Lesson 13: Aircraft
Structures And Flight
Controls
Aircraft Structures
• Truss-type Structures
• Had struts and wire-braced wings
• Occupants sat in open cockpits
• Cockpits fabric-covered
• Stressed-skin Structures
• All of the structural loads are carried by the
skin.
• Thin wood skin
• Or aluminum-alloy sheets
Aircraft Structures
• Monocoque
• Virtually no internal framework
• Semi-monocoque
• Internal arrangement of formers and stringers
is used to provide additional rigidity and
strength to the skin.
Semi-monocoque
Airframe Units:
• Fuselage
• Wings
• Stabilizers
• Flight control surfaces
• Landing gear
Airframe Units:
Vertical
Stabilizer
Horizontal
Stabilizer
Rudder
Elevator
Cowling
Flap
Aileron
Structural Loads/Stress
• Five Types Of Stress
•
•
•
•
•
Tension
Compression
Bending force
Torsion
Shear force
Structural Loads/Stress
Structural Loads/Stress
• Deformation
• Nonpermanent Deformation
– Deformation disappears when the load is
removed.
• Permanent Deformation
– Wrinkles observed on top of wing and
bottom of horizontal stabilizer.
– Stretch marks on the bottom of the wing or
top o the stabilizer. (positive g’s)
Materials For Aircraft Construction
• Wood
• Aluminum Alloys
• Honeycomb
• Magnesium
• Stainless Steel
Materials For Aircraft Construction
Structures
Structures
• Wing Construction Truss-type
Structures
• Stressed-skin Wing Construction
Cantilever Wing
Control Surface Construction
Control Surface Construction
• Control Surface Flutter
• Control Surface must be mass balanced so that
their center of gravity does not fall behind their
hinge line.
Fuselage Construction
• Truss Fuselage construction
• Pratt truss
• Warren truss
• Stressed-skin Structure
• Monocoque
• Semi - Monocoque
• Pressurized Structure
Flight Controls
Flight Controls
Pitch Control
• Elevators
• Sole function is to change the angle of attack
of the airplane, which alters its speed, lift and
drag.
Pitch Control
Pitch Control
• Stabilator
• All-movable tail
• Anti-servo tab
• Ruddervators
• Provides both longitudinal and directional
stabilization and control.
Lateral Or Roll Control
• Ailerons
• Rolling action produced is the primary method
of lateral control on most aircraft.
Lateral Or Roll Control
Directional Control
• Adverse aileron yaw
• The aileron that moves downward creates lift
and induced drag.
• Induced drag pulls the nose of the airplane
around in the direction opposite the way the
airplane should turn.
Directional Control
• Rudder
• Rotates the airplane about its vertical axis
(Yawing)
• Also provides a form of roll control because
the application of rudder causes yaw which will
induce a roll.
Directional Control
Trim Controls
Trim Controls
• Trim Tabs
• Balance Tab
• Anti-Servo Tab
• Servo Tab
• Spring Tab
• Adjustable Stabilizer
Trim Tabs
Balance Tab
Anti-Servo Tab
Servo Tab
• Used on large aircraft when the control forces are
too great for the pilot to manually move.
• Flight control column moves the tab on the control
surface and this aerodynamically moves the main
control surface.
Adjustable Stabilizer
Fixed Trim Tab
Aerodynamically Balanced Control
Surface
• Overhang deflects to the opposite side of the
fuselage from the main rudder surface to produce
an aerodynamic force that aids the pilot.
Stall Strip and Vortex Generators
Auxiliary Lift Devices
Flaps
• Change the camber of the wing and increase both its
lift and drag for and given angle of attack
• Moved by cables form an electric motor driven
jackscrew.
Flaps
Leading Edge Devices
• Delays the the airflow separation caused by a stall to
a higher angle of attack.
• Increases the energy of the air flowing over the
surface.
Fixed Slot
Movable Slat