Spun It!

[Rory]

he may have been bragging of a 360, he may have only spun 45 degrees, and took advantage of the roundabout situation, and just drive peacefully the rest of the way round it, then turned off his required exit, thus equalling 360 degrees? :D

just a thought

[loggyboy]

Perhaps hes confusing 180 with 360?

[oldcro]

Quote from Vyer's post

"At the end of the road there is a roundabout, so i was braking hard dropping down the gears, but i don't think i slowed down enough....

as i entered the roundabout, still hard on the brakes, i dropped it into second, the car was carrying too many revs etc.

So from that I read you entered the roundabout at a speed to much to stop "i entered the roundabout, still hard on the brakes" . Too many revs in second gear proves this. My post was to raise your awareness of the potential dangers of what you did. It does sound like you realise your error and have learned a valuable lesson at little or no cost to yourself or others. Good for you.

Some of the initial posts did upset me with their comments of hard luck and drifting school type messages. I just hope you gain from the experience and become a better driver, and that does not mean faster by the way.

[loggyboy]

I bet you're an 'advanced driver' aren't you? :P lol

[WylieCoyote]

I bet you're an 'advanced driver' aren't you? :P lol

I am. That's why advanced drivers can see the dangers - particularly blues and twos cos we're trained to recognise hazards and react before they become problems. Everyone should do advanced driver training, it might make the roads a bit safer.

[oldcro]

I bet you're an 'advanced driver' aren't you? :P lol

YES.

[Rikos]

Quote from Vyer's post

"At the end of the road there is a roundabout, so i was braking hard dropping down the gears, but i don't think i slowed down enough....

as i entered the roundabout, still hard on the brakes, i dropped it into second, the car was carrying too many revs etc.

So from that I read you entered the roundabout at a speed to much to stop "i entered the roundabout, still hard on the brakes" . Too many revs in second gear proves this. My post was to raise your awareness of the potential dangers of what you did. It does sound like you realise your error and have learned a valuable lesson at little or no cost to yourself or others. Good for you.

Some of the initial posts did upset me with their comments of hard luck and drifting school type messages. I just hope you gain from the experience and become a better driver, and that does not mean faster by the way.

The posts about 'drifting lessons' upset you! Why? These comments where not serious and didnt mean that Vyker should have lessons and then attempt the roundabout again to see how you cope at the same speed.

They where meant in jest as that is what the majority of comments posted try to be to lighten up peoples day. Not once has someone said 'unlucky Vyker, learn from your mistake and then have another go and nor has anyone condoned the behaviour and so i feel you getting upset is seriosuly unnecessary.

[WylieCoyote]

Can everyone just kiss and make up? I hate bickering

[Rikos]

No intention of bickering just wanted to straighten out the matter, i hope oldcro doesnt take my comments as a personal attack as it's not meant this way.

Everyone knows me and i'm not nasty i prefer to try and make people laugh (mainly by eating hot chili's)

[WylieCoyote]

(mainly by eating hot chili's)

I'm sure you'll be well aware of what I mean then if I were to say to you 'Japanese flag'!!!

[Rikos]

(mainly by eating hot chili's)

I'm sure you'll be well aware of what I mean then if I were to say to you 'Japanese flag'!!!

Absolutely!!! Althouhg i did amaze the crowd by taking it like a man ............... a very feminine man that wears womens clothes!

[WylieCoyote]

(mainly by eating hot chili's)

I'm sure you'll be well aware of what I mean then if I were to say to you 'Japanese flag'!!!

Absolutely!!! Althouhg i did amaze the crowd by taking it like a man ............... a very feminine man that wears womens clothes!

What about the blubbing, thumb sucking and calling for your mum then?!!! Oh wait, that was me!

[Tony-Bones]

Sorry i have to disagree with most of the comments here so far.... Speed albeit a contributing factor was not the criminal here... The failure was the human and the car.

[Rikos]

You've gone and done it now Tony

[Tony-Bones]

You've gone and done it now Tony

Oh well.... Opinions are one thing, facts are another.... If the opinions tend toward lift-off-oversteer, polar centres and tyre saturation limits then lets have the facts to complete the picture.... Ever more so to defend Vyker and his innocent warning to LOC members about his experience.

[DJ Wozza]

You've gone and done it now Tony

maybe we should start with the "my dad can have your dad" or " see you behind the bike sheds after School" comments

:winky:

[loggyboy]

Sorry i have to disagree with most of the comments here so far.... Speed albeit a contributing factor was not the criminal here... The failure was the human and the car.

