Drag & Wing Devices Flashcards
What is a spoiler?
Hinged panel on upper surface of wing
What do spoilers do when deployed?
“Spoil” or dump the lift produced as well as increasing drag & stability
When would a spoiler be deployed?
In descent
What are the 3 primary functions of spoilers?
-flight spoilers (speed brakes)
-ground spoilers (lift dumps)
-roll spoilers
What are speed brakes classified as?
High drag devices
When is a speed brake used?
During final approach to touchdown as well as after landing
When is a speed brake used?
During final approach to touchdown as well as after landing
What happens as air particles flow over the leading edge of a swept wing?
Air is split into two directions: one t right angles to the leading edge and the other follows the leading edge. This produces a span wise flow.
What does span wise flow have the effect of?
Thickens the boundary layer towards the wing tip making it prone to separation if the angle of attack is increased
Why do you want the wing to stall at the tip?
It gives a warning to the pilot and prevents a nose up pitch movement
What do wing fences do?
-reduces effects of span wise flow
-reduces wing tip stalling on swept wing
-obstructs spa wise flow & redirects it along the chord
What do saw tooth leading edges look like?
Zig zag cutout
What does a saw tooth leading edge have similar effects to?
Similar effects to wing fence
What does a saw tooth leading edge create and what are its effects?
Creates a small vortex that:
-increased drags
-reinvigorates airflow
-increases momentum
-delayed stall
What does a vortex generator do and how?
Re-energises slow moving boundary layer by mixing faster air
Produces lift that acts sideways
Causes vortex around tip of airfoil section
How are vortex generators typically arranged and how?
In opposing pairs so the vortexes mix
Are vortex generators at high or low angles of attack and why?
High angle of attack to the airflow in order to create stronger vortexes
What are stalling wedges classed as?
A leading edge device
Where are stall wedges located?
On inboard section of the wing
What shape is the cross section of a stall wedge?
Triangular cross section
What does a stall wedge encourage?
The root to stall first
What does a stall wedge do?
Initiates flow separation earlier than other parts of the wing when at high angles of attack
