1. CRITICAL DESIGN REVIEW
AAE 451
CRITICAL DESIGN REVIEW
TEAM 4
Jared Hutter, Andrew Faust, Matt Bagg, Tony Bradford,
Arun Padmanabhan, Gerald Lo, Kelvin Seah
December 9, 2003

2. OVERVIEW Introduction Aerodynamics Propulsion Structures
Aircraft Walk-Around
Design Requirements
Constraint Analysis
Aerodynamics
Propulsion
Structures
Dynamics and Control
Cost and Performance
Summary

3. INTRODUCTION

4. AIRCRAFT WALK-AROUND Empennage High Wing Avionics Pod Twin Booms
S = 39.3 ft2
b = 14.0 ft, c = 2.8 ft
AR = 5
Twin Booms
3 ft apart;
5.7 ft from Wing MAC to HT MAC
Twin Engine
1.8 HP each
Avionics Pod
20 lb; can be positioned front or aft depending on requirements
Empennage
Horizontal with Single Elevator;
Two Vertical Tails with One Rudder Each

5. Single Engine Performance Twin Engine Performance
DESIGN REQUIREMENTS
Parameter
Single Engine Performance
Twin Engine Performance
Customer Requirement
Endurance –
30 minutes
15 minutes
Payload Weight (Avionics Pod)
20 lbs
Gross Take-Off Weight
55 lbs
Climb Angle
> 0°
5.5°
Maximum Cruise Speed
 30 ft/s
60 ft/s
50 ft/s
Minimum Stall Speed
28 ft/s
30 ft/s
Maximum Operational Altitude (ASL)
2000 ft
1000 ft

6. CONSTRAINT ANALYSIS Original Numbers Final Numbers CL0= 0.30
CLMax= 1.3
CD0 = 0.03
ηp = 0.6
Final Numbers
CL0 = 0.39
CLMax = 1.58
CD0 =
ηp = 0.7

7. ORIGINAL CONSTRAINT DIAGRAM

8. FINAL CONSTRAINT DIAGRAM
(TWIN ENGINE)

9. AERODYNAMICS

10. AIRCRAFT CL AND CM Lift Coefficient CL = CL + CLe elevator + CL0
CL = [rad-1]  [rad-1] elevator
Moment Coefficient
CM = CM CMe elevator CM0
CM = [rad-1]  + ( ) [rad-1] elevator + 0.0

11. CL vs  & CL vs CMc/4

12. TRIM DIAGRAM

13. DRAG BREAKDOWN Part CD Main Wing 0.0132 Fuselage 0.0033 Tail 0.0108
Landing Gear
0.0008
Engines
0.0001
Stationary Propeller
0.0012

14. DRAG POLAR
Coefficient of Lift, CL
Coefficient of Drag, CD

15. PROPULSION

16. WHY TWIN ENGINES ? Clean Air for Air Data Boom
Unobstructed View for Camera
Survivability of the Pod

17. ENGINE SELECTION AND CHOICE
Sized engine based off of constraint diagram
Verified with thrust analysis
Engine Choice: Saito FA-100
Specifications:
Four Stroke Engine
Weight: 20.8 oz
Practical RPM: 2, ,300
Power: 1.8 ~9100 RPM
Fuel Consumption Rate: 1 max. RPM
Source:

18. FUEL SYSTEM Tank located in wing Filled from the top Dimensions:
3.25” high
4” wide
8” long
VP-20 Oscillating pump:
Weight: oz
Max. Flow Rate: oz/min
Fuel lines run externally underneath the wing

19. REQUIRED THRUST FOR SINGLE ENGINE CLIMB
Test for minimum requirement:
Flight Path Angle,  = 0.5
Drag = 7.5 lbf
Weight = 50.2 lbf
Thrust = Drag + Weight  sin()
= 8 lbf  W T D L V
PROPELLER SELECTION PROCEDURE
Ran various propeller geometries in Gold.m to meet thrust and horsepower requirements.
Chose propeller with highest propeller efficiency.

20. PROPELLER CHOICE Master Airscrew Propeller Made of glass-filled Nylon
Diameter: 16”
Pitch: 6”
Made of glass-filled Nylon

21. PROPELLER PARAMETERS T = 10.7 lbf T = 3.44 lbf /engine  6.88 lbf
Single Engine Climb
(V = 33.6 ft/s)
CP =
CT =
J = rev-1
HP = 9100 RPM
 = 37.5%
T = 10.7 lbf
Twin Engine Cruise
(V = 60 ft/s)
CP =
CT =
J = rev-1
HP = 7000 RPM
 = 70%
T = 3.44 lbf /engine  6.88 lbf

