EV Digest 6927
Topics covered in this issue include:
1) Re: Zombie rises from the dead Siamese8 lives again
by Bill Dube <[EMAIL PROTECTED]>
2) whats the difference between gearing a motor for speed vs distance
by "gulabrao ingle" <[EMAIL PROTECTED]>
3) RE: 55mph - calculating HP
by "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
4) Re: 55mph
by "Peter Gabrielsson" <[EMAIL PROTECTED]>
5) RE: 55mph - calculating HP
by "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
6) RE: 55mph - calculating HP
by Steve Peterson <[EMAIL PROTECTED]>
7) RE: 55mph - calculating HP
by Christopher Robison <[EMAIL PROTECTED]>
8) Re: 55mph - calculating HP
by Frank John <[EMAIL PROTECTED]>
9) Re: Rolling Resistance - how to measure
by "Roland Wiench" <[EMAIL PROTECTED]>
10) Re: Zombie rises from the dead Siamese8 lives again
by Bruce Weisenberger <[EMAIL PROTECTED]>
11) Re: Google presses for 100 MPG vehicle
by "Brian Pikkula" <[EMAIL PROTECTED]>
12) Re: Google presses for 100 MPG vehicle
by Lee Hart <[EMAIL PROTECTED]>
13) RE: contacting Electro Automotive (electroauto.com)
by "Florian Schmidt" <[EMAIL PROTECTED]>
14) Re: 55mph
by GWMobile <[EMAIL PROTECTED]>
15) Re: Improving hillclimbing without mudering the pack?
by Markus Lorch <[EMAIL PROTECTED]>
--- Begin Message ---
Actually, Bruce Weisenberger is who suggested that we use the Zilla
series/parallel shift signal to trigger the brush timing shift.
Using the series/parallel shift signal to trigger the brush timing
shift really made a lot o sense to me. By making a single change in
timing at a consistent point in the run, you whittle the problem down
to just playing with a couple of settings, at least to begin with.
You pick the starting line timing and the advance timing and that is it.
While not perfect, these two timing settings should be good enough to
get what we need. It is also a tractable number of variables to
optimize at the track (or dyno.) If you go with some servo that moves
the timing continuously, you have to build some sort of
multi-dimensional "fuel map" type algorithm to run the darned thing.
It is no doubt "better" but it would be very difficult to find the
best "map." One step between two timing values is not at all ideal,
but at least it is something we can easily do.
Bill Dube'
At 08:52 PM 6/20/2007, you wrote:
Should have known it would be Bill...
Actually Bill Dube and crew have already set up the
motors on Killacycle to do this very thing. Like all
untried things we'll have to wait and see how well it
works and then improve on it, if it shows promise. I
feel there is enough data to show it has merit and am
personally eager to see how it all pans out.
--- End Message ---
--- Begin Message ---
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* This post contains a forbidden message format *
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--- Begin Message ---
Waaay cool site! I found both my 1990 Nissan 240 and my Geo
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Peter Gabrielsson
Sent: Thursday, June 21, 2007 12:58
To: ev@listproc.sjsu.edu
Subject: Re: 55mph - calculating HP
Frontal area is the the projected area that is occupied by the car when seen
from the front. So you want the widest and tallest point of the car. the 0.8
factor is to compensate for the fact that your car is not a perfect square
(unless it's a hummer)
Here's a good resource for finding drag and area numbers for cars.
http://www.mayfco.com/tbls.htm
-Peter
On 6/21/07, Dewey, Jody R ATC COMNAVAIRLANT, N422G5G <[EMAIL PROTECTED]> wrote:
> Thanks for the way to calculate it! I have always wanted to find that out.
> BUT, where do you take the height? From just below the windshield? Just
> below the roofline? At what angle do you consider it not to be the front
> anymore?
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> On Behalf Of Phil Marino
> Sent: Thursday, June 21, 2007 12:12
> To: ev@listproc.sjsu.edu
> Subject: RE: 55mph - calculating HP
>
>
>
>
> >From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G"
> ><[EMAIL PROTECTED]>
> >Reply-To: ev@listproc.sjsu.edu
> >To: <ev@listproc.sjsu.edu>
> >Subject: RE: 55mph
> >Date: Thu, 21 Jun 2007 09:06:53 -0400
> >
> >A lot of people don't have that kind of data though. I don't know
> >the Cd of my Nissan or the tire drag coefficient. I do however have
> >the ability to use that general calculation.
>
>
> This reminds me of the story of the guy who was looking for his car keys
> under a streetlight. A friend came along and asked him what he was doing
> there. He said " I dropped my keys on the next block, but there's no
> streetlight down there".
>
>
> If you don't have the data for your car ( and don't want to try to find it on
> the Web) then try this :
>
> Use 0.01 for your tire RR, and use 0.35 for your drag coefficient. For the
> frontal area, measure the car's height and width with a tape measure and
> multiply them together, then multiply that number by 0.8. That will be a
> good approximation. Then you can use the real formula.
>
> You're much better off doing that than using the MOPAR "formula" - it really
> makes no sense at all.
>
>
> Phil Marino
>
>
> >
> >-----Original Message-----
> >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> >On Behalf Of Phil Marino
> >Sent: Thursday, June 21, 2007 8:55
> >To: ev@listproc.sjsu.edu
> >Subject: RE: 55mph
> >
> >
> >Jody
> >
> >This doesn't look like a useful formula to me. It might be close at
> >a particular speed (similar to a stopped watch being exactly correct
> >twice a day), but it would give you huge errors at most speeds.
