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Simulating The SuperCobra
CSC 1992
SUBJECT AREA Aviation
			EXECUTIVE SUMMARY
Title:  Simulating the SuperCobra
Author:  Major William R. Liston, United States Marine Corps
Thesis:  The SuperCobra  is a  complicated and  expensive
aircraft  that  requires  "hands-on"  training.  Therefore,
greater use of flight simulators for pilot training will lower
operating costs,  increase pilot proficiency, and save war-
fighting assets.
Background:  The Cobra is a complicated aircraft in which
cockpit coordination is critical to safe flight.   Tandem-
seating prevents crew-members from sharing cockpit duties and
requires the assignment of specific responsibilities between
the two crew-members.  Poor design is a major problem making
pilot  training  an  enormous  task  difficult  to  measure
quantitatively.   Complete training of a Cobra pilot  is a
prolonged process  and  requires  considerable  instruction.
Unfortunately,  for Marine Corps Cobra pilots, all  flight
training must be conducted in the actual aircraft.   Flight
simulators, although expensive, have training costs far less
than "real" aircraft training and can provide more in-depth
training. Today, advanced computers, motion bases, and visual
systems, have contributed considerably to creating an almost
real world feel to flying a simulator.  By placing greater
emphasis on simulation, the air wing can have an effective,
cost saving method of familiarizing a pilot with the rigors of
flying in high risk environments without jeopardizing an
aircraft or aircrew.
Recommendation:  The Marine Corps needs to place greater
emphasis on training systems in order to save scarce resources
and provide quality training.
	SIMULATING THE SUPERCOBRA
		      OUTLINE
Thesis:  The SuperCobra  is a  complicated and  expensive
aircraft that requires hands-on training.  Therefore, greater
use of simulators for military pilot training will  lower
operating costs, increase pilot proficiency, and save war-
fighting assets.
I.	Historical anecdote
	A.	Cobra accident
	B.	Pilot Error
II.	Pilot Training
	A.	Brief history of the AH-1
	B.	Human factors
	C.	Aerodynamics of helicopters
	D.	Physiological stresses
	E.	Mission of the AH-1
III.	Weapons and tactics
	A.	Air to ground munitions
	B.	Training and readiness flights
	C.	Qualifications
	D.	Ordnance requirements
IV.	Simulators
	A.	Types
		1.	CPT
		2.	WST
		3.	Combat mission simulator
	B.	Real-time defined
V.	The AH-1W WST
	A.	Description
	B.	Digital control loading
	C.	Capabilities
	D.	Visual system
	E.	Motion System
	F.	Limitations
	G.	Procedural errors cost war-fighting assets
	H.	Cutbacks in defense spending
	I.	Cost effectiveness
		SIMULATING THE SUPERCOBRA
     The Cobra attack helicopter, with a crew of two, departed
from Camp Pendleton on a typical summer evening in Southern
California; the sky ablaze with sunset.  Enroute to perform a
routine training flight, the aircraft, now on it's second
mission of the day, had just refueled without incident. The
pilot in command(PIC) was a highly regarded aviator with over
3,000 flight hours.  The co-pilot, new to the squadron, was
progressing through the flight syllabus. This training flight
required the pilot under instruction (PUI) to occupy the rear
seat while the instructor pilot (IP) occupied the front; but
this training flight never arrived at the training area.  When
the aircraft failed to report in, a search was initiated by
the Operations Duty Officer.  Coincidentally, as the search
party was being formed, a forest ranger was reporting a fire
in the mountains: the black smoke of a helicopter crash.  When
the accident board reached the crash site, both pilots were
dead.  Due to the extensive fire damage, the accident board
was not able to determine the cause of the accident, however,
it was obvious the helicopter had come apart upon impact.  The
accident board had several theories about the cause of the
crash, but the single theory that kept surfacing was the
possibility of an engine fire or engine failure.   If this
theory was correct, why had the accident investigators found
the fire handle of the "good engine" in the "pulled" position?
In an emergency, pulling the fire handle of the "affected
engine," shuts off fuel to the burning engine.  Speculation by
the review board concluded that perhaps the PUI had pulled the
wrong fire handle during the immediate action steps of the
emergency procedure, cutting off fuel to the "good engine."
Without fuel to the "good engine" all power was lost,   the
main rotor lost RPM, airspeed and altitude were lost, and the
aircraft could not be recovered.   The conclusion of  the
accident board:  PILOT ERROR.
