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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 07-12-2012, 06:24 AM   #1 (permalink)
EcoModding Lurker
 
Join Date: Jul 2012
Location: UK
Posts: 13
Thanks: 0
Thanked 0 Times in 0 Posts
Drag effects at low speeds?

Me and a group of people are making a small car which is powered by an electric motor for a race, I am having a hard time deciding on a design for the bodywork, after researching I thought the best design would be a tear drop since many say it has the lowest drag coefficient of any natural shape, what are your thoughts on this?

Some extra information: The cars maximum speed will probably not go over 30mph, the front and rear wheels have to be in-line.

An additional question, we are using bike tyres for the wheels on the vehicle, is it worth covering these up or at such low speeds will the drag not be noticeable?

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 07-12-2012, 09:08 AM   #2 (permalink)
Master EcoModder
 
NeilBlanchard's Avatar
 
Join Date: May 2008
Location: Maynard, MA Eaarth
Posts: 7,907

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: 3,475
Thanked 2,950 Times in 1,844 Posts
Think of riding a bicycle at 20mph; let alone at 30mph. Drag is significant, and the churning wheels also add drag. Look at the performance of a velomobile vs a bicycle. The only time when the weight of the body is a greater penalty than the lower drag is up long steep hills.
__________________
Sincerely, Neil

http://neilblanchard.blogspot.com/
  Reply With Quote
Old 07-12-2012, 10:08 AM   #3 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
Thanks: 4,058
Thanked 6,957 Times in 3,602 Posts
You can also run the numbers yourself: aero & rolling drag calculator
__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 07-12-2012, 10:16 AM   #4 (permalink)
Cyborg ECU
 
California98Civic's Avatar
 
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,299

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 66.42 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
Thanks: 2,373
Thanked 2,172 Times in 1,469 Posts
Quote:
Originally Posted by examorph View Post
Me and a group of people are making a small car which is powered by an electric motor for a race, I am having a hard time deciding on a design for the bodywork, after researching I thought the best design would be a tear drop since many say it has the lowest drag coefficient of any natural shape, what are your thoughts on this?
Look up "the template" thread here on EM. I would imagine a really good and not too difficult design would be a version of the 1930s Schlorwagen's shape, which resembles a "tear-drop" a little, adapted with a trailing edge that is a bit more like the template, which also resembles the tear drop a little. Get a copy of Hucho's book on the "Aerodynamics of Road Vehicles" through your library's inter library loan program, or buy it ($$$). For fun and design ideas, spend some time on the thread called "interesting aerodynamic vehicles." It features pics of classic and little known vehicles almost entirely. The Schorwagen is on it too. Good luck!
__________________
See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.




Last edited by California98Civic; 07-12-2012 at 11:43 AM..
  Reply With Quote
Old 07-12-2012, 11:30 AM   #5 (permalink)
Master EcoModder
 
Sven7's Avatar
 
Join Date: Aug 2011
Location: Warren, MI
Posts: 2,456

Boo Radley - '65 Ford F100
90 day: 13.28 mpg (US)
Thanks: 782
Thanked 667 Times in 409 Posts
Instead of the Schlorwagen I would imagine something like this:


But following the template where possible. Full boat tail. Full under body covering. Enclosed wheels (unless you'll be making tight turns)
__________________
He gave me a dollar. A blood-soaked dollar.
I cannot get the spot out but it's okay; It still works in the store
  Reply With Quote
Old 07-13-2012, 02:24 AM   #6 (permalink)
Master EcoModder
 
euromodder's Avatar
 
Join Date: Jul 2010
Location: Belgium
Posts: 4,683

The SCUD - '15 Fiat Scudo L2
Thanks: 178
Thanked 652 Times in 516 Posts
Quote:
Originally Posted by examorph View Post
An additional question, we are using bike tyres for the wheels on the vehicle, is it worth covering these up
Definitely.
The spokes add a lot of drag.
On many Velomobiles, the spokes get covered with a circular cloth so the shape is smooth.

Keep weight low, and use narrow bike race wheels and tyres pumped up to their advertised limit for low rolling resistance.
__________________
Strayed to the Dark Diesel Side

  Reply With Quote
Old 07-13-2012, 03:58 AM   #7 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,762

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,585
Thanked 3,555 Times in 2,218 Posts
I would look to the HPV crowd for the best examples of things to copy.
__________________


  Reply With Quote
Old 07-13-2012, 10:30 AM   #8 (permalink)
Master EcoModder
 
euromodder's Avatar
 
Join Date: Jul 2010
Location: Belgium
Posts: 4,683

The SCUD - '15 Fiat Scudo L2
Thanks: 178
Thanked 652 Times in 516 Posts
Quote:
Originally Posted by Frank Lee View Post
I would look to the HPV crowd for the best examples of things to copy.
Yeah, having to power something yourself tends to make people more inventive at reducing their workload
__________________
Strayed to the Dark Diesel Side

  Reply With Quote
Old 07-13-2012, 12:57 PM   #9 (permalink)
Do more with less
 
Join Date: Jul 2010
Location: North Eastern Missouri
Posts: 930

OD - '05 Ford Econoline
90 day: 18.64 mpg (US)

Joetta - '86 Volkswagen Jetta Turbo Oil Burner
TEAM VW AUDI Group
90 day: 49.71 mpg (US)

Benzilla - '85 Mercedes Benz 300D
90 day: 28.08 mpg (US)
Thanks: 66
Thanked 177 Times in 112 Posts
I have two running HPV's
This one takes about 100 watts of power at 30 mph


This one is a tricycle.


There are lots of photos of my liners at: veloliner.com
__________________
“The further a society drifts from the truth, the more it will hate those that speak it.” George Orwell

“Before a standing army can rule, the people must be disarmed; as they are in almost every kingdom in Europe.

The supreme power in America cannot enforce unjust laws by the sword; because the whole body of the people are armed.”

Noah Webster, 1787
  Reply With Quote
Old 07-13-2012, 06:13 PM   #10 (permalink)
Master EcoModder
 
Join Date: Feb 2010
Location: Elmira, NY
Posts: 1,781
Thanks: 319
Thanked 355 Times in 297 Posts
Even a simlpe touring fairing on my city bike improved my cruise speed from 11 mph to 14 mph. Every bit helps.

  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com