John:
what I meant to convey is that the most perfect suspension I could imagine
might give 80% contact. I was using a very low unsprung weight, a very high
sprung weight, and Newton's Second Law. (With damping always imperfect, I
have no idea how close we could get to that suspension response.)
And don't forget that was at very high speed (400mph, I think) and a "dip"
that I now believe was an unusually bad one.
Russ, #1226B
-----Original Message-----
From: owner-land-speed@autox.team.net
[mailto:owner-land-speed@autox.team.net]On Behalf Of John Goodman
Sent: Thursday, October 16, 2003 11:07 PM
To: land-speed@autox.team.net
Subject: Re: Suspension Design and Test
Keith uses a straight axle rear so camber curves will
not change. From the simulators perspective, the
single most important feature will be roll center. I
can simulate pitch, roll and squat so changes in RC
will be interesting. I can't remember what Keith has
for front suspension but whatever it is, same thing
applies as with the rear. Keeping unsprung weight to a
minimum is important. It just helps the dampers react
quicker and keeps them in control. Sprung weight
should be kept suitably in check with correct spring
rate and damper valving. Minimal lateral movement in
RC (less than 1"), assuming RC is not too high
(anything above 3" is too high IMHO), should help with
straight line stability. Of course, static front
camber (1/4 degree negative won't hurt) and as much
caster as you can tolerate helps a bunch. Don't
overlook the value of proper damper valving. Russ has
shared with us that we can achieve 80% tire contact
with a suspended chassis. Correct damping can help
increase that % of contact.
What WinGeo3 can't do is determine optimal spring rate
or dampening. I have passed on to Keith my
inclinations here (I like to start at a spring rate at
or slightly higher than corner weight). Control of
ride height will determine this. Dampening would
likely be valved for low speed spring oscillations of
around 100 MHz or less. From what I remember,
Bonneville hands a driver mostly periodic bumps.
I will be out of town until Tuesday of next week so
Keith, I will contact you then.
John Goodman
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