"06" Lake Gairdner traction

[stayt`ie]

this is a question to the u.s. racers and visitors that were at our 06speedweek event,,, " at what surface friction coefficient would you rate our salt this year : "

[landracing]

about the same as wet salt here.... Slippery....

Jon

[joea]

yep......similar to Bonneville when wet..........

similar to many entities..........."slippery when wet"........

[stayt`ie]

yes it was slippery , but how slippery?  i noted that your bikes didnt run near the speeds that you do on  "wet" salt at bonneville,  this may  have been due to other factors?,,   what i am trying to establish here ( what was asked in my initial post) that is, salt friction coefficient #.    ok,  .6 is the accepted number for good salt, then it can varie all the way down to .2, you fellas have had many years running on various "wet" salt conditions, soooo,,,, "what would you rate our 06 salt at" :

[Dr Goggles]

Hi ronnie
there must be a pretty simple way of standardizing the traction coeficient .....a strain guage , a standard weight and a standard surface area of a known compound ( say smooth rubber) would be a reasonably simple way for to get a "feel" for the actual figure....anyone?

or to put it another way , dad how does this work?......does someone out there have a simple explanation of how the C of traction is calculated and how a basic device could be built to give relative readings.

[Sumner]

yes it was slippery , but how slippery?  i noted that your bikes didnt run near the speeds that you do on  "wet" salt at bonneville,  this may  have been due to other factors?,,   what i am trying to establish here ( what was asked in my initial post) that is, salt friction coefficient #.    ok,  .6 is the accepted number for good salt, then it can varie all the way down to .2, you fellas have had many years running on various "wet" salt conditions, soooo,,,, "what would you rate our 06 salt at" :

The friction coeffiecient will even change during the day.  What appears to be the same salt at 8 in the morning and 2 in the afternoon is not.  I guess you just have to work with what you got when you get to the front of the line .

c ya, Sum

[stayt`ie]

that you do sum , it can also varie from start to finish at any time of the day..  but this is all part of the generaliziation of the conditions at the time, thus we have a coefficient number that gives us a level/figure of grip/slipperyness ie. traction to work with ...

[Seldom Seen Slim]

Okay, okay, so somebody come up with a repeatable set of test conditions, do your coefficient testing and determine some number, and report both the result of the test and the conditions.

For instance:  Test 1:  Bonneville Salt Flats, 9 AM, 78 F/12% humidity, sunny all day yesterday, no rain for XX days (months), salt generally described as "good", test made at the four mile:  Result was Coeff/ Traction = .63

Test 2: Lake Gairdner, 3 PM, 34 C/8% humidity, partly cloudy today, rain squalls last Monday, salt generally described as "okay but not great", test made at the start line:  Result was C/T = .38

All tests performed by dragging a "standard" (brick, old tire, case of diet coke, whatever) weighing "so many pounds/kg" and measuring the resistance in pounds/kg/slugs/whatever and converting by a set factor.  

Or whatever -- the idea is to define the conditions enough that the results are at least somewhat repeatable, by defining as many of the variables as possible no matter what they might be at that moment.  If we all know what those basic conditions are -- we could all interpret the results.

Yes, of course the conditions vary all over the Salt, and yes, anecdotal reports are very subjective -- so a set of conditions for a test help resolve those conditions into something from which all could benefit.

Okay, let the arrows fly!

[Sumner]

Okay, okay, so somebody come up with a repeatable set of test conditions, do your coefficient testing and determine some number, and report both the result of the test and the conditions.

I nominate that "Seldom Seen Slim" guy , do I hear a second ,

Sum

[dwarner]

Why don't you just get in/on it, push or twist the throttle, keep the tire/tires under it and read the time slip?

DW

[Rick Byrnes]

I like that Warner

[Sumner]

Why don't you just get in/on it, push or twist the throttle, keep the tire/tires under it and read the time slip?

DW

When you get to the head of the line that is about your only choice, isn't it ,

Sum

[Seldom Seen Slim]

I do it Dan's way -- I was just trying to offer a way of quantifying the situation for anyone that does't choose to so do.

[edweldon]

This is a real interesting subject.  Engineers like me like to put numbers on things.  It might be interesting to run some simple friction coefficient tests and see if there's any correlation with the way the cars run.  I think I'll bring my 2000# sherline scale (see attachment) and some smaller ones with me this year and in the meantime think about how to set up some simple tests.  Any ideas anyone?
Ed Weldon

[Sumner]

I do it Dan's way -- I was just trying to offer a way of quantifying the situation for anyone that does't choose to so do.

I thought you said we could shoot arrows at you .  Guess we didn't give you enough time to get your vest on .



Well looks like you are out of the woods.  This guy already developed the device to measure traction.  Only problem is he used 5 different surfaces, but none were salt . I learned some from his site ( HERE ), but some of this still confuses me .  

One interesting thing was

....increasing wheel number decrease weight per wheel, keeping vehicle traction constant....

.  He noted the exception to this is

Of course this applies only on a solid, reasonably even ground. More wheels may be needed to spread load on a larger surface (mud, sand...), but to maintain pulling capability as many of them as possible should be driven.

.  So does this mean a wider tire with more footprint won't increase traction since the weight will decrease per square inch of footprint?

So when it is all over if you are spinning your tires you need weight and if not you need HP and you are still stuck with the current conditions when it is time to go, so just follow Dan's instructions .

c ya, Sum