Theory of Flight
6.03 Secondary Controls and
Secondary Effects of Controls
References:
FTGU pages 15, 28, 29
Review
1. What control surface causes roll?
2. What movement does the elevator create?
3. Which axis does yaw act around?
4. Name the 2 types of fuselage construction.
6.03 Secondary Controls and
Secondary Effects of Controls
• MTPs:
– Trim
– Spoilers and Dive Breaks
– Flaps
– Secondary Effects of Controls
– Coordination
Trim
• Trim tab: adjustable device located on the
trailing edge of control surfaces
• Purpose – alleviates pressure on the controls
• Other types of trim are bungees connected to
the control column
• Most often only on the elevator
Trim
The trim tab moves in the
opposite direction as the
control surface
Trim
• Trim in a glider
– No trim tabs
• Types
- side trim (bungee)
- stick trim (ratchet)
Bungee Trim
Spoilers & Dive Brakes
• Primarily used in glider
flying
• Spoilers – are hinged
plates on top of the wing
– disrupt the airflow over
the wing to “spoil” the lift
(Top)
• Dive Brakes – increase
drag (Bottom)
NASA applet - http://www.grc.nasa.gov/WWW/k-12/airplane/spoil.html
Spoilers & Dive Brakes
Purpose – allows the pilot to control the rate
of decent during final approach and
landing
- Spoilers and dive breaks increase drag
and decrease lift
Flaps
•
•
•
•
Increases the camber of the wing
This increases the lift and the drag
Known as a high lift device
Allows the aircraft to have a steeper approach
path with a decreased stall speed
• Allows glider pilot to fly slower in a thermal
Flaps
• Types of flaps
Secondary Effects
• The air movement over control surfaces when
they are moved causes adverse effects
• When you yaw you get Roll
• When you roll you get Adverse yaw
Roll from Yaw
Roll from yaw
• When rudder is
applied, the wing on
the outside of the
turn moves faster,
which causes it to
experience more lift
Faster = more lift
Roll from Yaw
MORE LIFT
CAUSES ROLL
TO THE LEFT
FASTER
YAW LEFT
Adverse Yaw from Roll
• When ailerons are applied the plane has a tendency
to yaw away from the lower wing because of
aileron drag.
• The wing that rises experiences more lift, but also
more induced drag.
Adverse Yaw from Roll
Right aileron UP
MORE LIFT
MORE DRAG
ROLL CAUSES
ADVERSE YAW
Left aileron DOWN
LESS LIFT
LESS DRAG
Coordination
• To turn the aircraft without causing
unnecessary drag, aileron and rudder
must be used.
• Using too much rudder will cause a
“skidding turn”.
• Using too little (or opposite) rudder will
cause a “slipping turn”.
Coordination
You slip in and skid out. Think of driving and skidding around a corner.
Confirmation
1.
How is adverse yaw created?
2.
Why is there roll when an airplane is yawed?
3.
What is the purpose of flaps?
4.
Name 2 types of trim.
5.
What is trim used for?
6.
What is the difference between slipping and skidding?
Confirmation
Draw on the
airplane where
the following go:
•
•
•
•
Flaps
Spoilers
Elevator Trim tab
Aileron Trim tab
C-130 Deploying Flares