On Wed, 08 Oct 2008 03:42:58 -0700, Nige Danton wrote:

On Oct 8, 3:35Â*pm, Adrian wrote:
Nige Danton gurgled happily, sounding much like
they were saying:

within any given class are likely to be fairly similar. As a rough
rule of thumb, increasing drag starts to come seriously into play
from about 60mph upwards.
Drag cubes with velocity and so it may become important at speeds
lower than 60 mph.

Trust me on this... I've got plenty of experience with low-powered,
unaerodynamic vehicles. It starts to come into play at about 60.

I'm a cyclist and aerodynamic friction plays a huge role in determining
speed and above ~30kph the benefits of drafting behind another cyclist
are considerable. There's an energy saving of ~20% for the first cyclist
in a pace line and that rises to maximum of ~30% for the fourth cyclist.

I really would be surprised in cars are so slippery that aerodynamic
friction does not play a significant role at speeds slower than 60mph.

What sort of vehicles are you referring to?

IIRC about 20 years ago, 30 mph, was about evens between the air drag and
other resistances (mainly tyres). These days the shapes are more slippery
so 40mph might be the balance point.

It all depends on what you mean by 'significant' and 'dominant'
If 40 mph was the balance between aero drag and other friction then
At 60mph aero drag is about 70% of total which I call significant.



--
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