Dagger GT
07-05-2010, 10:56 AM
#32
Registered User
Join Date: Aug 2008
Posts: 862
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Mr.E.G.,Jul 5 2010, 12:28 PM
You are mistaken about some of what you claim, which I will address in detail momentarily, but I want to start by addressing your last sentence. I could just as easily end my rebuttal by saying, "If you actually did study two years of physics you should know this," but I think we can both agree that such a phrase would be a bit condescending. Naturally, I'm not exactly pleased that you felt the need to evoke such a tone in an otherwise friendly discussion and I'd appreciate if this were the last of it.
First of all, you are speaking of all racing tires as if they all have a single goal in mind when, as you are well aware, there are a variety racing tires that do different things better or worse than others. You can generate more friction between two smooth surfaces than you can two smooth surfaces with some debris in between them, sure, but reality doesn't only come in those two flavors, contrary to your explanation. Do you really think that a train with regular train wheels could generate the same forward traction that a train with cogs for wheels and a slotted track could? Why do gears have teeth if they could just press two smooth metal discs against each other and they could use friction to accomplish the same?
I went back through some of my books to find out which of them I borrowed that anecdote from and it actually came from the Fred Puhn book (which I think we can all agree is a reputable source, albeit a bit elementary) on page 13.
And I quote, "It says in some science books that the coefficient of friction can never be larger than 1.0... Drag racers proved otherwise, as they broke these "impossible" limits... The drawing shows (there's a drawing in the book that illustrates this) interlocking of the tire tread with the road surface. The softer the rubber compound, the more the interlocking and the more grip is increased..."
Come one now, I never said anything to the contrary. You said that it takes top fuel equipment to come close and I merely pointed out that you can get close without going that extreme.
In regards to why cogs/gears are used, it's a very different situation, is it not? Not all surfaces are good for adhesion. Metals are generally terrible at it. Also, there's a durability issue. Tires wear out rather quickly and that's not great for every situation.
Regardless, I can assure you that tires use adhesion. Here's a few quotes if you don't believe me: "They mean that, on concrete, my tire gave me gees of sideways resistance before sliding. On a linoleum race course (ahem!), I would only be able to get . We have directly experienced the physics of grip with our bare hands. The fact that the tire resists sliding, up to a point, is called the grip phenomenon. If you could view the interface between the ground and the tire with a microscope, you would see complex interactions between long-chain rubber molecules bending, stretching, and locking into concrete molecules creating the grip. Tire researchers look into the detailed workings of tires at these levels of detail." Molecules locking together clearly = adhesion.
Or, straight from Wikipedia: "Traction is another name for the adhesive friction between two surfaces."
Drag radials were able to achieve coefficients of friction above 1 precisely because of adhesion.
Finally, I'm sure there are some drag radials that are used for non-top fuel dragsters that can achieve 1.8+ g's of acceleration. However, that's just picking on me for semantics. My point was clear. Outside of very nice drag radials you won't be able to achieve those numbers. You initially pointed to a car that supposedly achieved sub-2 second 0-60 times on street tires, so I assumed you were trying to prove it was possible on the street.
07-05-2010, 07:23 PM
#36
If they instead only manage 1200-1500 bhp, 0-60 in the low 2 second range (which is meaningless anyways--1/4 mile is short for this kind of car), and hit a 250+ mph top speed, this car will be nothing short of awesome. So if they miss their crazy marks and get close, I will still be impressed. And never buy one.
And it does look cool.
And it does look cool.
07-06-2010, 10:21 AM
#37
Registered User
Join Date: Aug 2003
Location: SLC, UT
Posts: 3,170
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by RC 94,Jul 3 2010, 10:47 AM
0-60 in 1.5 seconds? I'ma call BS on that.
07-06-2010, 10:25 AM
#38
They may get those times but to do so, they'll have to run the car in a configuration that completely compromises its ability to handle. In other words, even with stick road-racing slicks, you won't get those times in a straight line. Using drag slicks (DOT approved, even) won't give you cornering ability.
