Author Topic: Rolling Resistance  (Read 31212 times)

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Offline John Noonan

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Re: Rolling Resistance
« Reply #15 on: June 04, 2008, 10:08:45 PM »
I'd like to know more about the motivation behind the public display of righteous indignation "I pressed the ignore button".
This is, of course, the exact opposite of ignoring him, but instead commenting on him rather than his post.


It may be a way of publically admitting that you have had enough..just the ****teen people currently.

Any idea of recent pumping on the salt? ?

J

MCR

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Re: Rolling Resistance
« Reply #16 on: June 27, 2008, 06:55:40 PM »
OK, I'll bite:

3000kg*200km/h*.025(t)/270 = 56

56 kw?  hp?  fig-newtons?

MCR

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Re: Rolling Resistance
« Reply #17 on: June 27, 2008, 07:04:54 PM »
I do know that tire design has a far greater impact than surface texture does on most racetracks.

Example, 3360lb car goes down the dragstrip on steel radials, nets 118mph.  Switch tires to bias ply DOT racing tires, and trap speed goes to 116mph.  In this performance envelope, each MPH is about 10rwhp on a dyno, so 20 rwhp additional power was consumed.

The formula in the first post yields "10".  Even if it were kw, it's still less than the extra loss going from steel to fabric, and soft to medium compounds.  Tire pressure was the same, 20 PSI.


Ratliff

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Re: Rolling Resistance
« Reply #18 on: June 28, 2008, 10:53:31 AM »
I do know that tire design has a far greater impact than surface texture does on most racetracks.

Example, 3360lb car goes down the dragstrip on steel radials, nets 118mph.  Switch tires to bias ply DOT racing tires, and trap speed goes to 116mph.  In this performance envelope, each MPH is about 10rwhp on a dyno, so 20 rwhp additional power was consumed.

The formula in the first post yields "10".  Even if it were kw, it's still less than the extra loss going from steel to fabric, and soft to medium compounds.  Tire pressure was the same, 20 PSI.



To extend your conclusions to other surfaces, you would first have to do that same experiment with the same car and same tires at Bonneville, El Mirage, etc THEN compare the results to pavement. It is possible on softer surfaces the results could be much less pronounced, or just the opposite.
« Last Edit: June 28, 2008, 11:41:31 AM by Ratliff »

Offline Roadsters.com

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Re: Rolling Resistance
« Reply #19 on: June 28, 2008, 12:17:06 PM »
I copied this from the Forum Rules: "Condescending, rude, and annoying remarks and insults will not be tolerated."

The only worthwhile posts in this thread are about calculating rolling resistance. The rest of them illustrate why I forgot about this place for years and almost never post here.

Dave Mann
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http://www.roadsters.com/

MCR

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Re: Rolling Resistance
« Reply #20 on: June 28, 2008, 01:08:41 PM »
I'm a new member on this board, but not new to performance website forums or racing.

This is intended as purely helpful advice:

If you want participation on a forum, trashing folk for posting tech info is a terrible thing.

Basically it show casual readers that they are not welcome to post.  No posting = no readers.

Me, I have a thick skin.  Most folk don't.

It's free advice, so worth every penny you spent on it... ;)


Offline Seldom Seen Slim

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Re: Rolling Resistance
« Reply #21 on: June 28, 2008, 04:05:38 PM »
Dave, I thank you for visiting landracing.com.  I'm Jon, the new owner of the site, and I do appreciate not only that you've chosen to stop here for a while -- but also your reasoning for having abandoned the place in the past.  I'm sorry that on your first visit in a long time you find stuff that's -- that's -- well, stuff that sure isn't what we want to have on the site.  I'm trying to ride herd without getting to intrusive/cutting folks off.  But when I see your comments I feel that maybe I've been lax in allowing some of the stuff to go on when I should have cut it out.

To the others of you that post here on a regular basis -- gee-zul-man, please think about what you're posting.  Land speed racing stuff is what we want -- moronic activities and actions and words aren't what belongs here. 

Thanks, Dave -- and I hope you find it worth a visit now and then to see if you can put up with us for another day.
Jon E. Wennerberg
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Ratliff

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Re: Rolling Resistance
« Reply #22 on: June 28, 2008, 04:14:18 PM »

Disabling the ignore button may not be a bad idea.