     Although it seems like fiction, this story is true.  Two
irreplaceable pilots, an expensive aircraft, and the cohesion
of an entire squadron gone.  Could additional training have
prevented this calamity?  Possibly, however the Cobra is a
very complicated aircraft in which cockpit coordination is
critical to safe flight.  Cockpit coordination, essential to
all aircraft, is an integral part of mission success in the
Cobra.  Tandem-seating prevents crew-members from sharing
cockpit  duties  and  requires  the  division  of  specific
responsibilities between the two crew-members.  Poor cockpit
design,  another major  problem,  makes  pilot  training  an
enormous task difficult to measure quantitatively.  Therefore,
training a Cobra pilot becomes a prolonged process requiring
considerable instruction.   Unfortunately, for Marine Corps
Cobra pilots, all flight training must be conducted in the
actual aircraft.  Attack helicopter pilots never get enough
tactical flying experience or practice weapons delivery to
sharpen combat skills.   The result of inadequate pilot
training increases risk of damage, loss of aircraft, and pilot
death.  To insure the highest level of proficiency in the air,
standardized pilot instruction should take place on the ground
and not in the complex stressful environment of the aircraft.
The SuperCobra is a complicated and expensive aircraft that
requires "hands-on"  training.  Therefore, greater use of
flight simulators for pilot training will  lower operating
costs,  increase pilot proficiency,  and save war-fighting
asset.
     The problems arising from inadequate pilot training are
not new.  Tracing the development of the Cobra and the advent
of its weapons system trainer requires a brief history.  The
first attack helicopter was a modified UH-1 Iroquois, known as
the "helicopter gunship."  The "helicopter gunship" became a
formidable weapon in Vietnam and lead to the development of
the "Cobra." Tandem-seating, the major difference between the
Iroquois and the Cobra, streamlined the Cobra's design making
it faster and less visible.  Greater firepower was added to
the Cobra with the installation of a 20mm gun turret and
dedicated wing stations to support 2.75 inch rockets.   In
1965, the aircraft, designated AH-1G HueyCobra (a name derived
from its predecessor the UH-1 Iroquois),  made  its  first
flight.   In 1967, the Marine Corps acquired 38 "G" models
while awaiting delivery of its successor; the twin-engine AH-
1J SeaCobra.  The delivery of eighty-four AH-1J SeaCobras to
the Marine Corps included two  "J" models to be used as
prototypes for the improved SeaCobra designated the AH-1T.
The "T" model had a slightly stronger engine package, a new
transmission, and a massive rotor system.   To fulfill the
anti-armor mission, the Marines converted the "T" models into
the AH-1T (TOW) by adding the TOW Missile System.  By 1986,
the AH-1T had been re-designed and re-introduced to the Marine
Corps as the AH-1W dubbed, the "Whiskey."  The "Whiskey" was
equipped with a General Electric T-700 engine package, a
Heads-up Display, and the Hellfire Modular Missile System
(HMMS), making the Whiskey the most potent member of the Cobra
family.
     Despite twenty years of historical changes, there is one
area where Cobra designers have fallen short and complicated
the aircraft even further.  The designers have overlooked the
human factor, the relationship between man and machine.  At
first glance into the Cobra cockpit the lack of human factors
engineering  is evident  (Illustration 1).   All  emergency
handles and switches are  in the rear seat.   During an
emergency the pilot must direct his attention away from flying
the aircraft in order to complete "immediate action" emergency
procedures.  To further complicate responsibilities, the rear
Click here to view image 
seat pilot must also monitor communication, navigation and
organize weapons systems.  The primary function of the co-
pi lot (front-seat pilot) is control of the TOW missile, and
the twenty-millimeter gun.  Limited flight is possible from
the front seat, however the location and size of the flight
instruments make flying difficult.  The front cockpit is small
and does not permit installation of backup emergency panels or
switches (Illustration 2).
     Learning to fly the SuperCobra is an enormous challenge
to the novice pilot.   Unlike an airplane,  the helicopter
derives it's lift from a rotary wing.  "Lift generation by a
'rotating wing'  enables  the helicopter to accomplish its
unique mission of hovering motionless in the air, taking off
and landing in confined or restricted area, and autorotating
to a safe  landing following a power  failure."   (9:399)
Constant  motion  of  the  rotor  system,  and  the  dynamic
environment in which it operates, creates two distinct problem
areas:  vibration and instability.  Vibration is the feed-back
of the main-rotor translated through the airframe to the seat
and flight controls.  In a study conducted by the National
Aeronautics and Space Administration they report, " Noise and
vibration  probably  cause  fliers  more  inconvenience  and
annoyance than any other factor in flight.  Both undoubtedly
have an important part in producing headaches, visual and
auditory fatigue, airsickness, and the general discomfort
experienced  at  the  end  of  a  long  flight."    (5:2-21)
Generally, after a two hour flight helicopter pilots are
exhausted  and  fatigued.  Instability, a derivative of
vibration, is another hardship which the Cobra pilot must
tolerate.  The SuperCobra, like many helicopters, does not
maintain balanced flight without the aid of the pilot.  The
pilot must therefore constantly manipulate the flight controls
throughout the mission.
