Team One
Structures and Weights
PDR 2
03 March, 2005
Speakers
Todd Mostrog
Chris Grupido
Daniel Halla
John Apostol
Team One
03 March, 2005
Overview
Load Factor Selection
Load Conditions
Torsional Analysis
Bending Analysis
Structural Design
Wing
Fuselage
Tail Section
Weight Estimation
Landing Gear Design
Team One
03 March, 2005
Load Factors
Maximum Load Factor, nmax
2W
V2
For CLmax of Wing = 1.24 and
Wing Area = 2.2 ft2
Stall Speed : VSTALL = 20 ft/s : nmax = 1.00
Take-off Speed : VTO = 24 ft/s : nmax = 1.44
Turn Speed : VTURN = 25 ft/s : nmax = 1.56
Loiter Speed : VLOIT = 30 ft/s : nmax = 2.26
Max Speed : VMAX = 40 ft/s : nmax = 4.01
4.5
4
3.5
Max Load Factor
nmax 
CLmax S
V-n Diagram
3
2.5
2
1.5
1
0.5
0
0
5
10
15
20
25
30
35
Velocity (ft/s)
Team One
03 March, 2005
40
45
Load Factors
Turn Considerations
Turn Radius vs. Bank Angle
n  1 cos 
40
35
n
Turn Radius
(ft)
30
1.15
34.18
45
1.41
19.53
60
2.0
11.21
75
3.86
5.21
30
Turn Radius (ft)
Bank Angle
(deg)
25
20
15
10
5
0
20
30
40
50
60
70
Bank Angle (deg)
Team One
03 March, 2005
80
Load Factors
Vertical Turn / Loop Considerations
-Considered for Loiter Speed : V = 30 ft./sec.
Vertical Turn Radius vs. Load Factor at Loiter Speed, V = 30 ft/sec
160
-For Pull – Up
Pull - Up
140
2
-For Velocity Vector Vertical
V2
n
gr
- For Pull - Down
V2
 n 1
gr
Vel. Vector Vert.
Vertical Turn Radius (ft.)
V
 n 1
gr
120
Pull - Down
100
80
60
40
20
0
0
1
2
3
4
5
Load Factor
Team One
03 March, 2005
6
Load Factors
Conclusions
Load Factor of 2.4 chosen
Aerobatics Performed at Loiter Speed or Below
Max Speed for Level Dash Only
Max Bank Angle of 60 degrees
Turn Radius of 11.21 ft.
Vertical Turn Radius:
Pull-Up : 19.97 ft.
Velocity Vector Vertical : 11.65 ft.
Pull-Down : 8.22 ft.
Team One
03 March, 2005
Load and Moment
Conditions
For Maximum Load Factor of 2.4 and Weight of 1.3 lbf
Maximum Load = 3.12 lbf
Lift Distribution on Wing is 83% Elliptical
- Centroid of Elliptical Parabolic Semisegment : x = 3/8 base
- Assumed Resultant Loading at ½ Wing Section Span
x = ½(b/2) = ½(3.85 ft. / 2) = 0.96 ft.
Maximum Bending Moment at Root Chord
M = 1.5 ft.-lbf = 17.97 in.-lbf
Team One
03 March, 2005
Torsional Analysis
Twist Angle Equation
1
qds

2 Ai G celli t
For Root Chord = 5.04 in.
Shear Flow = 0.33 lb. \ in.
Shear Stress = 330 psi
Torque Applied = 9.52 lb.-in.
For Twist of 1 deg :
Twist Angle = 0.0015 rad/in.
For Monokote Skin
t = 0.001 in. and G = 406 ksi
For Tip Chord = 9.28 in.
Shear Flow = 0.204 lb. \ in.
Shear Stress = 204 psi
Torque Applied = 0.47 lb.-in.
