Executive Summary: (Parikh) - Florida Institute of Technology

pressdeadmancrossingAI and Robotics

Nov 14, 2013 (3 years and 8 months ago)

122 views

MUAV2
1


Visit us at
www.fit.edu/projects/muav2

Executive Summary:
(Parikh)


Th
e purpose of this
document
is to put forward and report on the status of our
bid
to

design and manufacture
a

Miniature Unmanned Aerial Vehicle (
MUAV
) in order to
produce a
relatively
cheap, feasible and revolutionary aircraft

with versatile
control
capabilities. The
MUAV

2002
-
03 Team has already
claimed to have achieved powered
flight at the cost of its control sub
-
systems
; the
MUAV

2003
-
04 Team will
therefore
concentrate on
designing a craft from scratch with the added focus
being given to
improving the
control & stability of th
e

vehicle. The
MUAV

designs pose enormous
challenges pertaining to almost every engineering field. It tests the aptitude of an
aerospace engineer in designing a successful flying machine equipped with d
ucted fans.
Flow of air over these ducted fans

occurs

at very low Reynolds number
s (1000
-
10,000
refer Aerodynamic Mathematical Model). S
tructural instability
, lift
-
drag compensations
and complicated maneuverability make this project a perfect
challenge

for

an
y

aerospace
engineer. Most of all it provides an all round experience working with the mechanical,
electrical & computer engineering departments. Most of the material needed for
manufacturing the
MUAV

structure is easily available and very cheap. The pr
opulsion
system, power source, control and stability present some of the major obstacles.
In fact,
the successful design and flight of an MUAV is very heavily weighed towards the
technical and practical knowledge of the Electrical and Computer engineering
students.
These facts make this project extremely feasible for the students to accomplish within the
allotted time frame and stands out as a prime choice for a Senior Design project.

As
of
December

1, 2003
, w
e have achieved the ‘design freeze’ stage of our

project by finishing
up with the detailed design of our craft. In the following document, one will find the
detailed mechanisms involved in the designs and making of this MUAV.


MUAV2
2


Visit us at
www.fit.edu/projects/muav2

Table of Figures
:
(
Coutinho
)


Figure
number

Figure Name



1

H
and
-
drawn MUAV by J. Leeber

2

Hand
-
drawn MUAV by J. Leeber

3

Hand
-
drawn MUAV by J. Leeber

4

Pro/E model
-

MUAV by A. Burger

5

Hand
-
drawn MUAV by B. Parikh

6

Crown
-
Shape MUAV Assembly by B. Parikh (Designed with SolidWorks
)

7

‘Xis
J
=
MUAV’ Assembly by B
⸠.a物歨
ae獩sne搠睩瑨⁓潬odt潲歳o
=
U
=
‘Xis
J
=
MUAV’ Assembly
⡓Ec瑩潮o氠噩敷⤠
by=B⸠.a物歨
䑥獩gne搠睩瑨d
p潬o摗潲歳o
=
V
=
‘PFD
J
=
MUAV’ Hand
J
pke瑣栠ty⁊⸠ieeber
=

=
‘PFD
J
=
MUAV’ Hand
J
pke瑣栠tp楤攠i楥i⤠Fy⁊⸠iee扥r
=

=
‘PFD
J
=
MUAV’ Hand
J
pke瑣栠t
呯q
=
噩s眩⁢y⁊⸠
iee扥r
=

=
‘PFD
J
=
MUAV’ SolidWorks Assembly by B. Parikh
=

=
‘PFD
J
=
MUAV’ SolidWorks Design by B. Parikh
=

=
‘PFD
J
=
MUAV’ SolidWorks Design by B. Parikh
=

=
‘PFD
J
=
MUAV’ SolidWorks Design by B. Parikh
=

=
‘PFD
J
=
MUAV’ SolidWorks Design by B. Parikh
=

=
䝲潳猠oe
楧桴⁶献⁒ey湯n摳⁎畭扥r
=

=
䑵a瑥搠䙡渠剥灲e獥湴慴n潮
=

=
WEBRA
SPEED .91
-
P5 AAR HELI ENGINE

20

WEBRA
SPEED .75 P5 AAR HELI

21

SAITO
100 FA
-
AAC W/MUFFLER: QQ

22

O.S.

.32 SX
-
H Heli Engine

23

Different gear types

24

‘MUAV’ SolidWorks Design by B. Parik
h
=

=
‘MUAV’ SolidWorks Design by B. Parikh
=

=

MUAV’ Central Fan Assembly by Parikh
=

=

MUAV’ Central Fan Assembly Sectional View by Parikh
=

=

MUAV’ Central Fan Assembly
䕸灬潤敤
=
噩s眠wy=ma物歨
=

=

MUAV’ Central Fan Assembly
ma牴r
=
by⁐a物歨
=

=

䵕js
’ Central Fan Assembly Microcontroller by Parikh
=

=
C潮瑲潬⁶潬畭攠u牯畮r⁣e湴牡氠晡渠a獳敭扬y
=

=
p桡晴⁡湤ngea爠r獳敭扬y
=

=
f湤楶n摵d氠l潤o汳映瑨攠c潬oa爬畴r爠獨r晴Ⱐ楮湥爠r桡晴Ⱘ睩瑨潡摳⁡湤n
c潮獴牡楮i猩⁡湤ngear
=

=
䝥a爠瑯潴栠慬潮r=⡷楴栠汯慤h
=
a湤⁣潮獴ra楮i猩
=

=
噯渠䵩獥猠s物rge⁰汯=映c潬oar
=

=
噯渠䵩獥猠s潮癥r来湣e=灬潴⁦潲⁣潬oar
=

=
䑥景f浡瑩潮⁡湩浡瑩潮映f潬oar
=

=
䑥景f浡瑩潮⁣潮mergence⁰汯=映=潬oar
=

=
噯渠䵩獥猠s物rge⁰汯=映潵瑥o⁳桡晴
=

=
噯渠䵩獥猠s潮癥r来湣e=灬潴⁦潲畴敲
=
獨s晴
=
MUAV2
3


Visit us at
www.fit.edu/projects/muav2

41

Displacement animation for outer shaft

42

Displacement convergence plot for outer shaft

43

Von Mises fringe plot for inner shaft

44

Von Mises convergence plot for inner shaft

45

Top view of displacement animation for inner shaft

46

Side vie
w of displacement animation for inner shaft

47

Displacement convergence plot for inner shaft

48

Strain energy convergence plot for inner shaft

49

Von Mises fringe plot for gear tooth

50

Von Mises convergence plot for gear tooth

51

Displacement animati
on for gear tooth.

