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-   -   Lessons to learn from track cam footage? (errors spins crashes ) (http://forums.pelicanparts.com/off-topic-discussions/867715-lessons-learn-track-cam-footage-errors-spins-crashes.html)

sugarwood 05-31-2015 05:52 PM

Lessons to learn from track cam footage? (errors spins crashes )
 
VIDEO #1:
He seemed to lose control well before the turn.
What did this guy do wrong?

Was he going too fast? 4th gear was said.
Yet, he seems to be going the same speed as the car ahead of him.

Is the lesson here to brake a lot more before the turn,
and then use throttle once in the turn?

<iframe width="420" height="315" src="https://www.youtube.com/embed/AoBQLuvr9-o" frameborder="0" allowfullscreen></iframe>

TimT 05-31-2015 05:56 PM

That is an oldie but a goody...

Turned way to early, and either lifted or braked to early...

And his narrative will be no help to anyone..

TimT 05-31-2015 06:01 PM

BTW the car is a Subaru

sugarwood 05-31-2015 06:16 PM

VIDEO #2: Is it risky to slalom at 75mph?

<iframe width="560" height="315" src="https://www.youtube.com/embed/_lsDkIEAJms" frameborder="0" allowfullscreen></iframe>

Nostril Cheese 05-31-2015 06:21 PM

Nemesis!

VaSteve 05-31-2015 06:39 PM

Quote:

Originally Posted by TimT (Post 8646007)

Turned way to early, and either lifted or braked to early...

And his narrative will be no help to anyone..


Yes.



Quote:

Originally Posted by sugarwood (Post 8646037)
VIDEO #2: Is it risky to slalom at 75mph?


That guy was behind the car the moment he started. Watch him turn and let go of the wheel. It was just a matter of time.




It's very hard to analyze video for what exactly went wrong. You can often see early turn ins, but hard to tell if track is wet, etc. Usually the guy providing the commentary is the one that crashed, so that's of little help. When I'm in the right seat, I can feel the car pushing, watch a tentative driver, hear sketchy throttle application, etc. Video only tells you part of the story.

HardDrive 05-31-2015 07:02 PM

More driving, less douchebag grandstanding.

LeeH 05-31-2015 07:30 PM

Quote:

Originally Posted by TimT (Post 8646007)
That is an oldie but a goody...

Turned way to early, and either lifted or braked to early...

Yep. The 911 is tracking out while the Subie is still turning in. You can hear the tires start to complain but he doesn't react. His butt was telling him things were about to go bad, but he wasn't listening. Could be he was focused on catching the Targa instead of driving his own car.

#2 is some fine quality video. Obviously, he's going too fast, but his fatal error occurred when he snaps the wheel hard to the left on the cone before the one he crashed on upsetting the car's balance.. Violated rule #1 of fast driving... be smooth on the inputs. With the correct input for his speed, he'd have clobbered the next two cones, which would have been a much better choice than the trip off-road and into the trees.

#2 reminded me of some very valuable advice I got at one of my very first SCCA autocrosses many years ago. An old man came up to me after a run and said something like: "Son... I've been watching you and you've got a lot of potential. But if you'd slow down a bit you'd be a *****-pot faster." :)

rattlsnak 05-31-2015 08:09 PM

geez, thats a fast track to be tached out in 3rd gear for an AX. Even before he slid off I was looking at that treeline.

sugarwood 05-31-2015 08:25 PM

Yea, I just noticed #2's sudden jerk on the wheel that made him lose control.
Note to self: Don't jerk the wheel, especially when going fast.

Are there times where you have to let go of the wheel?
Or should you never let go of the wheel? (At least as a rookie AX/DE guy)

sugarwood 05-31-2015 08:28 PM

Quote:

Originally Posted by LeeH (Post 8646166)
Yep. The 911 is tracking out while the Subie is still turning in.

What does "tracking out" mean?

I watched #1 again.
Is turning a bit too early such a huge error that you end up crashing?

This video kind of concerns me.
#1 did not suddenly jerk the wheel or do anything reckless.
Once he was in oversteer, he corrected his steering.
Meanwhile, he totaled his car and could have gotten hurt or killed.
I was under the impression AX and DE are somewhat safe, but I am rethinking that.

John Rogers 05-31-2015 08:37 PM

I learned to road race with a motorcycle in the early 70's and the old guy that taught me had several pieces of advice. They also hold true when road racing a car, no matter what brand it is. In no particular order they are: the straighter you can make a curve, the better and faster it will be, do not be afraid to use the whole road surface, never brake when turning (although this can be modified now with the new cars and ABS), either be braking or accelerating, anything else is wasted time and space, never try to follow the back end of an old guy that was a pro once as you'll never be as fast as he is (or she) and finally you'll never win the race on the first lap but you sure as hell can loose it!

porsche4life 05-31-2015 08:54 PM

#2 is a PCA autocross in OKC. I wasn't there that particular day but I've seen a few f ups and they were almost always preceded by someone seriously over driving the car. Hell I've done it myself, just was lucky I enough to not munch the car. I'll post some more videos of the track later. It has tons of runoff space in most places...


