University of California, Irvine – UCI Team Caddyshack

The UCI AIAA student chapter participates in the annual AIAA Design
Build Fly (DBF) competition.

This competition gives the engineering students a chance to apply
classroom knowledge, gain hands on skills, and experience an
industry level project-development from conceptual design to
building and testing an optimized final product.

Over the past 6 years this project has grown substantially in size and
skill with the help of previous DBF students, currently working in the
aerospace industry, who meeting with the current team weekly.

Introduction

Team Organization

2011 Competition

Conceptual Design

Preliminary Design

Detailed Design

Manufacturing

Testing

Expected Final Performance
Project Manager
Kamil Samaaan
Report
CAD
Lead: Giuseppe
Venneri
Lead: Patrick
Lavaveshkul
Patrick Lavaveshkul
Semir Said
Westly Wu
Byron Frenkiel
Kerchia Chen
Sothea Sok
Angela Grayr
Erica Wang
Test Flight
Coordinator
Alexander Mercado
Public Relations
Chen Weng
Chief Engineer
Giuseppe Venneri
Aerodynamics
Propulsion
Structures
Payload
Lead: Curtis Beard
Lead: Kevin Anglim
Lead: Hiro
Nakajima
Lead: Jacqueline
Thomas
Lead: David Martin
Kurt Fortunato
Gagon Singh
Kevin Koesno
Michael Gamboa
Semir Said
Westly Wu
James Lewis
Giuseppe Venneri
Rayomand Gundevia
Thuyhang Nguyen
Anthony Jordan
Max Daly
Kasra Kakavand
Khizar Karwa
Alexander Mercado
Yi-lin Hsu
Stability and
Control

Aerodynamics: Computes flight characteristics and necessary wing
dimensions.

Propulsion: Analyzes propulsion system to find best motor, propeller and
battery combination.

Structures: Optimizes load-bearing components and maintains a weights
build-up of the aircraft.

Payload: Designs and manufactures steel payload and restraints for the
payload and aircraft.

Stability & Control: Ensures aircraft meets S&C standards and
closely with aerodynamics to predict flight performance.
works

Competition consists of 3 missions:
◦ Mission 1: Complete as many laps as possible in a 4-minutes. time
frame (M1 = Nlaps/Nmax)
◦ Mission 2: 3 laps with a steel bar payload.
(M2 = 3x(Payload weight/Flight weight))
◦ Mission 3: 3 laps with
a team-selected
quantity of golf balls.
(M3 = 2x(Nballs/Nmax))

Constraints for 2011:
◦ Battery weight: ¾ lb
◦ 20 amp slow-blow fuse
◦ Aircraft must fit in a commercially-available carry-on suitcase.
◦ L + W + H = 45 inches (no dimension can exceed 22 in.)
◦ Suitcase must include entire flight system, including aircraft, battery and
all required parts and tools.
◦ Golf balls are regulation sized and the steel bar payload dimensions are
constrained: 3 in. width x 4 in. length minimum.
◦ Aircraft must be hand-launched.

Sensitivity Analysis

Configuration Figures of Merit
◦ Aircraft Configuration

Subsystems Selection
◦ Motor Position
◦ Landing Methods
◦ Yaw Control
◦ Wing Attachment Methods
◦ Payload Configuration

Final Configuration

The objective of this analysis is to identify the mission parameters
that have the largest impact on the score.

A maximum of 64 golf balls and 9 laps were the benchmark values,
determined using the data from past DBF competitions.

Thrust and drag models were used in a simulation program to design
hundreds of planes and perform this analysis.

Mission 1 favors a small plane and
payload with a large propulsion
system.

Missions 2 and 3 favor a large
plane with a high wing loading.

In order to select an aircraft configuration, a scoring system
based on figures of merit was produced. Each was weighted
based on results of the scoring analysis:
◦ System weight (35%)
◦ L/D (20%)
◦ Cargo space (15%)
◦ Maneuverability (10%)
◦ Manufacturing (10%)
◦ Hand launch (10%)
Aircraft Configuration
Mono Plane- (Conventional)
•Relatively
easiest to design and build. Known
comparative values for performance.
•Relatively
heavy configuration not optimized for
specific competition.
Flying Wing
•Efficient
use of space. Lack of unnecessary
FOM
Conventional
Flying Wing
Delta Wing
Biplane
0
2
1
-1
20
0
1
0
-1
Cargo Space
15
0
0
1
0
Stability
10
0
-2
-1
1
Manufacturability
10
0
-1
-1
-1
more complex to design and manufacture.
Hand Launch
10
0
-1
0
-1
Biplane
Total
100
0
50
30
-65
elements decreases weight. High L/D
•Significantly
less stable and more difficult to
manufacture.
Delta Wing
•Fly
at high angle of attack. Allow additional cargo
placed in wing.
•More
unstable than a conventional and somewhat
•Slightly
•Much
more stable and higher structural strength.
Weight
Aircraft
System Weight
35
L/D
Final Decision: Flying Wing
heavier and unnecessary additional
elements.
Would be able to hold a maximum amount of cargo
using the lifting surface as the payload bay without a
significant drag penalty.

