Reducing drag on old-shape sedans (notchbacks)
 

1) M_a_t_t, this one is for you!

2) For people following the Aerohead / template debate, as far as I can tell, this video covers how Aerohead thinks the aero of all sedans behave. (Primarily, because back in 1987 - the year of the textbook Aeroheads most often cites - this is indeed how aero on sedans was.) But things have changed...a lot. So don't use this video to modify modern-shape sedans that have attached flow.

https://www.youtube.com/watch?v=ea8FFmbYams

Where/what is that??
wait.. are you aerohead?
now im really confused..

following the Aerohead / template debate

Where/what is that??

Have a look around.

this video covers how Aerohead thinks the aero of all sedans behave.

wait.. are you aerohead?

Nope. Perhaps I should have said: as far as I can work out from what he posts here, Aerohead appears to believe that the aero of all sedans behaves as in this video on old shaped cars.

1987 - the year of the textbook Aeroheads most often cites

now im really confused..

Aerodynamics of Road Vehicles, 1987. Aerohead has repeatedly said he has not read any more recent aero textbooks.

When I got the notification on my phone I did think "finally, something that I could more directly apply" :D

I was thinking I could just use that adhesive spoiler and run it along the edge of the back window/c-pillar.

I hadn't though of raising the spoiler either. Do you think the angle of the spoiler matters? The stock one on my car points a little toward the front of the car, but if I'm making risers I could probably just account for that.

Yes, when I ran across the drag % details for each modification to VERA I figured that I'd better do a video! I used VERA as a role model for my first aero car modifications back in about 1989.

For separation edges? You could do that - easy and it would look fine - but I'd test with cardboard first.

It might look odd but perhaps have the spoiler top surface tilting the other way (ie downwards towards the rear) - like a hatch rear extension to reduce wake area?

Not that date specifically, but in the late 1980s yes, a huge amount changed in airflow patterns on sedans. Basically, we went from separation occurring at the end of the roof (sometimes with reattachment on the trailing edge of the boot/trunk, but often not), to largely attached flow down the rear window and onto the boot/trunk lid.

In turn this dramatically changed:

1) the main cause of rear lift

2) drag coefficient

3) how rear spoilers work


Old shape sedan (1986):

https://d3lp4xedbqa8a5.cloudfront.ne...odore-vl-2.jpg

New shape sedan (1988):

https://d3lp4xedbqa8a5.cloudfront.ne...ommodore-2.jpg

Even newer shape sedan (2013):

https://carimages.com.au/6Gw6YT_rq4P...re-sv6-531.jpg

Notice the change in rear window angle and C-pillar curvature.

So yes, basing your understanding of airflow patterns on sedans on a 1987 textbook is highly problematic.

Can we cast that in the third person?

The :) was for the over-specificity.

For me it starts with the first four generations of the VW Jetta with it's raised rear decklid. ....in 1979.

I might be able to just flip it around. If the angle isn't quite right I could probably just adjust the riser for a different angle. Or I could just remove the spoiler and play around with the pitot tube. How do you adjust the angle on your pitot mount?

I think the "old" sedan looks the sharpest. I think my Fiat is one of my favorites in the looks department.
https://ecomodder.com/forum/member-m...728-193858.jpg
https://ecomodder.com/forum/member-m...11117823-n.jpg

I don't think I have ever driven an old Fiat, but I remember watching them at race tracks do very well indeed. An X19 is on my list when someone gives me a lot of money and says, "Buy cars!". (My second car was an Alfasud Ti, so I kinda understand the era.)

I adjust the angle of pitot tube by either adjusting the angle bracket at the pitot tube itself or at the suction mount. But I'd be assessing different drag values of a modified spoiler with the throttle stop technique, not the pitot. Pity you don't live around the corner, because it'd be a really interesting test to do, I think.

I am exactly the opposite--to me, the old shape looks clunky. Give me a quasi-fastback, modern sedan any day. Something like the new Sonata; not the best from the front, but just stunning from the rear:

https://besthqwallpapers.com/Uploads...gray-sedan.jpg

I thought it interesting that Scibor-Rylski argues that aerodynamics and styling follow a natural progression toward forms that are both more aerodynamically sound and more aesthetically pleasing.

I agree on the throttle-stop testing for the spoiler change.

Some people just have poor taste I guess.
https://thumbs.gfycat.com/EthicalUni...restricted.gif



I was thinking of testing for a wing with the pitot tube I think. The riser's shape shouldn't matter since it should be in separated flow correct? Maybe the end pieces would be more important since they are closer to the separation point on the side of the car?

Due to the popularity of its Soviet copy, which had been available even in my country, I would never actually expect an American to drive a Fiat 124 sedan.


Sedans with a fastback-ish design look quite pointless to me. A full-sized hatch would increase its practicality and eventually compensate a little the decreasing availability of station-wagons.

Or eventually render it easier to convert them into some sort of station-wagon :D

Do you mean an actual Fiat opposed to the copy, or just the car in general? What would be so odd? They weren't sold in high numbers here anyway and that makes them kind of rare in the U.S.

I am more used to the Soviet copy, so even the original seems quite surprising to see it driven by an American. Not to mention Fiat never having been so popular among Americans in general. But anyway, it's not really a bad car for its age.