2 cents from a British lurker.
I agree (not having ever tried rear steer mind you) that it's all probably
more about what you're used to. You would probably find it impossible to
control a boat with front steer until you completely relearnt how to handle
it. In my offroad racing days, one of our club members built a Landrover
for fun events which had reversed steering (clockwise on the steering wheel
turned left) - he got so used to it that one day he drove his road going
Landrover into a parked car; when asked what he was doing he just said "I
just forgot I wasn't driving that other bloody thing".
The other aspect is that all the collected experience is with front steer,
if you have to go rear steer because you can no longer make front steer
work, then as they say, you're on your own. You need to accumulate 100
years of automotive development of what started out as a horse drawn
carriage with a rigid centre pivot (true "king pin") axle into the modern
zero scrub, castored, camber neutral ifs, but do it on your own on the back
end.
And for a sight of a trial rear steer testbed, try:
http://www.mira.co.uk/fluids/ftcsssc.htm
Jon Hobden
-----Original Message-----
Date: Thu, 25 May 2000 16:21:14
To: land-speed@auox.team.net
From: "Lawrence E. & Cathy R. Mayfield" <lemay@hiwaay.net>
Subject: Front and Rear Steering Thoughts...
Wow, what an interesting thread! I sat down a few moments ago to think
about all that I had read on the thread and to see if what I had read I
understood. First, there were many thoughts about why do a rear steer if it
is not needed? What are the benefits. Well I assumed that rear steer was
being used (thought about) because the wheels in front are pulling the car
instead of pushing it. Being able to steer from the rear wheels would seem
to reduce the complexity at the front by reducing the steering knuckle set
ups, CV joints or u joints, etc. Putting the steering at the back wheels
seems so logical in this case because we would then just be running the car
backwards so to speak. And we all have had some sort of experience in
backing up..most of the time we make mistakes (you ought to see my driveway
- - car tracks over the lawn on both sides). I attribute this to looking
over
my shoulder while going backwards. But in a purpose designed car I would
hope to be facing forward! So what is it that makes this so difficult.
There was some thoughts about the facts that the drive wheels arrive at the
corner first and we have to think ahead to make it work right. For sure!
However, I don't think this is the reason straight line cars experience
difficulty.
Danger Warning Will Robinson...read at your own peril....outlandish
thoughts from here on...
Ok, now that the disclaimer is out of the way, here is what I think. We
all grew up being taught that in a skid we need to turn the front whel into
the skid to regain contro. And why is that, well after drawing a small free
body diagram, I see that when the front steering wheels are turned in the
direction of skid the rear drive wheels tend to drive the car into that
direction giving directional control back to the driver. Thia is all pretty
straight forward.
Now what happens when a front drive rear steer goes into a skid. Our
training says to turn into the skid. Right? So if we turn into the skid,
the drive wheels pull the car even farther off into the skid. This most
obviously causes consternation and a lot of over correction. The truth is,
that in a rear steer car the steering wheels must be turned away from the
skid not into it. That way the drive wheels will pull the rear of the car
around and back into directional control.
One list member correctly, I believe, hit the nail on the head. It is all
what we grew up with. Had we been driving rear steer all along, we would be
having this discussion about front steer! I think that a well designed car
with the driver brainwashed into the correct manuevers to get out of spins
and skids would fare just as well as any other car.
Would there be any interest into building a small go kart size test
vehicle? Heck even a go hart would work. Just need to put the driver and
control in so that the driver faces the "front" drive wheels and rig the
steering. The get out on the skid pad with some wet skids and see how to
control? Heck, maybe this is my "barstool" pit machine...
Control is now returned to the reader.
mayf (with migraine so thoughts may be fuzzy)
L.E. Mayfield
124 Maximillion Drive
Madison, Al. 35758-8171
ph: 1-256-837-1051
http://home.hiwaay.net/~lemay
lemay@hiwaay.net
Sunbeam Tiger, B9471136
Sunbeam Alpine Bonneville Land Speed Racer,
'66 Hydroplane Drag Boat (390 FE)
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