Fuselage design

[Jason2000]

Hi

Just wondering why the different aircraft manufacturers use such different designs of stringers in their fuselage structures, ie Airbus and Boeing. Airbus ones are more like an S shape while Boeing use a J shape one. Which is better? Is it something to do with their Second Moments of Area? Just curious as to which would be used on a slightly faster aircraft such as the Sonic Cruiser.

Also, what determines how far apart the frames are spaced along the fuselage in a typical commercial airline design. How would area ruling be incorporated?

Cheers

Jason

[Volume]

In fact you can find even more shapes of stringers at other manufacturers like Lockheed, Dornier, Saab, de Havilland or Douglas : U-shape, I-shape T-shape, H-Shape, C-Shape and Hat sections. There are quite different pros and cons for each design.

Aspects for choosing the one or the other design are :
- Accesability for automatic riveting by robots
- Buckling resistance to allow the actual frame spacing
- Corrosion prevention by not allowing water to be trapped in the cavity between skin and stringers
- Frame-stringer-intersection design, need of having plane flanges to attach clips or cleats to the stringers
- Placing the area center of the stringer in the plane of the rivet line perpendiular to the fuselage skin (to prevent the stringers from twisting if the fuselage is pressurized which might lead to cracks in the sealing and therefor corrosion problems)
- Repair provisions, can a doubler be added without problems ?
- Inspectability for cracks

It´s hard to explain about all this stuff without making sketches or drawings