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

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

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

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

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

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

What Materials to Use Titanium Bass / Spruce

Ref. www.towerhobbies.com Material Properties Titanium = difficult to obtain Wood = not difficult to obtain Ref. 1999 Forest Products Laboratory Wood Handbook Ref. www.towerhobbies.com

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

Twist at Tip

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

(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)

Chosen Spar Configuration Deflection at Tip Chosen Spar Configuration

(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)

Max Tension Stress

Max Compression Stress

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. www.towerhobbies.com

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

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

Questions?

Appendix Ref. Kuhn