1. AAE 556 Aeroelasticity Lecture 9
Differential equation models
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2. Goal – Construct torsional equilibrium equations for a diff. eq. model
Define stability conditions for idealizations with differential equations
Reading - Section 2.19
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3. The aerodynamics modelx
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4. The distributed torsional loads-including weightx
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5. The structural model with FBD
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6. The equation of torsional equilibrium
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The math problem
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8. The divergence problemx
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9. The divergence problemx
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10. The stability determinant
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The eigenvalues
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12. The eigenvector (mode shape)
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13. Stiffness? Place a torque To at the ¾ span position
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14. Typical section stiffness
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15. Typical section stiffness
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16. Problems in high speed flight
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17. Increasing Tu-144 SST elevon effectiveness - a classic MDO problem
Subsonic vs. supersonic deformation
Control effectiveness
Fuel management?
Larger engine?
Canards?
Stiffening?
Problem - trim drag is too high - suggest a fix
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Loading conditions
Subsonic cruise
take-off
elevon element IV loading
elevon element II loading
special loading
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Solution-add weight
Thicken skin panels 1 2 3 4
Elevons
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