Rochester Institute of Technology
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Thesis/Dissertation Collections
2-19-1992
The design and construction of a hang glider flight
simulator
Kim L. Sherman
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Recommended Citation
ROCHESTER
INSTITUTE OF TECHNOLOGY
A Thesis Submitted
to theFaculty
ofThe
College
ofFine
andApplied
Arts
in
Candidacy
for
theDegree
ofMASTER
OF FINE ARTS
THE DESIGN AND CONSTRUCTION OF
A HANG GLIDER FLIGHT SIMULATOR
By
KIM
L SHERMAN
TABLE OF CONTENTS
LIST
OF ILLUSTRATIONS
iv
GLOSSARY OF TERMS
vINTRODUCTION
1
Chapter
1
.AN
OVERVIEW
OF HANG GLIDER CONSTRUCTION
AND
CONTROL
2
Construction
Control
Stalls
Launch
andLanding.
2.
THE
THE NEED FOR HANG GLIDER FLIGHT
SIMULATION
7
The
current state ofhang
gliding
instructionNovice
Instruction.Current
attempts athang
gliderflight
simulation.Common
errors ofbeginning
studentsLeaping
into
the air.Reversed
turn response.Pivoting
around center ofgravity
rather thanshifting
weightfor
a turn.HUMAN FACTORS
17
Considerations
in
developing
aHang
Glider
Flight
Simulator.
Degree
ofSimulation: How
many
aircraftcharacteristics are present
in
the simulator?Fidelity: How
accurately
does
the simulatorreproduce
the
experience offlying
the aircraft?Transfer: How
much of whatis learned
on thesimulator
is
usedin
a realflight
situation?Cost
Effectiveness.
Instructional Considerations.
THE FINAL DESIGN
20
Effective for
training.Basic
configuration.Pitch
control.Stall
simulation.Roll/Yaw
control.Take-off
andlanding.
Ease
of operation.Flight
simulationfor
the student.Flight
simulationfrom
theinstructor's
point of view.
Portability
and assembly.Portability.
Assembly.
Non-threatening
attractive appearance.The
Name.
Appearance.
Safe
to
use.Low
cost manufacturing.THE
COMPUTER AS
A TOOL FOR
INDUSTRIAL DESIGN
41
CAD.
Rendering.
CONCLUSION
45
WORKS CITED
48
LIST
OF
ILLUSTRATIONS
Figure
Page
1
.HANG GLIDER
3
2.
AXES OF ROTATION
4
3.
THE GOONEY BIRD TRAINER HANG GUDER FLIGHT
SIMULATOR
22
4.
DIVE POSITION
23
5.
STALL
POSITION
24
6.
LAUNCH POSITION
28
7.
NORMAL FLIGHT POSITION
30
8.
LANDING
STALL
31
9.
LANDING APPROACH
33
10.
THE
GOONEY BIRD TRAINER ASSEMBLY
35
11.
LOADING THE COUNTERWEIGHTS
36
12.
COMPUTER RENDERING
,4213.
THE COMPLETED PROTOTYPE
47
GLOSSARY
OF
TERMS
AIRSPEED
-Speed
ofthe
glider relativeto
the air.ANGLE OF ATTACK
The
angle ofthe
wing
relative to thedirection
of motion throughthe
air.DEGREE
OF SIMULATION
-The
number of a particular operational aircraft's characteristicsthat
are presentin
a simulator.FIDELITY
-The
accuracy
with which a simulator reproduces the experience offlying
the operational aircraft.GROUNDSPEED
-Speed
ofthe glider relativeto the ground.
LAMINAR AIR FLOW
Smooth
layers
ofairmoving
past a wing.LIFT
-Laminar
airflow past an airfoil
creating
alow
pressure area above the wing.OPERATIONAL AIRCRAFT
-The
actual aircraft that a simulator
is intended
represent.PITCH
-Rotation
of an aircraft around
its lateral
axisraising
orlowering
the nose.RIDGE LIFT
-Wind
flowing
up
over ahill
or ridge.ROLL
Rotation
ofan aircraft aroundits longitudinal
axisraising
onewing
andlowering
the other.STALL
-Occurs
when the wing's angle of attackis increased
to the point that thelaminar
airflowbecomes
turbulent and nolonger
produceslift.
THERMAL
A
column ofrising
hot
air.TRANSFER
-The
use of skillslearned
on a simulator tofly
operational aircraft.INTRODUCTION
Hang
gliding
is
probably
the
closest a person can come toexperiencing
bird-like flight.
Unfortunately,
the
precise skills needed tofly
ahang
glider aredifficult
to
teach throughdemonstration
or verbalinstruction.
Consequently,
many
people'sfirst
few
flights
are awkward and sometimesdangerous.
A
hang
gliding
student'sfirst flight
is
a soloflight,
so control errors areunderstandable.
However, every
effort mustbe
made to minimize theseerrors.
Classroom instruction
abouthang
glider aerodynamics and controlis
helpful,
but
thefirst
time
the student'sfeet
leave
the ground the classroomlessons tend
to getleft behind.
What is
neededis
some meansfor
the studentto gain
hands-on
flying
experience prior to thefirst
training
flight.
This
need prompted me todevelop
theGooney
Bird
Trainer,
ahang
gliderflight
simulatorthat willimitate
ahang
glider's pitch, roll andyawcharacteristics
in
response to a student's control movements.The
simulatorwill also allow students
to
practicethe launch
andlanding
sequences.To
understandfully
thethinking
behind
thedesign
of the simulator, acursory understanding
ofhang
glider construction and control as well as anintroduction
to the process ofhang
gliding
instruction
are presented.This
thesis alsoincludes
asummary
of relevanthuman
factors
studies.Because
virtually
no researchhas been done
involving hang
glidersimulators,
it
wasnecessary
to usethe
available research about traditional aircraftsimulators.
CHAPTER
1
AN
OVERVIEW
OF HANG
GLIDER
CONSTRUCTION
AND CONTROL
Construction
A
hang
glideris
afoot launched
motorless aircraft.The
pilotis
suspendedin
aharness from
a single attachment point near the center ofthe glider.In
flight,
the
harness
supportsthe
pilotin
a prone position.The
glideris
constructed of a Dacron sailcloth on a rigid aluminum
frame.