52

Displacement animation convergence plot for gear tooth

53


MUAV’ Central Fan Assembly Vibrational Analysis by Parikh
=

=

MUAV’ Central Fan Assembly Gearing by Parikh
=

=
‘RFA
J
=
MUAV’ SolidWorks Design by B. Parikh
=

=
‘RFA transpare
湴n
J
=
MUAV’ SolidWorks Design by B. Parikh
=

=
‘RFA
J
MUAV’ Parts Breakdown by Parik
h
=

=
‘RFA
J
=
MUAV’ electronics design
=

=
‘RFA
J
=
MUAV’ Duct Design by Coutinho
=

=
‘RFA
J
=
MUAV’ Duct Design Calculations by Coutinho
=

=
‘RFA
J
=
MUAV’ Rudder Design by Coutinho
=

=
C潮瑲潬⁶潬畭攠u牯畮r⁲ea爠ra渠n獳敭扬y
=

=
ia湤楮g=䝥a爠卨牯畤⁓異灯牴
=

=
‘LGA
J
=
MUAV’ Part Design
=

=
ia湤楮g=䝥a爠rng楮攠卵灰潲i
=

=
c牥e
J
B潤y⁄楡gra洠潦
=
p異灯u瑳
=

=
c牥e
J
B潤y⁄楡gra洠潦
=
c潭灯湥湴o
=

=
‘SWA
J
=
MUAV’ SolidWorks Design by B. Parikh
=

=
‘SWA
J
=
MUAV’ SolidWorks Design by B. Parikh
=

=
‘SWA
J
=
MUAV’
ma牴r
=
䑥獩s渠ny⁂⸠.a物歨
=

=
m楣瑵牥映=x灥物浥湴慬⁳e琠異
=

=
m汯l映=潥晦楣楥湴映汩晴f癥牳畳⁦ree獴牥a洠癥汯m楴y
=

=
m汯l映摲ag=c潥f晩f楥湴⁶e牳畳⁦ree獴牥a洠癥汯m楴y
=

=
m牯r
J
䡯畳楮e⁁
獳e浢myI⁣牥ate搠楮⁓潬o摗潲歳
=

=
呯瀠q楥i⁐牯瀠r潵獩ng
=

=
Ca湴n汥癥牥搠Bea洠䑩agra洠畳敤⁦潲⁨a湤
J
ca汣畬l瑩潮o
=

=
Cantilevered Beam


Truss Designed in Pro/E

78

Cantilevered Beam


Loads & Constraints

79

Von
-
Mises Stresses

80

VM Convergence Plot

81

Shroud with a stub

82

Loads and Constraints

83

Sectional Stress Concentrations

84

VM Stresses on 3d Part

85

VM Stresses Convergence Plot

86

R
ounded joint

87

Double Strap Method

MUAV2
4


Visit us at
www.fit.edu/projects/muav2

88

CCA
-

MUAV parts design

89

CCA
-

MUAV design

90

CCA
-

MUAV Electronic
s design

91

MUAV Top View

92

MUAV Side View

93

MUAV Front View

94

MUAV Rear View

95

MUAV Full Isometric View

96

Nominal budget

97

Minimal budget



MUAV2
5


Visit us at
www.fit.edu/projects/muav2

List of Symbols
:
(
Team
)

(This consists of the few unexplained symbols in the CDR body)



Serial
Num
ber

Symbol

Significance of Symbol




1

PFD

Previous Frozen Design

2

CFA

Central Fan Assembly

3

RFA

Rear Fan Assembly

4

LGA

Landing Gear Assembly

5

SWA

Shroud and Wing Assembly

6

CCA

Control and Communication Assembly

7



Norma
l Stress

8



Tangential Stress

9

axial


Axial Deflection

10

W

Weight

11

R

Reaction from Ground

12

C
D

drag coefficient

13

C
L

lift coefficient

14

D

drag

15

L

lift

16

p

pressure

17

Re

Reyn
olds No.

18

T

temperature

19

S

planview area, ambient temperature correction

20


=
晲ee獴sea洠捯湤楴m潮o
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
MUAV2
6


Visit us at
www.fit.edu/projects/muav2

Problem Statement & Objectives
:
(Coutinho)



Our main goal through
MUAV

II is to create a craft that will
be semi
-
autonomous
and maneuverable while performing
the

tasks it has been programmed to do. It should be
able to stabilize itself under certain conditions and must be able to sustain and suspend
itself without any external power connection for a minimum o
f
10

minutes. The size of
the craft will vary roughly between
10

in to 1
5

in. This provides us with more room for
added storage of electric components, integration of circuitry and for the housing of the
main propulsion unit. Our objectives can be better d
istributed between the following
topics.


FLIGHT



While our project may have goals that we have set for it, we recognize the
importance of not overstepping ourselves. Flight is our main aim currently. The craft
should be able to attain and hover in mid
-
ai
r at an altitude of roughly 2 meters without
any external help.

The craft will be free from any outside attachments such as tethers in
order to better serve understand how the stabilizing systems will have to be programmed
to adjust for uneven weight distr
ibutions.



CONTROL & STABILITY


While hovering, the craft should also be able to
maintain its sense of equilibrium without toppling over and should any unbalanced forces
occur, it should be able to promptly stabilize itself without any input commands fro
m the
main control center.


We hope to be able to integrate a functional thrust system that will help with the
movement of the system. We are currently still looking into what would be the best
systems to incorporate that would help most with the overall m
o
tion

of the craft.
The
presence of a counter
-
rotating fan system and a tail fan to improve balance and stability is
currently being studied as a possible integration within the craft system.


Other possible devices that may help with the overall control o
f the craft would be
the use of ducted fans which will increase the airflow through and hence the thrust
generated, an effective gear and cam system to control all the possible electronic
hardware such as motors and propulsion units, remote control/wireles
s systems to
effectively control the craft, and a user friendly GUI to increase craft control.


INTEGRATION OF ELECTRONICS


Based of how well the overall functionality
of the craft as far as movement is concerned, we will incorporate certain electrical
com
ponents into its structure. Some of the main ones are:
-


a)

Powering Devices (Batteries etc)



Since the craft will have to rely
extensively on its own power cells, the lifespan of the average power cell that
we use is a very important factor in deciding how
long our craft will be able to
maintain its ability to hover.

b)

Microsoft Flight Control Sidewinder Joystick


Dwayne has already
finished programming the GUI for the use of the Microsoft Sidewinder
Joystick. Current programming includes the use of a 2
-
butto
n system to
modulate the thrust increase and decrease and the use of the actual joystick
grip to control normal 2D motion. Note however, that for the purpose of
MUAV2
7


Visit us at
www.fit.edu/projects/muav2

MUAV2, the need for reverse motion has been neglected and hence will not
be programmed into the

GUI code.

c)

Camera


A camera will be mounted onto the front of the craft. The camera
currently being studied comes with its own electronic board for transmission
purposes. It will be able to transmit via UHF directly to a NTSC TV system.
This main factor c
oupled with the small size and weight of the camera make it
an ideal choice as of right now since its transmission capabilities will mean
less time being spent on designing the onboard camera electronics.

d)

GPS



The integration of a Global Positioning Syste
m is currently still in the
works owing the fact that MUAV2 will be a line of sight based operation.
Hence a GPS would not be very relevant as far as positioning itself goes.
However they can be utilized for many other things instead ranging from
altitude
to velocity. Therefore, a
Global Positioning System
might

help in the
effective control and guidance of the craft while
helping to
always maintain an
active readout of its position
and other data for the rest of the MUAV2 Team
.

e)

Transmitter/ Receivers


Cur
rently Chris is studying the possible use of a 4
channel transceiver for use on the MUAV2 craft.

f)


Microchips and controllers



These will be necessary in the programming
and control of the craft. The craft can be effectively programmed to be semi
-
autonomou
s depending on the particular situation it undergoes.


Power


The problem of a feasible and applicable central power source is a factor that
continues to provide problems. We studied four different alcohol engine designs for the
powering of the main propu
lsion system consisting of a set of counter
-
rotating fans.
(Refer Power Sources for more info on engines). From these we decided on the O.S
engine which seems to present the best overall practical usage statistics for our project
purposes. Should we fail i
n trying to power the craft with this engine, a reasonable and
feasible idea also seems to be the integration of a tether
-
like a.c power cord to provide all
power requirements so that we can rely completely on electric propulsion units.
Although, this woul
d be a worst
-
case scenario, we must not discount it completely.



Project Status:
(
Coutinho
)



As of December 01, 2003 we felt that we had sufficiently studied and
concentrated on the different pros and cons of all the various designs put forward enough
to

decide on a particular design. It is this design that will henceforth be called our frozen
design (FD) and that we will attempt to construct for the purpose of our Senior Design
project 2003
-
04.

We have analyzed the manufacturability of most of the parts
that we
have introduced into our design. We have also finished the mathematical analysis and
calculations of most of the major design components including the main fan assembly
(central fan assembly
-

CFA), the shroud aerodynamics (shroud and wing assembly

-

SWA), the gear ratios for the central fan system (CFA), the landing gear stress analysis
(landing gear assembly


LGA), and the rear propulsion assembly (rear fan assembly
-

RFA)
. We have already made the purchase of our pusher and tractor propellers an
d
have
also bought our
MUAV central fan assembly

engine
as of Friday, December 05, 2003.

MUAV2
8


Visit us at
www.fit.edu/projects/muav2


Finally, we have also decided on the control mechanisms and subsystems for our
craft
.

Recently, we have made the acquisition of a room in the Grissom Residence Hall
f
or MUAV’s Design Project Purposes.



