Project: Geo Metro boat tail prototype - 15% MPG improvement @ 90 kph / 56 mph

[archcritick]

This looks like it has problems for any car that will be a) driven in traffic or b) parked in a parking space.

I wonder if inflatability might be an answer- the thing could inflate and extend at higher speeds, and retract at lower.

Looks like the first stage of cowling could be transparent, solving the visibility problem.

And an excellent crumple zone it is, as someone pointed out.

[Otto]

Originally Posted by archcritick

This looks like it has problems for any car that will be a) driven in traffic or b) parked in a parking space.

I wonder if inflatability might be an answer- the thing could inflate and extend at higher speeds, and retract at lower.

Looks like the first stage of cowling could be transparent, solving the visibility problem.

And an excellent crumple zone it is, as someone pointed out.

Actually, NASA or the US Dept of Transportation studied inflatable bag fairings some years ago, and found the idea to have merit. The thing billows out behind the truck trailer like the shirt on a motorcyclist, so is self-inflating, but then drooped or sagged down at low speed. Perhaps a take-up reel could be used to retract such a self-inflating bag.

[MetroMPG]

The Firefly + boat tail is considerably shorter than the most popular vehicle sold year after year in the United States, anyway (Ford F-150 pickup).

So in terms of length, parking or driving it is nothing out of the "ordinary".

You're right that visibility was (obviously) an issue, and it'll be addressed in the "good" version.

[JohnNeiferd]

Maybe you've already posted this in one of the #443 posts, I haven't had time to make my way through them all yet, but I think it'd be really interesting if you could post the dimensions of your cardboard circles (length x width, we can round the edges ourselves), and the spacing between each cardboard circle. That way others could duplicate it on their Metros and test for similar results, and maybe even make a permanent version to keep on their Metro.

[luvit]

here buddy. you're famous.
Archive for Do-it-yourself (DIY) : Gas 2.0

[Wonderboy]

here buddy. you're famous.

uh..although ben didn't submit that story, he's a writer at gas2.0, so it doesn't surprise me at all to see this story featured there. The boattail has been featured on a number of "bigger" sites than that (not to discredit gas2.0). Have you seen all the linkbacks at the top of the page near the thread tools? Since I'm subscribed to the thread, about every other day I'll get an email about another linkback from some auto blog site here in the states or in italy, denmark, japan, etc. Pretty exciting. There are some amusingly weak arguments against it on some of the sites too like "if everyone did that, there would be more congestion because there would be more space occupied by each car"

[MetroMPG]

Originally Posted by JohnNeiferd

Maybe you've already posted this in one of the #443 posts, I haven't had time to make my way through them all yet, but I think it'd be really interesting if you could post the dimensions of your cardboard circles

John: I haven't done that yet, but I will within the next week.

The car still has the tail on it, but I'm being evicted from my borrowed garage parking space and need to get rid of the tail. (I don't have room to store it.) I'll post the dimensions when I "deconstruct" it.

[luvit]

i don't check backlinks. i didn't know he authored there.
but i did figure a smaller blog meant there were many larger sites posting this.
i guess this was just the first time i aciddently crossed the info...
after i posted here, i saw bajoos' aerocivic on the same page. lol

[MetroMPG]

Tail's off the car. Car is shivering, parked outside again.

FYI, the tail actually weighed 18 lbs / 8.2 kg. I had estimated 12 lbs / 5.4 kg before (that's the weight I listed in the video).

John: I'll post basic measurements in a few minutes. You should be able to reproduce this without knowing the sizes of each of the intermediate bulkheads because it's a simple shape with straight top & sides. You really only need to know the beginning and end dimensions / angles to duplicate it. (Using string to measure/fill in as many or few additional bulkheads as you want.)

[MetroMPG]

... in inches:





Notes on these measurements...

• The 17.0 inches measurement from the ground up will depend on the Metro's ride height.

• 6.5 degrees on the bottom is the final angle. It actually starts at around 4 degrees and curves to up 6.5 at the end.

• The 62.5 inches side measurement is from the forward-most part of the arc/recess in the bodywork that houses the tail light

• The 23.75 inches top measurement is the length of the Kammback, starting at the end of the "roof line" on the hatchback. The rest is cardboard.