ENGINES
1
–
BASIC
GAS
LAWS
BOYLE’S
LAW
TRANSFER
OF
HEAT
• Assumes
constant
temperature
• Conduction
• Product
of
pressure
and
the
volume
is
• Convection
constant
providing
temperature
of
the
gas
• Radiation
remains
unchanged.
• P1
V1
=
P2
V2
CHARLE’S
LAW
• Assumes
temperature
is
varied.
• With
constant
pressure,
if
temperature
increases
then
volume
must
increase.
• P1
/
T1
=
P2
/
T2
• With
constant
volume,
if
temperature
increases
then
pressure
must
increase.
• V1
/
T1
=
V2
/
T2
GENERAL
GAS
EQUATION
• All
three
statements
combined
!! !! !! !!
• !!
= !!
, ENGINES
2
–
LAWS
OF
MOTION
NEWTONS
FIRST
LAW
FORCE
THRUST
CALCULATION
• A
body
at
rest
will
remain
at
rest
and
a
body
• Force
=
Mass
x
Acceleration
• F
=
m
x
a
in
motion
will
continue
in
uniform
• SI
Unit:
N
(Newton)
𝑊
𝐹 = × 𝑎
(direction
and
speed)
motion
unless
it
is
• Imperial
Unit:
lbsf
(Pounds
force)
𝑔
acted
on
by
an
outside
force.
• Weight
of
airflow
through
propeller
is
800
lbs/s,
the
inlet
velocity
is
0
ft/s
and
the
DENSITY
outlet
velocity
is
160
ft/s.
Calculate
thrust?
NEWTONS
SECOND
LAW
• Thrust
is
a
force
so
equation
above
is
used.
• Density
=
Mass
/
Volume
• The
acceleration
produced
in
a
mass
by
the
• Varies
with
temperature
and
pressure
800
application
of
a
force
is
directly
𝐹 = × 160 = 4000 𝑙𝑏𝑠𝑓
32.20
proportional
to
the
force
and
inversely
proportional
to
the
mass.
• F
=
m
x
a
MOMENTUM
• Momentum
=
Mass
x
Velocity
NEWTONS
THIRD
LAW
INERTIA
• To
every
action,
there
is
an
equal
and
opposite
reaction.
• Tendency
of
a
body
to
preserve
its
state
of
rest
or
uniform
motion.
WEIGHT
AND
MASS
• Weight
is
the
force
with
which
the
gravity
of
the
earth
attracts
a
mass.
• W
=
m
x
g
• Accel
due
gravity:
32.20
ft/s2
or
9.81
m/s2
, ENGINES
3
–
PISTON
ENGINE
CONSTRUCTION
BASIC
PRINCIPLE
VOLUME
&
PRESSURE
RELATIONSHIP
TYPES
OF
ENGINES
• Convert
linear
to
rotary
motion.
• In-‐Line
Engine
o Poor
cockpit
visibility
• Inverted
In-‐Line
Engine
4
STROKE
CYCLE
o Improved
visibility
o Suffers
from
hydraulicing
(turning
over
• A.K.A
The
Otto
Cycle
before
start
is
required).
• Radial
Engine
1.
INDUCTION
(SUCK)
o Even
cylinder
cooling
o High
drag
profile
• The
above
diagram
is
enclosed
by
2
o Hydraulicing
still
an
issue
• Pressure
decreases
on
the
down
stroke.
adiabatic
and
2
isochoric
lines.
• Horizontally
Opposed
• Higher
pressure
outside
induces
the
fuel
/
o Adiabatic
–
No
heat
transfer
o Saves
space
air
mixture
into
the
cylinder.
(compression
&
power)
o Good
visibility
o Isochoric
–
Constant
volume
(intake
o No
hydraulicing
problems
2.
COMPRESSION
(SQUEEZE)
and
exhaust)
• Ideally
the
maximum
pressure
occurs
when
CONTANT
/
INTERMITTENT
PROCESS
• Volume
decreases,
so
pressure
and
combustion
is
complete.
temperature
both
increase.
• Power
output
is
intermittent
(only
on
power
stroke)
• Combustion
is
at
constant
volume
and
3.
