308 rear spoiler (wing)

This is a really interesting old thread - wondering if anyone has put the 3D model through a wind tunnel software over the last couple of years?

Cheers!

Ruben

 

I found a local guy who has a portable 3D scanner and am working on getting a true image. Then we have some fun.

 

Very interesting reading! To me it makes the most sense to ascribe the existence of the "spoiler" as a drag-reducing device...however... making such an item optional (at extra cost in Europe) and its presence on so many other cars of very different design, makes the whole idea appear to be more of a marketing gimmick than something the designers came up with, based on good aerodynamic engineering practice, followed up by wind-tunnel testing! Not to mention the likely vast difference in effect on the GTB vs. open targa-top GTS versions of the same car, but no change in spoiler design or placement.

I do agree that turbulent air in the open cockpit of the GTS is very minimal, though. Whether this is due to the basic design or an effect of the small lip at the top of the windscreen on the GTS is hard to say, but it probably helps or at least doesn't hurt! I also think that with the targa top off it doesn't hurt to have the door glass raised, especially at higher speeds.

I will keep an eye on this thread in the hope that some good, reliable data is eventually posted. Especially if some original design insight by Pininfarina is revealed!

My thanks to all of you with "too much time on your hands"...

Cheers, Rich

 

I’m updating this post to add new information. This article specifically lists the Ferraris by model that where some of the first cars to incorporate the Kamm tail. Listed is the 250 GTO
https://en.m.wikipedia.org/wiki/Kammback

 

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Kami effect?

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Yes, hey Mike. If I remember correctly Kamm tails are a lip at end of car followed by a flat back surface. A downforce spoiler must be behind the vehicle (example F1 car). It looks like this might be a combination of both but the picture is cut off at rear.

 

I see! Also reminds me of the BB12 Boxer.

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Based on page 84 left column of IL Cavallino Nel Cuore… as used on the Boxers…

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" Who can forget this baby?"

I had a good friend who bought a Superbird back in the day and claimed he bought it because he was always forgetting where he parked his car; the wing made it easy to see! Of course, today that car is a several hundred-thousand dollar car rather than a 4800 dollar car.

Re the 3x8 spoiler - The area behind the 3x8 rear glass (backlight) is similar to the 1968+ Dodge charger. https://st.hotrod.com/uploads/sites/21/2019/02/003-stornant-1969-dodge-charger-rear-three-quarter.jpg

Mopar discovered that profile adversely affect aerodynamics in their Nascar racers and modified the backlight area thus (look at the rear window, not the big wing):
https://www.wallpaperup.com/uploads/wallpapers/2014/10/25/493339/3848711f9d8d9a6bdfe2a287e22134ee.jpg

It seem logical that Ferrari found the same aero issue at the car's top speed and determined (hoped?) that the small wing would reduce/eliminate the adverse affect.

 

A Kamm tail

Without the rear spoiler would be closer to true Kamm Tail like on an option less stradale Stratos

rear tail spoilers on Kamms were often added to primarily reduced lift rather than drag. Typically spoilers on kamm tails induced drag.

There are endless variables, you can significantly alter the aero characteristics on majority of the rear of the vehicle buy changing the front profile and section of the front. Even vortexes off the side mirrors and affect the rear airflow….

vortexes can be a detriment if not managed or an optimization if strategically placed.

then there are the styling, trend and fashion elements to consider…even ferrari isn’t immune to. Ever look behind the front grill of a 348 or 355 to see where the air goes?

 

Dr. Kamm original tail had no spoilers. It was focused on drag reduce to “fool” the airflow by abruptly cutting off the bodywork detaching air from the surface. He created a geometric formula beginning from ithe 30’s of the Kamm tail

You can put spoilers anywhere, front, rear, side dive planes to create localized reduction in lift or collectively to add downforce. They put spoilers on wipers to keep them from lifting at elevated speeds

Without the rear spoiler would be closer to true Kamm Tail like on an optionless stradale Stratos

rear tail spoilers on Kamms were often added to primarily reduced lift rather than drag. Typically spoilers on kamm tails induce drag.

