final wing design

M E 6 3 0 0 : A E R O S P A C E S T R U C T U R E S G A B R I E L H E R E D I A A C E V E D O

J O N A T H A N H O L G U I N O B O R D A

FINAL WING DESIGN

Picture Reference: http://www.cessna.com/~/media/Images/Aircraft/citation/mustang/gallery/exterior/img-

gallery-must-2.ashx

AGENDA

Problem presentation and purpose.

Proposed solutions.

Pugh’s decision matrix.

Design parameters and materials.

Initial load summary (proposed solutions).

Detailed design summary (prevailing model).

Conclusions, additional comments, and references.

PROBLEM PRESENTATION

Design wing structure for an 8,000lb aircraft with 20ft wingspan.

Must conform to FAR23-Subpart C Loading Conditions.

Cruise speed 285mph.

Diving speed 399mph.

Picture Reference:

http://www.darcorp.com/img/far23_leftbar.png

Picture Reference: http://www.charterjets.com/_images/aircraft/citation_

x_750_exterior.jpg

MODEL PROPOSALS

Three Cell Web-Stringer

Picture Reference: AutoCAD Civil 3D Educational

Version Drawing

Picture Reference: AutoCAD Civil 3D Educational

Version Drawing

Two Cell Web-Stringer

Truss Model

Picture Reference: AutoCAD Civil 3D Educational

Version Drawing

PUGH’S DECISION MATRIX

Pro

ble

m S

tate

me

nt

Structures Design of wing type Airfoil - NACA 0012

We

igh

tin

g

Alte

rna

tive

s

Two

Ce

ll W

eb

-Str

ing

er

Thre

e C

ell W

eb

-Str

ing

er

Tru

ss S

tyle

Fra

me

Crite

ria

Weight 25 1 0 -1

Stiffness 15 -1 0 1

Mechanical Resistance 20 0 1 -1

Manufacturability 15 1 0 -1

Maintenance 10 1 0 -1

Cost 15 1 0 -1

Total: 100 50 20 -70

*Green denotes controlling design

DESIGN PROCESS

Design Parameters

Shear Flow Analysis

Principal Stringer

Analysis

Rivet Spacing

Fatigue Analysis Crippling Analysis Aero-elasticity

Analysis

Final Design

Buckling Analysis

DESIGN PARAMETERS & MATERIAL PROPERTIES

NACA-0012 Airfoil profile.

Picture Reference:

http://www.pointwise.com/theconnector

/July-2012/SAE-Fig1-Airfoils-2400x1800.png

Dimensions.

Picture Reference: “Aircraft Wing Load

Analysis Proyecto Final.xlsx”

Trapezoidal Wing Platform

Cr 102 in

Ct 63.75 in

b/2 240 in

Aircraft-Air Interaction Data

Wing-Tail Distance 200 in

Air Density 0.002377 slugs/ft3

Aircraft Weight 8,000 lbs

Cruising Speed 285 mph

Diving Speed 399 mph

*Data Reference: Design Requirements

Aluminum 7075-T6

σYield

(psi) σUltimate

(psi) τYield

(psi) γ

(lb/in3)** ν **

C (Fatigue Constant)

N (Fatigue Constant)

67,000 76,000 33,500 0.1 0.33 2.13E-13 3.21

Aluminum 2024-T3

σYield

(psi) σUltimate

(psi) τYield (psi)

E (ksi) **

G (ksi) **

C (Fatigue Constant)

N (Fatigue Constant)

42,100 63,800 21,050 10,400 4,000 3.22E-14 3.38

Material Properties References: www.matweb.com, “Effect of Stress Ratio on Fatigue-Crack Growth in 7075-T6 and 2024-T3

Aluminum-Alloy Specimens” (Michael Hudson, NASA Technical Note August 1969)

** E, G, γ, and ν are virtually the same for both materials.

WING APPLIED LOADS

*Graphs Reference: “Aircraft Wing Load Analysis Proyecto Final.xlsx”

(“Wing Load Distribution” Sheet)

Loads obtained using Schrenck’s Approximation method and FAR-23 Subpart C.