> >
> >It makes no account of frontal area, Cd, or tire drag coefficient,
> >
> >Even worse, its says that the required horsepower it proportional to
> >the speed. Because air drag dominates at high speed, and the power
> >it soaks up is proportional to the cube of speed, this formula is way off.
> >
> >For example, it would predict that your car would need twice the
> >power to travel at 60 MPH compared to 30 MPH. In most cases, you
> >would need closer to six times the power at double the speed.
> >
> >
> >
> >If you know the frontal area, Cd, tire RR, and weight, Peter's
> >calculations should give you very accurate answers. if you don't
> >know them, take your best guess - and use it anyway.
> >
> >It would still give you much better answers than the MOPAR version.
> >
> >
> >Phil
> >
> >
> >
> > >From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G"
> > ><[EMAIL PROTECTED]>
> > >Reply-To: ev@listproc.sjsu.edu
> > >To: <ev@listproc.sjsu.edu>
> > >Subject: RE: 55mph
> > >Date: Thu, 21 Jun 2007 08:29:37 -0400
> > >
> > >I got this off of a website for MOPARS:
> > >
> > >Engine horsepower required to sustain MPH on level ground (HPs):
> > >
> > >
> > > HPs =
> > > (MPH ÷ 3)
> > > + (WEIGHT ÷ 1,000 × MPH ÷ 10)
> > >
> > >
> > >Note: assumes engine HP must be 2 × the HP required at drive wheels.
> > >Example:
> > >What engine HP is required to sustain 75 MPH in a 3,600 pound vehicle?
> > >
> > >
> > >
> > > HPs =
> > > 75
> > > ÷ 3
> > > + (3,600 ÷ 1,000 × 75 ÷ 10)
> > > _____________________________
> > > 25
> > > + (3.6 × 7.5)
> > > _______________________________________
> > > 52 engine HP
> > >
> > >
> > >-----Original Message-----
> > >From: [EMAIL PROTECTED]
> > >[mailto:[EMAIL PROTECTED] On Behalf Of Peter Gabrielsson
> > >Sent: Thursday, June 21, 2007 2:47
> > >To: ev@listproc.sjsu.edu
> > >Subject: Re: 55mph
> > >
> > >The forces you need to overcome are aerodynamic drag plus the
> > >rolling resistance. (This presumes level ground and no wind)
> > >
> > >The power required to overcome aerodynamic drag = 0.5rho*Cd*A*V*V*V
> > >where rho = density of air = 1.2 kg/m3, Cd = drag coefficient, A =
> > >frontal area of the car in m^2, V = velocity (55mph = 25m/s)
> > >
> > >For my fiat the numbers would be something like: P = 0.5 * 1.2 *
> > >0.4 *
> > >0.6 * 25 * 25 * 25 => 2250W or about 3Hp
> > >
> > >The power required to overcome rolling resistance = V * Crr * g *
> > >m where V = velocity, Crr = coefficient of rolling resistance
> > >(0.006 -
> > >0.01 for lrr tires), g = gravitational constant (9.81m/s^2), m=
> > >mass of car in kg.
> > >
> > >So for a 1200kg (2500lbs) car with marginally low rolling
> > >resistance tires the power needed is 25*0.01*9.81*1200 => 3000W or
> > >about 4Hp
> > >
> > >Total power needed is thus 3+4 = 7Hp at the wheels. In real life
> > >you probably want twice as much at the motor. (due to wind, slopes
> > >& transmission losses)
> > >
> > >Someone check for mistakes, it's late ;)
> > >
> > >
> > >
> > >
> > >On 6/20/07, Rob Hogenmiller <[EMAIL PROTECTED]> wrote:
> > > > What is the mathematical formula to determine how much HP I will
> > > > need to maintain 55mph.
> > > >
> > > > For i.e.
> > > >
> > > > 5,000lbs vehicle x rolling resistance / 10HP= 50mph would
> > > > eventually produce given a long enough run.
> > > >
> > > > (I know that isn't anywhere close to the true formula ust trying
> > > > to get an
> > > > idea)
> > > >
> > > > God bless
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> > >--
> > >www.electric-lemon.com
> > >
> >
> >_________________________________________________________________
> >Who's that on the Red Carpet? Play & win glamorous prizes.
> >http://club.live.com/red_carpet_reveal.aspx?icid=REDCARPET_hotmailtex
> >tlink3
> >
>
> _________________________________________________________________
> Picture this - share your photos and you could win big!
> http://www.GETREALPhotoContest.com?ocid=TXT_TAGHM&loc=us
>
>
--
www.electric-lemon.com
--- End Message ---
--- Begin Message ---
Thanks Victor. The power required did seem kind of low. I got the
frontal area from some website for a similar sized car. I suspect the
0.6 value might have actually been Cd*A.
On 6/21/07, Victor Tikhonov <[EMAIL PROTECTED]> wrote:
Peter,
Everything seem right if you only can fit into a Fiat with
frontal area of 0.6m^2 :-) In reality normal car has about 2m^2,
slick ones like my CRX are 1.7m^2.
Thus, power requirements to ride at 55mph are rather about 8-10kW.
A 0.6 m^2 is frontal area of a slim motorcycle. What kind of Fiat
is this ??
