[Spridgets] Help - Seemingly Incurable Brake Fade

[Larry Daniels]

Jim, your formulas are right and your math is not flawed, so your error must 
be in your assumption of 10 second lap times.  I assume you pulled that out 
of the air?

There are very few street cars on street tires that can crack 1G.  A 40 or 
50 year old Spridget won't even come close.

LAD

--------------------------------------------------
From: "Jim Johnson" <bmwwxman at gmail.com>
Sent: Monday, October 05, 2009 1:58 PM
Cc: <spridgets at autox.team.net>
Subject: Re: [Spridgets] Help - Seemingly Incurable Brake Fade

Daniel,

Just using the math here....  Where am I going wrong....

Quote from

http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=704

**Lateral g-force = 1.22 * radius of track / (lap time * lap time)

Make sure radius is in feet, and time is in seconds. The number you are left
with is your maximum lateral g-force.**

Given a corner radius of 100 feet with, say, 10 seconds around the corner -
I get:

G = 1.22*100/(10*10)  =  1.2 Gs

Ergo, 1.5 Gs is not an unreasonable value.

Now... I admit I haven't actually timed a Spridget around a 100 foot radius
circle so I don't know if that time is reasonable or not.  10 seconds might
be too short a lap time. If so, lateral G would go under 1.   However...
it seems at least mathematically reasonable.

Such a circle has a circumference of C = pie*D = 3.14*200' = 628 ft.
Navigating that distance in 10 seconds we get 62.8 ft / sec which comes to
42.8 mph.  Is that possible?  I don't know but I'm willing to bet Frank
could do it in the Speedwell Sprite   ;-)

Anyway, its an interesting engineering problem.  I also suspect that
instantaneous lateral G force during the lap might vary significantly. There
may actually be times when the vehicle experiences an instantaneous lateral
G somewhat higher and somewhat lower??

Cheers!!
Jim

On Mon, Oct 5, 2009 at 9:47 AM, <WeslakeMonza1330 at aol.com> wrote:

>  I don't think you'll reach that higher a lateral load on road tyres in a
> Spridget.  Front wheels with no traction (locked or wheel spinning) go
> straight ahead while rear wheels with no traction (locked or wheel
spinning)
> will want to lead and the car will commence a spin.
>
>
> In a message dated 05/10/2009 02:05:09 GMT Daylight Time,
> bmwwxman at gmail.com writes:
>
> with a lateral g load of about 1.5 G
>
>
>



--
Cheers!!
Jim
Only two things are infinite, the universe and human stupidity, and I am
not
sure about the former. - Albert Einstein
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