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165
The Aeroplane Speaks. Fifth Edition
·
H. Barber
98
CHAPTER
III
RIGGING
In
order
to
rig
an
aeroplane
intelligently,
and
to
maintain
it
in
an
efficient
and
safe
condition,
it
is
necessary
to
possess
a
knowledge
of
the
stresses
it
is
called
upon
to
endure,
and
the
strains
likely
to
appear.
STRESS
is
the
load
or
burden
a
body
is
called
upon
to
bear.
It
is
usually
expressed
by
the
result
found
by
dividing
the
load
by
the
number
of
superficial
square
inches
contained
in
the
cross-sectional
area
of
the
body.
Thus,
if,
for
instance,
the
object
illustrated
above
contains
4
square
inches
of
cross-sectional
area,
and
the
total
load
it
is
called
upon
to
endure
is
10
tons,
the
stress
would
be
expressed
as
2-1/2
tons.
STRAIN
is
the
deformation
produced
by
stress.
THE
FACTOR
OF
SAFETY
is
usually
expressed
by
the
result
found
by
dividing
the
stress
at
which
it
is
known
the
body
will
collapse
by
the
maximum
stress
it
will
be
called
upon
to
endure.
For
instance,
if
a
control
wire
be
called
upon
to
endure
a
maximum
stress
of
2
cwts.,
and
the
known
stress
at
which
it
will
collapse
is
10
cwts.,
the
factor
of
safety
is
then
5.
COMPRESSION.--The
simple
stress
of
compression
tends
to
produce
a
crushing
strain.
Example:
the
interplane
and
fuselage
struts.
TENSION.--The
simple
stress
of
tension
tends
to
produce
the
strain
of
elongation.
Example:
all
the
wires.
BENDING.--The
compound
stress
of
bending
is
a
combination
of
compression
and
tension.
The
above
sketch
illustrates
a
straight
piece
of
wood
of
which
the
top,
centre,
and
bottom
lines
are
of
equal
length.
We
will
now
imagine
it
bent
to
form
a
circle,
thus:
Marker
Marker
Fine marker
White-out
Fine white-out
Circle
Paint
Unmarker
Hand
Scalpel
Dice
Sieve
Purify
Undo
Redo
Start over