Offline desotoman

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Re: Rolling Resistance
« Reply #23 on: June 28, 2008, 05:21:10 PM »

Disabling the ignore button may not be a bad idea.

What does that have to do with Rolling Resistance?

Tom G.
Asking questions is one's only way of getting answers. As a young boy I was always taught that there is no such thing as a stupid question. It suggests that the quest for knowledge includes failure, and that just because one person may know less than others they should not be afraid to ask rather than pretend they already know. In many cases multiple people may not know but are too afraid to ask the "stupid question"; the one who asks the question may in fact be doing a service to those around them.

Offline Seldom Seen Slim

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Re: Rolling Resistance
« Reply #24 on: June 28, 2008, 08:39:11 PM »
Franklin, I had thought that you were "getting better"about not posting too much stuff and not being too far from the topic du jour -- but you're honing a scab on your behind, to paraphrase something my mother used to use.  Please do stick to land speed stuff and not go off on personal rants, and quoting all of the old data may be informative to some -- but not really germaine to the purpose of landracing.com.  I expect you'll claim that others appear to be doing just what I'm asking you to not do -- and that's not anything I want, either.  But concern yourself with you and not them.

Please straighten up and fly right, using another phrase, or I'll use the big ignore button on you.  Understand me this time?
Jon E. Wennerberg
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Offline comp

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Re: Rolling Resistance
« Reply #25 on: July 07, 2008, 07:21:45 PM »
 guick question ,, are these # for a slick tire ??

Offline Lucky 7

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Re: Rolling Resistance
« Reply #26 on: August 04, 2008, 07:07:08 PM »

The estimate for T on wet salt at Bonneville is .04 to .05
 
This is an older formula but should still give useful results.

Can I ask what is the estimate for dry salt, or is that being too optimistic?

What are the other formulas, and how much do the outcomes vary from one formula to another?

saltfever

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Re: Rolling Resistance
« Reply #27 on: September 10, 2008, 05:59:48 PM »
Can I ask what is the estimate for dry salt, or is that being too optimistic?

What are the other formulas, and how much do the outcomes vary from one formula to another?

Probably too optimistic. :-) Salt is hygroscopic (it attracts water). In the 18 years I have been going there I have yet to see dry salt. During the middle of the day it may appear to be dry and hard but it is deceptive. If you sit or kneel on it your pants will develop a wet spot instantly. Larry Mayfield (Dr. Mayf) did some salt-friction studies a few years ago but I never heard the final results. Maybe he posted here in the past or he will chime in here.

Offline Seldom Seen Slim

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Re: Rolling Resistance
« Reply #28 on: September 10, 2008, 07:47:02 PM »
Also worth remembering is that the salt usually gets more moist (repeat MORE moist) as the day progresses.  The heat of the sun warms the surface and also the water just below the surface, which expands, which means the salt surface gets wetter in the heat.  It's contrary to what you'd expect -- but it does happen.

Morning runs have good traction, as a rule of thumb, and afternoon runs have thinner air...both because of the heat of the day.
Jon E. Wennerberg
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canadianrocky

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Re: Rolling Resistance
« Reply #29 on: September 19, 2008, 01:52:48 PM »
Dave, I thank you for visiting landracing.com.  I'm Jon, the new owner of the site, and I do appreciate not only that you've chosen to stop here for a while -- but also your reasoning for having abandoned the place in the past.  I'm sorry that on your first visit in a long time you find stuff that's -- that's -- well, stuff that sure isn't what we want to have on the site.  I'm trying to ride herd without getting to intrusive/cutting folks off.  But when I see your comments I feel that maybe I've been lax in allowing some of the stuff to go on when I should have cut it out.

To the others of you that post here on a regular basis -- gee-zul-man, please think about what you're posting.  Land speed racing stuff is what we want -- moronic activities and actions and words aren't what belongs here. 

Thanks, Dave -- and I hope you find it worth a visit now and then to see if you can put up with us for another day.

Jon,

I have belonged to several different sites that have completely different focuses from this one. When it comes to staying on topic, relevant comments to the topic and the information on the site that is helpful, this is the best one I have seen.

Even though I have not started my project, the information I have received so far has been invaluable. I have also made many contacts that will make the project much easier to get through.

I know that when I get to the Salt, that it will be an extension of the time I have spent here, first.

I wouldn't get to heavy with the edit button, those that are wasting others time on the site know who they are, and there really are not enough of them to sweat it.

Rocky