[Frank Lee]

Originally Posted by donee

Hi Metro,

Take a look at the side-profile of a 3 rd Gen Prius, versus the streamlining template, and a 2nd Gen. The 3rd Gen looks like a 2nd Gen backwards. The 3rd Gen looks like the streamlining template backwards in side profile.

The Prius is not like other cars. Above the radiator level the surfaces are not blunt, but sloped. In other cars, these surfaces are horizontal up to the windshield. The 3rd Gen takes this even further, where the front slope is longer than the rear slope, not reaching a peak till behind the front seat. Remember, I have one of these out on my driveway.

And I used to have a 2nd Gen out on my driveway. Which was rather blunt up front, except for the windshield. And it had a long slope from above the drivers head down to the rear spoiler.

I started asking myself these questions when I was trying to figure out how they got all the under-hood space in the 3rd Gen. The 2nd Gen is really packed in there, the 3rd Gen, even with the bigger engine has lots and lots of space under the hood. Where did all that room come from? From the long front taper the 3rd Gen has.

Having a long slope , the air does not shear away over the top like the streamlining template would cause.

I guess you gotta ask yourself if you take a boatail car and run it backwards, if it would have less drag. Because that is what the 3rd Gen Prius is.

As far as further testing goes, well, the weather and other considerations are not permitting me at this time. Water patterns are commonly used to check aerodynamic device effects, and I have commented on those for the initial device.

I am running a .035" thick tubulator behind the peak height right now. It seems to give a 1 mph advantage repeatedly on the downhill test. I have had 2 runs at it so far. One warm with negligable wind, one cool with broadside 15 mph wind. This is a far cry from the 2nd Gen Prius on the same downhill.

Now device I ran originally, probably was acting like a deturbulator, as there were not many spikes, and it was wide. Apparently sail-plane pilots are experimenting with straight tapes applied close to the front of the wing, with reported benefit, as well.

Without tuft tests or a video clip of a wind tunnel test, you don't know for sure what the air is doing up there.

Although I will say- through conjecture- that since the Cd of the Gen 3 is actually better than that of the Gen 2 (AND better than most every other car on the road) that neither version is suffering from some glaring aerodynamic fault.