https://ecomodder.com/forum/member-a...april-2005.jpghttps://ecomodder.com/forum/member-a...ap-fillers.jpghttps://ecomodder.com/forum/member-a...works-aero.jpghttps://ecomodder.com/forum/member-a...speed-aero.jpgFor members and guests familiar with this talking point, and to economize on jumping from thread-to-thread, I'm offering what I know about the 'template' so far here, as a recap to my testing.
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1) Spirit of Ecomodder is the AST-III contour.
2) It has the same frontal projection as it's parent Toyota T-100.
3) Same frontal area.
4) On Spirit's first trip to the wind tunnel, measurements were also conducted for a Toyota, full-scale, blockage-ratio calibration model ( GEN-III Prius ), tested @ Japan, A2 Wind Tunnel, Mooresville, North Carolina, USA, and DARKO Technology Wind Tunnel, Ogden, Utah, USA, which measured Cd 0.25, Cd 0.26, and Cd 0.285, respectively.
5) For the iterative test results combined for Spirit, and lowest-drag configuration, simulating a very-low-drag, BEV pickup, the measurements were:
Cd 0.2010 @ DARKO, Cd 0.1826 @ A2, and Cd 0.1760 @ Toyota.
6) These would be compared to the OEM Cd 0.44, published by Toyota.
7) Front lift coefficient, CLf = - 0.00002845
8) Rear lift coefficient, CLr = + 0.00002086
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9) Speed in the mile @ Bonneville International Speedway, Wendover, Utah, USA, 105-mph ( not a top speed ).
10) Speed on I-10, west of Tucson, Arizona, accelerating to catch up with a US Homeland Security, Chevrolet Tahoe, approx. 112-mph ( not a top speed )
11) Speed of USHS Tahoe, 108-mph.
12) Approximate Cd requirement to achieve 112-mph, from OEM top speed of 96-mph @ Cd 0.44 = Cd 0.22.
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13) Highest measured 'tank' fuel economy, experienced on four separate test runs, 39.9-mpg, at 65-mph, AC 'ON.'
14) Highest OEM fuel economy 'baseline' experienced under same conditions = 25.14-mpg.
15) 'Spirit' was purchased in 2005 from 'AeroStealth' ,with 205,000 miles on the odometer.
16) AeroStealth recorded every 'fill' between 1994, and 2005.
17) Presently, Spirit has over 423,000 miles of fuel economy records.
18) I own a number of Pitot-tubes, manometers, MAGNEHELICs, and anemometers.
19) The premise of the 'Spirit' exercise was to essentially just use what Wolf-Heinrich Hucho referred to as 'aerodynamic fundamentals' and see where that would lead.
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20) This same premise scored me a land speed record at Bonneville in 1991 with 'Spindletop', my streamlined 1984, Honda CIVIC CRX and around a 13-mpg improvement compared to it's baseline; backed up by top speed and coastdown testing at the Chrysler Proving Grounds, East Chelsea, Michigan, by the late, Don Schroeder, of CAR and DRIVER Magazine, Hogback Road, Ann Arbor, Michigan. Cd 0.235, and 65-mpg @ 55-MPH National Speed Limit.
21) Spindletop participated at the July Meet, Utah Salt Flats Racing Association, July 21, 1990.
22) As 'stripped' of modifications as best as I could perform, the baseline was 89.77-mph, compared to 93-mph at Tochigi, Japan Proving Grounds.
23) The highest attained speed, with all the mods was 97.386-mph.
24) Allowing for the baseline top speed discrepancy of 3.23-mph, had I raced the car on the paved frontage road, the top speed might have been 100.786-mph.
25) The 12-inch boat-tail, with taped-off Mustang GT diffuser was good for a 5.81-mph top speed increase by itself ( template ).
26) Leaving Bonneville, with all the cardboard and duct tape modifications, Spindletop returned 65-mpg for the its first time.
27) At the Chrysler Proving Grounds, the car averaged 98-mph on the 5-mile oval, both directions.
28) Coastdown tests indicated a Road-Load horsepower of 8.55-hp, @ 50-mph, compared to 10.0-hp @ 50-mph for the OEM car tested in Japan.
Weather conditions at Chrysler were:
* 42 F dry-bulb
* 49 F wet-bulb
* 29.15" Hg barometric pressure
* Wind- zero
29) Over the telephone, I shared Spindletop's numbers with aerodynamicist Glen Scharpf, of General Motors Aerodynamics Laboratory, and he figured that it would be okay to attribute Cd 0.235 to the modified car, based on top speed, fuel economy, and the coastdowns.
