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Old 10-21-2020, 03:58 PM   #14 (permalink)
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best Cd

Originally Posted by Cd View Post
Phil, welcome back. ��
I hadn't seen this particular Youtube video, and wasn't aware you tested the truck without the mirror.
It looks as though you also taped up the gap behind the bed in this test.
What was your best Cd on the truck, and what Cd of the template model you had tested ?
Here are some of the raw numbers : Trip-one
1) 840- pound weight penalty
2) Cd 0.2675 as driven, Spirit-I
3) Cd 0.251 with folded OEM mirrors
4) Cd 0.2435 with OEM mirror delete
5) 30-pounds downforce @ front @ 135-mph ( on a 4220-pound vehicle )
6) 22-pounds rear lift @ rear @ 135-mph ( on a 4220-pound vehicle )
7) Toyota Prius calibration model = Cd 0.285 @ DARKO
8) Toyota Prius calibration model = Cd 0.26 @ A2 Wind Tunnel
9) Toyota Prius calibration model = Cd 0.25 @ Toyota full-scale wind tunnel
10) 100% grille block = Delta Cd 0.027
11) Dodge Viper windshield / cowl seal = Delta Cd 0.005
12) Dual SCCA racing mirror delete = Delta Cd 0.010
13) 'Unibody' simulation ( cab-to-bed gap seal ) = Delta Cd 0.016
14) Cut line, body gap taping = Delta Cd 0.000
15) Cd 0.3445 as driven ( no boat-tail, no stinger ) If lift was measured we didn't discuss it. I wasn't interested, as without the tail and stinger, she was 'incomplete.' If lift data was recorded, it will be on the CD that Layne presented us.
15-A ) For the 4,687-mile trip, Spirit-II returned:
* 29.435-mpg @ 70-mph
* 32.798-mpg @ 65-mph
* 36.968-mpg @ 55-mph
* 31.814-mpg trip average
All on Regular Unleaded gasoline
If one takes the data from the two trips and associates it with the original numbers, the following are indicated:
16) Spirit with Dodge Viper windshield/ cowl seal = Cd 0.2625
17) Number ( 16) Spirit with 'cameras' = Cd 0.2525
18) Number ( 17 ) Spirit as a BEV ( cooling delete ) = Cd 0.2255
19) Number ( 18 ) Spirit with restored belly / diffuser function = Cd 0.1755
20) Number ( 19) Spirit with 'Unibody' = Cd 0.1595
21) Number ( 20 ) Spirit with stinger = Cd 0.1325
22) If the Prius calibration model quanta is factored in, it suggests that if Spirit was tested in the A2 Wind tunnel, under the number 21) configuration it might indicate Cd 0.1208, and Cd 0.1161 at the Toyota wind tunnel.
These are all just estimates, but the speed and mpg suggest a significant drag reduction compared to the OEM configuration. Spirit has returned 39.9 mpg on three occasions. 900-miles plus on a tank of gas gets kinda interesting.
23) the 'baby' template, long-tail, 1/3rd-scale model was Cd 0.1209
24) the ' baby' template, short-tail was Cd 0.148 ( which includes complete loss of the wheel fairing boat-tailing ).
The new stinger is complete. The new boat-tail lacks about a months work to complete. In order to get the new tail on the truck will require some concrete flooring and a gantry crane in the shop and a low-water crossing driveway repair. I'm doing a pit in the shop floor as well.
If I can keep the truck running, I'll try for the A2 Wind Tunnel, since we've lost DARKO. I've cut all extraneous spending, and am saving for a used EV. I've got green energy at home and would like to be driving on it ASAP.
Photobucket album:

Last edited by aerohead; 10-23-2020 at 10:51 AM.. Reason: add data
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