Project Limitations:
(Parikh)



MUAV2 seems like a very feasible design project. Like most of the other senior
design projects, our project is constrained by several unpredictable factors. Capital is the
primary catalys
t for production, and thus it can affect our project’s progress. Team
planning hardly involves any expenditure; while the construction of and testing process
requires the bulk amount of capita. Ordering parts, raw materials, testing equipment,
construction
, and stationery are some of the major expenses. Our nominal budget has shot
up to almost $1800 which although substantial, seems minor in comparison to the tens of
thousands of dollars that some of the other Senior Design teams have been proposing. We
hav
e acquired $450 from the Florida Tech College of Engineering Dept. and are
expecting donations from some companies and firms. At present the expected donations
and sponsorships look positive; but incase of not being able to get these funds we also
have our

minimum budget at the cost of some major parts of the project. Thus Money
controls our project greatly. Experience & Knowledge play the most important role in
cultivating the project milestones. Being seniors/juniors we lack knowledge and
experience in ma
nufacturing, project planning, and professionalism. Our undergraduate
status restrains us from developing proficient scientific thinking. Thus Knowledge,
Experience and Techniques curve the progress of our project. In spite of this lack of
accurate enginee
ring skills, our ideas are extremely innovative & artistic. “This creativity
of ours may shape our future inventions”, this thought restores the team’s potential. The
shortage of construction & testing facilities offer another hurdle to the MUAV2 team.
Our

project involves relatively small parts and thus requires smaller workspace and thus
it does not concern us much.
For the purpose of building our craft we have been given a
room on the third floor in the Grissom Residence Hall.
The senior design project i
s to be
finished in the allotted time frame which practically is extremely short for the project
planning, designing, implementing & testing. This short period is not our major concern
if everything works out as planned.




Background
:
(Leeber)



With the
new millennium under way, it is inevitable that technological
breakthroughs will occur. One of these breakthroughs is the production of the micro
unmanned aerial vehicle (
MUAV
). These machines tend to be around six inches in
length, but in the future, th
ey may be the size of an insect. Applications of the
MUAV

are endless. Probably the most noted application is military reconnaissance. The
MUAV

could fly across
unknown

terrain and detect the location of
a possible

enemy or use
sensors to detect landmin
es. Besides military functions,
MUAV
s can also be used to
detect harmful chemicals in the air, or make use of infrared cameras to find victims in
burning buildings. Other functions may include surveillance for warehouses and private
MUAV2
9


Visit us at
www.fit.edu/projects/muav2

business buildings.
In addition, a
MUAV

could fly above cities to monitor traffic
patterns or civilian activity.


As good as this sounds, the production of
MUAV
s brings about a challenge with
stability and control. Scientists and engineers have been discovering that the
mat
hematical relationships that are used to design conventional airplanes do not apply to
much smaller aerial vehicles that will fly at very low speeds. From a structural
standpoint, these aerial vehicles are very small in size; thus, their control surfaces,

motors, and fans are smaller. As a result, those parts will be harder to make and easier to
break. As a final note, the size of the
MUAV
s may limit their use depending on
atmospheric conditions. High winds and precipitation
would

create a problem with
stability and control

and could render the craft immobile.



Background

continued:

(Coutinho)


While the acronym
MUAV

correctly stands for “Micro Uninhabited Aerial
Vehicle”

(Ref. 1)
, it has also come to be loosely acquainted with other similar derivations

including
Miniature Unmanned Aerial Vehicle
.

The idea of miniaturized flying devices actually originated with the Defense
Advanced Research Projects Agency (DARPA). Their initial applications were to involve
military usage where these vehicles would becom
e the eyes of various army personnel on
the ground especially in active combat situations.
MUAV
s were to help in reconnaissance
and surveillance and in the detection of chemical and biological weapons.


“In order to qualify as a
MUAV
, the US Defense Airbor
ne
Reconnaissance Office (a key organization in
MUAV

development) insists that
the aircraft must be less than six inches in length, height and wing
-
span. They
must carry a "miniaturized payload", a tiny version of reconnaissance cameras,
sensors or other m
ilitary equipment; they must be simple to operate and they must
carry a communications link for the transmission of information.” (
Ref. 1
)



While these initial aspects of the UAVs led to interest in their applications, it was
subsequent government focus o
n the advancement of UAV technology that actively
spurred on the concept of
MUAV
s as feasible, cost effective, and highly effective
devices. Other applications for
MUAV
s were envisioned besides military usage. These
new visions focused on
MUAV
s being used
to help combat terrorism, detect trapped
people in burning buildings (
Ref. 1
), mine
-
detection, the measuring of atmospheric
conditions, and traffic control and regulation.


A typical
MUAV

mission would consist of flying 1km to a
possible
point of
interest,

loiter in close proximity for
a
1/2 hour and then return. During flight the aircraft
is expected to encounter turbulent winds up to 25 mph, perform tight turns near buildings,
and climb repeatedly to 350 ft. altitude. The aircraft must be stable enough to

serve as a
live airborne video platform and must be easy enough to fly so that an individual with
minimal training can operate it. Currently, there are
almost no

UAV designs which meet
these criteria and many technical issues must be resolved before a suc
cessful
MUAV

can
be produced.

MUAV2
10


Visit us at
www.fit.edu/projects/muav2


MUAV

II is actually a continuation of the previous
MUAV

group
’s attempt at the
construction of a working MUAV
. While our aim is dynamically structured over much of
the previous year’s ideas,
MUAV

II aims to
focus on the

maneu
verability feature
of

the
craft th
ereby making it
easier to
control

in 3 dimensional flight. Added electrical
component
s

would include data
-
loggers, electromagnetic component systems for possible
mine detection and a global Positioning System that would he
lp in the navigation of the
craft.




Project Management:

(
Parikh
)


Plan and Schedule



MUAV2 is a very well organized engineering team with 17 devoted team
members. The team consists of nine Electrical & Computer Engineers, one Computer
science, 3 Mechani
cals, 6 Aerospace Engineers. The MAE team has enormous input into
the design of the aircraft. Microsoft Project is being used to monitor progress and to
organize the project. The Attached Gantt Chart briefs through details of every major task
achieved and
predicted during the Fall 03 and Spring 04 semesters respectively. MAE
team has always followed the work distribution pattern and thus has successfully
completed the design. Starting spring 2004, the team sets the goals on manufacture of the
prototype and
testing it. The following is a short list of team members and their major
contributions to the project design: (Note: This only includes engineering design part of
the project)


Table 1:

Team Task Workload

Team Member

Major Contribution towards Design

Bro
wn

Central Fan Assembly, Gearing
, MUAV Design

Parikh

Central Fan Assembly, Shroud, CAD

Coutinho

Rear Fan Assembly

Lungu

Rear Fan Assembly

Leeber

Landing Gear Assembly

Grelck

Landing Gear Assembly

Burger

Shroud Design


Please refer the Gantt chart, W
BS, & Organizational Charts in the Appendix for more
details.




Viable Options from brainstorming sessions

(Lungu
/Coutinho
)




Use 2 counter
-
rotating coaxial fans

(Most Feasible)


This is the most feasible option. Two counter
-
rotating propellers will be
mou
nted about the same axis with one on top of each other. These fans would be
MUAV2
11


Visit us at
www.fit.edu/projects/muav2

responsible for the overall upward thrust of the system and would hence be the
main propulsion block. They will both be powered by the same central engine and
the power transmissio
n. It was decided to use one engine instead of two because
of weight considerations and the fact that fuel consumption would increase
exponentially with the presence of a second engine. The weight that would come
into play here would be the weight of both
the extra engine and the amount of
extra fuel that would definitely have to be carried. A third fan will be connected
horizontally to the back of the MUAV to provide forward thrust. This fan will be
powered by an electric motor because it is physically imp
ossible to transmit the
work that the central engine block could produce to a rear fan since it would result
in too many power losses and increase fuel consumption exponentially.





Use 2 fans side
-
by
-
side for lift

(Highly Unlikely)


This was ou
r earlier propulsion design for MUAV2. We were going to
have two counter rotating fans to stabilize the craft’s turning moment by using
counteracting moments. However, this design was abandoned because the thrust
produced is proportional to the radius of t
he blades. Therefore, it was decided to
have two co
-
axial fans with a large radius to increase the thrust instead of have
two fans side
-
by
-
side which would have had a smaller radius and consequently
produced less thrust.




Use alcohol engine (Most Feasib
le)


The type of engine we were going to use was another major design
consideration. It was finally decided to use an alcohol engine because we could
increase the overall thrust of the craft since these engines generally have a higher
rpm and can better ov
erall efficiency than a normal electric cell. Since fuel is
being used up, the weight of the MUAV would also decrease with time. This
would be advantageous because eventually, we would need less thrust to stay in
steady level flight. Since we are aiming fo
r a flight time of approximately 15
minutes, this was the best.





