XPost: alt.comp.os.windows-11, misc.phone.mobile.iphone
On 2025-05-28 13:52, Tyrone wrote:
On May 28, 2025 at 4:15:44 PM EDT, "Alan" <[email protected]> wrote:
On 2025-05-28 03:52, Carlos E. R. wrote:
Or like the "fact" that racing cars go around corners on a catenary
curve?
Oh, he said that too? 😂
Yup.
He declared that I couldn't possibly race cars or teach racing, because
HE claimed that everyone "knows" that cars going through a corner do so
on a trajectory that's a catenary curve.
I scoured the net, and the ONLY reference to a "catenary" in relation to
racing "cars" was a set of plans for the race track used for racing
model cars made out of wood.
Wow. I have never heard this term before, but CLEARLY auto race track curves are NOT catenary curves. They are banked curves. For obvious reasons.
The discussion was around the trajectory a road racing car takes around
a corner. Not the physical shape of the track.
Without delving into the subtleties, it's fairly easy to see that at the
most basic level...
(and let's use a 90° corner as the example)
...the driver of a car attempting to got through a corner with the
greatest speed should start on the outside edge of the track (i.e. on
the left side for a right-hand curve), take an arc that clips the inside
edge in the middle of the turn, and then that same arc will carry you
back to the outside as you exit the corner.
That 90° arc will have the largest radius, and so will result in the
greatest speed around the corner for a given amount of grip and hence
lateral acceleration.
But then there are the subtleties to be considered, aren't there?
By taking that, basic, circular outside-inside-outside arc you are at
maximum lateral g-force from the moment you being turning until the
moment you complete turning. And from the "friction circle" that this
means the tires cannot be producing any force linearly for all that time.
So it is well understood that it pays to modify that basic line so that
the radius opens up as the car gets (roughly) halfway through the corner...
...so that you can being applying linear acceleration sooner.
After all, the race isn't over at corner exit, so getting to that point
first isn't the goal.
Typically, a corner on a road racing track is followed by a straight. So
the goal becomes to navigate the corner in such a was that you minimize
the time, not to the exit of the corner itself...
...but rather to the point at which you begin braking for the NEXT corner.
At that's why the debate began: what is the line that a car takes to
minimize that total time.
Arlen read once... ...somewhere... ...that that line should be a
catenary curve.
I have read extensively on the subject of racing since I was about 10
years old. I've read books on racing physics, and books by racing
drivers, as well as books by a famously successful driving coach.
I've also talked with many experienced racers since this idea of a
catenary curve being correct came up...
...and not ONE of them ever heard of it.
I finally found ONE reference to the use of a catenary curve in car
racing...
...wooden model cars.
The official track design for wooden "Pinewood Derby" gravity racing
uses a catenary segment of track to transition from the sloped section
to the horizontal one.
That's it.
--- SoupGate-Win32 v1.05
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