Flight Controls

Question 1

What are the five major stresses all aircraft are subject to?

Answer 1

1. tension
2. compression
3. torsion
4. shear
5. bending

Question 2

Describe Tension

Answer 2

1. the stress that resists a force that tends to pull something apart
2. tensile strength is measured in psi
3. calculate by dividing the load (in pounds) required to pull the material apart by its
   cross-sectional area (in sq inches)

Question 3

Describe Compression

Answer 3

1. the stress that resists a crushing force
2. the compression strength of material is measured in psi
3. it is the stress that tends to shorten or squeeze aircraft parts

Question 4

Describe Torsion

Answer 4

1. the stress that produces twisting
2. the torsion strength of a material is its resistance to twisting or torque

Question 5

Describe Shear

Answer 5

1. the stress that resists the force tending to cause one layer of a material to slide
   over an adjacent layer
2. screws, bolts, and rivets are especially subject to shearing force
3. the shearing strength of a material is equal to or less than its tensile or
   compressive strength

Question 6

Describe Bending

Answer 6

1. a combination of compression and tension

Question 7

What are Flight Control Surfaces?

Answer 7

1. hinged or movable surfaces through which
   the attitude of an aircraft is controlled
   during takeoff, flight, and landing

Question 8

What are the two major groups of flight control surfaces?

Answer 8

1. Primary or main flight control surfaces
2. Secondary or auxiliary control surfaces

Question 9

What is included in the primary flight control surfaces?

Answer 9

1. ailerons
2. elevators
3. rudder

Question 10

Describe Ailerons

Answer 10

1. ailerons are attached to the trailing edge of
   both wings
2. rotates the aircraft around the longitudinal
   axis

Question 11

Describe the Elevator

Answer 11

1. attached to the trailing edge of the horizontal
   stabilizer.
2. it alters aircraft pitch, which is the attitude
   about the horizontal or lateral axis

Question 12

Describe the Rudder

Answer 12

1. hinged to the trailing edge of the vertical
   stabilizer.
2. when the rudder changes position, the aircraft
   rotates about the vertical axis

Question 13

Describe some characteristics of primary control surfaces

Answer 13

1. usually similar in construction to one another
2. vary only in size, shape, and methods of
   attachment
3. must be balanced so they don’t vibrate or
   flutter in the wind

Question 14

Describe primary control surfaces on light aluminum light aircraft

Answer 14

1. construction is often similar to an all-metal
   wing
2. typically made from aluminum alloy structure
   built around a single spar member or torque
   tube to which ribs are fitted and a skin is
   attached
3. ribs are usually stamped out from flat
   aluminum sheet stock - holes in ribs lighten
   assembly
4. aluminum skin is attached with rivets

Question 15

Describe primary flight control surfaces on heavy and high performance aircraft, including gliders, home-built, and light-sport aircraft

Answer 15

1. primary control surfaces commonly made
   from composite materials
2. weight and strength advantages over
   traditional construction can be significant

Question 16

Describe the primary control surfaces of a fabric covered aircraft

Answer 16

control surfaces of fabric covered aircraft often have fabric covered surfaces

Question 17

Describe the primary control surfaces of aluminum skinned aircraft

Answer 17

typically have all aluminum control surfaces

Question 18

Failure to property balance a control surface could lead to what?

Answer 18

catastrophic failure

Question 20

Describe Ailerons

Answer 20

1. the primary flight control surfaces
2. move the aircraft about the longitudinal axis -
   movement of ailerons in flight causes plane to
   roll
3. usually located on the outboard trailing edge
   of each of the wings
4. built into the wings and calculated as part of
   the wings surface area
5. controlled by side to side motion of the
   control stick in cockpit or rotation of the
   control yoke

Question 21

Where are Ailerons located?

Answer 21

usually located on the outboard trailing edge of each of the wings

Question 22

How are Ailerons controlled

Answer 22

controlled by side to side motion of the control stick in the cockpit or rotation of the control yoke

Question 23

When the aileron on one wing deflects down, what happens to the aileron on the opposite wing?

