Hairpin turn in low hp kart

I doubt it on the overheating. We ran 15 lap races. The tires came in around lap 3 and stayed. I definitely overdrove compared to the faster kid and I did not feel like tires ever got too hot. Also, maybe because it’s summer but they start decent too. They come in fully a bit better though.

Maybe if you drew your line so that it represented the centerline of the kart, you might get a better understanding. Your kart is approximately 40 inches wide and your line is right up against the apex of both the left turns and right turns. Also going in and coming out.

That could help, did not think about the kart width to be honest. I will see if it makes difference, it should however.

The interest in rental karts has caught me by surprise. I know they’re out there, but the enthusiasm I see here is not something I anticipated. Great to see so many people interested in karting. Long before I became interested in IKF karting, I did drive a kart at a rental track and had a ball. After I opened my shop, I did some work for a rental track in San Jose California. We actually had a couple of club races there.

@alvinnunley Some day I hope you crack open the treasure trove of your karting pictures (memorabilia like old race posters etc would be cool too) from the 60-70s if ya got any.

My collection of pictures is trivial compared to Rod van Deusen. You can contact him on Facebook. Would love to see him here. Right now he’s working on restoring one of my original “Mayko shark” karts that I built in the mid-seventies. I contributed a reproduction of the 1st fuel tank I built for that kart. It was fabricated and welded by Tab Bell who worked for me when I was building tanks. He welded most of them.

To Alvin’s point about considering you kart’s width; you are driving 4 contact patches (maybe 3 on corner entry with a kart), and not just a point at the center of mass for your kart, so I have always found it more helpful to think of driving a trajectory instead of just a ‘line’. By trajectory, I mean the combination of the line your kart’s center of mass is traveling, overlaid with the slip-angle generated orientation of your rectangular (or triangular) contact patch relative to the ‘line’.

For example, unless you are using some kind of scandinavian flick to ‘back’ the kart into the turn, then from when you initiate the turn, to the 'rotation point in the turn, you will typically be on an understeering trajectory (a vector drawn from the back to front through your kart’s ‘rectangle’ would point to the outside of the line your driving - away from the turn’s apex). When you reach the turn’s rotation/apex point, the vector would be more or less tangent with the line your driving. And when you starting accelerating out of the turn your trajectory would typically morph into a more oversteer orientation (the vector pointing to the inside of your line… towards the turn.

That said, what creates the trajectory is the slip angle of the tires, so it is real, but very subtle (on the order of a few to maybe 10 degrees). When you think this way, and you understand with your kart/tires need, then it makes it easier to work out what driving ‘edits’ you need to make to produce the tire loads that will generate the slip angle levels you want at specific locations in each turn.

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Thanks Al. I hope to see the kart he’s restoring.

@Stacker this combines with what TJ was saying. About pre rotating. I think.

Interesting. The width of kart affects radius. Never thought of it like that.

Yes, there is a lot of people like me who are less experienced but are trying to improve and to stand out from others, maybe someone offers you a seat in some competition if you win something. The thing is, a lot of people don´t have money for competitive karting, like me, so they just go rental. You don´t know how happy would I be to drive some stronger kart, it doesn´t matter which, just some stronger, competitive kart and to have someone to teach me the techniques on the track. But unfortunately motorsport is not so developed here and there is almost no chance for anyone to go from rental to competitive unless you don´t have loads of money. So yeah, we, rental drivers, take it pretty seriously :grin:

@speedcraft Yeah, I understand what you mean, but I often find it very difficult to even draw a regular line or even imagine it. I haven´t found a program that is made for something similar yet. That is what I wanted to ask Al.

@alvinnunley What is the program used for that blue picture?

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I know that feeling. For years, I raced rentals and I was super serious about it. When I won my first rental championship, I screamed in my helmet.

Pavle, I was not clear… I did not mean draw your trajectory, I mean FEEL it when you are driving… it is happening if you are generating any reasonable amount of slip angle. So, try to recognize the influence slip angles are having on the line you are trying to drive, and how it changes throughout a turn. Once you can feel it, then you can surgically adjust your driving inputs to produce the trajectory/line you want. :+1:

Surfcam, very expensive, professional CAD/CAM software. I used it daily to program very expensive vertical milling machines. 2-D, 3-D, 3-D surfaces. Lots of fun.

Pavle, do you understand slip angles yet?

I understood that, but I accidentally connected that to drawing for no reason. I am aware how it affects the line but I will try to take it more seriously, so far I knew that it affects it but I was simply correcting that off-line trajectory by sharp inputs before next direction change to get back on the course, if it happens to affect my line too much.

Yeah, I do. Should be the angle off the racing line (negative) produced by understeer (oversteer in the shape of drift I guess) if I am using the correct terms (probably not, my English is not good enough for anything but understanding others and simple communication lol). It affects your line and you need to include that when you are trying to make the corner. I understood that the first time I went to my track, look at this:

This was the thing I felt the first time I was driving here, going in too fast, and you understeer to the side, instead to the perfect line. Now tell me, did I mess this up, is this accurate at all? (rough understanding of slip angle). Because the more I think I know what it is, the less I trust my logic…

Your English is far better than my Serbian. Which is zero. I am always blown away by how everyone else in the world speaks at least two languages well, it seems.

In any case yes I think you understand. If we think of Al’s boxes along the line, it can be visualized. Where they are pointing relative to where they were and are going. I think.

I think it’s rotation principally. But yeah under and oversteer influence the karts direction relative to line. But that’s more as it (the turn) evolves or after the fact.