--
Victor
'91 ACRX - something different.
Peter Gabrielsson wrote:
> The forces you need to overcome are aerodynamic drag plus the rolling
> resistance. (This presumes level ground and no wind)
...
> Someone check for mistakes, it's late ;)
--
www.electric-lemon.com
--- End Message ---
--- Begin Message ---
Now here is the question:
My Nissan has a Cd of .300. It has a basically flat front area below the
headlights, aggressive sloped hood, and a pretty good slope of the windshield.
My 96 Geo has a convex front end, more rounded hood, and a sloped windshield.
The Geo looks more aerodynamic but by that chart it has a Cd of .340
By what you said the Geo has a shorter total height, less width overall, and
more streamlined bodywork but has a worse score. What is the true method for
calculating this?
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewey, Jody R
ATC COMNAVAIRLANT, N422G5G
Sent: Thursday, June 21, 2007 13:15
To: ev@listproc.sjsu.edu
Subject: RE: 55mph - calculating HP
Waaay cool site! I found both my 1990 Nissan 240 and my Geo
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Peter Gabrielsson
Sent: Thursday, June 21, 2007 12:58
To: ev@listproc.sjsu.edu
Subject: Re: 55mph - calculating HP
Frontal area is the the projected area that is occupied by the car when seen
from the front. So you want the widest and tallest point of the car. the 0.8
factor is to compensate for the fact that your car is not a perfect square
(unless it's a hummer)
Here's a good resource for finding drag and area numbers for cars.
http://www.mayfco.com/tbls.htm
-Peter
On 6/21/07, Dewey, Jody R ATC COMNAVAIRLANT, N422G5G <[EMAIL PROTECTED]> wrote:
> Thanks for the way to calculate it! I have always wanted to find that out.
> BUT, where do you take the height? From just below the windshield? Just
> below the roofline? At what angle do you consider it not to be the front
> anymore?
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> On Behalf Of Phil Marino
> Sent: Thursday, June 21, 2007 12:12
> To: ev@listproc.sjsu.edu
> Subject: RE: 55mph - calculating HP
>
>
>
>
> >From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G"
> ><[EMAIL PROTECTED]>
> >Reply-To: ev@listproc.sjsu.edu
> >To: <ev@listproc.sjsu.edu>
> >Subject: RE: 55mph
> >Date: Thu, 21 Jun 2007 09:06:53 -0400
> >
> >A lot of people don't have that kind of data though. I don't know
> >the Cd of my Nissan or the tire drag coefficient. I do however have
> >the ability to use that general calculation.
>
>
> This reminds me of the story of the guy who was looking for his car keys
> under a streetlight. A friend came along and asked him what he was doing
> there. He said " I dropped my keys on the next block, but there's no
> streetlight down there".
>
>
> If you don't have the data for your car ( and don't want to try to find it on
> the Web) then try this :
>
> Use 0.01 for your tire RR, and use 0.35 for your drag coefficient. For the
> frontal area, measure the car's height and width with a tape measure and
> multiply them together, then multiply that number by 0.8. That will be a
> good approximation. Then you can use the real formula.
>
> You're much better off doing that than using the MOPAR "formula" - it really
> makes no sense at all.
>
>
> Phil Marino
>
>
> >
> >-----Original Message-----
> >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> >On Behalf Of Phil Marino
> >Sent: Thursday, June 21, 2007 8:55
> >To: ev@listproc.sjsu.edu
> >Subject: RE: 55mph
> >
> >
> >Jody
> >
> >This doesn't look like a useful formula to me. It might be close at
> >a particular speed (similar to a stopped watch being exactly correct
> >twice a day), but it would give you huge errors at most speeds.
> >
> >It makes no account of frontal area, Cd, or tire drag coefficient,
> >
> >Even worse, its says that the required horsepower it proportional to
> >the speed. Because air drag dominates at high speed, and the power
> >it soaks up is proportional to the cube of speed, this formula is way off.
> >
> >For example, it would predict that your car would need twice the
> >power to travel at 60 MPH compared to 30 MPH. In most cases, you
> >would need closer to six times the power at double the speed.
> >
> >
> >
> >If you know the frontal area, Cd, tire RR, and weight, Peter's
> >calculations should give you very accurate answers. if you don't
> >know them, take your best guess - and use it anyway.
> >
> >It would still give you much better answers than the MOPAR version.
> >
> >
> >Phil
> >
> >
> >
> > >From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G"
> > ><[EMAIL PROTECTED]>
> > >Reply-To: ev@listproc.sjsu.edu
> > >To: <ev@listproc.sjsu.edu>
> > >Subject: RE: 55mph
> > >Date: Thu, 21 Jun 2007 08:29:37 -0400
> > >
> > >I got this off of a website for MOPARS:
> > >
> > >Engine horsepower required to sustain MPH on level ground (HPs):
> > >
> > >
> > > HPs =
> > > (MPH ÷ 3)
> > > + (WEIGHT ÷ 1,000 × MPH ÷ 10)
> > >
> > >
> > >Note: assumes engine HP must be 2 × the HP required at drive wheels.
> > >Example:
> > >What engine HP is required to sustain 75 MPH in a 3,600 pound vehicle?
