View Single Post
Old 09-01-2011, 11:15 PM   #37 (permalink)
Frank Lee
Frank Lee's Avatar
Join Date: Jan 2008
Location: up north
Posts: 12,596

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,534
Thanked 3,384 Times in 2,128 Posts
I don't think the area behind the front wheel is problematic as it was; for one it's already in a turbulent zone right behind the wheel and for two it won't act as a "parachute" because there is an AFTBODY right there. If anything it will be like the front of any bluff body in that air piles up into a bubble in front of it if it isn't pointy enough.

Also, I'd wager the canopy is very slender and boattailed from plan view too so it's probably just fine as it was, being somewhat steeper than "template".

PEOPLE listen up: concave pockets facing forward DON'T act as parachutes because one of the differences is, there is a ginormous AFTBODY right there. Parachute drag is from the high turbulent flow in the wake because there is no AFTBODY to promote orderly "closure" of flow.

Re: rr: Allert has a tire rr test setup and his skinny little 17" 125 tires could do no better than .17, and that was with a worn one in the test group, and that was at 59 psi. He noted that bicycle tires had HALF the rr. Yes, motorcycle and to a lesser extent bicycle tires really suck as far as r.r. It must be due to the lack of steel belted radial construction. Anyway, when playing with the EM performance calculator, it would be more realistic to plug in .15 if not .20.

With that in mind, I took the 17" front wheel off my Songi today and "chopped it" with a 20 x 1.9 freestyle tire and alloy BMX rim. Didn't weigh anything yet but the bike parts must weigh less than half the stockers. (Weighed: 10.5 lb Songi wheel and tire; 3.5 lb BMX at whatever resolution a digi bath scale has). Sorry, no objective/accurate measurement data but subjectively it made a world of difference! The steering response is phenomenally lighter and faster and the new tire has 65 psi as sidewall max vs 55 for the HEAVY but nicely ribbed original.

Combine that with the other recent mod, that of the driver's seat delete (now I sit on the BACK seat, about 12" lower than before! ) and I find myself cruising around at much higher speed yet seemingly not draining the battery pack any worse than before when I toddled around at sub-bicycling speeds.

Last edited by Frank Lee; 09-02-2011 at 07:41 AM..
  Reply With Quote