Decreasing radius corners
 

Have been practicing my heel toe and feel decent with it now in a straight line. But now my problem is decreasing radius corners. It seems some lateral force of cornering makes it hard for me to modulate the pedals. For example corner starts at around third gear ~70 and by the time I'm off the brakes is ~35, so I am trying to hit second gear.

Is it just simply a practice practice practice thing? Any tips?

I'm having trouble conceptualizing what you're trying to do. If you're talking about heel and toeing while trail braking, don't bother with it. You'll do much better braking harder while pointing straight and getting the car set up before you enter the corner. If you're having trouble on corner exit, turn in later.

There a golden rule of motorcycling that really applies across all disciplines of racing.
"Once the throttle is cracked open it is rolled on smoothly and continuously throughout the remainder of the turn."

You are exactly right, I downshift to the entry speed gear and am trying to downshift again during the turn so I can be in the proper gear for the exit speed.

You don't want to be shifting at all while turning. Upshifting can cause snap oversteer at the limit while the rears are likely to lock when you downshift. Coming out of a corner you want to be in the proper gear to hit redline at the end of track out. If at any point durning the corner you hit redline you'll want to take it one gear higher

On "my" track we have a tricky corner with a steep downhill braking and turn-in that tightens throughout the corner, along with the compression of coming out of the downhill and starting the ascent. I basically brake HARD in the straight bit and then turn in while trailbraking. I don't have time and skill enough to do any heel-n-toe in that situation, and I'm doing fine.

This is the entry to the first part of the corner:
[ame="http://www.youtube.com/watch?v=4iOxAz2T0i0"]NM racing GT serie nye rudskogen 2011 angsten 2 - YouTube[/ame]

Incar a few years back, not in the '86, though.
[ame]http://youtu.be/Cv2QSOvmz1c?t=24s[/ame]

Incar with the '86. Har to see the road, but you can see what I'm doing. I have logs from the run if you're interested. Sorry about the camera. (1:10 in this video, start time doesn't work for some reason)
[ame]http://youtu.be/SoRZtuxWMS8?t=70s[/ame]

Here's the trackmap. We're talking about T3 and T4 which are taken as one corner.
http://shortcarracing.no/wp-content/...udskogen-1.jpg

@atledreir, I think you are hijacking this thread, but you can see that that the other cars get 2 downshifts in a straight line. You are only at 5k rpm on your first downshift, you need to get another downshift while still in a straight line. It's a long brake zone, you have plenty of time. You're still slowing down at the second downshift and if you were going "fast" you'd be upsetting the car.

I imagine the same applies to OP.

Why is this thread, of all things, in off-topic?

man that VW driver is horrible

amazing track though

two ways to handle a decreasing radius turn to maximize efficiency.. and they depend on what type of corner follows this corner.

if the corner is followed by another corner, then you brake during cornernering (trial braking)

if the corner is followed by a straight, then you simply turn the decreasing radius corner into a constant radius corner.... (see below)


Trailbraking is difficult to do right and requires the most skill, you do some of your braking in the straight line coming up to the turn but then use the initial wide part to continue to slow down (with the brake) until the "exit portion" aligns itself to your speed and trajectory... in the image blow, imagine the red line, but you're braking during most of it so that when you get to the right side you're pointing down into the right direction and can get back on the gas.

if you start at 70 and end at 35, consider heel-towing into 2nd before you start your turning... also a clutch kick and a proper shift are two different things, you can shift mid corner, just do it gently

if you've got a straight after this, then you need to maximize exit speed and for this you create your own "perfect corner" on top of the existing, physical corner

you do this by staying wide and bombing deep into the corner, creating imaginary apexes for yourself........... i'm having a hard time explaining this, better in person, but here is a picture... the green line is what you're aiming for

http://image.sportrider.com/f/179797...approaches.jpg

@7th Gear

Perfect...I was gonna say the classic...

"Sacrifice entrance speed for exit speed"

Your diagram shows that perfectly/ I do a lotta canyon/mountain roads.

you instinct/vision makes you see the beginning line and take it too fast. Once you come up on the decreasing radius you realize you have to scrub too much speed. On a motorcycle, this is a terrifying conclusion.