I agree.. partly, i cant see how the car (unless through failure of a component) an ever be blamed.

[Tony-Bones]

Sorry i have to disagree with most of the comments here so far.... Speed albeit a contributing factor was not the criminal here... The failure was the human and the car.

I agree.. partly, i cant see how the car (unless through failure of a component) an ever be blamed.

Your question is absolutely valid.... The chassis itself is not necessarily to blame more the Human operating it, but there is a need to understand the relationship...

When we talk about chassis dynamics we often talk about a car chassis as though it’s a singular thing, but actually when trying to think about technical aspects of either driving a chassis or it’s design that’s actually incorrect and unhelpful.

The car chassis is in reality just a collective term for a group of independent mechanical sub-systems. Most people are of course just interested in the driving so are only concerned with the net result of all of the sub-systems performing together as one. The unfortunate effect is that this makes it quite hard for these people to explain themselves clearly when talking to technical engineers who are in place to change the chassis set-up to suit them.

Understanding each and every one of the individual sub systems certainly does go a very long way to help in understanding exactly how a car chassis works, but understanding how all of these sub-systems interact with one another really is the Holy Grail of chassis dynamics.

So if we begin to think of the chassis in fact just as a complicated mechanical system we can take a look at other mechanical systems in general and start to apply the universal sciences and truths involved in systems engineering.

To avoid going into a great deal of depth talking about harmonics I think it’s best now if we can just except for the time being that systems have a natural frequency (actually they have more than one, that’s a discussion for another time) and that these natural frequencies of the system are determined by the systems stiffness.

The primary frequency of a car chassis will normally be very low and measured in Hertz or Hz for short, this description is historically used in science to indicate cycles per second.

Ok now for the bit we actually care about, the effect of the chassis’s primary natural frequency. In real life this frequency dictates the minimum level of chassis correction or inputs per second required from the driver in order for the car to stay on its intended path.

For example:

A Rolls Royce might typically be set-up with a natural frequency of around 0.65hz, meaning that you can be very lazy when driving this car and it will still follow it's prescribed path.

A Mitsubishi Lancer EVO which is fairly typical of the aggressive sports saloon car market, might have a natural frequency of around 1.8hz meaning that the driver must give inputs at a rate of just under 2 adjustments per second, that’s quite a work rate.

In the extreme a formula 1 car is typically set at 4.5-4.8hz frequency, that’s a MINIMUM of almost 5 adjustments per second!

I consider the Lexus to be around 0.70 or 0.80 unmodified, so she is a lazy lady indeed.

[janet]

Wow ! Amazing how such a tetchy thread suddenly is interesting!! Thanks Doc for that......Is it a co-incidence that since taking your medicine, my lazy lady has not swung out her ample behind like she used to ??

[loggyboy]

Blimey, that is an interesting read.

Id still argue that the car cant be blamed. Despite whatever the cars attitude is, like you said at the begining, its down to the the human to understand that relationship. A car cant be blamed for its setup (whether its factory or modified), a driver should know its limits (or at least endeavour to learn them and take the consequences when exceeding them). Its also up to the driver to tweek the car to suit their required style, but shouldnt expect the car to do anything but obey the laws of physics.

If the frequency of a car is low then it may make a car 'easier' to drive but the driver needs to know that if they push a 'lazy' car like the lexus its going to bite as it then cant react to the split second inputs required for on the limit control.

A high freq may require more inputs from the driver to remain in control, but when on the limit it those inputs will allow greater control.

When I drive the lexus on the limit I know it has to be in different style to the way I would drive my nova on the limit, ths Nova is much more forgiving, just cuz its setup (albeit basically) for handling not comfort.

[Tony-Bones]

Blimey, that is an interesting read.

Id still argue that the car cant be blamed. Despite whatever the cars attitude is, like you said at the begining, its down to the the human to understand that relationship. A car cant be blamed for its setup (whether its factory or modified), a driver should know its limits (or at least endeavour to learn them and take the consequences when exceeding them). Its also up to the driver to tweek the car to suit their required style, but shouldnt expect the car to do anything but obey the laws of physics.

If the frequency of a car is low then it may make a car 'easier' to drive but the driver needs to know that if they push a 'lazy' car like the lexus its going to bite as it then cant react to the split second inputs required for on the limit control.

A high freq may require more inputs from the driver to remain in control, but when on the limit it those inputs will allow greater control.

When I drive the lexus on the limit I know it has to be in different style to the way I would drive my nova on the limit, ths Nova is much more forgiving, just cuz its setup (albeit basically) for handling not comfort.

