Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-09-2019, 03:25 AM   #41 (permalink)
Duck duck duck
 
RedDevil's Avatar
 
Join Date: Dec 2012
Location: Nieuwegein, the Netherlands
Posts: 3,395

Red Devil - '11 Honda Insight Elegance
Team Honda
90 day: 60.2 mpg (US)

It - '09 Hyundai I10 Active Cool
Team Hyundai
90 day: 30.33 mpg (US)
Thanks: 1,277
Thanked 1,743 Times in 1,129 Posts
Quote:
Originally Posted by Vman455 View Post


This thing has a CD probably <0.10, is as large as a coffin, and races at a blistering 25 km/h. When you scale that up to something that seats 4 and isn't the size of a matchbox, has a significantly higher CD and frontal area, and drives on the highway...400 MPGe is a tough goal to meet. Even the VW XL1 was less than 300 MPGe running on electricity. (Keep in mind that power required to overcome aerodynamic drag increases with the cube of velocity).
The Lightyear is an even more extreme design than the XL1, with hub motors and no engine. So yes, I do believe they can make a car that only uses 75% of the energy an XL1 needs.

Let's do the scaling on that thing though. Make it 3 times as big, it then has 9 times the drag - and it would be longer than the Lightyear 1.
Move it 4 times as fast for 100 km/h; the air resistance would increase 16 fold but friction, drive train losses and rolling resistance would not, so averaging that at 8 times more, multiply by the size factor and we have 72 times more energy to move the scaled up racer at 100 km/h.

That's only a fraction more than the 65 from my assumption, but we'd get there if we scale up by 2.8 times or drive at 94 km/h. That's faster than I usually drive anyway.

__________________
2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.14 Gm or 0.09 MM.


Last edited by RedDevil; 08-09-2019 at 05:15 AM..
  Reply With Quote
The Following 2 Users Say Thank You to RedDevil For This Useful Post:
aerohead (08-10-2019), Xist (08-17-2019)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-09-2019, 04:31 AM   #42 (permalink)
EV convert
 
oil pan 4's Avatar
 
Join Date: Jul 2011
Location: NewMexico (USA)
Posts: 7,493

Sub - '84 Chevy Diesel Suburban C10
SUV
90 day: 19.5 mpg (US)

camaro - '85 Chevy Camaro Z28

Riot - '03 Kia Rio POS
Team Hyundai
90 day: 30.21 mpg (US)

Bug - '01 VW Beetle GLSturbo
90 day: 26.43 mpg (US)

Sub2500 - '86 GMC Suburban C2500
90 day: 11.95 mpg (US)

Snow flake - '11 Nissan Leaf SL
SUV
90 day: 124.63 mpg (US)
Thanks: 177
Thanked 2,338 Times in 1,808 Posts
Has any one made a hub motor for a car that can last as long as a set of tires?
Not very efficient if it has to have 4 hub motors every 10 to 50 thousand miles.
__________________
1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
  Reply With Quote
The Following 2 Users Say Thank You to oil pan 4 For This Useful Post:
aerohead (08-10-2019), Xist (08-17-2019)
Old 08-10-2019, 10:01 AM   #43 (permalink)
EcoModding Lurker
 
Join Date: Jul 2015
Location: Louisiana
Posts: 76
Thanks: 13
Thanked 29 Times in 23 Posts
Quote: "For the first half of 2019 Germany generated more electricity from wind and solar than from coal and nuclear, and Germany traditionally burns, or burned, a lot of coal."


This sounds misleading.

Perhaps it would be illuminating to see the whole spectrum of where German electricity is derived from.

I believe I read that Ms. Merkel has committed Germany to significantly increase its use of Russian natural gas in the future. Perhaps that why they are winding-down their nuclear and coal options.
__________________
  Reply With Quote
Old 08-10-2019, 12:40 PM   #44 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 10,118
Thanks: 15,278
Thanked 5,388 Times in 3,173 Posts
MPGe

Quote:
Originally Posted by Snax View Post
The only way I see it possible to exceed 400 MPGe at this point requires absolutely ideal conditions, very slow speeds, and relying upon the solar panels for full production (which I doubt will ever happen).

Using the specs from their site, the panels provide a maximum of 1.27kW.

So lets just assume that this car can regularly actually sustain 200 MPGe, or 6-ish mi/kWh at 35 MPH. In one hour, the car would obviously travel 35 miles, consuming about 6kWh. Subtract full production of the panels to see about 4.7kWh pack expenditure. Flipping that back to mi/kWh, we get about 7.4. That is still well under 300 MPGe, or most roughly, just under 250 MPGe.

