2007-2008 RIT MAV Mid-Term Review Michael Reeder – Team Leader Kevin Hand – Lead Engineer Todd Fernandez - ME Susan Bieck – ME Jeremy Teets – ME Cody Rorick – ME Adam Bosen – CE …where the sky is only the beginning… …and the ground is likely the end…
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2007-2008 RIT MAV Mid-Term Review Michael Reeder – Team Leader Kevin Hand – Lead Engineer Todd Fernandez - ME Susan Bieck – ME Jeremy Teets – ME Cody Rorick.
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2007-2008 RIT MAVMid-Term Review
Michael Reeder – Team LeaderKevin Hand – Lead EngineerTodd Fernandez - MESusan Bieck – MEJeremy Teets – MECody Rorick – MEAdam Bosen – CE
…where the sky is only the beginning……and the ground is likely the end…
Put a face to the name…
Mike ReederKevin Hand
Sue Bieck
Jeremy Teets
Adam Bosen
Todd Fernandez
Cody Rorick
Presentation Overview
Organizational Structure Overview of past MAV Projects Introduction/Objective of 2007-2008 RIT MAV Senior Design I deliverables Concept generation Preliminary analysis Platform design and structures analysis Propulsion system selection Airfoil selection MAV control system Design of experiments Indication of progress on deliverable completion
Organizational Structure
Mike Reeder-Team Leader
Kevin Hand-Lead Engineer:
Design of Experiments,
Systems Integration
Todd Fernandez-Propulsion and
Composites
Sue Bieck - Airfoil Analysis
and Aero Structures
Jeremy Teets -CAD Generation
and Aero Structures
Cody Rorick - Flight Dynamics and Component
Integration
Adam Bosen -Component
Integration and Operating Software
Overview of Past MAV Projects
Objectives: Fly 600 m Capture an image Obtain a reliability of 80%
Project went through 5 phases Phase 1: Previous year’s MAV
Firefly motor 300 mA-h battery 6” prop
Phase 2: New Propulsion System 3 x 2” prop Feigao Motor produced more thrust
Phase 3: Angle of Attack (α) Phase 4: Limiting Control Surfaces
Control surfaces determined to be a source of failure
Enabled turning but with limited success
Phase 5: Rudder Design (stiff wing) Throttle use mimics elevator Controlled turning in yaw reduced pilot error 6.5” platform (longest linear dimension)
Phase 5 ResultsBattery, α Flight Time (seconds) Repeatability
Primary Objective: Create a Micro Aerial Vehicle, expandable in nature for future
RIT research, that is simple, robust and stable in design and is capable of reading back information regarding the vehicle’s speed, angle of attack, pitch, yaw and roll rates. Flight Dynamics competition (held internationally) establishes target specifications (engineering metrics) Max linear dimension is 80 cm Max weight is 1 kg Required flight time is 4 minutes
Secondary Objective: Compete in international Flight Dynamics competition
Introduction/Objectives of 2007-2008 RIT MAV
Previous MAVs have been designed around control by an operator with a RC controller on the ground
Control systems are essential to achieving fully autonomous flight
The 2007-2008 RIT MAV will be at a level of development between being fully remote controlled and semi-autonomous with the introduction of control systems being the next step in the development process
Fully Remote Controlled
Introduction of ControlSystems
Fully Autonomous Flight Achieved
2007-2008 RIT MAV autonomous
autonomous
Flight Information
Microcontroller Tri-axial accelerometers
Differential pressure sensors (AOA, velocity)
How do we achieve… …simplicity?
The best airfoil for the application is chosen Fuselage/pod designed around component sizes
…robustness? Foam wrapped in carbon fiber and fiberglass achieves robustness Components used to be placed inside of fuselage/pod for protection
…stability? Minimizing size of platform no longer a concern; therefore, design plane having
a large wingspan with the use of winglets to improve lift Use of recommended aspect ratio in conjunction with rear rudder, ailerons and
elevators supported by “basic” flight dynamic calculations …expandability?
Use of large platform allows for future optimization Microcontroller increases capabilities for future research (see following slides)
Break down of MAV into subfunctions
MAV platform consists of Airfoil and aero structures design
Propulsion system Motor selection Prop selection Battery selection
Components/electronics Component selection Design of experiments Preliminary component testing Systems integration
Breakdown of MAV into subfunctions
Semi-autonomous
flight
Flight Information
Microcontroller Tri-axial accelerometers
Differential pressure sensors (AOA, velocity)
Controls
Base station (laptop
configuration)RC controller GPS (future)
Senior Design I Deliverables
Platform design decided upon Engineering metrics/product specifications completed List of components and materials compiled 3-D CAD model of plane created (XFOIL, Pro-E, etc.) Foam model built based on concept generations Experiments designed to test components’ proper functionality Components ordered/in team’s possession Components in possession are in test process Foam plane is built and glide tested
Concept Generation
Started with brainstorming sessions to create various platform and propulsion ideas
Use of Pugh matrices and +, 0, - technique to narrow down spectrum of choices
Team members generated concept drawings/models on their own to emulate narrowed down choices for purposes of visualizing different platforms
KRl = Correction factor. Sfs = Projected side area of the fuselage.
lf = Length of Fuselage. d = Maximum fuselage depth
Zw = Distance parallel to the z-axis, from wing root quarter chord to fuselage centerline.