     After the new pilot has acquainted himself with twenty
years of changes,  learned to tolerate  the lack of human
factors engineering, grasped understanding of the dynamics of
helicopter flight (including the fatigue it produces), he must
then wade his way through the complex mission requirements of
the Cobra.   During the sixties, the mission of the attack
helicopter was:  armed escort, and fire support.  The greatest
threat,  to the Cobra, was a rifleman or  the occasional
surface-to-air missile.  Today, the mission of the Supercobra
includes:  armed escort, close-in fire support, ground convoy
escort, armed reconnaissance, anti-armor, visual reconnais-
sance, artillery and naval gunfire spotting, anti-radiation,
and defensive air-to-air maneuvering.  Threat systems against
the Cobra have become significantly more lethal.   Armored
vehicles have laser designators, surface to air missiles are
widespread, and anti-helicopter aircraft are easily available.
Consequently, these improved threats have forced the Cobra to
operate under the cover of darkness, augmented by Night Vision
Goggles (NVG), to insure mission success.
        The SuperCobra accomplishes these missions and tasks
using a variety of weapons and special flying techniques.
During routine missions, the weapons most frequently used are
the 20mm cannon and 2.75 inch rockets.  The TOW and Hellfire
guided missiles  are  used  for  anti-armor  and  air-to-air
engagements are flown with the AIM-9 Sidewinder missile. The
latest weapon in  the Cobra arsenal  is the Sidearm anti-
radiation missile.  To take advantage of terrain masking,
maneuverability and relative speed,  SuperCobra's fly much
closer to the earth than fixed wing aircraft.  Helicopter
pilots rely on motion and visual cues to maintain terrain
clearance.  Depending upon the type of threat, there are three
flight profiles used by attack helicopters:  contour, low-
level,  and nap-of-the-earth  (NOE).  These unique flight
profiles and ordnance loads require extensive training and are
the focus of the problems which plague the Cobra pilot.  The
Training and Readiness manual (Vol.3) addresses the quantity,
and type of munitions (Table 1) required for:
     1.	Basic and transition pilot
     2.	Conversion pilot
     3.	Refresher pilot
     4.	Instructor pilot
Click here to view image 
Cobra flight training is further divided into qualification
standards.  Pilot qualification is conducted in a three stage
instruction.  The first stage, Combat Ready Training, includes
Formation, TERF, Navigation, air-to-ground, escort, and NVG.
Combat Qualification, the second stage addresses electronic
warfare, tactics, and supporting arms coordination.  In the
final stage of  training, carrier qualification and field
carrier landings are refined, ultimately leading to full-
combat qualification.
     Eighty-four training flights are required to "qualify a
Cobra pilot."  Of these, thirty-three flights require the
delivery of ordnance.  The re-fly factor (a time-sensitive
interval which relates to currency) of some flights may have
an interval as short as fifteen days while others may take as
long as a year.  Usually, the flights with short training
intervals are associated with high risk/stress missions.  The
most stressful high risk mission flown by Cobra pilots is the
night vision goggles ordnance flight in support of assault
support helicopters.  The cost of maintaining pilot profi-
ciency is astounding.  The amounts in Table 1 represent annual
requirements but, due to the distribution and allocation of
ordnance throughout an aircraft group, many pilots fail to
meet the minimum requirements for "currency."
     Meeting pilot training requirements should not have to be
subject to distribution and allocation availability.  Annual
flight training should include instruction in an approved
simulator according to the Training and Readiness Manual.
Unfortunately, the Marine Corps Cobra community does not have
a functional device to supplement flight training and, to the
determent of  the Marine Corps, some view simulators as
expensive video games.
     However, simulators are not expensive video games, they
are complex, invaluable training devices that take years to
develop.  There are several types of training devices that are
presently available to supplement military pilot training.
