Vertical plate on rear body work

[rayce13]

Watching F1 and dreaming about what to work on for the car this winter and wondering about a vertical plate along the spine of the rear body work. It appears that to varying degrees the F1 cars have a 2-4" (less on Red Bull, more on Ferrari) vertical plate coming out on top of the air intake all the way to the back down the centerline of the car. I assume this increases lateral air resistance in turns and smooths the air flow but haven't been able to find any definitive information.
Any thoughts on what function this piece serves and benefits for our cars?

[Pop Chevy]

I think the Radon uses one. Dave W uses one on his Citation. Don't really know the purpose though. Great place for sponsors name ?

[DaveW]

I think the Radon uses one. Dave W uses one on his Citation. Don't really know the purpose though. Great place for sponsors name ?

The theory is that the fin creates vortices (spinning around a mostly longitudinal axis parallel to the fin and the bodywork) aft of the roll bar which help keep the air attached to the body and smooths its flow to the rear wing.

[Northwind]

It doesn't hurt when the car gets really sideways either. It acts like a vane on an arrow.

[Steve Davis]

Russ,
You might notice Dave's response of "smooths its flow to the rear wing". ! REAR WING !. At the speeds we run it would have negligible effect, but it seems to work pretty well above 150 MPH... if you can get there. I can't seem to get much flow to *MY* rear wing no matter how much I smooth the flow .

However, it does look decently cool on SOME cars and provides some rigidity to the rear bodywork (see a Vector rear bodywork - small fin, but ....). FWIW, I tried a fin last year on my car. Net result - lots of hassle - no positive improvement in any area that I could determine. Now gone.

In short - it probably won't HURT you and it might provide some good entertainment over the winter .

Steve, FV80

[Steve Demeter]

If needed it's size can be tweaked to put the aero center of pressure where you want it. If you are THAT smart to make sensible use of it, which I am not

[Ian Lenhart]

Did someone say fins.

[Tiago Santos]

Fins and a raised nose. The most F1 inspired vee ever?

[Purple Frog]

Interesting that both the 2011 and 2012 F2kCS champions had fins on the rear bodywork.

They also had intense preparation.

[Amon]

It looks like they used some Citation side pods....I wonder how that would
do at Road America ????


Mark

[Jim Nash]

Nice work Ian! I saw your car at RA (that's the nose of my car behind you) but never made it over to check it out. Hopefully I will have another chance.

Jim

[Neil_Roberts]

Engine cover fins first appeared on all of the 1994 Penske Indycars in order to hide, at least in side view, the giant intake plenum that the Mercedes pushrod engine required. All of the Penske cars had a fin installed so that it wasn't possible to tell from a distance that the pushrod engine cover was taller and wider than the one for the standard engine.

Many Indycar teams copied the fins without knowing that, and immediately discovered that they added a lot of useable signage area area that could be sold. That's why the engine cover fins persisted long after 1994. It's not about aero.

[Steve Davis]

Did someone say fins.

That is some absolutely BEAUTIFUL glass work. And VERY F1'esk. How come I've not ever seen this car before. Did you only run it ONCE at Road America? I presume it started life as a Vista Bushwacker?

How'd it do?

Sure like to see it in person some day.
Steve, FV80

[Ian Lenhart]

Nice work Ian! I saw your car at RA (that's the nose of my car behind you) but never made it over to check it out. Hopefully I will have another chance.

Jim

The credit should go to my brother Tad since it's his car. I can only take credit for the graphics. The chassis is equally impressive. It's a work-in-progress (bodywork needs molds - racing using the heavy plugs, find some horsepower, fine tune setup, etc.) plus it's been a learning curve going from FF to FV. It's great to see all his work finally pay off. My opinion is a bit bias, but this is the best looking Vee.

Ian

[rayce13]

Thanks guys. I appreciate it and think its probably not worth hacking things up on a 100mph FV!! I will probably work on some wheel covers instead

[Steve Davis]

... I will probably work on some wheel covers instead

Hmmm... WHEEL COVERS ... Now THAT'S an idea with some merit!

Steve, FV80

[glenn cooper]

Did someone say fins.

My Pinewood Derby car from '71 looked just like that!

[Amon]

My pinewood derby car from the early 70"s had a rear fin on it!!

[Neil_Roberts]

Of course, tailfins aren't really a new idea.

[asw]

I think the Radon uses one. Dave W uses one on his Citation. Don't really know the purpose though. Great place for sponsors name ?

It improves the yawing moment of the car. You can increase its functionality by changing its shape and size depending on the form of your car especially the rear end. Flow to the rear wing is one of them...

