Mid Corner Throttle?

[TeeLew]

I think we need to define "on the gas". Correct me if I'm wrong, but don't all of us go from brake directly to throttle after turn in?

No & this is a very important point.

In lower speed corners (2nd & 3rd gear), there should be a period of time where one has both feet up and allows the car to roll. This is the only way to fill the extremes of the traction circle. The cornering drag will still be slowing the car, so you're at max lat accel & some small amount of negative long accel.

It will take a certain amount (~3-5%) of throttle to reach max lat + zero long accel. At that point, the drive load on the rear tires equals the drag load of the front tires. Any amount of throttle beyond that will produce forward acceleration. One can really only initiate throttle application at or after peak steering angle. Adding throttle and steering angle simultaneously will induce understeer and delay the point at which you reach full throttle. It takes a ton of patience and discipline, but it is ultimately the fastest way to achieve full throttle, which, if we take TeeLewism #1 as valid, is vital.

It's counterintuitive, but the correct approach at some moments in the corner is to do nothing.

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[TeeLew]

I'm a bit indisposed presently, but give me a couple days & I'll put together some graphics to show the above approach in practice.

 

[Shadow277]

I think we need to define "on the gas". Correct me if I'm wrong, but don't all of us go from brake directly to throttle after turn in? Maintenance throttle of varying degrees until we start to track out and roll into full throttle as we approach end of pavement? I can't think of any other approach unless we're on dirt.
The grey area is how much maintenance throttle you use. I haven't seen anyone state they're at 75 percent throttle at the apex. If they are, then we can assume they are slow or driving an AH Sprite or double apexing 2 at Laguna.

Unless you're left-foot braking there's always going to be a brief period of time when your right foot isn't on either pedal. Even if you register your right foot by its heel on the floor between the gas and brake pedals and aren't involving lifting-the-whole-leg movements to go from one pedal to the other. Plus there's two little scraps of time when you're going from 'small' braking to none at all and during the early stages of ramping up on the throttle when the forward/rearward force demands on tire grip are low.

Side note to the Driver61 link's mention of heel-on-the-floor . . . judging by his picture I've been locating my right foot in that manner since before he was born - it just seems that natural. Though admittedly doing so can get in the way of heel-toe.


Norm

With that
being said, slightly different topic... Randy Pobst said slight throttle on turn in entry could be required to stabilize the car. Why? In what situation is that a viable technique?

 

[Shadow277]

I'm a bit indisposed presently, but give me a couple days & I'll put together some graphics to show the above approach in practice.

Hell yeah. Let me know. I'd love to see it. I'll do my best to use that technique on my next track day.

 

[TeeLew]

With that
being said, slightly different topic... Randy Pobst said slight throttle on turn in entry could be required to stabilize the car. Why? In what situation is that a viable technique?

If the car has entry oversteer, the driver will underachieve the entry to some extent & then have to go back to throttle to get load on the rear to avoid spinning. It's a technique to induce understeer which creates a boat load of problems, but sometimes that's the only thing keeping him out of the fence.

In this scenario, most drivers will report mid-corner understeer and snap loose at exit. The entry oversteer will rarely be mentioned. He'll have turned in early & shallow, because a late, aggressive steering input will induce a spin. He adds maintenance throttle, like Randy said, to stabilize the rear. At the apex, he's only done maybe 30% of the turning, so he has a slow minimum corner speed & ends up adding wheel to accommodate an ever shrinking corner radius. The throttle is applied, so load is shifted aft & the differential is locked, making the understeer terminal. As he gets to the exit, he's still not full throttle, but he's quickly running out of road and patience. So he gives it the boot which sidesteps the rear and causes a mad unwinding of the steering & cheers from thousands of adoring fans.

Entry oversteer is not a common complaint of nose heavy cars like ours, but it is very common in others. In general, we need to carry our braking into the corner to keep load forward & give the front enough authority to work. Genuine understeer gets a bad rap. It might be a little frustrating at times, but it's a damn site better than the alternative.

 

[TeeLew]

Hell yeah. Let me know. I'd love to see it. I'll do my best to use that technique on my next track day.

What tracks do you normally run?

 

[Hack]

Unless you're left-foot braking there's always going to be a brief period of time when your right foot isn't on either pedal. Even if you register your right foot by its heel on the floor between the gas and brake pedals and aren't involving lifting-the-whole-leg movements to go from one pedal to the other. Plus there's two little scraps of time when you're going from 'small' braking to none at all and during the early stages of ramping up on the throttle when the forward/rearward force demands on tire grip are low.

Side note to the Driver61 link's mention of heel-on-the-floor . . . judging by his picture I've been locating my right foot in that manner since before he was born - it just seems that natural. Though admittedly doing so can get in the way of heel-toe.


Norm

Yes of course I agree but I think of what you are saying here as semantics. If you are driving in a corner for anything more than a split second without touching either the brake or gas at all, you did something wrong.

No & this is a very important point.

In lower speed corners (2nd & 3rd gear), there should be a period of time where one has both feet up and allows the car to roll. This is the only way to fill the extremes of the traction circle. The cornering drag will still be slowing the car, so you're at max lat accel & some small amount of negative long accel.

It will take a certain amount (~3-5%) of throttle to reach max lat + zero long accel. At that point, the drive load on the rear tires equals the drag load of the front tires. Any amount of throttle beyond that will produce forward acceleration. One can really only initiate throttle application at or after peak steering angle. Adding throttle and steering angle simultaneously will induce understeer and delay the point at which you reach full throttle. It takes a ton of patience and discipline, but it is ultimately the fastest way to achieve full throttle, which, if we take TeeLewism #1 as valid, is vital.

