Fuselage Design

1. Airframe Design and
Construction
Part 2 – Fuselage Structural Design
Instructor: Dr Mohamed Elfarran
Aerospace Engineering Department
Cairo University
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Lecture 2.1: Intro

2. ACE 402 Road Map
• 1: Aircraft loads
• 2 : Section Properties Review
• 3: Bending Stresses
• 4: Column/Thin Sheets Stability (
buckling)
• 5: Crippling Strength
• 6: Sheet Effectiveness And Inter-
rivet Buckling
• 7: Stringers Failing Strength
• 8: Wing Stress Analysis
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3. Area Effective Iterative Method
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Failure Load DEPENDS Radius Of Gyration 𝜌
Radius Of Gyration 𝜌 DEPENDS Effective Width.
Effective Width DEPENDS Failure Stress
𝜌 =
𝐼
𝐴
?!!!!!!!!! 

4. Area Effective Iterative Method 2
• Bruhn Iterative Method Steps:
1. Calculate Crippling Strength ( Lec 5) as
Standalone Column
2. Get Effective width Wo based on S1
3. Get ρ
4. Get Fc from Johnson-Euler Equation:
5. Calculate W based on Fc
6. If d(W-Wo) > 10%, then repeat
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𝜌 =
𝐼
𝐴

5. Critical Stress Summary
1. Crippling stress is the failing stress of the corner stringers in
compression side. (Fcs)
2. Column failing stress is the failing stress of middle stringers in
compression side. (Fc)
3. • Ultimate stress is the failing stress of the stringers in the tension
side.
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6. Fuselage Structure
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7. Loads acting on fuselage
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8. Fuselage Structure
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9. Fuselage Structure
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10. Fuselage Crippling
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11. Fuselage Structure
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12. fuselage load-bearing members
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13. Section properties of thin sheets
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14. Circular arc section
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15. Example 1 – Circular fuselage
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16. Example 2 – Idealized Circular Fuselage
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17. Example 2 – Idealized Circular Fuselage
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18. Example 2 – Idealized Circular Fuselage
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19. Example 2 – Idealized
Circular Fuselage
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20. Wing Stress Analysis
Ref C7
What Next ……?!!!
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Assignments:
All Problems in C7