Underbody Tunnels

[KevlarUSA]

Why doesn't the FIA re-introduce underbody tunnels to F1? I've seen many comments on GP2 on how close the can drive behind each other using them. From what I understand
most of the turbulence generated by an F1 car is made by the diffuser. Why not kill the diffuser entirely and ad tunnels?

[Ciro Pabón]

AFAIK, F1 cars have tunnels... that's why you need a diffuser, unless I'm completely mistaken.

[Ogami musashi]

No they don't.

The diffuser is there precisely because they don't have tunnels. Tunnels are airfoil like sections so it can be considered the downstream part of the tunnel be like a diffuser.


That's why with flat bottom cars the diffuser tries to act like a downstream part of a tunnel.

Tunnels are more efficient though because the speed variations are smoother and there's the upstream acting a bit like a reverse diffuser.


They're not re-introduced because a lot of downforce can be gained there, see actual diffusers that are supposed to have brung back the downforce levels to the same than last year.

The all Ground effect solutions is also not desirable for overtaking but it is clear that tunnels balanced with wings would be a good solution.

[blackwell68]

Sure bring back tunnels, why not?
Anything that can be applied to road cars is OK with me.
Just raise the ride height to reduce the huge gains in overall downforce.
We would like them to occasionally brake for turns.

[WhiteBlue]

Perhaps one has to distinguish between open and closed tunnels. The DDDs use closed tunnels to pick up air further forward and transport it to the upper diffusor section.



closed DDD tunnel

The open tunnels would be a departure from flat bottomed cars. I wonder what the stability would be over curbs. There is certainly ground effect involved that could collaps when cars slip laterally or jump over curbs. Wings would provide some more reliable down force. A combination as ogami musashi suggested would probably be desirable. Would the wake turbulences be better or worse compared to a diffusor solution?





open venturi tunnel

[PNSD]

At a guess id say better. again a guess but a diffuser to me seems to induce a much higher exit angle for the wake, its almost vertical!

As for bouncing over curbs, surley thats only an issue at high speed, in which case bouncing over curbs is never an issue because its always avoided. The flat bottoms prevent pitch-instability I always thought. To divert from that could be dangerous.

If people are really bothered about the wake then F1 needs to start looking at covering the wheels and tyres. But of course its not open-wheel racing.

[PNSD]

At a guess id say better. again a guess but a diffuser to me seems to induce a much higher exit angle for the wake, its almost vertical!

As for bouncing over curbs, surley thats only an issue at high speed, in which case bouncing over curbs is never an issue because its always avoided. The flat bottoms prevent pitch-instability I always thought. To divert from that could be dangerous.

If people are really bothered about the wake then F1 needs to start looking at covering the wheels and tyres. But of course its not open-wheel racing.

[BreezyRacer]

I would say the FIA got the passing rules right last year .. TILL they made double decker diffusers legal. In the first few races of the year there was a lot more passing going on and cars could run right up on top of each other. Now that we have the much stronger diffusers it's pretty much like last year even though we have moveable wings, a narrower aero profile with the lifted and narrowed rear wing, some KERS cars, etc. Just my opinion of course but I wish they hadn't legalized the double deck diffusers.

[Conceptual]

I would say the FIA got the passing rules right last year .. TILL they made double decker diffusers legal. In the first few races of the year there was a lot more passing going on and cars could run right up on top of each other. Now that we have the much stronger diffusers it's pretty much like last year even though we have moveable wings, a narrower aero profile with the lifted and narrowed rear wing, some KERS cars, etc. Just my opinion of course but I wish they hadn't legalized the double deck diffusers.

I can't believe people are still crying about the DDD.

Don't you have anything better to whine about?

[OrStateAero]

FACT: Present F1 cars do not utilize "tunnels" as the original poster is referring to.

FACT: Diffusers ARE NOT just utilized when tunnels are not in effect. It's all down to creating a more efficient underbody.

FACT: the DDD is acting like a rear tunnel. Increase in mass flow = increase in downforce.

Remember: The diffuser isn't THE CAUSE of the downforce, it is the improver of the downforce. The underbody naturally creates the downforce (following basic designs at least, like a flat floor).

[DaveKillens]

It's about a bit of history. Back when Colin Chapman pioneered ground effects, tunnels and sliding skirts suddenly became the norm. This alteration to the car was a performance improver, and suddenly the G's cars could generate in corners was amazing. Too amazing, because eventually drivers started to complain.

To be honest, there was no such thing as cornering technique in the ground effect era. “Cornering” was a euphemism for rape practised on the driver. . . When you came into a corner you had to hit the accelerator as hard as you possibly could, build up speed as quickly as possible and, when things became unstuck, bite the bullet and give it even more. In a ground effect car, reaching the limit was synonymous with spinning out.
— Niki Lauda —

They had become dangerous. So ground effects and sliding skirts became illegal. And in an effort to combat clever engineers, the bottom of the car was mandated to be flat. From now on, as far as the rules makers were concerned, downforce would come from the wings alone. But of course, clever engineers find a way around problems, and these rules concerning flat bottoms and venturis are constantly changing.

[RacingManiac]

my understanding is that the difficulty in recent years for passing was due to the fact that cars are heavily reliant on the wings for majority of the downforce, especially on the front end, where the sole-contributor of the front aero balance was the front wing. Wing don't work too well in wake condition, and once you've taken that downforce away the car suffers from understeer and loses ability to brake fully, hampering the ability to execute a passing manuver. And due to the fact of lacking a fully utilized underbody compare to a tunnel car, with disturbed front wing flow the device downstream don't work as well so you lose downforce altogther. With a tunnel car you should still be able to maintain your overall level of downforce, which should help a car following another car.

I think there are enough series around that shows that sensibly utilized floor tunnel should still encourage racing without running into the issue of f1's full ground effect time. Indy Car(Champ Car), Le Mans, Atlantic and others seems to be alright on that front. I don't think it'll be that bad for F1 to follow Le Mans to have a spec floor, and ride height limit, but lets them do other things they want. It certainly have not hampered LMP car from being different to each other in the areas they can be.

[ISLAMATRON]

Those cars still didnt corner with the same cornering G's as today's, the tires did not allow for it.

There are plenty of series that employ tunnels and are within the realms of common sense. IRL & GP2 to name a couple. Ground effects are not a safety hazard if employed with proper restrictions.

[BreezyRacer]

Tunnels are the last thing F1 needs to think about. They already generate a full third of their DF from the undertray. They really need to get the aero designs setup for passing again.

And next year the cars will likely to be pushers, due the narrower front tires. Maybe next year they should specifically outlaw the DD loophole to balance things out a bit. That way we'll get back to the smaller wake that the cars had at the beginning of the season. Passing could return.

[wesley123]

Those cars still didnt corner with the same cornering G's as today's, the tires did not allow for it.

There are plenty of series that employ tunnels and are within the realms of common sense. IRL & GP2 to name a couple. Ground effects are not a safety hazard if employed with proper restrictions.

But such things are pretty impossible with f1 teams going on the limts and over it(breaking the rules sounds dull :p) and the FIA setting up unclear rules.
But if they CAN manage to do it, it is a good idea, all racing series that use tunnels have good passing, so with current rear wing and front wing possitions it isnt a bad idea.

@BreezyRacer; bullshit, the DDD has 0 effect, the air is as clean as it is in the normal tunnel, it only goes throug a channel where it generates more downforce.
Also the downforce the underbody generates is good for overtaking, as its wake is less then from wings etc. so you should get more downforce from the underbody, The 2007 Panoz Champcar utilizes it and it was a good car for overtsking i believe.