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Page
1







ENGN8100
:

Introduction to System Engineering


Sub
-
System
:

Energy Conversion System






Name

Student ID

Mauricio Veloso

u4474096

Pouyan

Taghipour Bibalan

u
4422921

Brad

Stanford

u45
00144

Kw
an
-
Hoe,

Tay

u4376339

Nan

Yi

u4382406

Xu
efeng

Ye

U4466785

Ming Chen

u
4242754





Page
I


Abstract

With the final goal being
to

design an ecologically sustainable ultralight aircraft, it is
necessary to first gather a list of customer needs to ensure that the end product is able to
satisfy their requirements. A functional decomposition of the project is performed to
ensure each cr
itical aspect is analysed while still working towards a common goal.

The report details the importance of the customer needs in relation to the energy
conversion subsystem. The list of concepts generated for the sub
-
system will be described
and using the n
eeds
-
metrics matrix to screen and benchmark concepts which will be
eliminated if the requirements are not met.

The lifetime costs of an internal combustion engine and electric motor are analysed in the
form of a life
-
cycle analysis. The significance of su
ch an analysis is to compare the c
ost in
using either concept. The final selection criteria and subsystem specifications are detailed
with recommendations for future
improvements

being discussed at the end of the report.



ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

Page
II

FINAL REPORT

I.

TABLE OF CONTENTS

II.

List of
Figures

III.

List of
Table
s

1.

INTRODUCTION

1

2.

CUS
TOMER NEEDS

3

2.1

Customer needs hierarchy and importance

3

2.2

Metrics

4

2.3

Needs
-
Metrics
Matrix

5

2.4

Customer Needs Justification

7

3.

BENCHMARKING AND SPE
CIFICATION

7

3.1

Benchmark

7

3.2

Target Speci
fications

10

4.

FUNCTIONAL DECOMPOSI
TION

10

4.1

Functions of our sub
-
system energy conversion

11

4.2

Function analysis on sub
-
system level

12

4.3

Graphical representation of functional decomposition

13

4.4

Variations on functional decomposition

14

5.

CONCEPT GENERATION

15

5.1

Concept tree generation

15

5.1.1

Concept tree for the Conversion to Propulsion sub
-
subsystem

15

5.1.2

Concept tree for Storage Energy sub
-
subsystem

16

5.1.3

Concept Tree for the Energy Conversion to Stored Energy sub
-
subsystem

17

5.1.4

Concept Tree for the Conversion to Internal Energy sub
-
subsystem

17

5.2

Putting It Together: Concepts

18

5.2.1

Conventional internal combustion engine

19

5.2.2

Internal combustion engine(diesel)

19

5.2.3

Solar powered and solar powered with battery assistance

20

5.2.4

Jet engine

21

5.2.5

Fuel cell powered with battery assisted takeoff

21

5.2.6

Hybrid drive

22

5.2.7

Electric with rocket assisted take off

24

5.2.8

Human powered aircraft

25

5.2.9

Wind powered aircraft

26

5.2.10

Nuclear powered aircraft

27

5.2.11

Regenerative braking

28

5.2.12

Gravity powered aircraft

29

6.

CONCEPT SCREENING AN
D SCORING

30

6.1

Preliminary Concept Screening

30

ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

Page
III

FINAL REPORT

6.2

Concept Scoring

32

6.3

Further concept screening

33

6.3.1

Solar Powered and Fuel Cell power Elimination:

33

6.3.2

Jet Engine Elimination

34

7.

CONCEPT SELECTION AN
D JUSTIFICATION

34

7.1

Life Cycle Analysis


Internal Combustion Engine

37

7.2

Life Cycle Analysis


Electric Motor

38

7.3

Concept Recommendation

38

8.

CONCEPT DEVELOPING A
ND DESCRIPTION

39

8.1

Battery

39

8.1

Electric M
otor

41

8.1.1

DC motor

41

8.1.2

Torque motor

42

8.1.3

AC m
otor

42

8.1.4

Slip ring

42

8.2

Choosing the right motor

42

8.3

Design a new motor

43

8.3.1

Brushless motor basics

43

8.3.2

Final Design based on Antares 20E

43

8.4

Propeller selection/design specifications

44

8.4.1

Pitch and types of propellers

44

8.4.2

Propeller diameter

45

8.4.3

Number of blades

46

8.4.4

Material of blades

46

8.4.
5

Selecting criteria

46

8.5

Final Specifications

46

9.

RECOMMENDATIONS FOR
NEXT STEPS

49

9.1

Increase motor efficiency

49

9.2

Integrating with Fuel Cell and Solar Cell

49

9.3

Improved aerodynamic structure

50

10.

CONCLUSIONS

50

REFERENCES

52


ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

Page
IV

FINAL REPORT

II.
List

of
Figures


Figure 1: Scale to measure Importance

................................
................................
..................

4

Figure 2: Rotax 503

................................
................................
................................
.................

7

Figure 3: Rotax 912

................................
................................
................................
.................

8

Figure 4: EM
-
10

................................
................................
................................
......................

8

Figure 5: Black box of a sub
-
system

................................
................................
.....................

12

Figure 6: Functional Decomposition of Energy Conv
ersion Sub
-
system
..............................

13

Figure 7: Concept Tree for Propulsion System

................................
................................
.....

15

Figure 8: Concept Tree for St
orage System

................................
................................
..........

16

Figure 9:

Concept Tree for Energy Conversion to Stored Energy System

............................

17

Figure 10: Concept Tree for the Conversion to Internal Energy sub
-
subsystem

.................

17

Figure 11: S
unSeeker, Aircraft based on Solar power

................................
..........................

20

Figure 12: TRS
-
18 Turbojet Engine

................................
................................
.......................

21

Figure 13: Typical torque and horsepower curve for an

internal combustion engine

.......

23

Figure 14: Typical torque and horsepower
curves of an electric motor

.............................

23

Figure 15: Gossamer Albatross

................................
................................
.............................

25

Figure 16: Wind Power Generator

................................
................................
.......................

26

Figure 17: Nuclear Powered Aircraft Design Examples

................................
........................

27

Figure 18: The Gravity
-
Powered Aircraft


................................
................................
.............

29

Figure 19: Cost vs. Power comparison, Internal Combustion Engi
ne and Electric motor

...

36

Figure 20: Cost vs. Power/Weight comparison, Internal Combustion Engine and Electric
motor

................................
................................
................................
................................
....

36

Figure 21: Rotax 912

................................
................................
................................
.............

37

Figure 22

Lithium
-
ion

battery

................................
................................
...............................

39

Figure 23

Lit
hium polymer battery

................................
................................
.......................

39

F
igure 24

Lead
-
acid battery

................................
................................
................................
..

40

Figure 25

Nickel
-
metal hydride battery

................................
................................
................

40

Figure 26

Nickel
-
Cadmium battery

................................
................................
.......................

40

Figure 27

Hypothetical two
-
pole

three
-
slot brushless
motor

................................
.............

43

Figure 28

E
M4
2 42kW Brushless DC Motor

................................
................................
.......

44

Figure 29

Cost vs. Power for final design

................................
................................
.............

47

Figure 30

Weight vs. Power for final design

................................
................................
.........