You have to use your road/track knowledge to take the proper line.
Great post...illustrates it perfectly.

i think youre ignoring the initial issue in that its not that easy to be going 70 in 2nd gear. if that was possible i dont think he would be having a problem.

i'd like to see the specific course in question... but i would say if the difference is that drastic then simply shift mid corner, if he's going all the way down to 35mph then there is little risk of clutch kicking even if he does fumble it

just blip the throttle hard and you'll be fine

That double apex line will kill your brakes and tyres in no time! I keep looking at it at going "ugh".

during lapping yeah it will kill you, but might be a good aggressive passing line... maybe? i don't do door-to-door racing :/

I think it will cause a lot of consternation to the guy you are passing. You essentially cut him off and then slow down the pace due to the amount of heavy braking and then possibly slower exit speeds.

The ideal line is best as it gives you better options and retains best overall speeds.

I always plan a line backwards. I start with where I want to be and draw a line that involves straights as much as possible from the exit end.

So if A was your entry point, B is the apex, C is the final exit point, I work from C and draw a straight line and then try to work in a curve with the least amount of turning (turning = speed loss).

I apply that thinking into autoX and road rallying. Usually I think its best line but it's not like I film myself and then get people to comment.

That picture was specifically relating to motorcycles. The blue line would be your typical overtaking manoeuvre under brakes.

So without sitting down and Meditating like a Buddha about this; everything in my race car driver being says:

Always blue line.. ALWAYS BLUE LINE. Always blue line.
Always blue line.. ALWAYS BLUE LINE. Always blue line.
Always blue line.. ALWAYS BLUE LINE. Always blue line.
Always blue line.. ALWAYS BLUE LINE. Always blue line.


Always blue line.. ALWAYS BLUE LINE. Always blue line.

So many advantages to the blue line.
A: you initiate your turn SO MUCH LATER which means you can brake SO MUCH STRAIGHTER and SO MUCH DEEPER which means you're SO MUCH FASTER all while driving less distance. And on a side not, so much safer because straighter. It's a lot easier to modulate brakes and threshold when your car isn't "cornering".

B: And you're tires? Well you're tires are going to thank you because you won't be asking them to do two things as once like the green line would require. The whole point about going around a track quickly is to turn less. The green line literally has a braking zone pointed away from the corner. That's ridiculous.

The blue line is somewhat of a "point and squirt" line but at the point you apply the throttle you're at the same relative angle you would be with the green line and according to the diagram specifically, you'll have the same exit speed. The green line "looks" quicker due to the more open radius but as the blue and green cross over the radius for the green tightens up which means that car is not rolling until AFTER the point the blue and green have overlapped and thus has almost no exit speed advantage, at least none that would make up for the massive gap the blue line would have put on him before apex.

Door to door: Do the blue line. At apex of this corner per this diagram, you will make up car lengths on the driver running the green line, lap after lap after lap.

If I'm following a driver taking the green line, he's getting passed.
If I'm being followed the Blue Line is also great defense.
If I'm being followed and he takes the green line, I will gap him.

Ideally, the blue line would be slightly away from the first apex and the exit would be wider all the way to driver left (track out) to help broaden the radius overall improving turn in and apex speed.

Now, internet... Tell me I'm wrong. :D





I love racing.

yes and no..

the blue line is the trailbraking line more or less and would require perfect rotation at the pivot to not waste the time you saved by cutting straight through, you will be traveling at a slower speed at that point, and you're going to have to accelerate from a slower speed to try and catch up to the green line

i would argue that the blue line is better for higher powered cars that can be rotated well using steering inputs while the green line is for "momentum" cars that can sustain higher loads... cuz even if you take the longer path, if you're significantly faster through out.. you'll still come out on top.

cuz if you do the blue line in a car with no low-end power, you better hope to god that you land PERFECTLY into your power range when you hammer down, otherwise you'll be losing everything that you gained.


So yes, the blue line is the faster line if your car is perfectly setup for such an approach, particularly your gearing, because you'll need to accelerate harder from a much lower speed... so it would most certainly be track dependent.

the green line however is the safer and more consistant line, it is also the perfect demonstration of how to mentaly attack a decreasing radius corner that would otherwise be giving you conflciting signals.

Un momento.. adding to your diagram....



:loading:

7th Gear: I hope you don't mind a little editing of your diagram. ;)

Some elaboration on why I like the blue line.

http://img.photobucket.com/albums/v8...pproaches1.jpg



Look at the purple line, think of that purple dash mark as "the corner" because it really is that point that really matters.

So let me talk about the green line now.

