Boattail on a Prius

[ENERGYprof]

I am building a removable boattail for my Prius.

After some discussion about a removable molded kammback, I have been persuaded by ecomodder users to go for a full boattail instead, and thus the new thread.

1) The departure angle is as low as my driveway will tolerate.
2) The design uses aluminum for a frame, with a 1/4" wall 2" square pipe coming out of the hitch-receptacle, and 1/8" wall 1" square pipe for bracing. Thin-wall aluminum is being used where possible. The pieces are being bolted together, and will later be welded in place for extra strength. The 1/4" wall pipe was welded at an upwards angle, and should serve some safety purpose.
3) To support the coroplast, foam spars are being used, like inside an ultralight airplane, which are glued in place with polyurethane expanding foam.
4) The coroplast will be laid over the spars. Excess foam can be easily shaved down with a wood file for last minute changes.
5) The hatch can still open and be useable.
6) The entire assembly should be quickly removable for a maximum W.A.F. rating*.


I am constructing this in my garage to avoid neighborhood gawking, which hasn't seemed to help. Neighbors have already walked over to get a better look.

After I am done, performance springs will be added for a lower and stiffer ride, and a front air dam may do a better job than my current grille-block.

Any advice will be appreciated!!!!!




*Wife Acceptance Factor

[ENERGYprof]

[ENERGYprof]

I'm going to have to add some lights to this sucker. Its long. Will look sweet with a set of Weld Racing wheel covers and some rear skirts.

[NeilBlanchard]

Hi,

Looks good so far, but can you photograph it outside? Yes, I think lights are a must!

Let the neighbors look -- maybe they will get interested in ecodriving!

[Cd]

Congratulations !
- You are the first one to actually build this idea as a working prototype.
Very interesting.

[Christ]

I feel like the neighbors are going to give some unsolicited feedback... but maybe that's just the "typical american" in me talking.

[ENERGYprof]

Ok, here it is outside in full daylight. Today I laid the coroplast over the spars, and found that I will need much more trimming. Between a razor and a wood file, that part seems to be going pretty quickly. Next step is to continue adding spars and attachment points for the coroplast... and cutting down the spars for less of a beluga shape!


I also spent a few hours cutting down a set of aftermarket springs to drop 'er a little lower to the ground. I tried using a hacksaw,... let me tell you that just plain sucks. Those things are hard! I ended up using a chop saw which went pretty quickly and didn't seem to get the steel very hot. Should drop the front end down 3" and the rear end down about 1.5"... That will leave me some room for taller front tires.

BTW, Here are the wheel covers I've picked out:
Weld Racing Air Flow Wheel Cover System
And here's a nice set of skirts to fit a prius:
Toyota Prius - Wheel Skirts - Toyota Prius Wheel Skirts by Hybrid Effects 1 pair (Shipping Included)

[basjoos]

Looks good so far. The only comment that I can add is that, if you incorporated a steady curve into the boattail, you could make it shorter and still have the air fully attached along its length. One thing also to consider on the longer boattails is how far they will swing out in the opposite direction when making a sharp turn.

Below is the tail of a Questair Venture kitplane which I used as a model for the shortest possible, fully effective boattail shape for my car's boattail.

[ENERGYprof]

Holy frick... I never thought about that big schlong swinging around when I turn a tight corner. Glad you mentioned that! I have a lot of shaping to do on the tail yet. Right now it has no curvature to it, but I can easily add some. I'm going to use Lexan for the top... ultimately I'd like to be able to have my factory rear tag be visible, and factory lights be visible too... if possible. I may have to add some flat bar aluminum that I can bend into brackets to replace a few of the spars on the upper half. Now I just have to figure out how the heck I'm going to park this thing.

[Christ]

Not that I assume you can find it cheaply, but fiber optic cord (if you can find it at length) can transfer the light of the tail lights to any direction you'd like it, and doesn't degrade the light too much.