<s>
A	O
flight	B-Application
simulator	I-Application
is	O
a	O
device	O
that	O
artificially	O
re-creates	O
aircraft	O
flight	O
and	O
the	O
environment	O
in	O
which	O
it	O
flies	O
,	O
for	O
pilot	O
training	O
,	O
design	O
,	O
or	O
other	O
purposes	O
.	O
</s>
<s>
Flight	B-Application
simulation	I-Application
is	O
used	O
for	O
a	O
variety	O
of	O
reasons	O
,	O
including	O
flight	O
training	O
(	O
mainly	O
of	O
pilots	O
)	O
,	O
the	O
design	O
and	O
development	O
of	O
the	O
aircraft	O
itself	O
,	O
and	O
research	O
into	O
aircraft	O
characteristics	O
and	O
control	O
handling	O
qualities	O
.	O
</s>
<s>
The	O
term	O
"	O
flight	B-Application
simulator	I-Application
"	O
may	O
carry	O
slightly	O
different	O
meaning	O
in	O
general	O
language	O
and	O
technical	O
documents	O
.	O
</s>
<s>
In	O
more	O
recent	O
definitions	O
,	O
this	O
has	O
been	O
named	O
"	O
full	O
flight	B-Application
simulator	I-Application
"	O
..	O
</s>
<s>
The	O
more	O
generic	O
term	O
"	O
flight	B-Application
simulation	I-Application
training	O
device	O
"	O
(	O
FSTD	B-Application
)	O
is	O
used	O
to	O
refer	O
to	O
different	O
kinds	O
of	O
flight	B-Application
training	I-Application
devices	I-Application
,	O
and	O
that	O
corresponds	O
more	O
closely	O
to	O
meaning	O
of	O
the	O
phrase	O
"	O
flight	B-Application
simulator	I-Application
"	O
in	O
general	O
English	O
.	O
</s>
<s>
The	O
"	O
Tonneau	O
Antoinette	O
"	O
(	O
Antoinette	O
barrel	O
)	O
,	O
created	O
by	O
the	O
Antoinette	O
company	O
,	O
seems	O
to	O
be	O
the	O
precursor	O
of	O
flight	B-Application
simulators	I-Application
.	O
</s>
<s>
The	O
best-known	O
early	O
flight	B-Application
simulation	I-Application
device	O
was	O
the	O
Link	O
Trainer	O
,	O
produced	O
by	O
Edwin	O
Link	O
in	O
Binghamton	O
,	O
New	O
York	O
,	O
United	O
States	O
,	O
which	O
he	O
started	O
building	O
in	O
1927	O
.	O
</s>
<s>
The	O
Link	O
Trainer	O
was	O
a	O
basic	O
metal	O
frame	O
flight	B-Application
simulator	I-Application
usually	O
painted	O
in	O
its	O
well-known	O
blue	O
color	O
.	O
</s>
<s>
Some	O
of	O
these	O
early	O
war	O
era	O
flight	B-Application
simulators	I-Application
still	O
exist	O
,	O
but	O
it	O
is	O
becoming	O
increasingly	O
difficult	O
to	O
find	O
working	O
examples	O
.	O
</s>
<s>
The	O
result	O
was	O
that	O
the	O
USAAF	O
purchased	O
six	O
Link	O
Trainers	O
,	O
and	O
this	O
can	O
be	O
said	O
to	O
mark	O
the	O
start	O
of	O
the	O
world	O
flight	B-Application
simulation	I-Application
industry	O
.	O
</s>
<s>
The	O
Celestial	O
Navigation	O
Trainer	O
of	O
1941	O
was	O
13.7m	O
(	O
45ft	O
)	O
high	O
and	O
capable	O
of	O
accommodating	O
the	O
navigation	O
team	O
of	O
a	O
bomber	B-Application
crew	O
.	O
</s>
<s>
In	O
1954	O
United	O
Airlines	O
bought	O
four	O
flight	B-Application
simulators	I-Application
at	O
a	O
cost	O
of	O
$3	O
million	O
from	O
