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Old 03-29-2017, 04:55 PM   #1 (permalink)
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Bug catcher/deflectors do they help or hurt?

Hear in Montana they sand/gravel and spray de-icer to reduce the number of winter accidents. The down side de-icer is corrosive, sand and gravel sand blasts the body and glass exposing raw metal to the corrosive de-icer.
The majority of rock strikes come from being passed by faster traffic.
So far this winters and I need a new windshield. 4 rock spider cracks and the windshield is pitted badly enough that my view is now hazy and wipers are lacking in there proformance..

1)How would a bug catcher effect aero? Positive or negative?
The advertised function is to redirect the air flow above the windshield, reducing the number of bugs and sand/gravel that hit the windshield. If it proforms as advertised it should smooth my brick shape some what.

2)shape of bug catcher? The old school flat pice of plexiglass is not my intention, more like a 2nd generation contured.
.
3)Any negative Cd should be less than a new windshield annually.
Any suggestions or alternatives are welcome
Gumby Stay Flexible

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Old 03-29-2017, 08:44 PM   #2 (permalink)
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They save windshields, they hurt fuel mileage. They also make the windshield washers spray on the hood instead of the windshield. In your case go for it!
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Old 03-30-2017, 03:09 PM   #3 (permalink)
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I found this article
Quote:
Finally, to share some data: The National Research Council of Canada has done some testing in a wind tunnel on commercial trucks to see the effect that bug deflectors have on fuel economy. According to their study, bug deflectors decrease fuel economy 1.5% (or so). Thatís not a heck of a lot of change. Another study of commercial trucks pegged the fuel economy decrease at about 3%. So the data suggests that the fuel economy impact of a bug deflector is minimal (1.5-3%).
Bug Deflectors Purpose and Gas Mileage - DualLiner Bedliner Blog
It is referring to big rigs.
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Old 03-30-2017, 04:02 PM   #4 (permalink)
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In most applications I would say they hurt. Its possible that some big trucks with vertical windshields COULD benefit from a deflector if the deflector is in the middle of the hood or closer to the windshield.
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Old 03-30-2017, 08:57 PM   #5 (permalink)
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You could also try the V-Spoilers / Airtab style Vortex generators on the front 3rd of your hood..

With the big rigs, a few studies have shown an increase in fuel economy ..they do deflect bugs, and dirt from what I have seen..Doubtful on a big stone being deflected by an air curtain, but might change its trajectory somewhat..

Saying that, a 3" tall piece of plastic at the front of the hood will probably not stop a big stone regardless..parabolic arc of the stones trajectory would most likely bypass it as well..

In Australia the old skool way was a big metal screen in front of the windscreen, to protect from locusts / stones etc smashing the pre-laminated days of windscreens...doubt it would be good for fuel economy however lol

Other way...consider a laminate screen..kind of like a pull off on a motorbike helmet visor..use a clear or similar window tint on the outside..

And only other way I can think of...
There is a ceramic product out there that is put on your cars paint..that also is applied (Sprayed) across windows...results in an ultra hard surface that can be refinished..not cheap, but may help on the windscreen..
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Old 03-30-2017, 09:25 PM   #6 (permalink)
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My Jeep has a vertical windscreen. I have the Jeep branded hood deflector. When sprayed with a garden hose it helps deflect the flow, landing about half way up the windscreen.

What happens in actual driving is anybody's guess. The deflector is there to save the leading edge of the hood from flying branches.

I have quartz ceramic protection on most of my cars, that might protect from long term sand etching, but unlikely to help with stones as such.
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Old 03-31-2017, 12:01 AM   #7 (permalink)
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My new Ram has no less than 5 chips that haven't spread yet. I don't know if I should try and fix them for about $70 in diy kits or just let them crack and replace the whole windshield. If that happens every winter and a deflector could stop it, that would be worth it. I don't think a deflector will deflect the rocks big enough to cause a chip, it's more for lightweight stuff like bugs.
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Old 04-03-2017, 04:35 AM   #8 (permalink)
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We have the same problem in Sweden, salt on the major roads and gravel on the smaller roads.