A: Angle of entry: The green car will have to initiate it's braking earlier than the blue car and in this diagram do so while pointing away from the corner. That is ridiculous unless you're setting up for a drift. If you're goal is to get at an apex why would you start by driving away from it? (rhetorical). Look at where the orange dashes are. There's a bit of an optical illusion here. Up to the point of the "orange zone" the green car is carrying more speed but in this orange zone it's radius narrows so it will have to slow for that and since it was approaching this narrow part of it's radius while it was already cornering that means the driver had to leave enough tractive force in his tires to allow for some braking for this orange zone. Because of this the green car has sacrificed its corning speed leading up to it.

B: Safety: Braking in a straight line is far safer than braking while cornering. For any rookie, having them enter a corner in which they have to balance the tractive delta between slowing and turning can easily lead to an off-track excursion.

C: Corner Exit speed: As you can see the lines in between those dashes share roughly the same radius which means both cars are making the same turn. The purple dash is roughly where the driver would be rolling on the throttle. Both cars are on roughly the same radius and exit as they roll on to the throttle to leave the corner.

Now, let's talk about that blue line.

A: Since the braking event is much straighter the braking can be done much later and much harder which means the car is traveling at a faster rate of motion for a longer period of time before the braking event. The green car has to slow down less initially, then make a large right hand radius, then slow again to make the decreasing radius. If the green car isn't doing 2 slowing "events" then that is one hell of a trailing braking maneuver, and time is being left on the table.

B: The blue line needs to be further towards driver left on entry. This means the initial braking event can be even straighter and harder and lead to a more open radius trail-braking corner entry.

C: Both lines exit incorrectly. They should both track out all the way to drivers left as illustrated.


Thank your putting up with me. :D

i hope you realize that the above diagram was something i randomly pulled out of google


and again, you're failing to account to a myriad of other possible data that we're not aware of such as the type of straight that came before and what type of straight (or corner) is gonna come after, i'm not sure what it is that you're trying to argue... that the blue line is always better?

I'm a little bit of newbie here. I might argue point C. Only because you don't know what the next turn is. I think where you point to "apply throttle" is correct, but to add to it, its subjective on how much. If the track straightens some, then you can apply more throttle and drift to the left.

But if you have a turn coming up to the driver's left, if you apply too much throttle and drift to the left, then you'll just pinch yourself and screw up the following turn.

The big thing to remember, when setting up a corner is to make sure you exit in position for the next corner.

a long time ago I read this article on trail braking in a racetrack environment.. and I think it best I leave it here for everyone to ponder on


http://hpdedriver.files.wordpress.co...trailbrake.pdf

so rice_classic is absolutely right in that in theory a proper use of trailbraking and full commitment to corner entry and exit will provide an optimal time

but the reality is that this is much harder to perform on a consistent basis than one would think..

particularly when you have to understand that you are not simply taking a tighter line, braking deeper, rotating, then applying throttle... to execute the parabolic line correctly you need to initiate rotation during entry using brake and steering inputs, otherwise you simply wont have the space needed to rotate your car , it's limited by it's own steering angle.... shits hard mang! and at 100+kph is scary too... i'm not at that level yet.. one day, maybe.

Those radii don't even look close to roughly the same. The green car can definitely go through faster.

If you move the corner exit out, the green car can maintain speed as that will stretch the radius out a little.

Neither line, as drawn, is ideal. The green line takes the scenic route through, the blue line should be out wider at the corner entrance, and neither track far enough out at the exit. The blue line allows you to brake straighter, later, and deeper as well as getting hard on the gas much earlier than the green line does. The blue line will have a slightly lower speed at turn in but allows you to get on the gas much harder earlier. The blue line will also be easier on your tires than the green line because the duration of time that the tires are fighting lateral G is much shorter.

The green line, as drawn, leaves you open to having someone run up the inside with nothing you can do about it aside from slamming into the other person mid corner. While the blue line, as drawn, is sacrificing some mid corner speed to close off the inside.

Ah, but will the Blue car and the Green car be traveling at the same VELOCITY when they reach the point where they would be rolling on the throttle. I'm thinking the Green car will be traveling markedly faster and, thus, will have a "jump" on the Blue car out of the corner. The Blue car is just then exiting a much tighter and slower corner, despite now being on the same exit radius of the Green car.

I dunno, but it looks that way to me.

Having said that, I'm not so sure but what Rice's Blue car might be turning quicker lap times. It would depend on what preceded and followed this turn. If this turn followed a long, high speed straight, the Blue car would make up a lot of precious time in the approach, able to maintain a much higher speed for a longer time, albeit down into the apex of a (artificially generated) much sharper corner.

