AMCR Flashcards
During World War 1 (WW1) and the early 1930s, what was the chosen material for
aircraft construction.
wood
Types of Wood
Solid Wood, Laminated Wood, Plywood
It is made from one solid log cut by quarter sawing for the
reduced chance of warpage. Most commonly use in aircraft wing
spars.
Solid Wood
It is made by gluing together two (2) to three (3) pieces of wood
with the same grain direction. Most used also in aircraft wing
spars and interchangeable with solid wood if it has the same
quality.
Laminated Wood
It is made from three (3) or more thin sheets of wood board
glued and pressed together so that its grain would be at an
angle to the successive layer.
Plywood
Species of Wood
Hardwood and Softwood
Comes from deciduous trees, this is a broad-leaved tree which looses its leaves in the winter
Hardwood
Comes from coniferous trees, an evergreen tree, needle-leaved, cone-bearing tree
Softwoods
Whatever species of wood
used for aircraft construction;
its grain orientation should
always be straight. A limit of
variation 1:15 is permitted,
indicating that the grain must
not have an angle of more
than an inch per 15 inches.
Grain Deviation
Are the part where the
tree branch sprouted from
the trunk. There are different
types of shapes of it
depending on the cut from
the wood e.g. round, oval, or
spiked.
Knots
It is a type of wood
imperfection caused by small
holes in the annual rings of a
tree. Woods with it are only allowed to
be used if they are 14 inches
apart and with a volume of
11/2-inches x 1/8-inch x 1/8-
inch deep.
Pitch Pockets
▪ NEVER a good wood for
aircraft construction and
repair.
▪ Wood taken from a tilted
tree as it grows that lead to
its wood having a denser and
weaker wood structure than
a normal grown tree.
Compression Wood
▪ Usually can be identified by
its irregular and thread-like
line on the grains
▪ Also, NEVER a good wood for
aircraft construction and
repair.
Compression Failure
▪ Most used in aircraft construction
▪ Free from defects
▪ Hight Strength-to-Weight ration
▪ Hight Quality Wood
Spruce
▪ Strength is far better than of spruce
▪ Heavier
▪ Difficult to work than spruce with the tendency of splitting
Douglas Fir
▪ Lighter than Spruce
▪ Equal or superior to Spruce in all properties
▪ Lower hardness and shock resistance to Spruce
Noble Fir
▪ Excellent working and gluing characteristics
▪ Strength is inferior to Spruce
Northern White Pine
▪ Exceptionally light weight
▪ Lacks structural strength
▪ Used as a core material for panels for sandwich-type requiring
light weight and rigidity
Balsa
▪ Heavier than Spruce
▪ Stronger than Spruce
▪ Most used in face sheet production of plywood in aircraft skins
Mahogany
▪ Heavy hardwood
▪ Good shock-resistance properties
▪ Recommended for face plies of plywood used in reinforcement
plates on wing spars and in propeller made from wood.
Birch
is a crack running through or across the annual grain
Check
is a crack or separation in which it can be seen from a
detached two annual rings along its boundaries
Shake
are caused by a decay on the wood usually appearing as
streaks in the grains.
Stains
the stain that uniformly discolored the
annual rings.
Decay
Decay on woods varies in color from
red to white stains
Decay on woods no matter what its stage will lessen the
_________ of the wood until it gets brittle with little to no strength
at all.
Toughness
Decay on wood is caused by
by fungi growing in damp woods that
eats its fiber.
Decay can be minimized by properly drying the wood up to __%
and the application of wood varnishes for the wood to be
protected from the elements.
20%
It is an important component in aircraft construction. Its application to aircraft
construction ranges from a thermoset plastic reinforced fiberglass to thermoplastic
material for windows.
Plastics
Plastics or resins can be classified to 2 different classification according to their
reaction to heat, what are those?
Thermoplastics and Thermosets
It can be mold to its desired shape
and by cooling it down will help it
maintain its shape.
Thermoplastics
It can also be molded and shaped but when
cooled down, it cannot be reheated to be
reshaped as it is fully cured (by heat or
catalyst).
Thermosets
Two types of Thermoplastics
Cellulose Acetate and Acrylic
- Transparent
- Light weight
- Tendency to shrink
- Tendency to turn its
transparent appearance to
slightly yellow shade
Cellulose Acetate
- Also known as Lucite,
Plexiglass, or Perspex - Stiffer that cellulose
- Clear transparent appearance
Acrylic
o Can also be used as an adhesive and bonding agent
o Can be combined and poured into different kind of materials
Thermoset Plastics
Types of Thermoset Plastics
Polyester Resin, Vinyl Ester Resin, Phenolic Resin, Epoxy, Polyimides, Polybenzimidazoles (PBI) , Bismaleimides (BMI)
- Low-cost
- Fast treating
- Common handling
techniques for Fiber-
reinforced polyester:
o Autoclaving
o Pultrusion
o Filament winding
o Press (vacuum bag)
molding
o Wet layup
o Injection molding
o Metal molding
Polyester Resin
- All properties and
characteristics are the same as
Polyester resin - Higher corrosion resistance
than polyester resin - Higher mechanical properties
than polyester resin
Vinyl Ester Resin
- Also known as Phenol-
formaldehyde resin - Shows low smoke and
flammability characteristics - Used in interior components
Phenolic Resin
- Have different variety of viscosity from liquid to solid
- Used as structural adhesives
and for prepreg materials - High strength and modulus
- Low volatility
- Exceptional adhesion
- Low shrinkage
- Exceptional chemical resistance
- Ease of use
- Brittle
- Reduced mechanical properties
when subjected to moisture - Usually longer to process than polyester resin
- Common handling techniques:
o Autoclaving
o Pultrusion
o Filament winding
o Press (vacuum bag) molding
o Resin transfer molding
Epoxy
- Mostly used in high-
temperature settings e.g.:
o Airframe structure
o Hot engine
o Circuit boards
* Excellent high thermal
resistance
* Oxidative stability
* Low amount of thermal
expansion
* Have high-temperature curing
Polyimides
- Best used in environments where
dangerously high heat-resistant
resin is needed. - Available in the form of fiber and
adhesive
Polybenzimidazoles (PBI)
- Higher temperature and toughness
characteristic than epoxy resin - Used in airplane engines and high-
temperature components - Common handling techniques is
similar to epoxy resin:
o Autoclave
o Injection molding
o Resin transfer molding
o Sheet molded compound
(SMC)
Bismaleimides (BMI)
In the early times, finely
woven organic fabrics like
__________ have been
the initial choice for covering
airframes.