> > >
> > >
> > >
> > > HPs =
> > > 75
> > > ÷ 3
> > > + (3,600 ÷ 1,000 × 75 ÷ 10)
> > > _____________________________
> > > 25
> > > + (3.6 × 7.5)
> > > _______________________________________
> > > 52 engine HP
> > >
> > >
> > >-----Original Message-----
> > >From: [EMAIL PROTECTED]
> > >[mailto:[EMAIL PROTECTED] On Behalf Of Peter Gabrielsson
> > >Sent: Thursday, June 21, 2007 2:47
> > >To: ev@listproc.sjsu.edu
> > >Subject: Re: 55mph
> > >
> > >The forces you need to overcome are aerodynamic drag plus the
> > >rolling resistance. (This presumes level ground and no wind)
> > >
> > >The power required to overcome aerodynamic drag = 0.5rho*Cd*A*V*V*V
> > >where rho = density of air = 1.2 kg/m3, Cd = drag coefficient, A =
> > >frontal area of the car in m^2, V = velocity (55mph = 25m/s)
> > >
> > >For my fiat the numbers would be something like: P = 0.5 * 1.2 *
> > >0.4 *
> > >0.6 * 25 * 25 * 25 => 2250W or about 3Hp
> > >
> > >The power required to overcome rolling resistance = V * Crr * g *
> > >m where V = velocity, Crr = coefficient of rolling resistance
> > >(0.006 -
> > >0.01 for lrr tires), g = gravitational constant (9.81m/s^2), m=
> > >mass of car in kg.
> > >
> > >So for a 1200kg (2500lbs) car with marginally low rolling
> > >resistance tires the power needed is 25*0.01*9.81*1200 => 3000W or
> > >about 4Hp
> > >
> > >Total power needed is thus 3+4 = 7Hp at the wheels. In real life
> > >you probably want twice as much at the motor. (due to wind, slopes
> > >& transmission losses)
> > >
> > >Someone check for mistakes, it's late ;)
> > >
> > >
> > >
> > >
> > >On 6/20/07, Rob Hogenmiller <[EMAIL PROTECTED]> wrote:
> > > > What is the mathematical formula to determine how much HP I will
> > > > need to maintain 55mph.
> > > >
> > > > For i.e.
> > > >
> > > > 5,000lbs vehicle x rolling resistance / 10HP= 50mph would
> > > > eventually produce given a long enough run.
> > > >
> > > > (I know that isn't anywhere close to the true formula ust trying
> > > > to get an
> > > > idea)
> > > >
> > > > God bless
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> > >--
> > >www.electric-lemon.com
> > >
> >
> >_________________________________________________________________
> >Who's that on the Red Carpet? Play & win glamorous prizes.
> >http://club.live.com/red_carpet_reveal.aspx?icid=REDCARPET_hotmailtex
> >tlink3
> >
>
> _________________________________________________________________
> Picture this - share your photos and you could win big!
> http://www.GETREALPhotoContest.com?ocid=TXT_TAGHM&loc=us
>
>
--
www.electric-lemon.com
--- End Message ---
--- Begin Message ---
Cd involves more than just the shape of the front of the object (car, in
this case). It is really an amalgam of several types of drag, such as
parasitic drag (side-view mirrors, radio antennas, etc.), skin-friction
drag (caused by air moving over all the surfaces of the vehicle), base
drag (caused by the shape of the rear of the car, and so on.
It can only be determined accurately by wind-tunnel testing the
vehicle.
--Steve
On Thu, 2007-06-21 at 13:25 -0400, Dewey, Jody R ATC COMNAVAIRLANT,
N422G5G wrote:
> Now here is the question:
>
> My Nissan has a Cd of .300. It has a basically flat front area below the
> headlights, aggressive sloped hood, and a pretty good slope of the
> windshield. My 96 Geo has a convex front end, more rounded hood, and a
> sloped windshield. The Geo looks more aerodynamic but by that chart it has a
> Cd of .340
>
> By what you said the Geo has a shorter total height, less width overall, and
> more streamlined bodywork but has a worse score. What is the true method for
> calculating this?
>
--- End Message ---
--- Begin Message ---
On Thu, 2007-06-21 at 13:25 -0400, Dewey, Jody R ATC COMNAVAIRLANT,
N422G5G wrote:
> Now here is the question:
>
> My Nissan has a Cd of .300. It has a basically flat front area below the
> headlights, aggressive sloped hood, and a pretty good slope of the
> windshield. My 96 Geo has a convex front end, more rounded hood, and a
> sloped windshield. The Geo looks more aerodynamic but by that chart it has a
> Cd of .340
>
> By what you said the Geo has a shorter total height, less width overall, and
> more streamlined bodywork but has a worse score. What is the true method for
> calculating this?
The coefficient of drag doesn't take frontal area into account; it's a
number the defines the fluid friction quality of a particular shape, not
an actual object (which has shape and size):
http://en.wikipedia.org/wiki/Drag_equation
To get the drag force at a given speed, you also need to also include
the frontal area. I'm guessing the Geo's lower frontal area will give it
a lower drag force, even though its Cd is a tad higher (due to its
blockier shape in the back, etc).
--
Christopher Robison
[EMAIL PROTECTED]
http://ohmbre.org <-- 1999 Isuzu Hombre + Z2K + Warp13!
--- End Message ---
--- Begin Message ---
Cd has to be measured, not calculated. It depends on a lot of things not
obvious by inspection, for example, the rear of the car is typically more
influential than the front.