Use of electric engine
instead of the alcohol engine
(Feasible)


This was our earlier option to power the motor that would be responsible
for the fan creating the upward thrust of the craf
t. However, the flight time would
have been limited to only a few minutes unlike the alcohol engine, since the
batteries would have their energy depleted in under 10 minutes. However, there
have been new developments in the technology that goes into the pr
oduction of
longer
-
lasting Lithium Polymer batteries for remote controlled vehicles. We are
currently instead researching the use of these rechargeable batteries for the rear
electric motor.




Tethered flight using power cord from alter
nating current main
to power
(Feasible)


In the unlikely event that we do not have enough money even to meet our
nominal budget, we would use this alternative power method. This would be very
cheap since we would just connect our craft to an alternating current power
source.

However, this is uninteresting because we wouldn’t be fully able to
MUAV2
12


Visit us at
www.fit.edu/projects/muav2

observe the stability characteristics of the UAV in free open area flight. Its other
advantage is that it would greatly decrease the weight of the vehicle since we
could do away with bo
th the need for fuel and batteries.




Use of pendulum type device to stabilize craft (Feasible)


Our biggest problem with MUAV2 will probably be static and moment
stability. Dr. Sepri suggested an innovative idea of overcoming this problem by
hanging a pend
ulum to the bottom of the vehicle. By so doing, the aircraft will be
inherently stable because the pendulum will always tend to bring it back to it’s
neutral position. The drag consideration of hanging a bluff body to the UAV can
be neglected because of
our low flight speed. Therefore, since this is a very
promising alternative to stabilize our craft we have set
-
up the engine and fuel
blocks such that they’re overall center of mass will act in much the same way as
the pendulum and help stabilize the craf
t.





Use of 2 step gyros to stabilize flight(
Unlikely
)


Another way of stabilizing the aircraft during flight would be by using 2
step gyros which would detect the motion of the craft in relation to a set
horizontal and vertical tilt axis. Gyros are gene
rally used for taking position
measurements. Based on its measurements, the gyro would influence its control
program to help stabilize the craft. This means that a chain control network would
have to be set up so that the craft could stabilize itself. Furt
hermore, added
mechanical components would have to be included in the overall design to ensure
the smooth operation of these gyros. This would increase overall weight thereby
decreasing the overall thrust to weight ratio for the craft. Also, the two parame
ters
would have to be set up for different conditions owing to the fact that the MUAV
is both an indoor and outdoor capable flying machine. Hence this idea is not
feasible.



Trade
-
Offs With Our Current Design

(Lungu)




Thrust of each engine can’t be varied
.


Even though both engines are connected to different shafts, both shafts are
connected to the same engine. Previously, we could have controlled yaw stability
by varying the thrust of one fan. This would have created a torque in one
direction and the
MUAV would have been able to turn right or left with respect to
the horizontal axis. However, this would have required having two different
engines (one connected to each fan). Since we are trying to minimize the weight
and the cost (the engine is our mos
t expensive component), we decided to have
just one engine and have both fans connected to the same engine by use of gears.
However, we will be able to move the aircraft in yaw by vectoring the thrust from
the third fan which will be mounted in the horizo
ntal axis and will be providing
forward thrust. At the moment, we are planning on using two rectangular plates
which will be mounted to the exit of the third fan. These plates will be used to
vector the thrust left or right thereby giving us control of t
he direction in which
MUAV2 will be heading.

MUAV2
13


Visit us at
www.fit.edu/projects/muav2




Power losses in gears reduce thrust.


As earlier mentioned, both fans will be connected to the same engine to
save on weight. However, since we want to have two counter rotating fans, they
will each be conne
cted to their own fans. The shaft from the engine has a gear;
this gear will be connected at 90° to a gear above and below it .i.e. the gear’s teeth
will be at 45° to each other.
The gears will have considerable loses of power due
to friction. We will a
lso have to make careful calculations of the rate of turn of
the gears because we do not want them shearing off from high torques.





Aerodynamic Interference of Fans


This is of minor consideration given that our fans are operating at a low
number of r
evolutions per second. The problem can be overcome by distancing
the fans so that they are not too close to one another.




Roll stability by varying thrust won’t be possible since fans are coaxial
.


In our previous design, we were going to have two fans mo
unted side
-
by
-
side. We would have controlled the rolling motion of the MUAV by varying the
thrust produced by one engine. This would have caused an unbalanced moment
on the vehicle and this would have been used to make the vehicle to roll in the
directio
n of reduced thrust. However, since the engines are coaxial, you cannot
use this control mechanism.

Note: Pictures of MUAV2 are included in later parts of the design report
.




Design:
(Leeber
/Coutinho
)



The group has create
d

several preliminary design
s. However, before finalizing
the design, there
we
re several considerations and limitations that need
ed

to be addressed.
In defining a final design, the group need
ed

to primarily consider stability, component
placement, and overall weight.


Stability i
s probably the single most important aspect of our project. If a
MUAV

is not stable during flight, it will not be able to perform any of its useful functions or
capabilities. To help keep our vehicle stabilized, the group has to make a few important
deci
sions.
T
he group has
already

decide
d to use a set of counter
-
rotating fans as its main
propulsion system. There are more pros for the use of this design aspect vs. its cons. The
previous consideration of a set of fans rotating about a parallel axis system

while feasible
did not seem like it would be able to generate the needed amount of thrust for lift
-
off.
One problem with the counter
-
rotating single
-
axis fan system is that the
fans
will
need to
be calibrated so that they are in equilibrium

as far as thei
r torques go. This is largely a
gearing problem although frictional and power losses within the gearing system must not
and cannot be neglected otherwise the
vehicle
may
spin out of control. The
number of
blades of the fan
and the fan blades themselves al
so need to be considered.
The group
needs to figure out what type of airfoil the blade should be and the number of blades for
each fan.
Currently, we are employing a 2 bladed fan system. The 2 blades for the fan
MUAV2
14


Visit us at
www.fit.edu/projects/muav2

would be best since they would require a les
s amount of actual manufacturing effort and
are cheaper as opposed to a greater number of blades.

The
main advantage of the
c
ounter
-
rotating fan system
is that it would prevent
spinning.
A the rear of the craft, a
smaller electric motor will be attached
in order to provide for forward motion of the craft
since adjust the pitch of the fan blades on the main propulsion block will create other
instabilities that need to be effectively handled. This would require too complex of a
feedback system for our curre
nt purpose and would also be tough on our ECE side since
they would have to create a code that can decide what action to perform in order to
stabilize the craft. Besides providing for forward motion, this rear fan can also be
effectively used with the aid
of a nozzle to help with left and right turning.
Besides the
fans, stability can be achieved by control surfaces. More specifically, the team
will add

wings or a tail in order to keep the vehicle under control when in flight.

The presence of a
tail struct
ure is currently being studied since it can provide an effective component
placement section for our electronic circuitry.


The c
omponent placement
section is therefore

also very important and should be
carefully addressed.
Since the components will be res
ponsible for anything and
everything that the craft will do, it is very important that we consider placing them in a
region where they are open to the least chance of physical failure from damage due to
hard landings, crashes etc. These c
omponents may incl
ude batteries, GPS, cameras, or
sensors. The location of a component may be crucial to the functions of a specific
MUAV
. For example, a camera should be placed in location that gives it a clear view of
the surroundings. If the camera can rotate, it need
s to have a 360


view. Since a
MUAV

is a flying vehicle, its center of gravity is very crucial. Improper placement of
components may result in control failure thus leading to stalls or flips.
Also, placing the
components in locations where they will hel
p us effectively constrain the center of
gravity of the entire craft close to the center of lift is very important as any offset of
components such that they affect the C.G. would coz instabilities and unwanted moments
on the craft. This is why placing is
very important. Furthermore,
the
se components will
have to be placed
appropriately s
uch that there
is no point where the stress is extreme.


T
he total weight is a consideration that must be taken seriously, especially for an
aerial vehicle. The
MUAV

must
be light enough to fly, or else it is inefficient. In order
to decrease the total weight, the group needs to determine a sufficient type of material,
how powerful the fans need to be, and also the number of components that will be used.
For the final des
ign, the group will use the lightest material that they can afford and the
number of components will be based upon what the group wants the
MUAV

to be
capable of. For example, the students may install sensors so that the
MUAV

is capable of
detecting landm
ines.

