Theory of flight Qs Flashcards
Name the secondary flight controls?
Flaps, Slats, THS, Spoilers
Which axis does the Rudder act on?
Vertical Axis
On which axis does the Elevator act on?
Lateral Axis
On which axis does the Aileron act on?
Longitudinal
What is a flight control trim system used for?
To maintain an equilibrium of an aircraft during flight without using a steering force
Name some types of high lift devices used on a modern jet aircraft?
Slots, Slats, Flaps
Separation of the boundary layer causes the wing to stall, name some boundary layer control devices?
Sweeping back wings, Vortex Generators, Fences or Saw tooth/dog tooth
What is the function of a servo tab?
A tab on the flight control surface assists to help move the control surface
What is the function of a trim tab?
A trim tab will be moved to crease an aerodynamic force that will move the control surface and hold it deflected.
How does a balance tab work?
The control rod for a surface is attached to the underside of the tab and the underside of the fixed wing.
How does a Spring Tab work?
When control forces are high the spring will compress and this moves a rod connected to the tab to reduce the overall force on the surface.
What is the purpose of mass balancing?
To prevent control surface flutter
How is flutter prevented?
Using mass balancing where weights are added in front of the hinge line to bring the center of gravity closer to the hinge.
Speed of sound is affected by the ……………… of the air
Temperature
What is the critical Mach number?
This is the number where the first indication of sonic flow (normal shockwave) forms somewhere on the wing
The speed range below Mach 0.75 is?
Subsonic
The speed range between Mach 0.75 - 1.20 is?
Transonic
The speed range between Mach 1.20 - 5 is?
Supersonic
The speed range greater than Mach 5 is?
Hypersonic
In low speed flight air is considered to be?
Incompressible
In high speed flight air is considered to be?
Compressible
What are the 3 types of pressure waves?
Normal an Oblique shockwaves and expansion waves
An oblique shockwave is?
Supersonic air striking a sharp edged airfoil that is forced to turn.
Increasing the critical Mach number by effectively decreasing the thickness ratio of the wing is?
Sweepback on the wings
Explain the definition ‘rotor blade angle’?
The angle between the rotor blade chord and the reference plane.
Explain the definition ‘rotor angle of attack’?
The angle between the chord line of the airfoil and the relative wind
What is the feathering axis?
The axis on which the pitch is changed
What is the collective used for?
To raise or lower ALL the aircraft by changing the pitch
What is the cyclic used for?
To raise or lower some blades and used in a turn.
What are the foot pedals of a helicopter used for?
To steer the helicopter by counteracting or assisting the torque
