A pillar guides

[JulianEdgar]

Originally Posted by Cd

Julian, I noted that your best results came from a 17 mm inlet.
I planned to use some thickwalled Coroplast ( 4mm ) and use the built in ribbing to direct airflow, but now see it will be far too small.
I could sandwich the Coroplast till I get the correct thickness, but I see you also had a smaller outlet diameter.
So I guess that won't work.

I tried lots of things. Only the aerofoil section extrusion gave good results.

I wanted to ask if the Gen1 Insight has raised channels along side the windshield like my Civic does.

Yes, 15mm.

[JulianEdgar]

Originally Posted by Vman455

Just one example, the 2020 Hyundai Elantra:

I wonder if on cars like the 2020 Elantra, there is a move towards getting more air over the roof and less around the sides? I'd expect such an approach to reduce A pillar trailing vortex strength, and with the very curved roof of the Elantra, you'd expect pressures to be low across pretty well all of it ie they'd be making use of a characteristic that otherwise is all negative (lots of lift forces).

As I said, nothing like that though in the tech literature - that I've seen anyway.



I've been looking at a few Hyundais and they do look aerodynamically very well developed (eg rear transverse muffler angled to act as diffuser on one model). Didn't a whole bunch of Audi engineers go to Hyundai a while ago?

[Vman455]

And, I think, the person who was running BMW's M group?

The nearest I've seen to any discussion of this is a passage in Scibor-Rylski where the author argues that elevating headlamps and taillamps on fins or protuberances, by restricting lateral airflow increases mass flow rate over the center of the body and thus the velocity.

I went out to look at my Prius last night because I couldn't remember, but sure enough it does have the raised edge around the windshield too. The next calm day we get, it would be easy enough to tape some coroplast along there and raise the edge and measure pressures along the windshield and A-pillar with the fairing at various heights to see if there's any variation.

[Cd]

Vman, could you also tape some tufts around the area as well ?
No need to photograph or video the results.
I'm just curious about what direction the air will travel.

When I did my A pillar test, I just slapped it all together in less than three minutes - and it showed in the results, since the coroplast piece bowed.

My parents have a 2012 Fit with deep ( rain ? ) channels, and i tufted the area at the base of the windshied.
The air just skips right over the channel, and goes for the side window like it's not even there.

Edit : Hey thanks for the link to the HotRod Camaro article.
That would be the one I was refering to.

The template thread is closed, ( I guess people are stepping on toes again ) but I wanted to mention that despite being a "tiny " tunnel, not having a moving floor or moving wheels, the results are still good.
Car & Driver did a test in a tunnel just like this one and got accurate results.
Looking at the photos, it appears to be that they used the DARKO tunnel.
I get A2 and DARKO confused a lot from pictures.

https://www.caranddriver.com/feature...mparison-test/

If anything, the results were actually higher than the published factory figures.
( Which I would think to mean that .201 might be pretty accurate. )
But I am just guessing, and know nothing about any of this.

I'd like to think that it is that easy to modify an old 1979 Camaro to almost the same cD as an E-V1 with just a few minor modifications.
Imagine if they took it even further and had wheel skirts and such !

[JulianEdgar]

Originally Posted by Cd

Vman, could you also tape some tufts around the area as well ?
No need to photograph or video the results.
I'm just curious about what direction the air will travel.

When I did my A pillar test, I just slapped it all together in less than three minutes - and it showed in the results, since the coroplast piece bowed.

My parents have a 2012 Fit with deep ( rain ? ) channels, and i tufted the area at the base of the windshied.
The air just skips right over the channel, and goes for the side window like it's not even there.

Edit : Hey thanks for the link to the HotRod Camaro article.
That would be the one I was refering to.

The template thread is closed, ( I guess people are stepping on toes again ) but I wanted to mention that despite being a "tiny " tunnel, not having a moving floor or moving wheels, the results are still good.
Car & Driver did a test in a tunnel just like this one and got accurate results.
Looking at the photos, it appears to be that they used the DARKO tunnel.
I get A2 and DARKO confused a lot from pictures.

https://www.caranddriver.com/feature...mparison-test/

If anything, the results were actually higher than the published factory figures.
( Which I would think to mean that .201 might be pretty accurate. )
But I am just guessing, and know nothing about any of this.

