1/2-tonneau/1/2-aero-shell - Fuel Economy, Hypermiling, EcoModding News and Forum

aerohead · 08-20-2011, 01:57 PM

One of the members asked about this.I'd never submitted it and there are no photos of it in the archives so I decided to do an independent thread for it.
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Before I did the aero-shell,and while John Gilkison still owned the T-100 I had one of those 'what if' moments,wondering what would happen if you combined GM's patented 1/2-tonneau with 1/2 of an aero-shell.
I talked with Gilkison over the phone and he relayed some measurement data from the truck.
He was already running a 1/2-tonneau so I merely constructed a blister which embodied only the back half of an aero-shell.
When it was complete,I strapped it to the hood of the CRX and drove it north to Ten Killer Lake in Oklahoma where he was vacationing.
We screw-attached it from below,caulked the seam,and that was it.
While John drove,I busied myself in the bed of the truck with a ski-pole tuft wand,watching the airflow as we circled the lake boundary.Flow was good.
The bummer was that he had not considered rear vision and it definitely created a blind spot.( Later when Bob Parsons did his Chevy truck we held the height at 'mirror line of sight' height ).
After some good swimming I departed.
After the drive home,dodging a tornado on I-40,John reported a definite mpg increase.And after suffering about a year with the blind-spot the blister was retired to the landfill.
John said it was good for 8% mpg HWY.That would be a 16% drag reduction,or Cd 0.37 for the truck,down from Cd 0.44.
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I located the photos this morning and Al says he can get them scanned today,so I'll post those asap.