Aerodynamic Streamlining Template: Part-C - Page 10 - Fuel Economy, Hypermiling, EcoModding News and Forum

AeroModder · 02-12-2011, 01:37 PM

I've had my mind on turning my Tempo into a secondary car for a bit now, and I have my heart set on finding a Civic VX. I've found a few here and there, but I never have the cash on hand.

Tax returns are coming in at the end of the month, and it looks like it'll be enough to buy the next one I find!

I laid the template over the EG hatch, and found it has the perfect roofline already.

As you can tell, I plan on adding a kammback to it, and making the rear end a vertical square surface.

I'll start a thread on it when I finally get one.

Frank Lee · 02-12-2011, 02:29 PM

I might be off-base with this, but to my eye it appears the template's curve is getting a little funky?

BamZipPow · 02-12-2011, 04:24 PM

Quote:

Originally Posted by Frank Lee

I might be off-base with this, but to my eye it appears the template's curve is getting a little funky?

As precise as I can git to tracing things...it's the best I can do at the moment. Perhaps you would like to check my work...I'll be happy to send you my OpenOffice Draw file...

That's why I included this piccie, too!

Frank Lee · 02-12-2011, 06:45 PM

I mean, even on the first one with the teardrop car. It's not a "mathematically smooth" curve to my eye.

It's not identical to this one, which does look smooth to me:

cfg83 · 02-13-2011, 12:35 AM

Frank -

I did an overlay :

NOTE: My image may be incorrect if my choice for "apex/center of camber" is incorrect.

The (very) thin red line is the latest overlay we are looking at. The thicker green line is another overlay base on this image :

The 9.0 degrees is an interpretation of the red and green lines. The 12.7 degrees is the slope of the "shadow" over the EV-1. The EV-1 "shadow" is closer to a straight line from the apex, while the other slopes are more more curved (I hope that makes sense).

Base on the slopes I am seeing, I am going to split the difference and say that the "goal" should be an angle of close to 11 degrees (at least for the EV-1).

CarloSW2

RobertSmalls · 02-13-2011, 09:11 AM

cfg,

I believe you should be ignoring the bottom of the thick green line and using only the top of that line. That would bring the three curves closer into agreement as well.

The goal should be a compound curvature, with no discontinuities in the first or second derivatives ("smooth"). If BZP's green tracing joined multiple splines (or worse, lines) with verticies, that would explain why it "looks off".

cfg83 · 02-13-2011, 04:17 PM

RobertSmalls -

Ok, here's the revised version, and I agree that they are very similar :

Even though I have been using the thick overlay incorrectly in previous posts, I think the inside/outside of the thick line is "close" enough and I feel I needed to see the vehicle for easier mod-visualization.

With that said, I will probably switch to this one :

It is now a 16-color gif with only black and white being used. This makes it easy to do transparent overlays. The above image is at 780 pixels for fitting into an ecomodder album, but I will attach a non-downsized image in a subsequent post.

CarloSW2