Overlaying a Car On the Template
 

What do you have to do in order to overlay a car on the template? I am not as computer savvy as I need to be. Or do you request a particular car to be done?:confused:

?
 

I'm not computer savvy either.
I photo-enlarged the 'Template' in a copy machine up to a scale where the max camber point height is 82mm,on 11"X17" paper.
I'll take the subject car photograph to the same copy machine and scale it up also to 82mm in height.
I have a light table on which I can register the two images together,or just carefully place them,and then use Post-Its or drafting masking tape to hold.
By pushing a stainless steel push-pin through the 'Template' and into the photo below I end up with a series of holes which I can connect with a French-curve drafting instrument to draw out the contour.
After this,additional photo-enlargements can be made if you like for greater resolution when measuring angles or dimensions.
It's low tech but will get you in the hunt.;)

You could download this: GIMP - for Windows and read the tutorials or do like I did and ask a twelve year old to do it for you. :o

cleanspeed1 -

I couldn't find a 1990 Accord picture, but I did find a 1993 Seville :

http://ecomodder.com/forum/member-cf...le-overlay.jpg

I am not sure about the center of max roof camber (the first vertical line on the front window), so I hope others chime in. If it is correct, it seems like you could have a small spoiler on the rear to help the aero.

CarloSW2

Thanks for the responses. This may sound odd, but I wanted to see how a 1985 Buick Riviera would look on the template.

Here's a fourth gen Accord. When searching for blueprints it helps to use the chassis code (CB in this case), which can be found on Wikipedia. http://carblueprints.info/blueprints...d_cb3_1989.png

In Photoshop, put the template on a layer above the car and in the Layers tab in the drop down menu change "normal" to "multiply". This will essentially remove all white tints from the image, making it see-through.

http://i44.tinypic.com/2mm5zzc.jpg

If you print this out large it would be very easy to scale it up to full size with some drafting tools, since it includes dimensions :)

Oh, and that Riv blueprint may not exist online so here is one from a photo. It's okay... I wouldn't be surprised if there were no separation on the roof.

http://i41.tinypic.com/2cosr5g.jpg

See, that's why I like this forum. Thank you for doing that.

Here be my version. I use Micrisoft Word, I use the Insert Shapes & Insert Picture functions, then save it as a PDF (I have Acrobat), then save that as a JPG. It is a little complicated but it took about 7 minutes to make this & edit it. I load it into Tinypic.com then link to it here because the ecomodder web page is a pain to load images onto, but it links to stuff great.

http://i41.tinypic.com/do12th.jpg

The template needs to go further back on the Seville; when some of the roof pokes through the template, that's not allowed.

Frank -

I think that's not true. For my wagon the roof pokes through the template because it *violates* the ideal shape :

http://ecomodder.com/forum/member-cf...te-overlay.jpg

But I could easily have the center of max camber wrong. When I slide it back it looks great :

http://ecomodder.com/forum/member-cf...oof-camber.jpg

CarloSW2

Cleanspeed- glad to help.

Frank and Carlos-
It's probably better to line it up to the rear of the roof in the case of the wagon just to get smooth flow. But in general...
http://gawker.com/assets/resources/2...itpicking.jpeg

In #10 the wagon roof poking through means the template needs to go rearward until it doesn't. The Seville looks good now- that's what I'd use on that one. :thumbup:

Frank -

I used to slide the template back until aerohead corrected me :

In the above, the center of max roof camber is more important than aligning the end of the car to the template.

I asked the same question here :

http://ecomodder.com/forum/showthrea...ber-12801.html

CarloSW2

http://ecomodder.com/forum/showthrea...-c-9287-8.html

http://ecomodder.com/forum/showthrea...-c-9287-9.html

I know, my RanchAero overlay isn't on there right. I believe I used Picasa and when I clicked on the overlay it went see-through, so I took a screenshot [Ctrl + Prt Scr].

And I was thinking an "Overlay the aerodynamic streamlining template" thread would be good.

