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Old 03-30-2013, 01:53 PM   #111 (permalink)
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Made a New template with only the rear contour, ground plane, and percentage marks. Fits the other template almost perfectly. Made so scaling this template doesn't move the ground plane and 0% by as much as the old template. Not sure it would be used though.

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Old 03-30-2013, 03:03 PM   #112 (permalink)
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Made a Mirrored Version as well as darkened the percentage lines



Background is transparent so if you click the tiny img, it only shows numbers.
Attached Thumbnails
Click image for larger version

Name:	Aero Template.png
Views:	529
Size:	12.3 KB
ID:	12799   Click image for larger version

Name:	Aero Template2.png
Views:	517
Size:	12.2 KB
ID:	12800  
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Old 03-30-2013, 05:35 PM   #113 (permalink)
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Originally Posted by betasniper View Post
Made a Mirrored Version as well as darkened the percentage lines



Background is transparent so if you click the tiny img, it only shows numbers.
betasniper,thanks for the cleanup! Anyone contemplating a build will have a much better go at it with these 'clean' profiles.
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Old 03-30-2013, 07:23 PM   #114 (permalink)
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yeah, that is why I made them. I believe the online template tool is good already, but I like to try to make things better. They are free for anyone to use for anything. (since I have to say I release the images "copy rights")
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Old 03-31-2013, 09:41 AM   #115 (permalink)
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Interesting stuff betasniper. A question. What steps would one go through to construct a "full size" template for use in boat tail construction?
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Old 03-31-2013, 11:46 AM   #116 (permalink)
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Interesting stuff betasniper. A question. What steps would one go through to construct a "full size" template for use in boat tail construction?
Jim,

See my post at....

http://ecomodder.com/forum/362869-post517.html

There is an equation that predicts the "ideal" tear drop shape.

You can use that equation to work out a full size template for a car tail extension.

Someday, if I ever make another "improved" copy of the tail, I would use this same technique to better adhere to AeroHeads original shape.

Jim.
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Old 04-02-2013, 02:10 PM   #117 (permalink)
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I was actually trying to make good use of my time--sleeping! However, I jumped out of bed at this idea.

For a given body moving through air, does the air itself care the size of the body?

Let's say that we could purchase plastic or fiberglass boat hulls that fit the template perfectly for a Prius. They might be too narrow or wide, but couldn't you cut it down the middle and trim or add spacers?

Now, if that is the ideal taper, what about objects of other sizes? What if you had a big and rounded old bus. I doubt that the corners would fit, but let's say that they do. The shell is too wide, so you cut it down the middle, cut a piece of fiberglass of the correct curve, and attach it. Would you continue at 22°?

If I boat-tailed a go-kart (I bet that you won't dare me to!), would I have the full 0°-22° taper (could I still use part of the theoretical boat tail?) or, since it would be so much shorter (vertically), might I only get to 8°?
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Old 04-03-2013, 06:10 PM   #118 (permalink)
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size

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Originally Posted by Xist View Post
I was actually trying to make good use of my time--sleeping! However, I jumped out of bed at this idea.

For a given body moving through air, does the air itself care the size of the body?

Let's say that we could purchase plastic or fiberglass boat hulls that fit the template perfectly for a Prius. They might be too narrow or wide, but couldn't you cut it down the middle and trim or add spacers?

Now, if that is the ideal taper, what about objects of other sizes? What if you had a big and rounded old bus. I doubt that the corners would fit, but let's say that they do. The shell is too wide, so you cut it down the middle, cut a piece of fiberglass of the correct curve, and attach it. Would you continue at 22°?

If I boat-tailed a go-kart (I bet that you won't dare me to!), would I have the full 0°-22° taper (could I still use part of the theoretical boat tail?) or, since it would be so much shorter (vertically), might I only get to 8°?
As far as size,the air doesn't know the difference (My Fortran IV professor would kill me for saying that).The air velocity must match such that 'dynamic similarity',or,'verisimilitude' exists for the body as far as Reynolds number is concerned.
If you found a boat hull which at the height of the Prius,happened to match the contour of the 'Template' you could use it for an 'ideal' body.And narrowing would be a must.
I've tried this with the full-boat-tailed trailer project.You'd want to find a better 'candidate' boat than the one I used.
The only parameter that's critical is the overall height above the ground where the body will be the tallest.Everything is scaled from there.
So with the go-kart,you'd probably use the top of the rollbar as your 'peak' and go from there.But bear in mind that you've got to have 'clean' air coming at the tail,so the kart would have to be completely enclosed for it to function.
I have a 21-foot sailboat hull which will become a 5th-wheel RV trailer.
If I live long enough to do it.
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Old 04-28-2013, 03:15 AM   #119 (permalink)
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Quote:
Originally Posted by aerohead
And narrowing would be a must.
That being the case, a pie-shaped cut would broaden the range of usable hulls. OTOH, the Template is more like a pontoon.

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Originally Posted by Xist
If I boat-tailed a go-kart (I bet that you won't dare me to!)
I dare you to take two surfing short-boards, mount one on the top of the roll bar, cut the go-karts length out of the other one and fashion front and rear bumpers—and then tension trampoline netting into a hyperbolic paraboloid between the two. It would act like a tinted window, shed rain and the permeability would slow the air but equalize the various high and low pressures on the front, back and sides of a Tromphenwagen shape.

Do you even have a go-kart? It would be the safest one on the block.

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Old 04-28-2013, 04:40 AM   #120 (permalink)
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That being the case, a pie-shaped cut would broaden the range of usable hulls. OTOH, the Template is more like a pontoon.



I dare you to take two surfing short-boards, mount one on the top of the roll bar, cut the go-karts length out of the other one and fashion front and rear bumpers—and then tension trampoline netting into a hyperbolic paraboloid between the two. It would act like a tinted window, shed rain and the permeability would slow the air but equalize the various high and low pressures on the front, back and sides of a Tromphenwagen shape.

Do you even have a go-kart? It would be the safest one on the block.
Here I was worried that nobody would understand my question, but luckily, Aerohead read it! I think that I understood his answer!

I am not sure about yours, though Freebeard. Why don't I just get a bunch of 4'x8' sheets of foamular?

Maybe I could use some kind of windscreen with transparent plastic or glass instead of something from a trampoline.

Tromphenwagen?

Hey, I hear finals calling! Gotta go!

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