View Single Post
Old 07-31-2019, 10:48 AM   #92 (permalink)
aerohead
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 11,306
Thanks: 18,223
Thanked 6,003 Times in 3,657 Posts
coast down

Quote:
Originally Posted by Snax View Post
I am about to give up on tracking actual efficiency with this thing on any short term kind of basis. It is simply proving too inconsistent to be indicative of anything at this point.

I could be wrong, but my gut tells me that the addition of discs front and rear, as well as half skirts on the rear have reduced drag, but my numbers simply don't reflect that even when testing in conditions that are virtually identical to unmodified test conditions. There must be something different, but not sure what - or perhaps even the possibility that discs and skirt actually hurt drag. Could that be??

I've decided that the only thing that is going to produce any usable short term A-B-A data is the coast down test. Eliminating drivetrain variables will be the only way to see what is actually happening with each mod unless I want to spend countless hours driving around for little other reason.

I'm gonna need a different test road . . :/
Many automakers switched to wind tunnel testing from coast down testing,as there were as few as 7-days a year when the meteorological conditions were stable enough to actually allow the necessary parameters to be satisfied.
I've tried it,gave up,and paid to have it done at a research facility under continuous weather monitoring.Data resolution has to be at 10 measurements/second resolution,perfectly straight course,dry,wind zero,or less than,or at minimums,ten-run minimum,back-to back,immediately.All the polar-moments-of-inertia for every rotating component on the vehicle must be known,or properly estimated,using SAE protocols. Exact mass of vehicle and test driver.It's a daunting proposition even following their mathematics.
Good luck!
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
The Following User Says Thank You to aerohead For This Useful Post:
Snax (07-31-2019)