There are endless variables, you can significantly alter the aero characteristics on 3/4 of the rear of the vehicle buy changing the front profile and section of the front and not touching the rear. Even vortexes off the side mirrors and affect the rear airflow….

vortexes can be a detriment if not managed or an optimization if strategically placed to aid the rear spoiler.

 

Wow, talk about a long winded thread. I personally never questioned so deeply the purpose of the rear wing as it seemed fairly obvious that the low pressure pocket that forms behind the rear window would cause a turbulent rotor and the wing was put there to arrest it and smoothen the flow across the rear section of the body. To add them as just a styling gimmick doesn't sound like Ferrari. But in regards to smooth vs textured I believe that they manufactured the smooth ones for GTB's and the textured ones for GTS's before they knew how much more popular the GTS was going to be than the GTB so they ended up with WAY too many smooth wings and just started putting them on GTS's. That sounds like Ferrari.

 

"Wow, talk about a long winded thread."

Heck, if it was an oil or cam belt thread it would barely be getting started!

 

Hi Paul,

It's all a scam. A hoax. Poppycock. Or whatever you call it. You guys are making the matter way much too intellectual, or theoretical: the rear wing serves no purpose at all, if only aesthetics.

As said so many times before (pardon me if I'm getting slightly boring...) I have two 328s, a February 24th, 1989 GTS WITH a rear wing (= # 80515), and an April 5th, 1989 GTB WITHOUT a rear wing (= # 81085).
There is absolutely NO DIFFERENCE whatsoever in the running temperatures of the two cars, EXCEPT that the one without the rear wing (the "B") tends to run slightly cooler than the one with it (at least, according to their gauges)

It's just a styling gimmick, nothing more.

Rgds

 

Who says the aerial was for solely cooling?

Here’s is what we do know through pininfarina documentation.

boxer 365BB was the first production to be tested in pininfarina’s then new wind tunnel. It had a roof aileron.

77 pininfarina 308 Gtb Aerodinamico better know as “millechiodi” was developed in its wind tunnel “to further improve its aerodynamic qualities” also added an roof aileron

Nearly all of these appendages were later adapted to 208 turbo, 308 qv and 288s in various forms but identical in concept

Additional cooling modifications on millechiodi comprised of split front and rear bumpers and a floating cap hood over cut out of the standard decklid. This was before the production cars had incorporated a full width wide deck grill for cooling

As an note, here is dallara’s aero test of an early stratos, it too had tested a roof aileron in the pininfarina tunnel though Bertone designed vehicle. This aileron would later be refined to be raced on gr5 and gr4 cars and became an option for the stradale production stratos’s.

But since we are here on Fchat, let’s all take your observations on your cars temperature gauges as gospel… that’s good enough for me

 

As I have already written a number of times in the past on threads about the same matter, there is also documentation saying that the roof spoiler on the 365 BB (at the time still called the "Superberlinetta") was introduced to solve a problem with a stagnant boudary layer above the engine hood, which was hindering the dissipation of the hot air from the engine compartment.
If the roof spoiler was indeed serving a purpose on 3x8s, would it then have remained a "paying option" on euro cars, right up to the end of the 328 production?

Rgds

 

Now what’s the name of the effect does this car has?

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Agreed. Even though mine came with one originally, I intentionally left it off during the restoration/repaint. An option I would have probably passed on when new, although it's really insignificant to me overall. Less is usually better in my opinion. US federalized marker lights removed too. I also left rockers body color (mine had previously been repainted this way before I acquired it) as opposed to black (84/85s) but I understand perhaps this was optional too (?). Regardless, I like it better.

Same car, 55057, eight years apart. The Rosso Corsa looks different but it's not. Correctly repainted, just the lighting/different cameras.

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Except that my 85 GTB QV came from the factory cam with a textured one. Maybe I have the only GTB with a textured one. I knew it was special.

 

Who’s says there was a problem… was there a problem with the original xwx 14 inch wheels and tires when the factory had a 16 P7 optional upgrade?

 

Could it be drag or rear lift reduction measure (improving flow to the rear deck trailing edge), which would not be directly apparent to a customer cruising at 55mph?