22. STRUCTURES

23. AIRCRAFT V-N DIAGRAM Load Limit at Max Speed
1-g at Level Flight Stall Speed
Load Limit at Max Speed
CLmax Constraints
Structural Constraints

24. MAIN WING Both box beams and I-beam configurations considered
Various materials analyzed
bitch
Final spar dimensions
Main: 3.7 in high by 2.0 in wide by 0.7 in thick
Rear: 1.8 in high by 0.9 in wide by 0.6 in thick

25. TAIL SECTION Modeled as beams under a distributed load
For rectangular beams:
Vertical Stabilizer Deflection
Horizontal Stabilizer Deflection q1 q2

26. TAIL SECTION
Deflection Curves
1 in  0.5 in
1 in  0.5 in

27. LANDING GEAR
MAIN
Purchasing all landing gears
REAR

28. LANDING GEAR Tip Over Analysis 14.03 ft 43 ° 43 ° 25 ° 10.1 °
Raymer Range: > 25 °
Raymer Range: 16 ° - 25 °
25 °
10.1 °
Raymer Range: 10 ° - 15 °

29. TAIL BOOMS Cylindrical Tubes Final tail boom dimensions:
Sized according to bending and torsional constraints
Bending:
Twist:
Set d = 2 in
Set f = 5 deg
Final tail boom dimensions:
Inner diameter: 1.6”
Outer diameter: 1.7”
Thickness: 0.05”
Length: 6.10 ft

30. POD ATTACHMENT
Four different analysis considerations in pod attachment (from Gere, Mechanics of Materials) :
1) allowable tensile stress in main base of connecting rail
2) allowable tensile stress around bolt holes
3) allowable shear stress in bolts
4) allowable shear stress in connecting rail
Only the 2) and 4) analyses are demonstrated

31. POD ATTACHMENT Tensile stress in bolt holes
Shear stress around bolt holes
= allowable shear stress of spruce (580 psi)
P = load we are designing for
d1 =width of hole section = 1.25 in
d2 =hole diameter = 3/8 in
t = rail thickness = 3/8 in
h = rail height = ¾ in
= 178 psi < 580 psi
= 370 psi (for spruce, tension perpendicular to grain)
= psi < 370 psi

32. AIRCRAFT LAYOUT
Total Weight = lbs

33. POD INTERNAL LAYOUT
Avionics + Structure = 20 lbs

34. POD ATTACHMENT METHOD

35. WING CONSTRUCTION
Wing + Required Structure = 13.1 lbs

36. CENTRAL WING INTERNAL LAYOUT

37. DETACHABLE SECTION INTERNAL LAYOUT

38. DETACHABLE SECTION INTERNAL LAYOUT

39. TAIL SECTION INTERNAL LAYOUT
Tail Section + landing gear = 1.59 lbs

40. REAR LANDING GEAR CONNECTION

41. WEIGHTS SUMMARY Component Weight (lbf) Wing & Structure 13.1
Tail Section & rear gear
1.59
Tail Booms
4.70
Basic Flight Systems
0.849
Propulsion & Fuel
6.61
Avionics & Structure 20
Main Landing Gear
2.36
Fiber-glass & Mylar Skin 1
Total Weight
50.21

42. DYNAMICS & CONTROL

43. MODIFIED CLASS 1 TAIL SIZING
Tail Volume Coefficient Approach (Raymer, p.124).
Equation used to find Horizontal Tail (HT) and Vertical Tail (VT) Areas:
Iterated until the following conditions are
satisfied:
Stability and control derivatives fall
within recommended range.
Ability to trim in yaw with rudder under
OEI flight conditions.
Results to be verified with stability in
aircraft responses.
where
HT Volume Coefficient
VT Volume Coefficient
Wing Chord, 2.8 ft
Wing Area, 39.3 ft2
Wing Span, 14.0 ft
Moment Arm, 6.1 ft

44. CLASS 1 CONTROL SURFACE SIZING
Chord-wise Span-wise
Ailerons 0.15 cW ~ 0.25 cW 0.5 bW ~ 0.9 bW
Elevator 0.25 cHT ~ 0.5 cHT ~ 0.9 bHT
Rudder 0.25 cVT ~ 0.5 cVT ~ 0.9 bVT
Raymer:
Choice of Values:
Chord-wise Span-wise
Ailerons cW ft
Elevator cHT ft
Rudder cVT bVT

45. TAIL SIZING RESULTS HORIZONTAL TAIL VERTICAL TAIL Chord-wise Span-wise
SHT = 9.01 ft2
1.01 ft
1.68 ft
½ = 2.03 ft2
= 0.6
1.51 ft
1.19 ft
3.0 ft
1.19 ft
AR = 3.2
5.37 ft
1.68 ft
Volume Coefficients:
= 0.50
= 0.045
Chord-wise Span-wise
Aileron ft 10.0 ft
Elevator ft 2.67 ft
Rudder cVT 2.42 ft