Curtiss-Wright	O
that	O
were	O
similar	O
to	O
the	O
earlier	O
models	O
,	O
with	O
the	O
addition	O
of	O
visuals	O
,	O
sound	O
and	O
movement	O
.	O
</s>
<s>
This	O
was	O
the	O
first	O
of	O
today	O
's	O
modern	O
flight	B-Application
simulators	I-Application
for	O
commercial	O
aircraft	O
.	O
</s>
<s>
Most	O
flight	B-Application
simulators	I-Application
are	O
used	O
primarily	O
for	O
flight	O
training	O
.	O
</s>
<s>
With	O
more	O
advanced	O
displays	O
,	O
cockpit	O
representation	O
and	O
motion	O
systems	O
,	O
flight	B-Application
simulators	I-Application
can	O
be	O
used	O
to	O
credit	O
different	O
amount	O
of	O
flight	O
hours	O
towards	O
a	O
pilot	O
license	O
.	O
</s>
<s>
During	O
the	O
aircraft	O
design	O
process	O
,	O
flight	B-Application
simulators	I-Application
can	O
be	O
used	O
instead	O
of	O
performing	O
some	O
flight	O
tests	O
.	O
</s>
<s>
Such	O
"	O
engineering	O
flight	B-Application
simulators	I-Application
"	O
can	O
provide	O
a	O
fast	O
way	O
to	O
find	O
errors	O
,	O
reducing	O
both	O
the	O
risks	O
and	O
the	O
cost	O
of	O
development	O
.	O
</s>
<s>
Flight	B-Application
simulators	I-Application
may	O
include	O
training	O
tasks	O
for	O
crew	O
other	O
than	O
pilots	O
.	O
</s>
<s>
The	O
lowest	O
level	O
of	O
helicopter	B-Application
flight	B-Application
simulator	I-Application
.	O
</s>
<s>
These	O
definitions	O
apply	O
to	O
both	O
airplanes	O
and	O
helicopters	B-Application
unless	O
specified	O
otherwise	O
.	O
</s>
<s>
Training	O
devices	O
briefly	O
compared	O
below	O
are	O
all	O
different	O
subclasses	O
of	O
Flight	B-Application
simulation	I-Application
training	O
device	O
(	O
FSTD	B-Application
)	O
.	O
</s>
<s>
Flight	B-Application
simulators	I-Application
are	O
an	O
example	O
of	O
a	O
human-in-the-loop	O
system	O
,	O
in	O
which	O
interaction	O
with	O
a	O
human	O
user	O
is	O
constantly	O
happening	O
.	O
</s>
<s>
As	O
military	O
aircraft	O
often	O
need	O
to	O
cooperate	O
with	O
other	O
craft	O
or	O
military	O
personnel	O
,	O
wargames	B-Application
are	O
a	O
common	O
use	O
for	O
distributed	O
simulation	O
.	O
</s>
<s>
Some	O
examples	O
include	O
SIMNET	B-General_Concept
,	O
DIS	B-Operating_System
and	O
HLA	B-Operating_System
.	O
</s>
<s>
Flight	B-Application
simulators	I-Application
typically	O
do	O
n't	O
include	O
full	O
computational	O
fluid	O
dynamics	O
models	O
for	O
forces	O
or	O
weather	O
,	O
but	O
use	O
databases	O
of	O
prepared	O
results	O
from	O
calculations	O
and	O
data	O
acquired	O
in	O
real	O
flights	O
.	O
</s>
<s>
To	O
achieve	O
good	O
transfer	O
of	O
skills	O
,	O
there	O
are	O
very	O
specific	O
requirements	O
in	O
the	O
flight	B-Application
simulator	I-Application
regulations	O
that	O
determine	O
how	O
closely	O
they	O
must	O
match	O
the	O
real	O
aircraft	O
.	O
</s>
<s>
These	O
requirements	O
in	O
case	O
of	O
full	O
flight	B-Application
