4 ms·

It's a good idea to solve the problem instead of what the article describes, but there's an issue with canopies. The types of storms that produce hail, usually

It's a good idea to solve the problem instead of what the article describes, but there's an issue with canopies. The types of storms that produce hail, usually supercellular, often have damaging straight-line winds. While out storm chasing, I've seen several gas station canopies collapse from strong winds - I'm struggling to think of a canopy solution that wouldn't have the risk of collapse.

clarry 7y ago
I've also seen a lot of bad construction that catches on wind like a sail. It doesn't have to be built this way, however. A canopy that protects from hail coming from above can still have lots and lots of holes that lets wind go through.
- lllr_finger 7y ago
  Wind driven hail traveling nearly sideways is common unfortunately. I'm not sure what angle of protection would be the best compromise, but I do know a copy above would not afford 100% protection.
  - clarry 7y ago
    Hmm, I don't think I have experience with such hail. In my experience, the bigger they are and the harder they hit, the more vertical their trajectory. But my area isn't particularly prone to hailstorms.
    - lllr_finger 7y ago
      Allow me to nerd out a little, since my other love besides development is severe weather. The forward flank downdraft or rear inflow jet of a linear convective system/bow echo can see winds of 50mph+ rather commonly. The more interesting part IMO, is the rear flank downdraft, because it is closely related to tornadogenesis and can also have winds up to 100mph. The RFD is co-located with the hail core in a supercell, so some hail will get caught up in this wind that exists even when there isn't a tornado. Now terminal velocity of your average baseball-sized hail is roughly 100mph, but you can imagine with 100mph horizontal winds that there can be a strong non-vertical component to the hail in certain portions of the storm. I've personally been hit by smaller 1-2" hail that is traveling nearly horizontal, and I've seen evidence of larger hail impacting at the same angle. It's a safe assumption that the larger the hail is the more damaging it is, but not all hail is created equal! Depending on how accretion happens and the warmth of the atmosphere, you can have very hard 1" hail that damages cars, and very soft 2.5" hail that doesn't damage cars. My personal rule of thumb is that you need to be wary of anything 1.75"/golf ball or larger.
    - AaronM 7y ago
      Having lived in tornado alley, I've seen softball sized hail completely punch through a residential roof (shingles, and plywood) and then punch through the sheetrock in the ceiling.
herendin2 7y ago
Maybe a soft one-inch foam canopy secured closely to the vehicle so wind can't catch it, with couple straps under the vehicle chassis? Could that work? Could it be put in place in time? Alright, that's not really a canopy, more like a shield or body armor. </edited>
- dsfyu404ed 7y ago
  Just armchair engineering here: It wouldn't be hard to make some thick foam mats with straps sewn to them that can be rolled out and fastened to cars in under a minute each. Maybe toss in a couple plastic strips to make it unroll itself like the reverse of a slap koozie. Weather forecasting is pretty good. It's not like you don't have decent warning. You can cover everything out back and leave the cars that are on display out front uncovered until the last minute. Tossing a mat over a high roof van or large pickup wouldn't be easy but the hordes of crossovers could be well protected.
  - herendin2 7y ago
    Alright! StormShield, YC S20, is officially launched! First round starts at $20m! OK, maybe it does almost sound feasible, but I wonder what someone with outdoor car dealership experience would say? Is this a practical idea? How often do you need to unroll those mats?
    - kaibee 7y ago
      Where are you storing the mats also? I can't imagine that they'd be small, even rolled up.
      - herendin2 7y ago
        Right, those mats wouldn't be small. They would need lots of storage area. Maybe a few be stored, rolled up, under vehicles at the back of the lot that are less likely to be moved? And the rest could be stored indoors. They shouldn't be heavy, so maybe they can be stashed in the ceiling, or somewhere high up out of sight?
dbatten 7y ago
Then you end up insuring your canopies against wind damage... And your cars against the possibility of canopies falling on them. And still insuring your cars against hail in the event that the canopy blows off, or the hail comes down at an angle and isn't fully blocked by the canopy, or whatever. Also, I'm imagining canopies getting in the way of 1) making inventory highly visible (both from the road and other parts of the lot) and 2) making it harder to pack cars really close together because you have to deal with all the canopy supports. Just musings...
MisterTea 7y ago
> I'm struggling to think of a canopy solution that wouldn't have the risk of collapse. A canopy that isn't solid and allows the wind to pass through. A mesh or screen should do the job. The opening size can also be larger so perhaps even netting with openings upward of a few cm could work.

