Weight and aero load distribution

[Xwang]

Hi to all.
I would like to know if, generally speaking, is correct to say that weight and aero load distribution between front and rear axis should match and in such a case if also the width of wheels is somewhat correlated to those distributions.
Moreover I would like to know if is it possible to estimate where the center of pressure of a F1 like underbody lies.
Thank you,
Xwang

[VARIANT | one]

I remember an F1 engineer (I can't remember which one) saying you don't want them exactly coincident as you end up with a stabilizing effect and aero-biased understeer with the CoP a bit behind the CoG. It's something around ~ 2-3%.



And yes, tires are generally proportional F:R to manage those loads, mainly as tires go, to generate even wear and performance front-to-rear. Pit strategy plays into this though.

[Xwang]

So what if rules will gradually reduce the maximum weight on the front so that to force designers to use less front downforce on their cars and have cars with less problems to follow and overtake another one?

[JMS11]

So what if rules will gradually reduce the maximum weight on the front so that to force designers to use less front downforce on their cars and have cars with less problems to follow and overtake another one?

More downforce with a worse balance is usually still faster than having less downforce with better front / rear distribution. Because even if the car is aerodynamically unbalanced, they can still somewhat fix the balance other ways like spring / roll stifffness distribution or tire pressure.

So basically, the designers won't sacrifice front downforce just because you force them to take weight distribution off the front axle. The only way you can make them do it is to directly force them to have smaller / less effective front wings.

[JMS11]

So what if rules will gradually reduce the maximum weight on the front so that to force designers to use less front downforce on their cars and have cars with less problems to follow and overtake another one?

More downforce with a worse balance is usually still faster than having less downforce with better front / rear distribution. Because even if the car is aerodynamically unbalanced, they can still somewhat fix the balance other ways like spring / roll stifffness distribution or tire pressure.

So basically, the designers won't sacrifice front downforce just because you force them to take weight distribution off the front axle. If you want the cars to have less front downforce, the best way is to directly force them to make smaller / less effective front wings. Trying to indirectly make them design the car that way by changing weight distribution limits is only going to be 10% as effective

[Xwang]

So what if rules will gradually reduce the maximum weight on the front so that to force designers to use less front downforce on their cars and have cars with less problems to follow and overtake another one?

More downforce with a worse balance is usually still faster than having less downforce with better front / rear distribution. Because even if the car is aerodynamically unbalanced, they can still somewhat fix the balance other ways like spring / roll stifffness distribution or tire pressure.

So basically, the designers won't sacrifice front downforce just because you force them to take weight distribution off the front axle. If you want the cars to have less front downforce, the best way is to directly force them to make smaller / less effective front wings. Trying to indirectly make them design the car that way by changing weight distribution limits is only going to be 10% as effective

OK but only reducing the front downforce (smaller front wing) will create an unbalanced understeering car if at the same time the actual weight distribution is in use.
I didn't know that a not balanced with higher downforce is better than a balanced one with less downforce and I thought that the weight balance is easier to enforce that a reduction of front downforce.

[Greg Locock]

I think I'd need to see the numbers on that. The problem is that your mechanical balance applies at all speeds, whereas your aero balance mostly affects high speeds, so using mechanical balance to retune the car to make up for a deficit in front aero (say) will unbalance the car at lower speeds. This may be used to advantage, for example drivers may prefer a more neutral car at low speeds and a more understeer car at high speeds.

Now, to some extent you could get round the change of balance with downforce by using non linear ride springs or spring aids, but that then upsets your damper calibration. What you really need then are position sensitive shocks like the off roaders use, which have damping rates that vary in different parts of the stroke, or of course Magneride or equivalent production car technology.

[godlameroso]

F1 cars have to worry about aero balance at as little as 80kph, only about 3 corners besides the Lowes hairpin is slower than that. With such a long wheel base for most cars, low speed balance is essentially an afterthought.

[Greg Locock]

Low speed balance vs high speed is not a binary state, if the balance is poor at low speed and good at high speed it'll be mediocre at medium speed.

[godlameroso]

What does good medium speed balance get you? Ideally that's what you'd set your car up for seeing as the majority of turns in F1 are medium speed, and are also the turns where you can gain the most relative to others.

[Testdrive]

Interesting to look at this. I've been experimenting with F1 car's in a simulator, looking for that perfect COG and Aero Balance.

It's seems like for 1985 to like 1992, because of the tyre widths.
25cm and 37cmm rear..if you add them you get 62..then * it by 40% you get 24.8CM
So it seems for this era's optimal is 40% COG and 37% Aero Balance

For 1993 and up.
It's like 43% COG and 40% Aero Balance.

But still, 37% and like 34% Aero Balance is still derivable for both tyres. But there isn't as much frontal tyre grip.

Looking at the qualifying sessions in 1990's, it seems like their using 37% COG and 34% Aero balance. But it's hard to tell sometimes, wish the data existed some where.

[scarbs]

I remember an F1 engineer (I can't remember which one) saying you don't want them exactly coincident as you end up with a stabilizing effect and aero-biased understeer with the CoP a bit behind the CoG. It's something around ~ 2-3%.

http://jonsibal.com/bpimages/redbullX1_9.jpg

And yes, tires are generally proportional F:R to manage those loads, mainly as tires go, to generate even wear and performance front-to-rear. Pit strategy plays into this though.

Yes, that sounds like a Willem Toet quote.