8.3 theory of flight

Question 1

the four fundamental fources that govern how an aircraft flies are

Answer 1

lift
weight
thrust
drag

Question 2

the total weight of the aircraft is represented where

Answer 2

the centre of gravity

Question 3

it is common to lump the total lift produced by the wing to a single point known as

Answer 3

the centre of pressure

Question 4

common engine locations include

Answer 4

in front of the nose, under the wings, internal to the fuselage and on the rear fuselage.

Question 5

the forward motion of an aircraft is largely determined by

Answer 5

thrust and drag

Question 6

glide ratio =

Answer 6

ratio of the distance forward to the distance downward

Question 7

if two aircraft have same lift to drag ratio but weigh differently and start gliding from same altitude what happens.

Answer 7

heavier aircraft glides at higher airspeed and arrives at the same touch down point quicker than the lighter aircraft.

Question 8

optimum AOA is typically

Answer 8

4 degrees

Question 9

high performance glider will have an LD max of

Answer 9

between 25 and 60

Question 10

an aircrafts LD max is

Answer 10

12-20

Question 11

in steady flight the sum of the opposing forces is what

Answer 11

always zero

Question 12

the primary factors most affected by perfromance are

Answer 12

rate of climb
ceiling
payload
range
speed
stability
fuel economy
TO and landing distance
manoevrability

Question 13

induced drag is high or low at low speeds

Answer 13

high and decreases as the speed increases

Question 14

parasite drag does what as speed increases

Answer 14

increases

Question 15

thrust is measured in ..

Answer 15

pounds (lb) or newtons (N)

Question 16

when regarding fuel performance what are two important factors

Answer 16

to extract max flying distance from a given fuel load

to fly a specified distance with a minumum expenditure of fuel

Question 17

the values of specific range vs speed are affected by 3 principal variables

Answer 17

aircraft gross weight
altitude
the external aerodynamic config of the aircraft

Question 18

the force of lift during a bank is divided into vertical and horizontal components which are at a right angle to eachother. what are they called

Answer 18

vertical = vertical component of lift

horizontal = centripetal force or horizontal component of lift

Question 19

if aircraft is to maintain altitude during a turn what must happen

Answer 19

thr lift must be equal to resultant of centrifugal force and weight

Question 20

to compensate for added lift during a turn, which would result if the airspeed were increased what must happen

Answer 20

the AOA must be decreased or bank angle increased.

Question 21

to remain a constant rate of turn as airspeed is increased what must happen

Answer 21

AOA must remain constant and bank angle increased

Question 22

slipping turn =

Answer 22

centrifugal force is less than horizontal lift

Question 23

skidding turn =

Answer 23

centrifugal force is greater than horizontal lift

Question 24

limit load factor is

Answer 24

highest load factors that can be expected in normal operation

Question 25

the load factor is

Answer 25

resultant force of lift in a turn divided by the weight aka G-load

Question 26

load factor increases at terrific rate after bank has reached what angle

Answer 26

45 or 50 degrees

Question 27

load factor for any aircraft in a coordinated level turn at a 60 degree bank is how many g

Answer 27

2g

Question 28

load factor in a 80 degree turn is how many g

Answer 28

5.76 g

Question 29

an aircrafts stalling speed increases in proportion to the square root of what

Answer 29

the load factor

Question 30

the steeper the bank angle, the greater the centrifugal force but does the load factor increase or decrease

Answer 30

increases

Question 31

stall characteristics include

Answer 31

distinctive loss of lift
sudden nose pitch down
warnings such as buffeting before stall occurs

Question 32

stalls commonly occur at what airspeeds

Answer 32

slow

Question 33

V-n diagrams shows what

Answer 33

is another way of showing limits of aircraft performance. It shows how much load factor can be safely achieved at different airspeeds

Question 34

V-n diagram is dependant on factor such as

Answer 34

the aircrafts gross weight
the config of aircraft flaps, landing gear position etc.
the applicable altitude

Question 35

structural limits. under any loading even 1g what will happen

Answer 35

the aircraft structutre will flex

Question 36

structural limits can also be referred to as

Answer 36

acceleration limits or limit load factors

Question 37

aeroelastic limits studies what

Answer 37

interactions between the inertial, elastic and aerodynamic forces that occur when elastic body is exposed to fluid flow

Question 38

Aeroelastic limit is frequently referred to as the

Answer 38

redline airspeed

Question 39

ultimate structural limits will result in structural failure of some components and are outside normal operating envelope of the aircraft.

Answer 39

usual design rule is for ultimate structural limit to be 150% of the structural limit.

Question 40

lift augmentation systems are devices installed on the wing and do what

Answer 40

increase lift at given speed .
useful at low speeds as they reduce the stall speed of the aircraft.

Question 41

the principal lift augmentation devices are

Answer 41

flaps - trailing edge and leading edge
slats and slots - either auto or controllable by pilot
boundary layer control - used to re-enegrise the boundary layer

Question 42

plain flap is a basic hinged design to trailing edge.

Answer 42

-allows pilots to fly at steeper angle on approach without increasing airspeed.
-plain flap provides nose down pitching.
-50-55% increase in max lift at 12% AOA

Question 43

split flap consists of two sections. fixed upper part is extension on top of trailing edge, while lower is moveable and pivots to generate drag.

Answer 43

split flap provides a nose down ptich with a 60-65% increase of max lift at 14 degree AOA

Question 44

slotted flap is most common on small and large commercial aircraft. gap between wing and flap

Answer 44

a single slotted flap provides 65-70% increase in lift at 16 degree AOA.

Multi slotted flaps give 70% increase in lift at 18 degree AOA

Question 45

fowler flap one of the most common in modern aircraft because they provide significant lift with minimal drag.

Answer 45

on set of rails or tracks.
provides nose down pitch with 95% increase in max lift at 15 degree AOA

Question 46

krueger flaps are fitted where

Answer 46

bottom of the leading edge and deploy down and forwards, increasing wings camber to generate more lift .

Question 47

leading edge flaps are always used in conjunction with

Answer 47

trailing edge flaps and are controlled directly from the flight deck or linked.

Question 48

cuffs are fixed aerodynamic devices that

Answer 48

are secured to the leading edge, extend leading edge down and forward. they increase camber and CL max and lower ac stall speed

Question 49

slats do what

Answer 49

prevent flow separation by re-enegising the boundary layer.

Question 50

a leading edge slot is what

Answer 50

similar to a slat but is a fixed aerodynamic feature of the wing. reduces stall speed and promotes good low - speed handling qualities

Question 51

a leading edge slot can increase max lift coefficient of an aerofoil section by how much

Answer 51

40%

Question 52

what are vortex generators and what do they do

Answer 52

metal projections on the upper surface of the wing. VG’s improve performance and controllability of the aircraft, particularly at low speeds. in the climb and at high AOA.
-they also help prevent flow separation by creating mini vortices

Question 53

what are winglets and what do they do

Answer 53

small upturned structures on the end of the wing. winglet solves problem of wingtip vortex
it is torn apart and distributed vertically.

Question 54

benefits of winglets are

Answer 54

reduced fuel consumption
increased range
improved performance
lower emissions