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- - Smoothness (http://gt2gt3cup.org/showthread.php?t=273)

In several threads we touched on being smooth while driving in any condition, and I have struggled to properly define what smoothness really means. Luckily I am not the only one.

Mark Dalen, who is part of Racer University and is an automotive engineer with many years of racing experience in various sports racers to include high-downforce cars, took the time to explain it. Here is an excerpt of it:

Quote:

What we really care about is not smooth inputs to the car, we care about smooth outputs. We care about the car being balanced. We care about doing things as quickly as possible, without upsetting the car and losing time on track.
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Why were we taught to use smooth inputs? That is simple. As a beginner, we were not sensitive enough to the balance of the car to pay attention to that. The only tool we could master, at that stage, was smooth inputs.

What are the lessons to take from this?
1. As your skills advance, focus on the balance of the car, not the smoothness of your inputs.
2.
3. (there are more, but cannot post it here directly)

For the details on the supporting data for his points, you can look for Course # 317.

Sounds familar!

"focus on the balance of the car, not the smoothness of your inputs"

This has been my focus recently but it's easier said than done when you're not comfortable with the car or the track. Ran two tracks this week and struggled with feel and confidence.

I know most recent memory seems to override others, but in your case it is the change of your car setup, you'll be back to the level of confidence you're used to in no time.

I guess part of the theory is feel the car in such a way that you work with it proactively, not in reaction. So, what ever the conditions may be, feel what the car can do, you adapt to it, rather than expecting the car to do so, it cannot.

YES!

Quote:

"focus on the balance of the car, not the smoothness of your inputs"

That is very well said! I will use that with my students. I always show them smooth, but then they say the inputs are very aggressive. I have to then explain the car is always in balance, etc. This is great!

How do you teach the difference?

Humm, with explanations like:
"Turn in like you close up a big vault door tight"
"firm, but not shocky"
"It's OK to drag your foot of the brake padel when going for the throttle, so I can't feel it"
I could use some help with clear terms for the student..

I have no doubt they'll get that story the first time :ROFL!:

I guess smooth means different things to different sets of drivers; subjective I suppose. What smooth / fast / slow / aggressive / etc. means to me is not what smooth means to a racecar driver. I don't think you can nail down just one definition of smooth Fatih.

I'm still at the 'smooth inputs = smooth outputs' stage.

When you put the car on the edge of its abilities, then is when I think you see the 'sawing' at the wheel (which contradicts what you are thinking smooth should be), when very fast but smooth and minute adjustments are being made to keep the car balanced and everything just right. JMS(low)O

Everyone has their theories and techniques... mine in regard to smoothness, is: smooth inputs = smoothness and ultimately speed on the track. Even while at the limit, smoothness in the cockpit is what makes for consistently fast laps.

Take a look at this video of Sebastian Vettle's pole lap in qualifying earlier today at Valencia Spain. I just finished watching this on TV, and this is the only version I could find on the Web. I'm sure others will pop up.

This is a lap record of 1:36.9xx, the only lap ever turned on this track in the 1:36s. You'll notice that except for two pretty big - and necessary corrections, and the few places where he's having to fight the wheel a little when he's up in the curbs - his inputs are smooth as silk.

http://setbyspeed.blogspot.com/2011/...ncia-2011.html

To me, smoothness of the inputs or of the car simply means being progressive, it does not mean being slow (car or inputs). For instance, if applied to braking, it could be equated to operating a "valve", not flicking a "switch".

Everything is about balance: Higher speed means higher kinetic energy. The car has a mass and therefore inertia (wants to stay in motion in its direction of travel, or in its current steady state). Braking, accelerating, or turning all require a change of path or speed, and therefore are affected by this inertia. Smoothness will allow to change this path or speed while remaining within the physical limits imposed by the equipment (suspension, tire grip, weight, etc.), and allow the equipment to work as designed.

The proper/fastest line will also be the smoothest. Yeah, it might be a heck of a ride, but the car will be within its limits.

With higher speeds come higher forces and shorter times. Smoothness and balance are still required, but the margins melt away.

Hope this makes sense as written.

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

Quote:

Originally Posted by Skypalace (Post 2549)

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! :D
(Sorry to harp on about this, I've just been thinking about it a lot lately...)

-Christian

Quote:

Originally Posted by Skypalace (Post 2549)

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

Quote:

Originally Posted by TRAKCAR (Post 2478)

Not to steal the thread, (very thought provoking!). To offer incite to the question: "help with terms to use with students". I ask early on what other action sports the student participates in. For instance: If the student golfs, I reference the "cleansing breath" idea that golfers take just before hitting a tee shot which helps with relaxation and focus. I have the student perform this on straight sections of the track to help with tension on track. an example of instruction for a student (at the beginning of a straightaway):

"OK, check your mirrors, gauges, flag stations, take a big breath and let it out"

Any association with other activities that you have in common to the driver student can help drive home a manipulative action or an idea you would like to get across.

I haven't had much luck using this technique unfortunately, primarily because I am not a very sportif person, especially with "action" sports :) I can talk basketball and tennis, that's about it.