Oversteer/Understeer

Sorry, don't mean to be a pest, but I keep thinking about this. (I know, I know, I think too much.) So basically the difference between aero v mechanical grip is you stay on the gas more with aero, yes? But does aero give you that much more grip?

I did my race school with Skippy at Laguna and blowing into T2 called for doing the 11/10ths to 10/11s boggie as you did the arc around the turn, i.e. trail braking understeer transitioning to throttle braking oversteer with the tires doing the Deliverance squeal the whole way. It is just hard for me to imagine that my tires had any traction budget left, aero or no aero. Am I understanding this wrong?

Dale

 

At speed, aero gives you far more grip. Think about an F1 car that generates more than 1x the car's weight at speed. That means, it can, theoretically, drive upside down. Take the speed away and...

The Skippy cars were a perfect example of mechanical grip cars (now they have wings, right?). So, the grip was based entirely just on gravity, suspension and lateral loading. Add some aero, and go faster, and by generating more downforce, presto! Definitely faster.

CW

 

It's an exercise in getting faith!

CW

 

You're right, it is counter intuitive. I'd like to think that my traction budget was at zero in the Skippy cars. But I guess if you're pushing down that hard you get the tires to make you a loan. But I'm also guessing this must be hell on tires. Do you have to run harder compounds on the aero cars?

Dale

 

You can, and it would depend on the life you want out of your tires. If you're looking for pure speed (say, in quali), you could go with a softer compound, but they'd be shot relatively quickly. Same deal as F1. Everything's a tradeoff. Also, track conditions such as heat and surface material play a role in tire wear rates.

We typically run a middle or harder compound, as the focus is on getting through a 3- or 4-day weekend on two sets of stickered tires. The primary set will have over 100 laps on them by the end of the weekend (although, strangely, I've put in some of my fastest lap times of a weekend on 100+ lapped tires). As it turns out, my driving style is not hard on tires, and they still look great at that point (although they're heat cycled at that point so many times that they're pretty much done).

CW

 

Is this because you don't brake as much, as in brake late and release early?

Dale

 

Vision is an under-appreciated skill for drivers. I had a discussion recently with a very good driver who said the exact same thing. The more you can take in and process, visually, the better. I shoot sporting clays competitively when I'm not driving in part to keep my eyes working, and I think it's helped when I'm in the car.

Wet driving's interesting. It's not anyone's favorite, but it is definitely an opportunity to take advantage of. It can level a playing field instantly. I can't say I have enough experience in the wet, but I'm always eager to improve my skills!

CW

 

I've always been told, "smooth is fast".

And, as I've gotten better at telegraphing what was coming so the car isn't stressed any more than necessary, my lap times came down. This involves pre-loading for corners, for example, and smooth (and slow) turn-ins, with only throttle steering through the corners (as opposed to steering input...in other words, turn the wheel once, and hold it where it needs to be to let the tires do their job without breaking any traction).

Smooth application of (both on and off) the brakes. Even earlier and lighter application of the brakes (as opposed to threshold braking and trying to ring the car's neck). I remember seeing data analysis from F1 many years ago and the secret to Schumacher's success at the time (during his Ferrari dominance) was earlier braking and carrying more speed through the corner. So, my focus is less on late-braking than it is on higher entry, mid-corner and exit speeds. I am generally even using lower and lower rpm limits throughout the weekend just to preserve engine life, but going faster and faster. This just re-confirms that there's more time to find in the corners than elsewhere.

BTW, all of this is manifested in every component of the car. Being sympathetic shows up in the motor, gearbox, brake rotors, suspension, tires, etc. I know drivers who are very hard on their cars. Violent, even. Maybe it works for them, though.

CW

 

Dammit, I told myself that I wasn't going to post on Ferrari Chat today because I need to get some work done. But this smoothness thing drives me crazy. (I think I once started a thread on this topic.) I can drive smooth. I can drive 10/10s, but I can't drive smooth and 10/10s, or at least it doesn't feel smooth to me. In fact, going 10/10s feels like I'm about to take a swan dive into the brier patch.

Maybe I don't have enough seat time on good tires to develop a feel for the physics of my tires. In this sense, racing might be like golf. In golf, the whole game is that split second when the club hits the ball and understanding the physics of a flat surface with ridges hitting a ball with dimples. Going 10/10s is about feeling just the right slip angle for a given set of tires on a given course. Maybe my problem is I'm trying too hard (which is also a problem in golf). In trying to go 10/10s, I'm sawing back and forth between 11/10s and 10/11s. Damn, I gotta get back to the track, Jack.

Dale

 

Sorry, the internet saps ALL the productivity!

Not to wax philosophic, but it's an ideal that's sometimes attainable.

When I'm "there", for me, everything slows down. You just have it figured out. It's not conscious. You're not thinking about braking zone, turn-in point or which gear to be in. You're just doing it. Don't get me wrong, there's LOTS going on. If you've got in-car video, you can see it all happening.

Like anything, the more you do of it, the better you'll become.

CW

 

Thanks, you give me hope. Now, I gonna turn off this ******* Internet and get to work!

Dale

 

The question I have for you aero guys is can you comment on the "deadzone" which I assume there is. If you have a tintop car like a corvette with splitter and wing you can't generate much meaningful downforce at our sub 160mph clubrace speeds. In fact lot of time is under 120 where good rear wings make a whooping 3-400lbs of downforce on 3000lb car at best. So for us there is no push through where if we don't drive the corner fast enough we loose the downforce and fly off the track.
Some have commented on the need to keep your foot into an aerocar to make it work. An F1 car in theory can drive upsidedown. I would guess that there is a zone from xmph to ymph a deadzone where you don't want to be in an aerocar or need to keep as short as possible as you transition through it.
So the question is how do you find the deadzone? Do you calculate it then test it? I guess the deadzone might be defined as the gap between the point of greatest mechanical grip and the real aero benefit whoever that is defined. I think I'm rambling...

