Ed- as with most aero devices, location is everything. The purpose of this type of device is to energize the boundary layer between free stream air and your vehicles body, with the intention that a more energized boundary layer will stay more tightly attached and leave a smaller wake. For that reason, it's pointless to pay the penalty of an increasingly thick boundary layer all down the sides of your trailer, and then incur the drag penalty of vortex generators to create vortices right at the rear separation edges (where the vortices can no longer do anything to help you.) If you're feeling so inclined, it would be nice to see what the effect is of placing the VG devices about 2.5 feet aft of the leading edges of the trailer sides instead of right at the rear separation edge. In any case, as you've rightly pointed out you are likely to see much greater aero gains by cleaning up / streamlining other aspects of the trailer (the roof looked particularly "dirty").
Yeah, with aircraft, VGs are supposed to improve airflow across the surface of the airframe behind the VGs. That's why aviation VGs tend to be placed near the front of lifting surfaces, with the expectation that they will up the aero across the rest of the wing afterwards. In technical papers, I have read that the ideal placement was 20% of the distance back from the leading edge. So following that theory, placing VGs at the rear of a land vehicle would only improve the airflow over the nonexistent vehicle body behind your trailer's rear end. Thus, no bueno. I remain a little skeptical. I just read a technical paper on one of my favorite planes, the Cessna 208 Grand Caravan, which said that there is negible benefit from leading edge VGs on that plane either, because the wing already works about as well as it can for its intended kind of flying. They found only a 1.2% increase in airflow and lift at slow speeds under very limited, specific conditions. #NotWorthIt But pilots of plenty other light planes swear by the VGs on their units. 🤷🏻♂️
The mpg gain will be extremely minimal at best. Drag per vehicle is complex and simply changing one item is highly unlikely to provide any appreciable ROI. However, for vehicles with huge handling issues, VGs can effectively cure a huge issue of woe. My RV could be a bear to handle, not only at freeway speeds but even at 40 mph in a crosswind. Two lane country roads were nightmare inducing. In fact, I bought it from a couple that were too scared to drive it because even a Ford Escape passing by would cause it to push to the shoulder then suck it back across the lane dividing line. Seriously, you would spend as much your driving time watching your mirrors for approaching vehicles as you would watching where you were going. They had thrown thousands of dollars into suspension upgrades with little to no improvement and were relieved to sell it, even at a huge loss. (no need to laugh, it is a Class A on a Workhorse Chassis a.k.a. a Chevy P series frame and well known for this issue.) A series of these around the rear of the coach extends the air flow past the vacuum bubble following the rear so that passing vehicles have almost zero effect. What used to be a two-handed, white knuckle driving nightmare becomes a single handed, easy to drive vehicle. So, if you have a vehicle or trailer that gets pushed around by passing vehicles or crosswinds I'd seriously be looking into these (provided you don't have any chassis maintenance issues. These won't cure bad springs, tie rods,etc.) If you drive a tractor/trailer or heavy straight truck over 100,000 miles/year I'd consider them. The science behind vortex generators? czcams.com/video/9Whd_KnsLKE/video.html
Well my ROI wasn't bad considering I printed them myself... Total cost maybe 10 bucks lol. After completing the video, I realized that for the final test, my wife was with me. So accounting for my wife's weight (about 125 pounds) I figure the air tabs saved me at Best 0.3kwh of energy. Also, had I been traveling at a higher speed, I may have seen more improvement. In any event, they cost me next to nothing, and they look interesting lol
i'm a sucker for all this aerodynamic stuff so it was definitely interesting to see your little experiment. :D what about "trailer tail fairings"? did you consider or tried those??
Just came across your video. I’m trying to find a way to improve aerodynamics for my set up. I’m more traditional, Tundra pulling a 26’ RV. Speed of course is the biggest factor but would like to keep up with traffic. I have a trifold bedcover on my truck, I want to try and angle the first part up at about 30 degrees to see if that would help get the air over the trailer. Those air tabs have been out a long time and I think if they worked would have been adopted by all the big trucking companies but have not.
Yeah, I think the most they may have helped was about 0.3kwh of energy savings. I calculated that based on the extra weight I carried on the final test (my rather light weight wife lol) ... She wasn't with me on the "before" test. I may have seen slightly better improvements at higher speeds though. 🤷 If you have to buy them, they're not worth it. But if you can 3d print them like I did, then why not.. can't hurt.
Make a truncated boattail from Coroplast, tape and some angle brackets, or even hinges to make it foldable. Commercial trucks use them. Will save your minimum 15% and costs next to nothing. You'll also be the dad magnet of the camping grounds.
