Aero RV Belly Pan(s)

[Otto]

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.

Bro, you have no idea how much I appreciate what you're doing, which but for other vehicle distractions was to have been my summer project on my Ford E150 Econoline gas guzzler conversion van. Being so grossly inefficient in aerodynamics, it's a target-rich environment for improvements like yours. So, thanks mucho for doing all that and sharing with the rest of us.

Several thoughts:

Note Hucho's picture of the Calibri in the wind tunnel (maybe page 67 but I'm not sure). Shows that due to bow wave, the airflow impacting the front wheels is at ~60 degree angle. Hence, the plastic garbage can fairing for the front wheels should be canted inwards quite significantly to fair the air whence it actually comes. Same story rear fairings.

Consider use of polyethelene foam, which can be hotwired and sculpted and which is color-fast and weather proof. RC model airplane guys have gone to this, much tougher than fragile styrofoam. Bump a curb with this stuff and it will likely not damage it. It's the type of foam used for pipe insulation, and floats.

Your camera setup is fantastic! Do tuft testing with tape and colored yarn, or dabs of tempera water paint, and see how the realtime flow goes, at highway speed. Or, rig up your sprayer with several Ts and lines to spots on the belly pan, squirt water with food dye out of them at highway speed, see where the flow goes, then fair accordingly.

Consider NACA inlets where needed in your Coro belly pan. Cut with utlity knife, reinforce edge with alu. foil tape.

If Coro needs stiffening locally, insert wood dowel rods of proper thickness into the flutes.

Consider self-inflating rear fairing that billows out at speed, droops when stopped. This could give weather protection to anything you need to carry on the back, suck as bike or motorcycle rack, etc..

Keep doing what you're doing! I'll hazard a guess that once your project is fine tuned, fuel economy will improve ~40% or more.

[orbywan]

Originally Posted by BamZipPow

I guess I would be looking fer a 3-4 channel DVR/monitoring setup. Nose, left/right on the aero cap, and an open channel fer portable monitoring.

I like wired cameras so I ruled out wireless setups fer now. Not sure I'd be willing to invest $1k in the system...

BZP, yes I know, this stuff is expensive. We have to use really good quality components because everyone tends to beat the heck out of this stuff, plus we frequently build the system to the customer’s specs. Not to mention the fact that if you have any problems or need advice on how to install it you get me or one of my techs on the phone in a heart beat instead of sending emails and trying to find a phone number to call someone who has a pulse and has a clue what they’re talking about.

The pan and tilt systems are designed specifically for mounting on the back of motor homes and big trucks. The housings are 6 inches in diameter, have 180 degree + panning and about 100 degree vertical movement (anything higher and you’re just looking at the clouds).

The easiest way to describe them is if you duct taped a spotter on the back of an RV or big truck, these cameras can see anyplace your spotter could look. Up, down, sideways, and anywhere in between. Zero blind spots. They have a control cable going to the dash area, and a remote control panel that mounts on the dash. If you use the 8-camera switcher, it also has a control pad. I attached some photos of various coaches and dash layouts, including some shots of the side cameras and nosecams we use on the RV’s.

Retail cost of a pan and tilt system right now, without a monitor, directly from the factory is $1250. We build them right here in Arizona using the best components and good old American labor. There are about 35 different RV manufacturers, Prevost converters and specialty builders using them these days. You can see a list and get more info at the site I gave you before, www. totalvisionproducts.com.

I’m trying to understand exactly what you referred to about ‘nose, left/right on the aero cap’. Can you explain that a little? Knowing what kind of vehicle you’re going to put them on would help a lot. There are on average 10 or 20 cameras that will go on any given location, and usually one or two that are actually the best for that location. When you say ‘nose’ I assume you’re talking about a front mounted camera on your vehicle, but I’m lost with the ‘left/right on the aero cap’, sorry, can you explain that a little?.

[orbywan]

Originally Posted by Otto

Bro, you have no idea how much I appreciate what you're doing, which but for other vehicle distractions was to have been my summer project on my Ford E150 Econoline gas guzzler conversion van. Being so grossly inefficient in aerodynamics, it's a target-rich environment for improvements like yours. So, thanks mucho for doing all that and sharing with the rest of us.

Several thoughts:

Note Hucho's picture of the Calibri in the wind tunnel (maybe page 67 but I'm not sure). Shows that due to bow wave, the airflow impacting the front wheels is at ~60 degree angle. Hence, the plastic garbage can fairing for the front wheels should be canted inwards quite significantly to fair the air whence it actually comes. Same story rear fairings.

