smart51
|
| posted on 4/7/07 at 02:38 PM |
|
|
cornering speed
If a car will turn a 20m radius corner at 35 MPH at the limit of grip, will it do a 40m radius turn at 70 MPH, a 60m radius at 105 and an 80m radius
at 140?
If it doesn't work like that, how does it work?
There is an island near me with a 20m radius and my car will do 35 MPH round it with the tyres just starting to squeal. Cadwell Park's longest
straight is more than enough for my car to reach its rev limited top speed of 120 MPH. The next few corners are not less than 70m radius. If I had
the nerve, the car would in theory not have to slow down until the corners in the "centre" of the circuit.
|
|
|
|
|
mookaloid
|
| posted on 4/7/07 at 02:44 PM |
|
|
I've no idea if it really is a linear relationship as you suggest but I would be interested to know. I guess you can either work it out
mathematically or do it by trial and error
"That thing you're thinking - it wont be that."
|
|
|
worX
|
| posted on 4/7/07 at 02:48 PM |
|
|
Would things like heat generated, in/on the tyres, at certain speeds affect the linear aspects of it?
That and the track should (in theory) be a lot better surfaced, and therefore allow the trial and error aspects to be tested with a bit more
confidence!
Steve
[Edited on 4/7/07 by worX]
|
|
|
JoelP
|
| posted on 4/7/07 at 02:52 PM |
|
|
I would guess that maximum lateral g is constant, and that you could work out from the g force how many degrees you could turn per second at a certain
speed. Ie faster you go the lower the degrees per second.
|
|
|
matt_claydon
|
| posted on 4/7/07 at 02:57 PM |
|
|
Lateral acceleration (g) generated when going round a constant radius bend is equal to the speed squared divided by the radius:
a = v^2 / r
therefore in order to double the speed you would need to quadruple the radius. This is theory or course, other factors will almost certainly play a
part in the real world.
|
|
|
smart51
|
| posted on 4/7/07 at 03:15 PM |
|
|
quote:
Originally posted by matt_claydon
Lateral acceleration (g) generated when going round a constant radius bend is equal to the speed squared divided by the radius:
a = v^2 / r
therefore in order to double the speed you would need to quadruple the radius. This is theory or course, other factors will almost certainly play a
part in the real world.
That seems more like it. That puts the big radius corners at cadwell more like 80 and 90 MPH. The start - finish straight is then more like 115 MPH
before braking into coppice.
|
|
|
zetec7
|
| posted on 4/7/07 at 06:56 PM |
|
|
It's all based on what is known as "Critical Curve Speed", and is a function of several things, including coefficient of friction of
the surface, radius of the turn, elevation & superelevation, etc. to calculate the maximum possible speed for a specific line through a specific
turn. As a Collision Analyst & Reconstructionist, I used to work these things out all the time, but I never bothered to work out whether there
was a linear relationship. I suspect it is roughly linear, though....
http://www.freewebs.com/zetec7/
|
|
|
Maradona
|
| posted on 4/7/07 at 07:08 PM |
|
|
You need to adjust your akerman diagram, the akerman is the arm that conects the weel to the direction, making small corrections in the arm angle you
can improve your cornering speed, if you want more information I can send to you,
I hope you can understand my english
cheers
|
|
|
ChrisGamlin
|
| posted on 4/7/07 at 08:07 PM |
|
|
You won't get round them flat out, trust me
I was there last week in my Locost R1, I was hitting about 120mph in 6th along the bottom straight, Coppice once you have the confidence / tyre heat
(on Yoko A048s) is 6th gear, half a lift before turning-in at about 115mph and apex at just under 110mph, the next corner is down one gear at about
90mph then the last one before Park straight is down another into 4th at about 75mph.
Youtube vid of a very rare clear lap
[Edited on 4/7/07 by ChrisGamlin]
|
|
|
smart51
|
| posted on 4/7/07 at 10:00 PM |
|
|
quote:
Originally posted by ChrisGamlin
You won't get round them flat out, trust me
That's what I thought, hence the question. If I can do a 20m corner at 35 and the speed goes up with the square root of radius then coppice is
an 85 MPH corner. It isn't steady state though so I should be able to carry more speed in. "Turn in at 115 MPH"
|
|
|
ChrisGamlin
|
| posted on 5/7/07 at 07:45 AM |
|
|
You should try Blancimont at Spa, from what I remember of it last time I went, thats turn in flat out in a BEC at about 125mph, makes you double check
your wheel nuts before going out
To be honest you could probably build up to doing Coppice flat as well as you can see on the speedo that Im only dropping ~5mph with the lift and the
uphill nature of the corner naturally scrubs off more speed than you anticipate, but I don't have a cage and it was only a trackday so not worth
risking too much especially as the grass was still wet! I was quite pleased with how quick that "lap" was though albeit timed from an odd
starting point due to lack of proper clear laps, looking at the timing sheets from the RGB race there this weekend just gone, it would have put me
about 7th or 8th fastest in the race albeit still 2-3 seconds slower than the fastest class C (blade) cars.
[Edited on 5/7/07 by ChrisGamlin]
|
|
|
