Home-made hail shields

[Darren Addy]

Originally posted by Greg Stumpf
Just the fact that you built a hail guard says you had intended to be in a situation like this.

That is quite a leap of logic. I find that imputing motives to others can be tricky business, even with the power of seeming certain. I can't speak to anyone else's intentions, but I'm a newbie and I'm quite sure that it is possible for me to drive myself into hail without knowing what the heck I'm even doing. Intending to do it would be a step up for me, since it would imply that I knew enough to accomplish the feat.

Since most chasers shoot video through their windshield, (not to mention how handy it is to see through for other purposes), I think it is prudent to give (at least) the windshield extra protection, though I can see why one might want to extend it to all windows, if possible.

To say that somebody builds a hail shield because they intend to be in a situation like that, is the same as saying that a Law Enforcement officer wears a Kevlar vest because they intend to be shot at. That's just plain silly. We chase storms that often shoot hail. How is it not prudent to be prepared for the unexpected?

Darren Addy
Kearney, NE

 

[Dave Lewison]

Despite my apparently inaccurate wording on my web page, we truly did not build this thing to sample hail cores. It was an insurance policy, pure and simple. It was built with the purpose of deflecting that one rogue baseball in otherwise smaller hail. Or just in case the core overtakes you before you're able to escape... Or if the road options just don't leave you a choice. We've all been in situations like these before. As Shane puts it, "SH*T HAPPENS". And THAT is what the guard was designed for.

Besides, I thought RJ built his vehicle as part of a hail research project he's doing, so he WANTS to sample hail cores. Although, I don't remember if he has his side glass protected. His windshield guard is a decent design, but I don't like that you can't really drive with it deployed. And since most of the time you won't have the opportunity to jump out and deploy a shield, I opted for a design that could be used while driving. My design was inspired by Eric Nguyen who had a similar rigid design on his van. I basically just added the fold-back option to mine.

The guard actually sticks out further than in the drawing...about 10" from the bottom center of the windshield. Any more than that, and you start losing visibility of storms, not to mention stop lights, etc. It was designed with roughly a 30-degree (from vertical) hail impact angle in mind. If hail's hitting at 45 degrees, then it's being blown sideways at over 100mph lateral speed, in which case you're probably screwed for other reasons! :lol:

 

[Greg Stumpf]

Originally posted by Darren Addy+--><div class='quotetop'>QUOTE(Darren Addy)</div>

Originally posted by Greg Stumpf+--><div class='quotetop'>QUOTE(Greg Stumpf)

Just the fact that you built a hail guard says you had intended to be in a situation like this. [/b]

That is quite a leap of logic.[/b]

I don't think it was that much of a leap, considering the statement that was on Dave's Web page. However, as you can see, he's already clarified that for us.

<!--QuoteBegin-Dave Lewison@
Besides, I thought RJ built his vehicle as part of a hail research project he's doing, so he WANTS to sample hail cores. Although, I don't remember if he has his side glass protected. His windshield guard is a decent design, but I don't like that you can't really drive with it deployed.

R. J. Evans was, AFAIK, the first mainstream chaser to have built a hail guard, and his intent was clear - to sample gorilla hail (you can ask him), along with other meteorological info via his live streaming mesonet data. And yes, he deploys his cage while stationary, and lets the hail cores move over him. His side and back glass is not protected (although this may change in the future).

<!--QuoteBegin-Dave L. also
The guard actually sticks out further than in the drawing...about 10\" from the bottom center of the windshield. Any more than that, and you start losing visibility of storms, not to mention stop lights, etc. It was designed with roughly a 30-degree (from vertical) hail impact angle in mind. If hail's hitting at 45 degrees, then it's being blown sideways at over 100mph lateral speed, in which case you're probably screwed for other reasons![/quote]
But if you intend to drive with it deployed as you say, you have to add the speed of the vehicle, and you might get impacts from a greater than 30 degree angle.

Also, wind speed isn't the only factor for hail trajectory. The shape of the stone, and sometimes its spin as it descends, can cause the stones to "glide" at angles off the vertical. Look up through your windsheild at falling smaller stones sometime and you you'll see the stones gliding in seemingly random directions (it's actually quite beautiful - like a "dance of the stones").

 

[Dave Lewison]

I understand how Greg could read into the comment on my webpage that we wanted to test the guard in some huge hail. Trust me, I didn't mean it to sound that way. In fact, if you watch the video on my May 12 page, you'll be able to tell that I REALLY did not want to be in that situation. ...rather, it was a byproduct of some decisions that left no escape.

Now more about the guard...the smaller stones will tend to come in at shallower angles because they fall slower and are more influenced by cross winds. Assuming turbulent flow around a sphere, a 4" hailstone will fall about 100mph. Assuming you're driving at 20mph into a 50mph RFD with softballs in it (WHY would anyone do this???), simple vector addition says that the stones would come in at 35-degrees from vertical. I figured this would be the absolute worst the guard would ever see.... By the same equation, a smaller golfball hailstone would fall about 55mph, and so could theoretically hit the glass if the truck was angled just wrong....but I was far less concerned about the smaller stones doing damage.

My biggest concern was hail sneaking around the sides of the guard if hit from that angle. I flared it out on the sides as much as I could, but there are limits...I didn't want a huge wing on the truck!

I wonder if there has been any research done on how hail impacts various materials. Sounds like a fascinating subject to me.