As has already been noted, he was out of control before he even got into the slalom.

LeeH 05-31-2015 10:01 PM

Quote:

Originally Posted by sugarwood (Post 8646250)
What does "tracking out" mean?

I watched #1 again.
Is turning a bit too early such a huge error that you end up crashing?

This video kind of concerns me.
#1 did not suddenly jerk the wheel or do anything reckless.
Once he was in oversteer, he corrected his steering.
Meanwhile, he totaled his car and could have gotten hurt or killed.
I was under the impression AX and DE are somewhat safe, but I am rethinking that.

Tracking out = unwinding the steering wheel after the apex.

It's hard to tell from the grainy, video that cuts out right as he starts to spin, but to me, it looks like the car is understeering as he enters the fateful corner.

If you watch the earlier corners you'll see him hold the wheel turned a bit more than it should be as the front tires skid. He says at the beginning that he's too hot in the corner and that he backs off the gas to bring the rear around. Also, it appears the car is porpoising a bit at the very beginning. In other words, the car bounces up and down on its own through a constant radius turn despite no change in steering input. You can see it, but also hear the skidding tire sound rise and fall in the first 5 seconds of the video.

Watch the steering wheel at the :31 second mark. He gives the wheel a slight twitch to the right while the car is already understeering. If he applied the "back off the gas" theory at the exact moment he twitched the wheel, the car's weight is going to transfer to the front tires (that are pointing too far to the right already) causing them to hook up resulting in a clockwise polar rotation.

Whether on the track or in a parking lot, it's still car racing. Autocrossing in a parking lot is probably about as safe as it's going to get... assuming you choose a parking lot without trees. :D

<iframe width="420" height="315" src="https://www.youtube.com/embed/b5JEo4haM_k" frameborder="0" allowfullscreen></iframe>

sugarwood 06-01-2015 04:52 PM

Does a bad suspension cause the porpoising ?
This hopping caused turning instability that wasn't related to the driver, right?

porsche4life 06-01-2015 05:16 PM

That mustang was just a victim of a driver ate up with dumb

TimT 06-01-2015 05:19 PM

Why not check out some videos of drivers doing it well?? You can learn from that also...

For example.... a shake down a few years ago after a refresh.... I think it was a 1:00 lap in traffic

Lime Rock lap

And then of course there is an awesome start at Roebling

Roebling start

And of course Watkins Glen...

The Glen

Moar

More Glen

LeeH 06-01-2015 05:20 PM

Quote:

Originally Posted by sugarwood (Post 8647564)
Does a bad suspension cause the porpoising ?
This hopping caused turning instability that wasn't related to the driver, right?

Shocktek's Michael G. O'Callaghan further explains the problems encountered by most street cars: "Typically, when the shocks are at the end of their life cycle, the rod seal will fail (hopefully slowly) and the shock absorber fluid will leak out. The damping characteristics of these aged shocks are not good: the overall damping forces are much lower, the damping curves have changed and there may be air in the shock which may act like a spring. Bottom line: wheel hop, uncontrolled porpoising, excessive body roll. Very dangerous in a collision avoidance maneuver. [Source]

A930Rocket 06-01-2015 06:14 PM

What an awful place for an AX. Never should have been held there.


Quote:

Originally Posted by LeeH (Post 8646352)
Tracking out = unwinding the steering wheel after the apex.

It's hard to tell from the grainy, video that cuts out right as he starts to spin, but to me, it looks like the car is understeering as he enters the fateful corner.

If you watch the earlier corners you'll see him hold the wheel turned a bit more than it should be as the front tires skid. He says at the beginning that he's too hot in the corner and that he backs off the gas to bring the rear around. Also, it appears the car is porpoising a bit at the very beginning. In other words, the car bounces up and down on its own through a constant radius turn despite no change in steering input. You can see it, but also hear the skidding tire sound rise and fall in the first 5 seconds of the video.

Watch the steering wheel at the :31 second mark. He gives the wheel a slight twitch to the right while the car is already understeering. If he applied the "back off the gas" theory at the exact moment he twitched the wheel, the car's weight is going to transfer to the front tires (that are pointing too far to the right already) causing them to hook up resulting in a clockwise polar rotation.

Whether on the track or in a parking lot, it's still car racing. Autocrossing in a parking lot is probably about as safe as it's going to get... assuming you choose a parking lot without trees. :D

<iframe width="420" height="315" src="https://www.youtube.com/embed/b5JEo4haM_k" frameborder="0" allowfullscreen></iframe>


widgeon13 06-02-2015 04:23 AM

The first vid is a little more than a spin and the one autocross in the trees is just ridiculous.


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