12 replies to this topic

[biercemountain]

While daydreaming about the possible consequences of adding enveloping bodywork to a modern Formula 1 car I realized some of the answers might be available already. It suddenly struck me that comparing F5000 cars to the Can-Am cars they morphed into might provide some clues.

How did these cars compare in performance in open wheel configuration as opposed to closed body form? Was there any kind of appreciable aero benefits? Was there a weight penalty due to the additional body work? How did straightline speed change? What about cornering?

It seems like it would be a pretty "apples to apples" comparison considering that the basic chassis and engine remained the same (I would assume). As I don't have enough data in my own library I was wondering if anyone had any information along these lines.

It also raises the question, what would a modern F1 car be like with enveloping bodywork?

[tedmna]

Many say the current Audi LeMans prototypes are very much like a F1 car with bodywork.

[hchen]

you mean the GT1 class vehicles... i'd agree those are the closest closed-wheel vehicle to F1-

streetcar-wise, the ferrari enzo and mercedes slr...

[alexbiker]

This from the recent Race Tech:

Current prototypes [meaning GT1 racers] can generate more downforce at a given speed than a formula one car. Of course, an F1 car has much less weight and much more power, and is therefore faster, but the fact remains that every prototype should be aerodynamically more efficient than any open-wheel racing car.

Andy Thorby, designer of the Lister Storm LMP

So, were the engines derestricted, we'd see LMP's like the Bentley faster than F1 cars. The weight (900kg) could be overcome with a nice 1500bhp engine. Basically, you can't do much aerodynamically about a tyre - they really do have to be round, so if they're in the airflow, boy are they going to cost you. Although the rears on modern F1 cars are practically covered, the fronts are still huge in the airflow, and will remain to be with current front wing restrictions.

Alex

[gug]

one of the problems with open-wheelers is that a rotating cylinder moving through a flow (such as a tire through air) causes either lift or downforce. in the case of cars, its lift. i suspect you have seen it before, but there was a 6-wheeled car in F1 a long time ago, designed to reduce the drag off the front wheels.

i would imagine that the benefits of closed wheels would be greater than the added weight in any car that goes over 100kph, especially when materials such as carbon-fibre are used.

[alexbiker]

The major effect of wheels is drag, especially considering the air incident on the tops of the tires is effectively striking a surface travelling at twice the speed of the car, and since drag roughly equals speed squared, that's four times the drag of the rest of the bodywork, and over a large suface area.

Alex

[Greg Locock]

The ever reliable Milliken says that the Cd of a rotating tyre is 0.579 for a standard rim, and has a lift coefficient of 0.18, both on a frontal area basis.

[JacnGille]

If I wasn't about to go out of town I'd drag out my old Road Atlanta race programs and look at the F5000/Can Am track records. Sorry.

[wibblywobbly]

I would think that the increased frontal area of "sportscar" bodywork would slow the car, considerably from its F5000 state, as well as creating much more downforce.

[Paolo]

A full bodied F1 would run rings round the open bodied ones.
A F1 car Cd is between 0.8 and 1, based on frontal area.
A prototype will hardly be over 0.4-0.5 even in high downforce configuration.
Even a 20% increase in frontal area (to be expected with a full body) won't offset the advantage.
There is no reason why a full body could not produce the same downforce as a F1, although full bodies usually have problems in generating downforce at the front end.
This could be offset with a more rear biased weight distribution , wich would by the way improve traction .
There is an area in wich the full body would lose, anyway : the driving is less precise, especially near the curve's apex.
That's because the pilot cannot see the front wheels.
And it is one of the reasons why Fangio and Moss didn't like the full body option on their Mercedes.
Also, if the weight shifts back as suggested, the polar moment of inertia will increase.

[Yelnats]

While watching in-car camera views of ALMS cars running in the USA I was astonished to see the G-force meter banging offscale (3 G) at almost every turn except the hairpins. Most of these corners were in the 100 mph (160 kph) range. An examination of F1 track maps shows similar turns are taken at well below these G forces, more like 2.4 to 2.6 Gs. There is no doubt that the severe limitations on design placed on F1 cars would put them at a huge disadvantage to a streamliner version of the same car assuming maximal undertray down force .

But the question here asks only about the benifits of enclosed wheels, not improvements to down force generated from underchassis effects of an enclosed vehicle. We only need to look at history to get some idea of the results of such a design change.

About 50 years ago Mercedes ran two versions of the same car, a streamliner on the high speed tracks and an open wheeled car on the tighter courses. These were perfectly suited to their application as the heavier streamliner gave up too much acceleration to be competitive on shorter track where acceleration was a primary factor and top speed irrelevent.

This was in an era when cars ran no ballast so the streamliner must have been heavier, which wouldn't be the case today when F1 cars carry about 80 kgs of ballast which could be reduced with on an enclosed wheel design. Incidently Fangio complained about not seeing the wheels and had much less success driving sports cars of any type whereas Moss had no problems with enclosed wheels and happily drove anything he was given.

A low drag enclosed wheel F1 car today (with the same undertray design) would have the immense advantage of being able to run much larger wings to generate greater downforce per unit of drag which would be the determining factor in reduced lap times. The lower drag would not be used to generate significantly higher speeds which also applied to the 1,100 HP cars of the eighties which were no faster than the cars of today as the greater HP was converted to downforce instead of higher top speeds.

To answer your questions re a modern F1 car.

There would be no weigh increase as the ballast would be removed to accomodate the additonal weight of the bodywork.

Top speeds would not signigicantly increase as the reduced drag would allow designer to put bigger wings on the cars for greater downforce.

With greater downforce and the same or lesser drag, lap times are bound to fall significantly.

[Christiaan]

When the F50 was released Ferrari allowed several journalists to race it head to head with Alain Prost's car from which it was based. I saw a BBC car on it and the racing was unbelievably close. I don't know if you could find any more technical data on the race (The F1 car won by a couple of metres BTW) but I'm sure its out there.

[Yelnats]

Pardon me for my cynicisim but certainly a staged race with a staged finish. No way would Ferrari publicly thrash their new roadster.