MUAV2
15


Visit us at
www.fit.edu/projects/muav2

Design Perspective

(Parikh/Leeber
/
Brown
)



Along with the advancement in technology, and the complexities surrounding
new machining tools, the Computer Aided Designing has become the engineer’s new best
friend. There are several CAD software availab
le in the market; we chose to use Pro/E,
Pro/M and SolidWorks 2003. SolidWorks is more user friendly than Pro/E and has
special features like Photoworks, Featureworks, Cosmos Xpress, etc. integrated into its
shell for added performance designing. The froze
n design has been developed on
SolidWorks 2003’s 3D modeling system. However, before we could start on the CAD
modeling, it was necessary that we go through several brainstorming sessions of different
designs. During our sessions, we listed the pros and co
ns of each model before deciding
on the best and most feasible option for our craft designs. This discussion is followed by
some preliminary designs (overviewed during brainstorming sessions), a few hand
sketches that enabled us to put our imagination on p
aper and in front of the crowd, and
completed CAD drawings of various odds and ends that when put together make up an
MUAV.




Preliminary Designs
:


Design 1
:



Single Lift Fan/ Electric
Motor



Tail Fan for counter
rotation (acts as a
moment arm) & turning
m
otion control(left &
right)



Fiberglass front panel
for integrated
electronics & batteries



Ski stand legs for
controlled & balanced
landing/takeoff


Figure

1
: Hand
-
drawn MUAV by J. Leeber













MUAV2
16


Visit us at
www.fit.edu/projects/muav2


Design 2
:




Single Lift Fan/ Electric Motor



Curved horiz
ontal tail stabilizers



Tilt
-
rotor system for exclusive
maneuverability



Rubber/ Nylon bottom ring for
reducing shock during landing



Front Fiberglass panel for
electronics

Figure

2
: Hand
-
drawn MUAV by J. Leeber



Design 3
:




The Four Fan system intended for
enormous thrust



Balanced body
-
rotation



Ski stand legs



Fiberglass molded shell with micro electronics




Figure

3
: Hand
-
drawn MUAV by J. Leeber


Design 4
:



Pro/E modeled one
-
piece
part (modeled by Burger)



Refined version of
Design 1



Complete carbon fiber
structure



Possible entity for a 3D
printer



Figure

4
: Pro/E model
-

MUAV by A. Burger




MUAV2
17


Visit us at
www.fit.edu/projects/muav2



Design 5
:



Figure

5
: Hand
-
drawn MUAV by B. Parikh






Cypher
-
like MUAV



3.5” Ducted fan



Friction
-
less (bearing) fan shroud connected to the outer body



Tilt
-
rotor me
chanism for 6 DOF motion



Tail Fan


Exclusively designed for forward motion



Expanded wing
-
span for better stability



See
-
Thru Fiberglass casing for camera & microcontroller installation



Rubber/ Nylon bottom for shock resistance



Back Flaps (Not feasible due
to low Reynolds Number)









MUAV2
18


Visit us at
www.fit.edu/projects/muav2




Design 6
:



Figure

6
: Crown
-
Shape MUAV Assembly by B. Parikh (Designed with SolidWorks)






Crown
-
Shape Assembly



Single Ducted Fan



2 gyroscopic rings for 2 axial motion



Crown faces for installation of electronics and batt
eries



Motor
-
Fan one
-
piece assembly



Gyroscopic rings can move 45 degrees in either direction












MUAV2
19


Visit us at
www.fit.edu/projects/muav2





Design 7
:





Axis symmetric disc
-
MUAV



3 gyroscopic rings for 3
axial motion



Single Ducted fan with
an integrated motor



Open Fan Shroud



Frictionless 3
rd

ring
creates counter
-
rotary
moments



Outer Nylon tank used
for storing compressed
air/ fuel/ batteries,
depending on the type
of propulsion



IMU installation
necessary

Figure

7
: ‘Xis
-

MUAV’ Assembly by B. Parikh (Designed with SolidWorks)











Figure

8
: ‘Xis
-

MUAV’ Assembly


[sectional view] by B. Parikh (Designed with SolidWorks)


Fan Blades

Motor

Ring 1

Ring 2

Ring 3

Friction Reducer Fluid

Nylon Tank

MUAV2
20


Visit us at
www.fit.edu/projects/muav2





Design 8

Hand Sketches

by J. Leeber






Figure

9
: ‘
P
FD

-

MUAV’ Hand
-
Sketch by J. Leeber





2 co
-
axial Fans (3 blades each)

geared in opposite direction for counter
-
rotation



Carbon Fiber outer shroud



Tail wings for stability and integration of possible IMU’s & Micro controllers



Engulfed tail fan for forward and side motion (good for moment balances)



2 lateral Ducts for suffici
ent airflow to the tail fan



Vector
-
Flaps for vectoring the flow of air through the tail fan exit



Battery motor for tail fan



Internal Combustion Gas/Alcohol Engine for thrust in vertical direction



Camera placement panel in the front most section








MUAV2
21


Visit us at
www.fit.edu/projects/muav2

P
FD
-
MUAV

(side view)




Figure

10
: ‘
P
FD
-

MUAV’ Hand
-
Sketch (Side View) by J. Leeber



P
FD

(Top View)



Figure

1
1
: ‘
P
FD
-

MUAV’ Hand
-
Sketch (Top View) by J. Leeber


MUAV2
22


Visit us at
www.fit.edu/projects/muav2


P
FD FAN
-
MOTOR
-
GEAR

(Assembly View 1)



Figure

1
2
: ‘
P
FD
-

MUAV’ SolidWorks Assembly by B. Parikh

Advanced Effects
:

PhotoWorks @ SolidWorks



The above shown picture displays the Motor attachment with the two co
-
axial
fans. There are 3 visible gears (possibly bevel gears). The above arrangement of

gears
enables the two fans to rotate in opposite directions.


The detailed Drawings of the MOTOR
-
FAN
-
GEAR assembly are as follows:


P
FD


MUAV

(Guiding Shafts & Gears)



Figure

1
3
: ‘
P
FD
-

MUAV’ SolidWorks Design by B. Parikh

MUAV2
23


Visit us at
www.fit.edu/projects/muav2

P
F
D


MUAV

(Fan Assembly)


Figure

1
4
: ‘
P
FD
-

MUAV’ SolidWorks Design by B. Parikh


P
FD


MUAV MOTOR
-
FAN
-
GEAR

(Assembly View 2)


Figure

1
5
: ‘
P
FD
-

MUAV’ SolidWorks Design by B. Parikh


MUAV2
24


Visit us at
www.fit.edu/projects/muav2




PFD


MUAV ‘MOTOR
-
FAN
-
GEAR’ Assembly Wire Frame View

Figure

16
: ‘PFD
J
=
MUAV’ SolidWorks Design by B. Parikh
=

MUAV2
25


Visit us at
www.fit.edu/projects/muav2

These preliminary designs have both positi
ve and negative influence on our currently
frozen design. Every design has its own drawback.




Technical Approach


Aerodynamic Mathematical Model:
(Burger)


When analyzing the flight characteristics of a very small vehicle, such as an
MUAV, nothing can be

done to accurately predict them aside from testing prototypes in a
trial and error system. The first and probably most important obstacle to overcome when
trying to build a successful vehicle is the fact that MUAVs are categorized in the low
Reynolds num
ber regime (1000’s to 10,000’s). The Reynolds number is a ratio of the
inertial forces and the viscous forces of and on an object. Since an MUAV has relatively
inertial forces behind it, the viscous forces in air tend to decrease the Reynolds number
by d
efault. Because of this, the governing equations that can be simplified for very large
Reynolds numbers, namely those in the millions, cannot be reliable. Therefore, as was
mentioned earlier, any predictions of the flight behavior of such a small aircraf
t must be
tested for experimentally.
As one can see from the accompanying illustration (Fig. 1
7
),
the MUAV Reynolds number is about 200,000, a very low number compared to the C
-
5
Galaxy which has a Reynolds
number near 100 million. The
designs most affe
cted by low
Reynolds number are those
aircraft relying on a fixed wing to
produce lift. Another
disadvantage of the fixed wing
design is the fact that, since
MUAVs are typically very
compact, they tend to have wings
with very low aspect ratios. A
trend s
een among fixed wings is
that as the aspect ratio is
increased, the capabilities of the
wing increase, and thus in effect
the wing becomes more efficient.
Low aspect ratio wings, therefore,

Figure 1
7
: Gross Weight vs. Reynolds Number (Ref. 2)

are not uti
lized that often in aircraft design and so there isn’t much published data about
them.





