Lift-off understeer

[TripleS]

I would quite like to have a ride with 5star.

Some say the spirit of adventure is dead. No it ain't.

Best wishes all,
David.

[5star]

I would quite like to have a ride with 5star.

Some say the spirit of adventure is dead. No it ain't.

If I thought you were serious, that would great.

And in case anybody is serious, I propose to start the drive with standard Roadcraft commentary, and when you're happy with that I then switch to a commentary on what I'm doing to manage the vehicle dynamics. The only reason I can't do both together is because I can't talk fast enough.

So as an example, in town, something like "[Plan] The next hazard I need to deal with is a parked car in my lane, there is one oncoming, so I'm going to use acceleration sense to slow until the oncoming has passed and I have free space to enter the offside. [Action] Mirror, slowing and holding, mirror, going".

Then the same again, it would be "[Plan] I need to first slow, and then bring up my speed and do a double lane change at the same time. This is going to unsettle the vehicle so I need to plan when to use my throttle in relation to when I steer, for comfort and to maximise grip. Slowing is easy as it is in a straight line, but as I move out and steer around the parked car, I want to make sure the majority of my acceleration is completed on the straight before pulling out, and then I'm on maintenance throttle as I steer around the parked car. [Action] Slowing the car now in a straight line on throttle, gear, holding a constant speed while we wait to offside, ensuring I have enough space to accelerate in a straight line, accelerating now in a straight line and reducing to maintenance throttle to ensure I'm not fighting the car as we turn. Hold maintenance throttle as I steer around the parked car. Now after the last turn, as I roll off the steering I'll use the slightest amount of deceleration to help this."


As another example, in the country on a road I don't know, it would be first "[Plan] I'm approaching a left hand bend and my speed is restricted by the limit point, I need to slow for his bend. I want an offside position for visibility, and I'll maintain this offside position until i can see the exit of the bend so I can then plan an apex. [Action] mirror, slow, gear, and taking an offside position to maximise my visibility. Keeping on the throttle as I enter the bend so I can balance the car, waiting for the limit point, OK now I can start to accelerate while taking a late apex to ensure I exit in the centre of my lane. Mirror and check speed."

Then the same again, it would be "[Plan] I'm going to need two parts for this bend, the initial part which is limited by visibility, and then I'm guessing the bend will open up for an acceleration part when I can see the exit. So I want to set the car up to be in a state of oversteer through the first part, so that when I'm ready I can accelerate and the acceleration will assist in turning the car in towards the apex. I'm going to choose this plan because it most matches my experience of this type of bend and we haven't seen any hazard signs on approach. But in case it is a bend that requires a slower 2nd half, or I need to take emergency action, I'm aware that the danger is going to come from lack of grip at the rear, so my priority will be to steer first, and manage speed changes in accordance with grip. [Action] I'm aware that as I approach the car is in a state of understeer. This means it is safe to be aggressive on the brakes if I need, but for now we'll just use gentle acceleration to set the entry speed. Now my entry speed is good, I'm waiting for the turn-in point. Turning the steering wheel now, I'm making this process as long and smooth as possible, waiting for the exact point to seamlessly transition from steering to throttle to put the car into a state of maximum oversteer while increasing speed as little as possible. Now I'll maintain this state of oversteer through the constant part by using as little acceleration as possible, just the minimum amount to stop the car transitioning back to understeer, until the limit point opens up. Now the limit point is moving away and I can plan an apex, so I'll add throttle to help the car turn in towards the apex. If I was in a state of understeer throughout the first part, I'm aware that if I add throttle it would have the opposite effect and push the car towards the offside, so if I messed up the turn-in and didn't achieve an oversteer state, or messed up and didn't apply enough throttle through the first part, I'd instead be needing to decelerate towards the apex to assist the turn."

And, just a reminder, I know road cars to do not oversteer. That is just a word I use in my head. If it offends you, change it to "balance the vehicle so that when I add the smallest amount of throttle it helps the turn rather than hinders it."

[Gareth]

just a reminder, I know road cars to do not oversteer. That is just a word I use in my head. If it offends you, change it to "balance the vehicle so that when I add the smallest amount of throttle it helps the turn rather than hinders it."

