Thread: Making the Ioniq slippier View Single Post
 03-31-2022, 04:22 PM #17 (permalink) aerohead Master EcoModder     Join Date: Jan 2008 Location: Sanger,Texas,U.S.A. Posts: 15,287 Thanks: 23,408 Thanked 6,911 Times in 4,411 Posts Cd 0.1208 is approx. solution for 60-mpg @ 80-mph It's kinda slow @ EcoModder, so I went ahead and crunched the numbers based upon the 1st-approximation values. 1) 80-miles / 60-mpg = 1.3333-gallons/ hour 2) 1.3333-gallons x 111,836-Btu / gallon ( E10 REGULAR gas ) = 149,114.66 Btus / hour 3) 149,114.66-Btu / 2546-Btu/hp = 58.5682-hp gross input energy value 4) 58.5682-hp x 0.40 ( estimated engine thermal efficiency ) = 23.4272- Brake horsepower ( bhp ) 5) 23.4272-bhp x 0.978 ( @ est. 2.2% accessory losses [ Argonne National Laboratory ] ) = 22.91188-hp 6) 22.91188-hp x 0.95 ( 95% transaxle mechanical efficiency [ Argonne National Laboratory ] ) = 21.766286-hp Road Load -------------------------------------------------------------------------------------- 7) 21.766286-hp - 11.5347-hp (rolling-resistance [from original calculations ] = 10.231586-hp ( aerodynamics ) -------------------------------------------------------------------------------------- 8) 10.231586-hp = 117.333 feet/second velocity / 550- pound-feet torque/ horsepower ( 0.5 x 0.00238 slugs x Cd ? x 24.223-square-feet frontal area ( estimated @ 85.5% of gross area ) x 117.333 feet/second-squared ) 9) solving left side outside parentheses algebraically: = 47.96069563 = right side of equal sign ( 396.8398168 x Cd? ) 10) or, 47.96069563 = ( 396.8398168 x Cd ? ) 11) divide each side by 396.8398168 12) 0.12085 = Cd (unknown) or, Cd 0.1208 satisfies the condition for 60-mpg @ 80-mph. ------------------------------------------------------------------------------------- 13) Since we're talking about profile drag, examining the profiles of vehicles exhibiting Cd 0.1208 may provide insight into the architectures which generate this coefficient, or near it; and the kinds of features the IONIQ might benefit from. Some will be Bonneville streamliners, solar cars, and SAE / Shell marathon racers, of shapes that wouldn't necessarily lend themselves to a passenger car: * JCB Dieselmax , 2018, Cd 0.117 * Goldenrod, 1965, Cd 0.117 * MANTA, MIT, 1995, Cd 0.12 * Autonoma de Mexico, 1996, Cd 0.12 * Honda Dream, 1990. Cd 0.12 * MG EX 181, 1957, Cd 0.12 * Walter Lay, Model#22, 1933, Cd 0.12 * 'Baby 'template'', 2017, Cd 0.1209 * GM Sunraycer, 1987, Cd 0.125 ( as raced ) __________________ Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/