46. RUDDER DEFLECTION IN OEI CONDITIONS
Roskam (AAE 421 Textbook)
Required rudder deflection:
= 28 ft/s
Deflection Limit: = 25°
FAR 23, 25 requires that
for  = 0°
In this case, = ft/s
Max Deflection
FAR 23, 25 Limit
1.2
Stall Speed

47. C.G. LOCATION ESTIMATION
Aircraft C.G. location: x
Wing
W = 13.1 lb
x = 0.50 ft
Tail Gear
W = 0.55 lb
x = 7.0 ft
Avionics Pod
W = 20 lb
x variable
Main Gear
W = 2.3 lb
x = 0 ft
Tail Booms
W = 4.7 lb
x = 3.80 ft
Engines, Fuel & Casings
W = 6.6 lb
x = ft
Tail Section
W = 1.0 lb
x  7.0 ft

48. STATIC MARGIN CALCULATIONS
Aircraft aerodynamic center was calculated using:
Static margin:
Static Margin is a function of payload C.G. location.
Sensitivity study was conducted to examine the effect of the payload C.G. location on static margin.
0.810
[ fraction of MAC ]

49. SENSITIVITY STUDY Nominal Design Point where SM = 15% MAC
Payload of 20 lb,
with its x = +2.9 ft

50. MODAL ANALYSIS Lateral-Directional Subsystem Longitudinal Subsystem
Mode
Poles
Natural Frequency (rad/sec)
Damping Ratio
Dutch Roll
-3.89 ± j 2.00
4.37
0.89
Roll
-1.56
Spiral
-0.37
Mode
Poles
Natural Frequency (rad/sec)
Damping Ratio
Phugoid
-0.06 ± j 0.60
0.607
0.093
Short Period
-7.36, -73.3

51. 6-DOF SIMULATION WITH ELEVATOR STEP INPUT5°
Phugoid Mode
Short Period Mode
(non-oscillatory in this case)

52. 6-DOF SIMULATION WITH AILERON STEP INPUT
Roll Mode t a 5°

53. 6-DOF SIMULATION WITH RUDDER DOUBLET INPUT5°
-5°
Dutch Roll Mode

54. PERFORMANCE AND COST

55. PERFORMANCE - LEVEL FLIGHT
Min Thrust Required = ft/s
Min Power Required = ft/s
Max Speeds
Twin = 60 ft/s (limited by structures)
Single = 51 ft/s
Min Speeds
Twin = 28 ft/s (limited by stall)
Single = 38 ft/s

56. PERFORMANCE - LEVEL FLIGHT
Assume 1oz/min and 2.34 lb Fuel
Range
Endurance
Max Range = ft/s
Range at Min Thrust = ft/s
Range at Min Power = ft/s
Max Endurance = ft/s
Endurance at Min Power = ft/s

57. PERFORMANCE Climb Glide Climb Angle ()
At Best Rate of Climb: ft/s (Twin) o
4.8 ft/s (Single) o
At Best Angle of Climb: 11.4 ft/s (Twin) o
4.3 ft/s (Single) o
Best 50 ft/s
(L/D)max = 10.5
CL = 0.43

58. COST Propulsion 2 x Engine (Saito FA-100) 560 2 x Prop (Master 16 x 6)
19.8
Fuel (per gallon)
16.95
Fuel Tank (50 oz.)
11.49
2 x Fuel Feed Line (2 ft.)
3.7
2 x Engine Mounts
53.98
Total Propulsion
$665.92
Structure
2 x Main Gear (Robart #682)
150
2 x Tail Gear & Wheel Set
27.98
2 x Main Wheels
23.7
Total for Landing Gear
201.68
Monocoat (15 ft x 27 in.) / roll (need ft^2)
61.5
Balsa (3x3x6 in) block (need 5.33 ft^3)
128.25
Spruce (need ft^3)
40.63
Fiberglass (50wide x 36vary in) 10
2 x Aluminum Booms (6061 T6) 8 ft each
51.2
Total Materials
291.58
Total Structure
$493.26
Controls
Futaba 9CAP 9ch PCM with
4 S3001 servos
479.99
Servos 3xS3001
79.97
Total Controls
$559.96

59. COST Total Aircraft Cost $15100.94 Total Payload 12321.8
Total Propulsion
665.92
Total Structure
493.26
Total Controls
559.96
Total Labor (No Engineering)
960.00
Total Miscellaneous (Nuts, Bolts, Hinges, etc.)
100.00
Total Aircraft Cost $