Simple cockpit models, often referred to as cockpit procedures
trainers (CPT) or part-task trainers, are useful in learning
cockpit layout and refining emergency procedures; however,
they lack the feel of flight.  The "whole-task," operational
flight trainer (OFT) or weapons systems trainer (WST) is more
expensive and requires an extensive computer system to imitate
the "real aircraft." Computer systems are modeled to match the
flying qualities of  the aircraft and  joined to a motion
system.  Lacking artificial intelligence, the WST is a poor
second to the combat mission simulator.
     The combat mission simulator is the most expensive and
complex of all training devices.  These trainers have the
capability of dynamic interface with artificial intelligence
and other combat mission simulators.  Dynamic interface allows
two different units, in separate geographic locations,  to
train simultaneously in the same artificial environment.  The
combat mission simulator is currently operational on the AH-64
Apache.
     New training devices incorporate  "real-time" dynamic
interface between the flight control system, computer, and
visual system.  Current state-of-the-art military simulators
incorporate dynamic threats allowing pilots to venture into
threat  environments.  Undoubtedly,  realistic  interaction
between an aircrew under instruction and a threat simulation
is the best form of training for building confidence and
experience without risking scarce war-fighting assets.
     The Marine  Corps,  after  more  than  eight  years  of
development is currently putting the finishing touches on the
Whiskey weapons system trainer.  The AH-1W Supercobra weapons
system trainer  (WST)  is  a dual-cockpit  simulator  system
(Illustration  3)  produced  by  CAE  LINK,  Houston,  Texas
(Formerly SINGER LINK).  Each housed separately, the pilot
(rear seat) and co-pilot/gunners (front seat) cockpits both
include onboard instructor stations permitting simultaneous
independent training or combined joint-crew training in an
integrated mode.  Both cockpits are mounted on a six-degree-
of-freedom motion system (Illustration 4).  A visual system
completely encircles each station and provides the visual cues
necessary for effective and realistic flight training.  The
pilot's  station provides  training for normal  procedures,
Click here to view images
emergency procedures,  navigation,  and  offensive/defensive
tactics. The Copilot/gunner station provides similar training
however emphasis is placed on weapons system operation.
     To accomplish  standardized  training,  the  instructor
becomes the pivotal connection between the simulator and the
trainee.  The instructor's responsibilities include overseeing
the  brief,  establishing  the  simulated  conditions,  and
monitoring the progress of the PUI.  The simulator contains
state-of-the-art components as the basis for the instructional
system.  Digital control loading is the key feature to "flying
the simulator."  "The Control Loading System exists to produce
feel  forces,  on  the  simulator's  flying  controls,  which
accurately reflect those felt by the pilot in actual flight
conditions.   In order to achieve this it is necessary to
produce the correct feel force gradients throughout the entire
control range of the subject aircraft."  (13:77)   Another
feature of the trainer also includes an automatic flight
control mode that  contains  a record/playback feature  to
measure  performance.    As  an  example,  the  pilot  under
instruction  can  fly  a profile  (an  instrument  approach,
Illustration 5)  that  is compared  to  a set  of  standard
criteria.  When he completes the maneuver, the instructor can
re-play the profile and de-brief trouble spots.  The student
can re-fly the procedure, practicing proper technique, until
the maneuver becomes instinctive.
Click here to view image
     Visual systems are extremely important for realistic
interpretation of the landscape.  Photo-based texture models
and high speed computers are making the visual environment
more realistic.  Photographs of terrain features are digitized
and blended with shading into the simulated visual scenes.  The
combination of computer graphics and photo-based texture
models enhance the realism of the picture.  A similar process
can be used when training for combat engagements.  Image
generators can manipulate Defense Mapping Administration (DMA)
data to reproduce three dimensional representations of actual
terrain.  When the scene is properly modeled, threat systems
with dynamic interaction  (artificial  intelligence) can be
placed in the scene.  Combining the capabilities of the host
computer (Illustration 6) and visual computer simulated combat
missions  can  be  flown  in  this  threat  representative
environment.
     The motion system, primarily controlled by the pilot, Is
the last key element of the trainer.   As the pilot makes
control input, the host computer signals an hydraulic system
to direct the platform movement.  The hydraulic legs extend
and retract giving the pilot the sensation of movement.  Not
all weapons system trainers are required to move as a result
of control input.  There are training devices with fixed based
mounting instead of an hydraulic motion system (C-130, F-18,
F-14, AV-8B).  With proper pilot input, the visual environment
Click here to view image
moves as the seat and cockpit remain in a fixed position.  The
force of gravity  (G-forces)  in  this  type of  trainer  is
simulated with a G-seat.  G-seats are specially manufactured
aircraft seats that use inflatable air cushions to press the
body against the seat belt and shoulder harness to create the
feeling G-forces.
