ACRM (1-50) S1

Tension

Tension

the stress that resists a force that tends to pull something apart

Compression

the stress that resists a crushing force

Torsion

the stress that produce twisting

Shear

the stress that resists the force tending to cause one layer of a material to slide over an adjacent layer

Bending

a combination of compression and tension

Truss structure

uses struts and wire-based wings

Monocoque structure

the skin itself carries the structural loads which allow the aircraft to be built with a more streamlined shape

Semi-monocoque structure

the skin is fastened to a sub-structure or skeletal framework, which allows loads to be distributed between the structural components and the skin of the aircraft

Symmetrical airfoil

the curvature of the upper camber is the same as the curvature of the lower camber

Upwash

deflection of the oncoming airstream is upward and over the wing

Downwash

downward deflection of the airstream as it passes over the wing and past the trailing edge

Compression strut

compression members which separate the spars that may be either steel tubing or heavy wall aluminum alloy tubing

Wing Ribs

are the structural crosspieces that combine with spars and stringers to make up the framework of the wing

Wing spars

are the principal structural members of the wings that resist torsional and bending loads

Compression Ribs

have been specially strengthened to take compressive loads

Drag Wires

the wires that extend from the front spar to the rear spar and run diagonally from the inboard to the outboard that opposes any force that tends to drag against the wing and pull it backward

Anti-Drag Wires

the wires that run between the front and rear spar and run diagonally from outboard to inboard that oppose any force that tends to move the tip of the wing forward

Gusset

a thin mahogany plywood plate attached to two or more members to carry the stresses from one member to the other

Nose Rib/False Ribs

Prevents air loads from distorting the leading edge

Cantilever wing

internally braced wings not requiring external support

Chemical Milling

good for quickly removing large amounts of material

Electrochemical Milling

used for cutting complex shapes or deep grooves

Nacelles

are streamlined enclosures used primarily to house the engine and its components

Cowling

the detachable panels covering those areas into which access must be gained regularly, such as the engine and its accessories

Flutter

occurs when an out-of-balance condition causes a control surface to oscillate in the airstream, typically increasing in frequency and amplitude until the control surface fails catastrophically

Static Stability

the tendency of the airplane to return to its original position

Dynamic stability

concerned with the way the restorative forces act with regard to time

Positive Stability

the airplane will tend to return to its original position

Negative Stability

the airplane tends to not return to its original position

Neutral Stability

the airplane tends to not return to its original position, nor will tend to move further away

Roll

airplane movement at the longitudinal axes of rotation

Pitch

airplane movement at the lateral axes of rotation

Yaw

airplane movement at the vertical axes of rotation

Lateral

axes of stability when the airplane is rolling

Longitudinal

axes of stability when the airplane is pitching

Directional

axes of stability when the airplane is yawing

Ailerons

the primary flight control surfaces that move the aircraft about the longitudinal axis

Elevator

the primary flight control surface that moves the aircraft around the horizontal or lateral axis

Rudder

the primary control surface that causes an aircraft to yaw or more about the vertical axis

Stabilator

a combination of the horizontal stabilizer and elevator

Ruddervator

a combination of the rudder and elevator

Flaperon

a combination of the flap and aileron

Flaps

found in the inboard trailing edge of wings which extends the camber of the wing for greater lift and slower flight that allows control at low speeds for short field takeoffs and landings

Balance Tabs

a type of tab that is directly linked to the control surface which allows it to automatically move opposite to the control surface

Anti-balance/Anti-servo tab

a type of tab that moves along with the control surface which increases feel and effectiveness of primary control surface

Servo Tabs

located at the trailing edge of a primary flight control that assist or provide the force for moving a primary flight control

Spoilers

located at the upper and or trailing edge of the wing that decreases lift and can augment aileron function

Slats

located at the mid to outboard leading edge of the wing which extends the camber of the wing for greater lift and slower flight. It allows control at low speeds for short-field takeoffs and landings

Slots

located at the outer leading edge of the wing forward of ailerons which directs air over the upper surface of the wing during high angle attack or lowers the stall speed and provides control during slow flight

Leading edge flap

located at the inboard leading edge of the wing that extends the camber of the wing for greater lift and slower flight. It also allows control at low speeds for short field takeoffs and landings