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

Now available from EcoModder: ScanGauge II fuel economy gauge.  Click for details.  

Reply  Post New Thread
 
Submit Tools LinkBack (79) Thread Tools
Old 10-22-2009, 10:12 AM   #21 (permalink)
Master EcoModder
 
Join Date: Nov 2008
Location: 18603, USA
Posts: 263

The Crimson Crawler - '04 Elantra GLS
90 day: 32.14 mpg (US)
Thanks: 16
Thanked 5 Times in 5 Posts
Could you make it so that you open the hatch to be the "top" of the boattail, and the rest of it extends/unfurls from inside the car?


(Support Ecomodder.com & get rid of these annoying ads!)      
 
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
  Reply With Quote
Old 10-22-2009, 01:32 PM   #22 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 9,735

Blackfly - '98 Metro
Team Metro
90 day: 78.84 mpg (US)

ForkenSwift - '92 Metro EV
90 day: 81.72 mpg (US)
Thanks: 90
Thanked 273 Times in 172 Posts
Unfortunately not. The top of the hatch is actually about 6 inches of the end of the roof. Opening it even part way increases frontal area and hammers Cd.



Semi-related: Video: Illustrating the Vast Importance of Aerodynamics (open hatchback experiment) - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com
__________________
Latest project:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Latest test:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
- fuel efficiency info for Geo Metro owners

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
- electric car conversion on a beer budget
  Reply With Quote
Old 10-22-2009, 02:09 PM   #23 (permalink)
PSmodder lurker
 
botsapper's Avatar
 
Join Date: Jan 2009
Location: Chino
Posts: 155
Thanks: 0
Thanked 15 Times in 9 Posts
Bubble butt



Here's another view of the removeable tail. The clear/body color PVC panels welded into a rear-body conforming airfoil. The inflatable would have multiple high pressure tube spars either longitudinally or transverse (interestingly the transverse 'bumps' offer some aero benefits, Mythbuster testing?)
The temporary structure could be held down with straps & there is a rigid spar coming from the trailer hitch, holding the signal harness, plate & rear light assemblies. It also tucks in & tidy up the inflatable tube ends.
At the end of the day, it could also serve as the children's slide on the front lawn.
  Reply With Quote
Old 10-24-2009, 04:22 PM   #24 (permalink)
Master EcoModder
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 2,133
Thanks: 180
Thanked 112 Times in 78 Posts
bowling for fuel

Quote:
Originally Posted by botsapper View Post


Here's another view of the removeable tail. The clear/body color PVC panels welded into a rear-body conforming airfoil. The inflatable would have multiple high pressure tube spars either longitudinally or transverse (interestingly the transverse 'bumps' offer some aero benefits, Mythbuster testing?)
The temporary structure could be held down with straps & there is a rigid spar coming from the trailer hitch, holding the signal harness, plate & rear light assemblies. It also tucks in & tidy up the inflatable tube ends.
At the end of the day, it could also serve as the children's slide on the front lawn.
I'd set up bowling pins on the curb and then see how many can be knocked over with a left turn!
Wow,the imagery is just too good!
I do think maybe Kamm has a point with "practical" length issues.Something this long might want to be half car/half trailer.I'm to squeemish to attempt something that radical in pure cantilever.Not sure what a strong momentary sidewind gust might do.
We do need an EcoModder wind tunnel!
  Reply With Quote
Old 10-24-2009, 06:02 PM   #25 (permalink)
EcoModding Apprentice
 
Bicycle Bob's Avatar
 
Join Date: May 2008
Location: N. Saskatchewan, CA
Posts: 960

Appliance White - '93 Metro 4-Dr. Auto
Last 3: 42.35 mpg (US)

Stealth RV - '91 Sprint Base
Thanks: 24
Thanked 67 Times in 57 Posts
The area swept by a turning car is symmetrical fore and aft of the rear axle, so overhang, especially if tapered, will not hit stuff.
Most cars can use more tail area for crosswind stability. The center of "lift" is usually about 25% of the way back, since the front is redirecting the air, while the center of mass falls naturally around 50% back. The tail does generate more side force, but it is on the back axle, which has traction that otherwise makes the front end wander. Even with long tails, several streamliners have added a tail fin for stability. More side force, within the ability of the chassis to support it, may even give a boost by working as a wing-sail.
  Reply With Quote
The Following User Says Thank You to Bicycle Bob For This Useful Post:
aerohead (10-28-2009)
Old 10-24-2009, 06:04 PM   #26 (permalink)
Master EcoModder
 