I'm sure you understand it's difficult to have a meaningful conversation if the participants have differing definitions for the same word, and that when trying to grapple with the nitty-gritty it's generally better to use the more precise, technical, definitions of words and phrases.

[5star]

just a reminder, I know road cars to do not oversteer. That is just a word I use in my head. If it offends you, change it to "balance the vehicle so that when I add the smallest amount of throttle it helps the turn rather than hinders it."

I'm sure you understand it's difficult to have a meaningful conversation if the participants have differing definitions for the same word, and that when trying to grapple with the nitty-gritty it's generally better to use the more precise, technical, definitions of words and phrases.

Yes, that is all I've been asking.

You are experienced enough to know that in a corner, you can set the car up so that when you come off the gas, the car turns in, and when you get on the gas the car widens the line. I believe it is weight transfer that is causing this.

And I know you are also experienced enough to set the car up so that when you add throttle, it makes the car turn in, and when you come off the throttle it runs wide. I believe it is the direction of the forces generated by the tyre slip angle that does this.

What should I call the first state, and what should I call the second state? Preferably in one word (or as few words as possible)?

[5star]

stuff

Oh, hi. I thought you foe'd me. Well I'm glad you haven't because you do bring a lot to this conversation.

2. If you've got time to say all that in a corner, it's either a very long corner and thus of minimal interest or you can't get all that information across.

I can (and do) say it in my head - or at least I'm aware of it if i'm not actually saying the words. In reality I'm probably going to have to pull over, draw a diagram, talk it through on paper, then do it again just pointing the important bits like the point when I think it is most beneficial to get on the throttle to achieve the [unnamed state where throttle helps turn-in rather than hinders it].

Where it is really important is where there are lots of transitions that happen quickly, like roundabouts, and it is wet or icy.

[5star]

You are experienced enough to know that in a corner, you can set the car up so that when you come off the gas, the car turns in, and when you get on the gas the car widens the line. I believe it is weight transfer that is causing this.

And I know you are also experienced enough to set the car up so that when you add throttle, it makes the car turn in, and when you come off the throttle it runs wide. I believe it is the direction of the forces generated by the tyre slip angle that does this.

What should I call the first state, and what should I call the second state? Preferably in one word (or as few words as possible)?

I'm requoting this again at the bottom, as I suspect people only read the last bit and miss the important bits higher up. Until we can work out what to call these states, I think it will be difficult to go on.

[5star]

You are experienced enough to know that in a corner, you can set the car up so that when you come off the gas, the car turns in, and when you get on the gas the car widens the line. I believe it is weight transfer that is causing this.

And I know you are also experienced enough to set the car up so that when you add throttle, it makes the car turn in, and when you come off the throttle it runs wide. I believe it is the direction of the forces generated by the tyre slip angle that does this.

What should I call the first state, and what should I call the second state? Preferably in one word (or as few words as possible)?

I'm requoting this again at the bottom, as I suspect people only read the last bit and miss the important bits higher up. Until we can work out what to call these states, I think it will be difficult to go on.

Again, I can't go on until we can agree terms to describe the two states.

[jcochrane]

You are experienced enough to know that in a corner, you can set the car up so that when you come off the gas, the car turns in, and when you get on the gas the car widens the line. I believe it is weight transfer that is causing this.

And I know you are also experienced enough to set the car up so that when you add throttle, it makes the car turn in, and when you come off the throttle it runs wide. I believe it is the direction of the forces generated by the tyre slip angle that does this.

What should I call the first state, and what should I call the second state? Preferably in one word (or as few words as possible)?

I'm requoting this again at the bottom, as I suspect people only read the last bit and miss the important bits higher up. Until we can work out what to call these states, I think it will be difficult to go on.

Again, I can't go on until we can agree terms to describe the two states.

I’m no engineer, like StressedDave, and can only speak from my experience.
Your first paragraph sounds like how you can vary the amount of understeer with the throttle when the car balance, steering input and speed are in harmony whilst in the bend.
In your second paragraph I get the bit about a (small (my words)) amount of throttle helps (steering input (more efficient)) when applied just before the initial steering input and that too much throttle will create too much understeer, given a fixed amount of steering input, to eventually cause the car to either loose grip at the front or run too wide but I don’t understand how coming off the throttle makes the car run wide unless you mean that comming off the gas before steering input is applied makes the steering input it less effecient. Or is it that even after lifting off the entry speed is still too high causing the car to run too wide?

