The Electric Car
in [Design]
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From: Jim Thompson on 1 Aug 2007 10:18 On Tue, 31 Jul 2007 23:09:20 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Wed, 01 Aug 2007 00:45:24 -0500, Spehro Pefhany ><speffSNIP(a)interlogDOTyou.knowwhat> wrote: > [snip] >> >>I suspect Spandex is better than nothing. More slippery than hairy >>surfaces and it could prevent the energy-sapping oscillation of fatty >>and/or dangly bits. > > >Well, I suppose some people are more viscous than others. Certainly more vicious ;-) > > >> >>Interesting that modern hybrids apparently get better gas milage in >>city driving rather than highway. > >We have a friend who bought a Toyota hybrid. But hauling all those >batteries up and down the hills here apparently isn't efficient... her >mileage is mediocre. > > >>Eg. Prius 60mpg city, 51mpg highway > >People don't buy Prius' to save gas, they buy them to be hip and >stylish. So instead of smog, we have clouds of smug. > >John > > Bwahahahahahaha! ...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: Jim Thompson on 1 Aug 2007 11:26 On Wed, 01 Aug 2007 07:15:06 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Wed, 01 Aug 2007 06:22:36 -0700, MooseFET <kensmith(a)rahul.net> >wrote: > >>On Jul 31, 9:12 pm, krw <k...(a)att.bizzzz> wrote: >>> In article <1185930451.854228.138...(a)x35g2000prf.googlegroups.com>, >>> kensm...(a)rahul.net says... >>> >>> >>> >>> > On Jul 31, 7:21 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >>> > Web-Site.com> wrote: >>> > > On Mon, 30 Jul 2007 20:02:28 -0700, Richard Henry >>> >>> > > <pomer...(a)hotmail.com> wrote: >>> > > >On Jul 30, 7:20 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >>> > > >Web-Site.com> wrote: >>> > > >> On Mon, 30 Jul 2007 19:12:03 -0700, Richard Henry >>> >>> > > >> <pomer...(a)hotmail.com> wrote: >>> > > >> >On Jul 30, 5:48 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >>> > > >> >Web-Site.com> wrote: >>> > > >> >> On Mon, 30 Jul 2007 17:30:01 -0700, "J.A. Legris" >>> >>> > > >> >> >- I said fuel consumption will never decrease much unless cars are >>> > > >> >> >much lighter, but even radically lighter vehicles are no long-term >>> > > >> >> >solution on this overpopulated planet >>> >>> > > >> >> Amen! I keep telling people that, and they look at me like I'm some >>> > > >> >> kind of idiot. >>> >>> > > >> >You have also told us how you like to drive your big import illegally >>> > > >> >fast and tried to rationalize it by claiming that among the vehicle's >>> > > >> >luxury features is that it runs more efficiently at high speed. >>> >>> > > >> I didn't rationalize anything. However I do agree that leftist >>> > > >> weenies should be taxed more heavily to support my excesses ;-) >>> >>> > > >> And I certainly have no problem with YOU driving a tin can, just NOT >>> > > >> my children and grandchildren ;-) >>> >>> > > >OOHH!. Think of the children... >>> >>> > > >You sound like a leftist weenie. >>> >>> > > >Please explain again the more-efficient-at-higher-speed feature. >>> >>> > > I don't ever recall saying "more-efficient-at-higher-speed". >>> >>> > > But I guess it WOULD depend on your definition. The engine is >>> > > optimized right around 3000RPM (85MPH), but external drag is higher. >>> >>> > If you shift to a lower gear, 3000 RPM is at a lower speed. If there >>> > isn't an issue that is well modeled by a fuel leak, the milage would >>> > improve. >>> >>> Ever consider that transmissions aren't equally efficient in all >>> gears >> >>Yes but he didn't report he was driving with a faulty one. >> >>> and perhaps the over-drive locked-up may be a tad more >>> efficient than the lower gears? >> >>A tad but not enough to make the difference. The energy per mile >>increases as the square of the speed. > > >Not in this graph: > >http://www.fueleconomy.gov/feg/driveHabits.shtml > >I've seen a few other mpg-vs-speed curves, and they all look similar. >Looks like aerodynamic drag starts to seriously kick in above 55 MPH. > >John You need to look at engine horsepower and torque versus RPM as well. Drag DOES depend on body shape. ...