Quote:
Originally Posted by Vman455
I came across this in a textbook last winter. It seems relevant here.
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I just saw this, and immediately thought: that must be from about the worst current textbook on car aero. And I was right - 'Theory and Applications of Aerodynamics for Ground Vehicles'.
That para is absolute garbage. To show the 'quality' of this book, note how reference 9, cited in the para, isn't even in the chapter references...
A spoiler, common in sports cars, is a negative lift device.
Yes.
It reduces the lift by slowing down the flow over its upper surface.
What surface? Not the spoiler, as this suggests.
A negative lift wing is the most common type of spoiler.
No, a wing is not a spoiler - how basic a mistake can be made?
When lifting devices are used, it is important to place them in the proper location at the rear of the vehicle, or they may turn out to negate the very effect for which they have been incorporated [9].
Ref 9 not included in chapter references (there are none for the book as a whole). It's highly unlikely that any spoiler will create lift on any modern car (where most lift comes from attached flow), unless something really weird is done so that the spoiler deflects air massively downwards.
For example, a spoiler on the vehicle rear roof only adds to the lift.
I don't think this is the case - in fact I think this is balderdash on any modern car with attached flow over the rear window. But OK, now where is the evidence for this? None is presented.
The book is full of mistakes - staggering that it was published by the SAE. If you want to learn about spoilers/wings/etc, Katz, Hucho or Scheutz are the gold standard - especially when compared to this book!