HTH
----- Original Message ----
From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
To: ev@listproc.sjsu.edu
Sent: Thursday, June 21, 2007 1:25:32 PM
Subject: RE: 55mph - calculating HP
Now here is the question:
My Nissan has a Cd of .300. It has a basically flat front area below the
headlights, aggressive sloped hood, and a pretty good slope of the windshield.
My 96 Geo has a convex front end, more rounded hood, and a sloped windshield.
The Geo looks more aerodynamic but by that chart it has a Cd of .340
By what you said the Geo has a shorter total height, less width overall, and
more streamlined bodywork but has a worse score. What is the true method for
calculating this?
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewey, Jody R
ATC COMNAVAIRLANT, N422G5G
Sent: Thursday, June 21, 2007 13:15
To: ev@listproc.sjsu.edu
Subject: RE: 55mph - calculating HP
Waaay cool site! I found both my 1990 Nissan 240 and my Geo
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Peter Gabrielsson
Sent: Thursday, June 21, 2007 12:58
To: ev@listproc.sjsu.edu
Subject: Re: 55mph - calculating HP
Frontal area is the the projected area that is occupied by the car when seen
from the front. So you want the widest and tallest point of the car. the 0.8
factor is to compensate for the fact that your car is not a perfect square
(unless it's a hummer)
Here's a good resource for finding drag and area numbers for cars.
http://www.mayfco.com/tbls.htm
-Peter
On 6/21/07, Dewey, Jody R ATC COMNAVAIRLANT, N422G5G <[EMAIL PROTECTED]> wrote:
> Thanks for the way to calculate it! I have always wanted to find that out.
> BUT, where do you take the height? From just below the windshield? Just
> below the roofline? At what angle do you consider it not to be the front
> anymore?
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> On Behalf Of Phil Marino
> Sent: Thursday, June 21, 2007 12:12
> To: ev@listproc.sjsu.edu
> Subject: RE: 55mph - calculating HP
>
>
>
>
> >From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G"
> ><[EMAIL PROTECTED]>
> >Reply-To: ev@listproc.sjsu.edu
> >To: <ev@listproc.sjsu.edu>
> >Subject: RE: 55mph
> >Date: Thu, 21 Jun 2007 09:06:53 -0400
> >
> >A lot of people don't have that kind of data though. I don't know
> >the Cd of my Nissan or the tire drag coefficient. I do however have
> >the ability to use that general calculation.
>
>
> This reminds me of the story of the guy who was looking for his car keys
> under a streetlight. A friend came along and asked him what he was doing
> there. He said " I dropped my keys on the next block, but there's no
> streetlight down there".
>
>
> If you don't have the data for your car ( and don't want to try to find it on
> the Web) then try this :
>
> Use 0.01 for your tire RR, and use 0.35 for your drag coefficient. For the
> frontal area, measure the car's height and width with a tape measure and
> multiply them together, then multiply that number by 0.8. That will be a
> good approximation. Then you can use the real formula.
>
> You're much better off doing that than using the MOPAR "formula" - it really
> makes no sense at all.
>
>
> Phil Marino
>
>
> >
> >-----Original Message-----
> >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> >On Behalf Of Phil Marino
> >Sent: Thursday, June 21, 2007 8:55
> >To: ev@listproc.sjsu.edu
> >Subject: RE: 55mph
> >
> >
> >Jody
> >
> >This doesn't look like a useful formula to me. It might be close at
> >a particular speed (similar to a stopped watch being exactly correct
> >twice a day), but it would give you huge errors at most speeds.
> >
> >It makes no account of frontal area, Cd, or tire drag coefficient,
> >
> >Even worse, its says that the required horsepower it proportional to
> >the speed. Because air drag dominates at high speed, and the power
> >it soaks up is proportional to the cube of speed, this formula is way off.
> >
> >For example, it would predict that your car would need twice the
> >power to travel at 60 MPH compared to 30 MPH. In most cases, you
> >would need closer to six times the power at double the speed.
> >
> >
> >
> >If you know the frontal area, Cd, tire RR, and weight, Peter's
> >calculations should give you very accurate answers. if you don't
> >know them, take your best guess - and use it anyway.
> >
> >It would still give you much better answers than the MOPAR version.
> >
> >
> >Phil
> >
> >
> >
> > >From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G"
> > ><[EMAIL PROTECTED]>
> > >Reply-To: ev@listproc.sjsu.edu
> > >To: <ev@listproc.sjsu.edu>
> > >Subject: RE: 55mph
> > >Date: Thu, 21 Jun 2007 08:29:37 -0400
> > >
> > >I got this off of a website for MOPARS:
> > >
> > >Engine horsepower required to sustain MPH on level ground (HPs):
> > >
> > >
> > > HPs =
> > > (MPH ÷ 3)
> > > + (WEIGHT ÷ 1,000 × MPH ÷ 10)
> > >
> > >
> > >Note: assumes engine HP must be 2 × the HP required at drive wheels.
> > >Example:
> > >What engine HP is required to sustain 75 MPH in a 3,600 pound vehicle?