Consider use of polyethelene foam, which can be hotwired and sculpted and which is color-fast and weather proof. RC model airplane guys have gone to this, much tougher than fragile styrofoam. Bump a curb with this stuff and it will likely not damage it. It's the type of foam used for pipe insulation, and floats.

Your camera setup is fantastic! Do tuft testing with tape and colored yarn, or dabs of tempera water paint, and see how the realtime flow goes, at highway speed. Or, rig up your sprayer with several Ts and lines to spots on the belly pan, squirt water with food dye out of them at highway speed, see where the flow goes, then fair accordingly.

Consider NACA inlets where needed in your Coro belly pan. Cut with utlity knife, reinforce edge with alu. foil tape.

If Coro needs stiffening locally, insert wood dowel rods of proper thickness into the flutes.

Consider self-inflating rear fairing that billows out at speed, droops when stopped. This could give weather protection to anything you need to carry on the back, suck as bike or motorcycle rack, etc..

Keep doing what you're doing! I'll hazard a guess that once your project is fine tuned, fuel economy will improve ~40% or more.

Thanks for some really good information Otto, I’m glad someone is actually reading this stuff. A ‘target rich environment’, that made me laugh. That’s a good way of saying you’re (I’m) driving a damn brick. The 15 degrees of yaw was on the Opel Calibra also, on page 183. They did say it could be more than 15, and 60 degrees of yaw looks possible in the 4.74 photo on the same page. That’s going to make for some bizarre looking fairings around the wheels. It says the yaw would be less for the rear wheels. My grandma would be loving this, yep, by guess and by golly.

Yeah, I’ve got some polyethylene foam but if the wind direction variation going over the wheels is this bad, maybe the round shape of the buckets might be better. ? So far I have not seen a need to let air in the pans, only out. When you restrict air flow this much on the underneath side, my concern is mostly for letting the air coming through the frontal area out through the pans, and various places, and not causing drag by backing the air up in there. That’s several reasons for restricting frontal air flow, especially through the front grille.

Now if I can just get the exhaust heat out without melting something I’ll be in good shape.

I should be ready to hang pan # 5 tomorrow and move on to the differential. I'll be very glad when this is completed.

[BamZipPow]

Originally Posted by orbywan

BZP, yes I know, this stuff is expensive. We have to use really good quality components because everyone tends to beat the heck out of this stuff, plus we frequently build the system to the customer’s specs. Not to mention the fact that if you have any problems or need advice on how to install it you get me or one of my techs on the phone in a heart beat instead of sending emails and trying to find a phone number to call someone who has a pulse and has a clue what they’re talking about.

The pan and tilt systems are designed specifically for mounting on the back of motor homes and big trucks. The housings are 6 inches in diameter, have 180 degree + panning and about 100 degree vertical movement (anything higher and you’re just looking at the clouds).

The easiest way to describe them is if you duct taped a spotter on the back of an RV or big truck, these cameras can see anyplace your spotter could look. Up, down, sideways, and anywhere in between. Zero blind spots. They have a control cable going to the dash area, and a remote control panel that mounts on the dash. If you use the 8-camera switcher, it also has a control pad. I attached some photos of various coaches and dash layouts, including some shots of the side cameras and nosecams we use on the RV’s.

Retail cost of a pan and tilt system right now, without a monitor, directly from the factory is $1250. We build them right here in Arizona using the best components and good old American labor. There are about 35 different RV manufacturers, Prevost converters and specialty builders using them these days. You can see a list and get more info at the site I gave you before, www. totalvisionproducts.com.

I’m trying to understand exactly what you referred to about ‘nose, left/right on the aero cap’. Can you explain that a little? Knowing what kind of vehicle you’re going to put them on would help a lot. There are on average 10 or 20 cameras that will go on any given location, and usually one or two that are actually the best for that location. When you say ‘nose’ I assume you’re talking about a front mounted camera on your vehicle, but I’m lost with the ‘left/right on the aero cap’, sorry, can you explain that a little?.

Sorry...was kinda thinking out loud.

My aero cap build thread...
http://ecomodder.com/forum/showthrea...dea-15137.html

Yes...nose = front part of the hood of the Toyota T-100 pickup truck. Not sure I'd want something in the license plate arena...too low fer my liking.

Since I don't have any windows in my current aero cap build/config, I was looking at some cameras to look out the sides/back/blind spots with. I'm not at a stage where I could install expensive cameras as someone could easily remove them with a knife cutting through the Coroplast. But at least I know where to look to fer some great gear when/if the time comes.

[orbywan]

Originally Posted by BamZipPow

Sorry...was kinda thinking out loud.

