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Senna in the NSX

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  • robburgoon
    replied
    Sounds an awful lot like "guess and check" to me, you guys sure he's not just checking how much grip there is in a place where he won't lose much time while he checks it?

    Leave a comment:


  • Red Mist
    replied
    At about 1:00, Johnny Herbert explains it. Seems all F1 drivers did it, until Shumi brought left foot brake and throttle.
    [http://www.youtube.com/embed/5EJ0N7rqsRQ]Michael Schumacher Turning Technique - YouTube[/url]
    Last edited by Red Mist; 01-05-2012, 01:51 PM.

    Leave a comment:


  • emilio700
    replied
    Originally posted by J. Tyler View Post
    Help me out. What am I missing? I think my point is pretty irrefutable: He only does it mid-corner, mostly before the apex. That pretty much debunks your theory, Emilio. On top of that, if your theory was correct, he'd be doing the exact same thing with the brake pedal. But he isn't.

    You guys have a source to the throttle-jabbing-in-an-F1-car claim? (Written by someone who knows WTF they're talking about, not some journalist...?) Only time that *might* make sense is in a turbo car.
    Not theory. I use the same technique, about 1% as often as Senna did though. Optimum slip angle, in every direction, not just longitudinally along the vehicle centerline. As Andrew clarified, Senna was playing with all the hysteresis in the driveline and control systems. Even an F1 car has some hysteresis, particularly in the early turbo days. Later on though, you can with Senna driving the N/A Williams you can still hear him employing the same technique occasionally.

    If the driver just pins it, tires break traction and he flies off the track. If he chops the throttle, he coasts to a stop. If he adjust throttle in perfect sync with available grip, he maintains optimum slip angle. Or does he? I recall seeing friction circle plots of F1 drivers; two with a wild, wheel sawing, tail out driving style then compared to smoother, more economical styles. One wild F1 driver inexplicably exceeds the verified maximum steady state G for that car during a long lurid slide at near WOT with a flurry of pedal and steering inputs. The smoother F1 driver didn't reach the same peak but had more area under the tested limit. The lesson there, to me at least, is that the probing, and forcing the car past it's steady state limit by tapping the throttle allowed Senna to stay closer to the car's actual (not theoretical) traction limits.

    So it's exactly the same as the traction technique the Harleys used via hysteresis of the driveline and torque pulses. Very much like ABS or traction control but more to control lateral grip. Come to think of it, OEM stability controls pulse the brake or diff when controlling yaw rate. They have a PID feedback loop, just like we have in our heads.

    Proportional - Give and input based on previous data (your memory or table in data base)
    Integral - Measure result of input
    Derivative - Change your input next time to get closer to target

    That's a poor explanation of PID control theory but you get the idea. Senna jabs the throttle, audibly pausing, changing amplitude and frequency according to grip. I can't do that for more than one or two feedback loops in a 150whp Miata because I'm mortal. He did it for two hours in a 1000whp F1 car because he was from another planet. Probably why he openly despised stability control systems in F1 cars. I think he said once (paraphrased), that a "Monkey could drive an F1 car" with all the computer controls extant at the time.

    I recall a friend who saw Senna at the Phoenix F1 race. Senna dominated that event. He also extensively used the throttle tapping thing, like every turn, every lap. The slower the turn, the more he did it.

    As I've said before, a good driver does not have too many preconceived notions of what inputs the car needs. That driver should have a reference point based on experience and good judgement but be able, and willing to adapt and experiment to find ways to to try to extract more performance than might otherwise be theoretically or logically possible. Senna was doing what he thought would be the fastest thing, and it usually was.

    Go through the old Senna in car videos on youtube, particularly the ones from street circuits with slow turns. You'll see it.

    Leave a comment:


  • gixxer_drew
    replied
    Also, several drivers I have worked with have attempted to duplicate his technique never worked for them though. They came across it in their studies as well actually I was kind of surprised you weren't aware. I can admit that I have found myself doing something similar before when I was driving off road .. I did go faster I am willing to attribute it to placebo just as easily as a physical effect. At the end of the day if Senna went quicker while doing just about anything they'd have let him. We will never truly understand this, just guess.

