Video of NSX-R driven by Senna!

genie47 · Post by **genie47** » Sun Oct 16, 2005 3:03 pm

See how good his HT technique is. Amazing.

May he rest in peace.

http://www.jackals-forge.com/TMP/senna_nsx.avi

MMamdouh · Post by **MMamdouh** » Mon Oct 17, 2005 5:33 pm

nice drive... but why the throttle pedal twitching on corners??

MMamdouh

Audacity Racing · Post by **Audacity Racing** » Mon Oct 17, 2005 6:25 pm

mmamdouh wrote:nice drive... but why the throttle pedal twitching on corners??

MMamdouh

he's "feathering" the throttle...

a car has the most speed ina corner when it at the instant where it loses traction. if the car breaks loose, speed is lost, but i order to maintain a high speed, you have to "feather" (or twitch if you will) on the trottle.

this prevents you from giving the wheels too much power while maintaining a high speed through the corner. you can break loose in small amount without sacrificing major speed, so the idea would be to cross that line (where traction is lost) as little as possible, but staying as close as possible

hope that explains it

kinkyllama · Post by **kinkyllama** » Mon Oct 17, 2005 10:14 pm

Audacityracing wrote:
mmamdouh wrote:nice drive... but why the throttle pedal twitching on corners??

MMamdouh

he's "feathering" the throttle...

a car has the most speed ina corner when it at the instant where it loses traction. if the car breaks loose, speed is lost, but i order to maintain a high speed, you have to "feather" (or twitch if you will) on the trottle.

this prevents you from giving the wheels too much power while maintaining a high speed through the corner. you can break loose in small amount without sacrificing major speed, so the idea would be to cross that line (where traction is lost) as little as possible, but staying as close as possible

hope that explains it

Hmm ive never heard of this. Is this something only done w/ high power cars? Even before the apex in the car you have to have the gas slightly on to be able to push the car through the corner at the very quickest speed possible. If your pushing your car to the limit through a corner... and then let off the gas it will start to slide out of the corner.

Audacity, is this what your talking about?

MMamdouh · Post by **MMamdouh** » Mon Oct 17, 2005 10:22 pm

the NSX is RWD... right? that will make what Audacityracing very logical, practically you are making a "foot controled" traction control to prevent the car from sliding and losing speed.

indeed this is applied on powerful cars where you have enough power to lose rear traction on a clean tarmac track with most of the car's weight forced on the rear end.

on a FWD the story is a little bit different i guess... the car will understeer if the traction is lost and that is more likly to happen if it is a powerful car as the weight of the car is mostly on the rear wheels so the front ones are hardly gripping the road... kinda like the problems VX is having with his 2.0 engine and aggresive driving.

i guess on AWD you can do whatever you want with the throttle as the car will always find the lost grip and keeps on going :twisted:

MMamdouh

Audacity Racing · Post by **Audacity Racing** » Mon Oct 17, 2005 10:26 pm

you have to look at his driving style, he's got a very powerful rear wheel drive car...

when exiting the corner, a rear wheel car will produce massive oversteer if too much power goes to the wheels, at the same time, if there is not enough power, the same thing will happen where the back end breaks loose (due to weight shift as opposed to reduction in dynamic friction). oversteer caused by reduced friction (wheel spin) is the side of that spectrum that produces the fastes way through the corner.

it's an imaginary boundry (see circle of traction). the closer to the limit of breaking free, the faster the car goes :twisted:

when it comes to front wheel drive cars, the same can be said for left foot braking...

in a fwd car, understeer occurrs when exiting the corner (and entering most of the time). to provide power to the wheels while maintaining an appropriate weight balance, you can "feather" the brake along with the gas to keep the weight forward (can produce oversteer, but that's easier to correct and control) and keep power to the ground

i can explain more and whip out some telemetry graphs if need be

MMamdouh · Post by **MMamdouh** » Mon Oct 17, 2005 10:41 pm

by all means do.

MMamdouh

Audacity Racing · Post by **Audacity Racing** » Mon Oct 17, 2005 11:23 pm

this is the circle of traction (sometimes called the circle of friction)

here you can see the direction that forces are applied during travel

ACEELERATION- both negative and positive
if the vehicle is going forward in a straight line, the force is applied to the rear... the front of the car becomes lighter and the rear heavier... this is also why you get thrown into yoru seat

the opposite is true for braking... under perfect braking (strightline) the force is applied forward (why your junk moves around your car when you hit the brakes hard)... the rear becomes lighter and the front becomes heavier

LATERAL ACCELERATION- turning
when the vehicle is in a full wheel lock turn, the forces are applied in the opposite direction than the car is moving (centripital, or centrifugal force). everyone has been thrown into the passenger seat when they turned hard

**note** perfect lateral acceleration (turning) is a condition where there is no change in vehicle speed.

to keep the vehicle under control, you must remain INSIDE the circle... i'll show an example...

you can see that if you braked 100% and turned 100% you would lose control... you are outside the circle.

this circle represents the imaginary line i was talking about... as the car accelerates, it loses it's ability to be controlled, as the car turns, it loses it's ability to be accelerated (slowed or sped up)
-------------------------------------------------------

you can make this graph 3D by applying the weights of the car. by placing the car's center of gravity on the center of the circle, you can determine handling characteristics. you can do some pretty easy trig and figure out how the weight will shift under each circumstance (assuming you know the corner weights and location of the center of gravity).
-------------------------------------------------------

one final note (for now)... the size of the circle is determined by the surface , the tires being used, weight, CG, and downforce (driving weight). in the picture below, you can see that wet and icy asphualt SIGNIFICANTLY reduce the size of usable traction.

HOPE THIS HELPS

Audacity Racing · Post by **Audacity Racing** » Mon Oct 17, 2005 11:41 pm

now... to explain his feathering...

he was trying to maintain a perfect turn and throttle for the degree of turning he was performing...

he was trying to stay inside the green circle... by going outside the circle of traction you loose speed by having to correct. by "feathering" the throttle and steering he was able to keep this close area for the turn.

the car may have broken traction 1,000,000 times in that turn, but he always dialed it back in.

the car may have dropped below optimum speed, but he "feathered" to get the car back to optimum speed (considering the turn)

vjx987 · Post by **vjx987** » Tue Oct 18, 2005 1:29 am

the video was nice, i understand the twitching but all those diagrams you have, im lost with those.

genie47 · Post by **genie47** » Tue Oct 18, 2005 1:54 am

It is good to see the video sparked off discussion of how Senna did what he did rather than get locked over videos of how he died.

genie47 · Post by **genie47** » Tue Oct 18, 2005 3:53 am

Actually there are more videos.

Just go here:

http://www.jackals-forge.com/lotus/

A hot favorite is this video of Sabine Schmidt in an M5 chased by a 996.

Video here: http://www.jackals-forge.com/lotus/movies/sabine.WMV

It is 106MB.

MMamdouh · Post by **MMamdouh** » Tue Oct 18, 2005 10:44 am

nice chase

... i got one vid for an older porsche chasing an M3 on this same track and it is very cool... will try to upload it when i get back home.

i also noticed on this vid and the one i have home that the brakes tends to make this shudder sound when pushed hard and this sound is very similar to the sound i had on my old rotors... it seems that this sound is normal afterall...huh?

MMamdouh

MMamdouh · Post by **MMamdouh** » Tue Oct 18, 2005 11:33 pm

here it goes, porcha chasing M3... listen carefully to the brakes

http://www.megaupload.com/?d=527XX9IX

MMamdouh