Howdy,
There are cars out there that are being driven, actually RACED in
reverse, several circle tracks are holding reverse races, with the cars
being driven backwards at up to 90 MPH!!! the steering has been modified to
positive caster (if the car went forwards, it would be negative) and
looking over their shoulders!!!!! while dodging the other cars, and going
around in circles......
Here at the University of Wisconsin Mechanical Engineering, the
students built a streamliner (sort of) about 15 years ago, using a
chainsaw motor for propulsion, with rear steer, about 15 feet of wheelbase.
one of the design parameters was to gymkhana the vehicle, but a high center
of balance coupled with the long wheelbase, gave the driver a real tippy
ride and it never reached any actual competition.
Your thoughts of skid steering are right on! the steering is
reversed in this respect, and coupled with many miles of "regular"
steering, this will cause driver error.
thanks for your input...
At 11:33 AM 5/25/00 , you wrote:
> 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)
John Robinson, Mechanician
Mechanical Engineering University of Wisconsin
1513 University Ave.
Madison, Wi. 53706
608-262-3606
FAX 608-265-2316
Current World Land Speed Record Holder
Bonneville Salt Flats
H/GCC 92 cu.in. 1980 Dodge Colt
131.333 MPH set 1995
136.666 MPH set 1996
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