Team One
03 March, 2005
Modeling
Assumptions
Simplifying Assumptions
Wing loading
Concentrated lift force
Centroid of a semi-segment of nth degree 3/8 span
Originally modeled at .5 span -- maintained
Effect of landing gear weight ignored
Wing Geometry
Sized from bending analysis
Constant size spars
Team One
03 March, 2005
General Construction
Wing and Fuselage
Traditional rib and stringer construction
Balsa leading edge
All stringers are 0.125” square
Tail Assembly
Solid Balsa
Monokote Covering
0.001 thick
Grade “B” Balsa (trade study pending)
Hidden fixed gear with 4 tires
Foam main wheels
0.02 lbs (pair)
Tail wheels
Manufactured
Team One
03 March, 2005
Wing/Tail Properties
Wing
3.7 ft. Span
Weight =0.12 lbf
Polar Moment of Inertia = 0.0074 in.4
Maximum Moment
17.97 in.-lbf (2.4 gs)
0.67 in. max deflection
Spars
(2) 0.125 X 0.5 (average)
20 Ribs
2.2 in. Separation
2 Stringers
Solid Tail Section
31.74 in.3
0.17 lbf
Team One
03 March, 2005
Wing Geometry
Team One
03 March, 2005
Fuselage Properties
3 in. diameter
25 in. length
Weight = 0.05 lbf
Polar Moment of Inertia = 0.018 in4
Maximum Moment
19.2 in.-lbf
J = 0.054 in4
0.36 degrees/inch of twist
6 Ribs
4.18 inches of Separation
12 stringers spaced 30 degrees apart
Team One
03 March, 2005
Fuselage Geometry
Team One
03 March, 2005
Landing Gear
1 ¾” diameter foam wheels (2)
Fixed to wing ribs
Designed for no failure
Top half hidden in wing section picture of this below
Team One
03 March, 2005
Landing Gear
Main Considerations
Four points of contact
Increases on ground stability
Aft landing gear on tail
Rudder mounted for ground directional control
Forward landing gear in wing
Simple structure attachment
Reduce drag
Team One
03 March, 2005
Landing Gear
Main Concerns
Forward tip over
Location of center of gravity close to location of forward point of
contact
Rudder mounted aft gear
Strength of rudder to avoid failure
In wing forward gear
Limits allowable propeller size
Team One
03 March, 2005
Landing Gear
Tip-over Analysis
In wing mounted gear
Low center of gravity
5-10 degrees before wing
strike
Tail mounted gear
Initial positive rest angle
5-10 degrees
Team One
03 March, 2005
Increasing Weight
Center of Gravity
5
6
Number
Part
1
Motor
2
Batteries
3
Wing
4
Wheels
5
Aileron
Servos
6
Speed
Controller
7
Fuselage
8
Gyro
9
Mixer
10
Receiver
11
Tail Servos
Xc.g. = 0.20 * Aircraft Length
12
Tail
Zc.g. = 0.55 * Aircraft Height
13
Tail Gear
7 89
11
13
12
10
4
3
1
2
n
CG 
Team One
Wx
n1
Wi
i
Centers of Gravity
i
03 March, 2005
Moments of Inertia
Equations to solve MOI
Ixx   ( y 2  z 2 )dm
Mass Moments of Inertia
Iyy   ( x 2  z 2 )dm
Iyy = 0.041 lb-ft2
m
m
Izz   (x  y )dm
2
2
Ixx = 0.0019 lb-ft2
Izz = 0.0181 lb-ft2
m
Team One
03 March, 2005
Products of Inertia
Equations to solve for POI
Ixy  Iyx   ( xy )dm
m
Iyz  Izy   ( yz )dm
Mass Product of Inertia
m
Ixz = 0.0779 lb-ft2
Ixz  Izx   ( xz )dm
m
Since aircraft is symmetrical around y-axis plane:
Ixy = Iyz = 0
Team One
03 March, 2005
List of Parts
Part
Description
Weight (lbs)
Motor
Graupner SPEED 500 7.2 V (ungeared)
0.36
Batteries
Kokam Li-Poly 2-cell 1250 mAh x 2
0.365
Wing
Grade B (Medium) Balsa Wood
0.09
Main Landing Gear
LYT 1 ¾” Foam Wheels x 2
0.020
Aileron Servos
JR Mini 311 x 2
0.082
Speed Controller
Castle Creations PIXIE-20P
0.018
Fuselage
Grade B (Medium) Balsa Wood
0.02
Gyro
GWS PG03 Piezo Gyro
0.0125
Mixer
Vee Tail OMNI
0.0126
Receiver
JP 6-Channel
0.038
Tail Servos
JR Mini 311 x 2
0.082
Tail
Grade B (Medium) Balsa Wood
0.03
Tail Landing Gear
Lexan EM1210 Polycarbonate x 2
0.0024
Team One
03 March, 2005
Parts Location
Number
Part
Motor
Batteries
Wheels
Aileron
Servos
Speed
Controller
Gyro
Mixer
Receiver
Tail Servos
Tail Gear
Team One
03 March, 2005
Questions or Comments?
Team One
03 March, 2005