Smoothness

[Skypalace]

Different drivers achieve simiar results with different styles. Some have a smoother style than others, but it doesn't mean the results are any better.

I use Schumacher and Alonso as examples. Schumacher's inputs are very smooth - going into a corner, he knows exactly how much steering angle to use, etc. and he has very little steering wheel movement in the corner. Alonso turns in later and sharper, and is constantly adjusting during the corner. He's sensing grip constantly and adjusting in real time, while Schumacher knows exactly how much grip is there (as he's on the same line as last lap, and knew the grip then). Vettel's style is much closer to Schumacher's than to Alonso's.

My style is much more like Alonso's. I'm not good enough to know in advance exactly how much grip there is and what the perfect steering angle is that'll take me through the corner at that grip level. When I'm pushing, whether in the dry or wet, I'm constantly sensing and adjusting, and it might not look very smooth (as I'm constantly adjusting the inputs), though it's definitely not upsetting the car, as the inputs themselves are not abrupt.

I showed in-car video of two laps of mine to some co-workers who had been doing DE's at the same track and had some questions about line (my line in one particular corner is very different from the 'school line', that I happen to think is a particularly dangerous line for that one corner. I hadn't particularly noticed, but they asked why I was so smooth in the first video, and so jerky in the second. (This was in reference to their instructors telling them to set their line in a corner and they should never have to adjust the steering wheel unless they had the wrong steering angle to start with).

Easy answer - first video was an early practice lap on cold tires, three or four seconds off the pace, easy to be smooth as I wasn't near the limits nor of course trying to be. The second video was a qualifying lap within a tenth of the track record. I was constantly on the edge and adjusting to keep it there, so even in a long constant-radius corner I was constantly moving my hands.

I also showed the Motec data - lateral g's were equally smooth, but of course higher in the faster lap. So another way of saying that smooth is the outputs of the car, not the inputs.

I strongly advice people to do as much rain track time as possible, it's a great learning experience for forcing smoothness, and learning how to sense grip. I recently had a fellow competitor (who I'd lapped twice in a rain race) ask how I was so fast in the wet. I asked him if he felt like he was hooked up through the whole lap (we were both on full rain tires). He said yes. I told him that I was loose under braking, on turnin, at apex, and tracking out, on every corner, of every single lap (I actually lied about the last part, as I backed off once I'd lapped the field). His jaw dropped, like that was the craziest thing he'd ever heard.

But if you're smooth on steering, braking, and accelaration inputs (which to me means a low standard deviation ie. low rate of change), and are able to sense when you're losing grip and then (smoothly of course) back slightly off, then you can play on the edge and learn tons and tons about car control, in a much more forgiving environment than in the dry (as the dropoff in tire grip between static and dynamic friction is MUCH higher in the dry than in the wet).

Jim

[csmarx]

Originally Posted by Skypalace

I strongly advice people to do as much rain track time as possible, it's a great learning experience for forcing smoothness, and learning how to sense grip. I recently had a fellow competitor (who I'd lapped twice in a rain race) ask how I was so fast in the wet. I asked him if he felt like he was hooked up through the whole lap (we were both on full rain tires). He said yes. I told him that I was loose under braking, on turnin, at apex, and tracking out, on every corner, of every single lap (I actually lied about the last part, as I backed off once I'd lapped the field). His jaw dropped, like that was the craziest thing he'd ever heard.

But if you're smooth on steering, braking, and accelaration inputs (which to me means a low standard deviation ie. low rate of change), and are able to sense when you're losing grip and then (smoothly of course) back slightly off, then you can play on the edge and learn tons and tons about car control, in a much more forgiving environment than in the dry (as the dropoff in tire grip between static and dynamic friction is MUCH higher in the dry than in the wet).

Jim

So true.

I learned so much from wet handling practice at a specially designed track in Belgium. One part of it is so slippery that if you even THINK about steering, you slide sideways. It exaggerates everything and really forces you to think ahead about what the car is going to do and how it's going to react to your input.

Even at the 5 day racing school I attended at Silverstone about half the seat time was spent sliding cars around in the wet and dry.

I sometimes wish it would rain more here in California!

In discussing smoothness with students, I like to point this out: learning to drive isn't so much about learning to drive at the limit - that's easy, just yank on the steering wheel - it's about driving in such a way that the car's limit is higher. In other words, students often wind up sliding their cars in a turn by doing it all wrong, and they are all elated because they "drove at the limit." Meanwhile a professional driver (which I'm not) could take the car around the same turn at twice the speed with no drama at all. It's a subtle point bordering on semantics, but I find that students who get the difference learn much faster.

Your comment on input vs. output also goes back to my earlier post in this thread about sinusoidal inputs. The point was that because of the physics of a car, in order to get linear (i.e. smooth) outputs, you have to give sinusoidal inputs. That's just the nature of a spring, mass, damper system, which a car is. I know it's a bit simplified, but I do think a lot of what we are talking about in terms of how to get on and off the brakes, the gas, etc, can be boiled down to a sinusoid: gently on at first instant, accelerating swiftly to hard on, then rolling gently off. A sinusoid!
(Sorry to harp on about this, I've just been thinking about it a lot lately...)

-Christian

[adias]

Originally Posted by Skypalace

Different drivers achieve simiar results with different styles. Some have a smoother style than others, but it doesn't mean the results are any better.

I use Schumacher and Alonso as examples. Schumacher's inputs are very smooth - going into a corner, he knows exactly how much steering angle to use, etc. and he has very little steering wheel movement in the corner. Alonso turns in later and sharper, and is constantly adjusting during the corner. He's sensing grip constantly and adjusting in real time, while Schumacher knows exactly how much grip is there (as he's on the same line as last lap, and knew the grip then). Vettel's style is much closer to Schumacher's than to Alonso's.

Alonso used to drive as you describe. I think he's much smoother now.