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Old 12-06-2009, 10:29 PM   #262 (permalink)
Master EcoModder
Join Date: Nov 2009
Location: Leadville, CO
Posts: 509

Maroon Ballon - '98 Chrysler Town & Country LXI
90 day: 26.42 mpg (US)

MaEsTRO - '95 Geo Metro 5spd hatch, 3 cyl
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Originally Posted by MetroMPG View Post
All the other aero stuff I've done upstream affects the performance of the tail - meaning it wouldn't work as well without these:
  • partial grille block,
  • headlight gaps sealed
  • hood/bumper gap closed
  • pass mirror delete,
  • partial cowl block,
  • wipers were off
  • smooth wheel covers
  • rear fender skirts
  • and the big one: full smooth undertray
  • EDIT: forgot radio antenna delete
Obviously, your recent test results reflect the sum of all your modifications. But (please correct me if I'm wrong), if there is one area that made more of a difference, it seems like work on the aft portion of the car netted bigger results than work on the other areas.

This does seem to be the case with recumbent bicycles. On a recumbent, you present a significantly smaller frontal area, and having done that, even though the air is very dirty forward of the CG, with legs, feet, crank, front wheel, etc., churning the air, once the airflow is past that point, if you can smooth it out and get it to reattach with a rear fairing, you get more speed results than with a front fairing.

A front fairing will give you more comfort than a rear fairing, but there are issues of visibility and the mechanics of steering at the front of the vehicle that make it more complicated. A completely enclosed bike is optimal for efficiency, but crosswind stability and just being able to put your feet on the ground are issues. But if you're going to try to get the most out of one single area, bringing the air back together at the stern seems to work better than cutting through it at the bow.

It looks like your test results corroborate this theory.
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The Following 2 Users Say Thank You to thatguitarguy For This Useful Post:
aerohead (12-09-2009), Frank Lee (12-06-2009)