890

1,229 1,405

1,544 1,660

1,759 1,845

1,920 1,985 2,042 2,090 2,131

0

500

1,000

1,500

2,000

2,500

1 2 3 4 5 6 7 8 9 10 11 12

Str

ip L

oa

d (

lbf)

Wing Station (strip)

Vertical Wing Load

0.50

0.82

0.92

0.98 1.01

1.04 1.05 1.06 1.06 1.05 1.04 1.03 1.02

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1.10

0 20 40 60 80 100 120 140 160 180 200 220 240

Sh

ren

k's

Win

g-S

pa

n L

ift

Fa

cto

r

(cl1

i)

Wing Coordinate (in)

Shrenk's Lift Factor

WING INTERNAL LOADS

2,170,482

1,781,814

1,435,361

1,130,232

865,373

639,564

451,400 299,269

181,321 95,406 38,984 8,899 0

Mz = 44.05291760x2 - 19,442.43869525x +

2,151,888.56198930

R² = 0.99967998

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

0 20 40 60 80 100 120 140 160 180 200 220 240

Mo

me

nt

(lb

f-in

)

Wing Coordinate (in)

Moment Diagram

0 -890

-2,118 -3,524

-5,068 -6,727

-8,486

-10,331

-12,250

-14,236

-16,277

-18,368

-20,499

V = -0.1212x2 + 116.22x - 20658

-25,000

-20,000

-15,000

-10,000

-5,000

0

0 20 40 60 80 100 120 140 160 180 200 220 240

Sh

ea

r Fo

rce

(lb

f)

Wing Coordinate (in)

Shear Force Diagram

*Graphs Reference: “Aircraft Wing Load Analysis Proyecto Final.xlsx”

(“Wing Load Distribution” Sheet)

Loads obtained using Schrenck’s Approximation method and FAR-23 Subpart C.

TWO-CELL STRUCTURAL BOX

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Version Drawing

TYPICAL CROSS-SECTIONS

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Version Drawing

WINGWARD PROFILE

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Version Drawing

WINGWARD ORTHOGONAL VIEW

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Version Drawing

MARGINS OF SAFETY (AXIAL STRESS)

Stringer σz (psi) M.S. Yield

Aluminum

7075-T6

M.S. Yield

Aluminum

2024-T3

M.S. Ultimate

Aluminum

7075-T6

M.S. Ultimate

Aluminum

2024-T3

1 63,568.56 36.75% -0.66% 16.36% 0.36%

2 -63,568.56 36.75% -0.66% 16.36% 0.36%

3 -61,602.67 38.70% 2.45% 18.94% 3.44%

4 -39,944.95 60.25% 36.75% 47.44% 37.39%

5 39,944.95 60.25% 36.75% 47.44% 37.39%

6 61,602.67 38.70% 2.45% 18.94% 3.44%

*Table Reference: “Aircraft Wing Load Analysis Proyecto Final.xlsx”

(“Summary” Sheet)

*Green denotes controlling margin of safety for this criterion

MARGINS OF SAFETY (SHEAR FLOW)

*Table Reference: “Aircraft Wing Load Analysis Proyecto Final.xlsx”

(“Summary” Sheet)

*Green denotes controlling margin of safety for this criterion

Element τxy (psi) M.S. Shear Aluminum

7075-T6 M.S. Shear

Aluminum 2024-T3

12(1) -3,205.85 83.42% 73.62%

12(2) -12,230.96 36.76% -0.64%

23 -3,039.50 84.28% 74.99%

34 3,371.64 82.57% 72.26%

45 16,256.78 15.95% -33.77%

56 3,371.64 82.57% 72.26%

61 -3,039.50 84.28% 74.99%

MARGINS OF SAFETY (BUCKLING)

*Table Reference: “Aircraft Wing Load Analysis Proyecto Final.xlsx”

(“Summary” Sheet)

*Green denotes controlling margin of safety for this criterion

Stringer σz (psi) M.S. Buckling Element M.S. Buckling Skin

1 63,568.56 17.09% 12(1) 90.11%

2 -63,568.56 17.09% 23 91.27%

3 -61,602.67 81.66% 34 91.27%

4 -39,944.95 18.80% 56 89.02%

5 39,944.95 18.80% 61 89.02%

6 61,602.67 81.66%

MARGINS OF SAFETY (FATIGUE & AERO-ELASTICITY)

