1. Structures PDR #1 AAE451 – Team 3 October 28, 2003
Brian Chesko
Brian Hronchek
Ted Light
Doug Mousseau
Brent Robbins
Emil Tchilian

2. Introduction Updated Weight Code Geometric Layout of Wing Structure
Spar geometry, materials chosen, & location
Material Properties
Analysis of Wing Loads
Twisting Moments
Deflection at Tip
Future Analysis

3. Weight Calculation Process
Initial guess at size and weight of aircraft with given geometry
For initial weight, wing resized for stall speed requirement
Plane resized around new wing size
Weight of aircraft updated
Process repeated until convergence

4. Weight Code Results P AR set at 5 Span ~ 14 ft Chord ~ 2.8 ft
Weight ~ 49 lbs P

5. Ref. Niu, Airframe Structural Design
Wing Structure
Spar(s) Configuration
2 spars make convenient attach points for additional structure (similar to wing box)
Spar locations based on historical data
Front Spar ~ 15% of chord
Rear Spar ~ 60% of chord
Material Selection
Object of a trade study
Ref. Niu, Airframe Structural Design

6. Spar Cross Section h h t t Difficult to manufacture
Difficult to analyze
Ugly
Easy to manufacture
Easy to analyze
Pretty

7. What Materials to Use
Titanium
Bass / Spruce

8. Ref. www.towerhobbies.com
Material Properties
Titanium = difficult to obtain
Wood = not difficult to obtain
Ref Forest Products Laboratory Wood Handbook
Ref.

9. Twist Constraint (<1o)
Ref. Kuhn pg. 49
Where T = Torque (in-lbf)
L = Length (in)
l = f(B0, A0) (ref. Appendix)
A0 = f(E, I) (ref. Appendix)
B0 = f(G,J) (ref. Appendix)
E = Young’s Modulus (psi)
I = Moment of Inertia (in4)
G = Torsional Stiffness (psi)
J = Polar Moment of Inertia (in4)
Assumptions:
Small Deflections
Spars & Ribs Carry all Torsion
Span ~ 14 ft
Chord ~ 2.8 ft
Safety Factor = 1.5
G-Loading = 5.0
Weight = 49 lbs
Ref. Gere

10. Twist at Tip

11. Twist at Tip (Zoom) Chosen Front Spar = 0.73” thick
Chosen Rear Spar = 0.25” thick

12. (based on span-wise lift distribution)
Deflection at Tip
Load (lbf)
Ref. Gere pg. 892
a (in)
Where Load = Weight*SF*G-loading (lbf)
L = Length (in)
E = Young’s Modulus (psi)
I = Moment of Inertia (in4)
L (in)
Assumptions:
Small Deflections
NO TORSION
Span ~ 14 ft
Chord ~ 2.8 ft
Safety Factor = 1.5
G-loading = 5.0
Weight = 49 lbs
For this design:
a = 3 ft or 36 in
(based on span-wise lift distribution)

13. Chosen Spar Configuration
Deflection at Tip
Chosen Spar Configuration

14. (based on span-wise lift distribution)
Is Stress too High?
Load (lbf)
Ref. Gere pg. 323
a (in)
Where M = Weight*SF*G-loading*a (in-lbf)
y = Maximum Dist from Neutral Axis (in)
I = Moment of Inertia (in4)
L (in)
Assumptions:
Span ~ 14 ft
Chord ~ 2.8 ft
Safety Factor = 1.5
G-loading = 5.0
Weight = 49 lbs
For this design:
a = 3 ft or 36 in
(based on span-wise lift distribution)

15. Max Tension Stress

16. Max Compression Stress

17. Ref. www.towerhobbies.com
Covering
Traditional Monocote may not be strong enough for these large aircraft
Coverite 21st Century Iron on Fabric is stronger, and resists tears much better
0.34 oz/ft2
Approx. 2 lbs for entire wing
Ref.

18. Summary Main Wing Spruce or Bass wood Front Spar Rear Spar Weight
0.73” thick by 3.6” high
Rear Spar
3/8” thick by 3” high
Weight
~5.9 lbs for front spar
~1.6 lbs for rear spar h t

19. Future Analyses Landing gear Keep updating weight & C.G. estimate
Strength analysis
Tip-over analysis
Keep updating weight & C.G. estimate
Tail assembly analysis
Similar to wing analysis
Fuselage construction
Materials

20. Questions?

21. Appendix
Ref. Kuhn