How to determine force from wind on flags

[spciesla]

Been windy the last couple of days and I left my flag up until mother nature decided it needed to be on the ground. I have a flag bracket that was secured to a facia board with three screws. It appears that the force from the wind on the flag caused the screws to loosen/backout, which then allowed the bracket to move more, and eventually pull out the screws completely. That got me thinking, how can we model/account for the forces on a flag from the wind. What kind of boundary conditions can we apply to the 3 free sides and even the attachment side (2 rings with grommets)? Is this done analytically or completely empirical? Thoughts?

 

[Celt83]

Refer to FP 1001-07 put out by The National Association of Architectural Metal Manufacturers (NAAMM)

 

[rb1957]

more a vibration thing ? use lock nuts.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[dik]

I prefer LOctite Red to lock nuts... more positive.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[spciesla]

I appreciate the recommendations for preventing this happening again, although my solution will probably be take the flag down when it's windy. I was more interested in the engineering analysis of the situation, out of curiousity.

 

[LittleInch]

See also this thread which quotes the same code for flag poles.

A little bit of googling found this

Guidance seems to be max 30 mph / gale force 6

These guys might already know...

https://libertyflags.com/blogs/default-blog/blog-wind-its-effect-on-flags-and-flagpoles

And right here on this site from one of the earliest posts (no 1001 !!)

https://www.eng-tips.com/viewthread.cfm?qid=1001

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