Aerodynamic streamline template - online tool (view streamlined extension on any car)

[Daox]

Both of those images are incorrect. Check the instructions on how to do it. The apex of the roof line should meet the apex of the aero template. You should end up with something between the two images you have.

Something more like this...

[wyatt]

I don't know if it's been discussed (I didn't read all the posts), but how hard would it be to add a "rotate" function for the original image? I guess it would be the same difference to rotate the template, but I think it would be useful seeing as how not all pictures are taken flat, and not all configurations can be recreated.

[seifrob]

It has been considered, but rejected for simplicity and reasons.

Although it is possible (see here: How to Rotate Images Using JavaScript (JavaScript & Canvas). Cross-browser Solution. — ajaxBlender.com), it would complicate the code and won't be much use (you can rotate only in certain steps). Much better solution (from my point of view) is:
a) photograph level pictures
b) Use straighten/level tool that you find in almost any good photo browser/editor. (Google Picasa, IrfanView etc.) - thus you will have straightened picture for future use.

once you have picture with level ground, you can freely use it

[ERTW]

Well, I was matching up the GM Precept with the template. At first glance it looks like it's way off...not even approaching the 50% mark. But how come it's one of the most aerodynamic cars on the planet (Cd = 0.174)...which still looks like a car, can fit four people comfortably, and looks like it can be mass produced? Note that it only uses half wheel covers, and non-dished wheels.

I changed Aerohead's spherical nose to a 1.36:1 ellipsoid two years ago. Far short of the 2.5:1 ellipse that pre-war research shows. Sharks and boxfish have tapered noses. It follows the Precept very closely.

I tried many ellipses at the rear and it didn't conform to any. Next, I lined up the rear half of the template and started shrinking it. The drawing is exactly 1/2 scale. I was surprised, and elated. So the template doesn't just work at full scale. Again, my hat is off to Aerohead

edit: Kachi22i scaled down the template may 24, 2013...but you DON"T scale down your success I believe I know why it works on the Precept, and not so much on the Porsche 911.

[aerohead]

This is what I have for the Precept.Originally,GM claimed Cd 0.163 for this concept.

PS,my image is not in true-length.It's the only thing that I have which is close.

[Xist]

Common procedure around here is to post an incorrect image and then someone else will go through a great deal of effort to fix it for you.

This is what I use: GIMP - Downloads

It is overkill, though, Windows Paint has all of the other features that I really need.

Does anyone know of a simpler program?

[ERTW]

Originally Posted by aerohead

This is what I have for the Precept.Originally,GM claimed Cd 0.163 for this concept.

PS,my image is not in true-length.It's the only thing that I have which is close.

Thanks Aerohead. I see that number quoted most often. I read a web article, and for the life of me I can't find it again. It details the shape development. Iirc the wizards who designed the body only had FOUR hours in the wind tunnel. It started off around 0.15 and it crept up after adding body gaps and such. I recall the .17x figure.

3/4 views look cool. However, three orthographic views allows anyone to create an accurate 3D model. Precept photos are rare, and rarely helpful. I can't even find basic dimensions. I am very eager to look more closely at its shape...

Fwiw mercedes claims that their bionic car can potentially get down to 0.095. Isn't that the ideal land vehicle Cd?

[aerohead]

Originally Posted by ERTW

Thanks Aerohead. I see that number quoted most often. I read a web article, and for the life of me I can't find it again. It details the shape development. Iirc the wizards who designed the body only had FOUR hours in the wind tunnel. It started off around 0.15 and it crept up after adding body gaps and such. I recall the .17x figure.

3/4 views look cool. However, three orthographic views allows anyone to create an accurate 3D model. Precept photos are rare, and rarely helpful. I can't even find basic dimensions. I am very eager to look more closely at its shape...

Fwiw mercedes claims that their bionic car can potentially get down to 0.095. Isn't that the ideal land vehicle Cd?

Hucho has suggested that with extremely careful integration of the wheels,that we might approach the Cd of the basic body of 0.08.

[aardvarcus]

Originally Posted by Xist

Common procedure around here is to post an incorrect image and then someone else will go through a great deal of effort to fix it for you.

This is what I use: GIMP - Downloads

It is overkill, though, Windows Paint has all of the other features that I really need.

Does anyone know of a simpler program?

Microsoft PowerPoint 2010 is what I use. Put the picture of the vehicle and the template on one slide. Scale and rotate the car and/or template to match using the built in tools. The magic is that when you start dragging the pictures, they go half transparent automatically. Drag the photo of the template over the photo of the vehicle. Move it with your cursor till it lines up, then before you let go of the image, hit the print screen button. Paste the screenshot on a new slide or in paint, crop the border, and you are done.

[jray3]

I'd like to build a trailer shell following the template, but with flat panels that are precut to shape, zeppelin-style. Undecided on a riveted aluminum skin vs foam panels to then glass over, or soaking an inflated envelope with resin, then building it up, but am leaning towards aluminum (possibly with a spray-foam interior layer to stiffen and insulate).
So far I've struck out on finding a pattern to scale up. Closest thing is these hot air balloon panels from a crafter's blog (don't laugh if you click through).
http://prudentbaby.com/wp-content/up...ir-balloon.pdf

DIY Hot Air Balloon Mobile (Free Pattern!) | Pretty Prudent

This company gets me close, have requested a design cost estimate....
APEX Balloons - Hot Air Balloon Manufacturer, Hot Air Airships, Balloon Repair Station

Any of you design wizards already cracked this nut?