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: John Larkin on 1 Aug 2007 11:32 On Wed, 01 Aug 2007 07:16:09 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >On Wed, 1 Aug 2007 00:12:10 -0400, krw <krw(a)att.bizzzz> wrote: > >>In article <1185930451.854228.138310(a)x35g2000prf.googlegroups.com>, >>kensmith(a)rahul.net says... >>> On Jul 31, 7:21 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >>> Web-Site.com> wrote: >[snip] >>> > >>> > I don't ever recall saying "more-efficient-at-higher-speed". >>> > >>> > But I guess it WOULD depend on your definition. The engine is >>> > optimized right around 3000RPM (85MPH), but external drag is higher. >>> >>> >>> If you shift to a lower gear, 3000 RPM is at a lower speed. If there >>> isn't an issue that is well modeled by a fuel leak, the milage would >>> improve. >> >>Ever consider that transmissions aren't equally efficient in all >>gears and perhaps the over-drive locked-up may be a tad more >>efficient than the lower gears? There is also work done just >>spinning the engine. Me thinks you're wrong. > >Don't both Honda and Toyota have models with CVT (continuously >variable transmission) which keeps engine RPM's in a narrow/optimum >range? > > ...Jim Thompson CVTs are still the holy grail of car design, but none of them seem to work at serious horespowers. They are the equivalent of a switching regulator. John
From: Spehro Pefhany on 1 Aug 2007 11:33 On Wed, 01 Aug 2007 08:26:13 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >On Wed, 01 Aug 2007 07:15:06 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Wed, 01 Aug 2007 06:22:36 -0700, MooseFET <kensmith(a)rahul.net> >>wrote: >> >>>On Jul 31, 9:12 pm, krw <k...(a)att.bizzzz> wrote: >>>> In article <1185930451.854228.138...(a)x35g2000prf.googlegroups.com>, >>>> kensm...(a)rahul.net says... >>>> >>>> >>>> >>>> > On Jul 31, 7:21 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >>>> > Web-Site.com> wrote: >>>> > > On Mon, 30 Jul 2007 20:02:28 -0700, Richard Henry >>>> >>>> > > <pomer...(a)hotmail.com> wrote: >>>> > > >On Jul 30, 7:20 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >>>> > > >Web-Site.com> wrote: >>>> > > >> On Mon, 30 Jul 2007 19:12:03 -0700, Richard Henry >>>> >>>> > > >> <pomer...(a)hotmail.com> wrote: >>>> > > >> >On Jul 30, 5:48 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >>>> > > >> >Web-Site.com> wrote: >>>> > > >> >> On Mon, 30 Jul 2007 17:30:01 -0700, "J.A. Legris" >>>> >>>> > > >> >> >- I said fuel consumption will never decrease much unless cars are >>>> > > >> >> >much lighter, but even radically lighter vehicles are no long-term >>>> > > >> >> >solution on this overpopulated planet >>>> >>>> > > >> >> Amen! I keep telling people that, and they look at me like I'm some >>>> > > >> >> kind of idiot. >>>> >>>> > > >> >You have also told us how you like to drive your big import illegally >>>> > > >> >fast and tried to rationalize it by claiming that among the vehicle's >>>> > > >> >luxury features is that it runs more efficiently at high speed. >>>> >>>> > > >> I didn't rationalize anything. However I do agree that leftist >>>> > > >> weenies should be taxed more heavily to support my excesses ;-) >>>> >>>> > > >> And I certainly have no problem with YOU driving a tin can, just NOT >>>> > > >> my children and grandchildren ;-) >>>> >>>> > > >OOHH!. Think of the children... >>>> >>>> > > >You sound like a leftist weenie. >>>> >>>> > > >Please explain again the more-efficient-at-higher-speed feature. >>>> >>>> > > I don't ever recall saying "more-efficient-at-higher-speed". >>>> >>>> > > But I guess it WOULD depend on your definition. The engine is >>>> > > optimized right around 3000RPM (85MPH), but external drag is higher. >>>> >>>> > If you shift to a lower gear, 3000 RPM is at a lower speed. If there >>>> > isn't an issue that is well modeled by a fuel leak, the milage would >>>> > improve. >>>> >>>> Ever consider that transmissions aren't equally efficient in all >>>> gears >>> >>>Yes