Several
ribsrunning
from
thefront
to theback
ofthewing giving
it its
airfoil shape(fig. 1 ).
Control
There
are no control surfaces(ailerons,
stabilizers,flaps
or rudder).The
only moving
"part"
on a
hang
glideris
the pilot.The
glideris
controlledby
thepilot
changing
body
position relative to the airframe of the glider,thereby
changing
the apparent center ofgravity
of the glider.Rotating
an aircraft aroundits longitudinal
axisis
called roll, rotationaround
its lateral
axisis
called pitch, and rotation aroundits
vertical axisis
called yaw
(fig. 2).
By
pulling
back
on thefixed
controlbar,
the pilot's weightis
actually
forced forward
toward the nose ofthe glider.The
changein
thepilot's position
lowers
the nose(pitch)
resulting
in
anincrease in
speed.Pushing
the pilot's weight to one sidelowers
thatwing
(roll)
andinitiates
a5
By
shifting
toward the
rear ofthe
gliderthe
pilot canactually
gain a smallamount of altitude.
However,
the
gliderquickly
loses
air speedcausing
thewing
to stall.Stalls
Laminar
airflow
overthe
wing
produceslift.
If
thewing's angle of attackis
too great
(such
as whenflying
tooslowly)
the smoothlaminar
airflow becomes
turbulent
and thewing
nolonger
produceslift.
This is
called a stall.Hang
gliders aredesigned
tobe
inherently
stable.This
means that agliderthat
is
flying
tooslowly,
diving,
orturning,
has
abuilt-in
tendency
toreturn to straight and
level
flight
and resume an appropriateflying
speed.A
stall will
automatically
be
followed
by
adive in
orderfor
the gliderto pickup
flying
speed.The
more severe the stall, the more severe thedive
thatfollows.
The
inherent
stability
ofhang
gliderdesign is
a positivefeature
but it
cannot prevent a stall
from
occurring.Stalls
at altitudes of more than1
00 feet
rarely
present a problembecause
thereis
enough room to recover.Low
altitude stalls,
however,
are the number one cause of accidents andinjury
in
hang
gliding.This is
especially
truefor
beginning
studentswho,beginning
with their
first flight
andin
closeproximity
to the ground, mustlearn
aboutpitch control, air speed and stalls.
In
thedive
following
alow
altitude stall, the glider acceleratestoward
theground.
Usually,
the
hang
glider takes thebrunt
ofthe impact.
The
control6
glider
into
the
ground.(Small
wheels mounted onthe
bottom tube
ofthecontrol
bar
can savethe
student'sknuckles.)
At
this point the glider willstop
abruptly
but
the
pilotwill not.Usually
one ofthe
down tubes
ofthe controlbars
willbe
bent
asthe
student pilot swingsforward
through the controlbar.
In
more severe crashesthe
studentmay
break
an arm.In
rare casesit is
possible
for
the studentto
sustainhead injuries
by
swinging
forward
forcefully
enough to strike the
forward
section ofthekeel.
Needless
to say, properpitch control
is
animportant
skill tolearn.
Launch
andLanding
During
launch,
the glideris
supported on the pilot's shoulders.By
running
down
agently sloping
hill
with the glider at the correct angle ofattack, thepilotwill gain enough airspeed within a
few
steps tolift into
the air.Launch
sites are
typically
onhills
that are500"
or more above the
surrounding
terrain.Once
in
the air, the pilot must changefrom
the uprightrunning
position tothe prone
flying
position.On
mostharnesses
thisinvolves
leaning
forward
into
theharness
andplacing
thefeet
into
an attachedstirrup
for
support.The
landing,
of course requires the pilot tostep
out ofthestirrup
and pushup into
the upright position.Just
priortotouching
down the
pilot must pushthe
controlbar
forward
tobring
the nose ofthe gliderup into
a stall positionCHAPTER
2
THE NEED FOR
HANG GLIDER
FLIGHT SIMULATION
The
Current State
ofHang Gliding
Instruction
Novice Instruction.
A typical
hang
gliding
coursefor
beginning
pilots variesgreatly among
schools.Nearly
all schools provide a ground school(classroom
instruction)
and actualflight instruction.
The
ground schoolmay
takeanywhere
from
30
minutes to severalhours.
It
oftenincludes instruction
onglider
construction, set-up,
aerodynamics and groundhandling.
Flight instruction is
normally
a gradual progression andmay vary
in length
between
onehour
to severaldays,
depending
on the particular program.The
studentbegins
by
making
several practice runs with the glider onlevel
ground to
become
accustomed torunning
with thehelmet,
harness
andglider.
If
properly
executed, the glider will gain enough airspeed tofloat up
offthe student's shoulders,
imitating
thefirst
phase of a takeoff run.Once
theinstructor is
confidentthat the studentis
ready, a takeoff runis
madefrom
part
way up
a small gentle slope.The
additional speed generatedby
running
down
the slope allows the gliderto produce morelift.
Additional
runs aremade
from higher
on thehill
until the studentis
able tobecome
airborne.Initial
training
flights
aretypically
very
short,little
more than a take-offfollowed
by
alanding.
As
theflight
instruction progresses, the studentlaunches from higher
points on thetraining
hill.
As
theflights
getincreasingly
longer
the studentis
required to make minor turn corrections tokeep
theglider
flying
straight.Longer
flights
allow the pilotto
practice gentle turns.Current
attempts athang
gliderflight
simulation.Few
hang
gliding
schoolsmake use of
any
kind
offlight
simulator.Typically,
the simulators that are usedconsist of
nothing
more than a controlbar
andharness
statically
suspendedfrom
afixed
structure.The
studentwill move the controlbar
toturn,
and theinstructor
will rotatethe
student on the suspensionline
to approximate theeffect of
the
controlinput.
If
the student pushes out on the controlbar,
theinstructor
canonly
describe
verbally
that this would cause the glider to gainaltitude,
lose
speed andeventually
stall.In
spite of the gradual progression of theinstruction
process,many
hang
gliding
students are still overwhelmedby
themany
new sensationsduring
afirst
flight.