clarry 7y ago

I've also seen a lot of bad construction that catches on wind like a sail. It doesn't have to be built this way, however. A canopy that protects from hail coming from above can still have lots and lots of holes that lets wind go through.

lllr_finger 7y ago
Wind driven hail traveling nearly sideways is common unfortunately. I'm not sure what angle of protection would be the best compromise, but I do know a copy above would not afford 100% protection.
- clarry 7y ago
  Hmm, I don't think I have experience with such hail. In my experience, the bigger they are and the harder they hit, the more vertical their trajectory. But my area isn't particularly prone to hailstorms.
  - lllr_finger 7y ago
    Allow me to nerd out a little, since my other love besides development is severe weather. The forward flank downdraft or rear inflow jet of a linear convective system/bow echo can see winds of 50mph+ rather commonly. The more interesting part IMO, is the rear flank downdraft, because it is closely related to tornadogenesis and can also have winds up to 100mph. The RFD is co-located with the hail core in a supercell, so some hail will get caught up in this wind that exists even when there isn't a tornado. Now terminal velocity of your average baseball-sized hail is roughly 100mph, but you can imagine with 100mph horizontal winds that there can be a strong non-vertical component to the hail in certain portions of the storm. I've personally been hit by smaller 1-2" hail that is traveling nearly horizontal, and I've seen evidence of larger hail impacting at the same angle. It's a safe assumption that the larger the hail is the more damaging it is, but not all hail is created equal! Depending on how accretion happens and the warmth of the atmosphere, you can have very hard 1" hail that damages cars, and very soft 2.5" hail that doesn't damage cars. My personal rule of thumb is that you need to be wary of anything 1.75"/golf ball or larger.
  - AaronM 7y ago
    Having lived in tornado alley, I've seen softball sized hail completely punch through a residential roof (shingles, and plywood) and then punch through the sheetrock in the ceiling.

herendin2 7y ago

Maybe a soft one-inch foam canopy secured closely to the vehicle so wind can't catch it, with couple straps under the vehicle chassis? Could that work? Could it be put in place in time? Alright, that's not really a canopy, more like a shield or body armor. </edited>

dsfyu404ed 7y ago
Just armchair engineering here: It wouldn't be hard to make some thick foam mats with straps sewn to them that can be rolled out and fastened to cars in under a minute each. Maybe toss in a couple plastic strips to make it unroll itself like the reverse of a slap koozie. Weather forecasting is pretty good. It's not like you don't have decent warning. You can cover everything out back and leave the cars that are on display out front uncovered until the last minute. Tossing a mat over a high roof van or large pickup wouldn't be easy but the hordes of crossovers could be well protected.
- herendin2 7y ago
  Alright! StormShield, YC S20, is officially launched! First round starts at $20m! OK, maybe it does almost sound feasible, but I wonder what someone with outdoor car dealership experience would say? Is this a practical idea? How often do you need to unroll those mats?
  - kaibee 7y ago
    Where are you storing the mats also? I can't imagine that they'd be small, even rolled up.
    - herendin2 7y ago
      Right, those mats wouldn't be small. They would need lots of storage area. Maybe a few be stored, rolled up, under vehicles at the back of the lot that are less likely to be moved? And the rest could be stored indoors. They shouldn't be heavy, so maybe they can be stashed in the ceiling, or somewhere high up out of sight?

dbatten 7y ago

Then you end up insuring your canopies against wind damage... And your cars against the possibility of canopies falling on them. And still insuring your cars against hail in the event that the canopy blows off, or the hail comes down at an angle and isn't fully blocked by the canopy, or whatever. Also, I'm imagining canopies getting in the way of 1) making inventory highly visible (both from the road and other parts of the lot) and 2) making it harder to pack cars really close together because you have to deal with all the canopy supports. Just musings...

MisterTea 7y ago

> I'm struggling to think of a canopy solution that wouldn't have the risk of collapse. A canopy that isn't solid and allows the wind to pass through. A mesh or screen should do the job. The opening size can also be larger so perhaps even netting with openings upward of a few cm could work.