Mod 11 - Theory of Flight

Question 1

Explain Canard Configuration.

Answer 1

• Canards are used mainly on high-speed A/C.
• Replaces the horizontal stabilizer.
• The canard needs to stall before the wing or else ‘deep stall will occur.’

Question 2

Whats an elevon?

Answer 2

• An elevon incorporates the elevator and aileron into one control surface.

Question 3

Whats a Variable Incidence Tailplane? (FD)

Answer 3

• This is when the whole tailplane is moved by a screw jack to trim the A/C due to changes of C of G (fuel movement).
• Controlled by screw jack, separate from the hydraulic system

Question 4

What is Adverse Yaw? (FD)

Answer 4

• Adverse yaw is caused when the A/C rolls on way and yaws in the opposite direction.
• If an A/C banks left, the right wing will have higher induced drag, and the left wing will have higher profile drag. At slower speeds, the drag on the downgoing wing (right wing) will have higher drag than the upgoing wing (left wing) causing the A/C to yaw in the opposite direction.
• 1: Differential Airleron: This is when the downgoing aileron deflects less than the upgoing.
• 2: Frise Ailerons: The upgoing wing aileron leading edge will protrude into the airflow causing profile drag.

Question 5

Explain Airleron Reverse.

Answer 5

• This happens on supersonic A/C when the wing can twist due to the forces. Due to the twist, the aileron compensates this by acting in the opposite direction.

Question 6

What are Lift Dumper Spoilers? (FD)

Answer 6

• These spoilers are isolated by the ‘WOW’ microswitch ensuring the spoilers aren’t fully activated during flight.
• The spoilers are fully activated when the weight is on wheels.

Question 7

Explain/Draw Split Flaps.

Answer 7

• 60% lift increase.
• 14% angle of aerofoil at max lift.
• Increases camber.
• Nose Down pitching moment.

Question 8

Explain Vortex Generators.

Answer 8

• Small plates protruding from the aerofoil surface.
• Normally 25mm high or 3x the boundary layer thickness.
• They produce vortices and pull in air from the boundary layer in front of control surfaces.

Question 9

3 Conditions have to be satisfied for spoilers to used as lift dumpers.

Answer 9

1 - Flaps Activated.
2 - Weight on wheels.
3 - Throttle at idle.

Question 10

2 Things to increase root stall.

Answer 10

1 - Washout.

2 - Stall Strip. (Toblerone)