Tractor- Lightweight, higher efficiency and
Single
Single
Double
Weight
Tractor
Pusher
Tractor
System Weight
45
0
0
-1
-1
Drag
20
0
1
-1
0
Hand Launch
15
0
-2
1
-2
Stability
10
0
-1
0
-1
Cargo Space
10
0
1
2
-1
Total
100
0
-10
-30
-95
less dangerous hand launch.

Push-Pull
Pusher- greater lift due to lack of propwash, limits the maximum amount of
sweep and a dangerous hand launch.

FOM
Double Tractor- Smaller propellers,
increased cargo space in center, less
dangerous hand launch, increased weight
and difficulty in locating the CG.

Push-Pull- Increased weight, limits
maximum sweep and provides a more
dangerous hand launch.

Belly Landing- Low weight, low drag,
would be difficult to hand launch and
vulnerable to fatigue.

Skid/ Handle- Improved hand launch,
increased structural support, potential
FOM
Wt
Belly
Landing
Handle/ Skid
Skid and
Piano wire
additional storage space and slight
Tricycle
increase in weight and drag.
Skid & Wire- Decreased stopping
System Weight
45
0
-1
-1
-2
Drag
20
0
0
-1
-2
distance, minor increase in weight and
Hand Launch
15
0
2
-1
-2
increase in drag.
Stability
10
0
0
1
2
Cargo Space
10
0
2
0
0
Total
100
0
5
-70
-140


Tricycle- Reliable and high strength,
however significant increase in weight,
drag and difficulty of hand launch.

Winglets- Reduced drag, light
weight and provides yaw stability.

Wingtip rudders- Increased pilot
control and increased weight.

Aft Vertical tail-Greater moment to
Wingtip
Aft Vertical
Split
Rudders
Tail
Flaps
0
-1
-2
-1
25
0
0
-1
0
Hand Launch
15
0
0
-1
0
Stability
15
0
1
2
0
Total
100
0
-30
-100
-45
Weight
Winglets
45
Drag
correct yaw and significant
increase in weight.
FOM
System
Weight

Split Flaps- Provides only a minor
increase in weight, complex and
difficult to implement correctly and
cause and increase in drag.

Fully enclosed internal payload compartment- Less drag and a
lower weight. Requires a larger t/c airfoil or a larger aircraft.

Fuselage (BWB) style compartment- More efficient method of
cargo placement near the Center of Gravity, increased drag and
difficulty to manufacture.

Design and Optimization Programs

Design Methodology
◦ Mean Aerodynamic Chord

Mission Model
◦ Winglets

Aerodynamics
◦ Airfoil Selection
◦ Wing Sizing

Propulsion Sizing

Drag

Lift

Stability and Control





SolidWorks: used to model aircraft prototypes and to help determine
airfoil selection
XFOIL: Used to analyze possible airfoil choices for aerodynamic
characteristics
Microsoft Excel: Used extensively for data analysis, storage and
graphing
AVL: Used for flight-dynamic analysis and to ensure overall stability
of the aircraft
MATLAB: Used to create an optimization program

The Aerodynamics team planned and organized the design process into
several design steps outlined in the flowing diagram.

A conceptual design is produced using the sensitivity analysis results.

A preliminary design is developed using the conceptual design results and
initial estimates.

An optimization program is developed in Matlab to model the performance
of a design for all of the missions.

Several iterations of optimizing, building and testing are done to produce a
high performance aircraft.

The mission profile was modeled using for loops and while loops in
MATLAB.

The aerodynamic and propulsion forces were computed for every loopiteration to determine the change in position and velocity of the aircraft
during that period of time.

The program assumed some initial conditions for takeoff such as hand
launch velocity and wind conditions.

The mission model program computes:
◦ the energy used
◦
the number of laps completed in 4 minutes
◦ The maximum payload capacity a design could carry.

The total flight score is computed for several designs which resulted in
an optimized design.

The majority of airfoils that were considered were the reflex type for our flying wing.

Studies were done using XFOIL and SolidWorks to determine which airfoil best suited
our needs.
Coefficient of moment vs. angle of attack
NACA 4-digit symmetric series study

Wing loading was optimized
based on the total flight score
using our mission profile MATLAB
program.