The problem with the modern car is that it drives you? Most "feed back loops" are denied until Yaw is exceeded beyond mechanical saturation limits.... Human perception is an interesting equation>

In order to truly understand chassis dynamics we must understand both sides of the Car vs Driver partnership. We must essentially listen to the chassis’s side of the story and then the driver’s side of the story. When we get this right we produce a capable chassis that is easily exploitable by the intended driver.

The human element of chassis dynamics is without doubt the most important and the hardest aspect for engineer’s to understand, the consequence is that this area of the science is often totally ignored and leads to drivers being blamed for poor skills or lack of commitment, either that or an acceptable outcome is eventually totally fluked via hours of trail and error.

The driving process:

• Step one: A driver looks at the oncoming road and estimates the required inputs to complete the task at hand, we make this estimate based on a model of the car held in our memory, the more accurate this model the more accurate our initial guess.

• Step two: An “Open Loop” input is made according to our guess

• Step 3: Then “Closed Loop” trimming modifies these inputs to take account of emerging conditions or errors in the initial guess

There are 3 main channels of feed back used for “Closed Loop” driving

1. Visual feedback

2. Inner ear (yaw rate, lateral acceleration etc) feedback

3. Muscle tension or Steering wheel torque feedback

It is through these communication channels that a car can speak to a driver.

Ok firstly, the drivers eyes….

Processing visual stimuli is actually quite a complex procedure and incurs a delay of around 600msec in most people between seeing and understanding, so that’s a maximum update rate of around 1.8Hz

Driving by your eyes alone is only possible if no quick action is required.

• If the roads and bend radius's are known and learned

• And of course as long as no chassis control task’s are required

The inner ear….

Processing the yaw and latt acc information from the inner ear is a far simpler process and is therefore faster but even so this feed-back process still suffers a delay of around 300msec so this loop can actually update at around 3.2Hz which is pretty fast.

Muscle tension in the drivers body….

The task of moving the steering wheel is a function carried out by the brain stem, the brain stem works automatically to maintain the correct steering angle by varying your arms muscle tension. Changes in the steering resistance cause the brain stem to get confused and flag up the problem to a higher part of the brain that is responsible for processing the overall task of driving the car. This form of feedback is extremely fast at around 100msec so this can provide you feedback at 10Hz (ten times per second).

Some interesting points to note:

• A driver’s in-head car model is almost exclusively linear

• Excessive anxiety in a driver can easily cause the steer torque mechanism to be completely “swamped” by muscle tension and therefore useless.

• Inexperienced drivers are frequently unable to interpret inner ear signals or are too confused to act on them so they are discarded by the brains automatic information filters in the brain stem

• A surprising level of confusion exists in the inner ear between yaw and chassis roll, this lead some drivers to “dislike” body roll

• Many drivers are found to revert back to an entirely visual driving strategy in emergency circumstances

• Many drivers are overwhelmed and lose control even though the car was capable of completing the manoeuvre

• A maximum practicable hand steering wheel rate is around 1100 degrees / second –but not for long

• Typical hand wheel rates are much slower - < 100 degrees / second in “Sensible” driving

All this and we haven't even offered a reason why the rear rotated Geometrically..... Interesting stuff though don't you think.

[Unregistered_User]

Makes me smile as it only seems to be these sort of posts that Monsieur OldCro posts upon.

Anyways, glad to hear both the car and owner are well amigo. So many contributing factors, just learn from the approach to the roundabout and the experience of it - resolve the problem and move on :)

All the best,

Jamie

[oldcro]

Makes me smile as it only seems to be these sort of posts that Monsieur OldCro posts upon.

Anyways, glad to hear both the car and owner are well amigo. So many contributing factors, just learn from the approach to the roundabout and the experience of it - resolve the problem and move on :)

All the best,

Jamie

Thank you for that Jamie, your wrong of course and a read of my last 10 posts would show this. As for Vyker there was just one contributing factor, he entered the roundabout too fast, made a mistake and learned from it. Better to read (my sort of posts) than that someone has had a serious accident. But then, I do not have the benefit of your experience, and I'm not even French Monsieur.

[oldcro]

No, I am really p***ed of with Jamie's snide remark. So tell you what Jamie, print off Vykers original post, show it to a Police Traffic Officer and ask his/her opinion of the driver involved. I look forward to hearing what the reply is, and will accept his answer without reservation.

[Tom-18]

Yeh because Traffic Police know everything........ Some of the most hypocrytical drivers on our roads today. Because there always safe and never Speed!

Must admit apart from the bickering this has been a really interesting read!!

And gald Vyker and his car are ok!

Tom.