Even though all MUAVs fall in the low Reynolds number category, our particular
design will not necessarily be restricted by it. Our design will
incorporate ducted fans to
produce lift. Essentially, we want a craft that is capable of vertical take off and landing,
as well as horizontal flight. Since our proposed craft will not be using wings as the main
component of lift, a low Reynolds number an
d low aspect ratio is only a small hurdle to
MUAV2
26


Visit us at
www.fit.edu/projects/muav2

pass over. One way to estimate the amount of lift we will produce is to input our
variables directly into the general thrust equation, which is:



(1)



In the figure below (Fig. 2), the major components of
equation (1) can be
identified. The variables
m
e

and
V
e

are the mass flow rate and the velocity at the exit,
respectively and are represented by the lower half of the downward arrows. On the other
side, the variable
m
0

and
V
0

represent the mass flow rate

and velocity at the inlet,
respectively, and are represented by the upper half of the downward pointing arrows.
The variables
P
e
,
P
0

and
A
e

are the exit and inlet pressures, and exit area, respectively.


Several variables have to be taken into account wh
en calculating the theoretical
thrust that will be produced
by the individual fans.
Such variables are: power
output of the fan, velocity
of the aircraft, and the exit
area of the duct, among
others. The last variable
mentioned can be designed
to our own

specifications in
order to get optimal
performance out of the
fans. In the illustration to
the right (Fig
18
) one can
see how the principles of
ducted fan theory work. In
general, as the fan draws in


Figure
1
8
: Ducted Fan Representation (Ref. 3)

air
, the change in the velocity of the mass air flow produces along with the inlet and exit
pressures, as governed by the general thrust equation, puts Newton’s third law to work.
One design element that can increase the thrust from a particular fan is the a
rea of its exit.
As is dictated by subsonic flow theory, subsonic flow traveling through a converging duct
increases in speed. Therefore, as the speed of the exit fluid increases, the mass flow rate
increases; hence the thrust increases, given that the o
ther variables are the same.













Two main designs in particular are in the process of debate, namely the number
of fans to use. Using one central fan would require the use of counter
-
rotating blades in
order to compensate for the torque produced
by one blade. Using more than one fan at
various “stations” around the vehicle would require precise calculations of the distance
between the fans and the correct rotational speed settings to counter the torques and
produce even state of lift for the enti
re vehicle.


Ducted fan thrust vectoring is an option for this project. One simple example of
ducted fan thrust vectoring is the ducts in a car’s air
-
conditioning system. The driver or
passenger is able to direct the airflow to his or her desired directi
on. Thrust vectoring
works in a similar manner. As the fluid is projected through the duct, its exit direction,
and thus equal and opposite direction of the engine can be changed at will.

0 0 0
( ).
e e e e
F mV mV p p A
   
MUAV2
27


Visit us at
www.fit.edu/projects/muav2


Most of the aerodynamic theory presented here has not taken into
account any
energy losses such as friction. Some of the components of the aircraft that will be at a
disadvantage due to frictional effects are the fan engine, the fan thrust, the thrust
vectoring mechanisms, and the flight speed of the aircraft through t
he air. This translates
into several less than ideal parameters,
i.e.

available thrust, power output by the motor,
sensitive maneuverability, and flight speed. These losses must be addressed in order to
achieve the most efficient aircraft possible that i
s still able to carry out the proposed
functions. By analyzing an ideal mathematical model and then building and testing a
prototype to its specifications we can proceed to then fine
-
tune the aircraft until it works
properly.



Structural Math Model Consi
derations
:

(Coutinho)



As far as the structure of the craft is concerned, it is important that we ascertain
what factors must be taken into account when considering whether the craft will be able
to withstand the shear/stress forces, force couples and mom
ents that each member will be
under. However, owing to the fact that our choice of structure has not been made owing
to actual need of other data including that of the propulsion systems and actual
force/thrust generated, most of our ideas are currently as
sumptions that will have to be
made about the final craft.


Most
MUAV
s are restricted to a max airspeed of between 32
-
42 mph. This
restriction is a result of a variety of effects that might occur to the craft. For instance, one
such effect is the actual di
sintegration of the external shell of the craft that can occur due
to the velocity at which it is traveling. Therefore, an effective craft must be able to take
the stresses that would be placed on it by moving through the atmosphere. Depending on
weather c
onditions, the craft should also be able to withstand temperature changes,
atmospheric conditions including high moisture content and radiation. One of our current
suggestions is to get help in fashioning a carbon fiber skin for the craft. By integrating
t
his with a honeycomb structure, it would be possible to eradicate many problems that the
craft might face.


Added stress considerations must also be made on the various fan blades, joints,
and motor units. Since most of the stress will be concentrated in t
hese regions, it is
imperative that they be able to take the maximum effects of these stresses over a certain
period of time. Excessive and unbalanced torques and moments would also need attention
since they could cause the actual structure of the craft to

undergo a series of effects
varying from fracture to fatigue in the case of sudden temperature rise and changes.

All
the equations and principles that will be needed to effectively carry out any and all
calculations are listed on the next page.


Other det
ails that should be taken into consideration would also be the loading of
the actual craft along with its final weight. Not only would these play a considerable role
with the duration of flight time, they would also determine where the center of gravity of

the craft is and where the turning moments versus the pressure distribution of the craft is
at the maximum. Should the craft suddenly lose control and should impact occur with any
hard surface, the craft should be strong enough that it can take the impact

without
shattering or getting damaging
to the point of ir
-
recoverability
. The honey
-
comb structure
MUAV2
28


Visit us at
www.fit.edu/projects/muav2

would help in accounting for much of these impact forces. These are some of the
relations that we will probably have to use in making our force and stress c
alculations for
the structure of the craft.



Thermodynamic Analysis of Materials:

(
Brown
)



Considering the materials from a thermodynamic viewpoint, it can be seen that
their properties (namely the thermal conductivity) vary greatly. This presents a pro
blem
where a balance between too much and too little thermal conductivity must be achieved.


For this analysis, the following three materials were considered:




Aluminum (AL 2024 properties were used for analysis)



Fiberglass and Epoxy



Carbon Fiber


Alumin
um has the highest value of thermal conductivity with k=177 W/m*K.
This could benefit the design by dissipating heat from the internal mechanisms at a
greater rate. However, if the body of the vehicle were to overheat, it could damage any
electronics or
other sensitive equipment in close proximity to the outer shell. Introducing
a cooling system to the internal workings of the vehicle is a possibility, but it would be
simpler to choose a material with a lower thermal conductivity.

Fiberglass has the lowe
st thermal conductivity of the possible materials (k=0.04
W/m*K). While this would help to prevent the body of the vehicle from overheating and
thus damaging some of the onboard equipment, it also presents some new problems.
Fiberglass is commonly used a
s an insulator, which is not what is needed for this
application. Electronics equipment that is vital to the operation of the MUAV will need
to dissipate heat, and constructing the body from an insulator would inhibit that.
Therefore, fiberglass is not t
he ideal material to use.

Carbon fiber has a variety of values for thermal conductivity, depending on which
variety of fiber is used, ranging from k=14 to k=80 W/m*K. It can be seen that both the
highest and lowest values found for carbon fiber fall somew
here in the middle for the
values of the materials considered. This would make the carbon fiber the ideal choice of
material. While problems due to too much insulation or conduction may still arise, the
carbon fiber will be easier to deal with than eithe
r aluminum or fiberglass.


After examining the thermal properties of the three materials considered, and
taking into consideration the other properties discussed in this report, it is clear that
carbon fiber would be easier to work with than either aluminu
m or fiberglass.
Furthermore, the main propulsion unit will consist of an alcohol powered engine which
will be left partially revealed to the outside thereby creating an air
-
cooled system. Heat
sinks will also be employed to keep temperatures from increasi
ng drastically within the
craft itself.






