Spreadsheet for estimating the strength of steel, aluminum and wood columnsWritten by Neal Willford 11/6/2004 for Sport AviationBased on methods in "Analysis & Design of Flight Vehicle Structures" by Bruhn and ANC-18 "Design of Wood Aircraft Structures"Estimates assume pinned connection at end points***This spreadsheet is for educational purposes only and may contain errors. Any attempt to use the results for actual design purposes are done at the user's own risk ***For streamlined tubes, use the equivalent diameter for compression shown in supply catalogs for the given streamline tubeInput required in the yellow cells

4130 ROUND Steel Tubing

Tubing Diameter: 0.50 inches Area =Tubing Thickness: 0.035 inches Moment of Inertia =Tubing Length: 27.00 inches (distance between end points) radius of gyration (rho) =Tube weight = 0.39 lbs Length/rho =Ftu = 95000 psi (ultimate tensile stress)Fco = 79500 psi (yield compressive stress) Column buckling stress =

For tubes in compression For tubes in tensionMaximum compressive strength = 545 lbs Maximum tensile strength =Ultimate design compressive load: 525 lbs Ultimate design tension load:Margin of Safety = 4% Margin of Safety =

2024-T3 ROUND Aluminum TubingD/t =

Tubing Diameter: 0.63 inches Area =Tubing Thickness: 0.058 inches Moment of Inertia =Tubing Length: 27.00 inches (distance between end points) radius of gyration (rho) =Tube weight = 0.28 lbs Length/rho =Ftu = 62000 psi (ultimate tensile stress) Transition Length/rho =Fco = 50607 psi (yield compressive stress) Column buckling stress =

For tubes in compression For tubes in tensionMaximum compressive strength = 596 lbs Maximum tensile strength =Ultimate design compressive load: 525 lbs Ultimate design tension load:Margin of Safety = 14% Margin of Safety =

6061-T6 ROUND Aluminum TubingD/t =

Tubing Diameter: 0.63 inches Area =Tubing Thickness: 0.058 inches Moment of Inertia =Tubing Length: 27.00 inches (distance between end points) radius of gyration (rho) =Tube weight = 0.27 lbs Length/rho =Ftu = 42000 psi (ultimate tensile stress) Transition Length/rho =Fco = 39509 psi (yield compressive stress) Column buckling stress =

For tubes in compression For tubes in tensionMaximum compressive strength = 574 lbs Maximum tensile strength =Ultimate design compressive load: 525 lbs Ultimate design tension load:Margin of Safety = 9% Margin of Safety =

Wood ColumnsSpruce Douglas Fir

Modulus of Elasticity (psi) 1300000 1700000Density (lbs/cu. In.) 0.01563 0.01968Ultimate Compressive Stress (psi) 5000 7000Ultimate Tensile Stress (psi) 9400 11500

Width: 0.88 inches Area =Height: 0.75 inches Moment of Inertia =Tubing Length: 27.00 inches (distance between end points) radius of gyration (rho) =Enter material properties for the wood being considered: Length/rho =Modulus of Elasticity: 1300000 psi Critical Length/rho =Density: 0.0156 lbs/cu. In.Ult Comp.Stress: 5000 psiUlt Tensile Stress: 9400 psi Column buckling stress =Column weight = 0.28 lbs

For member in compression For member in tensionMaximum compressive strength = 549 lbs Maximum tensile strength =Ultimate design compressive load: 525 lbs Ultimate design tension load:Margin of Safety = 4% Margin of Safety =

Based on methods in "Analysis & Design of Flight Vehicle Structures" by Bruhn and ANC-18 "Design of Wood Aircraft Structures"

***This spreadsheet is for educational purposes only and may contain errors. Any attempt to use the results for actual design purposes are done at the user's own risk ***For streamlined tubes, use the equivalent diameter for compression shown in supply catalogs for the given streamline tube

0.051 sq. inchesMoment of Inertia = 0.001 inches^4radius of gyration (rho) = 0.16 inches Length/rho = 164

10664 psi (for the given column dimensions)

For tubes in tensionMaximum tensile strength = 4857 lbsUltimate design tension load: 525 lbsMargin of Safety = 825%

10.8 Fcc = 49325 psi0.103 sq. inches

Moment of Inertia = 0.004 inches^4radius of gyration (rho) = 0.20 inches Length/rho = 134Transition Length/rho = 78

5772 psi (for the given column dimensions)

For tubes in tensionMaximum tensile strength = 6405 lbsUltimate design tension load: 525 lbsMargin of Safety = 1120%

10.8 Fcc = 39645 psi0.103 sq. inches

Moment of Inertia = 0.004 inches^4radius of gyration (rho) = 0.20 inches Length/rho = 134Transition Length/rho = 68

5553 psi (for the given column dimensions)

For tubes in tensionMaximum tensile strength = 4339 lbsUltimate design tension load: 525 lbsMargin of Safety = 727%

0.656 sq. inchesMoment of Inertia = 0.031 inches^4radius of gyration (rho) = 0.22 inches Length/rho = 125Critical Length/rho = 62

836 psi (for the given column dimensions)

For member in tensionMaximum tensile strength = 6169 lbsUltimate design tension load: 525 lbsMargin of Safety = 1075%