1. AAE 451 Team 3 Final Presentation
Jon Amback
Melissa Doan
Stacie Pedersen
Kevin Badger
Jason Hargraves
Colleen Rainbolt
Greg Davidson
Etan Karni
Lazo Trkulja
April 28, 2005

2. Mission Specifications
8 Minute Endurance
Vstall ≤ 20 fps
Vloiter ≤ 30 fps
Climb ≥ 20
descent ≤ -5.5
Feedback system
Stylish

3. Concept Selection

4. As-Designed Vehicle 3-View
Length
4.21 ft.
Wingspan
4.63 ft.
Wing Area
3.58 ft.2
Takeoff Weight
1.95 lbs.
Discuss features:
Unique blended canard design
Retractable landing gear
LED lighting

5. Style Features Canard pusher configuration Blended wing-body design
Retractable landing gear
LED lighting
Winglets

6. Master Design Code Automates sizing iteration process
Constraint diagram generation
Propeller analysis using Goldstein’s blade-element method
Motor analysis / comparison using Prop ’02 functions and MotoCalc database
Battery capacity computation from mission model
Sizing of Wing, Canard, and Vertical Stabilizer
Weight estimation based on construction techniques and known systems weights; CG computation
Automatic generation of FlatEarth input deck
Single code approach ensures all disciplines “design the same aircraft”
1200+ lines of team code
Also leverages 450+ lines of existing propulsion analysis codes and lines in FlatEarth aeroprediction code

7. Constraint Diagram
As-built

8. Propulsion

9. Selected Propulsion System
Kokam 3 Cell 640mAh Li-Poly Battery Pack
Kokam Super 20 Electronic Speed Controller

10. Selected Propulsion System
Graupner Speed 480 Brushed Motor
0.12 Hp at 11.1 V and 10 Amps
MPJet 4.1:1 Offset Gearbox
APC 11” x 4.7” Slo-Flyer Propeller

11. Aerodynamics

12. Selected Airfoil USNPS – 4 Flat lower surface -- easy to manufacture
Thickness suitable for servos and retractable gear
High Lifting Capabilities - Clmax
Low pitching moment
Low Drag - Cd

13. Aircraft Characteristics
DRAG
-Component buildup method: all exposed area contributes to aircraft skin friction and form drag
-Induced drag
LIFT
-Computed lift curve slope, max. and zero-degree AOA lift coefficients to describe lifting properties
-Wing incidence angles, sweep, body shape accounted

14. Desired Operating Point
Polars
Desired Operating Point
CLmax

15. Flight Controls

16. Location of CG and AC CG AC
SM=19.7% (FlatEarth)
Desired ≥ 15%

17. Stabilizer Sizing with X-Plots
Design Point
Static Margin = 19.7%

18. Control Strategy
Feedback yaw rate to the rudder due to expected deficiency
Increase the damping of dutch roll mode

19. Landing Gear, Structures and Weights

20. Landing Gear Layout Nose gear carries 8% of weight; remainder on mains
Tailstrike at 10.0
20.0 tipback angle
Wingtip strike at 15.7° bank
30.0 overturn angle
1.52 ft. track between main gear
20.0
0.5 ft.
2.15 ft.
10.0

21. Weight Distribution

22. V-n Diagram
Ultimate Load Factor
Mission Load Factor

23. Manufacturing

24. Manufacturing Alterations to original design Increased canard area
Did not include ventral fins
No top for fuselage balsa box
Fuselage outer foam was larger and more elliptical in shape
Nose landing gear retracted aft rather than forward

25. Manufacturing Challenges faced: Experience gained:
Inadequacy of hot-wire method
Inexperience with R/C construction techniques
Many hands working on one object
Experience gained:
CNC fabrication
Construction methods
Systems integration

26. Manufacturing

27. Manufacturing

28. Manufacturing

29. Flight Testing

30. Flight Testing Began on time, but experienced problems
Battery destroyed by short circuit in connector
Speed controller BEC unable to source sufficient current (experienced by multiple teams)
Solution: New flight and avionics battery packs

31. Flight Testing First attempt Solution!
Insufficient canard area to lift nose and rotate
Great roll; no takeoff
Solution!
Field fix – added extra area using available resources