> > >
> > >
> > >
> > > HPs =
> > > 75
> > > ÷ 3
> > > + (3,600 ÷ 1,000 × 75 ÷ 10)
> > > _____________________________
> > > 25
> > > + (3.6 × 7.5)
> > > _______________________________________
> > > 52 engine HP
> > >
> > >
> > >-----Original Message-----
> > >From: [EMAIL PROTECTED]
> > >[mailto:[EMAIL PROTECTED] On Behalf Of Peter Gabrielsson
> > >Sent: Thursday, June 21, 2007 2:47
> > >To: ev@listproc.sjsu.edu
> > >Subject: Re: 55mph
> > >
> > >The forces you need to overcome are aerodynamic drag plus the
> > >rolling resistance. (This presumes level ground and no wind)
> > >
> > >The power required to overcome aerodynamic drag = 0.5rho*Cd*A*V*V*V
> > >where rho = density of air = 1.2 kg/m3, Cd = drag coefficient, A =
> > >frontal area of the car in m^2, V = velocity (55mph = 25m/s)
> > >
> > >For my fiat the numbers would be something like: P = 0.5 * 1.2 *
> > >0.4 *
> > >0.6 * 25 * 25 * 25 => 2250W or about 3Hp
> > >
> > >The power required to overcome rolling resistance = V * Crr * g *
> > >m where V = velocity, Crr = coefficient of rolling resistance
> > >(0.006 -
> > >0.01 for lrr tires), g = gravitational constant (9.81m/s^2), m=
> > >mass of car in kg.
> > >
> > >So for a 1200kg (2500lbs) car with marginally low rolling
> > >resistance tires the power needed is 25*0.01*9.81*1200 => 3000W or
> > >about 4Hp
> > >
> > >Total power needed is thus 3+4 = 7Hp at the wheels. In real life
> > >you probably want twice as much at the motor. (due to wind, slopes
> > >& transmission losses)
> > >
> > >Someone check for mistakes, it's late ;)
> > >
> > >
> > >
> > >
> > >On 6/20/07, Rob Hogenmiller <[EMAIL PROTECTED]> wrote:
> > > > What is the mathematical formula to determine how much HP I will
> > > > need to maintain 55mph.
> > > >
> > > > For i.e.
> > > >
> > > > 5,000lbs vehicle x rolling resistance / 10HP= 50mph would
> > > > eventually produce given a long enough run.
> > > >
> > > > (I know that isn't anywhere close to the true formula ust trying
> > > > to get an
> > > > idea)
> > > >
> > > > God bless
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> > >--
> > >www.electric-lemon.com
> > >
> >
> >_________________________________________________________________
> >Who's that on the Red Carpet? Play & win glamorous prizes.
> >http://club.live.com/red_carpet_reveal.aspx?icid=REDCARPET_hotmailtex
> >tlink3
> >
>
> _________________________________________________________________
> Picture this - share your photos and you could win big!
> http://www.GETREALPhotoContest.com?ocid=TXT_TAGHM&loc=us
>
>
--
www.electric-lemon.com
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--- End Message ---
--- Begin Message ---
I tested out my rolling resistance by turning the motor pilot shaft with a
inch pound torque wrench. I connected the socket of the torque wrench to a
hex bolt that was at the end of coupler.
My EV was setting on a dead level smooth concrete floor. I first put the
transmission in neutral and engage a accessory electric clutch that turn all
the accessories units as a normal ICE would have.
I adjusted the torque wrench to 10 inch lbs as a starting point and turn the
motor. The torque wrench did not click, so I lower it to 5 inch lbs and
still did not click. It click at about 1 inch lb.
Now, I shifted the transmission into reverse gear, which gave me a overall
gear ratio of 26:1. It took only 6 inch lbs to move the vehicle.
Shifted it into 1st gear, which is a overall gear ratio 19.5:1 and it only
took 8 inch lbs.
Shifted it into 2nd gear took which is a 13.5:1 gear ratio took 12 inch lbs,
which is the same as 1 foot lb.
In 3rd gear which is 5.57:1 which is the same as the axle gear, took about
25 inch lbs or little over 2 foot lbs.
You can test the rolling resistance by the amount of battery amperes it
takes to start moving and moving at about 5 mph. In this test my battery
ampere range from 3 to 5 amperes.
The tires on this rig are a hard steel face belt that keeps the tire contact
surface more rounded than a standard tire. It is a 8 ply face with a 2 ply
sides, that is allow to deflect rather than the face of the tire which would
increase the resistance.
My EV weighs in at 7200 lbs fully loaded. The load range of the wheels are
rated at 3500 lbs, as well as the rear springs. The load range of the tire
is 2350 lbs at 65 psi which are air up to 65 psi.
Roland
----- Original Message -----
From: "john fisher" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Thursday, June 21, 2007 10:11 AM
Subject: Re: Rolling Resistance - how to measure
> or just tow the car at a slow speed using a spring-scale to measure the
> 'weight' i.e. force
> I'd do it in an empty parking lot, and have a driver in the towed car with
> brake foot ready. ;>)
> your odometer is so inaccurate its worthless IMO. Look into using a GPS or
> an accelerometer like a GTech. or a bicycle
> speedo, after you measure actual wheel diameter.
>
> I'd think, though, just spinning the wheels up on the lift would be good
> enough.
>
> HTH
> JF
>
> Phil Marino wrote:
> >
> >
> >>
> >> This morning I did a test for rolling resistance.
>
>
--- End Message ---
--- Begin Message ---
While I may have made the "Suggestion" it was inspired
by Dennis Berube's Current Eliminators motorized brush
rigging that he has mounted. Plus all the information
I have garnered through this list in the first place
of problem and trials. SO it is really due to
everyone's contributions on this list that inspired
the suggestion. And seeing the issues from the side
lines helped alot. I just hope that from theory to
actual use it pans out to break the Killacycle into a
new record.
