Chris Sokol
EF5
This section has been created to replace the thread in Weather and Chasing, and is meant to be a discussion on design and theory of hail guards. Please stay on this topic.
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Hail Guard Design
- Thread starter Chris Sokol
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Rob_Davis
Thanks, Chris. I was afraid a potentially productive thread was about to go down the toilet.
Allow me to resubmit the query I had in the original thread for just a little more input:
I have a couple of questions for those of you with multiple encounters with hail while chasing:
1. How long do you usually have between the time you know you're going to be hit and the time it actually hits you?
2. What factors determine how much warning time you have?
I ask because hail protection obviously needs deployment time. If you are intentionally core punching, then you have that guaranteed prep time before you enter. But if you simply end up in the path of softballs through miscalculation (heading the wrong direction) or ignorance (no up to date radar images or radio reports), it seems that you could be taken by surprise and have no chance to deploy your protection before you are hit. In the real world, how often does this happen?
I have some ideas for vehicular hail protection, but they all involve the need for safe deployment time BEFORE you are hit.
And THANK YOU to Karen for posting that video link! I was actually quite unaware of the potential for such rogue strikes!Dave Lewison
EF1
Rob, would you care to share your ideas? I feel a little better about inquiring on this now, as it's more related to the thread topic. I'm still looking at ideas to cover the rear sides and back glass for next season. Trust me...when you're cooped up in the back of a vehicle trying to shoot video through thick black wire mesh, it can get pretty frustrating! I want CLEAR visibility next time!
BTW, I know the chaser who shot the video Karen posted. That's of the Mulvane KS tornado/hail on 6/12/04. It truly was a rogue tennis ball that did it. The interesting part is that he DID have a hail shield on that window. It was a Lexan sheet, but I'm guessing it wasn't spaced far enough away from the glass, so the hail flexed the Lexan enough to impact the glass and shatter it. Incidentally, he told me that even though the window broke, the Lexan held, and prevented rain from streaming into the van...a nice side benefit.Rob_Davis
Sure, although you may be sorry you asked! :lol: I have had a couple of run-ins with big hail over the years, although not while chasing, which is why I need specific info on the threat faced while chasing.
Anyhow, when the softball hail decimated Fort Worth back in May of '92 or '93 (?), I got caught up in it. I knew from Skywarn that it was headed our way, so I had just a couple of minutes to prepare. All I had with me was the two summer-weight sleeping bags in the back of my Cherokee. I put one across the windshield and one across the hood, pointed the vehicle into the storm and hoped for the best. Amazingly, there was NO damage under the sleeping bags, except for a couple of VERY minor hood dents which were barely noticeable. The windshield was untouched. Conversely, the unprotected portion of the roof was beaten to hell and the ham antenna was smashed.
That experience got me to thinking about the physics of the whole thing. Just like a ballistic vest, the key to success is not necessarily in deflecting the projectile like steel, but in dissipating the kinetic energy from it like Kevlar, by spreading it over a greater surface area. So, on the vehicle surfaces or the windshield, you could do the job as easily as bungee cording a couple of those thin foam backpacking pads (available at any army surplus for $5 to $10 bucks) across them and not really need any kind of cage or shield. They would be more than adequate for side and rear windows, although you would probably want to double layer it over a sunroof.
Of course, the problem arises when one is caught by surprise and cannot safely get out of the vehicle for the 30 to 45 seconds it would take to secure these barriers across the vehicle. Not to mention that they obscure your vision so you can no longer drive or photograph the action. Obviously, the ghetto approach is effective, but presents unacceptable problems of its own.
I have only seen a very few examples of people's attempts to cage their vehicles so far (although I would love to see others post pics of theirs here!). What I picture is a little different. Instead of overhanging the windshield from the roof, I would approach it from the opposite direction. Remember the old-skool Jeeps that had the fold-down windshields? My idea centers around the same concept. A steel or aluminum frame that holds a rectangle of expanded steel and lays across the proximal half of the hood, then swivels up from hood/fender groove mounted hinges to cover the windshield. Yeah, it would seriously screw with your camera's auto-focus, but you could still see through it and be assured of keeping your windshield intact.
Alternatively, you could use 1/4 inch Lexan in place of the expanded steel. It is more expensive, but would provide better visibility and would probably hold just fine with the addition of one vertical support in the center of the frame. Of course, if you run into a full barrage, it is going to get so scraped and chipped that you're going to want to replace it before your next chase, which would cost at least as much as a new windshield. In the case of Lexan, it may not save you any money in the long run, but it will keep your video rolling, as well as keeping you from having to end your chase early while you wait three days in One Horse, Kansas for your new windshield to arrive.
