Roof torn off in high winds

[jadmt]

@Wildeshawn witnessed this happen In Missoula yesterday

 

[roving1]

For reference you may wish to read Hydrodynamica by Bernoulli.

The faster a fluid flows the less pressure is created so in this case the fast moving fluid (air) created less pressure on the outside and lifted the top enough to break the clamps and counter the force of gravity.

I doubt it. The roofs of some commercial vehicles are wafer thin fiberglass with minimal bracing you can't even walk on. If negative pressure was the issue these roofs would get sucked off pretty regularly and they don't.

I have also transported vehicles with damaged roofs back and forth across Wyoming in huge winds with large ripped shreds of fiberglass held down with not much tape that would have taken little negative pressure to cause to fail and the temp patches have held. I humbly don't think those are the forces at work here.

I think the wind is getting past the seal and pressuring the interior much like a tire beading device.

 

[roving1]

That is not a good example since pressure to seat a bead is maybe 50 PSI above our standard atmospheric pressure of 14.7 PSI. Now I do agree that forcing a some additional pressure into the FWC might provide enough to break it free but that would only work in a sealed system. Your theory relies on an elaborate system where it is sealed enough to permit the pressure to build inside yet still open enough to permit the pressure to come in. That is complex and unlikely.

Except that is exactly what would happen when a gust gets past the seals, or compresses the seals enough to unlock a latch and cause the others to fail, or flutters on the seals and shock overloads the fasteners. The localized pressure in these areas is extremely high not low.

I'm not 100% sure negative or positive pressure delta is enough to do the job here either way. But the notion that a negative pressure delta of low atmospheric pressure vs 14.7 is a greater force than 100-140MPH getting inside vs 14.7 doesn't seem likely to me.

Show me data and the math to prove the force on a camper designed for people to sleep in without asphyxiating can suck a roof off at speed and I will believe it.

Otherwise I will have to go with a million miles of experience of dragging cubes and various cargo though the air at often ludicrous combined wind speeds and what is likely to cause damage and what will survive.

 

[craig333]

This is interesting. I and all the others I've talked to have never had a latch unlatch. Other latch issues yes but not unlatching. Failure to latch? Not at all uncommon yet it doesn't lead to roof failure. A bit embarrassing if the roof suddenly pops up but it doesn't lead to damage and especially not catastrophic failure.