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IssacZachary
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Re: Aeromod nissan leaf improved aerodynamics increased range

Mon Mar 06, 2017 9:13 am

lorenfb wrote:While traveling on freeways (50% of driving) at 60 - 65 MPH in the past, my overall average was about 4.5 miles/kWh.
Presently, my freeway speeds are 50 - 52 MPH. My overall average is now 5.1 miles/kWh. That's about a 13% improvement
without any aero mods, and how simple was that!


Yes! The easiest "aeromod" is to simply reduce speed. If you drive at 12mph you'll be able to go very far.

But let's say you could reduce the aerodynamic drag to a coefficient of around 0.17Cd. The result would be that going 65mph you'd get the efficiency of going 45mph without aeromods.

With aeromods you also benefit if you use climate control because going faster you would use the climate control for less time.

The only thing I see in this thread, though, is that everyone seems to go about aeromodding backwards. The focus usually goes towards the front of the vehicle. Not that there isn't room for improvement in the front, but the main improvements to be made are in the rear of a vehicle.
Image
As you can see, the distinctive tear drop shape can have a barely noticeable 0.05Cd going forwards or a terrible 0.34Cd going backwards. That's nearly 8 times the amount of air drag!

The few times I've seen cars put in a wind tunnel backwards, that's almost always when they are more aerodynamic. The Leaf is similar in design to other cars. The sloping part is in the front, and the blunt end is in the rear. Aerodynamically it should be the other way around. But we aren't going to be going down the highway backwards now are we. Others have overcome this by simply adding and airplane or boat tail to the rear of the vehicle. A classic example is the AeroCivic, which cut it's drag in half, and the biggest improvement wasn't the wheel spats or blocking off the front grill. It was the tail that was attached to it.

AeroCivic wrote:The biggest one, both in strange looks received and on its effect in improving my gas mileage is the boat tail. This is the tapered back end of my car that resembles the back of an aircraft fuselage. This eliminates the recirculating, low-pressure eddy that forms behind "normal" cars and that act to slow them down. This eddy is also responsible for the dirt that accumulates on a car's backside and allows a closely following car to improve its mileage by drafting. As a result of my boat tail, the back end of my car remains clean and anybody drafting me would gain no mileage benefits.


Image
2013 SL 45,000 miles.
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The Nissan Leaf is the fourth best long distance car for highway driving. >>Best Long Distance Cars<<

VitaminJ
Posts: 357
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Re: Aeromod nissan leaf improved aerodynamics increased range

Mon Mar 06, 2017 9:49 am

Brenthasty has a kammaback like that on his Leaf for a couple years now. Claims 50% improvement. His execution is the best I've seen, minimal material to create the most effect. It's also clear so it's as unobtrusive as possible. That's a little bit too much for me, I want the car to look as stock as possible and no major mods because I want to sell it in a couple years. His is the one to copy if you're game yourself.


Image


More pictures at his blog:
http://fireplacefurnaces.blogspot.com/2 ... e.html?m=1

Brenthasty wrote:http://ecomodder.com/forum/em-fuel-log.php?vehicleid=9542

Long term results are a 50% improvement!

This make a big difference on long road trips .
Reduces time spent at Quick Charge stations .
Reduces loss of battery capacity over time due to reduced sustained power draw from the traction pack.

Had you tried it a year ago you would already know....
2013 Ocean Blue SV w/ QC and LED
- +0.2 mi/kwh Aeromods
- Leaf Box
- 2lb 5Ah LiFe 12v battery

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IssacZachary
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Re: Aeromod nissan leaf improved aerodynamics increased range

Mon Mar 06, 2017 1:45 pm

VitaminJ wrote:Brenthasty has a kammaback like that on his Leaf for a couple years now...


Thanks! That's awesome!
Last edited by IssacZachary on Mon Mar 06, 2017 2:23 pm, edited 1 time in total.
2013 SL 45,000 miles.
12 bars until 44,300 miles on June 2, 2017. :D
11 bars current. :)
The Nissan Leaf is the fourth best long distance car for highway driving. >>Best Long Distance Cars<<

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IssacZachary
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Re: Aeromod nissan leaf improved aerodynamics increased range

Mon Mar 06, 2017 2:22 pm

lorenfb wrote:The energy consumed by a vehicle's drag resistance as it moves thru the air is:

Energy = K A V^2, where K is the coefficient of drag, A is the frontal area of the vehicle, V is the velocity (it's squared)
of the vehicle.