    Thinking about it more now... I think I saw a log trace from it in one of my DAQ books.

    Leave a comment:


  • gixxer_drew
    replied
    Jeff, I collected information on Senna and his drive techniques over years of study and various sources and I cannot recall exactly which one I got that from. I just whore information and collect it all to clack around in my brain until i get too old to remember it all.

    Leave a comment:


  • J. Tyler
    replied
    Originally posted by gixxer_drew View Post
    Jeff, like Emilio said, he did that in F1 as well.
    Originally posted by emilio700
    You'll figure it out eventually
    Help me out. What am I missing? I think my point is pretty irrefutable: He only does it mid-corner, mostly before the apex. That pretty much debunks your theory, Emilio. On top of that, if your theory was correct, he'd be doing the exact same thing with the brake pedal. But he isn't.

    You guys have a source to the throttle-jabbing-in-an-F1-car claim? (Written by someone who knows WTF they're talking about, not some journalist...?) Only time that *might* make sense is in a turbo car.

    Leave a comment:


  • emilio700
    replied
    Originally posted by J. Tyler View Post
    Emilio, don't mean to be rude, but that sure sounds like a bunch of nonsense. A tire has an optimum slip angle for a given circumstance, period. That's why F1 and other series developed such bad-ass traction control systems that operate(d) at very high frequencies - to keep the tire *right* at its peak grip. Think about braking: a good driver in a non-ABS car does not "pump" the brake pedal rapidly to make the tires stay at optimum slip angle; he quickly loads up the tires right to their ideal slip angle, feels out the limit, and holds the tires there at the peak. It's the same thing with acceleration. If what you were saying is true, Senna would be jabbing at the brake pedal too. Or sawing at the steering wheel, for that matter.

    On top of all that, Senna was doing the throttle-jabbing in the middle of corners, not coming off of them. Putting power down coming off the corners, he is very steady & progressive with the throttle (like a proper driver should be), while making small adjustments & oversteer corrections with the steering wheel (again, like a proper driver should). The jabbing was virtually all done mid-corner (usually before the apex, actually). I guarantee you he is doing that to play with the car, get a feel for things like the diff, overall mid-corner balance, etc.

    And the power stroke of a Twin or 2-Stroke motorcycle engine overpowering the rear tire on a bike has absolutely no corollary to anything any human driver can do with the throttle pedal of a car. That is happening at a WAY higher frequency than anything a human can do with their ankle. The closest you can get to that is probably a mountainbiker going up a steep hill and slightly overpowering the rear tire with each leg stroke.

    Cheers.
    You learn fast. You'll figure it out eventually

    Leave a comment:


  • gixxer_drew
    replied
    Originally posted by emilio700 View Post
    Senna used the throttle tapping technique in the lower formulae and F1. Pretty well documented. He's simply controlling slip angle and wheel spin. Pretty common in rally and off road racing.

    The closest corollary I can draw is two motorcycle related bits of trivia.

    Harley Davidson 72° offset pin V twins had dominated American dirt track racing from it's inception well into the 80's. By the 70's the top bikes were making like 95whp. Yamaha found a way to get a TZ750 into a frame and legal to race in dirt track. The lightweight TZ750 inline 4 two stroke was a 150whp beast with a light switch powerband. The TZ750 only won a few races despite having a massive weight and power advantage. Yamaha engineers eventually figured out that the odd firing pulse of the Harley's wherein two power pulses followed one right after another then both coasted through the induction stroke made the difference. That moment when the the flywheel was coasting through the induction strokes for both cylinders would let the tire hook up on the dirt. Yamaha later developed a V twin with somewhat asymmetric firing order and started wining races.

