Lies, damn lies and Roadcraft

[Martin A]

In another post StressedDave said there is plenty wrong with Roadcraft.

Any chance of making this STICKY so its faults can be listed. Hopefully its editor will become aware of this. Perhaps then when it is re-written the faults can be corrected or at the very least omitted. Let's start off with the fairly basic one below.

Page 56 Braking or accelerating as you go round a corner or bend reduces the amount of control you have over your vehicle.

[martine]

OK I'm in danger of showing my ignorance here amongst those who know better...but (for any QI fans I feel a siren about to sound!)...

...if you're being pendantic I suppose it reduces the amount of available grip rather than 'control'...is that what you're getting at?

[James]

Accelerate too much in a Noble M12 GTO 3 and the back end will flickout as you have asked too much of the tyres, sending the car into a rear wheel skid.

Accelerate too much in a Ford Mondeo ST 220 3.0 V6 and the front tyres will lose grip, sending the car forward and into a front wheel skid.

I don't agree with the notion that Roadcraft dictates it's Tyre Grip Trade Off to link in with Limit Point Analysis. They are 2 totally different things.

But of course, who cares what I think...

[SbT]

This discussion will ultimately only be resolved empirically, not through argument. What hard data is available apart form the 87% figure and where does it come from?

SbT
IAM Member

[SbT]

StressedDave wrote:

There's a hell of a lot of wrinkles when you start considering tyre behaviour, suspension setup and the like, but as a first order estimate, it's not that bad

.

Excellent, thanks. But isn't the whole problem that there are so many variables involved - driver, speed, how hard you brake in the corner or accelerate, handling characteristics of the car, road surface etc that it's better to try to avoid any braking/accelerating that may affect control, even if only marginally in most instances?

I can say with absolute certainty that if I brake in a corner driving my motorhome the effect on stability is marked whereas in my car it would be much less noticeable - although obviously I have never done this since becoming a mere IAM Member

SbT
IAM Member

[James]

I agree

[7db]

Consider Dave's unofficial second mantra

Daily.

Is all the power going on to a fixed level prior to starting to turn-in? Ie is accelerative down to mildly accelerative as the car settles into the turn.

What's wrong with adding more and more power in the corner? Is it just that we might run out of vision (esp if corner tightens) or is it that we'll re-promote understeer?




* Dang - can't figure out necessarily which -- think u/s as weight transfer away from front is dominant factor...rather than grip use at rear (since I still have 85% left...). A big lumpy dollop of power will probably promote o/s, but that's a different matter.

[SbT]

StressedDave wrote:

The bigger risk is reaching a speed at which you can no longer stop in the distance you can see to be clear

I think this is the biggest risk of all. If I'm at the correect speed for the corner in terms of being able to stop in the distance I can see to be clear why would I want to accelerate and thus risk not being able to do so.

It's all interesting but in the end i think we are descending into pedantry!

SbT[/quote]

[7db]

You've driven with me, what do you think...

I had my eyes closed at the time...

I think what I'm doing is setting the power before starting to turn-in and then gradually increasing the power through the corner to exit (up to WoT and remove deflection). I'm wondering whether I ought to be a little more conservative with power application...or allow this build up through the corner.



SbT - sorry if you feel this isn't relevant, but I do.

[James]

The smooth application of constant drive is all that is needed to balance the vehicle around the bend. It does not necessarily need increased power unless the limit point starts to run. Just watch the limit point and be guided by it.

I wonder if anyone will agree with what I have said? Little ol' me.

[James]

I love you Dave, I read all your comments but never understand a word! We must meet for a coffee one day.

Whats this corner, where is it? I work at EK... don't know of any bad corner.

In like a tortoise out like a hare!

[vonhosen]

I love you Dave, I read all your comments but never understand a word! We must meet for a coffee one day.

Whats this corner, where is it? I work at EK... don't know of any bad corner.

In like a tortoise out like a hare!

I don't think the bend he is talking about is in London.

B1090 towards Abbots Ripton perhaps.....only StressedDave will know for sure (& us if he chooses to share).

[James]

He is a very knowledgable chap this dave isn't he Von? I think he is part scientist, part AI. The thinks he speaks off would make Isaac Newton proud.

O Stressed one, can you devise some commentary suggestions based on your infinate wisdom? Would there be any sentence short enough to cover a gradual bend?

Waiting excitedly.

[7db]

I love you Dave...We must meet for a coffee one day.

Looks like someone's lucky day.

B660 contains the corner of fun. The fun bit if figuring out which one it is before you leave the road...

[vonhosen]

And db was right the bend is on the B660. They've just tried to re-engineer it by removing the bend sign and replacing it with lots of nice plastic poles. I presume that the thinking is to discourage people from accelerating because the first part of the bend is relatively open and focus them on the bit that suddnely tightens.

Can't think of any on the B660 worse than the one on the B1090 at the moment. I'll have to go for a drive.