MUAV2
29


Visit us at
www.fit.edu/projects/muav2

Materials and Manufacturing:
(Grelck
/
Brown
)



After analyzing three different possible materials to use for the final body
construction, namely aluminum, fiberglass, and carbon
-
fiber, it was decided that the ide
al
material for the intended task is a carbon
-
fiber composite body. Carbon fiber will offer
the greatest strength and stiffness possible while still remaining the lightest option out of
the three body construction materials. The following is a table of d
ata on all three
materials, indicating that carbon
-
fiber is the most effective choice:


Table
2
:

Material data for aluminum, fiberglass, and carbon
-
fiber

Material Type

Young’s Modulus
=
呥湳楬e⁓瑲t湧瑨
=
䑥湳楴y
=
=
⡐獩F
=
⡐獩F
=
⡧⽣L
3
)

AL 2024

10.6 * 10
6

68 *
10
3

2.80

Fiberglass

10.0 * 10
6

500 * 10
3

2.55

Carbon Fiber

42.3 * 10
6

770 * 10
3

1.78


When the data from the above table
are

analyzed, a

few conclusions can be
drawn.
When viewing the
3

different Modulus of Elasticity’s, it can be seen that the
carbon f
iber is by far the stiffest by a factor of four compared to aluminum and fiberglass.
This stiffness would be very important in the event of a crash. If the craft fell and the
outer shell was not stiff enough, the inner components may be crushed, renderin
g the
MUAV

grounded.

Upon analyzing the tensile strengths for each material, it is shown that while
fiberglass is nearly eight times as strong as aluminum 2024, carbon fiber is more that
eleven times as strong. This added strength is crucial for the dur
ability of the craft incase
of an accident.

Finally, the density of each material must be considered. When the data is looked
at, it can be noticed that aluminum is more than one and a half times as dense as carbon
fiber. Likewise, fiberglass is nearly o
ne and a half times as dense as carbon fiber. This
means that carbon fiber is by far the least dense material, and, therefore, is the lightest
material for the job.

Bye cutting down on the total weight of the outer body, more of the
total weight can be fo
cused on components such as the fan blades and the main engine.


We have already been notified by the Florida tech machine shop that we
will be able to use a small amount of the carbon
-
fiber already on campus at no charge to
our team’s expenses. This sm
all amount is all that will be necessary to complete the
entire outer body of the MUAV. Should this carbon
-
fiber donation from Florida Tech
come through, both our nominal and minimal budgets will be reduced.











MUAV2
30


Visit us at
www.fit.edu/projects/muav2

Power Source:

(Coutinho)


Selecting t
he right
engine

is a most critical task
;

not only is it important to find a
source with sufficient enough
horsepower
, but we must also take into consideration many
other factors such as:




Size



Weight

o

Gross weight

o

Rate of Weight change (with fuel usage)




Ca
pacity



Efficiency



Size and weight are two very crucial aspects that must be considered when
determining what would be the best engine to use for our craft. It is very important that
we optimize all of the necessary factors in order to obtain the right ba
lance of power and
weight. The fuel consumption rate is another important factor as it will define the length
of time that we can stay aloft. Efficiency comes into play in this matter as well.


Our reasons for trying to use an alcohol engine are (Ref. 4):

Pros:



Alcohol produces more power, specifically more mid range torque from 4,000 to
6,000 rpm. For higher rpm, gasoline produces more horsepower than alcohol.



An alcohol engine will run 40 or more degrees cooler than a gasoline engine.
Also, maintaining t
he engine temperature is easier and more precise with alcohol.



Alcohol can be used with nitrous (however, unless planned and designed
properly, this can be very dangerous).



Alcohol is far more consistent than gasoline. It is easier to maintain engine
tempe
rature plus it is less affected by temperature or barometric changes.


However there are some issues that make alcohol engines unpopular sometimes. These
are:

Cons:



Alcohol engines consume over twice as much fuel as a gasoline engine.



Alcohol in itself is
not corrosive; however, the tendency for alcohol to attract
moisture increases the chance of corrosion in an engine.



Alcohol like all fuels is dangerous to some extent. The inherent danger in alcohol
is its property of burning almost invisibly.


Of the pro
s and cons, one con that stands out is the fact that the alcohol engine
consumes twice as much fuel as a gasoline engine. The use of nitrous, to improve
efficiency is not a very feasible idea for us at this stage, although it has been tried a few
times. Ho
wever, the fact that alcohol will be more efficient within our rpm range may
make up for its loss of efficiency in other matter. Plus engine overheating is always a
very big problem as it can lead to the supports melting due to consistently high
MUAV2
31


Visit us at
www.fit.edu/projects/muav2

temperatur
es, and it might also affect both our instrumentation and other electronic
devices on the craft.


Currently, we are studying three main engines. They are:



WEBRA
SPEED .91
-
P5 AAR HELI ENGINE


Specifications


Displacement: 15.0 cc (.91 cu in)

RPM: 2200
-
16
000

Bore: 27.6 mm

Stroke: 25.0 mm

Weight: 590 g

System of Control: Front Intake

Liner Piston Set: AAR

Crankshaft: 9.5mm (5/16 in)

Price
:
$269.99


Figure
1
9
:

WEBRA

SPEED .91
-
P5 AAR HELI ENGINE



The Webra speed

.91
-
P5 AAR H
eli

E
ngine is manufactured in Aust
ria based on
plans from its German counterpart. Its features include awesome power for its small size,
and an all ball
-
bearing construction.

(Ref. 5)




WEBRA
SPEED .75 P5 AAR HELI



Specifications



Displacement: 12.0 cc (.75 cu in)


RPM: 2200
-
1800


Bore
: 25.2 mm


Stroke: 24.0 mm


Weight: 540 g


Price
:
$259.99





Figure
20
:

WEBRA
SPEED .75 P5 AAR HELI



The Webra
Speed .75 P5 AAR Heli is the new flagship of the Webra heli engine
line. It boasts plenty of power and torque for unlimited 3
-
D flying and is a
s easy to start
and tune as its lower displacement kin. Despite its larger displacement, the .75 would fit
most helis with no modifications. The .75 is also the only Webra Heli engine to feature
the precision of an Ultra
-
mix carburetor. The Ultra
-
mix emplo
ys an all
-
new design that
maintains constant needle settings throughout the power transitions normally associated
with 3
-
D aerobatics. (Ref. 5)

MUAV2
32


Visit us at
www.fit.edu/projects/muav2



SAITO
100 FA
-
AAC W/MUFFLER: QQ


Specifications







Displacement: 17.1 cc (1.0 cu in)

RPM: 9300
-
9900

Bore: 2
9.0 mm

Stroke: 26.0 mm

Weight: 580 g

Price
:
$279.99




Figure
2
1
:

SAITO
100 FA
-
AAC W/MUFFLER: QQ



Saito's FA
-
100 will turn an APC 14 x 8 prop 300 to 700 rpm more than either the
Saito .91 or O.S.

.
91. The Saito FA
-
100 is not just a punched out .91. It fea
tures a newly
tooled case that shares the mounting dimensions of the O.S.
.
91. This allows it to be used
with the many after
-
market engine mounts already available to fit this engine
. (Ref. 5)





O.S.

.32 SX Engine




Stock Numbers:






OSMG1940 .32 SX
-
H Non
-
Ringed


Stock Number: OSMG0532


Displacement: 0.319 cu in (5.2 cc)


Bore: 0.77 in (19.6 mm)


Stroke: 0.69 in (17.5 mm)


RPM: 2,000
-
22,000


Output: 1.2 bhp @ 18,000 rpm


Weight: 9.5 oz (270 g)


Price:
$149.99


Figure
2
2
: O.S. .32 SX
-
H Heli Eng
ine

The O.S is a r
edesigned
engine manufactured
for durability, with
a
"beefed
-
up"
crankcase, heat
-
sink head, con
-
rod and crankpin
. The l
arger front bearing and rear
bearing w/nylon retainer maintain smooth power delivery
.
Type 20C Carb features larger,
7.
5 mm throat and dual needle valve
s

stabilize hovering and add to top end power
. It is
e
asy to retrofit features same mounting dimensions and crankshaft thread size as the .32
FH
(Ref. 6)

MUAV2
33


Visit us at
www.fit.edu/projects/muav2


Of these four engines, the O.S seems to be the best especially conce
rning the rpm
that it can create although its fuel displacement rate is considerably as high as some of the
other engines under consideration. Furthermore, given the fact that it is much cheaper
than the two Webra engines, and yet has a much higher rpm tha
n the other engines makes
it the current outstanding candidate for our engine. One of the main cons however, is its
weight. However, there may be ways to offset for this considering that our thrust to
weight ratio will definitely be greater with the O.S. t
han with the Webra engines.



