Do air tabs work?

[Arragonis]

Originally Posted by euromodder

Nobody on here has been able to proof they do improve FE, and it wasn't for lack of trying

I still think they could work, but not in the usual massively/truck-sized variety on a regular car.

Something more subtle might do the trick. Renault / Dacia had them on the rear roof line of their eco-Logan.

OK, but Dacia probably had some wind-tunnel time via Renault to try things out ?

We know there is a return with some people from a grill block (although both you and I have tried these and not seen a significant difference - but that might be the difference in Euro vs US driving conditions - long cruises and journeys in the US vs. our more busy and choked roads).

We have seen coast downs with boat tails which seems to suggest an improvement and with wheel covers (front and rear), new noses, wheel spats, mud flaps removal or reversal. Even some differences with mirrors folded and removed vs not.

The coast downs with tabs suggest minimal effect and threads testing them on cars longer term show no difference at all as far as I can tell, or whatever difference is recorded could well be inside an error range.

So at the moment we have to say at best "maybe" or it has "potential", but on a firm this-makes-a-firm-difference basis we have to say "no".

@Neil - I would love to see those instructions and for someone to do some proper testing having followed them.

[dcb]

Originally Posted by Arragonis

We know there is a return with some people from a grill block

The difference is that the barriers to implementing a grill block are about non-existant. I think the first one was wet newspaper or something, any sort of material can be bodged into a grill block (of varying durability), you can prototype one with coloured duck tape, or even cram neglected beanie babies into your grill.

Originally Posted by Arragonis

So at the moment we have to say at best "maybe" or it has "potential", but on a firm this-makes-a-firm-difference basis we have to say "no".

VG's for fuel efficiency are surrounded by mystery, or bullocks if you prefer. There is no end to the number of things you could be told you are doing wrong after trying them, it isn't well defined how it is supposed to be helping car efficiency. There simply is no defined theory as it relates to efficiency or it's application. The potential here seems not worth mentioning in the "I think someone else should try this" sense, what you do with your own time is a different matter.

Originally Posted by Arragonis

@Neil - I would love to see those instructions and for someone to do some proper testing having followed them.

I'm confused, you don't think these other people did proper testing? On what basis?
Google Custom Search

Can you properly define proper testing of vortex generators? Can you also define proper testing for non-existence of invisible pink unicorns?

[Arragonis]

Originally Posted by dcb

Can you properly define proper testing of vortex generators?

A-B-A, of which your search picks up quite a few I thought maybe Neil had something new. Maybe not.

Picking through the first page of results at random, nobody seems to show a measurable effect on FE, certainly not the "riches and world peace" claimed by the makers. The MIRA test linked in one of the posts seems to show about 2.8% improvement on a truck.

Originally Posted by dcb

Can you also define proper testing for non-existence of invisible pink unicorns?

Heretic...

EDIT - The MIRA test appears on the Airtabs website too. But from memory I haven't seen any ParcelFarce trucks with tabs on that I can remember. Going to track one down and photo it.

[u.steinlechner]

Hi,
at the wheelhouse, I test a special version of vortex generators.
The goal was to improve the airflow at the wheelhouse.
In the windtunnel measured, the drag was not reduced by vortex generators, but the balance (lift/downforce) between the front and rear axis changed.

Ulrich

[oldtamiyaphile]

Originally Posted by u.steinlechner

Hi,
at the wheelhouse, I test a special version of vortex generators.
The goal was to improve the airflow at the wheelhouse.
In the windtunnel measured, the drag was not reduced by vortex generators, but the balance (lift/downforce) between the front and rear axis changed.

So did they give you positive or negative lift?

[suspectnumber961]

I asked a guy who has some on a light plane about any mpg gain...said there was none...but they did result in a lower stall speed...which is why they use them on planes. They allow better control at lower speeds.

[u.steinlechner]

Originally Posted by oldtamiyaphile

So did they give you positive or negative lift?

Hi,

here is the answer:

the aritabs were not used at the rear edge of the car, but in front of the wheelhouse.

So this values are not to evaluate Airtabs as the intended use case.

CW Widerstand drag
CA Auftrieb gesamt lift
Cav Auftrieb vorne lift front
Cah Auftrieb hinten lift rear


Serial state, Serienzustand
speed 140 km/h
CW 0,323
CA 0,0402
CAv -0,0223
CAh 0,0626


Xanon aerodynamic bumper with vortex generators
speed 140 km/h
CW 0,2971
CA 0,0256
CAv -0,1053
CAh 0,1309



Xanon aerodynamic bumper without vortex generators
speed 140 km/h
CW 0,2961
CA 0,0213
CAv -0,097
CAh 0,1184

Ulrich

[undeRGRound]

Nice Find, this thread

[undeRGRound]

Originally Posted by u.steinlechner

Hi,

here is the answer:

the aritabs were not used at the rear edge of the car, but in front of the wheelhouse.

So this values are not to evaluate Airtabs as the intended use case.

CW Widerstand drag
CA Auftrieb gesamt lift
Cav Auftrieb vorne lift front
Cah Auftrieb hinten lift rear


Serial state, Serienzustand
speed 140 km/h
CW 0,323
CA 0,0402
CAv -0,0223
CAh 0,0626


Xanon aerodynamic bumper with vortex generators
speed 140 km/h
CW 0,2971
CA 0,0256
CAv -0,1053
CAh 0,1309



Xanon aerodynamic bumper without vortex generators
speed 140 km/h
CW 0,2961
CA 0,0213
CAv -0,097
CAh 0,1184

Ulrich

Your "wishbones" are installed backwards

That looks to be a functional opposite of a version I found a few years ago on the interwebZ. I'd be curious to see a comparo of the airflow patterns forwards and backwards...

[u.steinlechner]

Originally Posted by undeRGRound

Your "wishbones" are installed backwards

That looks to be a functional opposite of a version I found a few years ago on the interwebZ. I'd be curious to see a comparo of the airflow patterns forwards and backwards...

Hi,

there are different concepts for vortex generators.

See, how "airtabs" work:

Airtab UK > Airtab Information > What are Airtabs?

Ulrich