 

[cedwards]

I made a hail shiled back in 1996. I first used it in 97. It was made with 1/2"EMT frame and metal shelving as the cage. It folded up on the roof. When down, it snapped into the hood and allowed room for the windshield wipers to operate normally. I only used it the one year, because it seemd to repell hail more than I thought. I couldn't get in any big hail at all. It also was very anoying driving down the road. It created a lot of wind noise. I find it easier to just pay for a new windshield every now and then. This way I always have a nice clear view without lots of pitting that builds up after many thousands of miles.

 

[cedwards]

R. J. Evans was, AFAIK, the first mainstream chaser to have built a hail guard

NOT true. I built one long before he did. see my previous post.

 

[Shane Adams]

Originally posted by Greg Stumpf
it seems that you guys were probably one of the only vehicles that did the right thing on May 12

Not intending to start a debate on this, but just curious...what was, IYO, the right thing to do that day, in that situation? I've thought about this (just a while ago at work as a matter of fact, as the new guy was checking out the still-damaged windows on my car), and given everything that happened leading up to the development of the tornado, the only thing anyone could've done right (barring driving into gorilla hail, a tornado, or power pole-snapping RFD winds), would've ben not even being there to begin with.

The guy at work asked me about this encounter, and as Dave mentioned I say above, sometimes "sh*t happens." I don't place blame on anything, but if I were to, it would be the lack of roads. I can't say we shouldn't have been so close to the storm because I don;t spend $100 and drive 500 miles to run away from what I'm out there to chase. I can't say we made a mistake, because we did the bst we could with what we had to work with; my choices were (a) drive south and get smacked with RFD and consequently, power poles, (B) stay put and then drive south after the tornado crossed the road (uh oh, debris blocked the road, not an option after all), ©, turn east and drive right under a developing tornado (which did in fact begin north of the road and move south before anchoring), or (d) drive to the east road intersection, face east, and let the first tornado rope. Then, watch the new tornado develop very carefully, and mosey east behind it, staying well west of any "satellite" danger, and just hope like hell the hail doesn't take the windows.

I chose D, because if the worst happened, we knew it would be coming and were ready for it. Windows cost a few bills to replace, entire cars are a bit harder to replace (as in tornado debris). And people, well, those are irreplacable.

If you ever see the video, it's clear that we both know what's coming, but also know there isn't jack squat we can do about it, so we just hunkered down, kept the video rolling, and hoped for the best. Once the window exploded, I made the only defensive move I could at that point, and backed up a full quarter mile (keeping the already-smashed window face towards the hail onslaught) to get further away from the tornado/updraft center, as the further away you get from this area, the less-likley you'll have the largest stones.

I've replayed the event in my mind a thousand times, and I honestly don't think I'd do anything differently if given the chance. I like being close, but I looked up at that circulation and I didn't want any part of being underneath it. Driving east was probably another option that could;ve provided safe haven from the hail, but IMO, the tornado was a definite threat; the gorilla hail was a possibility...and I'll take a possible threat over a definite one every time.

But man, what a great piece of video it yielded :wink:

 

[Dave Lewison]

We chose Shane's option "B", and well...that didn't exactly work out well either. I tell ya, nothing's more sickening than the sound of powerlines scraping past your ham antennas. I desperately wanted to get east. I remember flying by that roadsign for the east road that most people took, and thinking to myself "oops". But having seen Charles' video, I'm not sure I would have wanted to be on that road after all. That second tornado was VERY close! Although it looks like the hail there was slightly smaller....not that it matters much. A 3" stone might as well be 6" where glass is concerned!

BTW, does anyone know if that "second tornado" was in fact from a seperate meso/circulation, or was it the remains of the first circulation that just re-intensified? I can't say since we didn't take that road, but it sure looks like it.

 

[cedwards]

I chose to go east. I did not drive under the circulation. I went north of the main circulation. It was to my SE when it really got going. Then the missiles started coming down. We wanted to go east on the road and go north of the tornado, but the tornado had other plans. It had a slight northward component to its motion. I figured the bigger hail would be behind us, so we opted to stay close up to the tornado. As it turned out, that did minimize our damage. In two vehicles, we lost two windshields and one side window. It we would have been farther back where Dave was, we may have lost a lot more. I didn't have a hail shield, but I did find a cheep place to get the glass repaired. The biggest downfall was we were down the next day making the repairs. Only one windshield was fixed at the time since the other was not too bad. We finished the second one off with a stray baseball on May 31.

 

[Shane Adams]

Originally posted by Dave Lewison

BTW, does anyone know if that \"second tornado\" was in fact from a seperate meso/circulation, or was it the remains of the first circulation that just re-intensified? I can't say since we didn't take that road, but it sure looks like it.

IMO it was a new circulation, that formed very near the first one. This evolution/cycle reminded me a lot of the 5-5-02 Happy, TX "hand-off" between the two tornadoes that day. Seemed the original circulation slowly fizzled as the new one rapidly intensified very near (just east) of it.

 

[Rob_Davis]

Originally posted by cedwards
I didn't have a hail shield, but I did find a cheep place to get the glass repaired. The biggest downfall was we were down the next day making the repairs. Only one windshield was fixed at the time since the other was not too bad.

That is pretty much why I have concluded that the only glass worth caging is the windshield. If you lose a side or rear window, you can cover it and keep on going. But if you lose a windshield, you are out of action until it can be fixed.