As for the side and rear windows, I tend to agree with the earlier suggestion that it is cheaper and easier to just replace them when necessary than to try and cage them. If you turn into the storm, they shouldn't be receiving many direct hits anyhow. And unlike a windshield, if they break, a plastic bag and duct tape will get you home just fine. Unless you are building a full-on "Tornado Attack Vehicle," the threat vs. cost analysis just doesn't justify going that crazy with it. Just like a soldier puts kevlar only over the vital organs, it makes sense for us to do likewise and only worry about the glass that you could not continue without. And, unlike RJ, I don't have any moral problems with using my insurance to pay for hail damage. :roll: After all, they didn't have any moral problem with charging me for coverage all those years I ended up not needing it.
If I do anything about side and back windows, it will just be to have that mylar blast film applied to keep them in place when broken. That will keep the hail from penetrating, and a cover in place to keep the rain out. Plus, the film won't present problems for your photography.
Well, if you know the guy then I feel a little better about the authenticity of that video! I wasn't going to mention it, but after watching that clip a few times I began to wonder if it wasn't a hoax. First, there is a clicking sound just before the crash that sounds exactly like a tape player being turned on. Second, the glass breaking sound is a little too glassy and sounds more like plate glass than tempered safety glass. Third, there is ONLY the sound of glass breaking and not the huge BOOM you would expect from such a hit, especially if it hit the Lexan first. Fourth, the reaction of the cameraman is unexpectedly smooth and un-startled, which is hard to imagine. Fifth, his vocal comment is extremely delayed. I think most people would have let loose with the F-bomb within the first millisecond, not three full seconds later. Sixth, and even more strange, the other occupant -- presumably the owner of the vehicle! -- didn't say anything at all! :shock:
Regardless, it's an awesome video!
Jason_Politte
EF2
Well, if it's a hoax, it was a $450 hoax. That's my video that was posted so allow me to clarify a few things.
First, that video clip is real with no alterations. Both Karen and Dave have seen that video first hand. I'm the one who shot the video, and I also own the vehicle that video was shot from.
Second, the Lexan was never designed to protect the windows from large hail. Last year, I bought a 2002 Dodge Caravan for a chase vehicle, and like most minivans, they have rather large side windows. Having those large side windows bothered me because I had in the past seen minivans with multiple windows shattered by wind-born debris on days such as 5/5/02 and 5/27/01, and that is the main reason I installed the Lexan. Plus, it allows me full visibility, and I'm not having to peer out of a cage. As that video clip illustrates and Dave mentioned, if Lexan is to be used for hail protection, it must be spaced away from the window.
I have no idea what that "clicking" sound is that you refer to. The event occurred more than a year ago, and I can only assume that I bumped into something in the vehicle while leaning forward to shoot up through the windshield.
Well, I don't know if you've ever heard safety glass break, but that's pretty much what it sounds like. I'm not sure why you'd expect some type of large "BOOM" from the Lexan being hit since the video was shot from inside the vehicle and the glass breaking would stand out much more than the Lexan being hit. Perhaps if I had been filming outside the vehicle, the Lexan being hit would've been the more prominent sound.
Regardless, the Lexan covered window was struck by a very large hail stone. With minimal spacing between the Lexan and the window, the Lexan was pushed in and contacted the window with enough force to shatter it, leaving a large hole punched through the window where the hail stone hit. The rest of the window, while shattered, was actually held in place by the attached Lexan, which allowed me to continue the chase basically unhindered.
As far as the Lexan goes, it was neither cracked nor significantly damaged in any way, and it's still being used today. However, there are some neat concentric compression rings that spread out from where the hail stone struck.
It's not too terribly smooth and unstartled. Take a look at the camera jerk at the time of impact, which was definitely lessened by steadyshot. Not being too sure what had just happened, I turned around to look at the shattered window before making the comment, hence the delayed reaction and camera moving around considerably.
Sixth, and even more strange, the other occupant -- presumably the owner of the vehicle! -- didn't say anything at all! :shock:
Regardless, it's an awesome video!
There was no other occupant in the vehicle besides myself. Anyway, I hope that clears up some of your questions regarding the authenticity, and I'm happy you enjoyed the video.
Oh, and one last thing, here's a photo of the Lexan the next day being used as a temporary window.