My aero cap build thread...
http://ecomodder.com/forum/showthrea...dea-15137.html

Yes...nose = front part of the hood of the Toyota T-100 pickup truck. Not sure I'd want something in the license plate arena...too low fer my liking.

Since I don't have any windows in my current aero cap build/config, I was looking at some cameras to look out the sides/back/blind spots with. I'm not at a stage where I could install expensive cameras as someone could easily remove them with a knife cutting through the Coroplast. But at least I know where to look to fer some great gear when/if the time comes.

No worries mate, when I get a chance I'll look in my 'distressed' locker and see if we have something inexpensive we can throw together for your cruiser. Something that wouldn't be a big deal if someone absconded with it. A little bit of work, you might could make it low profile so people wouldn't notice.

I had five minutes to look at your pickup cap, looks like it's coming along nicely. Great results so far. What engine is in your Toyota?

[orbywan]

Here's some info I just got from Three Wheeler Jim that I thought some people might find interesting concerning belly pans and specifically the issue of hot exhaust areas and how to deal with them. Since I saw in his belly pan thread he was using pink fiberglass insulation to control the heat, I was asking him primarily on advice concerning wrapping the exhaust in critical places with Owens-Corning pink fiberglass because it has a very high melting point and is obviously a good insulator

There's also some info and questions on the design of wheel pants -

Originally Posted by 3-Wheeler

The area I want to wrap is up inside the second pan and I think will stay dry. I'll wrap it in alum foil to be sure. Should I remove the paper backing from the fiberglass?

Thanks Jim.

Rod

Hi Rod,

Whoops, I just saw your message.

Yes, by all means remove the paper. The paper only has a flash point of 400F or so, and the fiberglass melts over 2000F, because it's primarily glass.

I have wrapped the first cat con on the Insight with glass and experienced no overheat problems at all with the glass this close to the exhaust ports on the engine.

Hope this helps, Jim.[/QUOTE]

OK, I'll pick some up and start wrapping. I am way ready for this part of the job to be over, panning a vehicle this long is a major test of endurance.

I plan on building some wheel fairings to cut down on drag. Hucho's book says that the wind hits the front and rear wheels from the center of the vehicle outward due to bow wake, at an angle anywhere from 15 degrees on up to 50 or 60 degrees maybe. That really throws some weird stuff into the wheel pants design. Do you have any opinion on how I should go about designing the shape of wheel pants, especially on the duallies? Since the air could be hitting them diagonally at a 20 to 60 degree angle from the inside, that's going to make for some wacky shapes I would think.

There are so many variables here. I think this calls for some on demand smoke and adding a DVR to my camera system so I can do road tests with the smoke and record where the air is actually going, then design the pants accordingly, yes? I'm going to cut and paste this onto the thread too, I think lots of people might be interested in this. Hope you don't mind. Hopefully anyone with knowledge in this area will chime in.

Thanks for the help Jim!

Rod

[Otto]

Originally Posted by orbywan

Thanks for some really good information Otto, I’m glad someone is actually reading this stuff. A ‘target rich environment’, that made me laugh. That’s a good way of saying you’re (I’m) driving a damn brick. The 15 degrees of yaw was on the Opel Calibra also, on page 183. They did say it could be more than 15, and 60 degrees of yaw looks possible in the 4.74 photo on the same page. That’s going to make for some bizarre looking fairings around the wheels. It says the yaw would be less for the rear wheels. My grandma would be loving this, yep, by guess and by golly.

Yeah, I’ve got some polyethylene foam but if the wind direction variation going over the wheels is this bad, maybe the round shape of the buckets might be better. ? So far I have not seen a need to let air in the pans, only out. When you restrict air flow this much on the underneath side, my concern is mostly for letting the air coming through the frontal area out through the pans, and various places, and not causing drag by backing the air up in there. That’s several reasons for restricting frontal air flow, especially through the front grille.

Now if I can just get the exhaust heat out without melting something I’ll be in good shape. :thumbup:

I should be ready to hang pan # 5 tomorrow and move on to the differential. I'll be very glad when this is completed.

I can't find my Hucho photocopied pages at the moment, but the Calibra wind tunnel picture I refer to is taken from the left front, shows longitudinal smoke trail diverts outboard at about 60 degree angle, apparently due to bow wave effect, with area of entrainment due to front wheels. So, fairings of front wheels would need to be canted in (pigeon toed) into the relative wind. Rear wheels need fairings smoothing the airflow out somewhat laterally, at a lesser angle, more or less like Prius has.