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The 'Baby' template scale-model was tested on the second trip to DARKO in 2017, where we got more configurations measured for 'Spirit', tested Gumby 79's RAM pickup, and 'Baby.'
30) 'Baby' is 36.68% - scale model of the AST-III, the most 'aggressive' contour. A short list of specs are:
* Length- 2476.5mm
* Width - 706.12mm
* Height - 647.192mm
* height - 537.972mm
* Ground clearance - 109.22mm
* Tire width - 64mm
* Diffuser - 2.8-degrees
* Front track - 625,475mm
* Rear track - 463.55mm
* Wheel - base 1054.1mm
* Forebody - 591.87mm
* Aft-body (LH)- 1884.629mm ( 76.1%-L )
* Aft-body (KH)- 1141.679mm ( 65.85%-L )
* Verjungungsverhaltnis ( LH ) 3.50321
* Verjungungsverhaltnis ( KH ) 2.12219
* Frontal projected area ( Af ) 3.4795-sq-ft (0.32356 m-sq ) ( 73.32% of gross ).
* Tunnel test section = approx. 100-sq-ft ( 9.29 m-sq )
* Test section blockage-ratio approx. 3.479%
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Performance:
* Long-tail = Cd 0.1209
* Short-tail = Cd 0.148
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Comments:
* The tire-to-wheel fairing gap was sizable, as until I got to the wind tunnel, I had no idea how 'Baby' would be attached to the ground board.
* Also, the tension straps which secured 'Baby' to the ground board were exposed to the airstream.
* These are unknown quantities.
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For any who haven't seen the videos shot at DARKO, the 1st session is at:
'Streamlined Toyota T-100 In the wind tunnel'
And the 2nd session can be seen at You-Tube:
Z2FU9Sm2qLY
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The future plan is to complete the mods I couldn't finish in 2017, and make the trip to the A2 Wind Tunnel in Mooresville, North Carolina.
There is an all-new boat-tail, plus double stingers which will allow a simulation of a fully-gap-filled, full boat-tailed, one-wheeled trailer; with a wake only large enough to accommodate a license plate and tail lights.
The 'trailer' could be a 'transformer' mini RV camping trailer, or range-extender fuel cell or auxiliary battery pack. Either way, it's a means to explore a near-separation-free structure, within a controlled environment.
If the numbers are good, I'll use the mockup as a 'plug', from which to make female tooling, and layup a lightweight counterpart, to enjoy on the open road.
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If my single remaining brain cell comes up with something I've over-looked, I'll just tack it on here.
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'template' pressure coefficient profile'
1) if anyone has the book, 'BOUNDARY-LAYER THEORY', by Prof. Hermann Schlichting, on page-22, in Figure 1.12, he presents results of pressure tap measurments conducted for various streamline bodies of revolution, by G. Fuhrmann in 1910.
2) the architecture of 'Model-II', and it's pressure profile, while for a higher fineness ratio for the 'template', does allow a glimpse into, what appears to be the most misunderstood 'pressure-related effects' associated with streamline bodies.
This is at the root of one of the biggest controversies ever experienced here at EcoModder.com.
I'll endeavor to 'learn' how to post images, but it may take awhile.
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template 'supervelocity'
This is a tidbit from professors Daugherty and Franzini:
* The measured distance over the nose of the 'templates', to the roof apex, is 42% longer than the distance flow at infinity travels at any given velocity.
* In a wind tunnel, with a smoke rake, where the rearview mirror mounts to the windshield, one would witness the streamlines attain their most closely-spaced distance from one another, the maximum supervelocity of 142%, lowest static pressure ( suction peak ), for the entire body, after which, the flow would begin its deceleration down the diminishing body cross-section, and pressure recovery, as a consequence of Daniel Bernoulli's velocity/pressure tradeoff.
* Ultimately, the flow would rise in to positive static pressure, before departing the trailing edge of the body.
* In 'standard air', the 'templates' would be transonic at 514-mph ( 828.5-km/h ), with MACH-1, supersonic flow occurring outside the windshield where the rearview mirror is mounted.
* At 115.5-mph road velocity( 186 km/h ) air velocity at the suction peak on the 'templates' would achieve 165-mph ( 265 km/h ), same as Hurricane Otis, coming ashore in Acapulco, Mexico, and pressure outside the upper windshield would be at 932-millibar, vs 1013-millibar, at an isolated distance from the car.
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