1. Critical Design Review
Purdue University
AAE 451
Fall 2006
Team FORE
Mark Koch
Ravi Patel
Ki-Bom Kim
Andrew Martin
Tung Tran
Matt Drodofsky
Haris Md Ishak
Matt Lossmann

2. Presentation Overview
Mission Requirements
Aerodynamics
Aspect and Taper Ratio
Wing Selection Analysis
Structures
Landing Gear
Weight Determination
List of Components
Wing Tip Vertical Deflection
Bending Moment Study
Skin and Material
Propulsion
Motor Selection
Battery Selection
High Speed Flight
Propeller Properties
Motor Properties
Endurance Flight
Dynamics & Control
Tail Surface Sizing
Control Surface Sizing
Yaw Rate Control Feedback system
Build Schedule
Flight Test
Static Test
Dynamic Test

3. Mission Requirements High Speed Autonomous Unmanned Aircraft
1 lb payload measuring 2.5x4x3 in
Takeoff and Landing Distance of 120 ft
Minimum Climb Angle 35o
Stall Velocity <= 30 ft/sec
Dutch Roll Damping > 0.8
Budget Cost $250.00

4. 3 View Drawing

5. 3-D Picture

6. Aspect Ratio Minimize Drag (Induced vs. Skin Friction)
Skin Friction Drag
Turbulent Flat Plate Approximation
Induced Drag

7. Aspect Ratio Wing Span = 5.44 ft @ AR = 7 V = 49 ft/s V = 130 ft/s

8. Taper Ratio Best Taper Ratio: 0.45 (delliptical = 0) [Anderson]
Induced Drag
Fourier Coefficients
d Summation
1.27% CDi Increase v. Elliptical Lift Distribution

9. Airfoil Selection Constraints: Required CLmax at Vstall = 30 ft/s.
Reynolds Number ≈ 100,000
Martin Hepperle MH45
Constraints:
Required CLmax at Vstall = 30 ft/s.
Reynolds Number ≈ 100,000
Martin Hepperle MH32
Selig/Donovan SD7032
CLmax required depends on
Wing Loading.
W/S = 1.29 [ lbf/ft2 ]
3-D CLmax = 1.21 [with flaps]
2-D CLmax = 1.09 [without flaps]
Source : UiUC Windtunnel Data

10. Airfoil Selection Coefficient of Drag at Vdash = 130 ft/s:
Profile Coefficient of Drag
From Drag Polar
Coefficient of Induced Drag
Function of Coefficient of Lift
Reynolds Number ≈ 300,000
Martin Hepperle MH45
Martin Hepperle MH32
Selig/Donovan SD7032
Minimum CDi Occurs at the lowest CL:
MH45 has lowest CL at minimum CD
Source : UiUC Windtunnel Data

11. Tail Selection Airfoil Section Chosen to: Horizontal Tail
Have low drag
Manufacturability
Horizontal Tail
NACA 0009
Vertical Tail

12. Wing Analysis MH45 Wing Analysis [Raymer & Brandt]
Conversion between 2-D and 3-D
2-D
Re 100,000
Re 485,000
3-D
Units
5.615
6.2041
4.2574
4.6432
1/rad
0.2055
0.0904
0.1850
0.0841 --
1.121
1.0089
12.36
13.36
deg
1.4
1.2153
8.36 10

13. Flap Analysis 2-D Analysis in XFOIL Convert to 3-D [Raymer]
35o Deflection (0.15c)
Convert to 3-D [Raymer]
flapped area over wing area
angle of hinge line to center line

14. Landing Gear Analysis Assumptions: [Raymer] Tire sizing:
Main Landing Wheels support 90% of weights.
Taildragger aft tires are about a quarter to a third the size of the main tires.
Tire sizing:
Diameter : ft (1.96 in)
Width: 0.075ft (0.9 in)

15. Tip-over Analysis Longitudinal tip-over analysis [Raymer]
Angles between most aft/most forward CG and main landing gear should be between 16 to 25 degrees.
The tail-down angle should be between 10 to 15 degrees
Lateral tip over analysis
Main wheels should be more than 25 degrees laterally from Center of Gravity.

16. Wing Assembly Wing Mount Complete wing assembly with fiberglass cover
Leading Edge
Wing Mount
Complete wing assembly with fiberglass cover

17. Skin Materials Trade Study
Purpose: Compare weight of skin made of different materials
Method: Single cell Thin-walled analysis
Result: Fiber glass has lowest weight
Balsa Wood
Fiber Glass
Units 
Shear Modulus
23600
psi
Density
9.68
117.41
lbm/ft3
Required Skin Thickness
0.0684 ft
Volume
0.2895
0.0068
ft3
Weight
2.8017
0.8037
lbs

18. Skin & Material
GRP (Glass Reinforced plastic) wing covering (fiber glass w/ epoxy)
3oz E Glass
Satin Weave Thickness: “
(Two layer ’’)
Epoxy hardener (205(fast) +206(slow))
Epoxy Resin (105)

19. List of Components Total Weight: 5.0074 lb
material
weight (lb)
internal body
balsawood
0.1444
main wing
foam + fiber glass
1.2750
vertical wing
0.0946
horizontal stabilizer
0.2214
fuselage
foam
0.1935
wing Mount
balsawood + foam
0.0181
nose cap
fiber glass
0.0773
motor (w/ gear box)
0.8000
gyro
0.0400
servo (rudder,elevator,flaperon)
0.3791
receiver
0.0397
speed control
0.1000
battery
0.5000
landing gear
0.1243
payload
1.0000
total
(including battery payload)
5.0074
(excluding battery and payload)
3.5074
Total Weight: lb
(excluding control wires, hinges and glue)

