Tested: vortex generators (AirTabs) on a Toyota Corolla

[TELVM]

Sadly most probably too large (at that size), too effective and too drag-inducing for automobile application. But man do they look cool .


The SA-160 is a cheap 'kit-car' aircraft. To keep the wings simple and easy to build they are 'straight' and lack any 'washout':



That however means potentially dangerous stall behaviour, as it is safest when the wing root stalls before the wing tip, and not simultaneously. Those weird VGs solve the problem by delaying wing tip stall and ensuring aileron control.

[MetroMPG]

Re: the Sienna...

Originally Posted by roflwaffle

What year is it? Even though any 90ish degree angle is good I'd say the older the better since some of the newer boxy stuff has unbelieveably low drag for what it is.

I talked to my bro & sister in-law tonight: I'll use their approx. 3 year-old Montana instead of my sister's Sienna (logistics easier). Not sure what the Pontiac's Cd is, but I'm guessing it's higher than the Sienna. I do know I'll have to remove the OEM roof racks to do the test. Fortunately the torx screws are on the outside, so it shouldn't be too hard to do.

[crexcrex]

There is no possible way that i can let the subject of air tabs be discussed over and over, the bottom line is that after three months of using Voretx Generators in all possible configurations.............they do not work period! they in fact apply down force and do not attribute to any significant gain in gas mileage.

three months of using vortex Generators tell me one thing and that is to let them use them on Delta winged aircraft as they have no place in the world of cars that are land bound..............

If you can visualize a mini gate attached to the vehicles turret, the gate may well allow some air and wind through the gate but the vortex generators actually block the wind and air from travelling smoothly and effectively over the turret.

When i finally removed the vortex generators one could litterally feel the down force previously applied by the vg's allow the rear end to run free and unencumbered by the mini fence.............

I am sure there are many here who will continue to play with vg's till such time they realixe that it induces drag rather than reduce it.If anything i have learned that vg's would be great on the sides of a truck trailer as it would reduce the amount of sway thus keeping the truck trailer steady.
I wish the best to those who keep trying with vg's. The vg's were applied to a crx, yes! the good old Kamm Back.

I have no furteher commentts on vg's i now consider the subject closed and leave it to those who feel that it may be of benefit to thier vehicles

[MetroMPG]

crexcrex, you're preaching to the choir. I happen to agree with your overall assesment of VG's, but the goal here is to present some quality data with some semblance of reliability & validity.

If we only offer subjective, anecdotal experience, it will simply be countered by someone else whose anecdotal experience seemed to produce the opposite results. Then we have a relatively useless "he said, she said" situation that won't help anyone looking for quality information.

[pugmanic]

As all of your data shows VGs are usefull in changing the direction of airflow, but in most applications this is of little use due to an increase in drag.

As far as I was aware the VGs on the Evo were used to direct air flow to the rear spoiler therefore aiding in the creation of down force, not to reduce drag.

[MetroMPG]

Hi pugmaniac - I think you're right about Mitsubishi's goal for VG's on the EVO. But they also reported a very small (Cd -.006) reduction in drag as well.

Renault also apparently achieved a small amount of drag reduction with fin-type VG's on the trailing edge of the roof of an ecomodded Logan sedan which they used in the Challenge Bibendum: http://ecomodder.com/forum/showthrea...cy-up-179.html

[moorecomp]

On 07-22-2008 crexcrex said this about his VG's -

Originally Posted by crexcrex

The buisness of airtabs is to sell you as many as you do not need, 21 is a case of overkill, 21 would be great for a semi! before i can comment re number of tabs on the roof how many inches at the widest point? I have seen them and not impressed i beleive that you will find that your drag will go up..............if i had the cash i would bet on it.

I made nine shark fin style for a crx and have installed them and used them and can feel the effect on the highway and city as the air rushes over the roof the fins divert the air down onto the glass and off the back............to reap the full benefits of the vortex generators i can only conclude that i will have to install a air wing.......not a spoiler.

I can only suggest that you check citroen the pro's on aerodynamics and arrive at your own conclusion.................speaking for my self i usually coast down this bloody hill each day. prior to using the vortex generators i would coast at 50 miles per hour and with them 60 with a head wind or not...........I made my own vortex generators and am satisfied.............bottom line is too may will cause more drag.

I am sure this entire matter is and will be open to debate.

Your typical vortex generators are four inches apart and one inch from the edge of the vehicles roof.