The only ways to get over 400 MPGe with those calcs in mind are to assume one or more things to be true:

1) This car sees significantly over 300 MPGe in typical driving,
2) They are lumping in potential power production from the panels while parked, or
3) It must be driven far slower.

But if we get to add in solar panel production, I am going to take credit for the 5 kW array on my home, the less than 100 miles I typically drive in a week, and always charging at home (when I'm not conducting flawed aerodynamic tests ). The numbers on that cross infinity in all but November and December here in the northern hemisphere.
years ago,I ran some numbers for a 1995 Honda Accord 4-door sedan,with Cd 0.12.At normal 3,100-lb,EPA test weight,normal Honda frontal projected area,and normal 1995-era tire technology,the car would get 100-mpg at 100-km/h.
As an EV,it would get 300-mpge equivalence.You'd be able to squeeze a family of five inside.I used data published by Honda R&D,derived from their series of 'Dream',World Solar Challenge racers,which included all the data for the Accord.
BamZipPow and I are trying to mimic this performance with our pickup trucks,pulling trailers.
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Old 08-10-2019, 04:37 PM   #45 (permalink)
Tyrant-at-large
 
Vman455's Avatar
 
Join Date: Feb 2012
Location: Champaign, IL
Posts: 1,422

Little Red - retired - '05 Honda Civic EX
90 day: 49.03 mpg (US)

Pope Pious the Prius - '13 Toyota Prius Two
Team Toyota
90 day: 55.15 mpg (US)
Thanks: 142
Thanked 1,191 Times in 627 Posts
Quote:
Originally Posted by RedDevil View Post
The Lightyear is an even more extreme design than the XL1, with hub motors and no engine. So yes, I do believe they can make a car that only uses 75% of the energy an XL1 needs.

Let's do the scaling on that thing though. Make it 3 times as big, it then has 9 times the drag - and it would be longer than the Lightyear 1.
Move it 4 times as fast for 100 km/h; the air resistance would increase 16 fold but friction, drive train losses and rolling resistance would not, so averaging that at 8 times more, multiply by the size factor and we have 72 times more energy to move the scaled up racer at 100 km/h.

That's only a fraction more than the 65 from my assumption, but we'd get there if we scale up by 2.8 times or drive at 94 km/h. That's faster than I usually drive anyway.
-Scaling up the body will increase its mass, which will also increase its rolling resistance
-energy required correlates to the cube of velocity for aerodynamic drag force and linearly with velocity for rolling force, since energy is the integral of force. 71 times more drag force (since we're assuming constant rolling resistance between the TUfast and its scaled-up version, even though this would not be true in reality) means an order of magnitude more energy required to overcome that force.
-Then, add in that the Lightyear 1 has a drag coefficient twice that of the TUfast, and more mass (read: rolling resistance) for its size, especially if it's carrying 4 people.
__________________


Last edited by Vman455; 08-10-2019 at 05:00 PM..
  Reply With Quote
The Following 2 Users Say Thank You to Vman455 For This Useful Post:
aerohead (08-14-2019), Xist (08-17-2019)
Old 08-10-2019, 05:52 PM   #46 (permalink)
Duck duck duck
 
RedDevil's Avatar
 
Join Date: Dec 2012
Location: Nieuwegein, the Netherlands
Posts: 3,395

Red Devil - '11 Honda Insight Elegance
Team Honda
90 day: 60.2 mpg (US)

It - '09 Hyundai I10 Active Cool
Team Hyundai
90 day: 30.33 mpg (US)
Thanks: 1,277
Thanked 1,743 Times in 1,129 Posts
Quote:
Originally Posted by Vman455 View Post
-Scaling up the body will increase its mass, which will also increase its rolling resistance
Of course. But not 65 times as much, and not linear to weight. Bigger wheels, relatively less contact area in the moving parts does reduce friction.
Quote:
Originally Posted by Vman455 View Post
-energy required correlates to the cube of velocity for aerodynamic drag force
NO!
We are talking energy efficiency here. To move an object twice as fast the drag quadruples (as it is squared) and the distance covered doubles (as it is linear with speed). So you need 8 times as much power, but you cover twice the distance, hence the economy only suffers to the square.

Call them liars or accept their claim expecting they know their math better than we do. I hinge on the latter.
__________________
2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.14 Gm or 0.09 MM.

  Reply With Quote
The Following 3 Users Say Thank You to RedDevil For This Useful Post:
aerohead (08-14-2019), freebeard (08-10-2019), Xist (08-17-2019)
Old 08-14-2019, 11:02 AM   #47 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 10,118
Thanks: 15,278
Thanked 5,388 Times in 3,173 Posts
math

Quote:
Originally Posted by RedDevil View Post
Of course. But not 65 times as much, and not linear to weight. Bigger wheels, relatively less contact area in the moving parts does reduce friction.

