Russ,
I am impressed by your resume. I don't consider myself an expert at
anything, but I do have an opinion concerning this discussion.
1. Rooster tails on the salt are not from wheel spin - it is caused by
the vacuum created behind the car. The severity of the rooster tail has
much to do with how much loose salt is on the course. I say this because
of experience in a low HP car that rarely spins its wheels but generally
carries a tail from about the one mile.
2. I am not in favor of anything that takes the absolute control of the
car away from me for any reason. Otherwise why drive, let's put robots
in the driver's seat. Driving is what it is all about, if it wasn't I
doubt if many of us would bother to make the trip.
3. After talking to Earl Wooden, I don't believe his problem was wheel
spin, rather, I suspect, it was extreme loading of the tires from
applied HP that was well hooked up. The flexing of a well hooked up tire
will create more heat than a spinning one, in my opinion. Would traction
control correct the problem? I don't think so.
4. Undoubtedly, the most powerful sedan on the Salt this year was the
Lindsley/Leggitt Firebird, 333 MPH in the middle mile. So far as I know
the only tire problem they had was front tire shredding, again loading,
this time from downforce.
Yes Earl was lucky! It is curious when you compare his crash to Tom
Burkland's. The speed was much different, but the results similar,
actually Tom's injuries were worse than Earl's. You don't have to be
going 300 MPH to get hurt. That is why I worry about the 130 MPH Club
cars at the World of Speed. We had a fatality at the Lakes in 1962 when
a Pinto crashed at about 140 MPH. (At that time we had a 140+ MPH roll
bar rule.)
I have been doing crazy this stuff since the middle fifties. I have seen
many changes in Safety Requirements and I applaud those that have made
it happen. Most of our Safety Rules have been ushered in by blood, even
lost lives, but none so far take total control of the car away from the
driver. To quote one of Murphy's Laws, "You can't make things fool safe,
fools are to ingenious."
I do appreciate your comments. I just don't think that you really
understand what we do.
Tom, Redding CA - #216 D/GCC, (still reaching toward the distant 300 MPH
barrier.)
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
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