simulators	I-Application
are	O
so	O
detailed	O
,	O
that	O
it	O
may	O
be	O
cost-effective	O
to	O
use	O
the	O
real	O
part	O
certified	O
to	O
fly	O
,	O
rather	O
than	O
manufacture	O
a	O
dedicated	O
replica	O
.	O
</s>
<s>
Vibration	O
actuators	O
may	O
also	O
be	O
included	O
,	O
either	O
due	O
to	O
helicopter	B-Application
simulation	O
requirements	O
,	O
or	O
for	O
aircraft	O
equipped	O
with	O
a	O
stick	O
shaker	O
.	O
</s>
<s>
Displaying	O
them	O
on	O
a	O
screen	O
is	O
sufficient	O
for	O
the	O
most	O
basic	O
simulators	O
and	O
amateur	B-Application
flight	I-Application
simulation	I-Application
,	O
however	O
most	O
classes	O
of	O
certified	O
simulators	O
need	O
all	O
buttons	O
,	O
switches	O
and	O
other	O
inputs	O
to	O
be	O
operated	O
in	O
the	O
same	O
way	O
as	O
in	O
the	O
aircraft	O
cockpit	O
.	O
</s>
<s>
Because	O
of	O
these	O
reasons	O
,	O
there	O
is	O
ongoing	O
research	O
on	O
interactions	O
in	O
virtual	B-Application
reality	I-Application
,	O
however	O
lack	O
of	O
tactile	O
feedback	O
negatively	O
affects	O
users	O
 '	O
performance	O
when	O
using	O
this	O
technology	O
.	O
</s>
<s>
Similarly	O
,	O
since	O
helicopters	B-Application
can	O
perform	O
hover	O
flight	O
in	O
any	O
direction	O
,	O
some	O
classes	O
of	O
helicopter	B-Application
flight	B-Application
simulators	I-Application
require	O
even	O
180	O
degrees	O
of	O
horizontal	O
field	O
of	O
view	O
.	O
</s>
<s>
Because	O
the	O
screen	O
is	O
much	O
closer	O
than	O
objects	O
outside	O
aircraft	O
,	O
for	O
simulators	O
with	O
multiple	O
pilots	O
,	O
there	O
are	O
special	O
collimated	O
displays	O
that	O
eliminate	O
the	O
parallax	B-Device
effect	O
between	O
the	O
pilots	O
 '	O
point	O
of	O
view	O
.	O
</s>
<s>
An	O
alternative	O
to	O
large-scale	O
displays	O
are	O
virtual	B-Application
reality	I-Application
simulators	I-Application
using	O
a	O
head-mounted	B-General_Concept
display	I-General_Concept
.	O
</s>
<s>
Real-time	O
computer	O
graphics	O
visualisation	O
of	O
virtual	O
worlds	O
makes	O
some	O
aspects	O
of	O
flight	B-Application
simulator	I-Application
visual	O
systems	O
very	O
similar	O
to	O
game	O
engines	O
,	O
sharing	O
some	O
techniques	O
like	O
different	O
levels	O
of	O
details	O
or	O
libraries	O
like	O
OpenGL	B-Application
.	O
</s>
<s>
Recent	O
scientific	O
studies	O
have	O
shown	O
that	O
the	O
use	O
of	O
technology	O
such	O
as	O
vibration	O
or	O
dynamic	O
seats	O
within	O
flight	B-Application
simulators	I-Application
can	O
be	O
equally	O
effective	O
in	O
the	O
delivery	O
of	O
training	O
as	O
large	O
and	O
expensive	O
6-DOF	O
FFS	O
devices	O
.	O
</s>
<s>
The	O
largest	O
flight	B-Application
simulator	I-Application
in	O
the	O
world	O
is	O
the	O
Vertical	O
Motion	O
Simulator	O
(	O
VMS	O
)	O
at	O
NASA	O
Ames	O
Research	O
Center	O
,	O
south	O
of	O
San	O
Francisco	O
.	O
</s>
