Metallic sandwich structure having small bend radius

1. An acoustic-attenuating wall panel, comprising:

a radiused portion of an inner wall panel of a nacelle;

the radiused portion including an airflow surface having a concave configuration being exposed to an airflow; and

the radiused portion comprising an acoustic attenuating section and formed as a honeycomb sandwich structure having a honeycomb core sandwiched between a pair of face sheets;

the honeycomb core in the radiused portion has a cell width that is the same as the cell width of the honeycomb core in at least one of the following portions of the inner wall panel: a barrel portion, an upper bifurcation, a lower bifurcation.

2. The acoustic-attenuating wall panel of claim 1 wherein:

the honeycomb sandwich structure is a metallic honeycomb sandwich structure.

3. The acoustic-attenuating wall panel of claim 1 wherein:

the honeycomb core has a core thickness; and

the airflow surface is provided by an airflow face sheet having an inner radius; and

the inner radius being formed at an inner radius/core thickness ratio of no less than approximately 2:1.

4. The acoustic-attenuating wall panel of claim 3 wherein:

the inner radius is no less than approximately 2.0 inches.

5. An inner wall panel, comprising:

a semi-circular barrel portion having circumferentially opposite ends;

an upper bifurcation wall portion and a lower bifurcation wall portion extending radially outwardly from the circumferentially opposite ends of the barrel portion;

an upper radiused portion and a lower radiused portion joining the respective upper and lower bifurcation wall portion to the circumferentially opposite ends of the barrel portion; and

at least one of the upper and lower radiused portions being formed as a honeycomb sandwich structure having a honeycomb core sandwiched between a pair of face sheets, the honeycomb core in the radiused portion has a cell width that is the same as the cell width of the honeycomb core in at least one of the following portions of the inner wall panel: a barrel portion, an upper bifurcation, a lower bifurcation; and

the inner wall panel comprising a metallic, one-piece, unitary structure.

6. The inner wall panel of claim 5 wherein:

the inner wall panel forms part of a nacelle of a gas turbine engine.

7. The inner wall panel of claim 5 wherein:

the upper and lower radiused portion each include an airflow surface having a concave configuration being exposed to an airflow through a nacelle.

8. The inner wall panel of claim 5 wherein:

at least one of the upper and lower radiused portions comprises an acoustic attenuating section.

9. The inner wall panel of claim 5 wherein:

both of the upper and lower radiused portions comprise a honeycomb sandwich structure.

10. An aircraft, comprising:

a nacelle connected to a turbine engine, the nacelle having an inner wall panel positioned along a duct airflow path of an airflow;

the inner wall panel having a radiused portion including an airflow surface having a concave configuration being exposed to an airflow;

the radiused portion comprising an acoustic attenuating section and formed as a honeycomb sandwich structure having a core sandwiched between a pair of face sheets; and

the honeycomb core in the radiused portion has a cell width that is the same as the cell width of the honeycomb core in at least one of the following portions of the inner wall panel: a barrel portion, an upper bifurcation, a lower bifurcation.

11. The aircraft of claim 10 wherein:

the the honeycomb sandwich structure is a metallic honeycomb sandwich structure.

12. The aircraft of claim 10 wherein:

at least one of the face sheets comprises an airflow face sheet forming an airflow surface exposed to the airflow; and

at least a portion of the airflow face sheet having a plurality of holes fluidly coupling the cells to the airflow.

13. The aircraft of claim 11 wherein:

the honeycomb core has a core thickness;

the airflow surface is provided by an airflow face sheet having an inner radius; and

the inner radius being formed at an inner radius/core thickness ratio of no less than approximately 2:1.

14. The aircraft of claim 13 wherein:

the inner radius is no less than approximately 2.0 inches.

15. The aircraft of claim 11 wherein:

the nacelle includes a bifurcated fan duct defined by the inner wall panel and an outer wall, the inner wall panel extending between generally radially opposite sides of the outer wall;

the inner wall panel comprising a semi-circular barrel portion having an upper bifurcation wall portion and a lower bifurcation wall portion extending radially outwardly from circumferentially opposite ends of the barrel portion;

each one of the upper and lower bifurcation wall portions being joined to the barrel portion by a respective upper and lower radiused portion; and

the inner wall panel being formed as a one-piece, unitary structure.

16. A method of attenuating noise of a turbine engine, comprising the steps of:

passing an airflow along a concave airflow surface of a radiused portion of an inner wall panel within a nacelle, the radiused portion comprising a honeycomb sandwich structure including a honeycomb core sandwiched between a pair of face sheets and having a plurality of cells, the honeycomb core in the radiused portion has a cell width that is the same as the cell width of the honeycomb core in at least one of the following portions of the inner wall panel: a barrel portion, an upper bifurcation, a lower bifurcation;

fluidly coupling the cells to the airflow through a plurality of holes formed in an airflow face sheet of the honeycomb sandwich structure; and

absorbing acoustic energy in the airflow fluidly coupled to the cells.

17. The method of claim 16 further comprising the steps of:

passing a portion of the airflow through the holes such that the airflow enters the cells; and

absorbing acoustic energy in response to the airflow entering the cells.

18. The method of claim 16 wherein:

the honeycomb sandwich structure is a metallic honeycomb sandwich structure.

19. The method of claim 16 wherein the airflow face sheet has an inner radius, the honeycomb core having a core thickness, the method further comprising the step of:

providing the airflow face sheet with an inner radius having an inner radius/core thickness ratio of no less than approximately 2:1.

20. The method of claim 16 further comprising the step of:

providing the airflow face sheet with an inner radius at no less than approximately 2.0 inches.