View Single Post
Old 12-07-2019, 01:40 PM   #95 (permalink)
aerohead
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 15,892
Thanks: 23,969
Thanked 7,221 Times in 4,648 Posts
2nd look at Cybertruck yields Cd 0.281

I photo-enlarged the exoskeleton image onto 11 X 17 paper and went after it with drafting instruments.
A non-Tesla website provided estimates for critical dimensions and power consumption.
Working with the Motor Trend testing of the Model S I was able to isolate aero, then rolling-resistance power loads.
From the Cybertruck's estimated power consumption I calculated road horsepower of 41.8839-hp,at 65-mph.Using the footprint of the truck,compared to the Model S,I estimated 6,041-pounds EPA test weight for Cybertruck.Using the same R-R coefficient as the Model S,I subtracted that value out,to leave the remaining aero horsepower of 20.3499 horsepower at 65-mph.Reverse-engineering for drag coefficient with the 38.53-sq-ft frontal area calculated from the drawing left Cd0.281 to achieve power balance.
--------------------------------------------------------------------------
Body observations:
*optimized low nose
*optimized nose shape
*nose side chamfering = zero separation
*nose-frunk-windscreen slope = favorable pressure regime
*upper half of wind screen is curved
*front quarter panels have plan taper/camber
*the body possesses a seven different body widths to achieve almost imperceptible camber
*frontal area occurs at the roof apex line/between doors
*airflow is 'attacking' the body all the way to the apex line
*from wind tunnel tuft-testing image,there is no edge separation or vorticity in the forebody (1968 Alfa Romeo Calabo,by Nuccio Bertone)
*upper rear windscreen is curved
*from the Bearman et al. research of 1984,the Cybertruck's 10-degree-sloped greenhouse does not have any vortex-induced drag at all
*the greenhouse's est. 27.5-degree tumblehome is not necessary to prevent edge vorticity
*the wheel arch blisters may provide splash and spray protection and could conceivably produce a Whitcomb-waisting function,adding frontal area as both body cross-section both grows and declines
*the aft-body is boat-tailed
*the aft separation line provides for perfect 'burst'
*aside from a locked-vortex just behind the roof apex,the descending roof-line is separation-free,with pressure recovery all the way to the separation line of the tailgate.
*the belly is perfect
*there is no cab-to-bed gap.
*wheel covers should prove to be low drag
*lack of side mirrors is good for a 0.010 drag reduction
-------------------------------------------------------------------------
*L/H = 3.3705,at 8-inch ground clearance,which in other cars produces Cd 0.24-to-Cd 0.150
*L/h = 3.814,which in other cars produces Cd 0.367-to-Cd 0.15
*Aft-body is 56.94% of overall body length,which in other cars produces Cd 0.20-to-Cd 0.137
-------------------------------------------------------------------------
Other vehicles with the same profile drag (normalized to same frontal area):
1924 Rumpler Tropfen-wagen limousine
1935 FKFS J-form model @ 45% aft-body
1937 Peugeot 402 (Jean Andreau)
1967 Toyota 2000 GT (numerical model)
1969 Dodge Charger Daytona
1975 Renault ALPINE 610
1985 Buick Wildcat concept
1985 Renault ALPINE GTA
1985 Renault ALPINE V-6 Turbo
1985 Panther Quasar
1988 Peugeot 405 Mi16
1990 Citroen XM
1993 Lexus LS
1996 Porsche 911 GT1
1997 Audi A6/S6
2003 SAAB 9-3
2005 VW Passat 3.6
2006 Porsche 996
2010 Ferrari 599XX
2010 HONDA Insight-II
2011 Chev. VOLT-I
2011 Chev. Corvette C-6 ZO6
2011 Nissan LEAF-I
2011 VOLVO S60 T6 AWD
2012 Chev. Malibu
2012 Toyota Prius-C
2012 Hyundai Elantra
2013 VW Jetta Hybrid
2014 Mitsubishi Mirage
2014 Hyundai Sonata
2014 Lexus IS 350 FSport
2016 Toy. Camry
2016 Toy. Avalon
2016 Toy.Corrola
2016 Dodge Dart
2016 Chev. VOLT-II
2016 Hyundai Accent
2016 BMW 4-Series
2016 BMW 6-Series
2016 VW Passat CC
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/

Last edited by aerohead; 12-07-2019 at 04:44 PM.. Reason: ad data
  Reply With Quote