48

Figure 31: Cost Analysis of Fuel Cells
................................
................................
....................

50







ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

Page
V

FINAL REPORT

I
I
I. List of Tables


Table 1: Mission
Statement: Ecologically Sustainable Ultra
-
light Aircraft

.............................

1

Table 2: Summary of System needs

................................
................................
.......................

2

Table 3: Detailed Customer Needs for Energy Conversion System

................................
.......

4

Table 4: List of Metrics

................................
................................
................................
...........

5

Table 5

Needs
-
Metrics Matrix

................................
................................
................................

6

Table 6: General Benchmark for Different Types of Engines

................................
.................

8

Table 7

Benchmarking table for 5 type energy conversion systems

................................
......

9

Table 8: Necessary functions t
o provide for energy conversion sub
-
system

......................

11

Table 9: Optional functions to provide for energy conversion sub
-
system

.........................

11

Table 10: Necessary functions required from other sub
-
systems

................................
.......

12

Table 11: Energy, material and signal flow of energy conversion sub
-
system

....................

12

Table 12

Concept Screening Table

................................
................................
.......................

31

Table 13

Selection Criteria for Energy Conversion System Selec
tion

................................
..

33

Table 14

Existing Solar Powered Ai
rcraft Specifications

................................
....................

33

Table 15

Cost Comparison of 5 different energy sources to generate one kW of energy

..

34

Table 16: Cost vs. power Data Set for Internal Combustion Engine

................................
....

35

Table
17: Cost vs. power Data Set Electric Motor

................................
................................

35

Table 18: Waste analysis for Internal Combustion Engine (Rotax 912)

...............................

37

Table 19

Motor specifications for some existing battery powered aircrafts

.......................

41

Table 20

Energy conversion Specifications for 3 set points

................................
.................

47





Page
1


1.

Introduction

The objective of this course is to develop an ultra
-
light aircraft which would be ecologically
sustainable while still appealing to the mass market. Like any other product, boundaries of
the project relating to
the target audience have to be set.


Mission Statement: Ecologically Sustainable Ultra
-
light Aircraft

Product
Description:

A safe, cost effective ultra
-
light aircraft that is suitable for
recreational flying by unlicensed pilots and emphasises ecologically
sustainable design principles as a method of market segregation.

Milestones:

1.

Defining Scope by 2
nd

April

2.

Draft Customer
Needs Gathered by 2
nd
April

3.

Breakdown and Allocation of Subsystems by 2
nd

April

4.

Establishing Importance of Needs within Sub
-
system by 9
th

April

5.

Further Decomposition of Subsystem by 9
th

April

6.

Identified Importance of Needs by 9
th

April

7.

Concept Generation b
y 30
th

April

8.

Subsystem Budget Allocation by 30
th

April

9.

Concept Screening and Recommendation by 7
th

May

10.

Concept Selection and Life Cycle Analysis by 21
st

May

Primary Market:

1.

Middle Income earners

2.

Active sports minded people

Secondary Market:

1.

Thrill
Seekers

2.

Flying Enthusiasts

Stakeholders:

1.

Users

2.

Retailers

3.

Manufacturers

4.

Sponsors

5.

Members in Design Team

Table
1
: Mission Statement: Ecologically Sustainable Ultra
-
light Aircraft



Summary of System needs

With the input from all the

subsystems, the following is the compiled list of the needs for
the project. Using these general needs of the system, each sub
-
system will study these
needs to determine how the needs of the project can be met by each sub
-
system.


ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

Page
2

FINAL REPORT


SYSTEM NEEDS

DESCRIPTIO
N

Structurally sound

The plane is able to handle the weight of all the
equipment.

Safe

Safety of the pilot is studied to ensure that in the
event of any emergencies, safety is not
compromised.

Convenient to launch

Is able takeoff on a short runway.

Low

Cost (running, capital service)

Cost of the entire system has to be within the
budget.

Offers independence in time, distance and
conditions for operation

Can travel a predetermined distance and
duration.

Pilot can navigate

With the help of technology, the pilot will be
able to determine his/her location in relation to
the destination.

Convenient to store and transport

It is lightweight and can be easily transported
between locations.

Fun to use

The pilot will enjoy the
experience of flying.

Communication

Communication between pilot and ground
controls crew is provided to receive/transmit
important information.

Easy to maintain

The system will not require extended durations
to check for faults.

Aesthetic / style / fash
ion

The outlook of the plane is pleasing to the eye.

Easy to operate

Controlling the aircraft should be as simple as
possible to cater to amateurs.

Good info feedback

Proper instrumentation is provided to inform
user of system information.

Reliable

System will not malfunction.

Comfortable

Vibrations and noise levels are minimized to
ensure pilot enjoys the experience.

Table
2
:
Summary of System needs

Description of Energy Conversion Sub
-
system

The energy conversion subsystem

creates the propulsion necessary and with the lift
created by the wings and structure of the aircraft enables the plane to take
-
off from the
ground.

The focus of this sub
-
system will be to generate concepts to provide the required amount
of thrust,
concepts generated include:




Internal Combustion Engine



Electric Motors



Jet Engines


ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

Page
3

FINAL REPORT

As well as means to store energy:



Petrol



Batteries


The advantages and disadvantages of the generated concepts will be
analysed

and
through a series of selection

criteria such as the needs
-
matrices matrix, concepts which do
not meet cost and weight limitations of the project will be eliminated.

2.

Customer Needs

In this section t
he complete list of customer needs for the Energy Conversion Sub
-
system
will be
presented. Also, will be indicated how those needs will be measure (Needs
-
Metrics
Matrix).

2.1

Customer needs hierarchy and importance

In the introduction chapter
,

a list of the
customer needs for the
overall system was
presented. Based on this list and on a c
omplete analysis of interactions with other
subsystems
,

a detailed list of customer needs for the Energy Conversion Sub
-
system was
generated
. The subsystem interaction needs are quite important for our subsystem

(in
general, for every sub
-
system)

because
,

our subsystem is a
part

of the whole system, and

there are relationships and impacts between the system’s components (sub
-
system).

At the beginning of the process, the data from customer
s

had to be converted in term
s

of
customer needs, i.e. assuring that t
he needs are expressed in terms of “what” the system
do
es
, being specific, describe the need as an attribute of the product, establishing positive
sentences and avoiding “must” and “should”

[
1
]
.
To establish the relative importance of
the needs we relied o
n the consensus and experience of the team member
s

and not on
feedback from real customers. The reason was

basically the time and cost constraint.

The
following are the needs organized in a hierarchy with the relative importance:

ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

Page
4

FINAL REPORT


Table
3
: Detailed Customer Needs for Energy Conversion System


The importance measure is based on scales of
Figure 1
.

The needs for the sub
-
system serve as a unified
understanding of customer needs among members
of the group and will be the base for product
specifications and selection criteria in the following
steps
of the product design process.




2.2

Metrics

To measure the degree to which our concepts, and our

product
, satisfy the customer
needs
,

a precise and measurable set of metrics

was generated
.