     The inter-relationship between the host computer, visual
image generator, and the motion system cannot be over-stated.
Training devices cannot be expected to create every situation
and to perform every function.  Design errors can translate
into negative training and learning which can be transferred
into the real aircraft.  As an example, some experienced
pilots become ill when flying a trainer due to system up-dates
from the host computer to the motion system.  As the pilot
moves the flight controls, there is a slight delay referred to
as "transport delay." It cannot be seen by the eye, but the
inner ear and unconscious mind can sense the difference.
Frequently the time difference causes experienced pilots to
become physically ill and disoriented or, as referred to in
the flying community, "getting a case of the leans."
     Flight simulators,  although expensive,  have  training
costs far less than "real" aircraft training.   "Aircraft
capital, operating, and maintenance costs are high.  To use an
aeroplane for training can incur added cost.  For example,
training in emergency procedures such as aborting a take-off
may involve additional maintenance and replacement component
cost." (13:234) Simulators can provide more in-depth training
than can be accomplished in the aircraft.  Although the basic
concepts of flight remain the same, advanced computers, motion
bases, and visual systems have contributed considerably to
creating an almost real world feel to simulators.  Also, there
is a very high percentage of  transfer learning from the
simulator  to  the  aircraft  which  can  be  quantitatively
measured.
     Technological advances in the past twenty five years have
made the modern battlefield a lethal environment for aircraft.
Demands on a pilot during combat engagements are stressful and
often  create  situations  where  procedural  errors  are
inevitable.  In combat, a mistake or procedural error can be
the difference between life and death. Although simulation is
still in it's infant stages, improvements and engineering
breakthroughs continue to make modern training systems capable
of many tasks inconceivable a few short years ago.  The use of
flight simulators for sharpening military pilot skills will
continue to increase as government spending is cut-back from
military training programs. Today, with training devices like
the Cobras weapons system trainer, training opportunities,
previously limited or waived, can be conducted, repeated, and
measured.  By placing greater emphasis on simulation, Marine
Corps aviation can have an effective, cost saving method of
familiarizing a pilot with the rigors of flying in a high risk
environment without jeopardizing an aircraft or aircrew.
			BIBLIOGRAPHY
1.	Berbaum, K.S., and R.S. Kennedy.  Visual Tasks In
Helicopter Shipboard Landing. Iowa City: University of Iowa,
1991.
2.	Caro, Paul W., Oran B. Jolley, Robert N. Isley, and Robert
H. Wright. Determining Training Requirements In Fixed Wing Aviator
Training. Alexandria:  Human Resources Research Organization, 1972.
3.	Comptroller General of the United States. Greater Use of
Flight Simulators In Military Pilot Training Can Lower Costs and
Increase Pilot Proficiency. Washington D.C.. Department of Defense,
1973.
4.	Duffy, John O., and Carroll M. Colgan. A System of Flight
Training Quality Control and Its Application to Helicopter Training.
Alexandria:  George Washington University, 1963.
5.	Hamilton, John G., and Eric Peterson. Aerospace Science:
The Science of Flight. Maxwell: Airforce J.R.O.T.C., 1988.
6.	Hoover, Stewart V., and Robert F. Perry.  Simulation A
Problem-Solving Approach. New York: Addison-Wesley Publishing
Co., 1989.
7.	Hufford, Lyle, and Jack Adams. The Contribution of Part
Task Trainers to the Relearning of a Flight Maneuver.  New York:
U.S. Training Device Center, 1961.
8.	Hurst, Ronald, and Leslie Hurst, eds. Pilot Error The Human
Factors.  New York: Janson Aronson, Inc., 1982.
9.	Hurt, H. H. Jr. Aerodynamics For Naval Aviators.  Washington
D.C.:  Office of the Chief of Naval Operations Aviation Training Division,
1965.
10.	Kelly, Lloyd L., as told to Robert B. Parke. The Pilot Maker.
New York:  Grosset and Dunlap, 1970.
11.	Krendell, Ezra S., and Joel W. Bloom. The Natural Pilot Model
For Flight Proficiency Evaluation.  New York:  U.S. Naval Training Device
Center, 1963.
12.	Prophet, Wallace W. Human Factors in Air Mobility.  Alexandria:
Human Resources Research Organization, 1969.
13.	Rolfe, J.M.,and K.J. Staples, eds.  Flight Simulation.  New York:
Cambridge University Press, 1986.