The shattered glass was removed the night before. If you look closely at the top center of the Lexan sheet, you can make out the concentric rings I previously referred to. And if anyone's interested in the rest of my images from that day, they can be found at:
http://www.onthefront.ws/jun1204.htm
Thanks,
JasonDave Lewison
EF1
Whoa wait...hold on there. That's one of the bigger misconceptions out there. Side glass can be every bit as expensive to replace and even moreso. Scott's rear side window on the XTerra cost $480. Chris' rear side on the Honda Element cost $900! Back in 2001 when I had my Ford Taurus broken into, the tiny little rear window sidepanel that the crook got in through cost me $700 to replace! It's not so much the actual value of the glass...it's how available it is that determines the cost. Windshields break far more commonly and so are easier to get and cheaper. Plus, side windows are not as impact rated as the windshield, and will be easier to break. In chase mode, angling the vehicle to avoid side strikes is very difficult. Especially in and near the RFD, where hailstones can be flying sideways at 80mph.
This is very similar to RJ's hail guard design. His hinges at the base of the windshield and can be flipped up to attach at locking clamps at the top of the windshield. However, it's made of coated expanded steel, and can't safely be driven while it's deployed. (at least, I wouldn't think so). Making it out of Lexan might solve that problem, but then you've got a 3x5 ft sail on your hood when it's not deployed and you're driving 80mph. That'd be worrisome to me.
This isn't a bad idea, but I think it'd take longer than 30-45 seconds to put on there securely. Not a choice I'd use while chasing, but certainly possible for folks at home with no available carport, and about 5 minutes of leadtime.
Hahah! He IS pretty smooth isn't he? That's because he's experienced. I think it's the way he says the F-bomb so matter-of-factly that makes it a classic chase video clip! I've showed that to many of my non-chaser friends and they all love it. You know it's a classic when it's funny outside our little chaser circle. It sounds pretty funny even when it's bleeped too!
Robbie Cox
EF2
I agree on not getting out of vehicle (helmet or not): lol:
Why not incorporate air actuator's and use lift arms to draw up Lexan to windshield ?It would not be very hard using the principal you suggest and you can then also use air operated locking clamps or something similar to unlock it to fold back into place. A small air compressor then can be mounted in engine compartment and possibly a storage tank to ease to function quickly. Just a thought but a very plausible idea.
Also most side windows are not tempered glass. So one could do like David drummond mentioned in his piece on building his new chase vehicle .and work out a deal with your local scrap yard and have replacement glass on hand. If they don't have it they can locate it, or replace what you have now with plexglass during chase season. :wink:John Diel
EF5
I like the lexan spacer idea for side windows. The windows on my camper shell are not the highestest quality. They arne't sheet glass, but they aren't windshield material either. I'm going to try and finangle an idea or two I've got rolling around in my head. As soon as I get the idea down on paper I'll post it here.Mike Sharp
Just an idea- If you are using Lexan on side windoes that you don't film out of, how about putting some of that large bubble packaging material between the lexan and the glass. It might just absorb the flexing .It will still let light through and also act as a slight security screen.John Diel
EF5
Mike
I was actaully thinking on those same lines but a little more asthetically. Make a mount that holds the lexan securely at 1 inch from the glass. Since I have split or sliding windows on the camper shell, I would cut the lexan to fit the existing glass, make a wood mount vertically at fore, aft and center. In the center of the "open' areas, I would have a round piece of closed cell foam (Large hot water pip insulation cut to 1.25 inch). This closed cell foam would reduce the amount of bow from the lexan when it gets hit and dissapate the force of the hit acting as a "cushion". Since the windows are 6 feet long by about 1.5 feet high, this 'should' work out fairly well and still keep the vehicle from looking like an armored personell carrier. The same could be done for the back glass. Almost a double pane system found in home window glass.
I do have an advantage though. Since the camper shell has been pretty well beat to death over the years, I'm not real worried about drilling holes in it. The lexan hail guard would be semi permanent in nature and really only removed to clean the underlying glass.
I have a few issues with Dave's style of flip over guard. Not the design of it, but the storage. I have antennas on the roof and an amber lightbar. I would not be able to fold it over these. I also have a cell phone antenna mounted in the middle of the camper shell. This would also be an obstacle.
Anyone out there with ideas?Dan Robinson
I wonder how feasible it would be to remove all of the expensive side windows altogether and temporarily replace them with lexan, even if it's just a 'roughed in' sheet held to the frame with clamps, then sealed with caulk or some other type of waterproof sealant. It definately wouldn't look pretty, and would probably require daily maintenance to keep the seals watertight and clamps set properly. But you'd have all of your glass safely in your garage when you returned from your expedition to the Plains.
I guess this would depend on the vehicle. I'd probably be more likely to break the glass trying to remove it myself.
