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
///
/// land-speed@autox.team.net mailing list
/// To unsubscribe send a plain text message to majordomo@autox.team.net
/// with nothing in it but
///
/// unsubscribe land-speed
///
/// or go to http://www.team.net/cgi-bin/majorcool
///
///
|