I Finally Discovered The True Answer For The Purpose Of The Rear Wing On QV's

I guess I need to install one, I never drive below 80 MPH.

Doug

 

"So we can't really draw any conclusion on "Present vs Not Present on every car = Useful vs Cosmetic."
"
Yes, radios were optional as were all the items you mentioned - items that were not essential to the function of the car. The way I see it, is that by the same logic the wing was also NOT essential for the function of the car because it was optional. The Pontiac Firebird offered a hood bird option; the Ferrari 3x8 offered a wing option! https://i.pinimg.com/originals/c2/c2/52/c2c25228c4994a8aa08b5c04897b9c5a.jpg

 

Well, consider things like driver-adjustable traction control, suspension adjustments, turbos... all options on a Porsche, which may or may not be considered essential. Seat belts used to be an option. Antilock brakes are options on some motorcycles.

I mean - I think that we could all agree that an engine and wheels of some sort are essentials, but ground effects - even when they DO something, are often an option. Clearly the 308 wing isn't essential, as we have hundreds of them with and without, and one group isn't mysteriously running off the road or bursting into flames with regularity because they have or don't have a wing.... but, that doesn't just automatically mean the wing never had an intended purpose (nor what the purpose was, nor if it actually accomplished that goal.)

Consider the spare tire - is it essential? Not to me. Does it have a purpose? Yep. And for some, the only purpose is to have original equipment in the car for show points. Many modern cars don't even come with a spare... but that doesn't negate spare tires having a use.

 

Based purely on the rough CFD I did the wing would in effect only be noticable as improved cD (coefficient of drag) and result in slightly better mpg... However given the speeds it was most effective, seriously doubt that's any concern, it would also theoretically allow for a greater top speed in a given gear.

As small as these cars are, they have terrible rear air flow. The low pressure zone extends a good 8' behind the rear at 80mph. The 328 rear valance greatly improved that problem, the early diaper of the 308 made it worse.
A belly pan also improves the cD, yet is oddly not present.

 

It’s is a real effect, remember my deep front spoiler that some people called it a snow plow? Anyway this is my response to a guy looking for a data about spoiler: “For me, I don’t have a data but with my deep front spoiler, I can feel the way my car drove when I was going 150MPH, stable, lowered, and smooth, and this is a fact.

 

Let's have a seance so we can ask Enzo.

 

He probably didn't know (or care) if it had one or not.

 

This is super-interesting and (as usual) very well-written I knew the word "aileron" because my dad was a pilot so this makes perfect sense to me. I guess another interesting question would be what % of QV orders/buyers requested this option? I don't think I have ever seen a QV without one but generally the aileron tips me that is is a Qv so never really looked at it from the inverse - Anyway, very interesting - Nice work - Cheers

 

Yep, FUN thread!

 

Actually it’s Leonardo Fioravanti you want to ask who designed the 308 and many others and he’s still alive.

 

How about now, is this functional and does this have the down force effect?

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Enzo Ferrari's take on it?:

"Aerodynamics are for people who can't build engines."

 

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

 

So what did your simulations/tests show?

 

Wonder if any of the car magazines in the 1980s ran articles or comparison tests on various spoilers, wings, etc. that were being applied in the auto industry?

 

The Lancia Stratos had a similar wing at the back of it's roof line - Did that also do nothing?

The BMW 3.0 CSL "Batmobile" also had a similar wing at the back of it's wing - Did that do nothing? (I believe that wing has been shown to direct the air coming over the roof, down onto the rear wing)

CFD testing is pretty damned good these days, but as has sometimes been shown in F1, it is not always perfect, because it is essentially a computer trying to predict what it "thinks" the air will do - Sometimes the CFD testing and wind tunnel/on track results are not the same.

At the end of the day, as I have said before, without real World testing, in air tunnels, or on track with air pressure sensors, everybody is just speculating and guessing as to whether the 308/328 roof wing serves any real function or not.

We can go round and round and round, for the next 20 years plus arguing it (like we do with cambelt change intervals), getting nowhere. Unlike the cambelt "discussion" however, there is a way to get a final "black or white" answer about the wing - Carry out tests: The wing either does something (to some degree or other), or it does nothing whatsoever.

 

Yes, today CFD is very powerful and it has reduced wind tunnel time/cost significantly. Back in my day my job was developing and applying CFD codes to problems for DOD, NASA, and commercially as well. There wasn't much CFD applied to automotive aerodynamics back in the 70's and when the 308 was developed because there wasn't any CFD available for the most part and at the time what relatively simple CFD we did have stressed super computers to the max. The codes that were available were incapable of providing the detail required for flow simulation over a simple representation of a sedan. The point is that I understand the problem and the complexity to do it right.

The reason ask about the conditions of any simulation is because they make a difference.

If Ferrari was interested in drag reduction on the 308 where would drag reduction be realized? Easy way to find out if the rear wing has such effect would be to do a top speed run with and without the rear wing. Any significant drag reduction would result in a higher top speed. Total drag includes aerodynamic drag plus that due to rolling friction and can be found by Fd(lb) = 375 x HP/V(in mph). Now assume that the rear wheel HP is 200 and max speed is 158 mph. Fd = 474 lbs. If we could increase the pressure on the rear window area by just 0.1 psi, with that area about 290 sq" the drag would be reduced by 29 lbs to 445 lbs and top speed would increase to about 168, assuming rolling friction remained constant.

 

For trivia's sake: the aileron was invented by Alexander Graham Bell for the Aerial Experiment Association with Glenn Curtiss as a way to bypass the Wright brothers patent on wing warping. Just so you know...

 

We should be pleased that Ferrari trusted new-fangled aileron technology instead relying on wing-warping!

 

I don't know about that. Seems more like it took Ferrari 110 years to catch up with the Wright brothers.

Anyway, I think it's safe to say drag reduction wasn't the aim of Ferrari for the 308. The deep spoiler would be contrary to that goal.