Outlets: NACA did lots of work on these during WWII. An efficient outlet is not just an efficient inlet turned around backwards. Rather, it should bring exhaust air as parallel to ambient flow as possible. Carefully study the exit gill geometry of fast swimming fishes, like tuna. Venturi and Bernoulli dynamics draw the water over the gills and out, else the fish does not get breakfast, but rather is breakfast. With Coro panels, this should be easy. The somewhat recessed leading edge of the exit ramp should have radiused edge contour. Proper inlets and outlets make the craft into a linear pump, with no moving parts... Study engine exit geometry of the Arnold AR-5 sport plane, available from Google pics search.

Hot spots around exhaust pipes, etc.: Consider paneling this part of the belly with aluminum window screen, as alu is a superb heat conductor, so instantly dissipates any hot spot. Others with Coro belly pan experience report that the stuff can be used much closer to hot spots than I had imagined, but any such Coro could be faced or edged with aluminum foil tape, similar to duct tape. For the hottest spots, alu. window screen. Might could get some suitable stuff already framed in rectangular panels from a building recycling store, or discarded after a house remodel.

Some folks report aero improvement by sealing up those gaps in the face of the vehicle. Ford Econoline vans may so profit by use of strips of polyethelene pipe insulation, properly inserted into such gaps.

Your Econoline van has a plastic valence under the front bumper exactly like mine. I've seen others with valences that hang several inches lower, acting more as an air dam, so maybe some research at a Pick and Pull junkyard would find a bigger dam to fit that stock metal bumper, and also serve as a leading edge mounting surface for the belly pan. Alternatively, such valence could be a mounting surface for a combined splitter and belly pan. The Porsche guys figured out by trial and error that a splitter of ~4" protrusion is optimum.

The factory aluminum wheels on my E150 van are perfect candidates for alu. pizza pan covers of correct diameter, as the outer lip of the wheel would seat the pizza pan just flush, while supporting vertical loads from potholes.

Outside stock mirrors on my van are pretty big. Why wouldn't aero motorcycle mirrors work, with maybe 1/5 the frontal area and better shape?

If using insulation, consider rock wool or mineral wool: Has twice the heat capacity of fiberglass, holds a lot less moisture, and is less friable. Also, could use exhaust header wrap to keep the heat in the pipe. Apply with hose clamps, and available at auto parts stores.

Others with belly pans report the stuff makes the vehicle a lot quieter: Less turbulence & buffeting of the floorboards, and less engine noise since it takes less power to propel the more streamlined vehicle. I hope you have the same result.

[BamZipPow]

Originally Posted by orbywan

No worries mate, when I get a chance I'll look in my 'distressed' locker and see if we have something inexpensive we can throw together for your cruiser. Something that wouldn't be a big deal if someone absconded with it. A little bit of work, you might could make it low profile so people wouldn't notice.

I had five minutes to look at your pickup cap, looks like it's coming along nicely. Great results so far. What engine is in your Toyota?

My engine size is the 3.4L, 5vz-fe, 6 cylinder.

I'm gitting ready to take the sides of the aero cap apart so I can rework the brackets. It happens...

[Otto]

Originally Posted by orbywan

Thanks for some really good information Otto, I’m glad someone is actually reading this stuff. A ‘target rich environment’, that made me laugh. That’s a good way of saying you’re (I’m) driving a damn brick. The 15 degrees of yaw was on the Opel Calibra also, on page 183. They did say it could be more than 15, and 60 degrees of yaw looks possible in the 4.74 photo on the same page. That’s going to make for some bizarre looking fairings around the wheels. It says the yaw would be less for the rear wheels. My grandma would be loving this, yep, by guess and by golly.

Yeah, I’ve got some polyethylene foam but if the wind direction variation going over the wheels is this bad, maybe the round shape of the buckets might be better. ? So far I have not seen a need to let air in the pans, only out. When you restrict air flow this much on the underneath side, my concern is mostly for letting the air coming through the frontal area out through the pans, and various places, and not causing drag by backing the air up in there. That’s several reasons for restricting frontal air flow, especially through the front grille.

Now if I can just get the exhaust heat out without melting something I’ll be in good shape. :thumbup:

I should be ready to hang pan # 5 tomorrow and move on to the differential. I'll be very glad when this is completed.

I can't find my Hucho photocopied pages at the moment, but the Calibra wind tunnel picture I refer to is taken from the left front, shows longitudinal smoke trail diverts outboard at about 60 degree angle, apparently due to bow wave effect, with area of entrainment due to front wheels. So, fairings of front wheels would need to be canted in (pigeon toed) into the relative wind. Rear wheels need fairings smoothing the airflow out somewhat laterally, at a lesser angle, more or less like Prius has.