    In the last 15 years, GP/Moto GP bikes evolved from freaky high hp (250whp+) with even firing to lower powered motors with offset firing. The high power even firing bikes had reached the limits of how much power they could put down. The first offset firing two strokes made less power and had an odd droning exhaust note. These were then known as "big bang" motors as they had most of the power strokes concentrated in one part of the cycle then cylinders coasting through the induction phase. Same basic concept as the 72° Harley's and successful for the same reason. Eventually traction control and 4 stroke powerbands have eliminated the need for the uneven firing engines.

    So Senna is keeping the tires at optimum slip angle both laterally and longitudinally. As Andrew opined, he is playing with system reaction times but it's not just the electronic systems. In the '92 NSX, there were none anyway. Rather he's adding torque to bring the tires to optimum slip angle then cutting torque before it overloads the tire and pushes it beyond optimum slip angle.

    I do it on occasion but it's usually just one or two little blips when I feel the tires going past optimum slip angle and I don't feel that making a steering correction will result in the best speed. I see lots of fast guys do this occasionally as I do, but no where near as often as Senna did.


    oh and Loeb is the GOAT. :dons flame suit:
    Jeff, like Emilio said, he did that in F1 as well. Emilio, yeah i was counting tires as system reaction times but I dont think I am placing as much emphasis on them as you are. The electrical system reaction times are too short for a human (even senna) unless you are talking about a control system. I'm thinking tires, driveshafts, throttle plates, air moving past throttle plates, things like that. Don't forget Senna drove F1 in the turbo era.

    Dyno is a great place to observe these kind of things.
    Last edited by gixxer_drew; 01-04-2012, 10:05 PM.

    Leave a comment:


  • momofoolio
    replied
    Originally posted by emilio700 View Post
    Senna used the throttle tapping technique in the lower formulae and F1. Pretty well documented. He's simply controlling slip angle and wheel spin. Pretty common in rally and off road racing.

    The closest corollary I can draw is two motorcycle related bits of trivia.

    Harley Davidson 72° offset pin V twins had dominated American dirt track racing from it's inception well into the 80's. By the 70's the top bikes were making like 95whp. Yamaha found a way to get a TZ750 into a frame and legal to race in dirt track. The lightweight TZ750 inline 4 two stroke was a 150whp beast with a light switch powerband. The TZ750 only won a few races despite having a massive weight and power advantage. Yamaha engineers eventually figured out that the odd firing pulse of the Harley's wherein two power pulses followed one right after another then both coasted through the induction stroke made the difference. That moment when the the flywheel was coasting through the induction strokes for both cylinders would let the tire hook up on the dirt. Yamaha later developed a V twin with somewhat asymmetric firing order and started wining races.

    In the last 15 years, GP/Moto GP bikes evolved from freaky high hp (250whp+) with even firing to lower powered motors with offset firing. The high power even firing bikes had reached the limits of how much power they could put down. The first offset firing two strokes made less power and had an odd droning exhaust note. These were then known as "big bang" motors as they had most of the power strokes concentrated in one part of the cycle then cylinders coasting through the induction phase. Same basic concept as the 72° Harley's and successful for the same reason. Eventually traction control and 4 stroke powerbands have eliminated the need for the uneven firing engines.

    So Senna is keeping the tires at optimum slip angle both laterally and longitudinally. As Andrew opined, he is playing with system reaction times but it's not just the electronic systems. In the '92 NSX, there were none anyway. Rather he's adding torque to bring the tires to optimum slip angle then cutting torque before it overloads the tire and pushes it beyond optimum slip angle.

    I do it on occasion but it's usually just one or two little blips when I feel the tires going past optimum slip angle and I don't feel that making a steering correction will result in the best speed. I see lots of fast guys do this occasionally as I do, but no where near as often as Senna did.


    oh and Loeb is the GOAT. :dons flame suit:
    Emilio explains the big bang theory better than any text book I've ever read XD

    I sometimes blip the throttle mid-corner too to help the car rotate and I found myself doing it more with unpredictable condition such as rain!!
    I don't do it as much in dry condition/ running at tracks that I'm familiar with..
    but I find this technique very useful whenever traction is uncertain in front of you =)
    Last edited by momofoolio; 01-04-2012, 09:24 PM.