Consequently,
there are a number of common errors madeby
novice students that could
easily
be
correctedby
use of a realisticflight
simulator.
Common Errors
ofBeginning
Students
Leaping
into
the air.There
is
abrief
periodduring
the take-off run thatthe glider
lifts itself
up
offthe student's shouldersbut is
not yettraveling
fast
enough to
lift
the weight ofthe student.The
studentfeels
the gliderlifting
into
the air and not
wanting
tobe left
behind,
leaps
into
the air.Since,
the gliderdoes
not yethave
adequate airspeed tolift
the weight of the student,both
the student and glider
drop
abruptly
to the ground.Students
mustlearn
to9
Reversed
turn response.The
steering
controlin
nearly any
kind
ofvehicle requires
the
operator to move the controlin
thedesired direction
ofturn.
A
hang
glider,
however,
requires that the student's weightbe
pushedin
thedesired direction
ofturn,
meaning
that
the student must push the controlbar
tothe
left to
make a right turn.This
control movementis
not anintuitive
response andfrequently
resultsin
studentsreversing
their turn responses at criticaltimes
during
training
flights.
At
a time when a gentleleft
turn
is
required,
the studentmay
make a gentle right turn.Believing
that thewind
has blown
themfurther
off course, the student pilotmay
respondby
making
an evenharder
right turn rather than the appropriateleft
turn.Pivoting
around center ofgravity
rather thanshifting
weightfor
a turn.Traveling
head
first
in
the prone positionis
also a new and unnaturalexperience
for
most people.It
takes time tolearn
exactly
where thebody
is
located in
space.Frequently,
the resultis
errorsin
turning.To
make a rightturn,
a student must pullhimself
to the right side ofthecontrol
bar.
Because
hang
glider pilots are suspendedfrom
a single point,students often make the mistake of
pivoting
around their center ofgravity
rather than
actually shifting
their weight.The head
moves to the right andthe
feet
move to theleft.
The
studentfeels
that thenecessary
controlmovement was made to
initiate
asharp
right turn andis
shocked tofind
that the glideris
stillheaded
straightfor
a tree.Over-control.
High
aspect ratio wings(long
andslender)
are most10
they
are controlledby
weight-shift ratherthan
controlsurfaces,
they
do
notrespond
immediately
tothe
pilot's roll control movements.There is
a slightdelay
before
the
gliderbegins
to respond.There is
a seconddelay
periodwhile
the
glideris
actually rolling
into
the
desired
position.These
twodelay
periods are called the
primary
andsecondary
response times.Students
respond tothe
movements ofthe glider.When
the studentinitiates
a turn andnothing
happens
immediately,
it is
a natural response topush the control
bar
alittle
bit
moreresulting
in
over control.The high
aspect ratio oftoday'shang
gliders also means thatthey
arevery
shortfrom front
toback
making
the pitch controlextremely
responsive.Because
the controlinput
requiredfor
pitch and roll arevery
different,
it
canbe
quite a taskfor
the
student to coordinate the two.The
most commonerror of
beginning
studentsis low
altitude stalls causedby
over-reacting
onCHAPTER 3
HUMAN
FACTORS
Considerations
in
Developing
a
Hang
Glider Flight Simulator
All
ofthe
available research onflight
simulators pertains to simulators oftraditional
aircraft.Even though there
are obviousdifferences
(instrumentation,
military
applications,
etc.),many
ofthe physical sensationsand
learning
theories
are relevant tohang
gliding
as well.As
a result ofmy
research, I
found
thatany
discussion
offlight
simulatorsmust
include
aninvestigation
of allfactors
involved in
thetraining
processincluding
the student, theinstructor,
theflight
characteristics oftheoperational aircraft, the simulator, and the
training
objectives.The
threeprimary
reasonsfor
using
a simulator are:1
)
greater controloverthe
flight
conditions that the student encounters,2)
lower
risk comparedto the actual operational situation and,
3)
reducedtraining
costs(Willigies
1973),
(Valverde 1973).
The
safety
issue is
probably
the greatest concernfor
hang
gliding
schools since the
hang
gliding
student'sfirst flight is
a soloflight.
Hang
gliderflight
simulatorsmay
make a significant contribution towardpreparing
studentsfor
this
first flight.
Other benefits
ofhang
glidersimulatorsinclude:
theability
to train at night or
during
inclement
weather, and publicdemonstrations
in
any
location.
12
Some
important
considerationsin
developing
a simulator that warrantfurther
discussion
are:degree
ofsimulation,
fidelity,
transfer,
costeffectiveness,
andinstructional
considerations.Degree
ofSimulation: How
many
aircraft characteristics are presentin
thesimulator?
During
the
course of aflight,
a pilot oftraditional aircraft gathersgeneral
flight information
through visual cues, airspeedmay
be determined
by
listening
tothe
air asit
moves past,kinesthetic
cues canindicate linear
acceleration,
and the pilot's vestibular sensedetects
angular(rotational)
acceleration
(Jacobs 1973).
Because
hang
glider pilots usefew if
any
instruments,
they
mustrely
heavily
on these same physical cues.It
wasdiscovered in
researchfor
traditional simulators thatkinetic
cuing
improved
performancein landings
and other ground referencedtraining
(Povenmire
1973),
(Willigies
1973),
(Valverde 1973).
This
means that a pilot'sphysical sensation ofthe pitch, roll and yaw motion of the aircraft provides
information
thatis
usefulin
flying
the aircraft.Two
types ofmotion cues canbe
built into
simulatordesign:
maneuvermotion and
disturbance
motion. Maneuver motionis
pilotinduced
andrepresents the aircraft's response to pilot
input.
Disturbance
motionrepresents environmental
factors
such as turbulence or aircraft mechanicalproblems.
Two
characteristics ofhang
glidersillustrate
a needfor both
disturbance
and maneuver cues
in
hang
gliding
simulators.First,
when airturbulencelifts
one
wing
(disturbance
motion), a pilot can respond much morequickly
to the13
learn
this skillin
a simulatoris
adefinite benefit.
