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Old 05-11-2018, 06:00 PM   #21 (permalink)
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This is a modification to the car body itself, but it's the shape you want.)
Yes, I know it's not the profile the tool has. I doubled the drop off curve to keep the tail short, and put the same profile on the bottom.
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If you boat tail from inside to inside of the tail lights it saves a lot of fiddling with wiring & etc., but it induces separation before the boat tail. So put wickerbills or Gurney flaps at the leading edge of the taillights to wrap the airflow around.
I was thinking of clear plexiglas covering the car's tail lights in the same angle as the boat tail, so the lights would show through. The lights at the tip of the tail need not be turn or brake lights, but just rearmost running lights and license plate lights, if the Prius' regular brake/stop/turn signal lights can be seen. Of course, access to the hatch is by sliding the boat tail out of the receiver far enough for the hatch to be opened.

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Last edited by Angel And The Wolf; 05-13-2018 at 04:20 AM..
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Old 05-13-2018, 03:21 AM   #22 (permalink)
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See changes above: With the Prius' taillights visible through the clear parts of the boat tail, I may be able to get by with red reflectors and a license plate light on the tip.
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Old 05-13-2018, 08:22 AM   #23 (permalink)
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Quote:
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If you boat tail from inside to inside of the tail lights it saves a lot of fiddling with wiring & etc., but it induces separation before the boat tail. So put [chevron-shaped] wickerbills or Gurney flaps at the leading edge of the taillights to wrap the airflow around.
After driving through a snowstorm in Pennsylvania, the salt spray patterns on my tail were illustrative of where there was attached airflow and where separation; the cut-outs near the lights were covered in salt, but two-thirds of the way back were clean, indicating flow reattachment.

You'll be giving up some energy in forming that recirculating vortex behind the taillights, but not enough that I'd bother with vortex traps.

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Old 05-13-2018, 10:11 AM   #24 (permalink)
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THANKS! Where did you get that tail? Almost exactly what I'm planning. Did you get improved MPG?
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Old 05-13-2018, 11:06 AM   #25 (permalink)
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http://ecomodder.com/forum/showthrea...ead-28466.html

He made it himself.

The big difference will be having the tail slide on it's mount. Do you have a plan for that?
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Old 05-13-2018, 11:36 AM   #26 (permalink)
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He made it himself.
IMPRESSIVE!

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The big difference will be having the tail slide on it's mount. Do you have a plan for that?
Yes, I hope to be able to have room forward of the receiver to slide the mount itself though, and have the mount and tail stay in the receiver when pulled back away from the hatch lid.
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Old 05-13-2018, 01:57 PM   #27 (permalink)
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That's pulled back quite a lot. 24"?

To my eye, it's high-tailed. The air under the car is different than the free flow over the top. Best practice seems to be a diffuser with fencing and cross-fencing.

But since you favor that profile, why not just have it hinge and drop by the departure angle on level ground. My guess would be maybe 18" to clear the hatch's arc.
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Old 05-13-2018, 04:50 PM   #28 (permalink)
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I only favor a lower profile that will clear the road when going up a steep driveway, or deep dip. The angle may not need to be so abrupt, but I have scraped my Receiver before.I think you are close at 18". Maybe even 12 ". My drawing pulls back way more than needed. I did check forward of the receiver, and it is clear for the tail mount bar to stick through at least a foot without hitting anything under the car. The tail mount bar will be removable, I only plan to use the tail for long highway trips, and I feel a latch and hinge is not as safe as a pin secured mounting bar.
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Old 05-13-2018, 10:25 PM   #29 (permalink)
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If I can fit a Diffuser under without scraping.....
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Old 05-14-2018, 01:15 AM   #30 (permalink)
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Telescopic drawer slides come in big sizes. And you could use three.

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