Answer 23

it deflects upward

Question 24

The pilot’s request for aileron movement and roll are transmitted from the cockpit to the actual control surface in what ways?

Answer 24

system of cables and pulleys, push-pull tubes, hydraulics, electric, or a combination of these

Question 25

Hydraulic or electric fly-by-wire aileron controls can be found on what type of aircraft?

Answer 25

heavy and high performance aircraft

Question 26

A second set of ailerons located inboard on the trailing edge of the wings can be found on what type of aircraft?

Answer 26

heavy and high performance aircraft

Question 27

Why do heavy or high performance aircraft have a second set of ailerons on the trailing edge of the wing?

Answer 27

to provide lateral control and stability in flight

Question 28

What is an Elevator?

Answer 28

1. moves the aircraft around the horizontal or lateral axis 2. causes the nose of the aircraft to pitch up or down 3. elevator is hinged to the trailing edge of the horizontal stabilizer 4. controlled in the cockpit by pushing or pulling the control stick or yoke forward or aft 5. light aircraft use a system of control cables and pulleys or push-pull tubes to transfer info from the cockpit to the elevator 6. heavy and high performance aircraft use hydraulic power to transfer info from the cockpit to the elevator

Question 29

Describe the Rudder

Answer 29

1. causes an aircraft to yaw or move about the vertical axis 2. provides directional control and points the nose in the direction desired 3. most aircraft have a single rudder hinged to the trailing edge of the vertical stabilizer 4. controlled by a pair of foot operated rudder pedals in the cockpit

Question 30

What happens when the right rudder pedal is pushed forward?

Answer 30

it deflects the rudder to the right which moves the nose to the right - the left pedal is rigged to simultaneously move aft

Question 31

What happens when the left rudder pedal is pushed forward?

Answer 31

the nose of the aircraft moves to the left

Question 32

Name some dual purpose flight control surfaces

Answer 32

1. Elevons - perform combined functions of ailerons and the elevator 2. Stabilator - combines the action of both the horizontal stabilizer and the elevator 3. Ruddervator - combines the action of the rudder and elevator(possible on aircraft with V tail empennages

Question 33

Describe Flaps

Answer 33

1. secondary/auxiliary flight control surface 2. found on the inboard trailing edge of wings 3. extends the camber of the wing for greater lift and slower flight. 4. allows control at low speeds for short field takeoffs and landings 5. typically can extend 45-50 degrees 6. light aircraft - aluminum skin and structure flaps 7. heavy aircraft - aluminum or composite structures used

Question 34

Describe Trim Tabs

Answer 34

1. secondary/auxiliary flight control surface 2. found on the trailing edge of primary flight surfaces 3. reduces the force needed to move a primary control surface

Question 35

Describe Balance Tabs

Answer 35

1. secondary/auxiliary flight control surface 2. located on the trailing edge of primary flight control surfaces 3. reduces the force needed to move a primary control surface

Question 36

Describe Anti-balance tabs

Answer 36

1. secondary/auxiliary flight control surface 2. located on the trailing edge of primary flight control surfaces 3. increases feel and effectiveness of primary control surface

Question 37

Describe Servo tabs

Answer 37

1. secondary/auxiliary flight control surface 2. located on the trailing edge of primary flight control surfaces 3. assists or provides the force for moving a primary flight control

Question 38

Describe Spoilers

Answer 38

1. secondary/auxiliary flight control surface 2. located in upper and/or trailing edge of wing 3. decreases(spoils) lift. can augment aileron function

Question 39

Describe Slats

Answer 39

1. secondary/auxiliary flight control surface 2. located mid to outboard leading edge of wing 3. extends the camber of the wing for greater lift and slower flight 4. allows control at low speeds for short field takeoffs and landings

Question 40

Describe Slots

Answer 40

1. secondary/auxiliary flight control surface 2. located outer leading edge of wing, forward of ailerons 3. directs air over upper surface of wing during high angle of attack 4. lowers stall speed and provides control during slow flight

Question 41

Describe Leading edge flap

Answer 41

1. secondary/auxiliary flight control surface 2. located inboard leading edge of wing 3. extends the camber of the wing for greater lift and slower flight 4. allows control at low speeds for short field takeoffs and landings