Secondly,
because
oftheunique construction of
hang
gliders,
roll control requiresthat
the controlbar
be
moved tothe
left
for
a rightturn,
andto
the rightfor
aleft
turn,
just
theopposite of most other
types
of vehicles a studentmay
have
experienced.This is
a common and critical source of confusionfor
hang
gliding
students.A
simulator with maneuver motion provides
the
studentwithimmediate
feedback
as tothe
appropriateness ofthe
controlinput.
Visual
simulationis
essentialfor
ground-referenced controlin
any
simulator(Willigies 1
973),
but
thisis
especially
truefor
hang
gliders since thereis
neveran option
for
aninstrument
landing.
The
visual cuesfor
landing
arehelpful
primarily
for
indicating
ground speed, altitude and rate ofdescent.
Flying
ahang
glider requires that a pilot respond to visual,kinetic
andauditory
cues.If
these cues are thehelpful
in
flying
an actualhang
gliderthen,
asfar
as practical,they
shouldbe
representedin
the simulator.Fidelity: How
accurately
does
the simulator reproduce the experience offlying
the
aircraft?The
perfecthigh
fidelity
simulatordesign is
not possible,necessary, or even
desirable.
First,
it
is
not possiblefor
a simulator toduplicate
the range of motion of an aircraft.The
most that canbe duplicated
is
the initial
acceleration.However,
thisinitial
accelerationis
avery
strong
physical stimulus and one ofthe more
important
cuesfor
evoking
animmediate
and appropriate responsefrom
the student.Since
theprimary
purpose ofthe simulator
is training,
thereis
no needfor
ahang
gliderflight
simulatorto
imitate
motionbeyond
thatwhich a pilotis
normally
ableto14
Kinesthetically,
thehuman
body
has
noway
ofperceiving
straight-lineconsistent motion.
The
body
perceives accelerations only.The
motion of anelevator
is
felt
only
asthe
elevatoris
starting
orstopping, no motionis felt
while
moving
between floors.
Consistent
motionis
perceived through thevisual sense only.
There is
no need tophysically
simulate motions that arebelow the
student's vestibular andkinesthetic
thresholds for
acceleration sincethey
can'tbe
perceived.Once
the initial
accelerationhas
ended, mosthigh-end simulators return to the neutral position at a subliminal rate to prepare
for
the next required movement.
This design
feature
is
called washout(Hopkins
1975),
(Lintern 1980).
To
simulate a rightturn,
a typical aircraft simulator wouldimitate
the initialrolling
motion.The
visualimage
would continuetheillusion
ofthe turn as thesimulator
gently
returned to neutral.To
pull out oftheturn,
the simulatorwould roll
left
asthe
visualimage
returned tolevel
(relative
to the pilot).The
simulator would
then,
once againgently
rollback
to neutral.The
mechanismsnecessary
todesign
washoutinto
a simulatorwouldbe
too expensiveto
incorporate
into
ahang
gliderflight
simulator.Excluding
thisfeature
from
thedesign
is
not a significant problem since theprimary
objectivefor
beginning
hang
glider studentsis
to maintain straight andlevel
flight.
The
instructor
can move the simulatorfrom
theintended "flight
path"
and require
the student return
it
to the neutral position.Effective
visual cues aretypically
accomplished with simple animatedperspective
line drawings
produced on one or moreCRT's
(Willigies
1973),
15
that
provideboth
visual and motioncuing
is
the
difficulty
in
avoiding
any
delay
between
the twodifferent
types of cues(Blaiwes
1973).
With
a1
0" to 12"range of motion, a
hang
glider simulator capable ofpitch,roll and yaw movements
in
direct
responseto student controlinput
willprovide most of the visual and motion
cueing necessary
for
training.The
onecue
that
is
not providedby
such a simulatoris
forward
motion.Maintaining
the appropriate airspeed
is
thebest
meansfor
avoiding
stalls.The
sound ofthe air
rushing
pastthe pilot and glideris
thebest indicator
of airspeed.During
actualtraining
flights
groundspeedis
the strongest visual cuefor
forward
velocity
andis
closely
associated with air speed.Groundspeed,
however,
is
not a reliableindicator
of airspeed.A
gliderwith a groundspeedof
20
mph,flying
in
the samedirection
as a1 5
mph wind willhave
anairspeed of
5
mph andconsequently
be in
afull
stall.As
a result, visual cuesfor
ground speed are of questionable valuein
ahang
glider simulator andmay
even reinforce poorhabits.
Auditory
cuesfor
airspeed are more
important,
less
costly
and should,therefore, be
incorporated into
thedesign
if
possible.Though
it
is
occasionally
disputed,
abasic
premise of simulatordesign
is
that the greater the
similarity
between thetraining
and operational situations,the greater the transfer
(Adams 1979).
As
mentioned earlier, the threeprimary
benefits in
using
flight
simulators as opposed to operational aircraftfor
training
are reduced cost, reduced physical riskto the student, and theinstructor's increased
control over thetraining
task.Generally
speaking, the16
control the
instructor has
over the situation(A
hang
gliderflight
simulatorwith
1
00%
fidelity
wouldbe
ahang
glider).The
realdifficulty
lies
in
determining
the optimumbalance
between the
simulatorbenefits
andsimulator
fidelity.
Transfer: How
much of whatis
learned
on the simulatoris
usedin
a realflight
situation?Transfer is
akey
considerationin
simulatordesign.
The
cost,safety
and convenience of a simulator are oflittle
consequenceif
none ofthetraining
is
transferred to the operational situation.Under
most circumstances,there appears to
be
astrong
correlationbetween high
fidelity
andhigh
transfer
(Adams 1
979),
but
thisis
not always the case.Other
instructionalfactors
weighheavily
in
thefacilitation
of transfer.It is
possiblefor
effectivetransfer to occur with a
very
simplemockup
(Adams 1979).
Conversely,
it
is
possiblefor
avery
elaborate simulator to producenegative transfer.
If
non-realistic motionis
presentin
the simulator, thestudent
may
learn
to respond to motion thatdoesn't
existin
the operationalaircraft
(Willigies 1973).
