effect of ribs position on aerodynamic behavior

[dankoonFANTOMAS]

Hello everyone,

I was wondering what is the effect of ribs position on a wing on the aerodynamic behavior and especially on the aeroelastic behavior. Does the position of ribs can change the dynamic behavior for a flutter phenomena for example.

I am not an expert in aircraft design so I do not know how the space between ribs is calculated it's just a question that came to me while talking with a colleague.

Hope someone have a point on this topic.

Have a nice day

BR

Dankoon

 

[rb1957]

I'd've thought the main thing positioning ribs is column support for the upper stringers.

I guess there may be some affect on stiffness, I mean there'd probably be a difference if you went to the extreme (say rib spacing = b/2), but between normal rib spacings I'd've thought that'd be small.

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[IRstuff]

Seems irrelevant, as rib positions are not random nor variable. The designer determines the number of ribs and stringers to achieve the desired stiffness/weight requirements of the design. So, yes, they do have an impact, but that's by design, not by accident.

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[berkshire]

It should be noted that if there are insufficient ribs in a particular design, the wing skins tend to " oilcan" which momentarily changes the profile.
The plane then sounds like a flying collection of trash cans.
B.E.

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[KENAT]

I was thinking along the same lines as berkshire.

In most cases this oil canning would probably just cause a slight increase in drag and change in properties of the aerofoil like stall angle, pitch moment... probably relatively inconsequential.

However, depending what surface it is on and where in the flight profile the A/C is it could conceivably be catastrophic.

Also could lead to fatigue issues.

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[mohr]

Hi...the canning probably affects the structural stability and rigidity....allowing more deformation, and the elastic deformation is not a good friend of aeroelasticity phenomenon.

Cheers