The figure to the right shows a
plot of the total drag as a function
of the aspect ratio for mission
three during takeoff.
Name
Battery Selection


Weight
oz
Kv
RP
M/V
Max
Current
Amp
Power
W
Resist
ance
Ω

Considered several different
battery types and the
Hacker
A30-14L
capacity-to-weight ratios.
Hacker
A30-12L
A mission profile was used to
determine an estimate of the
amount of energy needed to
Propeller Selection
performs better at high
4.6
800
35
490
0.038
4.6
100
0
32
400
0.041
4.8
118
5
35
450
0.023
5.5
110
0
35
600
0.015
Hacker
A30-10L
Hacker
A30-8XL
speeds while low pitch
performs better at low
speeds.

Capacity mAh
Diameter- Larger
diameter= more thrust
and more power
complete each of the
Battery
missions.
Pitch-High pitch
required from motor.
Ah / oz
Motor Selection
o
Redicom
500
1.56
700
1.75
1500
1.92
1700
1.7
2000
1.72
2200
1.44
3300
1.71
Nimh
Elite 1500

Elite 1700
Elite 2000
Elite 2200
Elite 3300
small diameter.
Based on the battery and
the current limitation of
20A, the maximum power
the battery could supply to
the motor is 300 W.
Mission 1: High pitch
o
Missions 2 & 3: Lower
pitch and larger
diameter.

The drag was computed using the equivalent flat plate area method.

The wing was optimized
for the cruise of mission
two and three.

Washout helped focus
the peak of the CL
distribution.

We calculated our MAC and
simulated our aircraft’s geometry
through AVL

The figure to the right shows the
resulting pole-zero map of the
eigenvalues calculated by the
program.
WINGLETS

An eignemode analysis made in AVL
showed that the flying wing was susceptible
to low Dutch roll damping.

Dutch roll was clearly visible during test
flights, but Pilot still maintained good control.

Sized for Dutch roll damping above 0.02.
Optimized Winglet Dimensions
Height c/4:
9.5 in
Sweep:
37 degrees
Distance behind LE:
6.0 in
Taper ratio:
0.7

We modeled the wing spar
as an I-beam.

Carbon strips were laid on
the top and bottom of the
wing with a 5/8” diameter
carbon rod running between
the strips to create our spar.

Testing later on showed that
the wing with two spars was
favored over the single spar.

In an effort to reduce weight, the motor mount, landing skids and launch
handle were combined into one carbon fiber structure that was
integrated into the center wing section.

This design proved to be very efficient in cargo space utilization.

The forward end is used as an electronics compartment to house the
speed controller and the fuse.

The skid and handle section was designed as a channel that was sized to
fit the propulsion battery pack.

We used molding methods investigated over summer to create our
center section.

A male and female mold were created using SolidWorks template
printouts and hotwire cut foam.

Foam wings were
created and hollowed
out using wooden
templates and a hotwire
as investigated over
summer.

Wings were then coated
with fiber glass and a
strip of carbon fiber for
strength.

Wingtip Testing

Propulsion Testing

Handle Design Tests

Flight Tests

Wing tip testing was used to confirm and validate wing-spar
calculations and our hollow core foam design.

Testing was performed
by securing the tips
of a wing and loading
it mid-span until
failure occurred.

Static thrust testing was conducted to measure the performance of various
propulsion systems.

Dynamic thrust testing was conducted using a load cell that was mounted to a
custom-designed sliding motor mount and was used to collect dynamic thrust
data during flight.

This data was used to accurately model the dynamic thrust in the mission profile
optimization program.

Fuse and battery testing were also conducted in the lab to determine the limits
and range of operation.

Different handle designs were
created and tested initially to
find which best suited the hand
launcher to give him control
and stability at take off.
Prototype I
The following are a combination of both
prototypes, and were used to calibrate the
preliminary design.
Takeoff speed:
30 ft/s
Max wing loading:
28 oz
Locating CG for stable flight: 15% static
margin
Dutch roll damping:
Lap time:
Controllable
37 s
Prototype II

Prototype I
◦ Provided insight into launch and landing techniques.
◦ Provided data for the calibration of the wing loading.

Prototype II
◦ Improved stability.
◦ Increased payload space.


Maximum of 4 flight attempts allowed
Mission One:
◦ 1st flight attempt: 6 laps in 4 minutes
 Late in the day

Mission Two:
◦ 2nd flight attempt: fuse blew within seconds after hand
launch
 Noon, +90°F, No wind
◦ 3rd flight attempt: ran out of battery with one more turn left
in the course
 Late in the day
 Very spectacular flight
◦ 4th flight attempt: Propulsion strategy gone amiss
 Noon,
 Even with a reduced payload, our plan to increase thrust on the
downwind blew the fuse.



The conditions surrounding the fuse in
Tucson are very different than those in Irvine.
The fuse will blow at a lower current in
Tucson.
Flying later in the day helped with the above
handicap, when it was cooler. In fact, heavy
planes like those from Israel and MIT skipped
their noon rotation and waited till the late
afternoon to fly their airplanes (9 lbs!!).
Conduct propulsion tests and test flights with
competition weather conditions in mind.