--- Bill Dube <[EMAIL PROTECTED]> wrote:
> Actually, Bruce Weisenberger is who suggested that
> we use the Zilla
> series/parallel shift signal to trigger the brush
> timing shift.
>
> Using the series/parallel shift signal to trigger
> the brush timing
> shift really made a lot o sense to me. By making a
> single change in
> timing at a consistent point in the run, you whittle
> the problem down
> to just playing with a couple of settings, at least
> to begin with.
> You pick the starting line timing and the advance
> timing and that is it.
>
> While not perfect, these two timing settings should
> be good enough to
> get what we need. It is also a tractable number of
> variables to
> optimize at the track (or dyno.) If you go with some
> servo that moves
> the timing continuously, you have to build some sort
> of
> multi-dimensional "fuel map" type algorithm to run
> the darned thing.
> It is no doubt "better" but it would be very
> difficult to find the
> best "map." One step between two timing values is
> not at all ideal,
> but at least it is something we can easily do.
>
> Bill Dube'
>
>
> At 08:52 PM 6/20/2007, you wrote:
> >Should have known it would be Bill...
> >>Actually Bill Dube and crew have already set up
> the
> >>motors on Killacycle to do this very thing. Like
> all
> >>untried things we'll have to wait and see how well
> it
> >>works and then improve on it, if it shows promise.
> I
> >>feel there is enough data to show it has merit and
> am
> >>personally eager to see how it all pans out.
>
>
____________________________________________________________________________________
Park yourself in front of a world of choices in alternative vehicles. Visit the
Yahoo! Auto Green Center.
http://autos.yahoo.com/green_center/
--- End Message ---
--- Begin Message ---
When the interior of the car (or even frequently ambient here in
Houston) temp is greater than body temp, and you use a fan, one will
actually heat one's self at a faster rate.
And of course, dress the the weather. Don't try to keep your car in the 60's when it's
>100+ deg.F outside. Use fans or "swamp coolers" to do more of the work.
A swamp cooler will not work in Houston when the humidity is greater
than 75% which is more than 75% of the time. For a swamp cooler to
work it needs lower humidity for evaporative cooling.
Do you really want to use an inefficient automotive belt-driven A/C system,
I could easily switch to a thermoelectric cooler (TEC). I used these
in graduate school for infrared radiometric temperature calibration.
Very robust and solid state. Here's one I might be toying with when
my compressor fails. http://www.melcor.com/ssair.html
Has anyone used TECs for A/C in EVs?
I don't mean to be argumentative about A/C issue. Spend a summer in
Houston without A/C in your car: you end up not wanting to leave the
house. I know energy isn't free and I'm willing to sacrifice some
range for not smelling like a gym locker room when I get to work.
I also don't mean to rip Houston either. The pay is at par with the
rest of the country and living expenses are a fraction of what they
are on the coasts. You just have to put up with five months of
oppressive heat. The other 7 months are great.
Brian
On 6/21/07, Lee Hart <[EMAIL PROTECTED]> wrote:
[snip]
And of course, dress the the weather. Don't try to keep your car in the 60's when it's
>100+ deg.F outside. Use fans or "swamp coolers" to do more of the work.
[snip]
Like A/C, if you start out assuming it is a necessity, then you
unconsciously warp the >whole design to *make* it a necessity.
--
"Those who say it cannot be done should not interrupt the one who is
doing it." -- Chinese proverb
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377
--- End Message ---
--- Begin Message ---
From: Brian Pikkula
> When the interior of the car (or even frequently ambient here in
> Houston) temp is greater than body temp, and you use a fan, one
> will actually heat one's self at a faster rate.
Moving air will still cool you, even when the ambient temperature is above body
temperature, as long as the humidity is less than 100%. How do you think people
survived in jungles before air conditioning?
I've been in Houston, and it certainly can be hot and sticky. But the
statistics aren't as bad as you seem to indicate. The average daily high/low
temperatures and humidities for July (the worst month) are 93/73 deg.F and
93/55%.
>> And of course, dress for the weather. Don't try to keep your car
>> in the 60's when it's >100+ deg.F outside. Use fans or "swamp
>> coolers" to do more of the work.
> A swamp cooler will not work in Houston when the humidity is greater
> than 75% which is more than 75% of the time.
I agree; I wasn't answering you directly, but speaking the the EV list as a
whole.
>> Do you really want to use an inefficient automotive belt-driven
>> A/C system...
> I could easily switch to a thermoelectric cooler (TEC).
These are actually *less* efficient. The most efficient air conditioners that
are commonly available are small home window units, which by law have to meet
energy efficiency standards.
> I don't mean to be argumentative about A/C issue. Spend a summer in
> Houston without A/C in your car: you end up not wanting to leave the
> house.
I know; I've lived in similar climates!
But, I also know that if I live in an air-conditioned house, and work at an
air-conditioned job, and shop in air-conditioned stores, and drive to/from them
in an air-conditiond car, I am living in a isolated man-made environment
completely out of touch with nature. My body never acclimates to the real
climate, and I am trapped indoors.
I found that if I can raise the thermostat, go outside more often, and adapt
myself to the climate, I actually feel better and get more done. But that's
just me.
