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1/2KD

Boeing Flight Competition 2008

TEAM MEMBERS

Haftom Dessalegn

Kiki Mentan

Davi Ag!eman

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Ta"le of #ontents

$nt%o tion '''''''''''''''''''''''''''''()*

Const%tion '''''''''''''''''''''''+,)-

Detail #al#&lation'''''''''''''''*)8

Bi"liog%aph! ''''''''''''''''.)0

Ho/ to a##ess the M1 /iki'''''''''++,,)-,

The ½ KD glider

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Abstract

This report reflects our team’s effort in building and testing a glider using therequirements that were given for the Boeing Flight ompetition! The ob"ective of this pro"ectwas to design and build a glider that would fl# the farthest of all other gliders!

The design process consisted of determining the glider dimensions and some anal#sis onhow to ma$imi%e range! The glider had to fit in a & inches b# &' inches area of balsa wood with athic(ness of between 1/) to 1/* of an inch! +ur group did some trade studies of gliders andcalculations to determine what design would wor( best to meet our ob"ective!

,ll parts of the glider were made using 1/)-&-&' inches of balsa wood! .e used a gluegun to assemble the parts together and there was a pa#load which the glider had to carr#consisting of 2 0! ! quarters! The wing was sanded to ma(e it more aerod#namic and gave alittle bit of camber to it! arameters such as center of gravit# and tail position could be ad"ustedusing glider design boo(s! The abilit# to ma(e ad"ustments proved essential in allowingsuccessful flight!

.e found the initial velocit# of the glider that was generated from the rubber band! ,fterfinding the spring constant of the rubber we were able to get the initial velocit# of the glider! Toobtain the final velocit# used in our calculations we performed ten flight tests which were werecorded b# the distance traveled and the time it too(! +f the ten measurements we too( thema$imum distance and the time which we used and we were able to find the final velocit# of theglider! 0sing the initial and final velocit# we were able to calculate the average velocit# theglider traveled!

B# using the average velocit# in drag equations our team was able to predict thema$imum distance of the glider! The ma$imum distance we calculated for our glidercorresponded with our actual longest flight providing the validit# of our calculations! Duringthis pro"ect our team was able to successfull# build a glider and predict its action of flight!

Introduction

+ur goal for this pro"ect was to design an aerod#namicall# efficient glider that would fl#

the farthest! +ur team decided to perform calculations of the lift drag and ma$imum range!0pon doing so it tested our (nowledge of the effects of aerod#namic forces on fl#ing ob"ects!.e used some information from trade studies and personal (nowledge of aircraft flight to createthe glider!

The parameter we were limited to wor(ing with the glider had to fit in a &$&' inches areaand carr# a pa#load of 2 0! quarters! .ith this limitation we had to achieve the farthest range

possible! Knowing the glider’s ma$imum dimensions the method of launching the glider and the

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environment it would fl# in our team set out to design three gliders and then pic( the one of thethree with the most range!

Though two members of the team are in the ,erospace 3ngineering field the# didn’thave an# e$perience building a glider #et personal (nowledge was a big contributing factor tothe glider design! 4nitiall# we divided the pro"ect into three parts5 6aftom was in charge ofdesign Ki(i was in charge of manufacturing and David was in charge of documentation! ,ll ofus were to do the testing and lunching together!

+ur team first used information on glider designs and calculations to determine whatdesign will meet our ob"ective the best! +nce the design was finali%ed and built test flightswhere performed to determine which one of the three met our ob"ective!

Design:

.hen we start wor(ing on this pro"ect each individual team member did a trade stud#!+ne of the main things that ever# member of the group discovered was in order for us to meetour ob"ective we should ma(e a glider that has the highest aspect ratio possible so as to have thema$imum possible lift over drag ratio and that will lead us to get ma$imum range! The secondthing that our group agreed on was to design and build three gliders with different aspect ratio aswell as different fuselage wing and tail configuration! 7fig 8!!9 fig8!!9 fig8!!9:!

