11.1 Flashcards
Whats the 3 axis on an aircraft and Whats there positions ?
Lateral axis - wing tip to win tip
Longitudinal axis - nose to tail
Vertical axis - bottom of aircraft to top.
Whats the three moments an aircraft has ?
Roll - longitudinal axis
Pitch - lateral axis
Yaw - vertical axis
Whats the three primary flight controls ?
Ailerons
Elevators
Rudder
What’s the two types of control surfaces ?
Primary
Secondary
Whats a stabilator a combination of ?
Stabiliser and elevator.
( found on high speed aircraft to produce rapid manoeuvrability )
( sometimes referd to as a slab tail )
What plane does the variable incidence stabilisers stabilise ?
Longitudinal plane ( lateral axis )
What does a canards configuration influence on the flight controls ?
Greater pitch control
Stability
Stall prevention
Higher angle of attack
Control redundancy
Lift and trim
What reduces the rudder deflection ?
Aircraft speed
( E.G - rudder can rotate 25 degrees maximum on ground but only 5 degrees maximum in the air )
Whats the 3 preventions for adverse yaw ?
Spoilers
Ailerons differential
Frise ailerons
Whats a elevon ?
Control surface for roll ( ailerons ) and pitch ( elevator) is combined.
( found on delta - wing aircraft. )
( used on Concorde )
Whats a ruddervator ?
Used for pitch ( elevator ) control surface and yaw ( rudder ) control surface.
( found on V-shaped tailed aircraft )
What are secondary flight controls used for ?
Increases amount of lift or drag produced by the wing
Whats secondary flight controls are on the leading edge of the wing ?
Slats
Slots
Leading edge flaps ( Krüger )
What secondary flight controls are on the trailing edge of the wing ?
Flaps
Spoilers
Why is a secondary control system used mainly on the takeoff and landing ?
Reduce stall speed when landing
Increase drags when landing
Increase lift when taking off
Whats the difference between a slat and a slot ?
Slots are fixed into position where as slats is a movable surface.
What does slots and slats do to the flow separation ?
They delay it.
Whats the purpose of leading edge flaps ?
Greatly increase wing camber and lift.
( extends camber of wing )
Whats a leading edge droop designed for ?
To improve airflow over wing at high angle of attack.
( increases camber causing increase In lift )
( reduces stalling speeds )
What’s different between leading edge droop and slats ?
Entire leading edge section rotates downwards on a droop rather than than just extending outwards like a slat.
Whats a flaperon a combination of ?
Flaps and ailerons.
Are drag devices primary or secondary flight control surfaces ?
Secondary.
What the three functions of spoilers ?
Flight spoilers ( speed brakes )
Ground spoilers ( lift dumpers )
Roll spoilers.
What does speed brakes do ?
Increase the drag
( THEY DO NOTHING TO THE LIFT )
What danger comes if the tip stalls first on a swept wing aircraft ?
Approaching stall speed gives little to no warning to the pilot and controls may not be operational e.g ailerons ( which are located near the tip )
What’s the purpose of a wing fence ?
Reduces effects of spanwise flow and helps reduce wing tips stalling.
What does a vortex generator do ?
Re - energise slow moving boundary layer.
( Placed ontop of wing. )
Whats the use of a stall wedge ?
Forces root to stall first
( minimises the risk of spinning and allowing maximum aileron control throughout the stall. )
( also gives pilot warning of the stall due to the turbulence created at wing root )
Where are trim tabs located ?
Trailing edge of primary flight controls
( hinged surface )
Is a trim tab primary or secondary flight control ?
Secondary flight control
Whats the purpose of a balance tab ?
Assists commanded movements by changing the camber of control surface.
( when control surface is deflected, the tab moves in opposite direction )
Is a servo tab used for low, high or all speeds ?
All speeds
( tab moves in opposite direction tot he flight controls its attached to )
Explain a spring tab ?
Same as a servo tab but only operates when the force on a control surface reaches a certain value.
What does anti-balance tabs give to. The movement of a control surface ?
Greater resistance.
Whats the difference to horn balance and insert line ?
Horn balance you add a part to the component to balance it an insert you shift the hinge back further to balance two parts either side of it.
Whats the equation for Mach number ?
M = velocity of object (V)
—————————-
Speed of sound (a)
What range of speed is an aircraft in if the Mach number is bellow 0.8 ?
Subsonic
What speed range is an aircraft if the Mach number is from 0.8 to 1.2 ?
Transonic
What range of speed is an aircraft in with a Mach number from 1.2 to 5.0 ?
Supersonic
explain subsonic flight ?
-Aircraft is subsonic when its operating at speeds bellow the speed of sound
-ranges in speeds of Mach 0 - 0.8
-air when subsonic is incompressible
Explain transonic flight ?
-combination of subsonic and supersonic airflow
-forms shock waves ( 0 degrees to airflow )
-poses stability challenges
-
Explain supersonic flight ?
-spans from Mach 1.2 to 5.0 ( anything above Mach 5.0 is considered hypersonic )
-shockwave created over aircraft’s wing during transonic flight moves to the rear ( trailing edge )
-air is compressible
-reduction in coefficient lift and increase in drag
What two regions do shock waves form in ?
Transonic
Supersonic
Whats the two types of shock waves ?
Normal shockwave - when air barrier is formed perpendicular to the air flow.
Oblique shockwave - ai barrier is formed at angle other than 90 degrees.
What happens to the velocity of the airflow when supersonic air Passes through normal shockwave ?
It drops.
What happens to the pressure of the airflow when supersonic air passes through normal shockwave ?
Increases
What happens to the density of the airflow to supersonic air when passing through a normal shockwave ?
Increases
Whats different to the supersonic airflow which passes through a normal shockwave to an oblique shockwave ?
Supersonic airflow passing through normal shockwave changes to subsonic whereas supersonic airflow passing through oblique shockwave stays supersonic.
What happens to the velocity of supersonic airflow which passes through an expansion wave ?
The velocity increases
What happens to the pressure and density of supersonic airflow when passing through an expansion wave ?
Pressure and density decrease
Where is the centre of pressure located on an airfoil In subsonic aircraft ?
25% of the cord from the leading edge.
Where is the centre of pressure located on an airfoil on a supersonic aircraft ?
50% of the cord from the leading edge.
What happens to the location that a normal shockwave forms On an airfoil when the aircraft’s speed increases ?
As the speed increase the location at which the shockwave forms on the airfoil travels towards the trailing edge ( rear of wing ) and begins to also form underneath the aircraft’s wing.
Whats the two ways to reduce wave drag ?
Using vortex generators
Applying the area rule
What is aerodynamic heating ?
When the air hits the stagnation point on the aerofoil which causes the velocity and energy to decrease to 0 which heats the material.
What can an aircraft’s compressor not withstand and how is this fixed ?
Cannot withstand supersonic airflow so a normal shockwave must be created in the intake which converts it to subsonic.
Whats the 4 designs used to change supersonic airflow into subsonic airflow ?
Normal shock diffuser
Oblique shock inlet
Variable supersonic inlet
C,D ducts
Whats the most common swept back angle for an aircraft’s wing ?
30 degrees