--
I would not waste my life in friction when it could be turned into momentum. --
Frances Willard
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
thank you,
i´ll continue to try to reach them electronically,
and if that doesn´t work maybe i´ll send them a convential letter overseas
(snail mail)
;)
-------- Original-Nachricht --------
Datum: Thu, 21 Jun 2007 00:10:36 -0800
Von: Mike Willmon <[EMAIL PROTECTED]>
An: ev@listproc.sjsu.edu
Betreff: RE: contacting Electro Automotive (electroauto.com)
> They're there, keep trying, and phoning, and e-mailing this list. They'll
> see it...EVentually. They are a small shop and seem to
> stay pretty busy. They do not discriminate however, they are slow for
> EVerybody equally. A little patience and you'll get
> through. I have been there, and in retrospect it was worth the wait.
>
> Mike,
> Anchorage, Ak.
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> > Behalf Of Florian Schmidt
> > Sent: Wednesday, June 20, 2007 4:22 AM
> > To: ev@listproc.sjsu.edu
> > Subject: contacting Electro Automotive (electroauto.com)
> >
> >
> > does anybody know if the Guys of Electro Automotive have another
> E-Mailadress ? I always get Error Messages when i send
> > an E-Mail to [EMAIL PROTECTED]
> > --
> > Ist Ihr Browser Vista-kompatibel? Jetzt die neuesten
> > Browser-Versionen downloaden: http://www.gmx.net/de/go/browser
> >
> >
--
Psssst! Schon vom neuen GMX MultiMessenger gehört?
Der kanns mit allen: http://www.gmx.net/de/go/multimessenger
--- End Message ---
--- Begin Message ---
Anyone working on the faq for these kind of things?
It could be resent once a week to the list and would be very helpful.
On Wed, 20 Jun 2007 6:56 pm, Rob Hogenmiller wrote:
What is the mathematical formula to determine how much HP I will need
to maintain 55mph.
For i.e.
5,000lbs vehicle x rolling resistance / 10HP= 50mph would eventually
produce given a long enough run.
(I know that isn't anywhere close to the true formula ust trying to get
an idea)
God bless
www.GlobalBoiling.com for daily images about hurricanes, globalwarming
and the melting poles.
www.ElectricQuakes.com daily solar and earthquake images.
--- End Message ---
--- Begin Message ---
Hi Jerry,
thanks for your reply. Let me try to answer your questions and
clarify a couple of things. First off, my batteries do put out 400A when
I ask them to :) and the controller briefly delivers that. But I hope to
get a reasonable lifetime out of the batts (i.e. more than 5000 miles)
and hence do not want to stress them with high amps if I can. 120A is a
conservative limit, where as what I was told the batts would last a long
time.
Here the specs of my car:
- 90V via 15 6V batteries, Varta 160Ah gel
- series wound, 12kw S2 (60min) motor, about 8", 3500rpm at
90V - vehicle weight 2500 lb (so a bit over 1/3rd is
battery weight) - curtis 1221R 375A peak controller
These are notorious for not putting out much power
for any amount of time. You may need a new controller.
- top speed about 50 mph
Do you have a transmission? If so what gear do you
use for hillclimbing? You should always keep the motor at as
high rpm as you can to not lug, overheat it which is what it
is doing it seems. What motor rpm are you using hill
climbing?
I have a 4 speed manual trans. The first speed is locked out, I
usually start in 2nd and use 2nd up to about 30mph, then I need
to shift as the motor wont rev higher even at no load. The motor
is rated at 3300 rpm 84V, I am running it at 90V but as it is a
series wound (probably with compensation windings) I doubt that
it turns much higher due to the higher voltage.
I have lots of smaller hills with inclines of typically up
to 7%. I was told to keep battery amps below 120A to
insure long battery life. I am right now trying to keep
them at least below 160A as a compromise but EVen at this
rate the hillclimbing is more a hillcreeping.
Even gels should put out more amps than that. I hear
Varta's make good EV batts if picked for the right app. It's
unlikely your controller could damage them over than running
them too low.
Oh yes they do. I can get 400A briefly and then drive for a while around
300A which is probably due to the curtis limit kicking in. How bad is
it for 160Ah gel batteries to put out that kind of current?
Most hills
that I worry about are about 2 miles long. In city driving
is not an issue with up to 160A, but on regular streets
where EVery body wants to go 65 I am not comfortable with
going 25 when there is a hill.
What kind of amps does in use on a flat road at what
speed??
30mph - 45A-50A
50mph - 80-100A
Even at 160A my motor heats
up pretty good once I was going a couple of miles. My
first temp sensor is set to 140deg C and turns on the
forced air fan.
Way too high!! It shouldn't be over 180F and should
be under 150F. Your fan should come on early rather than
late. If you hit hills just as you start driving, it should
alway be on always or at least on a 100F thermostat/switch.
You want to cool it between hillclimbs, ect as it takes a
while.
Installed a switch to turn on the fan with the car in low speed
(two speed fan). I will keep in on all the time unless I want to
sneak up on somebody. :)
Motor specs?
84V 12kw S2 (60min), series wound (possibly compound windings)
the motor won't increase RPM over a certain amount, hence I guess
there is some sort of a compound winding as well.
Tire pressure?
50 psi, I am running the tires at the stated pressure limit. They are
also at their weight limit.
Gear lubes??
hmm, don't know. Need to check/replace. What do you suggest?
Thanks
Markus
--- End Message ---