The
method ofinstruction
whenusing
arelatively
simplehang
gliderflight
simulator
is
very
important.
Fidelity
willbe limited
by
cost constraints.Visual,
auditory
and motion systemswillbe
only
crude approximations ofreality
compared to the multi-million
dollar
simulators usedfor
many
oftoday'ssophisticated aircraft.
The
hang
glider simulator shouldbe
usedonly
toacquire the
basic
skillsnecessary
for
a safefirst
flight
or to correct arecurring
17
an "accomplished" simulator pilot, much of what was
learned
may
have
tobe
unlearned
to
fly
ahang
glider.Cost
Effectiveness.
Aside from
safety, the
main reasonfor
using
asimulator
for traditional
aircrafttraining
is
thatit
is
more cost effective thantraining
on operational aircraft.However,
thereis
a pointin
simulatortraining
when, eventhough
the studentis
stilllearning,
transfer nolonger
occurs at a
high
enough rate tobe
cost effective.To
use a simulatorbeyond
this point
is
consideredover-training
(Blaiwes
1973).
Though
the cost ofoperating
ahang
glideris
a smallfraction
of whatit
costs
for
traditional aircraft, thebasic
principleis
the same.The
greatest costfactor in
using
ahang
gliderfor
training
comesfrom
thehigh
risk of minor,but
costly, damage
during
a student'sfirst few
flights.
A bent
controlbar
orleading
edge tube can costbetween
$20
and$80.
This
mustbe
weighedagainst the cost ofthe
instructor's
time whileteaching
with the simulator.At
some point transferwill
become
minimal or negative transferwillbecome
significant enough
to
warranttermination of a student's simulator training.Instructional Considerations.
There
arefive
important instructional
considerations that should
be incorporated into
simulator training.1
)
Knowledge
of resultsIf
the studentis
tolearn
anything,feedback
mustbe
given as to the appropriateness of
the
student'sbehavior
(Adams 1979).
The
more
immediate, direct,
andlogical
thefeedback,
thebetter.
Verbal
praise ordirection from
theinstructor
is
helpful but
it
isn't
nearly
as effective ordirect
asthe objective and
immediate
feedback from
arelatively
high
fidelity
hang
18
2)
Identical
elements vs. cognitivelearning
-Some
researchers contend
that
the transfer oftraining
is
greatest when thetraining
taskand the operational task are most alike.Others believe
that
transfer shouldbe
produced
by
any
meansthat
develop
the mental process requiredfor
dealing
with the operational task(Blaiwes
1973),
(Adams 1979).
An
appropriate solution will
probably
be
a combination ofthe two.A
hang
glider simulatorthat
is
slightly
moredifficult
tofly
than an actualhang
glidermay
better
prepare the student pilotfor
flying
ahang
glider.3)
Stimulus
- responselearning
"If
a responseis
tobe
made to a stimulus,then the stimulus and the control
for
response toit
mustbe in
thesimulator"
(Adams
1
979).
Ideally
ahang
gliderflight
simulator shouldbe
able to simulatedrifting
offtheintended
flight
path, excessive andinadequate
speed, and a stall.The
simulator shouldbe
able torepresent these characteristics
during
thelaunch,
flight,
orlanding
phase.If
the student pilot responds correctly, the simulator shouldreturn to a simulation ofstraight and
level
flight.
4)
Student
motivation and acceptance-The
student mustbe
motivatedand the
training
shouldbe
a source of motivation(Hopkins 1 975).
People learn
tofly
hang
glidersfor
enjoyment.The
simulator should reduceanxiety
and risk.It
should give the neophyte a preview of thefun
to come.5)
The simulatordoes
not train the student-The
entiretraining
program(student,
instructor,
curriculum andtraining
environment)
mustbe
19
important
than thedesign
characteristics ofthe
simulatoritself.
The
simulator
is
not an essential toolfor flight training,
but
soundinstruction
is (Blaiwes
1973),
(Caro
1973).
The
hang
glider simulator needs tobe
designed
as a part of a system notsimply
as a machine thatimitates
CHAPTER
4
THE FINAL
DESIGN
Six
fundamental
design
objectives were establishedearly
in
thedesign
process.
These
objectives represent the characteristics of an optimalhang
gliding
flight
simulator :1
)
Is
an effective toolfor training.
2)
Is
easy
to
operatefor
theinstructor
as well as the student.3)
Is
easy
totransport
and set up.4)
Possesses
anon-threatening
attractive appearance.5)
Presents
nothreat
to thesafety
of the students orinstructor.
6)
Is
low
cost,low
volume manufacturing.This
chapterdescribes how
and to what extentmy
prototypehang
gliderflight
simulator, theGooney
Bird
Trainer,
meets these sixdesign
criteria.Effective for
Training
If the
studentsdon't benefit from
using
the simulatorthereis
little
pointin
using
it.
The
goal was todesign
ahang
gliderflight
simulatorthat wouldenable a student to practice
four
essentialflying
skills priorto thefirst
flight:
the
take-off,
straight andlevel
flight,
gentleturns,
and thelanding.
Basic configuration.
The basic design
ofthe simulatoris
a10"
lever
armattached to the
top
of a 10' tripod.A
hang
glider controlbar
is
attached to21
one end of the
lever
arm.A
studentwearing
ahang
gliding
harness
is
suspended
inside
the controlbar.
An
adjustable counterweight at the otherend
balances
the student's weight(fig.
3).
The
connectionbetween
thelever
arm and
tripod
is
atwo
axis pitch,roll,
and yawjoint (PRY
joint)
thatwasdeveloped
for
this
simulator.This joint is
instrumental in
simulating
pitch, roll,and yaw motions.
The
horizontal
axis allowsfor
simulated pitch movement.The
second axisis
nearly
vertical and allowsfor
the simulation ofthe roll/yawmovement.
Pitch
control.By
moving
forward
through the controlbar
the studentmoves
away
from the fulcrum (horizontal
axis).The
center ofgravity
ofthelever
armis
moved toward the student which causes the simulator tolower
the student a
distance
thatis
proportional to the control movement.The
downward
motion simulates the pitchdown
andloss
of altitude experiencedduring
adive (fig. 4).
