Redesign of the STOL CH 701 Landing Gear Strut Group Members: Peter Chiu Cameron Clark Dave Maharaj Okason Morrison

Problem Definition Design a single-piece double cantilever leaf spring capable of surviving the landing conditions set forth by the FAR.

Specifications Descent velocity range 7 - 10 ft/s (2.134 m/s - 3.048 m/s) Descent load factor range 1.67g – 2.67g Wing Area 122 ft2 (11.2 m2) Empty Weight 580lbs (263 kg) Gross Weight 1,100 lbs (500 kg) Payload 520 lbs (236 kg) Max Reaction Load on tire 1350 lbs (6005 N) Tire Diameter 16 in (0.406 m)

Theoretical Analysis 1: Newton’s Equation of Motion

Assumptions Plane can be treated as point mass Constant deceleration (vertical component only) Neglecting material properties Plane has zero final velocity

Calculations sstrut stire The displacement, s is a function of 2 variables: u & a sstrut = f (u, a) surface plot

Maximum Displacement: 3-d S is max at a =1.67g u= 10 ft/s Sstrut(max) = 212 mm (8.36 in)

Theoretical Analysis 2: Beam Deflection

Geometry Simplification Strut can be modeled as a cantilever beam Only a portion of strut needs to be analyze due to symmetry Beam subjected to 1 load and 1 moment X Y Ry  M R = 1350 lbs

Deflection Equations

Deflection Equations 2 h b

Beam Analysis Width Suitable strut width  65 mm (2.6 in)

Finite Element Analysis

Modeling Material: Al 2014 σyield: 414 MPa

Optimization Study

Engineering Drawings of Final Design

Deflection Video

Deflection Sstrut(max) = 45 mm (1.77 in)

Von Mises Stress σvm: 307 MPa S.F. = 1.3

Summary Table Material Al 2014 Strut Width 120 mm Strut Height 354 mm Strut thickness 17 – 20 mm Max Strut Deflection (Newton’s Law) 212 mm Max Deflection (Beam Analysis) 111 mm Max Deflection (FEA) 45 mm Max Von Mises 307 MPa Yield Strength 414 MPa Safety Factor 1.3 % of max allowable Displacement 14.2 %

Questions