Ideal line on specific course

[benkeszabo]

Hello!

I am a hobby driver from Hungary, and we have a new Go-kart course nearby, and i feel as i have reached my limits on the course.

I have a basic understanding about racing lines, but the course is quite tricky (to me), with several compound turns so i have trouble finding out which line to chose, most places i could argue about having a late apex , or go shorter instead to have a lower avg speed but much shorter line.

I did experiment quite some, but i don't seem to be making any more progress.

So i would like to ask any of you who feel up to it if you would be so kind and help me out with a closer to ideal (at least better than mine...) racing line for the specific course.

The course is ~4-500m long, and wide enough so you can overtake, and the Gokarts are 30hp electric ones with ~60km/h top speed.

Pink line is start/finish, and the course runs clockwise.

I am by no means a professional driver, and i realize that the ideal line might be up to discussion or choice at places, but i am open to try out different approaches too, or take any advice!

What i realized is: Since i am lighter than most who tried the track i am at a traction/braking disadvantage in and before turns, but i am faster due to the power to weight ratio in straights, as they don't put weight in the karts to bring us to tha same weight.
Also the course is quite new so traction i would say is similar on all parts of the line in all turns.

One more thing: there is a 4second "boost" button on the go-karts, which you can use once per lap and gives ~20% plus power , i would be interested in where you would chose to use it.

 

[itsid]

well, mathematically that's easy actually.. the biggest radius turns with the shortest overall tracklength is what you're aiming for,
that's the fastest way to get through the course,
since it allows the biggest possible speed at all times.

Now at one point or another you can swap a short course for a tighter radius turn or vice versa,
THAT depends on your engine, gearing and drivers ability...

Oh, and if there are inclinations or declinations in the course it all again shifts slightly towards a declination and away from an inclination of the track.

Being lighter is no disadvantage at all..
even if you slide through a corner you'll have less outward momentum and can keep a greater speed without loosing control.

Where to use the boost.. again very simple to answre.. where you get the most advantage from it (right after the slowest turn and onwards to the longest straight)
ideally.. looking at the track that again will be up to you, but personally I'd choose the smaller of the S-curves towards the final corner,
that looks like it'd be a relatively slow turn followed by the best straight you can get.

'sid

 

[Badot]

It really, really depends on what kind of power to weight ratio you have on the karts. Generally a good place to start for me is lining up each corner before a straight so you can maximize exit speeds, then work backwards until all your corners connect. Knowing your max exit speed and where you have to start accelerating to attain that will do a good job at dictating your lines.

Just off the top of my head, here's my very loose suggestion... fair warning, it's a crappy mspaint line. At the very least shorten the U's where you can since some of them extend way further out than necessary... but you can kind of see where a proper line can turn a bunch of little curves into one wide, smooth motion -- you want that wide, smooth motion to start before the end of the curves leading up to a straight so you carry the most speed in possible into the straights.

Scrubbing off a little extra speed in the short distance leading up to a turn can be more than worth it to gain a little bit of exit speed which will be carried over a nice long straight.

 

[benkeszabo]

Thats what i was looking for!

Well i don't know how these karts compare to other karts,
But as i said they are ~30hp electric ones with an approximate weight of ~170kg and me being ~70kg.
It comes to 8kg/hp or 0,125 hp/kg.
But i realize that doesnt say much. Especially about the powerband.

They limit the torque of the karts though in the lower rpms so they are similar to petrol engine ones in the sense that grip going in to turns is much more of an issue than coming out of them...
The tyres don't seem to lose traction at all when accelerating out of turns so a straight exit is (i guess?!) not that much of goal this way. Am i wrong with this?

Add to this that the rear axles are indepentent with one electric motor powering one wheel, and the disc brake is attached between the tyre and the motor.
This way the inner wheels tend to lock up under any trailbraking worth to mention due to the weight shift and the independent axles. Also the tyres are 1,5 bar front and 1,8bar in the rear, so it makes it oversteer when trailbraking
I tried leaning in when trail braking to oppose this, but i am thinking that braking while still straight but harder and shorter and then turning in might be a better approach due to the setup.

So i have the feeling that the entry part of the turn is harder to execute well than the exit with this setup.

Do you think it still pays to focus on a late apex like you said with the karts set up like this ?
This is also what i gathered from reading up some on the subject, but the setup got me thinking.

Thank you for your input!

 

[Badot]

The tyres don't seem to lose traction at all when accelerating out of turns so a straight exit is (i guess?!) not that much of goal this way. Am i wrong with this?

Depends on the vehicle again. Imagine starting from zero and flooring the kart while you're turning as hard as you can before you lose traction. Conceptually it'll be some kind of spiral. If you graph the spiral to scale and have a picture of the track on the same scale you can overlay it to see the best line to carry speed into the straight. And if you graph your speed on the spiral you can get reasonable estimates on your ideal entry and exit speed as well.

Just remember to always use clip points on the inside. It's very, very rare for it to not be effective doing that but a lot of people get so obsessed with exit speed they add a ton of distance on the higher angle turns.

 

[J_Walker]

I normally race motorcycles and things with two wheels.. so that's what I'm basing this off of. and its subject to change as I look at it more and study more into the track itself.

and of course I normally like to use the track and try out my ideals of what works best for my style of riding...