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呃~基本上市售車不太可能有過彎側向1.8g的表現



https://i.imgur.com/NTrmReu.jpg

主要由四顆輪子的側向力提供車輛過彎時所需的向心力

當然會因為輪胎側滑角(tire slip angle)

所以實際提供的向心力會是四顆輪子乘上該輪側滑角的分量總和



1.8g過彎，代表向心力是車重的1.8倍

假設以最理想的四輪重量平均分配的條件，那輪胎的側向摩擦係數要有1.8

一般市售車配胎，側向摩擦係數約略0.8~0.9左右

就算是頂級街胎，側向摩擦係數了不起就是1.2~1.4左右(也許我還有些高估了)


https://i.imgur.com/Xd0wLY2.jpg
https://i.imgur.com/egWpcvt.jpg

輪胎載重增加，雖然能提供的側向力會增加

但最大摩擦係數會越來越小

也就是若同輪胎下若車重增加，也會不利於過彎表現



https://i.imgur.com/WOsOPjZ.jpg

那為啥像方程式或有些單艙賽車的側向G值可以到2以上

因為除了車重外，還依賴空力提供的下壓力

輪胎vertical load增加，能提供的側向力自然增加



量測到過彎1.8g

很大可能是儀器安裝時並沒有固定穩



最後附上Focus RS從PSS換成Cup2的表現

Ford Focus RS with Michelin Pilot Sport Cup 2 Tires
https://reurl.cc/oDWoM5

The Focus RS comes from the factory on capable Michelin Pilot Super Sport
radials. Like our Lightning Lap car, this example came with a $1990
wheel-and-tire package consisting of a specific 19-inch forged-aluminum wheel
and as racy a tire as you can put on a street car, the Michelin Pilot Sport
Cup 2

Stopping from 70 mph takes 154 feet, which is only four feet shorter than a
Super Sport–shod RS, but lateral acceleration jumps from just below 1.00 g
to 1.04 g

This RS’s accelerative performance—zero to 60 mph in 4.6 seconds and a
13.4-second quarter-mile—is unchanged

70mph下煞停距離：158 feet -> 154 feet
側向加速度： 1.00 g -> 1.04 g
加速性能：不變

從PSS換成Cup2，側向加速度只提升0.04g唷


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