Lol.. dad magnet. I actually had fully intended to do that. But as we got closer to departure day, I decided not to bother. I actually went to the hardware store specifically to purchase the needed supplies and decided there that it just wasn't worth the headache. Plus there's a bunch of stuff hanging off the back of the trailer getting in the way. Not to mention the tail light situation. In any event, we're already 1000km into our trip, and things are going pretty good as is 😁
@@edsgarage001 Love it, go explore. I camp too with my EV but we sleep in a tent and we eat in diners. Wouldn't waste my precious KWh on a trailer. Might get a rear mounted luggage box one day.
Rather like cycling into a strong wind and then turning round and heading back, high winds are not a zero gain. To get the same result on a windy day means they are doing something. Perhaps experiment with teh locations too. Were they too close to the trailing edge, hence not allowing vortex to form, or is that the recommended location?
According to the website that sells the same things, this was the recommended location. I did the test in both directions. I just don't think I was going fast enough to see a difference.
@@midnight121190 i did add them, i tried 3 varieties, they all had the same results albeit very small gains for my application and placements. if you are into backyard science have at it. just make sure you take as much data as you can, to assure they are helping and not hurting economy or stabilization.
Yes... You're right. I probably would have seen some improvement at higher speeds. However I realized afterwards that they may have provided a slight savings, as on the final test my wife was with me.. so despite an extra 125 LBS (ish) I had the same result. So that equates to about 0.3kw of savings lol Unfortunately... It's a little late to test it now, as I won't have a pre-install run to go off of. I'm not ripping them all off now lol 😆
Ed- as with most aero devices, location is everything. The purpose of this type of device is to energize the boundary layer between free stream air and your vehicles body, with the intention that a more energized boundary layer will stay more tightly attached and leave a smaller wake. For that reason, it's pointless to pay the penalty of an increasingly thick boundary layer all down the sides of your trailer, and then incur the drag penalty of vortex generators to create vortices right at the rear separation edges (where the vortices can no longer do anything to help you.)
If you're feeling so inclined, it would be nice to see what the effect is of placing the VG devices about 2.5 feet aft of the leading edges of the trailer sides instead of right at the rear separation edge.
In any case, as you've rightly pointed out you are likely to see much greater aero gains by cleaning up / streamlining other aspects of the trailer (the roof looked particularly "dirty").
Thanks for the info!... Maybe a project for later ☺️
Yeah, with aircraft, VGs are supposed to improve airflow across the surface of the airframe behind the VGs. That's why aviation VGs tend to be placed near the front of lifting surfaces, with the expectation that they will up the aero across the rest of the wing afterwards. In technical papers, I have read that the ideal placement was 20% of the distance back from the leading edge.
So following that theory, placing VGs at the rear of a land vehicle would only improve the airflow over the nonexistent vehicle body behind your trailer's rear end. Thus, no bueno.
I remain a little skeptical. I just read a technical paper on one of my favorite planes, the Cessna 208 Grand Caravan, which said that there is negible benefit from leading edge VGs on that plane either, because the wing already works about as well as it can for its intended kind of flying. They found only a 1.2% increase in airflow and lift at slow speeds under very limited, specific conditions. #NotWorthIt
But pilots of plenty other light planes swear by the VGs on their units. 🤷🏻♂️
The mpg gain will be extremely minimal at best. Drag per vehicle is complex and simply changing one item is highly unlikely to provide any appreciable ROI. However, for vehicles with huge handling issues, VGs can effectively cure a huge issue of woe. My RV could be a bear to handle, not only at freeway speeds but even at 40 mph in a crosswind. Two lane country roads were nightmare inducing. In fact, I bought it from a couple that were too scared to drive it because even a Ford Escape passing by would cause it to push to the shoulder then suck it back across the lane dividing line. Seriously, you would spend as much your driving time watching your mirrors for approaching vehicles as you would watching where you were going. They had thrown thousands of dollars into suspension upgrades with little to no improvement and were relieved to sell it, even at a huge loss. (no need to laugh, it is a Class A on a Workhorse Chassis a.k.a. a Chevy P series frame and well known for this issue.) A series of these around the rear of the coach extends the air flow past the vacuum bubble following the rear so that passing vehicles have almost zero effect. What used to be a two-handed, white knuckle driving nightmare becomes a single handed, easy to drive vehicle.
So, if you have a vehicle or trailer that gets pushed around by passing vehicles or crosswinds I'd seriously be looking into these (provided you don't have any chassis maintenance issues. These won't cure bad springs, tie rods,etc.) If you drive a tractor/trailer or heavy straight truck over 100,000 miles/year I'd consider them.
