Track Tac

An engineering question about how forces relate to setup

paulkish

paulkish

old fart
I'm using the RF as the reference in this question. All numbers are hypothetical.

The kart is on the scales and the weight of the RF reads 100#'s.

When you turn the wheel left 10 degrees, weight on the RF changes 10%. <change per post #4, put in here]

Next is the question part and I'm going to first put in my assumptions, to make it easy to pick the question apart and I'll learn from it.

I'm assuming a kart setup having the numbers I made up is put on the track. On the track when the wheel is turned 10 degrees in a turn, I assume lateral weight or g's will occur not only because of speed, but also because of the sharpness of the turn. I also assume because of the 10% increase in weight which occurs on the scales, additional weight will be applied to the RF, because of the mechanical setup on the scales.

I assume the above paragraph is correct and if not hopefully someone who knows those things will correct what is wrong.

Next comes the lead in questions to my real question, which will follow. Is the creation of lateral weight or g's out on the track, proportional to an increase in speed? Is the creation of lateral weight or g's out on the track, proportional to an increase in the sharpness of the turn.

The question: Does the percentage of increase in weight out on the track at the RF because of mechanically turning the wheel proportionally increase, with an increase in speed or the sharpness of a turn?

edit: ... :) and if not why?
 
on a kart generally the weight on the rf is going to lower with left wheel input. this is primarily due to caster angle and a positive scrub radius on the front end geometry. the result though is not necessarily the identical situation on the track though. you have essentially lowered cross which allows weight to come off the lr and free up the back end as the weight travels right and forward upon corner entry. not going to try to go any further than that with an explanation but that is the basic concept.
 
thanks

Then when you turn the wheel to the left on the scales weight decreases, it does not increase. Is that correct and if it is I wrote, "When you turn the wheel left 10 degrees, weight on the RF increases 10% to 110#'s.", is not correct.

I'll fix it in the question, later.

But I still figure, probably also incorrectly, that out on the track a change will occur per what happens on the scales at the RF. Am I figuring correctly?

Will an additional decrease on the scales, cause an increase out on the track. I don't think it matters if on the scales there is an increase or decrease, will it be a proportional increase or decrease out on the track?

... i'll just leave my question wrong, because it's just a lead into wondering about if what you do on the scales directly relates proportionally to what happens on the track, as far as a weight change at the RF.

edit: It's a tough question to write and ask so it's understood. I hope this post is getting closer to the question.
 
ya know... after spending the time writing the question, I don't really care about the answer. I think it's a who cares sort of subject and question.

i'll leave it though, just to aggravate those who really know stuff. ... :)
 
The weight will transfer to the right front when the situation turns dynamic. Years ago i had built a spread sheet to put all of the numbers in to estimate weight transfer. Now this is back with the Banshees and wanting to unload the LR to free up thru the turns. I was able to delve deeper into the Whys of the setup. Basically set the steering at the angle i turned on track, wrote down those numbers and plugged into the spread sheet.

Now, the answers obtained from this was a better understand why there was a performance "hole" in regards to cross, (52 good 54 bad 56 good type of thing) The other thing that became clear is the different phases of the turn, and how to adjust for those segments of the turn...

Basically i found that i could get away with a half inch of rear stagger with 55% or so cross as long as i could get the kart passed the first segment of the turn and unload the LR late enough to just entering the steady state phase 2 part of the turn without needing to turn to the left from the center off, and not need turn to the right as well.

Middle off moving the CoG made the most difference, without effecting the entry as much.

Now, this is 2000 2002 era, preps a whole lot bigger part of the game now, but the physics still the same when the CoF rises...

The dynamics can be a fun yet frustrating rabbit hole to look into...
 
Your turn on the scale is in static condition.

The turn in on the track is dynamic.

The speed of the vehicle being turned, adds weight to the rf, because the time and distance are parts of the equation not relevant in the static
condition.
 
PD Power said:
Your turn on the scale is in static condition.

The turn in on the track is dynamic.

The speed of the vehicle being turned, adds weight to the rf, because the time and distance are parts of the equation not relevant in the static
condition.
Click to expand...

All true, but it is data that can help with understanding the effects of a known caster at a known amount of steering input... am I correct?
 
racer47 said:
All true, but it is data that can help with understanding the effects of a known caster at a known amount of steering input... am I correct?
Click to expand...
Yes, this can be figured, However it is an extremely lenghty equation, need a good sized blackboard to teach it on.:)
Of course, a problem arises to finding a fixed answer, when we consider the effects of an uneven track surface, plus the angle of the track itself, also known as banking. Of course the line the kart rolls on will have ever changing banking....unless the track bank is symetrical and the kart runs a line
perpendicular to the center of the radius of the turn.
Caster, camber, kpi and scrub radaii must be figured in.....plus the ever changing toe angle, and the ever changing centerline as the vehicle is steered.
What is highly desireable is to find the "setup" which allows you to come off the apex with the most power
possible being applied, short of collapse of friction, tire to surface.
It's as much art as science.
 
Thank you very much Barry.

ya wana hear something scary Barry? ... :)

I think I understood all of what you wrote, it makes total sense to me, it all fits into my thinking like a glove on OJ's hand and it was a pleasure to read.

thanks for the reply

paul
 
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