Aero RV Belly Pan(s)

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This is what a splitter is...
Stock Car Science: The Splitter Material



Very popular in NASCAR vehicles now...

[BamZipPow]

I did find this interesting photo of the Chevy Volt...

[aerohead]

Originally Posted by orbywan

When time permits I'm going to build some wheel fairings for the rear duallies and eventually for the front also. I just bought a copy of Hucho's book on aerodynamics and so far have been disappointed that it doesn't go into more details about the three things I am the most interested in at this point, which is front air dams, belly pans and especially wheel turbulence.

I say so far because I've barely scratched the surface so maybe the info is there and I haven't found it. Don't get me wrong, I think it's an awesome book.

I'm going to construct some wheel fairings using Three Wheelers construction technique, which is fiberglass over foam. I think that's the only way I'll effectively achieve the shapes I want to build. Hucho's book says the air at the rear wheels is coming at each wheel set at about a 15 degree angle from the middle. That's throwing an interesting curve ball in there, not sure what I'll do about that.

I think wheel turbulence on dually vehicles is considerable and so far somewhat ignored so I'm looking forward to that part of the build. I've incorporated mounting points on the pans in the back so I can build 'clip on' wheel spats, pants, whatever you want to call them. That way when I get a chance I can do some A/B/A testing to see how effective they are, and so I can take them off easily when it's time to play in the dirt again.

The hardest part of the pans build starts this evening, next up is one more somewhat easy pan and then the differential. I feel like this segment will be the difference between better than nothing and hell yes.

The university solar cars are a candy store for wheel fairing images.Ditto for their ultra-high mpg burn-and-coast wundercars.UC Davis.Univ of Michigan,etc..Honda Dream 2 Solar car,NUNA-3 ( Cd 0.077 ).

[orbywan]

Originally Posted by aerohead

The university solar cars are a candy store for wheel fairing images.Ditto for their ultra-high mpg burn-and-coast wundercars.UC Davis.Univ of Michigan,etc..Honda Dream 2 Solar car,NUNA-3 ( Cd 0.077 ).

Thanks Phil, I’ll check those out. I saw your photos on the progress on the boat tail trailer, looks like you're making progress. When are you leaving on your trip?

OK, pan # 5 is completed and installed. I used some fiberglass insulation on the cat and right behind the down pipe (photo # 10) since it is so close to the trans and now enclosed. I also put a vent right under the cat to help get some heat out. I also fabbed new driveshaft safety loops since the old ones hung down to the ground. Other than that it was just a big pain in neck panel.

Next up is the differential. My brain is cooked from the heat, hopefully inspiration for that will visit me in my sleep tonight. Ha.

[aerohead]

Originally Posted by orbywan

Thanks Phil, I’ll check those out. I saw your photos on the progress on the boat tail trailer, looks like you're making progress. When are you leaving on your trip?

OK, pan # 5 is completed and installed. I used some fiberglass insulation on the cat and right behind the down pipe (photo # 10) since it is so close to the trans and now enclosed. I also put a vent right under the cat to help get some heat out. I also fabbed new driveshaft safety loops since the old ones hung down to the ground. Other than that it was just a big pain in neck panel.

Next up is the differential. My brain is cooked from the heat, hopefully inspiration for that will visit me in my sleep tonight. Ha.

I plan to leave Sept. 10,catch a nights rest en route to Radium Springs for an overnight visit with the Gilkisons,then head west next morning.
I've got to make the driver's meeting the morning of the 14th,the 1st day of racing.
The gods of speed are having a hell of a laugh watching me try and get ready!

[orbywan]

Originally Posted by aerohead

I plan to leave Sept. 10,catch a nights rest en route to Radium Springs for an overnight visit with the Gilkisons,then head west next morning.
I've got to make the driver's meeting the morning of the 14th,the 1st day of racing.
The gods of speed are having a hell of a laugh watching me try and get ready!

Good luck getting it all finished. We've all been there and know how crazy that is. Good luck on the salt, I can't wait to hear the results. Go like hell and keep the shiny side up!

[orbywan]

I'm going to re-post this here as well since it is about this build:

Originally Posted by Otto View Post
Keep doing what you're doing. It's working.

Future suggested projects to consider:

1. Aero motorcycle mirrors to replace Dumbo the Elephant ear mirrors on Econoline van. Or, since you already have electronic cameras, eliminate outside mirrors entirely.

2. Garage door/lawn edging plastic air dam/spoiler

3. Pizza pan aluminum wheel covers

4. Wheel fairings per Prius or, better, per Aerohead's trailer

5. NACA duct inlets and outlets for belly pan cooling air

5. Aero-ized or covered windshield wipers. Maybe use of RainEx would make possible the complete elimination of windshield wipers.

6. Using redeployed existing cameras to fine tune all the above, esp. belly pan and wheel fairings, with real time tuft testing at highway cruise speed. After all, that's what you're trying to improve, so test at highway speed in case the airflow differs from lower speeds. End of quote

Thanks for the suggestions Otto. For #1, Since I have to see to either side in case the mirrors cut out I may reduce the size of the big mirrors and eliminate the fisheyes. I'm going to make some panels for either side to streamline the front considerably, which intersect with the mirror mounts so I'll address the side mirrors when I fab those panels.

#2, I'm going to try some testing with the new belly pans without the air dam for now, see how it does and leave the whole thing alone for a while so I don't beat it to death with a hammer. Then add an air dam later after I find some on-demand smoke. I think the air dam and the wheel mods are going to have to be smoke/flow tested to have the air flow around the wheels optimal, otherwise I'm just going to be stabbing in the dark with no idea of what's actually going on down there.