    Leave a comment:


  • J. Tyler
    replied
    Originally posted by emilio700 View Post
    Senna used the throttle tapping technique in the lower formulae and F1. Pretty well documented. He's simply controlling slip angle and wheel spin. Pretty common in rally and off road racing.

    .
    .
    .

    So Senna is keeping the tires at optimum slip angle both laterally and longitudinally. As Andrew opined, he is playing with system reaction times but it's not just the electronic systems. In the '92 NSX, there were none anyway. Rather he's adding torque to bring the tires to optimum slip angle then cutting torque before it overloads the tire and pushes it beyond optimum slip angle.

    I do it on occasion but it's usually just one or two little blips when I feel the tires going past optimum slip angle and I don't feel that making a steering correction will result in the best speed. I see lots of fast guys do this occasionally as I do, but no where near as often as Senna did.


    oh and Loeb is the GOAT. :dons flame suit:
    Emilio, don't mean to be rude, but that sure sounds like a bunch of nonsense. A tire has an optimum slip angle for a given circumstance, period. That's why F1 and other series developed such bad-ass traction control systems that operate(d) at very high frequencies - to keep the tire *right* at its peak grip. Think about braking: a good driver in a non-ABS car does not "pump" the brake pedal rapidly to make the tires stay at optimum slip angle; he quickly loads up the tires right to their ideal slip angle, feels out the limit, and holds the tires there at the peak. It's the same thing with acceleration. If what you were saying is true, Senna would be jabbing at the brake pedal too. Or sawing at the steering wheel, for that matter.

    On top of all that, Senna was doing the throttle-jabbing in the middle of corners, not coming off of them. Putting power down coming off the corners, he is very steady & progressive with the throttle (like a proper driver should be), while making small adjustments & oversteer corrections with the steering wheel (again, like a proper driver should). The jabbing was virtually all done mid-corner (usually before the apex, actually). I guarantee you he is doing that to play with the car, get a feel for things like the diff, overall mid-corner balance, etc.

    And the power stroke of a Twin or 2-Stroke motorcycle engine overpowering the rear tire on a bike has absolutely no corollary to anything any human driver can do with the throttle pedal of a car. That is happening at a WAY higher frequency than anything a human can do with their ankle. The closest you can get to that is probably a mountainbiker going up a steep hill and slightly overpowering the rear tire with each leg stroke.

    Cheers.

    Leave a comment:


  • ucfbrett
    replied
    Originally posted by emilio700 View Post
    Senna used the throttle tapping technique in the lower formulae and F1. Pretty well documented. He's simply controlling slip angle and wheel spin. Pretty common in rally and off road racing.

    The closest corollary I can draw is two motorcycle related bits of trivia.

    Harley Davidson 72° offset pin V twins had dominated American dirt track racing from it's inception well into the 80's. By the 70's the top bikes were making like 95whp. Yamaha found a way to get a TZ750 into a frame and legal to race in dirt track. The lightweight TZ750 inline 4 two stroke was a 150whp beast with a light switch powerband. The TZ750 only won a few races despite having a massive weight and power advantage. Yamaha engineers eventually figured out that the odd firing pulse of the Harley's wherein two power pulses followed one right after another then both coasted through the induction stroke made the difference. That moment when the the flywheel was coasting through the induction strokes for both cylinders would let the tire hook up on the dirt. Yamaha later developed a V twin with somewhat asymmetric firing order and started wining races.

    In the last 15 years, GP/Moto GP bikes evolved from freaky high hp (250whp+) with even firing to lower powered motors with offset firing. The high power even firing bikes had reached the limits of how much power they could put down. The first offset firing two strokes made less power and had an odd droning exhaust note. These were then known as "big bang" motors as they had most of the power strokes concentrated in one part of the cycle then cylinders coasting through the induction phase. Same basic concept as the 72° Harley's and successful for the same reason. Eventually traction control and 4 stroke powerbands have eliminated the need for the uneven firing engines.

