Structures
Preliminary
Design Review
#1
Patrick Dempsey
October
12,
Bridget Fitzpatrick
2000
Heather
Garber
Keith Hout
Jong Soo Mok
Basic Layout of Wing
Spar
-located at the 1/4 chord
Sparcaps
-spruce
-1/8” x 1/8” x 6.6’
Shearweb
-balsa
-1.5” x 1/16” x 6.6’
Ribs
-balsa
-spaced every 3 inches from tip
-include lightening holes
Added balsa at leading and trailing edge
Geometric Layout of rib
Typical rib section
Geometric Layout of Wing
-Stringers
-None at this time
-Many model planes do not have them
-Would add weight
-Wing covering- Monokote
-Helps with twisting
-Forms the skin
Geometric Layout of Wing
Sample of strut layout from NACA report 143
Code
Code run using preliminary size of aircraft, load
factor, and a chosen spar size
-Wing loading
-Schrenk’s approximation (Raymer)
-Shear force
-Moment
-Find centroids
-Moments of inertia
-Normal stress
 My 

 xx  
 Iz 
WING LOADING
Trapezoidal approximation
2y

1   
q ( y )  q (0) 1 
b


q ( 0) 
w * 3.75
b
Elliptical approximation
q( y ) 
4S
 2y 
1   ^ 2
b * pi
 b 
SHEAR FORCE
MOMENT
Normal STRESS
Material Properties
Material
Balsa
Plywood
Spruce
Monokote (oz/sqin)
Epoxy (oz/sqin)
CA glue (oz/joint)
Young's
Modulus
(ksi)
Stress
Density
(yield)
(lbf/ft^3)
(psi)
625
11
1725
800
37
4000
1500
34
8600
0.0021
0.007
0.0068
Table taken from Spring ’99 AAE 451 report
(Team WTA)
Further Testing
-Test maximum shear stress of balsa using
three point load test
-Torsional test of wing with and without
monokote
Structure
-Fuselage - balsa
-Tapered box
-Modeled as truss structure
-Sheet on floor to hold equipment
-Horizontal/Vertical tail – balsa
-Modeled as a flat plate
-May have to add a spruce spar due to
the size of tail
Landing Gear
-Tail dragger configuration
-Front wheels placed in front of center of
gravity and to ensure propeller clearance
-Spaced horizontally to avoid lateral tip over
Center of Gravity Estimate
-Center of Gravity
-Within 5-10% static margin in front of
aerodynamic center
-Moment Balance
-Find the weight and moment arm of every
component
Questions?