Decreasing radius corners

[Frost]

Originally Posted by 7thgear

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.

[Tgionet]

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

[rice_classic]

Originally Posted by 7thgear

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.

Originally Posted by Frost

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

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.

Originally Posted by 7thgear

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

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.





I love racing.

[7thgear]

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.

[rice_classic]

Originally Posted by 7thgear

yes and no..

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



:loading:

[rice_classic]

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

Some elaboration on why I like the blue line.





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.

[7thgear]

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?

[comic0guy]

Originally Posted by rice_classic

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

Some elaboration on why I like the blue line.





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.

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.

[7thgear]

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.

[serialk11r]

Originally Posted by rice_classic

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.
..
Thank your putting up with me.

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.

[Tgionet]

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.

[Porsche]

Originally Posted by rice_classic

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

Some elaboration on why I like the blue line.





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.

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.

[Porsche]

Originally Posted by ZionsWrath

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?

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!


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

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



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[Porsche]

Originally Posted by ZionsWrath

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.

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?