20. CG Determination Center of gravity: Center of gravityX
Center of gravity
Moment of inertia (results from CATIA)
Gx (in)
Gy (in)
Gz (in)
11.83
1.23
Ix (slug*ft2) Iy Iz
Ixy
Ixz
Iyz
0.134
0.313
0.185
-0.005
-1.731e-5
-1.613e-5

21. Bending Moment Study

22. Wing Tip Vertical Deflection
Vertical deflection of wing tip
0.1167ft (1.4in)

23. Catia Model Benefits Visualization Moment of Inertia CG Calculation
Weight Estimation
CNC Manufacturing

24. Battery Selection A123 Racing Lithium Ion batteries 5 cells
70A continuous discharge
2300mAh per cell
3.6 V per cell
70 grams per cell

25. Motor Selection Motor Information AXI 2826/10 Gold line 3-5 lipo cells
Kv RPM/V
Max Continuous – 30A
Max Burst – 42A
Acceptable Props: 10x8-13x10

26. High Speed Mission Propeller Properties 10 in propeller 8 in pitch
High Speed = 130 ft/sec
Propeller Properties
10 in propeller
8 in pitch
Advance Ratio - .73
Propeller Efficiency - .85 Cp Ct
RPM – 12909rpm
Output Power – ft-lbf/sec

27. High Speed Mission Motor Properties Power Out – 525 watts
Input Current – 39.1A
Input Voltage – 14.2V
RPM – 12908rpm
Motor efficiency - .95

28. Endurance Mission
Fly endurance mission at 49ft/s

29. Endurance Mission Propeller Properties 12 in diameter 8 in pitch
Advance Ratio - .67
Propeller Efficiency - .85
Cp - .03 Ct
RPM – 4385rpm
Output Power – 23.2 ft-lbf/sec

30. Endurance Mission Motor Properties Power Out – 36 watts
Input Current – 9.3A
Input Voltage – 4.8V
RPM – 4385rpm
Motor efficiency - .81
51 min flight time

31. Class II Sizing of Tail Area (Horizontal & Vertical Surfaces)
MAC = ft (9.78 in)
CG Range = 0.184MAC – 0.327MAC
CG Location = 0.235MAC
AC Location = MAC
Static Margin = 18%
Static Margin Range = 14 %
Sh = 1.0 ft2
Longitudinal Static Stability
Cmα= rad-1
Usually negative
Sv = 0.4 ft2
Weathercock Stability
Cnβ= rad-1
typically 0.06 to 0.2
Roskam

32. Summary Wing Horizontal Tail Vertical Tail Units AR 7 4 2.3 []
Wing
Horizontal Tail
Vertical Tail
Units AR 7 4
2.3 []
Taper Ratio
0.45
0.72
0.6
Area
4.23 1
0.4
[ft2]
Span
5.44 2
0.9583
[ft]
MAC
0.815
0.5

33. Control Surfaces Historical Data: Cessna Skywagon
Trim Diagram [Roskam]
Horizontal Stabilizer Incidence Angle = -1o
Max Trim Elevator Deflection Angle = -15o
High Speed CL = 0.08
Flaperon 
Span 3 ft
Chord
η_ia
0.35Spanw
 ft
η _oa
0.9Spanw
Elevator 2
0.1
 Rudder
η_v_ir
0.2083Spanv
η_v_or
0.9583Spanv
0.375
Pitch, elevator size
Cmδe=
typically -1 to -2
Yaw and/or roll, rudder size
Cnδr=
typically to -0.12
Roll, flaperon size
Clδa=0.285
typically 0.05 to 0.2

34. Modal Parameters Open Loop
Phugoid mode
Damping Ratio: 0.495
Natural Frequency: rad/sec
Short Period mode
Damping Ratio: 0.934
Natural Frequency: rad/sec
Dutch Roll mode
Damping Ratio:
Natural Frequency: rad/sec
Roll mode
Time Constant: 0.49 sec
Spiral mode
Time Constant: sec
Ogata

35. Dutch Roll Feedback Block Diagram
Nominal Gain: -0.11
Dutch Roll closed loop
Damping Ratio: 0.841
Natural Frequency: 10.9 rad/sec
Aircraft and Servo Transfer Function
Aircraft Transfer Function
Servo Transfer Function

36. Root Locus of Control System
Closed Loop Poles for Yaw Rate feedback to Rudder

37. Build Schedule

38. Flightline Tests Static Test (Purdue Airport)
Rate Gyro Gain setting – Correct Deflection
Transmitter Receiver operation
Control Surface operation
Propulsion operation
Dynamic Test (McAllister Park)
Taxi Run – Landing Gear and Tail Wheel controllability
Rate Gyro Gain setting – Correct Magnitude
First flight: (Yaw feedback control off)
Brief liftoff and land to feel initial handing qualities of aircraft
Second flight:
Sustaining flight with turns to evaluate aircraft stability and control
Third flight:
Go through procedures to set rate gyro gain.
FULL THROTTLE FLIGHT!

39. References
Brandt, Steven. Et al. Introduction to Aeronautics: A Design Perspective
Raymer, D. Aircraft Design: A Conceptual Approach. Forth Edition
Stevens, B., Lewis, F. Aircraft Control and Simulation
Anderson, J. Fundamentals of Aerodynamics
Callister, W. D. Material Science & Engineering 2nd edition
Sun, C. T. Mechanics of Aircraft Structures

40. Questions?