Table 4

contains

the metrics along with the customer
needs
associated

with them
and the
unit used to measure the needs:

#
Imp
Ranking
The Energy Conversion system is efficient
1
The Energy Conversion maximize the power/weight ratio
2
4
2
The Energy Conversion provides a powerful thrust generation
3
17
The Energy Conversion system has a simple and robust design
3
The Energy Conversion system has a long life time
2
9
4
The Energy Conversion system is easy to maintain
3
13
5
The Energy Conversion System is easy to start
3
13
The Energy Conversion system provides measurements interfaces for important measurements
6
The Energy Conversion system provides performance measures
2
11
7
The Energy Conversion system provides safety measures
2
11
The Energy Conversion system is compatible with other subsystems
8
The Energy Conversion minimize the noise (does not interrupt comunication, does not diminish the pilot confort)
3
16
9
The energy Conversion minimize electromagnetic fields
3
17
10
The Energy Conversion has low friction
3
19
11
The Energy Conversion minimize vibration
3
19
12
The Energy Conversion keep the balance of the Aircraft
2
9
13
The Energy Conversion system is suitable to structure of the aircraft
3
15
14
The Energy Conversion system enable to control the thrust (stop, acceleration)
2
1
The Energy Conversion system is safe
15
The Energy Conversion system is protected against fire and water (enclosure)
2
7
16
The Energy Conversion does not catch fire or explode
2
1
17
The Energy Conversion system has a safe energy storage
2
3
18
The Energy Conversion system has a back up energy unit for security reasons (redundancy)
4
22
19
The Energy Conversion system is robust to a wide variety of environmental conditions
3
21
The Energy Conversion system is ecological sustainable
20
The Energy Conversion system minimize the level of smell experienced by the pilot
4
22
21
The Energy Conversion system minimize the level of pollution to the environment
2
7
The Energy Conversion system is economical
22
The Energy Conversion System is economical to buy
2
4
23
The Energy Conversion System is economical to run
2
4
Subsystem Customer Needs: Energy Conversion
1.

Extremely Important

2.

Very Important

3.

Important

4.

Ambiguous

5.

Not Very Relevant

6.

Not Important

7.

Not Required at all

Figure
1
: Scale to measure Importance

ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

Page
5

FINAL REPORT


Table
4
: List of Metrics

2.3

Need
s
-
Metric
s

Matrix

After identifying the metrics
,

“Needs
-
Metrics Matrix

Table
” is developed which
further
indicates

the metrics and the customer needs that they address based on
Table 4
.

Table 5

is the Needs
-
Metrics Matrix developed for the energy conversion subsystem.


Metric No.
Need Nos.
Metrics
Units
1
2
Efficiency
% (Percent)
2
1,2,13
Power to weight
HP/Kg (Horse Power per Kilogram)
3
3,4,17
Mean Time Between Failure
Years
4
4
Number of part suppliers
# (List)
5
4
Cost of parts
AUD$ (cost)
6
4
Specialised tools required
# (List)
7
4
Time to perform servicings
Hours
8
5
Time to start
Seconds
9
8
Noise level within Pilot accomodation
dB
10
9
Electric field strength
Volts per meter (V m-1)
11
9
Magnetic field strength
Teslas (SI units)
12
10,13,15,16
Rate of Heat transferred
Watts (W=J/s)
13
10,13,15,16
Heat generated
J (Joule)
14
12,13
Change in location of Centre of Gravity
Cm
15
3,15,19,21
Aviation environmental testing
Binary
16
3,13,15,16,17
Temperature required to cause failure
°C (Celsius Degree)
17
3,16,17
Power draw required to cause failure
HP (Horse Power)
18
3,11,13
Aviation vibration testing
Binary
19
18
Length of time back up energy source remains operational
Mins
20
20
Amount of hazardous substance in pilot accomodation
PPM (Parts per Million)
21
15,16
Enclosure fire resistance
Fire-Resistance rating
22
9
Voltage rating of the Reg/Rec
Volts
23
9
Current rating of the Reg/Rec
Ampers
24
2,14
generated torque
N m (Newton Meters)
25
10
Modal test
Binary
26
2
Pressure test
Binary
27
22
Cost of the whole subsystem
AUD$ (cost)
28
6.7
Numbers of sensors
# (Numbers)
29
13
Dimension of the engine
cm x cm x cm
30
1,13
Weight
Kgs
31
23
Cost per flight hour
AUD$ (cost)
ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

Page
6

FINAL REPORT





1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Efficiency
Power to weight
Mean Time Between Failure
Number of part suppliers
Cost of parts
Specialised tools required
Time to perform servicings
Time to start
Noise level within Pilot accomodation
Electric field strength
Magnetic field strength
Rate of Heat transferred
Heat generated
Change in location of Centre of Gravity
Aviation environmental testing
Temperature required to cause failure
Power draw required to cause failure
Aviation vibration testing
Length of time back up energy source remains operational
Amount of hazardous substance in pilot accomodation
Enclosure fire resistance
Voltage rating of the Reg/Rec
Current rating of the Reg/Rec
generated torque
modal test
pressure test
Cost of the whole subsystem
Numbers of sensors
Dimension of the engine
Weight
Cost per flight hour
1
Maximize the power/weight ratio
X
x
2
Provides a powerful thrust generation
X
X
x
x
3
Has a long life time
X
X
X
X
X
4
Is easy to maintain
X
X
X
X
X
5
Is easy to start
X
6
Provides performance measures
x
7
Provides safety measures
x
8
Minimize the noise (comunication, pilot confort)
X
9
Minimize electromagnetic fields
X
X
x
x
10
Has low friction
x
X
x
11
Minimize vibration
x
12
Keep the balance of the Aircraft
X
13
Is suitable to structure of the aircraft
X
x
X
X
X
X
x
x
14
Enable to control the thrust (stop, acceleration)
x
15
Is protected against fire and water (enclosure)
x
X
X
X
x
16
The Energy Conversion does not catch fire or explode
x
X
X
X
x
17
Has a safe energy storage
X
X
X
18
Has a back up energy unit for security reasons (redundancy)
X
19
Is robust to a wide variety of environmental conditions
X
20
Minimize the level of smell experienced by the pilot
X
21
Minimize the level of pollution to the environment
x
22
Is economical to buy
x
23
Is economical to run
x
Needs
Metrics
Table
5

Needs
-
Metrics Matrix

ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

Page
7

FINAL REPORT

2.4

Customer Needs

Justification

To
validate

the completeness of our customer needs,
we have to confirm that
these needs
satisfy
,

at least
,

the gener
al requirements of our mission. In our case
,

we could
affirmatively say that our sub
-
systems needs
,

cover the main attributes declared in our
mission: safe
ty

(needs number
15, 16, 17 and 18)
, cost effective
ness

(needs number 22
and 23, an also needs 3 and 4)
, suitability

for recreational flying

(needs number
10, 11, 14
and 19)

and ecological sustainabil
ity emphasis

(needs number 20 and 21)
.

The emphasis is on

the “
ecol
ogical
sustainability”

need,
the need that
addresses

the
Energy Conversion
System minimization of

the level of pollution to the

en
vironment. This
need has an importance value of 2, and is w
ithin the seven more important needs of our
sub
-
system.

As will be establish
ed

later
, the cost of our sub
-
system is about 30% of the total cost of the
system.
Considering also that our target market is middle class families
,
it
is very
important to
be

a
war
e of the needs
concerning

cost. In our sub
-
system, the needs that
address cost have

an importance value of 2, which reflect
s

the

high
influence

of this
variable in the final decision.

