The Electric Car
in [Design]
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From: Eeyore on 1 Aug 2007 12:31 Richard Henry wrote: > Jim Thompson wrote: > > > > Drag DOES depend on body shape. > > If you look at new cars offered for sle today, the shapes are all > pretty much the same, especially when compared to the wide variations > on the market 40-50 years ago. I imagine that is because everybody's > wind tunnels give the same answers. Tatra (Czech) apparently knew the answer over 70 years ago. http://en.wikipedia.org/wiki/Tatra_T77 Cd said to be 0.212 Cd alone is only half the answer. Frontal area is equally important so the US trend for large high-riding vehicles with a poor shape for drag loses on all points. Automobile examples of CdA ft� are shown below: CdA ft� Automobile model 3.95 1996 GM EV1 5.10 1999 Honda Insight 5.71 1990 Honda CR-X Si 5.76 1968 Toyota 2000GT 5.80 1986 Toyota MR2 5.81 1989 Mitsubishi Eclipse GSX 5.88 1990 Nissan 240SX 5.92 1994 Porsche 911 Speedster 5.95 1990 Mazda RX7 6.00 1970 Lamborghini Miura 6.13 1993 Acura NSX 6.17 1995 Lamborghini Diablo 6.27 1986 Porsche 911 Carrera 6.27 1992 Chevrolet Corvette 6.35 1999 Lotus Elise 6.40 1990 Lotus Esprit 6.54 1991 Saturn Sports Coupe 6.57 1985 Chevrolet Corvette 6.77 1995 BMW M3 6.79 1993 Toyota Corolla DX 6.81 1991 Subaru Legacy 6.90 1993 Saturn Wagon 6.93 1982 Delorean DMC-12 6.96 1988 Porsche 944 S 6.96 1995 Chevrolet Lumina LS 7.02 1992 BMW 325I 7.04 1991 Honda Civic EX 7.10 1995 Saab 900 7.14 1995 Subaru Legacy L 7.34 2001 Honda Civic 7.39 1994 Honda Accord EX 7.48 1993 Chevrolet Camaro Z28 7.57 1992 Toyota Camry 7.69 1994 Chrysler LHS 7.72 1993 Subaru Impreza 8.70 1990 Volvo 740 Turbo 8.70 1992 Ford Crown Victoria 8.71 1991 Buick LeSabre Limited 9.54 1992 Chevrolet Caprice Wagon 10.7 1992 Chevrolet Blazer 11.6 2005 Ford Escape Hybrid 11.7 1993 Jeep Grand Cherokee 16.8 2006 Hummer H3 17.4 1995 Land Rover Discovery 26.5 2003 Hummer H2 Graham
From: Ren� on 1 Aug 2007 13:16 On Wed, 01 Aug 2007 17:11:38 +0100, Eeyore <rabbitsfriendsandrelations(a)hotmail.com> wrote: >The official US figures don't agree with you. >http://www.fueleconomy.gov/feg/noframes/20801.shtml > >Graham OK you win :-) not sure what are the export models shown here. I was led to believe that smaller engined models could make it. (not even counting the energy in making the car!) Anyway, the "3 liter Lopo" (smaller brother of the Golf, designed for economy - 4 person 5 door car) does 70 mpg. (And, incidentally, I like a V8 Mustang a lot better:-) -- - Ren�
From: Jim Thompson on 1 Aug 2007 13:23 On Wed, 01 Aug 2007 08:46:53 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Wed, 01 Aug 2007 08:26:13 -0700, Jim Thompson ><To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: > [snip] >> >>You need to look at engine horsepower and torque versus RPM as well. > >Don't tell me what I need to do. Eh? Didn't get any last night, John? You sure are cranky ;-) > > >> >>Drag DOES depend on body shape. > > >Aero drag goes up roughly with the square of speed for most shapes. >The question is where the v^2 thing starts to dominate. The answer, >for most cars, seems to be upwards of 55 MPH. Below that, other things >seem to matter. > >John > I think, if you will follow my advice, see the horsepower peak in that region as well. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave
From: Spehro Pefhany on 1 Aug 2007 13:28 On Wed, 01 Aug 2007 10:23:13 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >On Wed, 01 Aug 2007 08:46:53 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Wed, 01 Aug 2007 08:26:13 -0700, Jim Thompson >><To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >> >[snip] >>> >>>You need to look at engine horsepower and torque versus RPM as well. >> >>Don't tell me what I need to do. > >Eh? Didn't get any last night, John? You sure are cranky ;-) > >> >> >>> >>>Drag DOES depend on body shape. >> >> >>Aero drag goes up roughly with the square of speed for most shapes. >>The question is where the v^2 thing starts to dominate. The answer, >>for most cars, seems to be upwards of 55 MPH. Below that, other things >>seem to matter. >> >>John >> > >I think, if you will follow my advice, see the horsepower peak in that >region as well. > > ...Jim Thompson I wonder at what speed a 500HP 'vette is most efficient? ;-) Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff(a)interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
From: Eeyore on 1 Aug 2007 13:44
"Ren�" wrote: > On Wed, 01 Aug 2007 17:11:38 +0100, Eeyore > <rabbitsfriendsandrelations(a)hotmail.com> wrote: > > >The official US figures don't agree with you. > >http://www.fueleconomy.gov/feg/noframes/20801.shtml > > > >Graham > > OK you win :-) > not sure what are the export models shown here. > I was led to believe that smaller engined models could make it. > > (not even counting the energy in making the car!) > > Anyway, the "3 liter Lopo" (smaller brother of the Golf, designed for > economy - 4 person 5 door car) does 70 mpg. I think you mean the 3 CYLINDER Lupo. It has a 1.2 litre turbodiesel engine. http://en.wikipedia.org/wiki/Volkswagen_Lupo Graham |