= Coefficient of lift with respect to alpha of the horizontal tail.
0n
C
wwLvffsRlnW ARdzCSlSkkSbV
,,,,,,,,,,
VLC
Preliminary Analysis:Lateral Stability
Setting and solving for lH you arrive at:
lH = f( )
Where bH = Wing Span.
= Coefficient of lift with respect to beta of the horizontal tail.
= Coefficient of lift with respect to beta of the vertical tail.
= Coefficient of roll with respect to beta of the wing & body.
wbVHlwwLLVwHH CdzARCCSSSb
,,,,,,,,,
HLC
wblC
lC
0l
C
Platform Design
Platform Design
Initial structural choices were between a Flying wing and a conventional airframe
Due to requirements of the project, a conventional airframe was chosen (see Pugh matrices)
Wing position was chosen to be a top wing configuration for flight stability
With the deciding factor of propulsion being made, additional concept drawings were created
Two designs were generated: a simple design with a tube as a fuselage and another with a tube and blended wing portions
The blending of the wing was done to reduce turbulence effects at the wing-fuselage intersection
Platform Design: Additional Sketches
Platform Design:Prototype 1 – Pro-E Generated
20 inch fuselage 3 inch diameter on the fuselage at largest point 29 ½ inch wingspan Span on horizontal tail is 8 inches Symmetrical airfoil on horizontal tail ¼ inch thick Vertical tail is 4 inches tall
Platform Design: Prototype 1 – Pro-E Generated
Structures Analysis
Structures Analysis:Design Constraints
Minimum weight Maximum durability (crash worthiness)
Enable proper flight characteristics Enable mounting of tail Enable control of flight surfaces Enable proper location of H&V tails Minimize detrimental effect of fuselage on wing lift Minimize drag
Provide volume for components Allow Proper location of C.G. Allow adjustment of C.G. location Allow extra volume for future component expansion
Structures Analysis: Wing Structure
12% max thickness wing Total max thickness is 0.9608” (XFOIL
determined) Highly cambered Planned construction Skinned hollow structure also allows
use of internal space Flaperon to be molded as part of wing Wing endplates manufactured
separately to allow internal wing access with removal
Structures Analysis: Fuselage Construction Requirements
Separate composite structure from wing
Supports tail Provide motor mount Light and durable Contain components
Propulsion System Selection
Propulsion System Selection
Create sufficient thrust to enable flight envelope Speed range 0 to ~50mph Thrust : Weight greater than 1:1 at 1kg weight level. (allowing future
platform expansion) >4min battery life at full throttle Reserve battery capacity to support future enhancements of
autonomous capabilities Minimal system weight Minimal system cost Minimum Electrical Noise System Safety
Propulsion System Selection
Determine required propeller characteristics Pitch picked based on max speed desired Propeller diameter picked to maximize efficiency also considering flow over the
fuselage/wing Motor selected to match propeller
Sized as small as possible to minimize weight Motor constant selected to match prop pitch to Vmax
Motor analysis done with concern for motor heating
Motor controller chosen for motor Amax
Battery selected to match system Series cells selected to create >=12V system Battery selected to match single pack to amp/hour requirements Manufacturer/design selected to allow required discharge rate with safety
margin to prevent battery damage
Propulsion System Selection
Single motor Small Brushless DC motor. Peak Watts 120 peak current 11amps Light, closely matches required motor constant (RPM/Volt), high quality components, small frame,
integrated gearbox Inefficient (~58%-67%) in operational envelope. Expensive, requires mount design
Single Prop 12” diameter 8” pitch Large enough to provide flow over wing, flow around fuselage, and flow over control surfaces at low
flight speeds. May be user safety risk, may be reliability/durability issue during landings
Speed Controller 20 Amp max speed controller (12g weight)
Battery 800 mAh/cell. 3.7 V/cell 20 C max discharge rate Provides 11.1 V and 4800 mAh total capacity Provides >8min run at full throttle/max load (vertical acceleration). Provides ~3 hours life at level
cruise (~33% throttle position at Clopt) Easily expandable for future research
Initial metrics used to calculate non-dimensionalized operating conditions Equations
NASG and UIUC airfoil databases searched for any low Reynolds number airfoil listings
XFOIL viscous analysis used to analyze each of 160 possible airfoils discovered in the databases using the operating conditions relating to initial metrics Re=144033, M=.039, a=5° Record airfoil parameters
3 airfoils selected for secondary analysis based on their high Cl and Cl/Cd values Selig S1223 (Best Cl) Eppler E62 (Best efficiency) Selig S1210 (Balance of Cl and Cl/Cd)
Vc
Re aRT
VM
Airfoil Selection: Secondary Analysis