Conversely, moving
back
through the controlbar
causes the simulator to raise the student.
The
upward motion simulates themoderate altitude gain and
pitching
up
experienced prior to a stall(fig. 5).
The
simulator produces realistic motionin
response to the student's controlmovements through
approximately
90 of pitch (45up
ordown).
Stall
simulation.The
simulatoritself
is
notdesigned
to simulate stalls,although there
is
the potentialfor
adding
thisfeature in future designs.
The
mechanism needed to
physically
andrealistically
simulate a stall wouldbe
relatively
complex and add considerable cost to the simulator.The benefits
Fig.
3
THE GOONEY
BIRD TRAINER
25
As
mentionedin
chapterthree,
adevice
such as a noise generatormay
contribute to stall simulation
by
indicating
airspeed.In
an actualhang
gliderthe
best
indicator
of airspeedis the
sound ofthe airmoving
pastthe
gliderand pilot.
The
volume ofthe
noise generator wouldincrease
in
adive
anddecrease
to
nothing
in
a stall.The
varying
volume would provide studentswith an
important
auditory
cuefor
avoiding
andrecovering
from
stalls.Roll/Yaw
control.Roll
and yawarelinked in
the simulatorbecause
rollcontrol
is
theway
in
whichthe
studentinitiates
a turn(yaw)
in
an actualhang
glider.
The
nearly
vertical roll/yaw axis of thePRY
joint
is
key
to the roll/yawresponse ofthe simulator.
As
the student shifts to the right, atwisting
force is
applied to the
lever
arm.Because
the roll/yaw axisis
leaning
back
slightly
from
vertical, the resultantforce
moves the pilot to the right.The
simulator produces realistic motionin
response to the student's controlmovements through
approximately
45of yaw (22.5
left
or right).High
banked
or sustained turns cannotbe
realistically
simulated.This is
oflittle
consequence
however
since thebeginning
studentis
concernedprimarily
with
maintaining
straight andlevel
flight
ormaking
gentleturns.Not
allhang
glider motionis
pilotinduced.
Breezes
and airturbulence willcontinually
change theheading
ofthe gliderif
the pilotdoesn't
makecorrections.
This is
animportant
skillfor
students todevelop
during
simulatortraining.
A
mechanicallink between
the instructor and thelever
arm canbe
used to simulate wind-induced yaw.
The
current simulator prototype,the
Gooney
Bird
Trainer,
uses a rope as theinstructor link
andis
quite effectivein
26
Take-off
andlanding.
The
take-off andlanding
procedures are specialcases
because
the
pilotis
very
close tothe
ground and must respond to thegliders air
speed,
groundspeed,
and altitude accordingly.The
Gooney
Bird
Trainer is
capable ofproviding
rather crude simulations of ahang
glider'sresponse
during
take-off
andlanding.
For this
reasonthe
basic
skillsnecessary
for
pitch and roll control can and shouldbe
learned
during
normalflight
simulation rather than
during
the
take-offandlanding
phases.The
simulatoris
still able to assistin
the correction of some common errors madeduring
thetake-offand
landing
phases.The transition between
the vertical and prone pilotpositions,
andgetting
the
feet
into
and out oftheharness
are some ofthe more critical skills tobe
learned
during
the take-off andlanding
phases offlight
simulation.The
control
bar is
usedby
the
pilot to pushinto
the upright position and pulldown
into
the prone position.Care
mustbe
taken to avoidpushing
the controlbar
forward
orback
causing
the glider to stall ordive.
This is
especially
important
considering
the closeproximity
to the groundduring
launch
andlanding.
Pilots
sometimeslook
toward theirfeet
whengetting
into
theharness
afterlaunch.
This in itself
is
not a good practice.But,
the
situationis
sometimesworsened
by
the
fact
that
the controlbar
is
in
the pilot'sline
of sight.Less
experienced pilots
have
atendency
to
inadvertently
move the controlbar
toget a clear view of their
feet.
Because
full
attentionis
focused
on thefeet,
the pilot no
longer has
a visualframe
of reference withthe
ground.So
eventhough the movementofthe control
bar
may
be
slight,the
results canbe
27
The
problem of studentsleaping
into the
airprematurely
on theirfirst
flights
caneasily
be
corrected withfull
motionflight
simulation.Even
thoughthe
student pilotmay
feel
the
controlbar
rising up
the
Gooney
Bird Trainer
will not support
the
student's weight untilthe
counterweightis
in
place.The
simulator responds
in
much the sameway
as an actualhang
gliderwould.Jumping
into
the air too soonis
followed
by
an abruptdescent
to the ground.The
difference is
that the
simulator pilotis
notmoving
forward
at10-15
milesan
hour
andtherefore
cannotbe injured.
Ease
ofOperation
Flight
simulation canbe divided
into
threebasic
stages: thelaunch
stage,the
flight
stage,
andthe
landing
stage.Each
of these stages requires adifferent
set of responsesfrom the
student and theinstructor.
Flight
simulationfor
the student.A
hang
gliding
instructor
needstoconcentrate on the student.
The
flight
simulatormay
be
a person'sfirst
exposure to
the
sport ofhang
gliding.If
the simulator appears complex,cumbersome,
or at all unpredictable,it
may
give an unfavorableimpression
ofthe
sport as a whole.For the student,
flying
theGooney
Bird Trainer is
generally
easier thanflying
a realhang
glider.While
the controlbar
is
resting
on the ground thestudent pilot
is
hooked into
the simulatorby hooking
theflight
harness
to thehang
strap
atthe
top
ofthe
controlbar.
The
student thenlifts
the controlbar
29
shoulders than an actual
hang
glider,
the student stillfeels
the50
to60
pounds of weight that can
be
expected whenlifting
a glider.While
running
in
place
during
a simulatedlaunch
the controlbar
getssteadily
lighter (as
thecounterweight moves
back)
untilit
"flys"up
offthe student's shoulders.After
running
afew
secondsmore,
theharness lifts
the studentinto
the air as well.Once
in
the airthe
student canlean
forward into
the
prone position andpractice gentle
turns,
pitchcontrol,
and straight andlevel
flight
(fig. 7).