but he didn't report he was driving with a faulty one. >>> >>>> and perhaps the over-drive locked-up may be a tad more >>>> efficient than the lower gears? >>> >>>A tad but not enough to make the difference. The energy per mile >>>increases as the square of the speed. >> >> >>Not in this graph: >> >>http://www.fueleconomy.gov/feg/driveHabits.shtml >> >>I've seen a few other mpg-vs-speed curves, and they all look similar. >>Looks like aerodynamic drag starts to seriously kick in above 55 MPH. >> >>John > >You need to look at engine horsepower and torque versus RPM as well. > >Drag DOES depend on body shape. > > ...Jim Thompson For a given shape, at automotive speeds, I think there is a square law relationship between air speed and drag. 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: John Larkin on 1 Aug 2007 11:46
On Wed, 01 Aug 2007 08:26:13 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >On Wed, 01 Aug 2007 07:15:06 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Wed, 01 Aug 2007 06:22:36 -0700, MooseFET <kensmith(a)rahul.net> >>wrote: >> >>>On Jul 31, 9:12 pm, krw <k...(a)att.bizzzz> wrote: >>>> In article <1185930451.854228.138...(a)x35g2000prf.googlegroups.com>, >>>> kensm...(a)rahul.net says... >>>> >>>> >>>> >>>> > On Jul 31, 7:21 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >>>> > Web-Site.com> wrote: >>>> > > On Mon, 30 Jul 2007 20:02:28 -0700, Richard Henry >>>> >>>> > > <pomer...(a)hotmail.com> wrote: >>>> > > >On Jul 30, 7:20 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >>>> > > >Web-Site.com> wrote: >>>> > > >> On Mon, 30 Jul 2007 19:12:03 -0700, Richard Henry >>>> >>>> > > >> <pomer...(a)hotmail.com> wrote: >>>> > > >> >On Jul 30, 5:48 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >>>> > > >> >Web-Site.com> wrote: >>>> > > >> >> On Mon, 30 Jul 2007 17:30:01 -0700, "J.A. Legris" >>>> >>>> > > >> >> >- I said fuel consumption will never decrease much unless cars are >>>> > > >> >> >much lighter, but even radically lighter vehicles are no long-term >>>> > > >> >> >solution on this overpopulated planet >>>> >>>> > > >> >> Amen! I keep telling people that, and they look at me like I'm some >>>> > > >> >> kind of idiot. >>>> >>>> > > >> >You have also told us how you like to drive your big import illegally >>>> > > >> >fast and tried to rationalize it by claiming that among the vehicle's >>>> > > >> >luxury features is that it runs more efficiently at high speed. >>>> >>>> > > >> I didn't rationalize anything. However I do agree that leftist >>>> > > >> weenies should be taxed more heavily to support my excesses ;-) >>>> >>>> > > >> And I certainly have no problem with YOU driving a tin can, just NOT >>>> > > >> my children and grandchildren ;-) >>>> >>>> > > >OOHH!. Think of the children... >>>> >>>> > > >You sound like a leftist weenie. >>>> >>>> > > >Please explain again the more-efficient-at-higher-speed feature. >>>> >>>> > > I don't ever recall saying "more-efficient-at-higher-speed". >>>> >>>> > > But I guess it WOULD depend on your definition. The engine is >>>> > > optimized right around 3000RPM (85MPH), but external drag is higher. >>>> >>>> > If you shift to a lower gear, 3000 RPM is at a lower speed. If there >>>> > isn't an issue that is well modeled by a fuel leak, the milage would >>>> > improve. >>>> >>>> Ever consider that transmissions aren't equally efficient in all >>>> gears >>> >>>Yes but he didn't report he was driving with a faulty one. >>> >>>> and perhaps the over-drive locked-up may be a tad more >>>> efficient than the lower gears? >>> >>>A tad but not enough to make the difference. The energy per mile >>>increases as the square of the speed. >> >> >>Not in this graph: >> >>http://www.fueleconomy.gov/feg/driveHabits.shtml >> >>I've seen a few other mpg-vs-speed curves, and they all look similar. >>Looks like aerodynamic drag starts to seriously kick in above 55 MPH. >> >>John > >You need to look at engine horsepower and torque versus RPM as well. Don't tell me what I need to do. > >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 |