    That's an outstanding analogy. The 72-degree V-twin derived from a 16 cylinder radial aircraft engine. It was, to oversimplify it, two cylinders plucked and bolted to a motorcycle frame (obviously they had to cast a new crankcase and other bits, but that was gist of the engineering). The radial aircraft engines used to fire sequentially in a 360 degree manner, which is why the Harley fires both cylinders, then waits an entire crankshaft revolution before it can fire again. It's also why they vibrate so much.

    In addition, as you rev a Harley, the crankshaft inertia pushes the back of the frame downward, which is why many of the dirt trackers were hard tails. The engine increased traction with rpm.

    Leave a comment:


  • bawareca
    replied
    Originally posted by Richard EVO View Post
    Just like I do it in my NSX, but I wear a helmet.
    Probably it didnt look dangerous enough to him to put his helmet on.
    On the other note,today it is not political correct to not wear a helmet(and HNS).

    Leave a comment:


  • emilio700
    replied
    Senna used the throttle tapping technique in the lower formulae and F1. Pretty well documented. He's simply controlling slip angle and wheel spin. Pretty common in rally and off road racing.

    The closest corollary I can draw is two motorcycle related bits of trivia.

    Harley Davidson 72° offset pin V twins had dominated American dirt track racing from it's inception well into the 80's. By the 70's the top bikes were making like 95whp. Yamaha found a way to get a TZ750 into a frame and legal to race in dirt track. The lightweight TZ750 inline 4 two stroke was a 150whp beast with a light switch powerband. The TZ750 only won a few races despite having a massive weight and power advantage. Yamaha engineers eventually figured out that the odd firing pulse of the Harley's wherein two power pulses followed one right after another then both coasted through the induction stroke made the difference. That moment when the the flywheel was coasting through the induction strokes for both cylinders would let the tire hook up on the dirt. Yamaha later developed a V twin with somewhat asymmetric firing order and started wining races.

    In the last 15 years, GP/Moto GP bikes evolved from freaky high hp (250whp+) with even firing to lower powered motors with offset firing. The high power even firing bikes had reached the limits of how much power they could put down. The first offset firing two strokes made less power and had an odd droning exhaust note. These were then known as "big bang" motors as they had most of the power strokes concentrated in one part of the cycle then cylinders coasting through the induction phase. Same basic concept as the 72° Harley's and successful for the same reason. Eventually traction control and 4 stroke powerbands have eliminated the need for the uneven firing engines.

    So Senna is keeping the tires at optimum slip angle both laterally and longitudinally. As Andrew opined, he is playing with system reaction times but it's not just the electronic systems. In the '92 NSX, there were none anyway. Rather he's adding torque to bring the tires to optimum slip angle then cutting torque before it overloads the tire and pushes it beyond optimum slip angle.

    I do it on occasion but it's usually just one or two little blips when I feel the tires going past optimum slip angle and I don't feel that making a steering correction will result in the best speed. I see lots of fast guys do this occasionally as I do, but no where near as often as Senna did.


    oh and Loeb is the GOAT. :dons flame suit:

    Leave a comment:


  • Bueller
    replied
    Originally posted by GreyFocus View Post
    both vids, great at the limit driving
    Really?

    Leave a comment:


  • J. Tyler
    replied
    Originally posted by gixxer_drew View Post
    There's been a lot of debate over the years about his technique. I suspect the secret is that he isn't fighting the traction, he's working with the system reaction times.
    I think he's just not used to a heavy/floaty street car, on street tires with no grip and huge slip angles, so he's feeling it out. Gokart/Formula car guys always have a hard time hopping in a street car for the first time and driving it properly because everything is so floaty & vague compared to what they know.

    So, I think he's just feeling out the car, playing with it; being a little over-stimulating with his throttle/brake inputs on purpose just to get a reaction out of the car to see what it does (notice how he has a huge lockup at the end of the front straight in the red car).

    $.02

    *Edit: He also has a weird miss-shift moment in the white car, which further tells me he was just hopping in for a lap or two and was not fully comfortable with the car yet.
    Last edited by J. Tyler; 01-04-2012, 06:16 PM.

    Leave a comment:

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