Howdy
Both a boat and an airplane are operating on or rather in, a fluid
medium, as opposed to a LSR vehicle operating on a hard surface. Convention
is one answer I would have as to why all vehicles are FWS, "Its' always
been done this way". As Land Speed racers, we innovate continuously, the
concept of RWS is only one of a multitude of ideas that are being
investigated and used on the Salt.
At 11:19 AM 6/7/00 , you wrote:
>These thoughts are definitely intrigueing, and
>certainly border on the "mysterious". If front
>wheel steering is generally accepted as best, why
>haven't boats rudders been moved to the bow? If
>the boat's rear steering is best, then all of our
>questions about "Why haven't teh sterring wheels
>been moved to the back?" are quite valid. Having
>raced both, it does seem to me as though the rear
>steering on a boat is slower than the front
>steering on a car, and thus should be better for
>a land speed car, but....?
>
>Dick J
>
>
>--- john robinson <john@engr.wisc.edu> wrote:
> > Howdy,
> > I think the main difference in a Rear
> > Wheel Steer vehicle while
> > doing course corrections, is the lack of
> > perceived motion in the desired
> > direction; because the rear of the vehicle is
> > going in the opposite
> > direction (vehicle tail goes left while the
> > driver wants the direction of
> > the vehicle to be going right), which is
> > opposite to the "normal" driving
> > feel. The comment of driving to a correction
> > indicator is not bad, a long
> > painted line on the hood in conjunction with a
> > pressure probe attached to
> > the nose which would effectively lengthen the
> > nose of the vehicle, giving
> > the driver a long pointer to view the actual
> > direction of the vehicle,
> > especially if the driver is as far back in the
> > vehicle as possible. I
> > believe a RWS vehicle comes down to driver
> > adaptability/skill, more than
> > the dynamics of FWS vs. RWS..
> >
> > (the rear wheels skid to the outside of the
> > turn in a "normal" Front Wheel
> > Steer) while in a RWS
> >
> > At 09:55 AM 6/7/00 , you wrote:
> >
> > >A picture is worth a thousand.......
> > >
> > >Having thought about this some more, Jon,
> > you're right about kid's toys and
> > >what you are brought up on, as I said a few
> > days ago, boats (and for that
> > >matter most aeroplanes) manage by steering
> > from the wrong end.
> > >
> > >The problem with rear steer is that it
> > requires anticipation (and a blind
> > >faith in the future) on the part of the
> > driver. Consider a car off the
> > >desired centre line, within the limitations of
> > the character set (you'll
> > >need to select a monospaced font for this like
> > Courier or Lucida):
> > >
> > >(For the example we'll assume a simple reverse
> > tricycle for the rear steer,
> > >I can't cope with trying to get offset rears
> > to look right)
> > >You start a fair way offline, and turn towards
> > the line:
> > >
> > > | |
> > > | |
> > > +-------+ | +-------+ |
> > > | / / | | | | | | |
> > > | | | | | |
> > > | | | | | |
> > > | | | | | |
> > > | | | | | |
> > > | | | | | |
> > > | | | | | | \ | |
> > > +-------+ | +-------+ |
> > > | |
> > > | |
> > >
> > >
> > >Once heading back towards the line you
> > straighten up
> > >
> > > / | / |
> > > / / | / / |
> > > / / / | / / / |
> > > / / | / / |
> > > / / | / / |
> > > / / | / / |
> > > / / | / / |
> > > / / / | / / / |
> > > / / | / |
> > > / | / |
> > >
> > >
> > >This is where it gets to be different.
> > >With a front steer you basically get to the
> > line and point the wheels down
> > >it (obviously there's a progression, but you
> > get the idea).
> > >With rear steer, you need to correct BEFORE
> > you are aligned (like turning
> > >the back of a boat in against the dock).
> > >
> > > | |
> > > | |
> > > / | / |
> > > / | / / |
> > > / | / / / /
> > > / / / /|
> > > / / / / |
> > > / / / / |
> > > / / / / |
> > > / / /| / - / |
> > > / / | / |
> > > / | / |
> > > | |
> > > | |
> > >(sorry about the "-" for the rear wheel, but
> > there's nothing between that
> > >and "/" in the character set - I'm sure you
> > get the idea)
> > >
> > >
> > >Once you're back online, everything's hunky
> > dory:
> > >
> > > | |
> > > | |
> > > +-------+ +-------+
> > > | | | | | | | |
> > > | | | |
> > > | | | |
> > > | | | |
> > > | | | |
> > > | | | |
> > > | | | | | | |
> > > +-------+ +-------+
> > > | |
> > > | |
> > >
> > >
> > >Except that you have to effectively anticipate
> > the correction to each minor
> > >deviation in the same way. I'm sure you
> > could condition yourself to it,
> > >but at the end of the day is it worth learning
> > a whole new driving style?
> > > It's also worth noting that neither boats
> > or planes are so concerned
> > >about accurately following a line; they
> > concern themselves only with the
> > >next waypoint, so maybe in today's non-SA GPS
> > era the solution is in
> > >driving to a correction indicator rather than
> > what you see out of the
> > >window.
> > >
> > >It's all very well my saying all this - the
> > likelihood of ever having to
> > >prove it is zero. Good luck to any of you
> > guys who have the ability,
> > >money and commitment to actually try any of
> > this out.
> > >
> > >
> > >Jon Hobden
> > >Horley, England
> >
> >
> > 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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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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