60. TOTAL COST

61. SUMMARY

62. TOP VIEW
14.03 ft
2.81 ft
AR = 5
3.00 ft
6.10 ft
5.37 ft
1.68 ft

63. PROFILE VIEW
1.01 ft
1.51 ft
2.81 ft
1.74 ft
6.10 ft

64. FRONT VIEW
14.03 ft
3.00 ft

65. QUESTIONS?

66. APPENDIX

67. Modulus of Elasticity (ksi)
MATERIAL PROPERTIES
Material
Density (lb/ft3)
Modulus of Elasticity (ksi)
Al 2024-T6
178.2
10500
Balsa 11
490
Basswood
24.9
1500
Spruce
24.5
1230
Foam
1.43 -
Sources: -
- US Dept. of Agriculture

68. WING ANALYSIS Actual bending moment at each point along spar
Root Bending Moment = ft-lbf
Actual bending moment at each point along spar
Based on lifting line theory

69. WING ANALYSIS

70. WING ANALYSIS
508.5 ft-lbf

71. TAIL BOOM SIZING

72. VERTICAL TAIL Bending moment decreases from root to tip
Increasing
deflection
Deflection greatest
at tip

73. POD ATTACHMENT Tensile Stress in Main Base
As seen from left rear view of pod
Tensile Stress in Main Base
where: P = load we are designing for
= allowable tensile stress in material
A = area under inspection
d2= hole diameter
t = rail thickness
= 370 psi (for spruce, tension perpendicular to grain)
d2= 3/8 in
t = 3/8 in
P = 50 lbf

74. POD ATTACHMENT Solve for and make sure it’s less than that for spruce
=355.6 psi < 370 psi

75. POD ATTACHMENT Shear stress experienced in bolts
As seen from left rear view of pod
Shear stress experienced in bolts
where
= allowable shear stress in bolts
n = number of bolts required
= 91 psi
from plasticnutsandbolts.com

76. POD ATTACHMENT
This time, solve for n and find how many bolts are required for the given allowable shear stress and load P
n = 5, but use 6 for symmetry

77. LANDING GEAR ANALYSIS Gear modeled as spring-mass damper Mass, m
Spring constant, k
Damping constant, c
Mass, m

78. LANDING GEAR ANALYSIS Equation of motion: State space representation:
Where d2x/dt2 = vertical acceleration
dx/dt = vertical velocity
x = vertical position
k = spring constant
c = damping coefficient
State space representation:
Used values of:
k = 305 lbm/s2
c = 40 lbm/s
m = 1.70 lbm (W = 54.6 lbf)
to be verified with manufacturer

79. LANDING GEAR ANALYSIS State space representation modeled in MATLAB
Use ode45 to obtain position, velocity, and acceleration data
Find the vertical force applied to the 2 main gears

80. LANDING GEAR ANALYSIS Modeled vertical velocity = 6 ft/s
Maximum displacement = 2.1 in

81. LANDING GEAR ANALYSIS
- Modeled vertical velocity = 6 ft/s

82. LANDING GEAR ANALYSIS
- Modeled vertical velocity = 6 ft/s

83. LANDING GEAR ANALYSIS
Design joint for lb vertical compressive load
- Modeled vertical velocity = 6 ft/s

84. LANDING GEAR – SCHEMATIC

85. RUDDER DEFLECTION IN OEI CONDITIONS
ref. “Airplane Flight Dynamics and Automatic Flight Controls” (Roskam) Section 4.2.6
[rad]
where
@ 2,000 ft
 [slug/ft3]
V [ft/sec]
P [hp]
yT [ft]
for fixed pitch

86. AIRCRAFT AERODYNAMIC CENTER
The following equation was used:
ref. “Airplane Flight Dynamics and Automatic Flight Controls” (Roskam) Equation 3.38
where = 0.25 = 2.78
= 6.19 rad-1
= 6.01 rad-1 = 0.45
= 9.01 ft2
= ft2 = 2.22
ref. “Airplane Design, Volume VI” (Roskam) Equation 8.45

87. MIL-F-8785C GUIDELINES Lateral-Directional Subsystem
Longitudinal Subsystem
Mode
Poles
Natural Frequency (rad/sec)
Damping Ratio
Dutch Roll
-3.89 ± j 2.00
4.37
0.89
Roll
-1.56
Spiral
-0.37
 0.4, OK!
 0.08, OK!
Stable, non-oscillatory – OK!
Stable, does not diverge – OK!
Mode
Poles
Natural Frequency (rad/sec)
Damping Ratio
Phugoid
-0.06 ± j 0.60
0.607
0.093
Short Period
-7.36, -73.3
“Must be heavily damped” – OK!

88. PERFORMANCE APPENDIX

89. PERFORMANCE APPENDIX

90. COST BREAKDOWN