[DaveW]

Russ,
You might notice Dave's response of "smooths its flow to the rear wing". ! REAR WING !. At the speeds we run it would have negligible effect, but it seems to work pretty well above 150 MPH... if you can get there. I can't seem to get much flow to *MY* rear wing no matter how much I smooth the flow .

However, it does look decently cool on SOME cars and provides some rigidity to the rear bodywork (see a Vector rear bodywork - small fin, but ....). FWIW, I tried a fin last year on my car. Net result - lots of hassle - no positive improvement in any area that I could determine. Now gone.

In short - it probably won't HURT you and it might provide some good entertainment over the winter .

Steve, FV80

In addition to the aero effect, if you look at mine (photos below), it is also a tunnel to evacuate hot air from under the rear bodywork. Without this tunnel, the hot air was (at least partially) trapped around the engine. There was a significant improvement in cooling this year due in large part to this tunnel. Cooling is the main reason I added it.

[asw]

Nice work there, Dave.

Your's have a thick section to it and the low pressure inside there surely helps suck all the hot air out, however, let me ask you a few questions

- Has your top speed been affected?
- How is your rear end down-force doing after that change?
- Have you noticed any thing noticable?

[Bob VanDyke]

Of course, tailfins aren't really a new idea.

While the Marmom Wasp was probably the most aerodynamic car in the first Indy 500, the number plate wasn't part of the package. The car numbers were assigned by the date the entry was received and, to help with scoring and to make it easier for fans to identify the cars, they were required to have number discs located directly behind the driver. Also to aid the scorers, cars numbered 1-10 had to have the number on a red background, 11-20 on a blue background, 21-30 on a black background and all other cars had to have the number on a yellow background.

End of pedantic history lesson.

[DaveW]

Nice work there, Dave.

Your's have a thick section to it and the low pressure inside there surely helps suck all the hot air out, however, let me ask you a few questions

- 1. Has your top speed been affected?
- 2. How is your rear end down-force doing after that change?
- 3. Have you noticed any thing noticeable?

1. At the same time this was 1st run, I also had a fresh QSRE rebuild on the engine that has more power than it had originally from 2009-2011. So my top speed is significantly better (~2-4% at high-speed tracks) and the vent's effect on that is therefore unknown. To put this in perspective, frontal area is unchanged, and no one I have run with this year has had better top speed than me.
2. As far as I can tell, rear downforce is essentially unchanged from last year. I still have the same balance front-rear with the same wing settings.
3. As I said in the previous post, cooling is noticeably better. In 2011, in the race at Mosport when the ambient was ~100F, coolant got up to 205 to 210F while running, and oil temperature exceeded 280F. At NJMP this year with slightly higher ambient, the maximum coolant temperature was ~195F while running, and oil temperature never exceeded 270F.

I did install an additional small oil-air cooler in the return line to the oil tank at the same time, so the oil temperature decrease is not all attributable to the vent.

[Steve Demeter]

Is it attached by "adhesion to the body work" or are there mechanical fasteners in there as well?

I am thinking..... need a winter project.

[DaveW]

Is it attached by "adhesion to the body work" or are there mechanical fasteners in there as well?

I am thinking..... need a winter project.

If you look closely at the 1st photo in post # 21, you can see the aluminum angles used as bracketry to rivet it on. Photo of angles on main engine cover below. I wanted to make the installation easy and light, so no body filler or adhesives were used.

[asw]

Yes, some interesting work there, Dave. Glad to know its working out for you from a cooling point of view.

What is next? A new front wing? A new diffuser?...

[DaveW]

Yes, some interesting work there, Dave. Glad to know its working out for you from a cooling point of view.

What is next? A new front wing? A new diffuser?...

The front wing (same profile and size that I ran in 1988) will remain the same. We've never found one with better downforce/drag and consistency than that.

The rear wing also seems to have a good downforce/drag ratio.

And the diffuser is working well.

So no new aero for next year.

[lenhart05]

That is some absolutely BEAUTIFUL glass work. And VERY F1'esk. How come I've not ever seen this car before. Did you only run it ONCE at Road America? I presume it started life as a Vista Bushwacker?

How'd it do?

Sure like to see it in person some day.
Steve, FV80

Yeah, the body has been almost a two year project which including doing the front end twice to get the authetics right. This fall at Road America was it's first race, after a quick shakedown last fall at Blackhawk. It started out as a later model Vista. Thinking about it now, the body should fit all predators and vistas that shared the same original bodywork. The long side pods, and much of the rear cover, is original.

As far as how it did, I wished it did better. After 14 years of formula ford, I'm finding out that I'm way behind the curve in learning 50 years of FV knowledge.

Tad

[Steve Davis]

Hope you're making plans to bring it down to Roebling next year for the 50th

Steve, FV80