Basically, but you forgot to add the density of air in the equation. Energy = V^2 Cd A D, where Cd is the coefficient of drag, A is the frontal area, V velocity and D is the density of air (or other fluid. Just think, when we get to travel to Mars we'll be able to drive Leaf's there. Or make it submersible and drive underwater??)

lorenfb wrote:As can be noted from above, the vehicle's speed does affect both the rolling resistance energy loss and the drag
energy loss.

That's not true. The power to combat rolling resistance increases with speed, but the amount of energy used per mile doesn't hardly increase. If it takes 16 miles per kilowatt-hour to push against rolling resistance at 5mph it will be basically the same at 80mph. Aerodynamic drag does use more energy per mile with greater speed. The amount of energy increases exponentially too. On most vehicles, the area where both use about the same about of energy per mile is around 25 to 30mph.

Image

If you were to figure power to overcome aerodynamic drag you would use the same equation, only it would be V^3.

Power = = V^3 Cd A D.

http://ecomodder.com/forum/tool-aero-rolling-resistance.php
2013 SL 45,000 miles.
12 bars until 44,300 miles on June 2, 2017. :D
11 bars current. :)
The Nissan Leaf is the fourth best long distance car for highway driving. >>Best Long Distance Cars<<

DesertSprings
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Leaf Number: 319100
Location: Southern California

Re: Aeromod nissan leaf improved aerodynamics increased range

Mon Mar 06, 2017 5:33 pm

VitaminJ wrote:Brenthasty has a kammaback like that on his Leaf for a couple years now. Claims 50% improvement. His execution is the best I've seen, minimal material to create the most effect. It's also clear so it's as unobtrusive as possible. That's a little bit too much for me, I want the car to look as stock as possible and no major mods because I want to sell it in a couple years. His is the one to copy if you're game yourself.


I would love something like that which could be removed without damaging the car. Is there a post anywhere with either where to buy or instructions on how to make?

lorenfb
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Re: Aeromod nissan leaf improved aerodynamics increased range

Wed Mar 08, 2017 10:37 am

lorenfb wrote:The energy consumed by a vehicle's drag resistance as it moves thru the air is:

Energy = K A V^2, where K is the coefficient of drag, A is the frontal area of the vehicle, V is the velocity (it's squared)
of the vehicle.


Yes, it's (the equation) power and not energy (Energy = Integral (Power dt)) and V is cubed, i.e. my typos.

lorenfb wrote:As can be noted from above, the vehicle's speed does affect both the rolling resistance energy loss and the drag
energy loss.


The above statement is correct.

IssacZachary wrote:The power to combat rolling resistance increases with speed,


Yes, that's correct! The energy loss is; Integral (Power dt).

VitaminJ
Posts: 357
Joined: Tue Jan 03, 2017 11:46 am
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Location: Morrison, CO
Contact: YouTube

Re: Aeromod nissan leaf improved aerodynamics increased range

Wed Mar 08, 2017 11:00 am

I found some old pictures of my older Honda that I aeromodded back in the day. If someone doesn't want to buy factory mudflaps you can get 99% of the same results with a simple tire airdam like this made from plastic sheet:

Image

Image

Image


DesertSprings wrote:I would love something like that which could be removed without damaging the car. Is there a post anywhere with either where to buy or instructions on how to make?

I can only point you to his posts in this thread and the link to his blog that I shared.
2013 Ocean Blue SV w/ QC and LED
- +0.2 mi/kwh Aeromods
- Leaf Box
- 2lb 5Ah LiFe 12v battery

estomax
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Location: Seattle

Re: Aeromod nissan leaf improved aerodynamics increased range

Fri Mar 10, 2017 3:00 pm

wow the kammback that brenthasty did is very nice! i would not mind rocking one of those for bumping my freeway efficiency
2013 Leaf SL Premium
27k, 93% SoH, 2/17
32k, 96% SoH, 6/17

DesertSprings
Posts: 149
Joined: Wed Dec 03, 2014 4:40 pm
Delivery Date: 21 Dec 2014
Leaf Number: 319100
Location: Southern California

Re: Aeromod nissan leaf improved aerodynamics increased range

Tue Mar 14, 2017 12:39 pm

estomax wrote:wow the kammback that brenthasty did is very nice! i would not mind rocking one of those for bumping my freeway efficiency


Yup, I'd love to get one.

LeftieBiker
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Re: Aeromod nissan leaf improved aerodynamics increased range

Tue Mar 14, 2017 3:09 pm

That Kammback would sell well as an aftermarket Leaf accessory.
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

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