Re: [EVDL] EVLN: Venturi, OSU VBB-3 Electric Racer targets 372mph record 0-60mph:2s

[Bill Dube via EV]

2) It removes a thin layer of aged hard rubber, 
and reveals fresh soft sticky rubber.


If it removes a layer of rubber wouldn't that also remove the TrackBite?Â


They spray the track with TrackBite, not 
the tire. You do a burnout principally to remove 
this aged layer of rubber, particularly on the 
first run of the day. On subsequent runs, you can 
do a smaller burnout to just heat the tire surface.


For a national event, they spray the 
entire 1/4 mile length of the track. For a  local 
bracket race, they just spray the launch area. 
Maybe 100 ft. Whole different procedure.


Track surface preparation is an art. 
They first clean the track surface with a rotary 
sweeper. Then they spray the track with a layer 
of TrackBite. Then they apply a thin coating of 
rubber dust. Next, they burnish the surface with 
a set of counter-rotating drag racing slicks. 
Finally, they apply a very light final spray of TrackBite.


When the track is prepared optimally, 
the traction (adhesion) is so great that you will 
actually spall off little pieces of the 
underlying concrete. Basically, the you exceed 
the shear strength of the pavement material itself.


Bill D. 
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Re: [EVDL] EVLN: Venturi, OSU VBB-3 Electric Racer targets 372mph record 0-60mph:2s

[Chris Tromley via EV]

Years ago when I was paying attention to this stuff, road racers on slicks
could pull 1.2g and higher without any special 'TrackBite'-like coatings on
the track.  I remember 2g in some situations, but I don't remember if
banking was involved.

The theory behind coefficient of friction is based on a laboratory test of
one material against another.  Both materials are smooth.  There is no
rolling involved, just flat surfaces either static or sliding against each
other.  Theoretically you can't get better than 1g, which is borne out is
tests under these conditions.  Sticky tires are also soft and gummy,
meaning they interlock with the pebbly surface of asphalt.  I believe there
is also an improvement from (slight) slippage due to overspeed on
acceleration.

This disconnect is a case of the model (the laboratory test) not matching
the actual situation (rolling slicks on asphalt).  The fact that street
tires get a coefficient of 1 is probably a coincidence.  They can't have
the grip of slicks because that would require too many compromises.  Like
not being as gummy, so not as much interlock.

Chris

On Thu, Feb 11, 2016 at 3:52 PM, Bill Dube via EV  wrote:

>
> 2) It removes a thin layer of aged hard rubber, and reveals fresh soft
>> sticky rubber.
>>
>> If it removes a layer of rubber wouldn't that also remove the TrackBite?Â
>>
>
> They spray the track with TrackBite, not the tire. You do a
> burnout principally to remove this aged layer of rubber, particularly on
> the first run of the day. On subsequent runs, you can do a smaller burnout
> to just heat the tire surface.
>
> For a national event, they spray the entire 1/4 mile length of the
> track. For a  local bracket race, they just spray the launch area. Maybe
> 100 ft. Whole different procedure.
>
> Track surface preparation is an art. They first clean the track
> surface with a rotary sweeper. Then they spray the track with a layer of
> TrackBite. Then they apply a thin coating of rubber dust. Next, they
> burnish the surface with a set of counter-rotating drag racing slicks.
> Finally, they apply a very light final spray of TrackBite.
>
> When the track is prepared optimally, the traction (adhesion) is
> so great that you will actually spall off little pieces of the underlying
> concrete. Basically, the you exceed the shear strength of the pavement
> material itself.
>
> Bill D. -- next part --
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Re: [EVDL] EVLN: Venturi, OSU VBB-3 Electric Racer targets 372mph record 0-60mph:2s

[Jack Wendel via EV]

>
> I though I heard of sub 3 second time reported, not theorized.
>

I recently read of a car that does 0 - 60 in 2.2 seconds. Tesla is FAR from
optimum.

>
> I have never gotten an explanation I could understand of how C_friction can
> exceed 1 as I have heard regarding dragsters.
>

I'm not sure why you would assume 1.0 is the mas coefficient of friction
possible.  Just aluminum to aluminum can be as high as 1.35.