Regarding

the less important needs
,

we
can

say that
it
is perfectly
aligned with our target
market and project purpose.

Even though

it

is good to have a sub
-
system that has, for
example, low friction, low vibration and easy to start

engine
, those

needs

are not the
characteristics
that contribute more to the mission’s attri
butes stated above. So, it is
reasonable that these needs be

of
less

importance
, i.e. have less discriminative power
than the other variables
, when decision about a particular concept has to be made
.

3.

Benchmarking and Specification

3.1

Benchmark

A good benchma
rk measures

the customer needs according to the metri
cs established for
the subsystem
. Of course, in our case
, we could not

buy and test
all the
criteria

of

the
energy conversion subsystem
. The ways we
carried out our benchmark, were

based
on
popular
comparison criteria on available data such as
cost, fuel consumption and power/weight ratio.

We will give a brief explanation of each type of eng
ine
used in our benchmark and in

the end
present
a
summary table comparing the major metrics available.

Rotax

503 and 447.

2 cylinder, 2 stroke fan cooled
engine with piston ported inlet, with electronic single
-
ignition (503 dual ignition)
,

exhaust system,
carburetor
,
rewind starter

[2]
.

Figu
re
2
: Rotax 503

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Rotax 912
.
The Rotax 912 has 4 cylinder, 4 stroke
liquid/air cooled engine with opposed cylinders, dry
sump

forced lubrication with separate oil tank,
automatic adjustment by hydraulic valve tappet, 2

c
arburetors

mechanical fuel pump, electronic dual
ignition, electric starter, propeller speed

reduction unit,
engine mount assembly, air intak
e system, and exhaust
system

[
3
]
.

Rotax engines are

the most popular
engines
in the
ultralight aircraft market.

Some

ultralig
h
t
aircraft
s

using Rotax

engines are
:
Tanarg 912

[
4
]
,
Piper J
-
3

[
5
]
, Clipper 912

[
4
]
, the BushCaddy R80 M
odel

[6]

and the Esqual Vm
-
1

[7]
,
between one of the

most popular.

TRS 18 Turbojet.

The Microturbo TRS 18
-
1 is certified
and it’s been in use for over

20 years in the airshow

Microjets. It uses a particular type of fuel, the Jet Fuel:
Jet A, JP
-
4 or JP5. At max power has a

consumption of
47.2 gal./hr., which make
s

it very expensive to run

[
8
]
.

EM
-
10
. Aluminum 4 cylinder, in
-
line diesel engine
, 2
valv
es/
cylinder, DOHC, common rail injection system,
turbo charged, water cooled

[9]
.

Electraflyer.
El
ectric engine capable of providing

155
pounds
(690 N)

of thrust.

It uses a lithium
-
polymer
battery that could be charged in 2 hour
s

[
10
]
.

Table 6
is a compiled list
of
data collected for the engines and motors which are used in
some
existing
ultralights:


Table
6
: General Benchmark for Differen
t Types of Engines

Type
Model
Output Power
Energy Source
Weight
Fuel
Consumption
Assumed Fuel
Price
Price
Life span of
equipment
Internal
Combustion
Engine
Rotax 447
29.5 kw (40
HP)
31.4kg
20.9Litres/hr
$5,877
4000 h
Internal
Combustion
Engine
Rotax 503
34.30kw
(46HP)
31.4kg
24.1Litres/hr
$7,046
4000h
Internal
Combustion
Engine
Rotax 912UL
59.6Km
(81HP)
55Kg
23.8Litres/hr
$14,499
4000h
Jet Engine*
TRS-18
TURBOJET
890N -1780 N
Jet Fuel (Jet A,
JP4-JP5)
38.5 kg
178.4 Litres/hr
$0.889/Litre
$50,000
-
Diesel
EM-80
52.20kW
(70HP)
Diesel
96kg
10.3 litres/hr
$1.70/Litre
$19,062
5000 h
Electric Motor
electraflyer
13.43kW(18H
P)
Electricity
40 kg
13.43kw/hr/90%
motor efficiency
$0.1/kwh
$7,157
1500 h
Regular
gasoline,
octane not
below 90
unleaded
$1.44 / Litre
Figure
3
: Rotax 912

Figure
4
: EM
-
10

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Based on the data in
T
able
6

and group’s intuition and research on the existing products
we came up with
Table
7
,

benchmarking 5 types of energy conversion systems against 8 of
the most important customer needs:



Petrol
Engine

Diesel
Engine

Electric
Motor

Hybrid

Jet
Engine

Safe to operate

•••

•••

••••

••



Lightweight

•••

••

••••

••



Comfortable

•••

••

••••





Easy to operate

••

••

•••





Easy to maintain

••

••

••••

••



Low in cost

•••

••

••••

••



Reliable

••••

••••

•••••

••

••

Fun

••



••



••••

Eco sustainable

••



••••

•••



Table
7

Benchmarking table for 5
type
energy conversion systems











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3.2

Target
Specifications

I
n terms of
target
specifications
,

3
constraints

were

defined in our project

for the Energy
Conversion System
:

Since there are several, totally different, existing energy conversion systems with a wide
range of power, power/weight ration, price, etc. it is not possible to define rigid target
specifications for the specified
metrics in an early stage. Choosing a specific kind of energy
conversion system will enforce restrictions for the various metrics. For instance, if we
choose a battery powered energy conversion subsystem we are bound with building the
aircraft with a light
er weight compared with an internal combustion engine.

During the course, the whole class reached a consensus over the following specifications:



Bu
d
get
.
Lower boundary of $8,194 and a upper boundary of $14,750
(35% of the
whole budget)



Weight
.

Between 80Kg
and 150Kg. The whole aircraft weight has to be within
200Kg and 500Kg.



Power.


After a discussion with the aerodynamic group we were advised of the
need of at least 5
kW

motor for generating the drag to lift a 200 kg aircraft.


4.

Functional Decomposition

Functional decomposition refers broadly to the process of resolving a functional
relationship into its constituent parts in such a way that the original function can be
reconstructed (i.e., recomposed) from those parts by function composition. In general,
this process of decomposition is undertaken either for the purpose of gaining insight into
the identity of the constituent components (which may reflect individual physical
processes of interest, for example), or for the purpose of obtaining a compressed
r
epresentation of the global function, a task which is feasible only when the constituent
processes possess a certain level of modularity (i.e., independence or non
-
interaction)

[1]
.

To explain it in the context of this project, functional decomposition fir
stly helps to clarify
the problem. In this specific case, it gives a functional pict
ure of the sub
-
system and helps
us understand
the
energy conversion system
in more depth,
both externally and
internally.

Externally

such as

how the sub
-
system interacts wi
th other sub
-
systems, what functions or
services the sub
-
system provides to others and the whole aircraft, and what
are
the
dependencies of the sub
-
system
; and
Internally such as

the component

relationships
between each other within the sub
-
system, what fu
nctions or services each component
provides to other components within the sub
-
system, and the dependencies of each
component on others.