It would be interesting to observe video of this in real time.

The Blue car is clearly on the optimum passing line if he's trailing the Green car into the corner. He'll get to the purple throttle application point before the Green car and will "take away the line" from the Green car despite going slower at that point. The Green car may be going faster at that point, but will be effectively blocked from exploiting that advantage.


But, the issue at the moment is which of these lines will yield the best lap time independent of passing strategies.

Practice. Yes.

At 35 mph you'll need to blip your engine up to 4416 rpm for second gear. You'll need a bit more rpms to account for the drop in the time it takes to ease the clutch in. Do NOT pop the clutch in at this point; you do not want to disturb the balance of the car and break free the rear tires which are cornering hard at this point. You might want to perform this change down to 2nd a bit further back before you need to markedly tighten the radius as you turn into the final portion of this decreasing radius turn. I'd want to be securely in 2nd before turning into the final portion of this turn so I could concentrate on nailing my line and getting back onto the power as soon as possible.


Here's a case where the double clutch auto-manual gearboxes offer a significant advantage. A flick of the paddle by the driver and the computer+machinery executes a lightning fast change. That makes it too easy. I think they should be banned from professional motorsports!

It's SUPPOSED to be hard, dammit! :)


******************

"Motor racing is dangerous. It's made that way."

–Jacky Ickx (Six-time winner of the LeMans 24 Hours race, and former F1 driver)



******************

Is this on a race track?

If so, which corner of which track, and can you supply us with a URL for the track map as well as any videos?

I'll be honest and reply the obvious. No this ins't a track.

I practice on nights I'm off from work (around 1-4 am) on several highway ramps near me.

The areas I am using are sufficiently free of traffic so more than 90% of the time there are no other cars and I have yet to see a police car patrolling it.

Flame me if you want but I'm just trying to learn basic techniques. And from the replies it seems there is more debate about what the best driving line is than those worried about where this is occurring. I'm just trying to learn a bit more, not trying to cause a flame war or hurt anyone.

:iono:

haha, if it's a 1-lane off/on ramp then you have no "line"

just scrub the speed off naturally and call it a day

The proper way to take any interchange is as sideways as possible.

[ame="http://www.youtube.com/watch?v=8uW6iGxcNqQ"]Is this the worlds best drift? - YouTube[/ame]

You're welcome.

What BARN were you raised in?

Somewhere in here, I can't find a closer pic.

http://aieseclife.org/wp-content/upl..._wallpaper.jpg

My over long posts are based simply on the diagram and the lines given. While none are ideal, if I had to choose, I would choose blue everytime, without out a doubt and I'm confident I would win, by a lot.

Yes, essentially and only in the context of this picture and with the assumption that the exit of the corner is not immediately leading into another corner.

Of course. And clearly I'm making a specific assumption as recommending a full "track out" on exit.

In between the two orange dashes it's very close. Also, if you move the blue line over on entry you also widen it's radius not to mention moving the exit out. Then the real difference between the green and blue car at that point will be that the blue car will have a vastly superior entry with negligible difference on exit.

The green car would be traveling at a greater rate of speed due to preceding difference in radius.



Indeed!
I have a video of a bumper to bumper race between myself and another equal car at a track with a similar turn that followed by another turn (so no long straight) and the difference is clear. PM if that is of interest to you.
Indeed. So the blue car is going to arrive at the point of returning to throttle-exit much sooner so a gap will be created, a delta between the two cars. The exit speed difference between the two cars will be different (even though I argue by not much) so in order for the green car to close that gap, the straight following all this would need to be very long.
:thumbsup:

Let's make the assumption that the lap times between the two are identical and that this corner is followed by a long straight (allowing the green line to make up the gap created at entry).

If both are the same lap time what would you do? I would still choose blue as I feel it's safer, simpler and would be much easier to be consistent with. But that's me.


This has to be one of the more rewarding threads on this board. I was really looking forward to coming home from the track today and reading the responses.

:burnrubber:

And it was a complete thread hijack too!

To answer the op's question, since I didn't see if anyone actually did, just practice more. If you have a racing wheel and pedals with a clutch that's a great way to get used to heel and toeing and there are some really good sims out there e.g. iRacing, RFactor that can be pretty punishing if you're not perfect.

Yes.

