Dave:
You are proposing exactly what I'd hoped for. Note that I gave an estimate for
an
expensive "do it yourself", and for a much cheaper "do it with the help of the
electronic
speed parts suppliers". I assure you, I'd much rather do it your way! And you
are one
of the people I hoped would get interested, because between you and your
colleagues,
maybe our whole sport could be cheaply and easily supplied.
Personally, I'd want just a little more processing power-- I think we will
probably need
to work from trailing average values rather than from instantaneous ones (as
"Pork pie"
mentions elsewhere, I think the wheelspin varies quite a bit (even in a short
distance)--
because of the high speeds and the dips in the surface.
And 4-wheel drive folks would need even a little more sophistication-- perhaps
basing the
engine limiter on torque drops, rather than wheel speed differences.
Russ
Dave Dahlgren wrote:
> I am for it but if it runs the throttle or brakes count me out....There are
>ways to
> control tire spin that do not effect either.. If a guy wanted to build a
>simple
> traction control all you need to do is this...
> measure the wheel speeds front and rear
> If the speeds are different by more than a preset amount you can do one of
>two things
>
> activate a light that informs the driver he is spinning more than he should
>and let
> him make the decisions
> or
> activate a soft rev limiter that will slow the engine down so the tires can
>catch
> up...
>
> Well Russ you seem to think this will cost a ton of money 5k or more.. I beg
>to
> differ..
> you use one chip to turn the frequency to to a voltage about 1.00 each
> you use an op amp to subtract the undriven wheel voltage from the driven wheel
> voltage 0.39
> you use a comparator to see if the difference is greater than the set point
>uses same
> chip you bought for 0.39
> you adjust the set point with a trim pot 0.15
> you need a little wire and a case to put it in maybe 5.00
> oh I forgot the voltage reference a chip about 1.50 and a few resistors and
>caps
> >1.00
> So it is a 10.00 project.... you can use the rev limiter on the msd that is
>used for
> staging the car.... it is voltage activated..
>
> See cheap and does not fool with the throttle or brakes.. By the way there
>may be a
> patent pending on this idea so I would not go into full scale production this
> afternoon.. :>)....
> Dave Dahlgren
>
> rtmack wrote:
>
> > List:
> > Most of you don't know me very well. Just this once I'd like to tell you
>"where
> > I'm coming from", hoping that you'll give some credibility to these ideas
>on a
> > subject that I think is critical to the safety of our racers. I am a
>mechanical
> > engineer-- semi-retired now-- and I spent about half my career in automotive
> > research (Southwest Research Institute, San Antonio). Among my other
> > assignments, I conducted guardrail car crash tests, and I tested automobile
>tires
> > on a tire dyno. (Most of the rest of my career was spent in test and
>measurement
> > in the petrochemical industry.) I'm a former AMA motocross racer who has
>had
> > some minor involvement in circle track racing and NHRA Federal Mogul Funny
>Cars.
> > I am a volunteer worker in the CART racing series. I am currently
>dusting-off my
> > driving/riding skills, and I hope to build my own LSR machine. This year I
> > crewed for Skip Higginbotham and Bill Smith on the "Yellow Rose of Texas"
> > record-setting AA Lakester.
> >
> > Now for the subject:
> >
> > During the summer we had one thread going about the difficulty of getting
> > reliable high speed tires, and another about whether or not SCTA should make
> > traction control (TC) legal. I've been thinking a lot about both issues
>since
> > then, and I'd like to re-open the discussions. I hope some of you will
>jump back
> > in.
> >
> > In my two trips to Bonneville this summer, I heard-- and personally
>observed--
> > that many of the most powerful cars were plagued with drive-tire blisters,
> > throwing tread, circumferential growth (plastic strain) and even blowouts.
>(At
> > the end of this letter, you'll find Joe Timney's previous letter to the
>list that
> > cites the scariest example of this problem.) The problem was not just with
>Earl
> > Wooden's car-- it actually seems to be very widespread among the cars over
> > 300mph.
> >
> > There was an earlier suggestion on the list that we try to get the tire
>providers
> > to produce a better product for us. Having watched dozens of salt
>"roostertails"
> > (lasting almost 5 miles, in some cases), I don't believe that there is very
>much
> > that the tire manufacturers can do for our high speed tire failures. As Joe
> > Timney suggests below, technology probably doesn't presently exist to
>produce
> > tires that will maintain a safety margin for a 5-mile burnout (finishing
>over
> > 300mph). The most powerful machines are capable of literally abrading the
>best
> > pair of tires to death in much less than 5 miles!
> >
> > The other way to address the problem is to limit the amount of drive-tire
>spin.
> > Our racers have used several techniques to try to accomplish this. Other
>than
> > suspension/ chassis setup, reducing aerodynamic drag, or having the driver
>use
> > less than full throttle-- most everything we do (reducing tire pressure,
>adding
> > ballast, aero downforce, etc.) stresses the tires just that much more. I
>don't
> > believe that we can hope to reduce tire failures by reducing tire pressure,
> > adding ballast, or increasing downforce beyond the values that our fastest
>cars
> > are currently using.