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Additionally, it lays the strong foundations for the future work of concept research,
concept generation, concept scree
ning, and concept selection during the design process.
The future work about concepts thus has something to base on.

Moreover
, functional decomposition could also serve to map functions to physical
components, thereby ensuring that each function has an ack
nowledged physical owner, to
map functions to system requirements, and to ensure that all necessary functions are
listed and that no unnecessary functions are requested.
Table 8, 9

and
10
show these sets
of dependencies.


4.1

Functions of our sub
-
system energy

conversion

First we look at the functions from
the system point of view,

i.e.

what services or functions
other sub
-
systems and the whole aircraft
expect from our subsystem
, and what we want
from them.

Necessary functions to provide:

Function description

T
o which sub
-
system

Explanation

To generate thrust or
propulsion to lift the aircraft

Aerodynamic
structure

sub
-
system

The basic physics concept, to
overcome the gravity and drag
force.

To provide interface to control
the energy conversion sub
-
system

Control

sub
-
system

The pilot needs to control the
direction and/or quantity of
the thrust or propulsion.

To provide interface to
measure parameters needed
during flight

Communication and
instrumentation

sub
-
system

The pilot needs to know critical
flight p
arameters, e.g., engine
running speed

Table
8
:
Necessary functions to provide for energy conversion sub
-
system

Optional functions to provide:

Function description

To which sub
-
system

Explanation

To provide electricity power
for
movement of aerodynamic
structure

Aerodynamic
structure sub
-
system

The movement of flaps on the
wings could be driven and
powered by electricity.

To provide electricity power
for control instruments

Control sub
-
system

The control sub
-
system may
need elect
ricity power.

To provide electricity power
for communication and
instrumentation instruments

Communication and
instrumentation sub
-
system

The instruments may need
electricity to power the
instruments.

To provide electricity power
for pilot accommodation
instruments

Pilot accommodation
and protection sub
-
system

Pilot seat could be electrically
adjusted; air conditioning may
installed.

Table
9
:
Optional functions to provide for energy conversion sub
-
system

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Necessary functions
required from other sub
-
systems:

Function description

To which sub
-
system

Explanation

Provided some room or space
to place the physical energy
conversion sub
-
system
components

Aerodynamic
structure sub
-
system

We need to mount the engine
on the aircraft

Table
10
:
Necessary functions required from other sub
-
systems

Optional functions needed from other sub
-
systems:

None

4.2

Function analysis on sub
-
system level

First, we start
ed

with a black box model illustrated
in
Figure 5

and then cam
e up with the
functional decomposition of our subsystem (
Figure 6
).







Input

Output

Energy

Stored or converted energy on board

Kinetic energy

Material

Energy source material, e.g. chemical
fuel, etc

Decomposed material from energy
source material

None, e.g. wind power, solar power,
etc

N/A

Signal

N/A

Instrumentation signal

Pilot
controlling signal

N/A

Table
11
:
Energy, material and signal flow of energy conversion sub
-
system

Function description on sub
-
system level

Energy:

energy from sources, either stored on board prior to flight, e.g., in the form
of
fossil fuel or electricity, or converted on board, e.g., solar power or wind
power goes into the energy
-
conversion sub
-
system and then is converted
to kinetic energy to power the aircraft.

Material:

in some cases, the material input goes into our sub
-
syste
m, and then is
consumed and decomposed after energy stored in it is released and
converted.

Energy
Conversion
sub
-
system

Energy

Material

Signal

Energy

Material

Signal

Figure
5
: Black box of a sub
-
system

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Signal:

signal to control engine initiated by the pilot, via controlling sub
-
system,
transmits to our sub
-
system, and our sub
-
system reacts consequently. At
last, t
he control signal terminates and disappears. Another type of signal
for measuring some important parameters, e.g., fuel left in the tank, engine
running speed, etc, is generated within our sub
-
system, then output to
instrumentation sub
-
system.




4.3

Graphical

representation of functional decomposition
















There are 4 components of energy
-
conversion sub
-
system:

a)

Conversion to stored energy

b)

Conversion to propulsion

c)

Energy
storage

d)

Conversion to internal energy

Control
signal

Fuel waste

External Energy

Conversion to
stored energy

Energy storage

Conversion to

propulsion

Conversion to
internal energy

Instrumentation signal

Energy:

Material:

Signal:

Figure
6
: Functional Decomposition of Energy Conversion Sub
-
system

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We realized
energy

conversion sub
-
system with

different energy sources
, can be
illustrated in different ways
, but
Figure 6

was
the
best one we came up with that could

cover
different concepts, inc
luding jet engines, co
nventional

internal combustion engines
or diesel engines, rocket engines, solar powered engines, man powered engines or

electric
motors. At the time we

created
Figure
6
, we took a great many of concepts in existence
into consideration.

4.4

Variations on functi
onal decomposition

For some concepts and implementations of
an
aircraft,
some

parts of
Figure 6

may not
exist.

The following paragraphs explain some var
i
ations of
Figure 6
.



Solar
-
powered aircraft

Generally, energy conversion sub
-
system in this type of
aircraft contain
s all 4 components
of

Figure 6
:

Conversion to stored energy, Conversion to propulsion, Energy

storage and
Conversion to internal energy.


During flight, solar energy is converted by solar panel to electricity energy and stored into
battery.

Then the energy in the battery is converted to propulsion by electric motor and
propeller. Part of
the
electric energy is
output
ted to operate instruments on board
.



Internal combustion engine aircraft

Basically
, energy conversion sub
-
system in this type o
f a
ircraft contains 3 components of

Figure
6
:

Conversion to propulsion, Energy

storage and Conversion to internal energy.

Energy stored in the fuel tank is converted to propulsion by engine and propeller. Part of
energy stored in the fuel
tank is converted

to electrical

energy and output
ted

for
ins
truments on board
.



Man
-
powered aircraft

There is only one

component in
Figure
6

for the energy conversion sub
-
system in this type
of airplane, i.e., Conversion to propulsion.

In this kind of aircraft, the pilot
pe
d
als to run the propeller, similar to the way of pedaling
a bicycle; meanwhile the propeller provides

propulsion.



Aircraft without instruments requiring internal energy

This kind of aircraft could use any kind of energy source mentioned above, and the
major
difference is that this kind of aircraft does not need the component of Conversion to
internal energy to supply electricity for the instruments on board. This could be due to
either instruments on board not needing electricity to run or instruments h
aving their own
power supply, e.g., portable battery included in the instruments.


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5.

Concept Generation

5.1

Concept tree generation

As mentioned in the last chapter we

have 4

sub
-
subsystems

to explore different concepts
relating to each of the sub
-
sub
-
systems. A
fter discussing many different options, the
group decided that the easiest way to start would be to draw up concept trees and see if
any branches could be pruned at this early stage

for every sub
-
subsystem
.

5.1.1

Concept tree for the Conversion to Propulsion sub
-
subsystem



The group decided that steam engines may be able to be eliminated at this point in time.
A small amount of research was conducted and the group discovered steam engines came
in several different styles:



Steam
Turbine



Steam Piston



Steam Rocket

The steam turbine and steam piston engines are generally used for power generation on a
large scale. They require water to be heated then fed into the engine to turn the rotors of
an electric engine. This could be adapted
to turn the propeller of an aircraft; however, the
weight penalty is very large. It was decided that these concepts were unfeasible.