32. Flight Testing Success! Canard able to lift nose Smooth takeoff
Some instability
Underpowered
Belly landing

33. Flight Testing Motor adjustment
Purchased brushless motor for more power
Gearbox did not mesh well with new motor
Obtained another, even more powerful brushless motor from ASL

34. Flight Testing Knowledge obtained from flight tests
Retractable gear would not lock in down position
CG location critical
Wide turns
Underpowered using as-designed motor, partially due to weight growth during construction
More than sufficient lifting capabilities from main wing
Need separate avionics battery

35. Final Aircraft Alterations since first flight test
Added avionics battery
Increased canard and elevator area
Installed more powerful brushless motor
Locked landing gear in down position
Fitted LED lighting
Added stylistic trim lines

36. Final Flight

37. Aircraft Summary Parameter Units As-Designed As-Built Difference
Weight
lbs.
1.95
2.81
43.8%
Wing Area
ft.2
3.58
3.60
0.7%
Canard Area
0.31
1.08
252.3%
Vertical Tail Area
0.63
0.56
-11.2%
Prop Size
---
11 x 4.7
12 x 4.4
CG distance from wing Aero Center
ft.
-0.34
-0.76
126.2%
Aileron Area (ea.)
0.11
0.245
123.7%
Elevator Area
0.08
0.29
280.1%
Rudder Area
0.19
0.23
22.7%

38. Budget and Labor Budget Labor Team: spent $177.68 of $150 permitted
Purdue: $149.86, excluding R/C gear
Cost overrun primarily due to cost of balsa purchased locally vs. ordered
Labor
Team worked hours (58 work weeks)
Total labor cost is $117,500 at $50/hr/person

39. Lessons Learned
Order balsa, rather than purchase locally to save substantially on cost
FlatEarth does not predict the aerodynamic center well for non-traditional configurations
Include a large weight margin in design to allow for creep during construction
Include a propulsion power margin commensurate with the weight margin
Robust attachment points are difficult to design and build, especially for landing gear. Take time to ensure joints are sturdy and straight.
Damage tolerance is essential, as the aircraft will crash several times during flight test
Plan to use a separate avionics battery
Consult with Sean and other experienced modelers (e.g. R/C club members) prior to ordering parts, especially avionics and propulsion system
Keep It Simple, Stupid! (KISS)

40. Questions?

41. Backup charts Propulsion Aerodynamics Dynamics and Controls Structures
Economics and Fabrication Plan

42. Graupner Speed 480 Rated horsepower 0.1182 hp @ take-off
Motor efficiency
71%
Motor constants
Kv = 2450 RPM/V
Kt = In-oz/amp
R = Ohms
Io = 1.09 Amps
Rated number of cells
3 Lithium
Rated Amps
10 Amps
Rated voltage
8.4 V
Weight
0.221 lbs
Price
$25.90 (Hobby Lobby)

43. Selected Gearbox Gear Ratio (available) 4.1:1 Efficiency 87% Price
$13.90 (Hobby Lobby)

44. Selected Propeller Properties
Prop (Calculated)
11 in. x 4.4 in
Prop (Available)
11 in x 4.7 in
RPM
5000 RPM
Weight
0.113 lbs
Chord
0.6 in.
Airfoil of Propeller
Clark-Y
Price
$3.09
Reynolds Number
~100,000

45. Other Propeller Options
Pitch and Diameter
APC Slow-Flyer
10 x 7
10 x 4.7
11 x 6
11 x 7

46. Battery Properties Kokam 3-Cell 640 mAh Continuous Amps 9.6 A
Nominal Output
11.1 V
Weight
0.119 lbs
Price
$31.99

47. Speed Controller Kokam Super 20 Amp Auto low voltage cutoff (lvc)
Continuous Amps Output
20A
Peak output current
200A
Input operating voltage
2.1 to 18V DC
Weight
lbs
Price
$33.99

48. Graupner Speed 480 Properties

49. Propeller Properties

50. Propulsion Parts List

51. Dimensions Main Wing Canard Vert. Stab. Airfoil USNPS-4 Flat Plate
Sref
3.58 ft2
0.31 ft2
0.63 ft2 AR
6.0
4.0
1.5
Taper Ratio
0.6
0.5
0.4
Sweep
0 deg.
25 deg.
Dihedral
3 deg.
---

