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Old 09-14-2013, 04:17 PM   #36 (permalink)
aerohead
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Road Load Curve

Quote:
Originally Posted by Tesla View Post
So your improvement with bicycle fairing then provides you with a basis for a hypothesis that you can test a similar improvement on your car.
The ongoing bicycle analogies do not provide any evidence for improved aero at those speeds on a motor vehicle, they merely suggest a corrolation which forms the basis of a hypothesis that needs to be tested on said vehicle.

I formed a hypothesis on the basis of information gathered, much from this site, that the addition of wheel covers, air dam and a few other mods I should see close to 10% improvement in my FE, well it didn't show zip.

Does this mean that aero is a waste of time, no I don't think so, but what it does suggest to me is that it is a lot more complex and just because it improves FE in one persons situation doesn't mean it will do the same for everyone else.
I don't have all the equipment at my disposal to determine how these mods are modifying flow around my vehicle I can only propose ideas to the best of my knowledge and then test them with the rough cut tools at my disposal.
In some cases it may merely be that my testing is not sensitive enough in others it may well be that an improvement in one area may be negated by altered flow elswhere.

As said earlier, I'm not fully convinced that it's as simple as CdA when one gets into the lower speed ranges, but I'm still actively searching and reading to try to understand better what is really going on.

In all this, I always have Aerohead in the back of my mind saying fix the rear then look at the rest, wish I could but a boattail or even Kammback is not really feasable ATM for my vehicle.
On GOOGLE,at 'Development of aerodynamics for a solar race car', by Ozawa et al.,HONDA Research & Development Co.,Ltd.,they offer a Road Load power curve for both their solar racer and a 'conventional' car (read Honda Accord).
I enlarged the table to 11" X 17".At any velocity you can just pick off the aero or rolling resistance road load component.
It's an easy way to see what aero is doing at the lower velocities.And it's prima facie evidence.No Unicorn-Corral stuff.Worth a look.
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