I'd like to think that it is that easy to modify an old 1979 Camaro to almost the same cD as an E-V1 with just a few minor modifications.
Imagine if they took it even further and had wheel skirts and such !

If the Camarao could achieve that Cd in any proper, full-size wind tunnel, I'll eat my hat. If it sounds too good to be true, it's because it is.

And in the Drag Queens article, note how they do not ever identify the wind tunnel - funny that. When I included that material in my book, I'd no idea the data was collected in a 'toy' wind tunnel.

[IRONICK]

The new Mercedes-Benz A-Class: Aerodynamics - Saving fuel the aerodynamic way ~ mercedes gla



The exterior mirrors and the low stepped height of the A-pillars reflect the fact that the work conducted in the wind tunnel was not just about optimising the flow conditions, but also about minimising wind noise. And in addition to aerodynamics and aeroacoustics, there is often another discipline to consider: in terms of water management too, the flow around the exterior mirrors and the A-pillars also has to be optimised in the wind tunnel in order to guarantee good visibility is maintained towards the rear and at the sides during wet weather.

[Cd]

Originally Posted by JulianEdgar

If the Camarao could achieve that Cd in any proper, full-size wind tunnel, I'll eat my hat. If it sounds too good to be true, it's because it is.

And in the Drag Queens article, note how they do not ever identify the wind tunnel - funny that. When I included that material in my book, I'd no idea the data was collected in a 'toy' wind tunnel.

Julian, I don't understand.
If "toy" wind tunnels give bad readings, then why were the results of the Drag Queens article either spot on, or even higher than the factory quoted cD ?

[JulianEdgar]

Originally Posted by Cd

Julian, I don't understand.
If "toy" wind tunnels give bad readings, then why were the results of the Drag Queens article either spot on, or even higher than the factory quoted cD ?

If tiny wind tunnels are all that is needed, why doesn't every car manufacturer in the world save hundreds of millions of dollars and not build huge wind tunnels?

There's plenty of tech literature around that shows the issues with small wind tunnels, let alone those without moving floors/wheels. I've cited it all here before, so I am not going to bother doing it again.

[Cd]

Originally Posted by JulianEdgar

If tiny wind tunnels are all that is needed, why doesn't every car manufacturer in the world save hundreds of millions of dollars and not build huge wind tunnels?

There's plenty of tech literature around that shows the issues with small wind tunnels, let alone those without moving floors/wheels. I've cited it all here before, so I am not going to bother doing it again.

And the cD figures from the DragQueens article - can you explain that ? ( The accuracy )

Yet another way to verify the cD of the Camaro would be to look at the cars' top speed, correct ?

Since this car was built for that exact thing, I would think you could do the math and find the true cD, or at least something close.

I would have to look back at the articles to see what horsepower the car ran at.

It ran at several tracks - not just Bonneville, so this would also be a good indicator, correct ? ( lakebed salt / lakebed dirt / landspeed track asphault )

The guy that owns the car is on Facebook etc. If that would be helpful.

[JulianEdgar]

Originally Posted by Cd

And the cD figures from the DragQueens article - can you explain that ? ( The accuracy )

Yet another way to verify the cD of the Camaro would be to look at the cars' top speed, correct ?

Since this car was built for that exact thing, I would think you could do the math and find the true cD, or at least something close.

I would have to look back at the articles to see what horsepower the car ran at.

It ran at several tracks - not just Bonneville, so this would also be a good indicator, correct ? ( lakebed salt / lakebed dirt / landspeed track asphault )

The guy that owns the car is on Facebook etc. If that would be helpful.

Let's go to the fundamental idea.

Are you suggesting that a tiny wind tunnel (without a moving floor or wheels) like you have shown can develop accurate data?

That goes against common sense (why would manufacturers bother building huge wind tunnels), goes against the steady increase in wind tunnel size and complexity as car manufactures have chased better accuracy, and goes against all the published technical literature on automotive wind tunnel design. I don't know of even one peer reviewed SAE paper that covers a full size car in a tiny wind tunnel.

I don't want to be rude, but if you want to gain good knowledge on a subject, at some stage you have to look at some decent sources for yourself. My library is covered for painting but, from memory, Low Speed Wind Tunnel Testing (Pope?) would be a good start.

As for the figures from the tiny tunnel - who knows? Maybe they juggled compensation factors, maybe they made them up, maybe they're all serendipitously correct?