Aerodynamic Efficiency of F1 Cars

[Tommy Cookers]

An F1 car could drive upside down along the top of the tunnel in the Monaco GP, as long as it maintained a certain speed. If the tunnel was sloping down at a suitable angle, this speed could be maintained even if coasting in neutral.
The angle of slope required would show the efficiency of the aerodynamics.

In this ground effect situation any aeroplane made in the last 70 years could glide (at its best speed) through the tunnel at a 1 degree slope.

What angle of slope would the F1 car need ? (sincere question)

Would this sort of test help in the Greening of F1 ?

[Lycoming]

you realize nobobdy has actually driven an F1 car upside down in a tunnel before (though it is theoretically possible) and there are much better ways of demonstrating lift to drag ratio right?

[bhall]

I'm sure someone will chime in with the appropriate numbers, but I've always heard/read the line that even just lifting off the throttle in an F1 car slows it down as if one was braking heavily in a road car and taken that as anecdotal evidence that drag on an F1 car is pretty damn high.

[WhiteBlue]

According to Charlie Whiting F1 cars exceed 2.5 tons of downforce. The aerodynamic braking effect is approximately 1g which compares to 640 kg. So you would never be able to glide the thing. Considering that the car only weights 640 kg with driver you cannot reach a glide angle even with 100% negative incline.

Regarding greener designs the federation wanted the cars to go to 1.25 tons of downforce if possible with equal performance but the technical working group which was set set up to propose a low drag chassis with tunnels was over ruled by the FOTA internal voting. So we will probably see the stepped floor design and similar wings for some more years. Personally I would like to see F1 migrate to a lower drag, higher efficiency configuration. It would tie in nicely with fuel saving direct injection turbo engines.

[Just_a_fan]

A decent F1 car will have a L/D of 3:1 or better. I understand that they generally generate the equivalent to their weight at 100mph (so 640kg d/f at 100mph). So at that speed one would expect a drag of about 200-220kg.

The "braking at equivalent of a road car when lifting off the throttle" issue is, I believe, at top speed i.e. 180mph+.

The reason the cars are so draggy is because they are open wheelers with big rear wings that act as parachutes (the rear wing has a fairly poor L/D compared to the car as a whole) when they come off the power.

[Tommy Cookers]

Many thanks

[P.S.]

The reason the cars are so draggy is because they are open wheelers with big rear wings that act as parachutes (the rear wing has a fairly poor L/D compared to the car as a whole) when they come off the power.

I like to add, that also closed wheeler like lmp1 don´t exceed an L/D of 5. Even an Airliner has about 12-15. Modern gliders are between 40 and 70 depending to class.

So, open wheeler or not, cars are in a different league than aeroplanes.
But L/D ratio is a key factor in saving fuel, while going still fast around corners. So rules need to be changend (more freedom) when fuel efficiency is desired.

[Lycoming]

Cars are forced to use low aspect ratio wings because span is very limited, but a high lift coefficient is required. Although you can try and mitigate the effects by doing fancy things with the endplates, the fact is these wings generate a lot of induced drag. LMP cars do have much higher aspect ratios than F1 cars, and also generate more downforce from the undertray.

Also, a large part of the reason F1 cars are so draggy is because of the open wheels. There's a lot of turbulence around them, and they also represent a large percentage of the frontal area of the car.

[bhall]

If dirty air is so bad for overtaking, how was Vettel able to stay right on Alguersuari's gearbox through those corners?

[youtube]http://www.youtube.com/watch?v=69qj1MeSlSE[/youtube]

[Kiril Varbanov]

If dirty air is so bad for overtaking, how was Vettel able to stay right on Alguersuari's gearbox through those corners?

[youtube]http://www.youtube.com/watch?v=69qj1MeSlSE[/youtube]

He was slip-streaming.

[myurr]

If dirty air is so bad for overtaking, how was Vettel able to stay right on Alguersuari's gearbox through those corners?

Because he was doing something that we've seen Hamilton do a lot when trying to overtake - when following another car you take a slightly tighter line through the corner which positions your car into clean air restoring downforce. In the slower stuff you're more reliant on mechanical grip anyway.

Vettel wouldn't have been able to sit on Alguersuari's gear box through turn 8 in Turkey for example, as you can't really hold a tighter line through there and it's a fast aerodynamically limited corner.

[MadMatt]

Also the RB is way more efficient than the TR so that is giving Vettel an advantage too I think.

[strad]

Wouldn't Aerodynamic Efficiency imply something that slips thru the air? An F1 car with drag the equivalent of at least 1G is not very efficient. I think efficiency would imply little drag. Wouldn't it? A bullet has fair aerodynamic efficiency not an F1 car.

[Steven]

Typically, adding downforce to the car must be balanced against the consideration of increased drag, but at Monaco - where overtaking is almost impossible - we are prepared to accept lower levels of efficiency. Where for an F1 car, a typical lift/drag ratio is in excess of 3 (essentially, to accept a 1 percent penalty in drag, you must find 3 percent or more downforce), for Monaco it is possible to drop below this magic ratio.

[strad]

I guess it depends on what you call efficiency...to me a lot of drag isn't very efficient