POWER
(BANG)
varying
pressure.
• Mixture
is
ignited.
• Temperature
increases
rapidly
for
a
short
time
then
decreases
for
the
rest
of
the
stroke.
• Pressure
increase
pushes
the
piston
down.
4.
EXHAUST
(BLOW)
• Piston
rises
and
pushes
exhaust
gases
out.
• A.K.A
Scavenging
, ENGINES
3
–
PISTON
ENGINE
CONSTRUCTION
CRANKCASE
CRANKSHAFT
CONNECTING
ROD
• Houses
the
crankshaft
• Converts
reciprocating
linear
motion
to
• Connects
the
piston
to
the
crankshaft.
• Supports
the
cylinders
rotary
motion
and
transmits
engine
torque
• Connected
to
the
piston
at
the
little
end
via
a
• Provides
mounting
for
engine
accessories
to
the
propeller.
Gudgeon
Pin
(or
Piston
/
Wrist
Pins)
• Forms
an
oil
tight
chamber
• Usually
made
of
alloy
steel.
o Fully
floating
to
prevent
uneven
wear
• Usually
made
of
aluminum
alloy
• Oil
is
passed
into
the
main
journal
and
is
• A
crankcase
breather
prevents
a
pressure
transferred
to
the
big
end
journals
which
build
up
inside
the
crankcase.
are
rotating.
• One
cycle
per
720
degrees
of
crank
rotation
• Stroke
=
Distance
the
piston
moves
through
• Throw
=
Distance
from
main
to
big
end
journal
=
½
Stroke
PISTON
CRANK
ASSEMBLY
• Usually
made
of
aluminum
alloy.
• Crankshaft
• Top
Compression
Ring
o Gas
tight
fit
and
reduces
friction.
• Connecting
Rods
o Usually
made
of
chromium
steel.
• Pistons
o Spring
out
of
the
groves
as
the
cylinder
wears.
• 2
Compression
Ring
nd
o Seals
+
scrapes
oils
• Oil
Control
Ring
o Distributes
oil
and
helps
scrape
it
back
to
the
crankcase.
1
–
BASIC
GAS
LAWS
BOYLE’S
LAW
TRANSFER
OF
HEAT
• Assumes
constant
temperature
• Conduction
• Product
of
pressure
and
the
volume
is
• Convection
constant
providing
temperature
of
the
gas
• Radiation
remains
unchanged.
• P1
V1
=
P2
V2
CHARLE’S
LAW
• Assumes
temperature
is
varied.
• With
constant
pressure,
if
temperature
increases
then
volume
must
increase.
• P1
/
T1
=
P2
/
T2
• With
constant
volume,
if
temperature
increases
then
pressure
must
increase.
• V1
/
T1
=
V2
/
T2
GENERAL
GAS
EQUATION
• All
three
statements
combined
!! !! !! !!
• !!
= !!
, ENGINES
2
–
LAWS
OF
MOTION
NEWTONS
FIRST
LAW
FORCE
THRUST
CALCULATION
• A
body
at
rest
will
remain
at
rest
and
a
body
• Force
=
Mass
x
Acceleration
• F
=
m
x
a
in
motion
will
continue
in
uniform
• SI
Unit:
N
(Newton)
𝑊
𝐹 = × 𝑎
(direction
and
speed)
motion
unless
it
is
• Imperial
Unit:
lbsf
(Pounds
force)
𝑔
acted
on
by
an
outside
force.
• Weight
of
airflow
through
propeller
is
800
lbs/s,
the
inlet
velocity
is
0
ft/s
and
the
DENSITY
outlet
velocity
is
160
ft/s.
Calculate
thrust?
NEWTONS
SECOND
LAW
• Thrust
is
a
force
so
equation
above
is
used.
• Density
=
Mass
/
Volume
• The
acceleration
produced
in
a
mass
by
the
• Varies
with
temperature
and
pressure
800
application
of
a
force
is
directly
𝐹 = × 160 = 4000 𝑙𝑏𝑠𝑓
32.20
proportional
to
the
force
and
inversely
proportional
to
the
mass.
