certified to the highest level: _
A
Software levels are designed according to the ___
effects of a software failure
Reversible flight controls must have a ___ which are essential for manual controls
gust lock
On a cable operated system, the gust lock will stop the control column from moving if the controls do not have ___ ___
servo tabs
Primary stops are fitted to ___
control surfaces
Secondary stops are fitted to ___
flight controls
TOCWS is ___
Take Off Configuration Warning System
Aileron upset is a system that biases the ailerons ___
up to move the wing’s centre of pressure inwards to reduce wing bending
TOCWS will be activated as a result of:
- Control locks not removed
- Powered flying controls INOP
- Feel simulators INOP
- Flap settings incorrect
- Slat settings incorrect
- Trim outside of limits
- Aileron upset armed but not applied
- Speedbrakes/spoilers not in
- Doors not locked