 

There is a "deadzone", as you put it. If you can't "push through", you'll just get more push (sorry for the way that's worded). The other option is to take rear wing out and adjust the downforce to better balance it between front and rear. Each car will be different (and that "deadzone" can be narrower or wider), based upon all the factors, but I'm not an aerodynamicist. However, I'd wager it's largely formulaic. As, much of design is based on dynamic flow analysis, and cars are designed on computers (CAD, CAE, etc.) today, I'd venture that it's not that difficult to calculate based on drag coefficients, estimated downforce and so forth. We could ask lmpdesigner. He'd know.

CW

 

CornersWell, thanks for the enlightening posts. What type of cars do you drive?

 

Glad if they're helpful.

These days, mainly just GT.

CW

 

I got my first true taste of Aero this week. It is truly an amazing thing.

Carrying almost 200kph through turn 4 at Mosport was something I did not think was possible.

The push through the aero deadband is not as bad as many make it seem. I am sure this depends on your car and setup though.

Once you go Aero you never go back!

Ron

 

We need pictures!

 

This is an awesome question! As a coach of 30+ years this thing you speak of may be the most difficult thing to teach a driver who is learning to use aero for the first time.

I have done it with some success as my most famous client transitioned from GT to Prototypes and became better as a "down force" driver than he was as a mechanical grip driver. He did it on road courses, which is what I will address here. Doing it on an oval at Indy for example is a more complicated process and less relevant for us sporty car types.

Its this "deadzone" you mentioned that is the critical issue. A perfect car would make the transition from mechanical grip to aero grip completely seamlessly with no change in the drivers perception of balance. It would be easy to drive because the driver would sense the downforce simply as more grip in the same way he might feel bigger or softer tires. Unfortunately, this goal is complicated by flat bottom rules, tire limitations or even spotty engineering. So as the driver how do you get past this "barrier" without bending a lot of parts?

The obvious plan would be to grit your teeth and charge the corner with Chuck Yeager-like courage and hope you come out the other side alive. Many drivers take this approach, but they wind up chickening out just before the corner, lifting or braking and losing all the down force at once. If they make it, they have lost confidence and are too scared to try it again. They have set themselves back from learning to drive the downforce.

But there is a safe and simple approach where you can build confidence and begin to get a "taste" for the downforce and learn to trust it.

First, we need to understand that the downforce is created by using some of the horsepower of the drive wheels to "push" the car harder into the track using whatever devices are in play. Tunnels, wings, dive planes etc. This is important to understand because if you lift off the throttle before the turn, you trade thrust for drag and several things immediately reduce your down force and grip. First, the car "pop's" up a few thousands on an inch off the track and reduces any underwing or tunnel effect. Second, the balance of grip front to rear may change in a negative way. Third, your braking force is reduced. This last thing is important because you have just reduced your ability to corner by many MPH and you will NEED to slow down. This is your frightening "deadzone".

I know you are thinking, but what if I NEED to slow down, you know, to make the corner?

No sweat. Use your left foot to slow the car early while keeping your right foot hard on the gas. This will keep the platform stable, the down force solid and consistent and allow you to work up to an entry speed that may not require more than a brush of the brake or nothing at all...and as you are working up to it you will never feel the "deadzone".

Why does this work? The explanation is simple. With a stable platform (gas on) the car will make more down force at a lower corner entry speed, than it will with the power off at a higher entry speed. The difference between the two is FBB's "deadzone". If you use my method, you can completely avoid the "deadzone" and safely learn to explore the limits of a down force car without scaring the hell out of yourself!

PS. I am a confirmed right foot braker, willing to take on all you confirmed left foot brakers anytime. But for this purpose, for driving a downforce car, you must use the left foot if you want to survive the "deadzone"!!!

 

Ed,

Thanks for the explanation. What you post makes perfect sense. Nice to know that there is a progressive way to live with aero.

I find the LFB helps me with a mechanical grip car too. I'm not sure why. Maybe it is the stability of platform thing. However, I have a mental problem for some reason I can't overcome. I LFB perfectly in automatic or Ferrari F1 paddle shift type cars. I have never drivin a sequential crashbox. But I cannot LFB with manual gearboxes. I'm not sure why my own shortcoming. Heel/toe is no problem at all like second nature but I have real trouble with heel/toe to LFB transition. I don't know why. The only thing that sort of works is to brake early and shift, LFB and try to be on the gas earlier. But I have this balky transition from RFB/heel/toe to LFB where I unpredictably upset the car. Maybe I just have a complete lack of coordination or maybe that is why a paddle shift car is generally faster and is generally penalized in GCR's vs. the manual variant of the same car.

 

A good verbalization. I've moved to LFB as I spent more time in paddle shifted cars, but it's also made it much easier and more natural to use braking as an element of the turning process. I do more turn-ins under trail-braking, and I'm almost always braking earlier (but lighter), focusing on entry and exit speed.

Again, the smoothness factor (during transitions) plays a role in all this as unsettling the car also upsets the aero.

CW

 

One thing I've found is that the pedal size in a paddle shift is over-sized, because of the lack of the third pedal. Thus, even finding it is easier. And, you just don't have to think or worry about that 3rd pedal out there on the left.

In contrast to the 3-pedal set-up, in which I have to search around for the brake pedal on occasion (coming over from the dead pedal) to pre-position it, and if a lot's going on in a very short amount of time...

I don't think what you're explaining is something peculiar to you. I'd say, just spend more time in the manual, 3-pedal car, but what gets my muscle memory confused is the going back and forth between them.

CW