NO!
We are talking energy efficiency here. To move an object twice as fast the drag quadruples (as it is squared) and the distance covered doubles (as it is linear with speed). So you need 8 times as much power, but you cover twice the distance, hence the economy only suffers to the square.

Call them liars or accept their claim expecting they know their math better than we do. I hinge on the latter.
*If they're comparing the two vehicles,side-by-side,at the same velocity,and if the R-R coefficient were the same,from the equations I've got,then the rolling resistance would vary arithmetrically (monotonically?) as a function of (mass)weight.For instance,a doubling of weight would see a doubling of power to overcome rolling resistance,at any given velocity,up to the standing-wave velocity.
*If the R-R coefficient is different (and the skinny tires/wheels could certainly do that!),then that must be accounted for.
*At the same velocity,the vehicle's aerodynamic power requirement,should only vary as a function of the percentage difference in drag-factor (CdA),from one car to the other.A doubling of the CdA would double the aero- power requirement.(we've already accounted for velocity-cubed/power function).
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
The Following User Says Thank You to aerohead For This Useful Post:
Xist (08-17-2019)
Old 08-14-2019, 11:26 AM   #48 (permalink)
EcoModding Newb
 
redpoint5's Avatar
 
Join Date: Aug 2010
Location: Oregon
Posts: 6,125

Acura TSX - '06 Acura TSX
90 day: 28.39 mpg (US)

Lafawnda - '01 Honda CBR600 F4i
90 day: 47.32 mpg (US)

Big Yeller - '98 Dodge Ram 2500 base
90 day: 21.82 mpg (US)

Prius Plug-in - '12 Toyota Prius Plug-in
90 day: 57.64 mpg (US)

Mazda CX-5 - '17 Mazda CX-5 Touring
90 day: 28.88 mpg (US)
Thanks: 2,067
Thanked 2,230 Times in 1,626 Posts
Wind and solar are growing, perhaps faster in Europe, but in the US, the real growth is natural gas.



As sendler is often pointing out, renewables aren't even keeping up with the growth in demand for electricity, let alone beginning to displace non-renewable generation. You've got to cover the growth before you can even begin to reduce total emissions.
__________________
Gas and Electric Vehicle Cost of Ownership Calculator







Give me absolute safety, or give me death!
  Reply With Quote
The Following 3 Users Say Thank You to redpoint5 For This Useful Post:
aerohead (08-14-2019), oil pan 4 (08-14-2019), Xist (08-17-2019)
Old 08-14-2019, 01:00 PM   #49 (permalink)
EV convert
 
oil pan 4's Avatar
 
Join Date: Jul 2011
Location: NewMexico (USA)
Posts: 7,493

Sub - '84 Chevy Diesel Suburban C10
SUV
90 day: 19.5 mpg (US)

camaro - '85 Chevy Camaro Z28

Riot - '03 Kia Rio POS
Team Hyundai
90 day: 30.21 mpg (US)

Bug - '01 VW Beetle GLSturbo
90 day: 26.43 mpg (US)

Sub2500 - '86 GMC Suburban C2500
90 day: 11.95 mpg (US)

Snow flake - '11 Nissan Leaf SL
SUV
90 day: 124.63 mpg (US)
Thanks: 177
Thanked 2,338 Times in 1,808 Posts
I'm good with waiting and finding out.
They have promised hub motors that don't exist and efficiency no one thinks is possible.
At this point I will be surprised if they build it at all.
I'm expecting a more pedestrian version that doesn't use hub motors and gets the equivalent of less than 300 mpg when a normal person drives it outside in the real world.
The 400mpge number will likely remain a parlor trick that can't be reproduced outside a controlled environment.
__________________
1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
  Reply With Quote
The Following User Says Thank You to oil pan 4 For This Useful Post:
Xist (08-17-2019)
Old 08-15-2019, 01:10 PM   #50 (permalink)
Master EcoModder
 
NeilBlanchard's Avatar
 
Join Date: May 2008
Location: Maynard, MA Eaarth
Posts: 7,551

Mica Blue - '05 Scion xA RS 2.0
Team Toyota
90 day: 42.48 mpg (US)

Forest - '15 Nissan Leaf S
Team Nissan
90 day: 156.46 mpg (US)

Number 7 - '15 VW e-Golf SEL
TEAM VW AUDI Group
90 day: 155.81 mpg (US)
Thanks: 2,899
Thanked 2,578 Times in 1,603 Posts
The hub motors they used in the STELLA were over 98% efficient.

__________________
Sincerely, Neil

http://neilblanchard.blogspot.com/
  Reply With Quote
The Following User Says Thank You to NeilBlanchard For This Useful Post:
aerohead (08-17-2019)
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com