Best teardrop shape proportions for low aero drag?

[Big time]

A raindrop is too general a shape.
Can be too short and wide i.e. those like this
Page 2 The Xara Xone Workbook - Creating Drops of Water

So, What is are the best proportions for aerodynamic purposes?

Are there raindrop proportions better for Kammback use?

[ChazInMT]

Uh...welcome to ecomodder. Have you looked into the exhaustively discussed aero template in here?

Check it out THIS discussion and it will answer all your questions...get comfortable.

[freebeard]

...or you could search on 'fineness ratio', which describes the number you are looking for.

Essentially 2.5—>4.

[kach22i]

Originally Posted by freebeard

...or you could search on 'fineness ratio', which describes the number you are looking for.

Essentially 2.5—>4.

Yep, from what I recall the aero-shape ratio of width to length of free air verses close proximity to the ground goes from roughly a 1:3 ratio to 1:5 ratio respectively.

Read up on that thread ChazInMT posted, it's a good one.

[aerohead]

Let's see if I can get something over from Photo-Bucket
You can see the fineness ratio with the lowest Cd.
Hucho puts it at 2.5:1,and in mirror-image ground reflection creates a vehicle body with an 'effective' length-to-height ratio of 5:1 and Cd 0.08.
By adding wheels the Cd goes up to 0.12-0.13.
Wheel fairings can bring that down as with the 1987 GM Sunraycer/1993 HONDA Dream 2.
This is the premise for the Aerodynamic Streamlining Template.

[Xist]

I think that I saw that before. I guess that "filling the wake" still helps, even if we do not maintain attached flow.

[aerohead]

Originally Posted by Xist

I think that I saw that before. I guess that "filling the wake" still helps, even if we do not maintain attached flow.

Yes,it looks like even a compromised aft-body will still provide some drag reducing potential as with Chrysler's experiments with their De Soto Airflow test mule demonstrated.
Their 'fast' rearend helped get the Cd 0.51 of the orig. car down to Cd 0.244.
Not too shabby for 1934!

[freebeard]

[Big time]

Thanks a lot guys.

I've never heard of the fineness ratio until now.
A great concept to dig into.

That's why Ecomodder rocks!