Now he says this -

Originally Posted by crexcrex

There is no possible way that i can let the subject of air tabs be discussed over and over, the bottom line is that after three months of using Voretx Generators in all possible configurations.............they do not work period! they in fact apply down force and do not attribute to any significant gain in gas mileage.

three months of using vortex Generators tell me one thing and that is to let them use them on Delta winged aircraft as they have no place in the world of cars that are land bound..............

If you can visualize a mini gate attached to the vehicles turret, the gate may well allow some air and wind through the gate but the vortex generators actually block the wind and air from travelling smoothly and effectively over the turret.

When i finally removed the vortex generators one could litterally feel the down force previously applied by the vg's allow the rear end to run free and unencumbered by the mini fence.............

I am sure there are many here who will continue to play with vg's till such time they realixe that it induces drag rather than reduce it.If anything i have learned that vg's would be great on the sides of a truck trailer as it would reduce the amount of sway thus keeping the truck trailer steady.
I wish the best to those who keep trying with vg's. The vg's were applied to a crx, yes! the good old Kamm Back.

I have no furteher commentts on vg's i now consider the subject closed and leave it to those who feel that it may be of benefit to thier vehicles

So were you confused then or now about VG's. If you could coast at 60 instead of 50, then you could at least increase your FE by longer EOC'ing. But we don't know, because you don't have any fuel logs.

VG's do not "produce downforce", they create a vortex or swirl of air, thus increasing the speed of the air and resulting in a decrease of air pressure, allowing the flow to remain attached. Low speed aircraft use them to maintain flow across the upper surface of the wing during high angle of attack flight. They are not used to smooth out the airflow behind the plane, like airtabs are designed to do in the case of a large square box truck that has alternating swirling vortices coming from the sides of the box (motorcycle riders know this well). Those vortices create a suction drag and by using the airtabs to force those vortices further aft of the box, the suction drag is reduced. Check out the videos from the Valdez Alaska Fly-In STOL competition sometime. Cubcrafters Carbon Cub tookoff in 19ft. and landed in 53ft.

CubCrafters: <font color="F1AB00">UPDATED!!!</font> CARBON CUB THE HIGHLIGHT OF THE MAY DAY FLY-IN AT VALDEZ.


The problem that people have here on EM is they use them in ways that are never going to do any good as far as FE goes. Mitsubishi has shown a slight increase in FE with all their extensive testing, the average joe slapping a few homemade VG's or airtabs here or there will probably never see a measurable improvement.

A&P and Hypermiler

[eco_generator]

Interesting. Even with a net zero +/- in fuel effeciency... I'd consider a clean rear window a plus! Especially if you don't have a rear window wiper.

[laser117]

I have a Dodge Caravan that I tow with occasionally, but when I tow, it's for 900+ miles. If airtabs would work in that situation, to reduce turbulence, improve stability, they would be worth the investment. If I got an increase in mileage, that would be awesome too. I'm already towing a 3000lb box. If one can do *anything* to help this situation, I think it might be worth it.

I think putting them on cars that are already small, light, and aerodynamic is missing the point. Someone said, and maybe it was this thread, that VG were a bandaid for bad aerodynamics. I tend to agree. Then let's test them on vehicles that have bad aerodynamics.

Not that I'm saying that what was done here isn't important...the information we are gathering from this thread is definitely useful. We are learning that there's no point with small cars...but how about continuing the thread with a redefined focus, or determining that this thread should more or less end at this conclusion, and subsequent testing with larger, less aerodynamic vehicles will resume at a new thread? You know, instead of declaring VGs a failure for land based vehicles, or anything smaller than a semi-truck.

I'd think that F series trucks, cargo vans, and mini-vans/SUVs might benefit from this...especially while towing. I guess the people that own those vehicles aren't normally "gas crazy", but let's face it...those people spend more money on gas than the "green people"...
It's just not always practical for people to drive the little Civics and Metros. I actually *use* my van. I'd just like to optimize it. Every little bit helps...but a 4% gain on 15mpg isn't that much, and I understand that.

As gas prices go up, maybe people like me won't be such an oddity, and that 4% becomes more significant.

[crexcrex]

Firstly, metrompg dosen't know how to read, in a nutshell i stated that you can arrive at your own conclusions by experimentation, i do not endorse the use of Airtabs which is a knockoff from citroen.

Please note that the increase in coasting distance was not due to the use of Vortex generators but to the reduction of the CRX weight, i do agree that there MAY be benefits truck trailers and possibly long wheel base vehicles, Rv's and towed trailers. I certainly would weigh the pro's and cons before you purchase one single Airtab.
Unlike Metrompg we do not all drive Metro's there are some of us who drive vans trucks etc related to buisness. I have not seen a Metro hauling commercial trailers.
Bestof luck re mods.