The science behind vortex generators? czcams.com/video/9Whd_KnsLKE/video.html
Well my ROI wasn't bad considering I printed them myself... Total cost maybe 10 bucks lol.
After completing the video, I realized that for the final test, my wife was with me. So accounting for my wife's weight (about 125 pounds) I figure the air tabs saved me at Best 0.3kwh of energy.
Also, had I been traveling at a higher speed, I may have seen more improvement.
In any event, they cost me next to nothing, and they look interesting lol
A for effort Ed, great idea for testing...curious to see the next ones
Thanks!
i'm a sucker for all this aerodynamic stuff so it was definitely interesting to see your little experiment. :D
what about "trailer tail fairings"? did you consider or tried those??
czcams.com/video/BvULjXE3O5o/video.html
Definitely considered it .. just never got around to trying it.
We ended up crossing the continent like this. Went great!
Just came across your video. I’m trying to find a way to improve aerodynamics for my set up. I’m more traditional, Tundra pulling a 26’ RV. Speed of course is the biggest factor but would like to keep up with traffic. I have a trifold bedcover on my truck, I want to try and angle the first part up at about 30 degrees to see if that would help get the air over the trailer. Those air tabs have been out a long time and I think if they worked would have been adopted by all the big trucking companies but have not.
Yeah, I think the most they may have helped was about 0.3kwh of energy savings.
I calculated that based on the extra weight I carried on the final test (my rather light weight wife lol) ... She wasn't with me on the "before" test.
I may have seen slightly better improvements at higher speeds though. 🤷
If you have to buy them, they're not worth it. But if you can 3d print them like I did, then why not.. can't hurt.
Make a truncated boattail from Coroplast, tape and some angle brackets, or even hinges to make it foldable. Commercial trucks use them. Will save your minimum 15% and costs next to nothing. You'll also be the dad magnet of the camping grounds.
Lol.. dad magnet.
I actually had fully intended to do that. But as we got closer to departure day, I decided not to bother.
I actually went to the hardware store specifically to purchase the needed supplies and decided there that it just wasn't worth the headache. Plus there's a bunch of stuff hanging off the back of the trailer getting in the way. Not to mention the tail light situation.
In any event, we're already 1000km into our trip, and things are going pretty good as is 😁
@@edsgarage001 Love it, go explore. I camp too with my EV but we sleep in a tent and we eat in diners. Wouldn't waste my precious KWh on a trailer. Might get a rear mounted luggage box one day.
This was in part a vacation, in part a CZcams series, and in part a point that I wanted to prove (that it's entirely possible to do this 🙂)
Rather like cycling into a strong wind and then turning round and heading back, high winds are not a zero gain. To get the same result on a windy day means they are doing something. Perhaps experiment with teh locations too. Were they too close to the trailing edge, hence not allowing vortex to form, or is that the recommended location?
According to the website that sells the same things, this was the recommended location.
I did the test in both directions. I just don't think I was going fast enough to see a difference.
All the tabs I have look like they are going the other way. Maybe not. Just looked backwards to me. Good luck!
Checked the air tab website... This is apparently correct
What about an airline on the car to divert the air completely??
That would be a lot of work lol
Is that solar panels on the front of the trailer?
Yessir! 300 watts on the front and 200 watts on the top. 3kWh worth of battery inside 😊
*glances at wife while making up a number for how much it cost*
🤣
Didn't cost very much
still runnning em?
Sure am, they would be a huge pain to pull off lol.
I think they're saving us 0.3 kilowatt hours per 100 km
@@edsgarage001 right on, about to add em to my machine and hope i get a gain as well
3d printing or buying?
If you're buying them, I don't think it's worth it tbh.
@@anotheryoutuber_ did you add them? any thoughts? I want to add them to my tesla model y and trailer lol. very similar to this set up
@@midnight121190 i did add them, i tried 3 varieties, they all had the same results albeit very small gains for my application and placements. if you are into backyard science have at it. just make sure you take as much data as you can, to assure they are helping and not hurting economy or stabilization.
the test loop was too slow. Try this at 70 mph instead of such low speed. what I hear tho is stability strong YES, mpg no.
Yes... You're right. I probably would have seen some improvement at higher speeds.
However I realized afterwards that they may have provided a slight savings, as on the final test my wife was with me.. so despite an extra 125 LBS (ish) I had the same result. So that equates to about 0.3kw of savings lol
Unfortunately... It's a little late to test it now, as I won't have a pre-install run to go off of. I'm not ripping them all off now lol 😆