Handling at the limit vs. intuitive (seat-of-the-pants) handling
01-29-2010, 04:03 PM
#1
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Handling at the limit vs. intuitive (seat-of-the-pants) handling
The other day, I was taking a sharp right hand turn into a parking lot. I was doing about 30 mph. I routinely take this corner without using the brake. The 993 (or any car) will scrub off speed in the corner to where upon exiting the turn I'm doing maybe 23 or 25 mph.
I got to thinking about the Skip Barber High Performance Driving School I took at Lime Rock Ct. 10 years or so ago. At that school, they train you to extract maximum (or they say "safe" (lawyers and all)) performance from any car. During the ground school, they show you how all cars do essentially the same thing. Accelerate, decelerate, understeer, oversteer, or both (a slide). And how all cars can either provide 100% for braking, turning or accelerating. Once you get to 100% of any of these, there is zero % left for any of the others. Then you spend two days or so exploring the limits (in my case it was a BMW 325) on a course with cones rather than real (i.e. "hard") objects in your way.
I mention this as on some occasions, there are other cars following me into this parking lot. It always amazes me how there can be one car length between my car and the following one, then after the turn, I've opened up a three car length opening. Clearly, the following car has applied its brakes to slow down for the corner.
In fact, any car (perhaps the exception being one with bald tires on a wet day) could do exactly as I do, not use the brake and stay one car length behind me.
But most drivers react to the car's "leaning" upon entry into the curve. They are not exploiting any of the built in "margin" in the handling of their car.
The 993 corners so flat that the driver most often does not feel the "seat-of-the-pants" forces and leaning of the car thus applying the brake and slowing down.
In real racing (I've done a little), you don't even think of the forces acting on your body. Instead, you are exploring the limit of your cars adhesion to the tarmac. All you focus on is getting the proper line through the corner and not sliding off the pavement.
This just illustrates the difference between handling at the limit and "seat-of-the-pants" intuitive handling. Most "normal" drivers react to the g-forces while driving and most often drive so far below their car's "limit" as to on a curvy road become an obstruction.
Every 911 I've owned brings out the "devil" in me. You just don't think of "normal" driving (unless blocked by traffic) in a 911.
I got to thinking about the Skip Barber High Performance Driving School I took at Lime Rock Ct. 10 years or so ago. At that school, they train you to extract maximum (or they say "safe" (lawyers and all)) performance from any car. During the ground school, they show you how all cars do essentially the same thing. Accelerate, decelerate, understeer, oversteer, or both (a slide). And how all cars can either provide 100% for braking, turning or accelerating. Once you get to 100% of any of these, there is zero % left for any of the others. Then you spend two days or so exploring the limits (in my case it was a BMW 325) on a course with cones rather than real (i.e. "hard") objects in your way.
I mention this as on some occasions, there are other cars following me into this parking lot. It always amazes me how there can be one car length between my car and the following one, then after the turn, I've opened up a three car length opening. Clearly, the following car has applied its brakes to slow down for the corner.
In fact, any car (perhaps the exception being one with bald tires on a wet day) could do exactly as I do, not use the brake and stay one car length behind me.
But most drivers react to the car's "leaning" upon entry into the curve. They are not exploiting any of the built in "margin" in the handling of their car.
The 993 corners so flat that the driver most often does not feel the "seat-of-the-pants" forces and leaning of the car thus applying the brake and slowing down.
In real racing (I've done a little), you don't even think of the forces acting on your body. Instead, you are exploring the limit of your cars adhesion to the tarmac. All you focus on is getting the proper line through the corner and not sliding off the pavement.
This just illustrates the difference between handling at the limit and "seat-of-the-pants" intuitive handling. Most "normal" drivers react to the g-forces while driving and most often drive so far below their car's "limit" as to on a curvy road become an obstruction.
Every 911 I've owned brings out the "devil" in me. You just don't think of "normal" driving (unless blocked by traffic) in a 911.
01-29-2010, 04:44 PM
#2
Great thoughts! Thanks for posting them. I've often thought there should more training along those lines for anyone getting a license to drive. Lots of people on the road could avoid collisions in challenging situations if they had more awareness of the forces involved (like what percentage of adhesion you allocate to turning, stopping, etc) Many only know to hit the brakes when they feel like things are not in their control, which we all know can be very unhelpful in certain conditions (particularly in rear-weight-biased cars). For example, those that don't know how to drive on ice will lock-em-up and hold them there not realizing that they need to restablish traction to stop most effectively.
Recently a lady in a minvan was driving across the main road on a cross street and forgot to stop at the sign. When she saw me approaching she panicked and hit the brakes, placing her minivan square in my lane. The right thing to do would have been to continue forward to avoid the collision but instinct told her to stop. Fortunately Porsche makes cars with with good brakes or I'd be surfing the classifieds for a replacement.
I understand that many people don't think in terms of physics or performance, and don't really care because they want to just get into their toaster or refrigerator-shaped people-mover and be somewhere. But a little more knowledge could help those who do think about what they are doing and save a few lives, and prevent the rest of us from getting so frustrated when someone clearly doesn't "get it."
Cheers,
Craig
Recently a lady in a minvan was driving across the main road on a cross street and forgot to stop at the sign. When she saw me approaching she panicked and hit the brakes, placing her minivan square in my lane. The right thing to do would have been to continue forward to avoid the collision but instinct told her to stop. Fortunately Porsche makes cars with with good brakes or I'd be surfing the classifieds for a replacement.