Control Mechanisms:
(Parikh)


According to the objectives, we will focus on controlling the vehicle for better
maneuverability once satisfying flight and stability is achieved. Gears, Cams & Links
will be used to enhance the m
otion of the vehicle and the integrated parts. Gears are used
in various machines where they perform several important jobs, but most important, they
provide a gear reduction system in motorized vehicles. This is handy as sometimes a
small motor spinning v
ery fast can provide enough power for a device, but not enough
torque. With gear reduction the output speed can be reduced while the torque is
increased. Gears also help in multi
-
directional rotation. We have conducted thorough
research into the different
types of gear that we can use within our craft. This was one of
the main goals that we set for ourselves during Fall 2003 since without the appropriate
gearing system, it is impossible for our craft to ever take
-
off. The actual gearing system
that will be
used along with the engines supports is talked about in the subsequent
section(Gear Configuration and Support). Spur, helical, bevel, and worm gears are the
preliminary types of gears that we will be considering according to their use.







Bevel Gears





Worm Gears



Helical Gears Spur Gears





Figure
2
3
: Different gear types

MUAV2
34


Visit us at
www.fit.edu/projects/muav2

Final Design
:

(Team MUAV)


The Final Design is the combined effort of all

the MAE team members and their
creativity. The design review, followed by the individual assembly designs are as
follows:


Design Review:
(Parikh)


The preliminary design reviews and numerous brainstorming sessions have resulted in an
immense amount of i
nput on the final design and has influenced every single curve of the
craft. For most of us, the design has a secret meaning and it fuels us up with confidence
every time we see it. The following detailed assembly design review briefs through the
CAD desig
ns, Engineering Drawings, Manufacturability, Electronics and Control
devices, and provides theories that support the designs. The MUAV design as a whole
can be divided into 4 major assembly levels including the CFA (Central Fan Assembly),
RFA (Rear Fan Ass
embly), LGA (Landing Gear Assembly), & SWA (Shroud & Wing
Assembly). The following figure shows the finalized MUAV design followed by the
design breakdown:





























Figure

2
4
: ‘MUAV’ SolidWorks Design by B. Parikh


MUAV2
35


Visit us at
www.fit.edu/projects/muav2


Design Breakdown



Figure

2
5
: ‘MUAV’ SolidWorks Design by B. Parikh

CFA

RFA

SWA

LGA

MUAV2
36


Visit us at
www.fit.edu/projects/muav2

De
tailed Assemblies
:


The Central Fan Assembly consists of two co
-
axial, counter
-
rotating propellers
that are powered by an internal combustion engine. These propellers are contro
lled by
gearing 2 co
-
axial shafts. The assembly detail is as follows:


C
e
ntral Fan Assembly (CFA)
:

(Parikh, Burger,
Brown
)


Designs: Parikh






Figure

2
6
: “MUAV’ Central Fan Assembly by Parikh




MUAV2
37


Visit us at
www.fit.edu/projects/muav2

ASSEMBLY SECTIONAL


Figure

2
7
: MUAV’ Central Fan Assembly Sectional View by Parikh




NOTE: Design Concept & Overview by
Brown

&

Parikh.










Bearing Housing

Bearings

Tractor Prop Hub

Outer Shaft

Collar

Inner Shaft

Closing Cap


Pusher Prop Hub

Support Ring

Bevel Gears

MUAV2
38


Visit us at
www.fit.edu/projects/muav2

EXPLODED VIEW



Figure

2
8
: MUAV’ Central Fan Assembly E
xploded View by Parikh



PART DETAIL


1.

CFA001


Closing Cap


2.

CFA006


Inner Bearings



3.

Linear Actuator


4.

CFA009


Bevel Gears




MUAV
2
39

Visit us at
www.fit.edu/projects/muav2


5.

CFA002


Pusher Prop



6.

CFA003


Inner shaft

7.

CFA004


Tractor Prop



8.

CFA005


Outer Shaft









MUAV
2
40

Visit us at
www.fit.edu/projects/muav2



9.

CFA007


Bearing Housing Cap




10.

CFA012


Bearing Housing Base



11.

CFA013


Support Ring


MUAV
2
41

Visit us at
www.fit.edu/projects/muav2


12.

CFA010


OS Engine



13.

CFA008


Collar




Figure

2
9
: MUAV’ Central Fan Assembly Part
s

by Parikh


MUAV
2
42

Visit us at
www.fit.edu/projects/muav2



Manufacturing
: (Grelck)



The construction of the central fan assembly, while it appears complicated will
actually be quite easy to do. The only aspects of the CFA that need
to be machined are
the two propeller shafts: the inner shaft, and the outer shaft. Also, since the shafts are
axis
-
symmetrical, there are no complicated machining tasks that cannot be done on a
precision lathe machine. Teknocraft, Inc. has also offered u
s the use of their CNC lathe
machine with their professional assistance for the manufacturing process of the two
shafts. By using the dimensions of the shafts already on the computer in SolidWorks, the
shafts drawings can be imported into a compatible sof
tware program read by the CNC
lathe at Teknocraft. Once the shafts are in the machine, and the cutting dimensions are
programmed, there is nothing left to do but start the CNC machine. This reduces the
possibility of a human error in the shaping of the s
hafts on a manual lathe such as the
ones at the Florida Tech Machine Shop.


Controls and Involved Electronics
: (Fernandez)



Controls needed: speed of engine

Electronics involved: signal from microcontroller will
control the servo motor attach to the mech
anical thrust
lever. This servo motor will be power with the
electronics board power supply.













Figure

30
: MUAV’ Central Fan
Assembly Microcontroller by Parikh

Mathematical Model of
C
FA
: (
Burger/
Brown
/Parikh
)


Thrust in terms of power input
:

(Burg
er)



The relevance of this calculation to the MUAV project is high. Since we know
the power output of the small gas engine we will be using, it will be pertinent to find an
equation for the thrust produced as a function of power input to the fan assembly
.


To begin, we will need to state the simplifying assumptions that will be used to
make the problem easier to solve. These assumptions are listed below.




Flow is incompressible



Isentropic Flow (adiabatic and reversible)



MUAV is moving at relatively low
speeds




The exit flow exhausts to ambient pressure



Change in temperature of the fluid is negligible



Change in height of the fluid is negligible


MUAV
2
43

Visit us at
www.fit.edu/projects/muav2


Control Volume
















Figure

3
1
:
Control volume around central fan assembly
.


Basic Principles



Conse
rvation of Mass:



.
const
UA
m





(1)




Conservation of Momentum:



)
(
)
(
e
i
e
i
e
p
p
A
V
V
m
F






(2)




First Law of Thermodynamics:





cv
b
a
b
a
b
a
cv
W
y
y
g
V
V
h
h
m
Q










)
(
)
(
)
(
2
2
2
1

(3)


Now we can start to simplify the basic principle equations using the assumptions that
we ma
de earlier. First, to validate the use of the conservation of mass, the assumption
that the flow is incompressible comes into play here. The second assumption takes
care of any losses in the system due to heat addition and friction by neglecting them.
T
he third and fourth assumptions simplify equation (2) by taking the second term in
the right member to zero and dropping out the inlet velocity component of the first
term. Equation (2) then reduces to



e
V
m
F


.

(4)



The second, fifth, a
nd sixth assumptions apply to the energy equation. Because it
is assumed that the flow is isentropic, and therefore adiabatic, the heat transfer term drops
out. Since the change in the temperature is assumed to be negligible, the enthalpy
components drop

out. Also, since the change in the height of the fluid is assumed to be
(m, U, p, A)
1

(m, U, p, A)
4



2

3

MUAV
2
44

Visit us at
www.fit.edu/projects/muav2


negligible, the gravitational potential energy component drops out. The equation (3) then
reduces to





cv
W
V
V
m




)
(
2
1
2
4
2
1
.

(5)


We can now solve equation (5) for the exit veloc
ity
V
4

in terms of the power
input, which is the right member of equation (5). The first assumption, namely that the
vehicle is moving at relatively low speeds can also be expressed as
V
4
>>
V
1
. In light of
this assumption, and solving for the exit velocit
y yields



m
W
V
cv


2
4

.

(6)



According to the conservation of mass, the mass flow rate into the control volume
equals the mass flow rate exiting the control volume. And, since we are assuming the
fluid is incompressible, the density of the fl
uid doesn’t change, so
4
4
A
U
m
UA
m








. After substituting for the mass flow rate and some minor
rearrangement, equation (6) becomes



3
1
4
4
2










A
W
V
cv


.

(7)


Since the exit velocity is equal to the velocity at station 4, we can now substit
ute equation
(7) into equation (4) to get



3
1
4
2










A
W
m
T
cv