52. USNPS-4 Characteristics

53. USNPS-4 Characteristics

54. USNPS-4 Characteristics

55. (assumed based on historical data and absence of naceles)
Parasite Drag Buildup
,where
Fuselage
,where
Form Factor:
Interference Factor:
(assumed based on historical data and absence of naceles)

56. Induced Drag Coefficient
Drag Buildup
Parasite Drag
Induced Drag Coefficient
(ref. Raymer)
Total Drag Coefficient

57. Parasite Drag Buildup Wings/Canards/Winglets Miscellaneous Drag
(1.02 accounts for thickness/curvature)
Form Factor:
Sweep correction:
Interference Factor:
(assumed based for mid-body, filleted wings)
Miscellaneous Drag
Based on historic small propeller aircraft

58. Total Drag Polar Prediction
Induced Drag Coefficient
Total Drag Coefficient

59. Lift Coefficient
Lift Curve Slope {

60. Lift Coefficient 3-D Lift Curve Slope 3-D CLmax
Full Aircraft Zero Degree AoA Lift Coefficient
-FlatEarth.m (ref. Roskam)
Taking into account:
Wing/Body interaction
Incidence Angles
Downwash

61. Flight Performance - Takeoff
Vtakeoff= 28 ft/s
ttakeoff = 2.7 s
Xtakeoff = 53 ft

62. Trim Diagram
SM=15%

63. Flight Performance - Turning

64. Flight Performance Endurance Climb
Need 489 mAh battery for 8 minute endurance
Battery selected provides 640 mAh (best available match to required capacity)
Climb
Motor selected to provide adequate power for design climb angle with selected prop

65. Lateral-Directional Root Locus
K = 0.95
*Negative Transfer Function

66. Closed-Loop Pulse Response
Rudder deflected 10 deg.
Rudder neutralized

67. Avionics
JR241 Servos for Rudder/Nose Wheel Steering, Elevator, Flaperons (1 ea.)
JR331 Servo for Retracts
Futaba GYA350 Gyro

68. Constraint Equations
Climb Power Loading
Stall Speed

69. Constraint Equations
Climb Power Loading
Stall Speed

70. Constraint Equations
Sustained Turning
Steady Flight

71. Bending Results Max Allowable Root Bending Moment
 lbf-ft (tensile failure)
Max Allowable Compressive Moment
 lbf-ft
Max Bending Moment in Loiter
 9.18 lbf-ft
Max Bending Moment in Turning Flight
9.73 lbf-ft

72. Foam Panels (nonstructural)
Fuselage Structure
Foam Panels (nonstructural)
Hollow
Balsa Box Structure
3/16” sq.
Balsa Stringers (4)
1/16” thick

73. Balsa Tristock Bracing
Vertical Stabilizer
3/16” x 1/4” Balsa Fin Structure, Solid Rudder
0.97 ft
0.37 ft
0.93 ft
Balsa Tristock Bracing

74. Balsa Leading Edge Spar
Wing Structure
Balsa Leading Edge Spar
Balsa Subspar
Balsa Wing Skin
Blue Foam Core
Balsa Trailing Edge
0.97 ft
0.03 ft
0.017 ft
0.10 ft
Foam Wing Saddle

75. Bending and Torsion Results
Ultimate Root Bending Moment lbf-ft (tensile failure)
Max Root Bending Moment in Turning Flight lbf-ft
Computed Factor of Safety = 3.3
Maximum twist angle = -0.2 (LE down)

76. Weight and Balance Origin at wing root c/4
Weight (lbs.)
Arm
(ft.)
Moment
(ft.-lbs.)
Airframe
0.856
-0.12
-0.10
Propulsion
0.666
0.12
0.08
Avionics
0.256
-0.98
-0.25
Landing Gear
0.155
-0.77
Miscellaneous
0.063
-0.16
-0.01
TOTAL
1.950
-0.51
Origin at wing root c/4
Nose-up moments are positive

77. Break Even Point Final Aircraft Price $228.28 Profit Margin 15%
MSRP of R/C Plane
$262.52
Profit Per Aircraft
$34.24
Units to Break Even
1,691

78. Materials Cost

79. Fabrication Plan Parallel construction process
Also bench test propulsion and avionics prior to installation

80. Backup charts Propulsion Aerodynamics Dynamics and Controls Structures
Economics and Fabrication Plan