I understand that many people don't think in terms of physics or performance, and don't really care because they want to just get into their toaster or refrigerator-shaped people-mover and be somewhere. But a little more knowledge could help those who do think about what they are doing and save a few lives, and prevent the rest of us from getting so frustrated when someone clearly doesn't "get it."
Cheers,
Craig
Last edited by craig.cootsona; 01-29-2010 at 06:46 PM.
01-29-2010, 04:44 PM
#3
I daily drive my 993 and about once a month I find myself having a bit too much fun and needing to correct for oversteer 
My experience (and I have only done one real SCCA race as a novice, and then I ran out of $$) is that instead of relying on the forces you feel, the rumbling of the wheel for understeer, the sound of the tires loosing grip in the rear, and other vibrations are really where the "seat of the pants" kicks in.
Its more about paying %100 to what your car is telling you, both through acceleration/deceleration and other noises and vibrations.
I don't recomment treating the street as a racetrack, but when conditions allow, and you are in a 993 its hard not to have a bit of fun every now and then...
-reiner
My experience (and I have only done one real SCCA race as a novice, and then I ran out of $$) is that instead of relying on the forces you feel, the rumbling of the wheel for understeer, the sound of the tires loosing grip in the rear, and other vibrations are really where the "seat of the pants" kicks in.
Its more about paying %100 to what your car is telling you, both through acceleration/deceleration and other noises and vibrations.
I don't recomment treating the street as a racetrack, but when conditions allow, and you are in a 993 its hard not to have a bit of fun every now and then...
-reiner
01-29-2010, 05:58 PM
#4
Drifting
I don't think most drivers ever experience driving anywhere near the limits which is fine until you need those skills. I went to my first autocross this year. Its a high speed course and it was a totally new experience learning to drive the car at and beyond its limits (and mine). I've been driving for 30 years. There is alot of enjoyment and a sense of accomplishment learning to control a vehicle, especially a Porsche, during performance driving maneuvers. I now have much more respect for what can happen quickly if you push too hard. I would love to get the car on the track with an instructor and learn even more in a safe environment. This knowledge is transferable to daily driving IMHO as it just makes me a better driver should these skills be called upon.
01-29-2010, 06:27 PM
#5
Race Car
I think that seat of the pants (feeling what the car is doing) is very important. But is not the only thing you need to focus on. A good race driver will use ALL the available "data" to make a decision on what the next "input" is.
So they are relying on sight, sound, the vibrations through the steering wheel as well as the feeling through their butt. To ignor anyone of these will be to the detriment of his lap times or worse to the car itself.
When talking about "the limit" and comparing a race car and a street car there are a number of factors that need to be looked at. One of the major limiting factor when it comes to a street car (besides tires, suspension etc) is the seats and seat belts. In a street car you are not held firmly in the seat and will tend to slide around, so going into a corner you turn left, and you slide in the seat right, its only when you stop sliding that you feel what the car is doing. If during that time the car has started to slide, there is a moment that you actually don't know what is going on with the car. At this point most people react (overreact) and tend not to catch the car smoothly.
When you are strapped into a race seat with harnesses, there is little or no movement of your body relative to the car, you feel exactly what the car is doing and you are able to react with the appropriate "input" to correct or get on line.
I do alot of instructing (over 30 events a year) and most people say when they come for a ride in my own car (harnesses and race seats)
A: They always comment that they feel "connected" to the car and
B: they tend not to feel car sick as they are not sliding from side to side...
A good driver will use all available information to feel connected to the car, once anyone masters this they will become great.
So they are relying on sight, sound, the vibrations through the steering wheel as well as the feeling through their butt. To ignor anyone of these will be to the detriment of his lap times or worse to the car itself.
When talking about "the limit" and comparing a race car and a street car there are a number of factors that need to be looked at. One of the major limiting factor when it comes to a street car (besides tires, suspension etc) is the seats and seat belts. In a street car you are not held firmly in the seat and will tend to slide around, so going into a corner you turn left, and you slide in the seat right, its only when you stop sliding that you feel what the car is doing. If during that time the car has started to slide, there is a moment that you actually don't know what is going on with the car. At this point most people react (overreact) and tend not to catch the car smoothly.
When you are strapped into a race seat with harnesses, there is little or no movement of your body relative to the car, you feel exactly what the car is doing and you are able to react with the appropriate "input" to correct or get on line.
I do alot of instructing (over 30 events a year) and most people say when they come for a ride in my own car (harnesses and race seats)
A: They always comment that they feel "connected" to the car and
B: they tend not to feel car sick as they are not sliding from side to side...
A good driver will use all available information to feel connected to the car, once anyone masters this they will become great.
01-30-2010, 03:02 AM
#6
Rennlist Member
Somewhere last year I read a comment from a suspension design guy working for one of the manufacturers. His take basically was that the average idiot (my term) gets nervous, and feels they are losing control when the g-force hits--.4g! Consider that a '65 Chevy truck on bias plies probably pulls 50% better than that, and you've got the disconnect.
To Steven's point above, I've taken out absolutely clueless-to-track-driving "rookies" in the Radical and subjected them to ~2g's. (Very tire condition dependent.) Have yet to have one passenger tell me to slow down.
To Steven's point above, I've taken out absolutely clueless-to-track-driving "rookies" in the Radical and subjected them to ~2g's. (Very tire condition dependent.) Have yet to have one passenger tell me to slow down.