Conversion to
Propulsion

Jet

Internal
Combustion
Engine

Pedals

Electric
Motor

Steam
Engine

Rockets

Gasoline

Hybrid

Diesel

Traditional
Propeller

Ducted Fan

Gas

Figure
7
: Concept Tree for Propulsion System

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The steam rocket is an interesting concept that requires further investigation. This has
been combined with the more genera
l Rocket Motor class of propulsion generation.


5.1.2

Concept tree for Storage Energy sub
-
subsystem



The group considered all of these storage options and applied some pragmatic thinking to
decide which concepts were unfeasible. Research showed that batteries have
higher

power density storage than capacitors and are much cheap
er per
kW
h to use than
capacitors
. Capacitors cannot store large amounts of energy like a battery can. For this
reason, the capacitor was eliminated as a power source in
favor

of a battery.

Energy stored in a mechani
cal fashion, as described in
Figure 8
, is good for actuating
ob
jects for small lengths of time. These types of stored energy have the ability to deliver
high power; however, that power cannot be sustained and the stored energy is quickly
depleted. Clearly, the aircraft needs to sustain power over a large length of tim
e;
therefore, the mechanically stored energy sources were eliminated from consideration.

Thermo
-
electric energy converts heat directly into electricity. The group could not think of
a feasible way to implement this effect in order to drive a propeller or t
urbine.
It was
eliminated from consideration on this basis.


Store Energy

Chemical

Electrical

Nuclear

Mechanical

Heat

Liquid
fuels

Gaseous fuels

Solid Fuels


Thermo Electric

Phase change
(Steam)

Battery

Capacitor

Pneumatic

Spring
Tension

Flywheel

Hydraulic

Figure
8
: Concept Tree for Storage System

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5.1.3

Concept Tree for the Energy Conversion to Stored E
nergy

sub
-
subsystem













As mentioned in the Functional Decomposition chapter, these alternatives
depend

on

the
actual solution

and some are optional to any solution
.


5.1.4

Concept Tree for the Conversion to Internal Energy sub
-
subsystem

The (battery) option
refers just to the use of the same battery of the Stored Energy sub
-
subsystem, for example, the case of the Electric Motor solution.

Gather Energy

Solar

Air Flow

Regenerative
Braking

Human Power

Photovoltai
c

Heat

Hydraulic
generator

Electrical
Generator

Pneumatic
generator

Hydraulic
generator

Electrical
Generator

Pneumatic
generator

Hydraulic
generator

Electrical
Generator

Pneumatic
generator

Storage

Figure
9
: Concept Tree for
Energy Conversion to Stored Energy

System

Conversion to
Internal Energy

(
Battery
)

Alternator +
Battery

Figure
10
:
Concept Tree for
the Conversion to Internal Energy sub
-
subsystem

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The Alternator plus the Battery refers as an independent solution to provide internal
energy, for example, the case of an I
nternal Combustion Engine.

5.2

Putting It Together
: Concepts

After discussing the pros and cons of the concept trees, the group decided that, in order
to move forward, the next step would be to generate some concepts. There are many
combinations that can be ma
de from the concept trees above, so the most promising
concepts were put forward and analysed further. Listed here are the concepts that the
group decided held the most merit, along with several concepts that, at first glance may
be considered unfeasible;
however, must be put to the project as a whole in order to
dismiss.



Conventional internal combustion engine



Internal combustion engine (diesel)



Hybrid Drive (Prius Technology)



Jet engine



Solar Powered and Solar Powered with Battery Assistance



Fuel Cell Pow
ered with Battery Assisted Takeoff



Electric with rocket assisted take off



Human powered aircraft



Wind powered aircraft



Nuclear powered



Regenerative braking (applies to all concepts above)



Gravity Powered Aircraft


Block diagrams and a short description of each concept were then developed by the
group.

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5.2.1

Conventional internal combustion engine


The conventional internal combustion engine is well known to most people. The block
diagram shows the most common setup of t
he internal combustion system, which
converts fuel to mechanical energy by burning it. The mechanical energy is then converted
to propulsive force by turning a propeller and electrical energy by turning the rotor of the
alternator. This is a well

establish
ed technology.


5.2.2

Internal combustion engine(diesel)


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The diesel engine has been included as a separate concept as popularity with diesel is
increasing. The motor vehicle industry has shown that modern diesel engines can be made
to run very efficiently and
may even be a more cost effective option than a gasoline
engine. They do generally come at the expense of higher weight and initial cost; therefore,
may prove to be uncompetitive on that front.

5.2.3

Solar powered and solar powered with battery assistance



At
this point in the concept generation phase, the group considers the solar aircraft one of
the forerunners for selection, based on the perception of low environmental impact
during operation. Shown here is the “SunSeeker” aircraft, which is a sailplane desi
gned to
fly on solar power.



Figure
11
: SunSeeker, Aircraft based on Solar power

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5.2.4

Jet engine



The TRS
-
18 Turbojet Engine is shown here. The most common configuration

is to install
two of this size engines onto a light aircraft to generate sufficient thrust for flight.


5.2.5

Fuel cell powered with battery assisted takeoff


Figure
12
: TRS
-
18 Turbojet
Engine

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Fuel cells are an emerging technology that does not currently appear feasible for
production aircraft
. Boeing
has

demonstrated the ability to design and build a fuel cell
powered aircraft; however, their concept aircraft still requires battery assist for take
-
off.

5.2.6

Hybrid drive



A hybrid vehicle is a vehicle that uses two or more distinct power sources
to propel the
vehicle. The most commonly used hybrid energy conversion system is hybrid
-
electric,
which is constructed of an internal combustion engine with an electric engine assist. These
types of hybrid energy conversion systems are highly
favored

becau
se the fuel source is
already readily available. No costly efforts are required in order to establish readily
available fuels.

The hybrid
-
electric energy conversion system is able to take advantage of the pros of both
the internal combustion and electric
motor power curves, while reducing the cons. As
shown in

Figures 13 and 14
, an electric motor has high torque at low rotational speeds
and low torque at high rotational speeds. Conversely, the internal combustion engine has
low torque at low rotational spe
eds and high torque at high rotational speeds. The hybrid
-
electric drive system aims to combine these two curves in a mutually beneficial way.

The main disadvantage of performing this combination of two different drive systems is
quite a noticeable penalty

in weight.

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Figure
13
: Typical torque and horsepower curve for an internal combustion engine

[
11
]



Figure
14
: Typical

torque and horsepower curves of an electric motor

[
11
]

On the other hand we have “
Hybrid fuel”
engines that

can use different fuel types.
These
can be broken into two categories:

1.

Flexible Fuel engines are able to use two or more fuels mixed together in the same
fuel tank. For example, an engine may be able to run on petroleum, ethanol o
r any
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mixture of the two. The advantage is that the user may select whichever fuel suits
at the time of purchase.


2.

Dual Mode engines are similar to Flexible Fuel engines in that they can run on two
or more different fuels. However, unlike the Flexible Fuel

engines, the two
different fuels cannot be mixed. These engines have the advantage that the user
may select the fuel that is most appropriate at the time of purchase; however, it
requires the use of multiple fuel tanks, which adds weight and volume.


