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Old 11-15-2008, 08:17 PM   #44 (permalink)
trebuchet03
MechE
 
Join Date: Dec 2007
Location: Bay Area
Posts: 1,151

The Miata - '01 Mazda MX-5 Miata
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Quote:
Originally Posted by aerohead View Post
Sorry,late to the party.I was looking at some of the "side-by-side"comparisons with the Prius and couldn't see the bottom of the tires very well.What I wanted to share,is that when scaling,it's important to match the height of the cars,as the cars fineness ratio is dependent upon it,and progressive roof curvature without separation,also a function based on height above the ground plane.
My car vs. Prius in reality - are within an inch in height In those pictures, the tires got cut off.... But, it would seem that those images weren't optimal for that sort of comparison (basically, I grabbed the first image that looked somewhat ok).

Quote:
Wow, it changed from a few MB as a DXF to 80mb under Solidworks?

I know the interior bits are superfluous, and could be removed, but... that's a huge change. I remember the old thread where you were having the machine crash loading the model, and I couldn't fathom why. 80mb of data, and then rendering it onscreen, now I can.
I didn't even include the interior features The reason for the increase in size is because SW converted everything into surface features... It's actually a fair bit bigger than 80 at the moment :/

-----
Fresh Batch of Results....

This is a Fusion like model - deck lid was extended to twic the original length and I followed the lines of my trunk










So, is it better than stock?



Can't say... For sure, the wake is longer with the modified deck lid. And the extended lid doesn't seem to change where separation occurs. Is it better? I can't say for sure - but I'm leaning towards no, not for my car.

From CD-adapco's website
Quote:
"Drag reduction of the Ford Fusion Hydrogen 999 was a key element of the successful world record attempt. By taking advantage of CFD analysis, physical test times could be reduced and multiple configurations of the vehicle studied. Other benefits included insights such as adding a rear spoiler for stability. Eventually the drag was reduced from 0.34 to 0.21, helping the Fusion to become the first fuel cell powered car to pass the 200 mph barrier. Partnering with CD-adapco's engineering services, and using its advanced family of STAR software solutions, allowed us to draw from a greater pool of expertise spanning CFD and aerodynamics." John W. Zaleski, Program Manager, Roush Industries.
CD-adapco Press Room - CD-adapco helps Ford design the world’s fastest fuel cell car

Stability obviously means it's doing something aerodynamically.....


In other news - I took a long stick to my car - to see how much would be added to kamm that went from trailing edge of trunk to tangent on roof as seen in a CFD model posted yesterday.... It's not big at all - in fact, it basically extends from the top of my rear glass down to my trunk.

Additionally, I have figured out a taper line that is easiest to manufacture - basically, following the line my trunk seam makes. If all goes well, I'm shooting for a rough prototype next weekend.




Next in the pipe
  • Flat Deck Extension
  • Boudnary Layer Trip
  • Streamlined Foil

Still taking requests.
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