• F
=
m
x
a
MOMENTUM
• Momentum
=
Mass
x
Velocity
NEWTONS
THIRD
LAW
INERTIA
• To
every
action,
there
is
an
equal
and
opposite
reaction.
• Tendency
of
a
body
to
preserve
its
state
of
rest
or
uniform
motion.
WEIGHT
AND
MASS
• Weight
is
the
force
with
which
the
gravity
of
the
earth
attracts
a
mass.
• W
=
m
x
g
• Accel
due
gravity:
32.20
ft/s2
or
9.81
m/s2
, ENGINES
3
–
PISTON
ENGINE
CONSTRUCTION
BASIC
PRINCIPLE
VOLUME
&
PRESSURE
RELATIONSHIP
TYPES
OF
ENGINES
• Convert
linear
to
rotary
motion.
• In-‐Line
Engine
o Poor
cockpit
visibility
• Inverted
In-‐Line
Engine
4
STROKE
CYCLE
o Improved
visibility
o Suffers
from
hydraulicing
(turning
over
• A.K.A
The
Otto
Cycle
before
start
is
required).
• Radial
Engine
1.
INDUCTION
(SUCK)
o Even
cylinder
cooling
o High
drag
profile
• The
above
diagram
is
enclosed
by
2
o Hydraulicing
still
an
issue
• Pressure
decreases
on
the
down
stroke.
adiabatic
and
2
isochoric
lines.
• Horizontally
Opposed
• Higher
pressure
outside
induces
the
fuel
/
o Adiabatic
–
No
heat
transfer
o Saves
space
air
mixture
into
the
cylinder.
(compression
&
power)
o Good
visibility
o Isochoric
–
Constant
volume
(intake
o No
hydraulicing
problems
2.
COMPRESSION
(SQUEEZE)
and
exhaust)
• Ideally
the
maximum
pressure
occurs
when
CONTANT
/
INTERMITTENT
PROCESS
• Volume
decreases,
so
pressure
and
combustion
is
complete.
temperature
both
increase.
• Power
output
is
intermittent
(only
on
power
stroke)
• Combustion
is
at
constant
volume
and
3.
POWER
(BANG)
varying
pressure.
• Mixture
is
ignited.
• Temperature
increases
rapidly
for
a
short
time
then
decreases
for
the
rest
of
the
stroke.
• Pressure
increase
pushes
the
piston
down.
4.
EXHAUST
(BLOW)
• Piston
rises
and
pushes
exhaust
gases
out.
• A.K.A
Scavenging
, ENGINES
3
–
PISTON
ENGINE
CONSTRUCTION
CRANKCASE
CRANKSHAFT
CONNECTING
ROD
• Houses
the
crankshaft
• Converts
reciprocating
linear
motion
to
• Connects
the
piston
to
the
crankshaft.
• Supports
the
cylinders
rotary
motion
and
transmits
engine
torque
• Connected
to
the
piston
at
the
little
end
via
a
• Provides
mounting
for
engine
accessories
to
the
propeller.
Gudgeon
Pin
(or
Piston
/
Wrist
Pins)
• Forms
an
oil
tight
chamber
• Usually
made
of
alloy
steel.
o Fully
floating
to
prevent
uneven
wear
• Usually
made
of
aluminum
alloy
• Oil
is
passed
into
the
main
journal
and
is
• A
crankcase
breather
prevents
a
pressure
transferred
to
the
big
end
journals
which
build
up
inside
the
crankcase.
are
rotating.
• One
cycle
per
720
degrees
of
crank
rotation
• Stroke
=
Distance
the
piston
moves
through
• Throw
=
Distance
from
main
to
big
end
journal
=
½
Stroke
PISTON
CRANK
ASSEMBLY
• Usually
made
of
aluminum
alloy.
• Crankshaft
• Top
Compression
Ring
o Gas
tight
fit
and
reduces
friction.
• Connecting
Rods
o Usually
made
of
chromium
steel.
• Pistons
o Spring
out
of
the
groves
as
the
cylinder
wears.
• 2
Compression
Ring
nd
o Seals
+
scrapes
oils
• Oil
Control
Ring
o Distributes
oil
and
helps
scrape
it
back
to
the
crankcase.