Cotton and Linen
Types of Weaves
Plain Weave, Twill Weave, Satin Weave, Basket Weave, Leno Weave, Mock Leno Weave
the direction along the length of fabric
Warp
the direction across the width of the fabric.
Fill or Weave
the number of threads per inch in warp or filling.
Count
the number of yarns making up a thread.
Ply
a cut, fold, or seam made diagonally to the warp or fill threads.
Bias
an edge which has been cut by machine or special pinking
shears in a continuous series of Vs to prevent raveling.
Pinked Edge
condition of polyester fabric upon completion of the production
process before being heat shrunk.
Greige
brushing or spraying where the second coat is applied 90° to
the direction the first coat was applied. The two coats together make a single
cross coat.
Cross Coat
Types of Fabric Covering Processes
Blanket Method, Envelope Method
In this method, fabrics are attached to the airframe by trimming multiple
flat sections and using adhesives to stick to the airframe.
Blanket Method
This method uses precut and pre-sewn envelope fabrics made-to-fit the
airframe where it is needed to be placed. Through the help of patterns,
fabrics can be cut and sewn to the exact size where it needed to be slid
into position and will be fastened to the airframe by adhesives.
Envelope Method
Types of fibers
Glass Fiber, Ceramic Fiber, Kevlar Fiber, Graphite Fiber / Carbon Fiber
can be in the form of woven cloth (higher cost) or loosen
mat(cheaper). Provide the resin material matrix with enhanced strength and
durability.
Glass Fiber
a type of glass fiber designed to be used in high-temperature
components. It is however more expensive and heavier in weight of glass
fiber.
Ceramic Fiber
frequently used type of fiber where high impact resistance is
needed. Identifiable by its soft yellow color in the form of woven cloth.
Kevlar Fiber
obtained from Rayon fibers where the cellulose is heated
and stretched to change the molecular structure of the fiber into an extremely
lightweight, strong, and tough material.
Graphite Fibers / Carbon Fibers
It is used to stop the entry of foreign materials like dirt, water, or air, and to
stop a seepage of fluids, gasses, or air. It is also a vibration absorbent, noise
deadening, and impact load safeguard.
Rubber
Types of Rubber
Natural Rubber, Synthetic Rubber
has better ease of
processing and properties
including tensile strength,
tear strength, elasticity,
flexibility, and accumulated
heat buildup than synthetic
rubber
Natural Rubber
is available in different
composition that gives
it different properties
depending on where it
will be used.
Synthetic Rubber
Types of Synthetic Rubbers
Butyl, Buna-S, Buna-N, Neoprene, Thiokol, Silicone, Silastic
i. Superior resistance to gas
saturation
ii. High resistance to
deterioration
iii. Low water absorption
iv. Good temperature
resistance
v. Lower physical properties
than Natural rubber
vi. Best used for phosphate
ester hydraulic fluid (also
known as Skydrol), silicone
fluids, ketones, acetones,
and gases.
Butyl Rubber
i. Have the same physical
and processing
characteristic to natural
rubber
ii. Water resistant
iii. Good resistance to heat in
the absence of harsh
flexing
iv. Poor resistance to oil,
gasoline, solvents, and
concentric acids
v. Better substitute to natural
rubber
Buna-S Rubber
i. Also known as nitrile
rubber
ii. Exceptional resistance to
hydrocarbons and
solvents
iii. Low resistance to
solvents at low
temperature
iv. Good resistance to
abrasion
v. Used in automotive and
aviation industry to handle
oil and gasoline hoses,
seals, tank lining, and for
gaskets.
Buna-N Rubber
i. Superior oil resistance
ii. Good to use with
nonaromatic gasoline
but bad with aromatic
gasoline
iii. Have similarity to
natural rubber in the
appearance and texture
iv. Tougher than natural
rubber
v. Tear and abrasive
resistance are less than
of natural rubber
vi. Exceptional resistance
to the elements
Neoprene Rubber
i. Also known as
polysulfide rubber
ii. Best resistance to
deterioration
iii. Worst physical
characteristics
iv. Have similarity in
usage as Buna-N
Thiokol
i. Best to use where flexibility is needed in high and low
temperatures
ii. Good resistance to oils but adversely reactive to aromatic and
nonaromatic gasoline
Silicone
i. One of the best kind of silicones
ii. Good for insulating electrical and electronic components
Silastic
Edge of cloth to prevent raveling
Selvage Edge
