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Rear spar for control surface hingesStyrene foam wing core
Balsa spars carry bending load 0.25 in x 0.25 in
T.E. Reinforcement
Materials Employed:
•Balsa: Light weight & Strong; Horizontal-Tail•Styrene Foam: Easily Workable;True airfoil shape•Composites: Fiber Glass Pods and hollow Carbon Fiber Booms•Assumptions: Load Carrying ability.
Structures
Mathematical Model
Assumptions:•Wing and Weight loading•Method of Analysis (Theoretical Model)•Safety Factor = 2.5g x 1.5
Wing
P
Boom
Horizontal Tail
Stress in the Wing
Sigmamax = 2003 psi
Sigmacritical = 1725 psi (Actual Test Result; Whiskey Tango Team, Spring 1999)
Reasons: Light Weight Structure (not Bulky) Safety Factor (worst case scenario) Wing Test Results
I
yMmaxmax
1.5ft
P
Horizontal Tail & Boom Horizontal Tail:Max Stress = 850psiSpar Sizes = 1/8 in x 1/16in
Booms:Max deflection = 0.24 inSF = 2.5g’s x 1.5 Assuming Young Modulus (E)
for aCarbon Epoxy matrix.Testing needed to verify result.
Moment Equations
2''
2'
22
LWLLxWL
xWLM o
oo
)( axPM
xLPM
Wing:
Horizontal Tail:
Boom:
12
.22
2''2' LWLLxWLxWLM ooo
Deflection Equations
4
.6
.24
)(22'3'4' xLWLxWLxWL
xEIv ooo
Lxafor
axPaxEIv
axforaxPx
xEIv
..6
3)(
0.6
3)(
2
2
6
)3()(
2 xLPxxEIv
241224
)(22'3'4' xLWLLxWLxWL
xEIv ooo
Wing:
Horizontal Tail:
Boom:
Structural Materials: Wing
Balsa•Light weight/very strong in compression and tension with the grain•Density = 11lb/ft3
•E= 625 ksi•Yield Stress = 1725 psi
Styrene Foam•Easily worked with hotwire or cutting tools•Gives true airfoil shape •Works well in compression when load is well distributed-serves as shear member•Not strong enough for bending loads•Density = 1.42 lb/ft3
Fiberglass
•Good for complex shapes
•Strong
•Skills needed
•3 layers of 1.5 oz cloth with resin = 9 oz/sq. yd.
Carbon Fiber
•Booms
•Light weight & Strong
Structural Materials:
Fuselage and Pods