This is just a theoretical corner, so it's hard to say, but I'm thinking the blue car might pick up a good 2-3 car lengths over the green car through the first portion of this corner. I wonder how much speed difference there would be as the green car begins to catch up at corner exit. In my mind this is a slow corner at the end, but the green car might have a 5+ mph advantage.

Maybe. It's imaginary, so who knows?

And if we imagine that a longish straight follows this … I wonder how long it would take the green car to make up the deficit? Would he? Hmm…

Heh. Now this is getting even more interesting, isn't it?

It's one thing to evaluate this in isolation, computing optimum speeds and time passing through this interesting corner only one time. But make it a race, and now other factors loom large.

Like you, Rice, my money is on the blue car.

Apart from my suspicion that this is simply going to be the quick way around the track, not just this turn in isolation, but the whole lap, the driver on that outside line has got his work cut out for him.

Under pressure, lap after lap, the green driver is going to find it more difficult to exploit the maximum from his tires and car through that corner. Not much margin for error in my imaginary corner, here. He would be far more likely to ease back a little for security (which would cost him dearly), and he'd be more likely (I'd guess) to make a mistake that would cost him even more.

Now, the blue driver can push the limits of his threshold braking and turn-in with greater security and with less likelihood of bobbling and make a right mess of it all. By COMPARISON, I'd say his job is far easier. By making fewer errors, he'd pull ahead just that much further as the laps mounted. His line allows pushing the limits with far more margin for error (lots of room on either side) and the car is flat and stable as he brakes down into the corner and changes down to his lowest gear shortly before doing his dirt-tracking, rallye turn around that sharp corner. It's not that it's easy, per se, it's just a lot less prone to time-robbing error than what the green driver faces, especially as he tries to change down while cornering hard.


Unless the green driver is a real pro, he's likely to become frustrated and flustered, yet again promoting the likelihood of mistakes. This would be especially so, if racing in close quarters.

Now, taking your scenario where they're turning equal lap times: Yes, but they're presumably "alone" out on the course when they qualified. With equal times, when it comes to the race this means they're likely to arrive at this imaginary turn of ours TOGETHER!

Uh oh.

Now things get much more interesting.

The green driver is likely to get distracted and flustered as the blue driver comes underneath him at corner entry (assuming the green is leading at this point). If green manages his line perfectly, and the subsequent straight is just long enough to make up the time lost on the approach, that'll put them neck-and-neck down that next straight, I reckon.


If blue is leading into this corner next lap, there's no room for green to get underneath him, not and have a hope of making the corner decently. Green will have to go around the outside, but that's not going to get a pass done on this corner, not with blue beating him down to the second segment.


And my NEXT question: Where's the FINISH LINE? Along this next straight? Down towards the end, maybe?

We've got a RACE! LOL! :)

My money's on Blue, but it could be exciting if green is an exceptional driver and is still there on the final lap.

By the way, Rice, I watched one of your race videos this past year and thoroughly enjoyed it. It was so exciting that I "sat beside" you for the whole race! And you took a great win! There are some beautiful segments to that circuit. I especially appreciated that downhill sweep through the woods with an interesting righhander at the bottom (iirc).

It even looks dangerous at some points. I like that. Modern motor racing circuits have been sanitized to the point that I no longer find most of them interesting



This imaginary corner has proven to be quite entertaining, hasn't it?


I have enjoyed this. :)

Thanks.

i dunno... i'd argue the opposite, the blue line requires perfect brake technique lap after lap, start braking 5 feet too late and you're gonna be overcooking the corner

at least the green line gives you more room and time to adjust things along the way

i dunno... as someone that does the greenline most of the time ***FOR Decreasing Radius Turns *** i find it easier to execute lap after lap... it's when i start experimenting with more aggressive attacks that require oversteer and greater rotation that i start to lose in terms of consistency..

Without knowing anything else about the corner and just taking the diagram at face value, that was my thought too. Especially with a car like the twins. The blue line looks more like an AWD turbocharged monster line. Seems the blue line car would make up some car lengths on entry but would be exiting lot slower - of course it depends on how long the exit straight is whether that would be faster or not.

Interesting points for both sides. Blue line is extremely aggressive and I hear what (s)he is saying about braking and turning.

I understand nothing here is to scale so hard to argue what is the most intensive points of braking and gassing and thus when you overload your tyres.

We really have to get a to scale map and car to do this... anyone want to meet up on a track? :D

I cannot say I know enough to argue convincingly one way or the other so until I've got an example, I won't add much more to this arguement that's useful.