Friction Coefficients for some Common Materials and Materials Combinations
Materials and Material CombinationsStatic Frictional Coefficient
-
*μs -*
Clean and Dry SurfacesLubricated and Greasy Surfaces
Aluminum Aluminum 1.05 - 1.35 0.3
 http://www.engineeringtoolbox.com/friction-coefficients-d_778.html


The reason high horsepower drag cars can get a high coefficient of friction
is because they put down fresh hot rubber on the track during their burnout
(it's not just for show, it is required). They then back up and line the
car up with those fresh rubber tracks. This results in hot sticky rubber to
hot sticky rubber contact which results in a very coefficient of friction.
That additional traction advantage continues down the entire pass, not just
at the starting line.
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Re: [EVDL] EVLN: Venturi, OSU VBB-3 Electric Racer targets 372mph record 0-60mph:2s

[Bill Dube via EV]

Ordinary pavement in contact with rubber tires give a coefficient of 
friction of about 1. There is no getting around this. It limits the 
acceleration to about 1 g, which translates to a 0 to 60 mph time of 
about 2.7 to 2.8 seconds. To quote the BMW owners manual on the subject 
of traction control: "The laws of physics cannot be repealed".


On the drag strip, they coat the surface with TrackBite. It is 
essentially contact cement. With a TrackBite coated surface, you can get 
a coefficient of friction of 3, or perhaps a little greater. Thus, on 
the drag strip, you can accelerate with 3 g's and get a 0 to 60 mph time 
that is significantly less than one second.


The "layer of fresh rubber" helps, but that alone won't get you anywhere 
near the traction that TrackBite will. A properly prepped drag strip has 
maximum traction without any tires rolling on it.

There are several reasons that dragsters smoke their tires:
1) It heats the tire compound, and make it adhere to the prepped track 
surface.
2) It removes a thin layer of aged hard rubber, and reveals fresh soft 
sticky rubber.
3) It heats the track (slightly). This is of little consequence these 
days. They have cooling coils under the track in the best drag strips to 
hold the track surface at the ideal temperature.

4) It creates a spectacle for the crowd.

I should note that there are other tricks that drag racers use to help 
get traction. They use the rotational inertia of the vehicle to "plant" 
the rear tires during the launch sequence. They use the thrust of the 
upwardly pointed exhaust to give down force. Further down the track, 
they use wings. etc. to give many times the vehicle weight in down force 
to help traction.


Bill D.


On 2/11/2016 9:30 AM, Jack Wendel wrote:


I though I heard of sub 3 second time reported, not theorized.


I recently read of a car that does 0 - 60 in 2.2 seconds. Tesla is FAR 
from optimum.



I have never gotten an explanation I could understand of how
C_friction can
exceed 1 as I have heard regarding dragsters.


I'm not sure why you would assume 1.0 is the mas coefficient of 
friction possible.  Just aluminum to aluminum can be as high as 1.35.



  Friction Coefficients for some Common Materials and Materials
  Combinations

Materials and Material Combinations Static Frictional Coefficient
- /μ_s -_
/
Clean and Dry Surfaces  Lubricated and Greasy Surfaces
AluminumAluminum1.05 - 1.35 0.3

 http://www.engineeringtoolbox.com/friction-coefficients-d_778.html 



The reason high horsepower drag cars can get a high coefficient of 
friction is because they put down fresh hot rubber on the track during 
their burnout (it's not just for show, it is required). They then back 
up and line the car up with those fresh rubber tracks. This results in 
hot sticky rubber to hot sticky rubber contact which results in a very 
coefficient of friction. That additional traction advantage continues 
down the entire pass, not just at the starting line.


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Re: [EVDL] EVLN: Venturi, OSU VBB-3 Electric Racer targets 372mph record 0-60mph:2s

[Jack Wendel via EV]

>
> The "layer of fresh rubber" helps, but that alone won't get you anywhere
> near the traction that TrackBite will.


Nor will TrackBite alone get you there without heating the tires and doing
the burnout. Both are required with a car producing 1000 horsepower or
more.


> A properly prepped drag strip has maximum traction without any tires
> rolling on it.
> There are several reasons that dragsters smoke their tires:
> 1) It heats the tire compound, and make it adhere to the prepped track
> surface.
>

The ideal is when  the track and tire are both at the optimum temperature.
The tires must be heated past the optimum traction point so that they cool
to the optimum temperate at launch. But excessive heating is bad as well.
There is a huge variety of tire compounds available and a lot depends on
the specific tire compound used. You can pick up barely used drag racing
slicks cheap because that compound didn't work for their car.Unfortunately,
it takes a bunch of trial and error to find the right compound.


