Howdy,
I am not able to do much to affect rolling resistances, which will
take up a large portion of HP to overcome, but I can make the body as
aerodynamic as possible, and if I have to use RWS to do so, OK, the gain in
speed is worth it....
At 12:10 PM 6/7/00 , you wrote:
>for what little it is worth.....Rear steer??
>Don't airplanes turn primarily with the ailerons and the rudder????? Oh
>yeah don't they also move in 3 dimensions during a turn??? Don't they
>have a lot of sky to turn in ??? Rudder on the front?? aren't they
>actually doing thrust vectoring from the prop more than ruddering as in
>a sailboat. if you put the prop in front with the rudder might work just
>fine as long as you went slow enough to keep it in the water. My
>powerboat turns in 2 dimensions other than very slow at the dock when in
>fact it is usually easier to back in than turn into the slip. BTW
>everyone I know that has a twin engine boat can get more steering from
>differential power that the rudder..And larger boats have thrusteres in
>the bow so they can steer precicely. I think the reason they use rear
>steer is it is the end most likely to stay in the water!!!!!My car on
>the other hand turns in 1 dimension has very little pitch roll or
>yaw...maybe you need a racecar with a hard chinned bottom to make this
>all work LOL
>
>What was the downside again to turning the driven wheels???if you have
>to have front wheel drive.....If you have to have front wheel drive
>strctly for areo i think someone needs to go back and get their
>calculator out and figure out how much of the road load is areo and how
>much is rolling resitance.. me thinks you are fixing the wrong part in
>the first place. Even the drive train loss is in many cases more than
>the aero
>Dahlgren
>
>Dick J 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
> > >
> > >
> >
> > __________________________________________________
> > Yahoo! Photos -- now, 100 FREE prints!
> > http://photos.yahoo.com
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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