Question 42

Describe plain flaps

Answer 42

1. form the trailing edge of the wing when the flap is retracted 2. plain flap is hinged so the trailing edge can be lowered 3. increases wing camber and provides greater lift

Question 43

Describe a split flap

Answer 43

1. housed under the trailing edge of the wing 2. a braced flat metal plate hinged at several places along the leading edge 3. when deployed, the split flap trailing edge lowers away from trailing edge of the wing 4. airflow follows the camber created by the lowered split flap, increasing lift

Question 44

Describe Fowler flaps

Answer 44

1. when deployed, lower the trailing edge of the wing and slides aft - increasing the area of the wing 2. creates more lift via increased surface area and wing camber 3. when stowed, the fowler flap retracts under the wing trailing edge

Question 45

Describe Slats

Answer 45

1. leading edge device which extends wing camber 2. can be operated independently of the flaps - has own switch in cockpit 3. gives ability to fly aircraft slower with a reduced stall speed

Question 46

List some characteristics of Spoilers

Answer 46

1. a device found on the upper surface of many heavy and high performance aircraft 2. it is stowed flush to the wings upper surface 3. when deployed - it raises up into the airstream and disrupts the laminar airflow of the wing - reducing lift 4. often honeycomb core flat panels 5. at lows speeds operates when ailerons operate to assist in lateral movement and stability 6. can also be deployed on both wings to act as speed brakes

Question 47

Describe Speed Brakes

Answer 47

1. found on the upper surface of the wings of heavy and high performance aircraft 2. designed to increase drag and reduce speed 3. speed brake control is located in the cockpit

Question 48

List the different types of flight control tabs

Answer 48

1. Trim 2. Balance 3. Servo 4. Anti-balance/Anti-Servo 5. Spring

Question 49

Describe a Trim tab

Answer 49

1. moves opposite the control surface 2. set by pilot from cockpit - uses independent linkage 3. statically balances the aircraft in flight - allows "hands off" maintenance of flight condition

Question 50

Describe a Balance tab

Answer 50

1. moves opposite the control surface 2. moves when pilot moves control surfaces - coupled to control surface linkage 3. aids pilot in overcoming the force needed to move the control surface

Question 51

Describe a Servo tab

Answer 51

1. moves opposite the control surface 2. directly linked to flight control input devices 3. can be primary or back-up means on control 4 aerodynamically positions control surfaces that require too much force to move manually

Question 52

Describe a Anti-balance/Anti-Servo tab

Answer 52

1. moves in same direction as control surface 2. directly linked to flight control input device 3. increases force needed by pilot to change flight control position / de-sensitizes flight controls

Question 53

Describe Spring tabs

Answer 53

1. moves opposite of control surface 2. located in line of direct linkage to servo tab 3. spring assists when control forces become too high in high speed flight 4. enables moving control surface when forces are high 5. inactive during slow flight

Question 54

List structures visible on wings that contribute to performance

Answer 54

1. Winglets 2. Vortex generators 3. stall fences 4. gap seals

Question 55

What is a Winglet?

Answer 55

1. an obvious vertical upturn of the wing's tip resembling a vertical stabilizer 2. designed to reduce the drag created by wing tip vortices in flight 3. usually made from aluminum or composite materialsW

Question 56

What is a Vortex generator?

Answer 56

1. small airfoil sections usually attached to the upper surface of a wing 2. designed to promote positive laminar airflow over the wing and control surfaces 3. usually made of aluminum and installed in a spanwise lines 4. can also be found on the fuselage and empennage

Question 57

What is a stallfence?

Answer 57

1. a chordwise barrier on the upper surface of the wing 2. used to halt the spanwise flow of air 3. reduces tendency for wing to stall in light aircraft 4. usually made of aluminum

Question 58

What is a gap seal?

Answer 58

1. used to promote smooth airflow in the gap areas found between the stationary trailing edge of a wing or stabilizer and the movable control surface 2. made from a variety of materials from aluminum, impregnated fabric, to foam and plastic