> 2) It removes a thin layer of aged hard rubber, and reveals fresh soft
> sticky rubber.
>

If it removes a layer of rubber wouldn't that also remove the TrackBite?


> I should note that there are other tricks that drag racers use to help get
> traction. They use the rotational inertia of the vehicle to "plant" the
> rear tires during the launch sequence. They use the thrust of the upwardly
> pointed exhaust to give down force. Further down the track, they use wings.
> etc. to give many times the vehicle weight in down force to help traction.
>

The suspension geometry is also tuned to provide the optimum downward force
at launch. Both too much downward force and too little downward force are
detrimental.
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Re: [EVDL] EVLN: Venturi, OSU VBB-3 Electric Racer targets 372mph record 0-60mph:2s

[Bill Dube via EV]

The reason that Tesla is limited to a 0 to 60 mph of 3.2 seconds is that 
you can only get about 1 g of acceleration on the street. The 
coefficient of friction (on regular pavement) is a little less than one. 
I'm guessing that the 2 second 0 to 60 mph time is calculated using a 
simplistic formula based on 3000 HP and 8000 lbs, and not actually 
measured.


Zero to 60 mph in 2 seconds would be 1.36 g's, which would mean 
that the coefficient of friction (traction) would have to be 1.36 or 
greater. You only get that much traction on the drag strip or on 
specially prepped pavement.


Bill D.


On 2/10/2016 1:12 AM, brucedp5 via EV wrote:


http://www.dailymail.co.uk/sciencetech/article-3434446/Forget-Tesla-s-insane-mode-electric-bullet-car-set-reach-370mph.html
Forget Tesla's insane mode: Electric 'bullet car' set to reach 370mph in
latest record-breaking attempt
5 February 2016  CHEYENNE MACDONALD

[image
http://i.dailymail.co.uk/i/pix/2016/02/06/00/30EC496E0578-0-image-a-65_1454718638153.jpg
This vehicle is the most powerful electric car in the world, and can hit
speeds as high as 372 miles-per-hour. The team is hoping to take it for a
record-breaking run this summer

http://i.dailymail.co.uk/i/pix/2016/02/06/00/30EC497A0578-0-image-a-64_1454718638009.jpg
Student engineers at the Ohio State University's Center for Automotive
Research (CAR) have examined every part of the 12-meter electric car,
including an expanse of cables that totals nearly 3.5 miles. It is 12 meters
long, and contains 2,000 cells within eight battery packs
]

At Utah's Bonneville Salt Flats, a new arrival is gearing up to break
records on the legendary speedway

VBB-3 is latest model by Venturi Automobiles and Ohio State engineers, who
set 307mph land record in 2010

Electric vehicle has 3,000 horsepower, and will try to become world's
fastest car by hitting speeds of 372 mph

Inside, the 12-meter car has cables that total 3.5 miles, and contains 2,000
cells inside of eight battery packs

The VBB-3 is the collaborative project of Venturi Automobiles and student
engineers at Ohio State University, and it boasts nearly 3,000 horsepower.

This vehicle is the most powerful electric car in the world, and can hit
speeds as high as 372 miles-per-hour. The team is hoping to take it for a
record-breaking run this summer.

It can go from 0 to 60 in just two seconds. This compares to Tesla's 'Insane
Mode' on its Model S electric cars that goes from 0 to 60 in 3.2 seconds.

At Utah's Bonneville Salt Flats, a new arrival is gearing up to break
records on the legendary speedway. The VBB-3 is the collaborative project of
Venturi Automobiles and student engineers at Ohio State University, and it
boasts nearly 3,000 horsepower ...

In 2010, the Venturi team set a world landspeed record with an earlier
model, the [VBB-2.5], reaching 307 mph.
[© dailymail.co.uk]



[dated]
http://electric-vehicle-discussion-list.413529.n4.nabble.com/EVLN-Venturi-Antarctica-5seat-EV-for-clean-samples-r-20km-20kph-tp4675020.html
EVLN: Venturi Antarctica 5seat EV for clean samples r:20km@20kph
Apr 20, 2015
...
http://electric-vehicle-discussion-list.413529.n4.nabble.com/EVLN-Venturi-VBB-3-is-world-s-most-powerful-EV-with-3000hp-motor-tp4665585.html
EVLN: Venturi VBB-3 is world's most powerful EV with 3000hp motor
Oct 05, 2013




For EVLN EV-newswire posts use:
http://evdl.org/evln/


{brucedp.150m.com}

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