mod 11.1 theory of flight

the fixed aerofoils are

wings or mainplanes

horizontal stabiliser or tailplane

vertical stabiliser or fin

the function of the wings is to

provide enough lift to support the aircraft

the tail section of a conventional aircraft that includes the horizontal and vertical stabiliser, rudder and elevators is known as

the empennage

the horizontal stabiliser is used to provide what type of stability

longitudinal pitch

additional stability can be met when the horizontal stabiliser has a

positive dihedral angle

conventional horizontal stabilisers are normally set at a

smaller or negative angle of incidence with respect to the wing cord line

the reason why the horizontal stab is set at a smaller or negative AOI is to

give a small downward force ( so the nose wants to go up)

a T tail configuration places

the horizontal stabiliser on top of the vertical fin

the T tail is used when engines are mounted on the sides so the

the horizontal stab is not affected by the exhaust area

the rudder and fin is more effective in the T tail connfiguration and is known as

the end plane effect

what is the positives of the T tail configuration

pitch control is not effected by the wing turbulence except in a unwanted deep stall configuration

what is the negative of the T tail configuration

the whole empennage needs to be strengthened to combat bending loads and thus is heavier

on some aircraft with a T tail the whole horizontal stab can move to trim as a alternative to

trim tabs

what appears to the be the most low-drag design

the flying wing

what is the disadvantage of the flying wing

controllability and stability

the vertical stabiliser creates what type of stability

directional

on a single engined propeller a yawing moment is the result of

the airflow rotaing and hitting one side of the vertical stabiliser

the yawing of a single engine propeller is combated by

the stabiliser to be offset

primary flight controls include

elevators, rudder, ailerons, roll spoilers

secondary control surfaces include

trim control (tabs) high lift devices (flaps and slats) speed brakes and lift dumpers

primary flight controls are used to

make the aircraft follow the correct flight path and to execute certain manoeuvres

secondary flight controls are used to

change the lift and drag characteristics of the aircraft or provide assistance to the primary

ailerons provide

lateral control of the aircraft

ailerons move the aircraft about the

longitudinal axis

ailerons move in what direction compared to each other

opposite

the up going aileron reduces lift causing

the wing to go down

the up going ailerons increases lift causing

the wing to go up

large aircraft use two sets of ailerons, the inboard is referred to as

high speed ailerons

at high speeds when there is inboard and out board ailerons what one operates

inboard

at low speeds the outboard ailerons operate os sometimes both because we want

maximum control especially when large movements are required

at high speeds if the outboard ailerons are used this could cause the wing to twist and produce

aileron reversal

once a input is produced to bank a aircraft, for the aircraft to return to straight and level

another input thats equal and opposite is needed

in a turn ailerons work in conjunction with

the rudder and or flaps

to little bank will cause the aircraft to

skid outwards

too much bank will cause the aircraft to

slip downwards

the use of spoilers as primary controls with aileron movement are known as

roll spoilers

roll spoilers are located

just inboard of the outboard ailerons

the control system that controls the roll spoilers is called the

spoiler/aileron mixer unit

in a turn the spoilers only deploy on the

down going wing

elevators govern pitch moments about what axis

lateral

elevators are hinged to the rear spar of the

horizontal stabliser

when the control column is pushed forward the elevators move

down

combined functions of the elevator and the horizontal stabiliser is known as the

stabilator, slab or all moving tail plane

the stabilator and the anti servo tab moves in what direction

opposite

the stabilator requires a heavy weight along a long arm in the fuse to give it

static balance

when horizontal surfaces are located forward of the wing this is known as

canards or foreplanes

canards stabilising force is directed

upwards

canards reduce drag from the

lift producing wing

compare to the main wing canards are a set at a angle that is

greater than the main wing so they stall first

the rudder rotates about the

vertical axis

pushing the rudder pedal to the right the nose of the aircraft turns to

the right

the range of the rudder is limited when moving at

high speeds

the dual function of elevators and ailerons is called

elevons

the dual function of the rudder and elevator is called

ruddervators

to calculate the lift force you multiply

the pressure difference by the wing area

the landing speed needs to be significantly slower than the clean stall speed this done be the use of

high lift devices

trailing edge devices are

flaps

leading edge devices are

slots slats kruger flaps

flaperons or droop ailerons are ailerons that act as

plain flaps while roll control is retained

to increase lift when increasing the speed or AOA is not a option what is the easiest option

increase the camber of the wing

vortex generators help

control the airflow over the wing

flaps can be lowered

manually electrically or hydraulically

flap settings mainly used are are

10,20,30 somtimes 40

the deflection of what flap setting gives more lift than drag

20 degrees anymore there is more drag then lift

to allow maximum flaps to be deployed without separation we use

slotted flaps

slotted flaps allow

high pressure air under the wing to flow over to the low pressure air on top

fowler flaps ride out of the wing on

tracks

due to there complexity fowler flaps have been replaced by

slotted flaps

short take off and landing aicraft allow the slat to fully extend to

allow the aircraft to fly at high angles of attack

some aircraft flaps are deployed by

mechanically or aerodynamic forces pulling them out

on large aircraft slats are normally deployed along with

flaps

when flaps are deployed the bulk of the lift moves to the

trailing edge

wing fences are fitted to aircraft with

swept wings

swept wings split the air into how many components

2

saw tooth leading edges are common on what type of aircraft

military

saw tooth leading edges are increase the wing chord on the outer portion that forms

a invisible wall of high velocity air

saw tooth leading edges fuction in the same way as wing fences but removes the

extra drag and weight penalty

winglets reduce drag by using the up flow from below the wing to produce

a forward thrust from the winglet

the region that flow turns from laminar to turbulent is known as the

transition point

the purpose of vortex generators is to

stimulate the boundary layer by mixing the high energy free stream air into the sluggish boundary layer

vortex generators protrude up about….and are in…

25mm…pairs

vortex generators weaken

shock waves and sock drag

sock induced separation can occur when an aircraft approaches its

critical mach number

seperation causes the controls to

buffet

stall wedges are mounted on

the leading edge in the root area

fixed trim tabs are adjusted manually by

a ground adjustable rod

controllable trim tabs are adjusted from the

flight deck

servo tabs act as a

power booster

moving a servo tab down will move the primary control

up

balance tabs help assist the pilot and are hinged

to the trailing edge of the primary control surface

the adjustable rod on a balance tab will alter the

displacement of the tab about the mid point datum

some balance tabs have more than on point of attachment “geared balance tabs” to alter the

range of tab deflection.

the function of a balance tab can also be combined with a trim tab by installing a form of

linear actuator in the rod “trim tabs”

anti balance tabs operate the same as balance tabs but in the

reverse effect

anti balance tabs move in what direction as the primary control surface

same direction

anti balance tabs add more load to provide

feel

spring tabs adds more assistance as

the aircraft flys faster

since the mass of a surface is behind the hinge line to counteract the negative flutter we used

mass balance in front of the hinge line

what are the two types of mass balances

integral and auxiliary

in order to overcome the high stick forces we use aerodynamic balancing such as

horn balance

insert hinge

aerodynamic balance panel