While
coming
closer tothe
ground toward the end ofthe simulatedflight,
the student must
first
pushup
into the
upright position.The
landing
stagerequires
the
student togradually
push the controlbar
forward
to maintainaltitude and
"reduce
flying
speed".Just
priortotouching
down,
the pilot mustpush the
bar
forward
to afull
stall position to minimize ground speed(fig. 8).
Flight
simulationfrom
theinstructor's
point of view.The
simulator'scounterweight
is
attachedsecurely
to a motorized carriage.Using
a remotecontrol switch, the
instructor
can position the carriage anywherealong
thefull
length
ofthelever
arm.Prior
to thelaunch run,
the counterweightis
positioned
just
ahead ofthePRY
joint
to simulate the50
to60
pounds ofweight of a
hang
glider.During
the launch
run the counterweightis
movedback
gradually
tosimulate the
increasing
lift
as ahang
glider accelerates toflying
speed.Once
the student
is
airborne, the counterweightis
moved to a position thatperfectly
balances
the weight ofthe student with thelever
armin
ahorizontal
position.
The
counterweightis
left in
this position until thebeginning
ofthe32
Up
to this pointin
theflight
simulation, the controlbar has been
abletorotate around
its
own pitch axis atthe
end of thelever
arm.This
feature
allows the control
bar to
hang
in
a more natural positionduring
thelaunch
sequence.
A hydraulic damper
serves to restrain the motion of the controlbar.
Damping
provides the studentwith some pitch controlby
transmitting
theforce
of the control movements to thelever
arm.At
the end of thelaunch
stage,
however,
the controlbar
needs tobe
rigidly
fixed
to thelever
arm togive the student more positive pitch control
during
theflight
stage ofthesimulation.
This
stabilizing
effectis
accomplishedby
using
the controlbar lock
to connect the control
bar
struts to thelever
arm(fig
3).
During
theflight
stage ofsimulation,in
addition to verbaldirections,
theinstructor
can use theinstructor
link
to simulate crosswindsfor
which thestudent must compensate.
Just
priorto thelanding
stage of simulation the controlbar lock
mustbe
released
(fig. 9).
The instructor
thenbegins
moving
the counterweightforward
tolower
the student.Once
the student pushes the controlbar
into
the
full
stall position, the counterweightis
quickly
positionedjust forward
ofthePRY joint.
The
student settles to the ground, andis
once againsupporting
theweight of a
50-60
pound "glider".Portability
andAssembly
Portability.
The
simulatordoesn't have
tobe
very
realistic to pique the34
to
the
public.The
entire simulator canbe transported in the back
of afull
sizepick-up
truck and assembled at thetraining
ordemonstration
site.Assembly.
Four
people can assemble the the simulatorin
about30
minutes.
Two
people are needed to assemble the threelegs
ofthe simulator.The
twofront
legs
are slid onto short poststhat
arepermanently
attached tothe rear
leg;
the
support cables are then pinnedin
place(fig. 10).
A large
foot
padfits
onto a pin at the end of eachleg
to prevent thelegs from
sinking
into
soft ground ordamaging
woodfloors.
The
positioning
ofthelever
armis
the mostdifficult
part ofthe assembly.Two
people onladders
are needed, one on either side ofthe rearleg
toguide
the
twohalves
of thePRY joint
together.Two
people are also neededon the ground to
help
lift
thelever
arminto
place.Once
thelever
armis
secured, the pitch
damper is bolted in
place.A
total of31 2
pounds ofweight mustbe loaded
onto the counterweighttransport carriage.
To
makeloading
the weight more convenient thesimulator
is
designed
so the carriage canbe
moved to thefront
end of thelever
armallowing
the weights tobe loaded from
the ground ratherthan aladder (fig. 1 1).
There
are24 lead
weights that weigh13
pounds each.Each
weight
has
a slot that allowsit
to restsecurely
on theweight carriage withoutthe use oftools
for
attachment.The
controlbar
assembly
canbe
transportedfully
assembled.Two bolts
fasten
theassembly
to thefront
of thelever
arm. Anotherbolt fastens
the37
The
power cord runsfrom
thedrive
motor on the weightcarriage, down
the
inside
of one ofthefront legs
to a cable remote switch, and then to atwelve
volt powersupply
(fig.
3).
The
powersupply may
be
a carbattery
alone,
for
simplicity
during
short termuse;
a carbattery
withbattery
charger,
for indoor
instruction
ordemonstrations;
or attachedto
a carbattery
in
anautomobile, for
use at a remotetraining
site.Non-threatening
Attractive Appearance
The
name-Every
effort was made todevelop
adesign
that would reducethe
anxiety
ofstudents,
thisincludes
the
name:the
Gooney
Bird Trainer.
"Gooney
Bird"is
a nicknamefor
thealbatross,
asoaring
bird
thatis
known for
it's
gracefulflight
andclumsy
landings.
This is
a tongue-in-cheek reference tothe sport of
hang
gliding.Hang
gliders are also quiteeasy
to operatein
theair and often
exceptionally
awkward on the ground, evenfor
experiencedpilots.
The
name also suggests thatthis
simulator canhelp
studentsbecome
better
"gooney
birds".
Appearance.
The
anxiety
level
ofbeginning
students canbe
quitehigh,
but the
imposing
size or mechanical appearance of a simulator shouldn'tcontribute to this stress.
The
Gooney
Bird Trainer has
a playful, almosttoy-like,
appearance tostimulate
interest in
the simulatoritself,
as well as reduce theanxiety
offirst
time students.
Because
ofthe
sports-oriented nature ofthe product,it
wasgiven a
spontaneous-looking
spattered paintfinish,
similarto those
thathave
38
The
painted surface makes a transitionfrom
a chaotic multicoloredspattered
finish
on thelower
portion ofthesimulator, to
a simple purplebackground
with yellowflecks
at the top.This
transition
from
complex tosimple
is
a visual metaphorfor the
student's transitionfrom
earthbound toairborne.