Of course negotiating a downhill bend the need is to stop the cars speed getting too high and trail braking helps here.

I don't know whether being more precise ie. what are the phisics as the steering input is apllied when travelling in a straght line or whilst in a bend throttle adjustments are made. On the other hand this might make it all the more confusing.

I'm going to have a lie down.

[TripleS]

I would quite like to have a ride with 5star.

Some say the spirit of adventure is dead. No it ain't.

If I thought you were serious, that would grate.

Well I can't blame you for doubting my seriousness (you don't normally get much of that from me), but I was being serious actually. It was purely out of interest, and not because I feel qualified to help sort out any of your problems, such as they might be.

Just occasionally it occurs to me that it might be nice to have a ride with somebody else, chat about things, and just see what emerges. That's all it was: I wasn't intending to press the matter and make a formal exercise of it.

I guess you really ought to spend some time with SD, and that is a serious suggestion.

[fungus]

Bloody hell, is this thread still going on ?

[TripleS]

You've noticed... He hasn't

The more I see the same paragraph repeated, the more I wonder whether he's after some sort of recognition as a brilliant driver. Sadly, that position is taken on the forum by Dave... The man whose age exceeds the mileage of CUBby.

Eh, what position? I'm not claiming, or even seeking, any particular position. I was told quite clearly some years ago that I wouldn't pass an advanced test, and the verdict didn't surprise me.

Perhaps I'm misunderstanding something again. No matter, it's nothing serious.

Best wishes all,
Dave - aged 194,289 - but on a good day feels nearer 23.

[Astraist]

Of course negotiating a downhill bend the need is to stop the cars speed getting too high and trail braking helps here.

For going downhill, sometimes engaging an even lower gear can allow the driver to keep the car at a constant speed ON the throttle.

I usually find that this facilitates better control on straight and bendy downhill sections.

[Astraist]

Aye, but if you downshift even further, in spite of the slope, engine braking occurs and some throttle needs to be applied to keep it from slowing down more.

In some vehicles, this might require slowing down much more than desired or run in very high revs, but otherwise it allows control of the car to be more intuitive.

[5star]

Of course negotiating a downhill bend the need is to stop the cars speed getting too high and trail braking helps here.

For going downhill, sometimes engaging an even lower gear can allow the driver to keep the car at a constant speed ON the throttle.

I usually find that this facilitates better control on straight and bendy downhill sections.

That's an interesting bending of the laws of physics. Adding torque to something travelling downhill increases the speed.

StressedDave, now you're just being an arse. I'm sure you know full well what Astraist means, along with every other 'advanced driver' on here. And, if you don't, heaven help those you coach.

Sometimes 3rd gear doesn't provide enough engine braking, and 2nd gear provides too much engine braking. So you have two options - 3rd and a bit of braking, or 2nd and a bit of throttle. (Or whatever gears it happens to be).

Are you actually here to encourage people, help people and create a positive, friendly forum to discuss and develop ideas?

And if you and Astraist are best buddies and you're just having a laugh, I apologise, but you need to remember a lot of readers on this Public Forum aren't in your club.

[5star]

I would quite like to have a ride with 5star.

Some say the spirit of adventure is dead. No it ain't.

If I thought you were serious, that would grate.

Well I can't blame you for doubting my seriousness (you don't normally get much of that from me), but I was being serious actually. It was purely out of interest, and not because I feel qualified to help sort out any of your problems, such as they might be.

Just occasionally it occurs to me that it might be nice to have a ride with somebody else, chat about things, and just see what emerges. That's all it was: I wasn't intending to press the matter and make a formal exercise of it.

I guess you really ought to spend some time with SD, and that is a serious suggestion.

TripleS, misquoting me like that is below the belt. People won't necessarily have read what I wrote, and will read your 'misquote' and get the wrong idea.

If I thought you were serious, I would take the time to stop by when I was passing, and we could go out for a run, get some coffee, discuss driving. I didn't think you were serious by all the smilies you placed and I thought you were being sarcastic.

Now, if you really do want to meet up, send me a PM and we'll arrange something. And you can report back on this forum what you think.