Outlets: NACA did lots of work on these during WWII. An efficient outlet is not just an efficient inlet turned around backwards. Rather, it should bring exhaust air as parallel to ambient flow as possible. Carefully study the exit gill geometry of fast swimming fishes, like tuna. Venturi and Bernoulli dynamics draw the water over the gills and out, else the fish does not get breakfast, but rather is breakfast. With Coro panels, this should be easy. The somewhat recessed leading edge of the exit ramp should have radiused edge contour. Proper inlets and outlets make the craft into a linear pump, with no moving parts...

Hot spots around exhaust pipes, etc.: Consider paneling this part of the belly with aluminum window screen, as alu is a superb heat conductor, so instantly dissipates any hot spot. Others with Coro belly pan experience report that the stuff can be used much closer to hot spots than I had imagined, but any such Coro could be faced or edged with aluminum foil tape, similar to duct tape. For the hottest spots, alu. window screen. Might could get some suitable stuff already framed in rectangular panels from a building recycling store, or discarded after a house remodel.

Some folks report aero improvement by sealing up those gaps in the face of the vehicle. Ford Econoline vans may so profit by use of strips of polyethelene pipe insulation, properly inserted into such gaps.

Your Econoline van has a plastic valence under the front bumper exactly like mine. I've seen others with valences that hang several inches lower, acting more as an air dam, so maybe some research at a Pick and Pull junkyard would find a bigger dam to fit that stock metal bumper, and also serve as a leading edge mounting surface for the belly pan. Alternatively, such valence could be a mounting surface for a combined splitter and belly pan. The Porsche guys figured out by trial and error that a splitter of ~4" protrusion is optimum.

[orbywan]

Originally Posted by Otto

I can't find my Hucho photocopied pages at the moment, but the Calibra wind tunnel picture I refer to is taken from the left front, shows longitudinal smoke trail diverts outboard at about 60 degree angle, apparently due to bow wave effect, with area of entrainment due to front wheels. So, fairings of front wheels would need to be canted in (pigeon toed) into the relative wind. Rear wheels need fairings smoothing the airflow out somewhat laterally, at a lesser angle, more or less like Prius has.

Outlets: NACA did lots of work on these during WWII. An efficient outlet is not just an efficient inlet turned around backwards. Rather, it should bring exhaust air as parallel to ambient flow as possible. Carefully study the exit gill geometry of fast swimming fishes, like tuna. Venturi and Bernoulli dynamics draw the water over the gills and out, else the fish does not get breakfast, but rather is breakfast. With Coro panels, this should be easy. The somewhat recessed leading edge of the exit ramp should have radiused edge contour. Proper inlets and outlets make the craft into a linear pump, with no moving parts...

Hot spots around exhaust pipes, etc.: Consider paneling this part of the belly with aluminum window screen, as alu is a superb heat conductor, so instantly dissipates any hot spot. Others with Coro belly pan experience report that the stuff can be used much closer to hot spots than I had imagined, but any such Coro could be faced or edged with aluminum foil tape, similar to duct tape. For the hottest spots, alu. window screen. Might could get some suitable stuff already framed in rectangular panels from a building recycling store, or discarded after a house remodel.

Some folks report aero improvement by sealing up those gaps in the face of the vehicle. Ford Econoline vans may so profit by use of strips of polyethelene pipe insulation, properly inserted into such gaps.

Your Econoline van has a plastic valence under the front bumper exactly like mine. I've seen others with valences that hang several inches lower, acting more as an air dam, so maybe some research at a Pick and Pull junkyard would find a bigger dam to fit that stock metal bumper, and also serve as a leading edge mounting surface for the belly pan. Alternatively, such valence could be a mounting surface for a combined splitter and belly pan. The Porsche guys figured out by trial and error that a splitter of ~4" protrusion is optimum.

Thanks Otto, more good information. When you say splitter do you mean they run an air dam on each side of the front with a gap in the center? I saw that a while back and wondered what that was about.

I just went to Lowes and bought some fiberglass insulation that has an aluminum foil backing on it, close enough for now. They've got silicone wrap at the auto parts store but I didn't want to spend $50 on it.

Good point on the exit air. The louvers I bought at the demo yard are adjustable so I can lay them all over to get a good angle on the exhausted hot air.

This undercarriage is turning out so smooth I'm going to leave the front air dam for later. If I can find a good source for on-demand smoke I think that will give me some good clues as to how to build the front wheel pants (and rear especially), which may include a split air dam up front.

I'm stumbling around in the dark here trying to figure this out but everyone keeps turning on flashlights here and there to help me find the way. Thanks to everyone for their help!