XFOIL utilized to obtain Cl data for the highest lift airfoil (S1223) over a range of AOAs from 0° to just beyond Clmax for 1 mph increments between V=15 mph and V=30 mph
Apply the following equations to find the maximum lift at each velocity (correcting for finite wing)
The maximum lift is found to be too low for our application Second iteration of metrics required to increase lift
c=8 in=0.667 ft Effective span (tip-to-tip span)-(4in): b=25.5 in=2.125 ft
Reynolds number recalculated for new metrics and XFOIL utilized to obtain performance data (Cl, Cd, and Cm) on the three airfoils
Performance data analyzed with respect to lift production and efficiency
Re1
A
CC
Cl
lL
180LL CC cbVCL L
2
2
1
Airfoil Selection: Results
Maximum Corrected Lift Comparison (Assuming a 20% Increase in Lift Due to Winglets)
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
15 17 19 21 23 25 27 29
Velocity (mph)
Lif
t (g
) Selig S1223
Eppler E62
Selig S1210
Airfoil Selection: Results Continued
Re 192044 (V=30 mph)
0
0.5
1
1.5
2
2.5
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09
Cd
Cl
Selig S1223 Eppler E62 Selig S1210
Re 192044 (V=30 mph)
0
0.5
1
1.5
2
2.5
-10 -5 0 5 10 15
(deg)
Cl
Selig S1223 Eppler E62 Selig S1210
Airfoil Selection: Results Continued
Efficiency vs AOA Study Re=192044
0
20
40
60
80
100
120
-10 -5 0 5 10 15
(deg)
Cl/C
d
Selig S1223
Eppler E62
Selig S1210
Airfoil Selection: Corrected Results
Corrected Lift Comparison At Most Efficient AOA for Each Velocity(Assuming a 20% Increase in Lift Due to Winglets)
0
100
200
300
400
500
600
700
800
900
15 17 19 21 23 25 27 29
Velocity (mph)
Lif
t (g
) Selig S1223
Eppler E62
Selig S1210
Airfoil Selection: Final Decisions
Eppler E62 Best efficiency between of about 2° and 5°; however
efficiency drops precipitously beyond these values Very peaky and irregular efficiency, lift, and drag curves.
Narrow range of useable values: will decrease stability and make the plane more difficult to fly controllably Eliminated
Selig S1210 Highest corrected lift when operating at most efficient Moderate corrected Lmax in most likely flight envelope (V>=20
mph) Best efficiency for extreme values, moderate efficiency for
moderate values Smooth and regular efficiency, lift, and drag curves and wide
range of useable values (easier to fly) Selig S1223
Highest Lmax in most likely flight envelope Worst efficiency at moderate values, moderate efficiency at
extreme values Smooth and regular efficiency, lift, and drag curves and widest
range of useable values (easier to fly) Lowest corrected lift when operating at most efficient
Selection : Selig S1210
3rd iteration to metrics (based on airfoil selection)• =6° to 7° (most efficient AOA)• Plane mass: m=500 g (based on desired velocity range)
MAV Control System
MAV Control System: Previous Year’s
transmitter receiver
motors
Servos
4 Maximum
cameratransmitterreceiver
PPM motor control
NTSC video
Manual controller
Laptop with TV tuner
user
MAV Control System: Advantages and Disadvantages
Advantages of previous system: Easy to construct Cheap
Disadvantages of previous system: Limited motor control Very little vehicle data Fully manual control
Size 2" x 1" x 0.9" 4" x 2" x 0.8" 3.47" X 1.58" X 0.75" 2.25" x 1.8" x 0.44"Weight 31 g 34 g 45.3 g 33 g
Company Support No No Yes NoPrice $650 $2,500 $900 $1,500
Design of Experiments
Design of Experiments
Differential pressure sensor used in conjunction with a pitot tube to determine aircraft velocity
One differential pressure sensor on each wing to determine pressure difference which will yield AOA experimentally
Accelerometers placed in nose and tail to determine pitch, roll and yaw of aircraft during flight
Design of Experiments
Test Matrix of each component will be developed by end of Senior Design I
Entire team will define input variables and desired responses
Components will be tested to ensure they are in working order, as well as sending accurate information
Experiments will be carried out by entire team Statistical verification techniques will confirm
experiments are accurate and valid Lead Engineer will be responsible for document
control
Indication of Progress…
Platform design decided upon – COMPLETED Engineering metrics/product specifications – COMPLETED List of components and materials has been compiled – COMPLETED 3D CAD model of plane created (XFOIL has been used to narrow down
spectrum of airfoils, CAD model being generated) Foam model built based on concept generations (small scale model built) Tests are designed so that the components for use on the MAV are accurately
measuring required parameters (being looked into, design of experiments being generated)
Components have been ordered and/or are in the possession of the team (some components are being donated)
Components within possession of team are in the process of being tested via methods designed
Foam plane is fully functional from standpoint of flight and glide testing (scale model has been built)