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  #1  
Old 06-03-2011, 10:42 PM
Greg Arehart's Avatar
Greg Arehart Greg Arehart is offline
 
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Location: Delta, CO/Atlin, BC
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Default Gravel deflectors

Welllll.... I'm in the end stages of modifying my RV-9 to take bigger wheels for landing on some less-than-optimal strips. The new wheels (8.00 x 6) will obviously be too big for normal fairings, so I am designing (or thinking of designing) some gravel deflectors in an attempt to save my paint. Thus far, I've found a couple designs out there, but not much. Here are a couple photos of some Cessna deflectors:





So, I'm polling the collective wisdom here to see if anyone has

1) links to other photos/designs out there; or
2) thoughts on optimal design (like, how low the bottom of the deflector should be above the ground to keep gravel off the tail); or
3) any other words of wisdom on building these.

Thanks,
greg
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  #2  
Old 06-03-2011, 10:52 PM
Sig600 Sig600 is offline
 
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Greg! Bob showed me your steed, looks good!

Ever seen that show "Flying Wild Alaska?" All their planes have gravel deflectors like your second picture.
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  #3  
Old 06-04-2011, 02:26 AM
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Andrew M Andrew M is offline
 
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Location: Secluded Lake,Alaska (AK49)
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Default Gravel delectors.

Hey Greg,
I work for Hageland Aviation, the Flying Wild Alaska guys. The lower photo you have is the Aero Twin deflector. It is made from square stock, about 3/4" with 1/8" or 3/16" plate where it mounts, and fiber reinforced 1/4" rubber. The deflector mounts on the inboard side of the axle,and shares the same bolt as the axle. The STC puts longer bolt there. The rubber is longer than it needs to be so it can be redrilled after it wears out, and attaches with 3/16" hardware. The rubber is trimmed so it just touches the tire, the tire wearing the rubber to fit. The vertical piece of rubber is about 3" above the ground. We don'tget 207's through our shop very often, that would be the Bethel guys. I can get you 208 Caravan photos if you like.
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-9 empennage
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  #4  
Old 06-04-2011, 09:56 AM
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Greg Arehart Greg Arehart is offline
 
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Andrew,

Thanks for the info - truly amazing the expertise on this forum! So, a couple other questions/thoughts.

Do you have any sense how much lateral gravel spray occurs? Obviously the second design doesn't really cover much laterally, at least on the outboard side of the wheel.

Right now I'm thinking a single flat plate at about 45 degrees angle (down and back from the wheel), rather than the two different pieces at 90 degrees in the photo. This would be simpler to build and would store flat for travel (I don't plan on having the big wheels on all the time). With the RV, I could probably build it from less beefy material, as I can attach the bracket on both sides of the wheel.

I probably don't need photos of the 208 unless the design is significantly different. I'm mostly thinking about aerodynamics (minimizing any excess drag) and the gravel spray angle/direction.

cheers,
greg
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  #5  
Old 06-04-2011, 10:38 AM
10TJ 10TJ is offline
 
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Location: Portland OR
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Default Big Tires

Greg:

I put 8:00 X 6 tires on an RV-10 and used the 10 wheel pants by opening them up to fit the larger tires. You will have a lot of tire exposed at the bottom, but will still not see too much speed reduction. I have landed on a lot of gravel and some rock, but have had no damage. Just a thought.

Tim James
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  #6  
Old 06-04-2011, 10:56 AM
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Default Mud spray

Greg
These deflectors act as much as a tire scraper as a deflector. Even so, the wing bottpms still come home with a mud stripe after flying on a rainy day. Leading edges of horiontal stabilizers, bottoms of flaps and elevators take a beating as well. What really kick up the rocks is being hard on the brakes, espessially when you first touch down. Once those rocks are in motion, the deflector helps, but they do bounce. I'm not sure what 45 degrees will do. Using a "plate" as apposed to something that will dissipate some of the rock enery is another question. Please let me know what you come up with as I am on a gravel strip and have hundreds of gravel places to go.
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  #7  
Old 06-04-2011, 11:07 AM
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Andrew,

I'll keep you posted. Maybe even fly over and show you what I ended up with later in the summer! I definitely will use some rubber and contour to the tires, as well as popriveting or somehow attaching some rubber to the plate to dissipate the energy.

Tim,

Interesting idea. Probably not enough time to do that this summer, but may be a winter's project. What kind of speed change did you see?

cheers,
greg
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Last edited by Greg Arehart : 06-04-2011 at 06:25 PM.
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  #8  
Old 09-02-2013, 05:56 PM
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Thread revivification! The grass is coming in slooooooooooowly on my strip and there is some gravel - so how about pics of what people have come up with. I searched and read every thread with "gravel." I would like to see more pics/details of THESE. http://www.vansairforce.com/communit...lectors&page=5. Greg Arehart????
Thanks, Bill H
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  #9  
Old 09-02-2013, 07:48 PM
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Greg Arehart Greg Arehart is offline
 
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Bill,

I never ended up using the deflectors last year - seemed that I didn't really need them as long as I was careful on the brakes. Mind you, I didn't land on any gravel bars etc, but did go to some pretty gravelly strips. I did get a few paint chips, but nothing really significant. I'm currently in northern BC working on my cabin (without the RV unfortunately) but if you'll remind me in early October, I'll send you some additional photos.

Cheers,
Greg
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  #10  
Old 09-02-2013, 08:06 PM
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Quote:
Originally Posted by Greg Arehart View Post

....snip...


I'm currently in northern BC working on my cabin (without the RV unfortunately)

...snip...

Cheers,
Greg

Greg you got quite a location for your cabin. Fantastic view of the lake and mountains! I am following your project via your Picasa album. What the state of gravel at Atlin airstrip? Can little wheelies handle it? Your camp is a quick hop from PAJN with picturesque landscape on the way.
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