MetroMPG's Honda Insight boat tail extension (cardboard) tuft video; ABA test +9.7%

[3-Wheeler]

Originally Posted by MetroMPG

Can you answer me a question -- how wide is your tail's "transom" / rear surface? EDIT: never mind - found the answer in your tail thread.

Darin,

Sorry for the long delay getting back to you.

I just measured it, and it's 30.25 inches wide.

_______

I suspect that my tail sides slope in too quickly as well, based on your tuft testing.

Hope this helps, Jim.

[MetroMPG]

That does help, thanks.

It's further confirmation that my quick 'n' dirty "eyeball" approach got way too aggressive with the side curvature.

My tail extends 31 inches past the bumper, compared to your 38 inches. Yet my transom width is just 28.75 in., compared to your 30.25 in.! If I followed your curvature, my transom would be wider than yours, of course.

The "final" side angle at the end of my tail is close to 24 degrees. I am genuinely surprised that the flow near the end isn't actually worse than the tuft testing showed.

Too bad, because I really like the looks of that curve!

[silverinsight2]

My friend saw this crazy fiberglass boat tail today in San Francisco - Insight Central: Honda Insight Forum



Yep it's a threewheeler.

[Flakbadger]

So I know this is just a cardboard tail, but it is a work of friggin' art. It complements the lines of the car so well! I vote that you make it into a mold, and fiberglass that thing.

Nice video, by the way.

[Xist]

Originally Posted by Flakbadger

So I know this is just a cardboard tail, but it is a work of friggin' art. It complements the lines of the car so well! I vote that you make it into a mold, and fiberglass that thing.

I would love for others to be able to have their own boat tails, based on all of your hard work.

[Xist]

Fiberglass it and paint it... cardboard brown!

[jime57]

Originally Posted by MetroMPG

That does help, thanks.

It's further confirmation that my quick 'n' dirty "eyeball" approach got way too aggressive with the side curvature.

I'm not sure I'd agree that your angles are too aggressive. The tufts seem well behaved. Most of these early calculations have incorporated some assumptions which may have been slightly overly conservative.

On a slightly different note, have you done an underbelly at the back of the car? Do you plan to do tufts along the bottom of the boattail?

[Xist]

Since you have concern with scraping the bottom and since you are effectively raising your bumper, in a collision their bumper might go under yours, would you consider putting a big scuff pad across the bottom?

How much is Teflon?

[freebeard]

More expensive than cardboard?

[Xist]

Originally Posted by freebeard

More expensive than cardboard?

How much is his time worth?