There
are certain elements ofthe
mechanicaldesign
that areimportant
tothe
stability
ofthe simulator:the
threefoot
pads, the central cable connection,and the counterweight carriage.
These
elements were given a simulatedgranite
finish
to emphasize their role as components of strength and stability.Each
ofthe
stainless steel support cableshas
afluorescent
pinkcovering
to symbolize the
force
orenergy
transmitted through them.A
ratherlarge
granite textured sphere covers the central cable connection.
The
combination of all of these elements give the simulator the
look
of an oversized
Tinker
Toysculpture; a
look
that serves to put the students at easewithout
diminishing
theirconfidence.Safe
toUse
Safety
is
theprimary
reasonfor
using
ahang
gliderflight
simulator.If
thesimulator
itself
presents a significant risk to the student, theinstructor,
orthespectators, there
is
really
nobenefit in
using
it.
As
discussed
earlier,it
is
generally
accepted that thehigher
thefidelity
of a simulator, the greater thetransfer.
The
problem that arises,is
that a simulator capable ofrealistically
39
The
Gooney
Bird Trainer
wasdesigned
sothat
a studentin the
proneposition cannot contact the ground while the control
bar is locked in
theflight
position
(fig. 4).
When
the controlbar is
unlocked and the studentis in
thestanding
position, the
studentis
ableto
touch the groundfeet first
(fig. 6).
But
ascent and
descent
atthis
pointis
controlled moreby
the instructor
moving
the counterweight than the student's control movements.
The
counterweightdrive
motorhas
avery
low
maximum speed,eliminating
the risk oflowering
the studenttoo abruptly.
During
a simulatedflight,
while most people arewatching
the persondoing
theflying,
thereis
a300
pound counterweight atthe otherend of thelever
arm thatis
moving
ratherquickly
at times.To
minimizethe risk topeople
standing
nearby, the rear portion ofthelever
armis
short enoughthat
it
can come no closer than 6"6" to the ground while thelever
armis in
the maximum pitch
up
position(fig.
5).
Low
Cost
Manufacturing
The
target marketfor
theGooney
Bird Trainer is
hang
gliding
schools.The
very
small and specialized potential marketfor
this productdictated
theneed
for low
cost andlow
volumemanufacturing
processes.Where
everpossible, off-the-shelf materials and components were used to
keep
manufacturing
costsdown.
The
leg
tubes andlever
arm are made of 3.5"steel pipe with standard end caps.
An
actualhang
glider controlbar
is
usedin
the controlbar assembly,
and the struts are pre-anodized aluminumtubing
40
used to
build
the controlbar
assembly.The
foot
pads areactually
farm
equipment
harrow disks
thathave been
modified slightly.The
use of off-the-shelf components minimizes the needfor
machining
during
fabrication.
Whenever
possible,welding
is
usedin
manufacturing
tofurther
reduce the needfor
machining
and expedite themanufacturing
process.
The
only
componentsthat
requirefasteners
for
manufacturing
arethose that must
be disassembled for
transporting
or repair ofthe simulator.Steel
components that were susceptible torusting
are primed and painted.Manufacturing
costs willbe in
the$
1
000
to$
1
500
range.The
simulatorCHAPTER
5
THE COMPUTER AS A TOOL FOR INDUSTRIAL DESIGN
The designer's
ideas
aredeveloped
and communicated to otherslargely
through renderings and mechanical
drawings.
As
the power andsophistication of computer
hardware
and softwareincreases,
and as the costdrops,
computers arebeing
usedincreasingly
todevelop
and communicatedesign
concepts.One
ofmy
objectivesin
this thesis was to explore the use ofthe computer as a
design
tool.CAD.
A Macintosh
computerwas usedin
thedesign,
development,
andpresentation of the
Gooney
Bird Trainer.
The initial design began
with3D
CAD drawings
using
Intergraph's MicroStation.
Working
in
3D
quickly
resolved
many
questions of clearances and range of motion. Dimensionedpart
drawings
could thenbe developed for
building
the prototype simulator.Rendering.
Before
going
to prototype,however,
several computerrenderings were
developed
todetermine
the most appropriate appearanceofthe simulator.
The
scenedepicted in figure 12
neverreally
existed.The
picture was created
from
a combination of traditional photography,ray
tracing
software, andimage
editing
software.Because
it
was not possible to transfer thedrawing
ofthe simulatorfrom
MicroStation to another
3D
drawing
package,it
wasnecessary
to redrawthesimulator
in StrataVISION3d.
StrataVISION3d
is
a three dimensionaldrawing
and
ray tracing
software package.43
Objects
in
StrataVISION3d
arefirst
drawn
asthree dimensional
wireframe
structures which can then
be
assigned various surface attributes such ascolor,
texture,
pattern,
reflectivity
anddegree
of transparency.Components
of the simulator with solid colors were assigned the appropriate color and
given a gloss
finish.
Aluminum
components were given a mirrorfinish.
The
spattered paintfinishes
were created as twodimensional
surfacesin
Adobe's
Photoshop
(image
editing software) using
the gradation and airbrushtools.
The
surfaces were thenbrought into StrataVISION3d
and"wrapped"
around the appropriate components
in
a process calledimage
mapping.Even
though the surface attributeshad been
chosen, the simulator stillappeared as a wireframe
drawing.
The
nextstep
involved
a process calledray
tracing
in
which the computer calculates the path oflight
rays betweenthe
light
source, the object, and the viewer.Ray
traced objectslook
realisticpartly
because
they
cast shadows and areproperly
shaded.But
theprimary
reason these objects are so
convincing
is
thatthey
reflect their surroundings.For this
reason,it
wasnecessary
to
surround theflight
simulatorthreedimensionally
withimages
scannedfrom
photographs oftrees,
grass, and sky,before
ray
tracing.This
gave the gloss surfacessomething
to reflect.Once
theray
tracing
was completed, the simulator was "cut"from
thesurrounding
images.
It
was then"pasted"
into
an appropriatebackground
scene as a two dimensional
image
by
using
Photoshop.Care
was takenbefore
beginning
the
ray
tracing