*Tables Reference: “Aircraft Wing Load Analysis Proyecto Final.xlsx”

(“Summary” Sheet)

*Green denotes controlling margin of safety for this criterion

Element M.S. Fatigue Skin

23 27.13%

34 0.51%

Aero-elasticity M.S. Diverging

Speed

Wing 98.74%

SECTION SUMMARY

Section Additional Comments

Principal Stringers

1, 2 L2.5X2X5/16 Aluminum 7075-T6

3, 6 3x1.5x5/16 Aluminum 7075-T6

4, 5 L1.5x1.5x5/16 Aluminum 7075-T6

Secondary Stringers

Segment 12(1) 7.45% chord spacing Custom Aluminum 7075-T6 Section

Segment 16 4.10% chord spacing Custom Aluminum 7075-T6 Section

Segment 45 4.10% chord spacing Custom Aluminum 7075-T6 Section

Segment 23 5.00% chord spacing Custom Aluminum 7075-T6 Section

Segment 34 5.00% chord spacing Custom Aluminum 7075-T6 Section

Skin Design

Segment 12(1) 0.09 in Aluminum 7075-T6

Segment 12(2) 0.04 in Aluminum 7075-T6

Segment 23 0.08 in Aluminum 2024-T3

Segment 34 0.08 in Aluminum 2024-T3

Segment 45 0.0275 in Aluminum 7075-T6

Segment 56 0.08 in Aluminum 7075-T6

Segment 16 0.08 in Aluminum 7075-T6

Rivet Spacing 1.5 in Universal Head

Fatigue Design

Segment 23 8928 cycles to recommended change (3:1 Safety Factor)

Aluminum 2024-T3, based on edge crack behavior

Segment 34 6852 cycles to recommended change (3:1 Safety Factor)

Aluminum 2024-T3, based on edge crack behavior

*Tables Reference: “Aircraft Wing Load Analysis Proyecto Final.xlsx” (“Design Summary Section Details” Sheet)

CONCLUSION

Final wing weight estimated at 288 lb.

The design complies with all design considerations.

The design complies to Federal requirements as in

FAR 23 Subpart C.

RECOMMENDATIONS

Consider including flaps and aileron analysis for

future revision.

Material reduction for rib analysis.

Design wing using Finite Element Analysis and

comparison with analytical solution.

Use of composite material for future revision.

Flutter analysis for future revision.

BIBLIOGRAPHY

“ADVANCED MECHANICS OF MATERIALS AND APPLIED ELASTICITY ,“ Fifth Edition 2012, Ansel C. Ugural & Saul K. Fenster

“Aerodynamics Aeronautics and Flight Mechanics,” Second Edition 1995, Mc CORMICK

“Publications in Areonautical Science,” 1956, Khun

“THE SCIENCE AND ENGINEERING OF MATERIALS,” Fifth Edition 2008, Askeland & Phulé

“Conocimientos del AVION,” 2004, Antonio Oñate

“Theory of Wing Sections,” 1959, Abott & Von Doenhoff

“Weight-Strength Analysis of Aircraft Structures,” Second Edition 1960, Shanley

“Aircraft Structures,” 2011, D. J. Peery

“Steel Construction Manual,” Thirteenth Edition 2006, A.I.S.C.

“Aircraft Design A Conceptual Approach,” Fifth Edition 2012, D. P. Raymer

“AIRFRAME STRESS ANALYSIS AND SIZING,” Third Edition 2011, M. C. Niu

“Effect of Stress Ratio on Fatigue-Crack Growth in 7075-T6 and 2024-T3 Aluminum-Alloy Specimens,” 1969, NASA Technical Note Michael Hudson

eCFR-Code of Federal Regulations Volume 14 – FAR 23 Subpart C, 2013, FAA

Aerospace Structures ME 6300 Course Material, 2014, Dr. Hector Rodríguez