5.2.7

Electric with rocket assisted take off



This is most applicable to aircraft wishing to perform tranist flights only. An aircraft utilises
more power taking off than in any other phase of flight. A much smaller electric motor
would be required if the prop
eller drive system only needed to sustain altitude. The rocket
assist would allow a once a flight boost to the take off and climb phase of the flight.







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5.2.8

Human powered aircraft



This technology has been demonstrated by the Gossamer series of aircraft.

Shown below
is the Gossamer Albatross, which was the first pedal powered aircraft to cross the English
Channel. Although it is kind of neat, it probably would not be considered a recreational
aircraft.



Figure
15
:
Gossamer Albat
ross




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5.2.9

Wind powered aircraft



This concept is not meant to be used as a primary power source. Many aircraft use this
concept as an emergency backup power source for the onboard instrumentation. The
wind generators are shown in the two pictures below.


Figure
16
:

Wind Power Generator






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5.2.10


Nuclear powered aircraft




Figure
17
: Nuclear Powered Aircraft Design Examples




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5.2.11


Regenerative braking



Regenerative braking is a concept whereby kinetic energ
y

is transformed into some other
useful form of energy. An aircraft generally will generally only brake while on the ground
after landing, therefore, the most appropriate form of regenerative braking would be
attached to the wheels of the aircraft, in the
style of a Prius type system. Electric
generators attached to the axles of the wheels would convert the kinetic energy into
electrical energy through the electromotive force of the generator.

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5.2.12


Gravity powered aircraft


The idea of a gravity powered aircraft was generated from
Robert D. Hunt, a theoretical
physicist and inventor. It operates
on

principles of buoyancy, aerodynamic lift, and gravity.

Basically it consists of large
zeppelin
-
like gas bags which are filled wi
th helium from
storage tanks that are place on
-
board the aircraft. This generates the required buoyancy
for the aircraft to become lighter than air. Compressed
air jets

on the sides of the aircraft
add further
propulsion

to generate thrust. After aircraft
ascends
to the

altitude limit
where it is no longer lighter than the air, some of the stored compressed air
is expanded

into the dirigible areas, decreasing the buoyancy effect of the helium and starting the
aircraft's descent phase. During descent, wind t
urbines mounted on top of the aircraft,
drive air pumps which can refill the on
-
board compressed air storage

[
12
]
.



Figure
18
: The Gravity
-
Powered Aircraft

[
12
][
13
]

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30

FINAL REPORT

6.

Concept
Screening

and Scoring

After coming up with several
concepts the next stage would be concept screening.
Concept screening is frequently an iterative process and may not produce a dominan
t
concept immediately

[
1
]
.
There are several methods f
or concept screening

[
1
]
:



External decision



Product champion



Intuit
ion



Multi

voting



Pros and cons



Prototype and test



Decision
metrics


We div
ided this phase into three

stages
:

Preliminary Concept screening
:

a quick, approximate evaluation aimed at producing a few
viable alternatives

Concept
Scoring:
a more detailed, quantitative evaluation of the concepts

Further concept screening
:

a more careful analysis and finer quantitative evaluation of
the remaining concepts

carried out after concept scoring

Throughout the screening and scoring process, several

iterations may be performed, with
new alternatives arising from the combination of the features of several concepts.

6.1

Preliminary Concept Screening

In the preliminary concept screening we tried to narrow down the concepts based on pros
and cons, multi
voting
,

intuition.

Table

12

shows

the concept screening table carried out
in this step.

Some of the concepts do not conform
to

our mission statement or
fall

far out
of the customer needs criteria, and can be eliminated in a preliminary screening without
t
he need for a concept scoring process. Each group member was assigned t
o do a
comprehensive research on

one or two concepts and present the pros and cons regarding
that concept. After a brainstorming session we eliminated a number of the concepts.
Since e
ach person was researc
hing one or two concept
, which
was

basically different from
the rest of the group, there were chances that personal bias would affect the results. After
recognizing this flaw we decided to do a thorough research by all the group membe
rs, on
the concepts which were recognized to need further analysis. One of the common
mistakes is to eliminate a concept without enough evidence, in an early stage. To bypass
this problem we decided to keep some of the d
oubtful

concepts that might have bee
n
eliminated otherwise.




ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

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FINAL REPORT


Table
12

Concept Screening
Table





Conventional
Internal
Combustion
engine

Solar
Powered
and Solar
Powered
with
Battery
Assistance

Jet
engine

Internal
combustion
engine
(diesel)

Fuel Cell
Powered
with
Battery
Assisted
Takeoff

Hybrid Drive
(Prius
Technology)

Battery
Powered
Electric
Motor
Aircraft

Human

Powered

Aircraft

Wind
Powered

Aircraft

Nuclear
Powered

Aircraft

Regenerative

Braking

Selection
Criteria

Economical
to buy

0

-

-

+

-

-

0

+

+

-

-

Maximize
Power to
weight

0

-

+

+

-

-

-

-

-

-

-

Economica
l
to run

0

+

-

0

+

+

+

+

+

-

+

Suitable to
structure of
the aircraft

0

-

-

0

+

-

+

+

-

-

-

Minimizes

the noise

0

+

-

-

+

0

+

+

+

-

-

Energy
source
Efficiency

0

+

-

+

+

+

+

-

-

-

-

Ecologica
l
sustainability

0

+

-

-

+

+

+

+

+

-

+

Net Score

0

0

-
4

1

3

0

4

3

1

-
5

-
3

Rank

4

4

6

3

2

4

1

2

3

7

5

Continue

Y

Y

Y

Y

Y

Y

Y

N

N

N

N

ENGN 8100
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FINAL REPORT

In the following section we present
the concepts which w
ere eliminated thorough
p
reliminary concepts screening

phase
. As mentioned earlier, the elimination was basically
based

on pros and cons, multi vot
ing,
intuition

and concept screening table.



Human Powered Aircraft

Since the customer needs was initially generated from the 5 groups (whole class)
,

we had
a talk with all the groups about this concept and there was consensus not to include
human powered aircraft due to low power to weight ratio and not s
atisfying the “ease of
use” need
(Recreational aircraft mission statement)
.



Wind Powered Aircraft

T
his concept could not pass our initial screening since it couldn’t provide enough power to
weight ratio to generate thrust even in its most ideal setting. The only possible use we
could find was as an emergency source of energy for powering the internal
devices in the
aircraft in case
the
main internal power source faces

a problem
.



Nuclear Powered Aircraft

Basically, the cost and weight of a nuclear reactor aircraft would be a lot higher than our
specification constraints.



Regenerative Braking

Regenerative braking was suggested as a concept for regaining energy on landing the
aircraft. Given the amount of time spent on the ground compared to in the air, this
concept was rejected. The perceived benefits of regenerative braking were insignificant
compared to the amount of additional weight and engineering effort required.



Gravity Powered Aircraft

Gravity powered aircraft is still a concept and hasn’t proven to be practically viable.
Nevertheless, it requires huge zeppelin like gas bags and cannot

satisfy ultralight aircraft
size constraints.