It's counterintuitive, but the correct approach at some moments in the corner is to do nothing.

AFAIK that time when you are not touching either the brake or the throttle means that you did something wrong on corner entry (came in too fast or got off the brakes too soon). If you aren't using either the brake or the gas even slightly, I believe that means you aren't using the entire traction circle.

One thing I haven't done on track yet as a novice driver is to learn how much trail braking I can do. I know I'm leaving time on the table, but braking while turning is one of those scary things for me. I definitely haven't ever pushed the limit of traction with trail braking.

 

[Brian@BMVK]

Yes of course I agree but I think of what you are saying here as semantics. If you are driving in a corner for anything more than a split second without touching either the brake or gas at all, you did something wrong.



AFAIK that time when you are not touching either the brake or the throttle means that you did something wrong on corner entry (came in too fast or got off the brakes too soon). If you aren't using either the brake or the gas even slightly, I believe that means you aren't using the entire traction circle.

One thing I haven't done on track yet as a novice driver is to learn how much trail braking I can do. I know I'm leaving time on the table, but braking while turning is one of those scary things for me. I definitely haven't ever pushed the limit of traction with trail braking.

Not true for every corner. Most corners, yes. On street tires especially (even 200tw sticky ones), you also sometimes need a brief period to let the tire compose itself before going from some decel + turning to some accel + turning.

 

[Norm Peterson]

Yes of course I agree but I think of what you are saying here as semantics. If you are driving in a corner for anything more than a split second without touching either the brake or gas at all, you did something wrong.

Split seconds matter, and they do add up. I'm afraid that I don't have any way of accurately measuring how long it takes me to get completely off the brake to just very gently touching the gas pedal. But it seems to me that a quarter of a second sounds a bit too hurried to be smooth about getting into the gas.

AFAIK that time when you are not touching either the brake or the throttle means that you did something wrong on corner entry (came in too fast or got off the brakes too soon). If you aren't using either the brake or the gas even slightly, I believe that means you aren't using the entire traction circle.

Incorrect. Not that many people can perfectly follow the friction circle to begin with.

The entire traction circle includes the point where all of the traction is being used laterally. Where you can't add any braking or accelerating forces without exceeding the grip limit. There's a range around that where the amount of usable longitudinal traction is negligible - basically maintenance throttle. The distance involved depends on the particular corner.

Brake or gas plus cornering is for the in-between portions of the circle where neither full use of longitudinal grip nor full use of lateral grip is being used.


Norm

 

[Hack]

Split seconds matter, and they do add up. I'm afraid that I don't have any way of accurately measuring how long it takes me to get completely off the brake to just very gently touching the gas pedal. But it seems to me that a quarter of a second sounds a bit too hurried to be smooth about getting into the gas.



Incorrect. Not that many people can perfectly follow the friction circle to begin with.

The entire traction circle includes the point where all of the traction is being used laterally. Where you can't add any braking or accelerating forces without exceeding the grip limit. There's a range around that where the amount of usable longitudinal traction is negligible - basically maintenance throttle. The distance involved depends on the particular corner.

Brake or gas plus cornering is for the in-between portions of the circle where neither full use of longitudinal grip nor full use of lateral grip is being used.


Norm

If you are in a corner without touching the brake or gas, the car is slowing down rather rapidly. So you might use the limits of the car's cornering grip for a very short time (like the amount of time it takes to transition from braking to on the gas), but after that the car is traveling too slowly for the corner and you will no longer be at or near the limits of the car's grip.

I think you are trying to disagree with what I said by stating that maintenance throttle doesn't count as touching the gas pedal. Maybe I'm misunderstanding, but if that's what you're trying to say it's a really dumb argument. Semantics again.

 

[TeeLew]

Not true for every corner. Most corners, yes. On street tires especially (even 200tw sticky ones), you also sometimes need a brief period to let the tire compose itself before going from some decel + turning to some accel + turning.

Clearly, I believe it's more than the just the occasional corner, but allowing the tire to stabilize is an important point as well.

 

[Norm Peterson]

So you might use the limits of the car's cornering grip for a very short time (like the amount of time it takes to transition from braking to on the gas)

IOW, what I already mentioned. Handling is a dynamic process, and the time element matters.

I think you are trying to disagree with what I said by stating that maintenance throttle doesn't count as touching the gas pedal. Maybe I'm misunderstanding, but if that's what you're trying to say it's a really dumb argument. Semantics again.

"On the gas" has always meant acceleration to me. Significant acceleration. Not simply touching the gas pedal.

Staying on the friction circle means that you have to manage the lateral and longitudinal forces in accordance with the mathematical equation for a circle.


Norm

 

[TeeLew]

"On the gas" has always meant acceleration to me. Significant acceleration. Not simply touching the gas pedal.

Any amount of throttle application will induce load transfer from the front to the rear and alter the friction characteristics of the differential. Once initiated, it's a matter of degree, not kind.

 

[Norm Peterson]

Any amount of throttle application will induce load transfer from the front to the rear and alter the friction characteristics of the differential. Once initiated, it's a matter of degree, not kind.

Exactly.

Just not sufficiently descriptive, else there never would have been reason for terms like trailing, leading, neutral, or maintenance.


For a few of us, the phrase "on the gas" will be forever linked to Danny Ongais.


Norm

 

[TeeLew]

No 'the'. Danny 'On Gas' and, all too often, Danny 'In-Fence', lol!

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