M11.1 Flashcards
What is also known as a primary control surface on large aircraft to help assist in roll
Roll spoilers
What are the two different kinds of canards
Lifting and control
What is an advantage of the V tail
Weight saving because no additional control surface is needed
What is the purpose of the slats and the flaps
Produce lift for low speed flight
What is used to move the slats and the flaps
The flap lever
Nose up/nose down around what axis
Lateral
Roll wing up and wing down around which axis
Longitudinal axis
Yaw nose left nose right around which axis
Vertical axis
What is the stabiliser also known as
The all moving tail
What are the two types of canards
Lift and control
What is the advantage of the v tail
Saving weight because no vertical stabiliser is needed
What are the disadvantages of the v tail
No full deflections both ways can be achieved
More complicated
What is pitch trim achieved by
THS
Which way does the balance tab move compared to the control surface
The opposite way
Which way does an anti balance tab deflect
The same direction as the control surface
How much does the fowler flap increase lift by
95%
What are wing fences used for
To combat span-wise flow
What is a vortex generator used for
Improve boundary layer control
In what region is the air said to be incompressible
Subsonic
In which region is the air compressible
Supersonic
What speeds are subsonic
0.8 Mach and below
What are the regions of transonic
0.8 and 1.2
What is supersonic speed
1.2 and 5
What is Mach number
Aircraft speed divided by speed of sound
What is the critical Mach number
The highest speed possible with out going supersonic
What speed does a normal shock wave take place
Mach 1.2
What are the characteristics of a transonic profile
- Flatter upper surface
- More curved leading edge
- Thinner trailing edge
What are the two main types of waves formed during supersonic flow
- Shock waves
- Expansion waves
What are the 3 axis of motion
- Lateral
- Longitudinal
- Vertical
What flying controls move around the lateral axis
Elevators
What is meant by aileron lockout
Outboard ailerons become inactive in high speed flight
What are the advantages of a V tail
No need for horizontal stab so saves weight
What are the disadvantages of a V tail
- Less stability
- Adjustment is complicated
- no full rudder or elevator deflection at the same time
- Needs larger surface area
What are the secondary flight controls
Lift devices and trim systems
What lift device gives the maximum increase in lift
Fowler flap
What are trim systems used for
Compensate for imbalance in the aircraft
How do vortex generators reduce wave drag
They produce a vortex that transferres energy from the free air stream to the boundary layer
What are the 3 types of balance that are used on flying controls
- Balance tab
- Anti balance tab
- Balance panel
Does the balance tab aid the pilot
Yes
What is an anti balance tab
Moves in the same direction as the control surface but harder for the pilot
What part of air changes with the onset of transonic flight
Compressibility
What is Mach number
Speed of aircraft compared to speed of sound
What is the critical Mach no
Highest aircraft speed before hitting Mach 1
What design delays Mach crit
Swept back wings
Where does supersonic flow first occur on an airfoil
On top of the wing
What happens to air velocity in expansion waves
Increases
Why does flow separation occur behind a shockwave
The boundary layer doesn’t have enough kinetic energy to withstand the large increase in static pressure
When does a bow wave form on the leading edge
When flight speed exceeds the speed of sound
What drag increases due to the use of vortex generators
Parasitic drag
Which wing is known as the rear loaded with
Transonic
What are the possible advantages of the rear loaded wing
- Performs well within the transonic range
- Less drag
- Smaller wing
- Better low speed characteristics
How is tuck under avoided on modern aircraft
Horizontal stabiliser - Mach trim
What are the two type of aerofoils that form on supersonic profiles
Normal and oblique
Which type of shock wave causes an increase in the velocity of airflow
Expansion wave
How does a vortex generator re energise and boundary layer
It takes high energy from the outside and mixes it with low energy air from the inside
What would be the effect on the aircraft with the slats are selected out
Increased lift, decrease angle of attack, increase drag
When would the boundary layer separate from the serif oil section
When the normal shock wave forms
What are the advantages and disadvantages of anti balance tabs
Advantage - increase efficiently of control surface
Disadvantage - more effort is required to move control surface
What detrimental effect does aerodynamic heating have on metals
Loses its strength. 80% with ally if temp above 250 degrees
What is the point at which airflow over a wing is at its maximum but below the speed of sound
Critical Mach point
What is the normal sweep angle on modern aircraft
30 degrees
What is formed at a supersonic intake to ensure good airflow to the engine
Oblique shock wave
There is a large increase in what behind the shock wave on an airfoil section
Static pressure
What are the differences between normal wing profile and a transonic profile
Transonic wing has flatter upper surface, more curved leading edge and thinner trailing edge
What is monocoque construction
Frames formers and bulkheads with skin carrying the primary stress
What is a semi monocoque construction
Same as monocoque but with longitudinal members reinforcing the shell
What is safe life
The period in which failure is unlikely
What 3 surface treatment techniques are used on aluminium
- anodising
- chemical conversion coating
- wash primer
What is a body station
Vertical plane right angle to the body centreline
What is a waterline
Horizontal plane at right angle to the body stations
What is bbl short for
Body buttock line
What are the purpose of frames
Structural support and to attach other things to
What are the purpose of stringers
Some structural support but mainly give shape and attachment points for the skin
What are the purpose of floor beams in aircraft structure
Carry tension loads during pressurisation
What spacing is normally used between frames
20 inches
At production breaks how are stringers attached together
Stringer splices
What shape clips can be used to attach stringers to frames
T shaped