> >
> > Most racers have already done everything within their power to reduce
>aerodynamic
> > drag-- so I think most would not find that a productive area to work on
>(unless
> > you want to invest in some expensive wind-tunnel time). Many of our cars
>could
> > probably benefit from better suspension / chassis setup (see Bill
>Hoddinott's
> > interview with Chuck Salmen-- published on this list in 1999). However, we
>can
> > probably only gain a little with these improvements; many machines would
>likely
> > still retain the ability to shred their tires in one pass.
> >
> > The obvious answer is in the throttle-- as we keep hearing at the starting
>line,
> > "it works both ways". One difficulty in that concept is that some machines
>seem
> > not to give the driver sufficient feedback so that we know how much spin
>we're
> > getting. And most of us probably can't judge how much spin is too much--
> > especially if the car is tracking straight and not otherwise acting too
>scary.
> > And many LSR drivers are dominated by the thrill of speed, and only want to
>hold
> > the pedal on the floor, even if the car is "wagging its tail"! I think that
> > there is only one way to allow the drivers to go "all-out", and still
>minimize
> > the risk of tire failure. I think that the only way to accomplish this
>reliably
> > is to compute the optimum power delivery values, "on the fly", real-time--
>and to
> > automatically make the needed adjustments to the power delivery.
> >
> > I'm talking about Traction Control.
> >
> > I'm asking you to consider TC as a safety issue-- in terms of the potential
>for
> > preventing the injury or death of some of our fastest drivers, due to high
>speed
> > tire failures. Yeah, Earl Wooden came out of that bad wreck pretty good.
>The
> > safety rulemakers deserve their pat on the back-- as do the inspection
>folks-- as
> > does the builder-- as does Earl, for keeping himself in such good shape.
>But
> > let's not forget that Earl was damned lucky, too! Look at the Speedvision
>film a
> > few times ...see the chaos of a 300mph crash? We can't build anything that
>will
> > assure that the driver will survive these. We can't predict all the things
>that
> > can happen, all the places that the kinetic energy will be expended. As
>much as
> > possible, WE HAVE TO PREVENT THESE HIGH SPEED CRASHES. I think that TC is
>the
> > most powerful crash prevention tool at our disposal for reducing the
>potential
> > for high-speed tire failures in Land Speed Racing.
> >
> > I have been discussing this proposal "off-list" with Bill Hoddinott
> > ("Ardunbill"). Bill points-out that many LSR people are afraid that
>legalizing
> > TC will guarantee that many of the top landspeed records will go to the
>big-money
> > people. I am not convinced of that. A big percentage of the (not rich) hot
> > rodders already on the salt have already mastered harder (and more
>expensive)
> > technical problems. I know several people who could design, build, and
>program a
> > system in a couple of months, from scratch. I estimate the cost to be from
>$5k
> > to $15k.
> >
> > Better yet, if we could get SpeedPro, MSI or Edelbrock to make an
>inexpensive mod
> > to computerized systems that many competitors already have aboard, we would
>only
> > need to spend from $100 - $300 for sensors and a servo... plug it up.. and
>go
> > nail the throttle! In fact, I would not be surprised if one or two
>competitors
> > have already accomplished this. The claim that only the rich guys cars (or
> > factory sponsored cars) could compete for records in TC-legal classes has no
> > basis in fact. It is, as they say ... "bogus".
> >
> > Bill also pointed-out that many competitors feel that this computer-based
> > technology has no place in the vintage classes. On that point I agree--
>vintage
> > class needs vintage technology, if we are to maintain the value of those
> > classes. I have no solution to propose for the roadsters, etc. (and the
>fastest
> > ones have the same tire problem). But surely we can allow this safety
>feature
> > for those very fast "special construction" vehicles, modified sports, bike
> > streamliners, etc.--?? If TC can keep even one of our drivers from a 300mph
> > crash, I think it is worth the effort.
> >
> > I invite comments from any and all. My hope is to build a little "grass
>roots"
> > momentum toward proposing legalization.
> >
> > Best Regards,
> > Russ Mack
> >
> > Joe Timney wrote:
> >
> > > List,
> > > John Beckett and I got to look over Earl's car with Jim Miller and a
> > > couple of things stood out. The drive train is off-set to the right and
> > > he blistered a right rear tire the day before. The car had a lot on lead
> > > mounted in front of the rear. He was running Goodyear Landspeed
> > > tires...brand new!!! There were chunks off the center. Earl was
> > > traveling at 288 out of the four mile...obviously that tire was loaded
> > > and probably spinning...I'd like to see a data acquisition readout on
> > > that run. One can not expect to see any tire take that kind of abuse. I
> > > have seen drag slicks spin in the lights and get a slight
> > > blister...guess what...they either fail soon after that or they change
> > > circumference, then fail!
> > >
> > > I wonder out loud if Keith's tire circumference issue was also a
> > > heat/spin/load relationship???
> > >
> > > I'd also like to publicly thank Jim Miller for the opportunity to "learn
> > > for the remains". Looking at how the structure held up and bent, taught
> > > me a couple of "must do's" when designing future projects.
> > >
> > > joe
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