Not buying it. I think having the roof poke through the template aft of max camber renders flow downstream of the poke-through compromised and thus the whole project moot. Were those guys thinking of cutting the roof down, not simply adding the Kamm aft of what's there? Were I to do a template overlay on Moon Unit I'd first scale the heights then slide the template aft until there's nothing pokey outey.

I used a combination of Microsoft Word, the online application pixlr, very basic html coding, and Microsoft Paint for my overlays. Basically, I rotated the vehicle image until it was horizontal (the image was originally rotated about 0.8 degrees). I then performed a transparency operation on my vehicle image using pixlr to make the background transparent. I then used html code to match the sizes of the vehicle and the aero template, as well as matching the 0 degree point of the aero template to the vehicle top as described. After I was satisfied with the result, I pressed <alt>-<prtscrn> to grab the picture as a screen capture, then pasted it into Microsoft paint to save the capture as a PNG image.

This is the result:

http://www.tom-viki.com/spgm/gal/Car...akota_aero.png

Frank -

I hope you're right because that means my wagon is good "as is".

CarloSW2

Your wagon is good as is, but would be better with a kamm tail extension! :thumbup:

Template is optimal shape, but it is for best length of 'wing', there are longer wings with different aspect ratio, different kind of aerofoils, maybe longer vehicle would require template to be adapted for such?

My roof is one big level plane, so highest point is almost everywhere, but then again having really good pic from side is something difficult, if car is not photographed directly from the side and from appropriate height there will be big errors, also blueprints are something one really can't trust, those can be way off, but can of course give some idea from shape. There is many things to consider.

Chopping rear end of wagon would make quite nice mini kamm though :P

"Blueprints can be way off"? It's pretty easy to judge the good ones vs. bad ones.

But I agree with what you're saying about the template. Since the wagon's roof is so flat you can probably stretch the rules a little to put the 0% mark near to the rear of the roof. It will give a better overall flow than pretending you can cut off a chunk of the rear to fit the template.

So is the goal to make vehicle conform totally to the template shape? Some of the body shapes require a boattail that goes waaaaaaayyyy back, and may not be everyday practical or aesthetically pleasing.

I am an aero virgin, please be gentle.:p

This is what happens when you play with engines for the better part of your life.

Depends on what you want to use the vehicle for, and how much cutting and hacking you are up for.

I mean for maximum effect, the cutting and hacking is just the price of admission.

For maximum effect, you must of course go with maximum shape, ahem full shape that is.

However most of the effect comes from first part, there was recent thread about that also, can't remember how much it was, but it was not much that you would need to get most of the effect.

I have now 50cm kamm behind my wagon, that is bit under 2 foot as 66cm is 2 foot from my memory.

Even it is no larger than that, it still seem to be very efficient as coast down testing did show 24% improvement for air resistance, but there is some error margin, so I like to think it being 'only' 18% of improvement.

I think that is really a lot, but it coasts down really well and even wind noise is lot less, so I'm thinking that it must be true that first parts of template makes most effect.

So that we are clear, you are talking about the front of the template vehicle, correct?

NO!!! First part of boattail as used on a kamm.

This is exactly right.

Front part is not meaningless, but it is rather not important, always focus the rear and there is most of the gains.

Sure there are few things at front too, but most is rear and maybe underside, rest I would leave for when one would like to get even more, but that is just my idea of aero.

OK, got it.

Haven't had coffee yet, Frank?;)

Haven't been to sleep yet. :mad: Terrible insomnia.

Ha, I know that feeling, but it's involuntary... working on homework :(

Clean, if you go out to about an 80% boat tail it will form enough of a "phantom boat tail" as to make the last 20% superfluous. In short, don't bother with the last 20% because the air will take care of it anyway. % points from the top of roof camber (0%) to the very rear tip of the template (100%).

practical
 

Kamm,Korff,and others were pushing the concept of enough tail such that the wake area would be only 50% of the vehicles frontal area.
Kamm toyed with inflatable tails to make up the difference when away from city hazards.He was not unaware of the aero benefit of a full boat tail,but certainly realized what parking and driveways and pedestrians might be like to negotiate within the city.
You just need to weigh out your own needs and what you think you can live with.