14.	Saunders, George.  Dynamics of Helicopter Flight.  New York:
John Whiley and Sons Inc., 1975.
15.	Whiskey.  Houston:  Bell Helicopter Textron, 1988.
			GLOSSARY
ANVIS.   Aviator's Night Vision Imaging System.  Night vision
goggles specifically designed for use In aircraft.
ARTIFICIAL INTELLIGENCE.  Computer generated responses
which duplicate human interaction with the computer system.
CPT.  Cockpit procedures trainer.
COMBAT MISSION SIMULATOR.  A state-of-the-art simulator
which contains  artificial  intelligence  that  responds  to  human
interaction.
COMPUTER-GENERATED IMAGERY.  Visual images produced
by means of  computer image generation.
CONTOUR FLIGHT.  Flight at low altitude which conforms
generally and in proximity to the contours of the earth's
surface.
CONTROL LOADING.  A system using stroke hydrostatic hydraulic
actuators controlled through a servo valve and linked to the flight
control levers.  The model includes spring gradient, breakout forces
and artificial feel systems in addition to cable characteristics, friction
and the inertia of non-present aircraft parts.
CURRENCY.  The training interval between mission specific flights
without which training may not proceed.
DATA LINK.  A communication link suitable for transmitting data.
FIELD OF VIEW.  The horizontal and vertical subtended angles
of the boundaries of a CGI window as measured at the eyepoint.
FIXED-BASE.  A stable platform on which a training device sits
without moving.
FORWARD AIR CONTROLLER (AIRBORNE).  An air controller
airborne in the area of operations in a helicopter of  fixed-wing
aircraft.  His  primary  function  is  the  detection  and destruction
of enemy targets in both the close and deep battle.
G-SEAT.  A specially designed cockpit seat that incorporates
air cells and accelerometers that inflate as a function of control
loading.
HELICOPTER GUNSHIP.  A name given the UH-1 during the Vietnam
war as a result of the gun and rocket pods that were mounted
on the airframe.
HMMS.  Hellfire modular missile system.  A laser guided anti-
tank weapon.
HOST COMPUTER.  A part of the simulator complex which solves
equations of motion, accepts inputs from the flight crew or operator,
drives displays and interfaces with visual system and motion base
systems.
HUD.  Head-up display.
HUMAN FACTORS.  A scientific approach to the interaction
between a man and a machine.
IMAGE GENERATOR.  A computer system designed to reproduce
a visual scene.
IP.  Instructor pilot.
LINK TRAINER.  The first pilot training simulator.
LOW-LEVEL.  Flight conducted at a selected altitude at which
detection and observation of the aircraft or of the points
which, or to which, it is flying are avoided or minimized.
MODEL.  Similar  likeness  of  the  same  aircraft  that
incorporates change.
mm.   millimeter.
MOTION SYSTEM.  A hydraulic platform capable of moving in
response to a given input.
NAP-OF-THE-EARTH.  Flight as close to the earth's surface as
vegetation and obstacles permit while generally following the
contours of the earth's surface.
OFT.  Operational Flight Trainer.
PIC.  Pilot in command.
PROFICIENCY.  The measure of competence of a given task.
REAL-TIME.  Groups of software modules designed to be iterated
by a computer at  a rate which  is  selected to suit  the simulation
task.  The capability of a computer to calculate a response to an
input within one second or less.
SCENE.  The approximation of a real world visual environment
the observer sees at any given moment while looking through
specified windows on a simulator.
SEA COBRA.  A name given to the Marine Corps model of the
AH-I.
SEAT SHAKER.  A device designed to vibrate a seat in response
to rotor dynamics, and pilot inputs.
SIDEARM.  A sidewinder anti-radiation missile.
SIDEWINDER.  A close in air-to-air missile.
SIMULATION. The process of designing a mathematical or logical
model of a real system and then conducting computer-based
experiments with the model to describe, explain, and predict
the behavior of the real system.
STABILITY.  The  inherent ability of a body to maintain
equilibrium.
TANDEM-SEATING.  Fore and aft arrangement of pilot cockpits.
TERF.  Terrain flight.
THCDP.  Tow-Hellfire Control Display Panel.
TOW.  Tube-launched optically tracked wire guided missile.
TRANSPORT DELAY.  The delay caused by the amount of time
required  to  propagate  a  signal  from  a  time-corrected
(extrapolated) control input from the host computer to the
last picture element of the most recently updated field or
frame.
WST.  Weapons System Trainer.



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