#3, Not possible in the front, and don't want to do that with the duallies. I'm concerned about overheating the brakes in the mountains when I tow various toys. I'll be restricting the air flow enough with the belly pans and the wheel fairings.

#4, Yes, I'm looking forward to that, I think there's a lot to be gained there if I can get some good video with the smoke/flow testing and can observe what the air is actually doing in those areas.

#5, I'm looking for some of those.

#6, Roger that. I'm going to hook up a DVR to the system so I can record some of the tests, it might be interesting to see. I'll have to figure out how to do a video link to here. Maybe UTube?

Well it should be up to a 100 or so out there, time for more fun with the differential. I'm taking the easy way out for now and doing it simple. When I get the equipment to do the smoke/flow testing I'll see how the air behaves back there and do the articulated cover if it needs it. For now I just have to finish this and get to the nearest trout stream so I have a reason to sit on my butt and drink beer.

Anybody know where I can get the best on demand smoke generator for on the road testing?

[Otto]

Originally Posted by orbywan

I'm going to re-post this here as well since it is about this build:

Originally Posted by Otto View Post
Keep doing what you're doing. It's working.

Future suggested projects to consider:

1. Aero motorcycle mirrors to replace Dumbo the Elephant ear mirrors on Econoline van. Or, since you already have electronic cameras, eliminate outside mirrors entirely.

2. Garage door/lawn edging plastic air dam/spoiler

3. Pizza pan aluminum wheel covers

4. Wheel fairings per Prius or, better, per Aerohead's trailer

5. NACA duct inlets and outlets for belly pan cooling air

5. Aero-ized or covered windshield wipers. Maybe use of RainEx would make possible the complete elimination of windshield wipers.

6. Using redeployed existing cameras to fine tune all the above, esp. belly pan and wheel fairings, with real time tuft testing at highway cruise speed. After all, that's what you're trying to improve, so test at highway speed in case the airflow differs from lower speeds. End of quote

Thanks for the suggestions Otto. For #1, Since I have to see to either side in case the mirrors cut out I may reduce the size of the big mirrors and eliminate the fisheyes. I'm going to make some panels for either side to streamline the front considerably, which intersect with the mirror mounts so I'll address the side mirrors when I fab those panels.

#2, I'm going to try some testing with the new belly pans without the air dam for now, see how it does and leave the whole thing alone for a while so I don't beat it to death with a hammer. Then add an air dam later after I find some on-demand smoke. I think the air dam and the wheel mods are going to have to be smoke/flow tested to have the air flow around the wheels optimal, otherwise I'm just going to be stabbing in the dark with no idea of what's actually going on down there.

#3, Not possible in the front, and don't want to do that with the duallies. I'm concerned about overheating the brakes in the mountains when I tow various toys. I'll be restricting the air flow enough with the belly pans and the wheel fairings.

#4, Yes, I'm looking forward to that, I think there's a lot to be gained there if I can get some good video with the smoke/flow testing and can observe what the air is actually doing in those areas.

#5, I'm looking for some of those.

#6, Roger that. I'm going to hook up a DVR to the system so I can record some of the tests, it might be interesting to see. I'll have to figure out how to do a video link to here. Maybe UTube?

Well it should be up to a 100 or so out there, time for more fun with the differential. I'm taking the easy way out for now and doing it simple. When I get the equipment to do the smoke/flow testing I'll see how the air behaves back there and do the articulated cover if it needs it. For now I just have to finish this and get to the nearest trout stream so I have a reason to sit on my butt and drink beer.

Anybody know where I can get the best on demand smoke generator for on the road testing?

Why not just use yarn and tape, or add tempera powder to water, dab on, and watch where the flow goes on the surfaces? Dirty motor oil works great, streaks left on the surfaces show the flow. That's what the German sailplane folks do, and they're the best in the business.

[orbywan]

Originally Posted by Otto

[/B]

Why not just use yarn and tape, or add tempera powder to water, dab on, and watch where the flow goes on the surfaces? Dirty motor oil works great, streaks left on the surfaces show the flow. That's what the German sailplane folks do, and they're the best in the business.

That's not a bad idea Otto, I may try that also. I just have a feeling if I can watch the air (smoke) go around and through these various shapes, I'll have a really good intuitive feeling for what needs to be done. It's kind of like seeing the tracks of an animal and trying to discern it's behavior verses seeing the animal as it leaves the tracks.

I also want to introduce it into the grille opening and see if I can get an idea of how and where the air is going through the belly pan. I'll bet there are volumes of interesting things, good and bad, going on inside and under the belly pans. How does the frontal intake air travel through the pan and where does it exit. Even if you provide openings it's going to go where the laws of fluid dynamics takes it, and I bet in a lot of cases it won't be through the places you think. I'm probably over doing it but I just find it interesting.

I especially want to see what all is happening around the wheels and in the wheel openings. Hucho and others say the air is actually hitting the wheels at anywhere from a 15 degree to a 60 degree angle from the inside. That's quite a range to design for, I'd like to see that for myself and see exactly what the angle is on this vehicle. I think if you design the wheel pants with that in mind and verify you got it right with the smoke, it could make a worthwhile difference.

[aerohead]

The commercial rigs were $1,100 in 1990.And I don't know if they'd produce the volume to fill the wake.
Shell makes an oil called something like 'Ondina',it's used in smoke generators,non-toxic.Just needs to be heated while soaked into some sort of matrix like steel wool.
Smoke bombs or smoke grenades would work.Not getting arrested would be the challenge,unless you could quench them on demand.
If you ever got rain,someone could film you from long distance as you pass in front of a dark,high-contrast background ( like a row of trees ).It really shows the water entrained within the wake.I get to see 18-wheeler wakes this way when its wet.