6.2

Concept
Scoring

Before further concept screening, concept scoring was carried out based on a selection
criteria
. In the “customer needs” section we ended up ranking the customer needs. For
concept
s
creening w
e use a

subset of those needs. We selected
7
of the needs that
scored
the highest and were also measurable
.

Table 1
3

shows the result of the scoring process.
The ratings are based on the information and data which were presented in the
benchmarking and
concept gene
ration section and group member

s

intuition of the
concepts.


ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

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33

FINAL REPORT




Conventional internal
combustion engine

Solar Powered and Solar
Powered with Battery
Assistance

Jet engine

Internal combustion engine
(diesel)

Fuel Cell Powered with
Battery Assis
ted Takeoff

Hybrid Drive (Prius
Technology)

Battery Powered aircraft



Weight

Rating

Weighted
score

Rating

Weighted
score

Rating

Weighted
score

Rating

Weighted
score

Rating

Weighted
score

Rating

Weighted
score

Rating

Weighted
score

Economical to
buy

0.2

3

0.6

1

0.2

2

0.4

3

0.6

1

0.2

2

0.4

3

0.6

Maximize
Power to
weight

0.15

4

0.6

2

0.3

5

0.75

4

0.6

2

0.3

4

0.6

2

0.3

Economical

to run


0.15

2

0.3

4

0.6

2

0.3

3

0.45

4

0.6

3

0.45

4

0.6

Suitable to
structure of the
aircraft

0.1

3

0.3

3

0.3

3

0.3

2

0.2

2

0.2

1

0.1

5

0.5

Minimizes the
noise

0.1

2

0.2

4

0.4

1

0.1

2

0.2

4

0.4

2

0.2

4

0.4

Energy source
Efficiency

0.05

3

0.15

4

0.2

2

0.1

2

0.1

2

0.1

3

0.15

2

0.1

Ecological
sustainability

0.25

2

0.5

5

1.25

2

0.5

2

0.5

4

1

3

0.75

4

1

Total Score

1

2.65

3.25

2.45

2.65

2.8

2.65

3.5

Rank


4

2

5

4

3

4

1

Table
13

Selection Criteria for Energy Conversion System Selection

6.3

Further concept screening

As mentioned

earlier, concept screening is an iterative process. Based on the concept
scoring
,

Solar and Fuel cell concepts scored among the highest. However in this stage we
decided to eliminate these two concepts mainly because they could not satisfy our budget
cons
traints.

Moreover,

Jet engine concept scored t
he lowest and was eliminated at this
point of time
.

6.3.1

Solar Powered
and Fuel Cell power Elimination:

Table 1
4

shows some specifications for

existing solar powered aircrafts.
As you can see,
t
he cost NASA’s Helios

with a 30
kW

solar array output
,

was about 9.7 m AUD.



Price

Solar array
output

Wing Span

Motor
power

Weight

Allowed
Mass

Helios

9.7 m
AUD

30
kW

75.28

21
kW

600 kg

330kg

Pathfinder

-

8
kW

35

-

270 kg

-

Sunseek
e
r

-

-

17.5

5.98

91kg

-

Table
14

Existing Solar Powered Aircraft Specifications

[
14
][
15
]


From
T
able 14

and
[
16
]

we came up with
Table 15

which

is a comparison for investment
of equipment to generate 1
kW

for 5 energy sources.

ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

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34

FINAL REPORT


Energy Source

Investment of
equipment to
generate 1
kW

Lifespan of
equipment
before major
overhaul or
replacement

Solar

200 AUD/Watt


20years


Fuel Cell

3000 AUD

2000h

Lithium Polymer
battery

1500 AUD

1500h

Gasoline

30
-
100 AUD

4000h

Diesel

40
-
100 AUD

5000h

Table
15

Cost Comparison of 5 different energy sources to generate one
kW

of energy

Based on the
T
ables 14 and 15
it

is obvious that the cost of
the
solar

concept

falls out of
our budget by a high margin. Producing 1
kW

of solar
power (using
high efficiency solar
cells
)

will require (1000 * 209 = 209,000 AUD) investment in equipment.

On the other hand
,
f
uel cells cost twice as much as batteries. Considering the fact that fuel
cells would require auxiliary equipment such as hydroge
n tank
s
,

which

makes them to
weigh

much

more than
batteries and fuel cells are usually used in a combination with
batteries,

the finished price of fuel cell

concept
will be even more t
han twice of the
batteries. Therefore
we calculated that
the cost of fu
e
l cell powered aircraft falls out of
our budget limit
.

6.3.2

Jet Engine

Elimination

As
in
the
solar powered and f
uel
c
ells concept
s
, the main drawback of this option is the
cost.

(This concept also ranked the lowest in concept scoring section)

As expressed in
Ta
ble
6
, the cost of buying and running this type of engine is extremely
high.



Buying cost: AUD$50,000



Running cost: AUD$32,000 (1 year, 4 hours a week, consumption of
178.4 Litres/hr

and a fuel price of
$0.889/Litre
)

Clearly, this is out of our budget and
target market, for this reason this option is also
discarded.

7.

Concept selection and

Justification

After the analysis of the last chapter (concept screening), we

are

left with mainly two
options: Internal Combustion
Engine

(
gasoline/diesel/hybrid)

and
Battery
P
owered
ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

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FINAL REPORT

A
ircraft with
Electric Motor. In this chapter we will analyse these concepts and mak
e a
recommendation based on our findings
.

W
e have done an analysis of cost
vs.

power and cost vs. power/weight ratio for existing
internal combustion engine
s and electric motors.
D
ata sets
in
Table 16

and

17
s
how the
results of the analysis.
Figure 19

and
20

are a graphical representation of the data sets for
a better understanding.



Internal Combustion Engine

Model/Brand

Power
(HP)

Cost
(AUD
)

Weight
(Kg)

Fuel Weight(Kg)

Power/Weight

Rotax 582

65

7951

36

15

1.275

Rotax 503 single Carb

46.5

5916

37.4

17

0.855

Rotax 503 dual Carb

50

6070

38.3

20

0.858

Rotax 447

39.6

5105

32.6

22

0.725

Rotal 912 UL

81

16077

55.4

25

1.007

Rotal 912 ULS

100

18389

56.6

30

1.155

Rotax 914 UL

115

26827

70

35

1.095

Table
16
: C
ost vs. power
Data Set for Internal Combustion Engine


Electric Engine

Model/Brand

Power (HP)

Cost
(AUD
)

Weight

Battery Weight

Power/Weight

ElectraFlyer

18

3785

11

35

0.391

PMG132 72v

10.108

2039

24.8

19.5

0.228

PMG080 24v

2.24

805

7.5

4.3

0.190

LM202 60v

57

6000

20

110

0.438

Table
17
: Cost vs. power

Data Set Electric Motor

ENGN 8100
:

INTRODUCTION TO SYSTEMS ENGINEERING

Page
36

FINAL REPORT


Figure
19
: Cost
vs.

Power comparison, Internal Combustion Engine and Electric motor


Figure
20
: Cost
vs.

Power/Weight comparison, Internal Combustion Engine and Electric motor


As you can see
,

i
t
is very difficult to directly compare an internal
combustion engin
e with
an electric motor

based on the above charts since both cost and power/weight ratio for