.e decided earlier on to have a highest aspect ratio 8,;9 with a wing span of 2< inches!The debatable parameter of the wing was the chord! The chord would have to be wide enough toma$imi%e surface area to achieve the greatest lift but short enough to reduce induced drag! .e(new that a taper wing can decrease the amount of induced drag so we decided that a goodcompromise between the two would be a chord length of 2 inches at the fuselage and 1!=> incheson the tip of the chord! This will give our glider an aspect ratio of 1

6ere are the three gliders we built5

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Fig 8!!9 with a tradition design and aspect ratio of

Fig8!!9 with a Double vertical stabili%er and aspect ratio of 12

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Fig 8!!9 with T?tail and aspect ratio of 1

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Fig8!!9

b# using this ,D file we laser cut the parts of the glider

Fig8!!9 now using this parts we can start sanding the wing the fuselage and the tail to ma(e theglider more aerod#namic!

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Fig 8!!!9 here #ou see part of the glider sanded and read# to assemble!

Fig8!!9 this is the assembl# portion where we used a hot glue gun to put our glider together!

Fig8!!9 we put the two quarters in the nose of the glider inside the fuselage to give a betteraerod#namic efficienc# to the glider!

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Fig8!!9 finding the center of gravit# 8cg9 of the glider!

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Fig8!!9 b# attaching the wing to the fuselage using a rubber band we chec(ed to see if the centerof gravit# #ou selected previousl# is the right place! 4t helps a hassle!

Fig8!9 after assembl# a fishing line was used to hang the glider from a ceiling in order to balancethe center of gravit#!

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Fig8!!9 this is the finished product of the glider using solidworks software!

Detail calculations:

Data ta(en from table 1 at the ma$imum distance the glider flewC

ma$E='!>ft

tma$E*!& sec

where aE maE?D

2ma$ 2

1at t V X += ∞

olve for ∞

at t

X V

21ma$ −=∞

Giving data5

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&&11grams9 we assumed IE.

s ft

slugs

!

1!<112*!<

=== ∞S q L

C L

Friction drag

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( )( )( )( )( )

( )

lbS V

Lq D L f

'

H

1!>

1

1>!*2' −

−

∞×=×==

S q

DC

L f L

f

4nduced drag coefficient

( )( )( )

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Conclusion

ome of the assumptions we made as predicted values were not the same as the ma$range of the actual value but were close8='!>ft9! This was the best distance that we of our tentrials! .e are glad that we got that far but we are sure our glider can do better since the actualdistance we measured is less than what we are supposed to get!

.e needed to find the spring constant 8(9 of our rubber band in order to find the initialvelocit# of our glider! ince the spring constant is different with different t#pes of rubber bandswe decided to find the spring constant of two different t#pes of rubber bands and we called themrubber band 1 and 2!

Fig !!!5 Finding the length change 8>!2> in9off of ;ubber band 1 after applied a weight 8

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Fig !!!5 Finding the length change82!> in9 off of ;ubber band 2 after applied a weight 8

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.here m

is the weight of the glider 8

ishow long the rubber band stretched when weight is applied to find the spring constant!

∆

= x

ma K

ow solve for K1 and K2

.herein x 2>!>1 =∆

andin x >!22 =∆

( )( )

ft

lb K

=12

2>!>

2!&2'>!<1

( )( )

ft

lb K

=12

>!2

2!&2'>!<2

)*!*=1 = K >!12 =

will be

m x K

V ii2

111 = m

x K V ii

222

2 =

( )( )

112*!<

12/1H)*!*= 21 =iV

( )( )

112*!<

12/>!1>>!1

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olving for the final velocit# of the glider5

Dma −= he%e

mis the weight of the glider 8

but it is going to be constant this time since the lift from the wing on theglider comes into pla#!

DSC q D ∞=

.here

2

21

f V q ∞∞ = ρ

ARC

C L D 1*!&

2

= and

S q L

C L∞

=

&&

2

2

1

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