Sounds like a Mythbusters project. Window/sunroof motors also might be able to do this as well.Rob_Davis
Jason, thanks for the clarification. I was picturing a very different scenario. I thought it was a sunroof that got hit, not a liftgate window. The former would have created a different sort of sound. And I didn't think of the steadycam effect either. I didn't mean to question your integrity. I simply thought the whole thing was so incredible that the probability that it was set-up had to be considered. Of course, that incredibility is what makes the video so cool!
How thick is your Lexan, and how much did it cost? Seems like 1/4 inch or greater Lexan wouldn't have the problem of flexing so much, so long as it is framed securely. Regardless, John and Mike's ideas of simple foam or bubble spacers in the center of the window would probably eliminate any potential for fatal flexation.
Dave, I agree that side and rear glass is quite expensive. What I said was that taking expensive measures to protect probably it isn't justified by a threat vs. cost analysis. Yes, it is expensive, but what are the statistical odds that you will ever have to replace it? If you have to replace it once, then you probably still haven't spent what it cost to cage all your windows. If you have to replace multiple windows multiple times, you've got horrible luck and should probably stop chasing! :lol:
I couldn't get a good look at RJ's concept, but I suspected that it was similar to my idea. Although, I see no reason to contour it, which would weaken the structure, as well as raise the fabrication cost significantly. Also, I would have the locking clamps down in the hood groove to keep it secured rather than at the windshield where security isn't as big of a concern. Actually, bungees would work fine in either case.
I think in all respects other than camera visibility, the expanded steel is superiour to lexan. Your concern regarding the airfoil nature of a sheet of Lexan across your hood illustrates another reason why. But, I don't think it is anymore likely to rip loose than a satellite dish or disk antenna on your roof is if you secure it well.
Robbie, damn fine idea about salvaging glass ahead of time! Drummond's article is the gift that keeps on giving in inspiration! That could save you hundreds, if not thousands of dollars!
Although I was intending to keep it simple, I love the hydraulic idea. The ability to deploy remotely is a very definite plus. An 80mph softball sized hailstone is going to split most helmets, as well as any part of your body not covered by the helmet. If they're already falling, I'm not getting out of the vehicle for ANY reason, even if the tornado is imminent. I had run a few ideas through my mind such as a cable (or simple parachute cord) running from the leading edge of the cage, to a roof rack support, and then down through a vent window in order to pull it into place remotely. Again, ghetto but potentially simple and effective. A few gas-shocks from the trunk or liftgate of a salvage yard car (thanks again, Drummond!) just might do the trick though!
John, my original idea was the reverse of my current vision, which was to have the shield up on the roof and hinge it down over the windshield when needed. That would present less of a concern with wind rattling it around (and possibly loose), as Dave suggested. But, like you, I really need that precious roof space for the antenna farm! That was the primary reason that I decided that the hood mount is the better option.
Again, I want to clarify that my ideas here are theoritical. I have a safety engineering background, so this is the sort of thing that I constantly ponder after having survived some serious hail encounters, as well as a couple of tornadoes. But I still haven't chased (apart from Skywarn activities), so I am looking forward to practical input from you guys who can relate real-life situations that we can learn from.
Thanks to everybody for the discussion! I don't think there are many people on this board who wouldn't like to take simple and practical precautions.John Diel
EF5
I really think the "flip up" design, though very feasable, isn't going to work well, unless your vehicle is dedicated to chasing and your really planning on getting splattered by big hail. It seems that you would almost have to have a permanent mounting and delivery system. It's not that it's a bad idea, it's simply that most vehicles these days are more aerodynamically designed and actually finding sturdy attach points on curved surfaces, is going to be the issue. The roof surfaces of most vehicles are better suited for this. All sorts of different roof mounting style can be accomodated much easier and probably better than a hood mounted system. Bungee cords are fine, up to a point. Loading and tie down straps are better, but more time is going to be required for a secure stow away and mount.
I do't think lexan over the windshield is really a good idea either. Unless you engineer in a wiper system. You ARE most likley going to move at some point. Visibility is a must. If you're getting blasted by big hail, I would think your going to try and seek some sort of shelter. This was evident in Dave's video right up until they were forced to hunker down and take the brunt by the downed power lines. The overhead type guard saved thier windshield. That much was obvious. No it wouldn't have lasted two more strikes, but it DID last long enough.Chris Sokol
EF5
Huh? I am assuming that this is a typo...
http://www.allauto.com/faq.html
Just one of thousands of examples online.Chris Sokol
EF5
For those of you that love to spend the $$$$$$ on your rig, here is another option:
http://bulldogdirect.com/lta_glasss.shtml
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