In short, they're listing performance numbers that are impossible (yes, I said it) in a single vehicle configuration. They'll have to change the suspension, change the tires, and change the aero to remotely think about doing everything they're saying (ie, for acceleration, it'll be set up one way, for grip it'll be another, for road racing it'll be another, etc, etc).
In short, they're listing performance numbers that are impossible (yes, I said it) in a single vehicle configuration. They'll have to change the suspension, change the tires, and change the aero to remotely think about doing everything they're saying (ie, for acceleration, it'll be set up one way, for grip it'll be another, for road racing it'll be another, etc, etc).
07-06-2010, 10:49 AM
#39
Originally Posted by tarheel91,Jul 5 2010, 10:56 AM
I wasn't trying to come off as condescending. I apologize if it sounded that way. The internet is terrible at conveying tone. I only put 2 and 2 together at that point and it was a last minute note.
In regards to why cogs/gears are used, it's a very different situation, is it not? Not all surfaces are good for adhesion. Metals are generally terrible at it. Also, there's a durability issue. Tires wear out rather quickly and that's not great for every situation.
Regardless, I can assure you that tires use adhesion. Here's a few quotes if you don't believe me: "They mean that, on concrete, my tire gave me gees of sideways resistance before sliding. On a linoleum race course (ahem!), I would only be able to get . We have directly experienced the physics of grip with our bare hands. The fact that the tire resists sliding, up to a point, is called the grip phenomenon. If you could view the interface between the ground and the tire with a microscope, you would see complex interactions between long-chain rubber molecules bending, stretching, and locking into concrete molecules creating the grip. Tire researchers look into the detailed workings of tires at these levels of detail." Molecules locking together clearly = adhesion.
Or, straight from Wikipedia: "Traction is another name for the adhesive friction between two surfaces."
Drag radials were able to achieve coefficients of friction above 1 precisely because of adhesion.
Finally, I'm sure there are some drag radials that are used for non-top fuel dragsters that can achieve 1.8+ g's of acceleration. However, that's just picking on me for semantics. My point was clear. Outside of very nice drag radials you won't be able to achieve those numbers. You initially pointed to a car that supposedly achieved sub-2 second 0-60 times on street tires, so I assumed you were trying to prove it was possible on the street.
In regards to why cogs/gears are used, it's a very different situation, is it not? Not all surfaces are good for adhesion. Metals are generally terrible at it. Also, there's a durability issue. Tires wear out rather quickly and that's not great for every situation.
Regardless, I can assure you that tires use adhesion. Here's a few quotes if you don't believe me: "They mean that, on concrete, my tire gave me gees of sideways resistance before sliding. On a linoleum race course (ahem!), I would only be able to get . We have directly experienced the physics of grip with our bare hands. The fact that the tire resists sliding, up to a point, is called the grip phenomenon. If you could view the interface between the ground and the tire with a microscope, you would see complex interactions between long-chain rubber molecules bending, stretching, and locking into concrete molecules creating the grip. Tire researchers look into the detailed workings of tires at these levels of detail." Molecules locking together clearly = adhesion.
Or, straight from Wikipedia: "Traction is another name for the adhesive friction between two surfaces."
Drag radials were able to achieve coefficients of friction above 1 precisely because of adhesion.
Finally, I'm sure there are some drag radials that are used for non-top fuel dragsters that can achieve 1.8+ g's of acceleration. However, that's just picking on me for semantics. My point was clear. Outside of very nice drag radials you won't be able to achieve those numbers. You initially pointed to a car that supposedly achieved sub-2 second 0-60 times on street tires, so I assumed you were trying to prove it was possible on the street.
I'm beginning to think we are arguing the same point and getting lost in the semantics.
What is it that you are trying to state exactly? I took your comments to mean that coefficient of grip higher than 1.0 was not obtainable to which I which I stated that the theoretical limits of what smooth rubber and smooth concrete (asphalt, whatever) does not match the reality due to the interlocking of the materials, even on the macro level. Of course on some microscopic level interlocking occurs but I don't think that's what either of us was talking about. Now it seems that you are agreeing with that. What's happening exactly?
07-06-2010, 11:08 AM
#40
Originally Posted by Mr.E.G.,Jul 6 2010, 02:49 PM
What's happening exactly?