I have been lucky the past two winters and not had any problems. The winter before I changed the screen about this time of year, then a week later a chip, luckily it was repairable and I didn't need a new screen.

I suppose you'll never really know about a deflector as a determined stone will get through, but it could certainly help with some of the less determined ones. As you said if the extra fuel cost is less than a screen it is most likely worth it.

With repairing the minor damage them don't you have local windscreen repair shops that can inject resin ? I have tried the kits but the professional jobs (at least here) are cheaper and better. It also depends on how quick you get it repaired to prevent the ingress of dirt / water - a tip I was given was to carry a roll of 2 inch wide clear tape, if I hear a pang pull over asap and take a look, if there is any damage get a piece of tape over it.
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Old 05-08-2017, 03:51 PM   #9 (permalink)
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Preliminary results

Before the bug shield.
The wipers had a significant aero load on there down stroke.

And they woud be pushed slightly up the windshield.

Rain accumulatios and water puddling from the wipers would be pushed up the windshield in a radiating sun ray like pattern with short straight drop streeks keeping the windshield mostly clear.
Bug strikes went from sheet metel just below the windshield gasket up. Grass hopers and dragonflies wedging under the wipers are the worst

This is the typical pattern I've seen on my truck naked. Including in tuft testing .


Now with the bug shield
The water flow on the hood is reversed flowing to the front corners insted of to the rear.

Water on the windshield will sits virtually stationary getting buffeted wiggling up and down and slightly to the out sides. This requires use of the wipers more frequently,as the water will form into ribbons and dots. Puddles no longer get pushed up and off the glass they now go down into the calw vent.

Bug strikes are now in the parts of the truck seen in the image below, only the top 4-6" of the windshield has bug strikes, above my line of sight . Were every square inch showin has 1-10 splattered bug from my last run from Montana to Ogden,Utah on May6 . There are 10 total strikes on tbe lower part of the windshield




Not having to stop and scrape the bug mill off the windshield, evry 10-20mi some times, will have a long turm positive impact on FE

Wipers no longer ride high. They buffet badly, in constant motion above 45mph. Showing the previous owners use of a bug shield was a likely cause of the driver's side wiper arm having slop in the bushing. (The repair kit for witch is no longer available )

Sand kicked up off the lines /rumble strips (cuts on the shoulder to wake drivers) no longer sounds like standing in a glass box in a sandstorm. Sand strikes are not completely eliminated, but significantly reduced.
Side profile

As to how FE is impacted is unknown.
I also added the airdam 2.5"+2through 4"extension wile I was home. Pulled 23.83mpg 405.02mi via gps@70mph driving through a thunderstorm system front with 20-40 sustained/ gusts over 70mph head on wind so an air speed of 90-140+mph
Any losses I fill are still a gain, in reduced maintenance cost. And body damage not suffered from compromised visibility (moose make big expensive dents).
Dreem big chisel down to reality

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1st gen cummins 91.5 dodge d250 ,HX35W/12/6 QSV
ehxsost manafulld wrap, Aero Tonto
best tank: distance 649gps mi 24.04 mpg 27.011usg
Best mpg : 31.32mpg 100mi 3.193 USG 5/2/20


Former
'83 GMC S-15 Jimmy 2door 2wd O/D auto 3.73R&P
'79 Chevy K20 4X4 350ci 400hp msd custom th400 /np205. 7.5-new 14mpg modded befor modding was a thing
87' Hyundai Excel
83 ranger w/87 2.9 L FI2wd auto 18mpg on the floor
04 Mitsubishi Gallant 2.4L auto 26mpg
06 Subaru Forrester XT(WRX PACKAGE) MT AWD Turbocharged 18 plying dirty best of 26mpg@70mph
95Chevy Blazer 4x4 auto 14-18mpg
04 Chevy Blazer 4x4 auto 16-22mpg



Last edited by gumby79; 05-08-2017 at 09:07 PM.. Reason: Hit rong button
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