cem:
ANY OBSERVATION WITHOUT MEASUREMENT IS NOTHING..
also a test without measurement is not a test.. but when you start to measure now we can start talking..
Lazydocker:
Because, in your own words, you are an engineer
Cem:
Here are some definitions and questions explaining why I said that..
The word measurement is derived from the Greek word "metron," which means a limited proportion
Why do we measure ?
In science, measurement is the process of estimating or determining the
magnitude of a quantity, such as length or mass, relative to a unit of measurement,
such as a meter or a kilogram.The term measurement can also be used to refer to a
specific result obtained from the measurement process.
for science we need standardization, we revere precision, and we aspire for control. The very
ancient and dominant belief of Western culture is that numbers are what is real.
If you can number it, you make it real. Once made real, it's yours to manage and control.
We depend on numbers to know how we are doing for virtually everything.
It is numbers and only numbers that define and make visible what is real.
This is the "hard stuff," the real world of management- graphs, charts, indices, ratios.
Everyone knows that "you can only manage what you can measure.
Lazydocker:
So you cannot accept different weights mean different performance? Why?
As an engineer you must know that momentum is related to the mass in motion.
Therefore a 1000Kg car cannot possibly have the same momentum as a 2000Kg car
travelling at the same speed That additional momentum (and mass) can and does
make a huge difference to how a tyre will perform
Cem:
tyre performance is barely the grip between the road and tyre which is a function of friction
coefficient changing from tyre to tyre that you try to compare with tests..
if friction coefficient is 0 there will be no grip at all..
momentum has nothing to do with friction between your tyre and road.
momentum is mass * velocity, so kg * m/s
friction coefficient is dimensionless either kinetic or static..
friction force is kg * m/s2
so apples and pears really..
Cem:
most of daily passenger cars start around 1000 kg and go upwards .. most using MacPherson
type struts and there is no hocus pocus in this area.. so whatever your cars weight is,
the results although changing in magnitude , the relative measurement test orders will never change totally..
Lazydocker:
most of daily passenger cars start around 1000 kg and go upwards .. most using MacPherson type
struts and there is no hocus pocus in this area.. so whatever your cars weight is, the results
although changing in magnitude , the relative measurement test orders will never change totally..
Actually, a lot of "premium" cars are now using double wishbone set up instead of MacPhearson
struts because MacPhearson Strut set up is flawed and poor performing in a heavy car...
So even if tyre tests were done on a large premium car they would still only have limited relevance
Cem:
now to simplify the picture take any of the tests alone (because they are a combination of
different tests) ,braking ,lateral grip or road resistance .. it varies from tyre to tyre by
friction coefficient difference in any case..although tyres dont behave like a brick it doesnt
change the result because you measure the already effected final coefficient of friction.
and different tyres will sort themselves within the test relational to their friction
coefficients..the only problem here is that tyre producers.. will they keep their expensive
compound and structure with increasing sizes or not ? unfortunately answer wont be yes all the time..
from wikipoedia
"The double wishbone suspension was introduced in the 1930s. French carmaker Citroën used it since 1934
in their Rosalie and Traction Avant models. Packard Motor Car Company of Detroit, Michigan used it on the
Packard One-Twenty from 1935. and advertised it as a safety feature. Prior to the dominance of front
wheel drive in the 1980s, many everyday cars used double wishbone front-suspension systems,
or a variation on it. Since that time, the MacPherson strut has become almost ubiquitous, as it
is simpler and cheaper to manufacture. In most cases, a MacPherson strut requires less space to
engineer into a chassis design, and in front-wheel-drive layouts, can allow for more room in the
engine bay. A good example of this is observed in the Honda Civic, which changed its front-suspension
design from a double wishbone to a MacPherson strut after the year 2000 model.Double wishbones are usually
considered to have superior dynamic characteristics as well as load-handling capabilities, and are still
found on higher performance vehicles. Examples of makes in which double wishbones can be found
include Alfa Romeo, Honda and Mercedes-Benz. Short long arms suspension, a type of double wishbone
suspension, is very common on front suspensions for medium-to-large cars such as the Honda Accord
(replaced by MacPherson struts in 2013+ models), Peugeot 407, or Mazda 6/Atenza, and is very common
on sports cars and racing cars.It also provide least camber change at bump and rebound condition."
its not new.. as said because of space and cost limitations its not commonly preferred.
we are talking about omegas which have standard macpherson struts.. where many other cars use the same..
all tyre test makers note which car they used in tests so you can be aware if you want to omit.
However I dont change my opinion and I still think test results meaningful as they
test all tyres in the same double wishbone.. so test order wont change and results are still relevant ..
Author
Topic: a tyre discussion .. (Read 1150 times)