Old Tele man's Avatar
 
Join Date: Jul 2009
Location: Tucson, AZ
Posts: 998

Vibe - '09 Vibe Base (2ZR-FE)
90 day: 35.32 mpg (US)
Thanks: 10
Thanked 43 Times in 40 Posts
...pardon my simplistic analogy, but it sure "looks" like a really bad case of the "...tail waggging the dog..." situation to me.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
  Reply With Quote
Old 10-24-2009, 06:10 PM   #27 (permalink)
Master EcoModder
 
Join Date: Nov 2008
Location: Madison AL
Posts: 969

Jeep Offspring - '97 MPV Allsport 2wd
90 day: 19.05 mpg (US)

The Geo - '93 Metro
Team Metro
90 day: 46.86 mpg (US)

Truckwez - '04 Dakota SLT
Thanks: 24
Thanked 26 Times in 24 Posts
Quote:
Originally Posted by Old Tele man View Post
...pardon my simplistic analogy, but it sure "looks" like a really bad case of the "...tail waggging the dog..." situation to me.
Not if you ran some strings to opposing sides of the car, that hooked on the inside of the balloon.

i.e. top left hooks to bottom right
  Reply With Quote
Old 10-24-2009, 09:58 PM   #28 (permalink)
Left Lane Ecodriver
 
Join Date: Aug 2008
Location: Buffalo, NY, USA
Posts: 936

Zombie Insight - '00 Insight MT
Team Honda
90 day: 55.13 mpg (US)
Thanks: 18
Thanked 58 Times in 42 Posts
With something as useful and beautiful as this, why would you want it removable?

Okay, I suppose it would interfere with your ability to load akward cargo and parallel park. But if you drop the requirement that it be able to be stored inside the Metro, it becomes easier to design and build, since you can use a single rigid frame. Storable in the garage is almost as good. You'd use the boattail on road trips, and leave it at home for commuting.

@Botsapper: That's a very nice render. But if you taper the sides, bottom, and top at the same angle, you preserve attached flow with shorter overall length. Actually, with the Metro taillamps being almost half as wide as the rear of the car (based on counting driveway tiles), you probably want a square rear truncation, with the license plate mounted above or below the taillamps.

MetroMPG: How long do you think you're going to make the boattail?
  Reply With Quote
Old 10-24-2009, 10:23 PM   #29 (permalink)
EcoModding Apprentice
 
Bicycle Bob's Avatar
 
Join Date: May 2008
Location: N. Saskatchewan, CA
Posts: 960

Appliance White - '93 Metro 4-Dr. Auto
Last 3: 42.35 mpg (US)

Stealth RV - '91 Sprint Base
Thanks: 24
Thanked 67 Times in 57 Posts
The bottom is not so well supplied with air, even with a great belly pan and rounded. 4 degrees on the belly pan is usually as conservative as 15 deg on the top and sides. If the tapers were continued to a point at the back, it should be only slightly higher than the stagnation point at the front. A bit of rake will help cancel the lift and induced drag if the air goes over the top faster than underneath.
  Reply With Quote
Old 10-24-2009, 10:39 PM   #30 (permalink)
EcoModding Apprentice
 
Join Date: Dec 2008
Location: Milton, WI
Posts: 191

AlienMobile - '00 Insight
90 day: 67.7 mpg (US)
Thanks: 6
Thanked 52 Times in 22 Posts
Quote:
Originally Posted by Bicycle Bob View Post
The bottom is not so well supplied with air, even with a great belly pan and rounded. 4 degrees on the belly pan is usually as conservative as 15 deg on the top and sides.
Nice to hear from you again!

If I am reading what you have said about the relative lack of air on underside of the vehicle compared to the sides and top, it would seem that you could conclude that the taper on the underside of the aerocivic is too steep.

I remember reading in that thread somewhere, that you asked Mike if he had performed tuft testing in that location. How much higher can the 4° go before air detachment would be a concern in this location?

Jim.
  Reply With Quote
Reply  Post New Thread

Tags
boat tail, testing

Thread Tools


LinkBacks (?)
LinkBack to this Thread: http://ecomodder.com/forum/showthread.php/project-geo-metro-boat-tail-prototype-15-mpg-10691.html
Posted By For Type Date
How To: Paritial Kammback This thread Refback Yesterday 09:00 PM
2010 January 07 | The Entertainment Blog This thread Refback Yesterday 03:00 PM
Fuel Economy | Autopia | Wired.com This thread Refback 03-06-2010 06:57 AM
La Cacharrería: un blog de tecnología diferente - Part 2 This thread Refback 02-18-2010 11:41 AM
S2KI - S2000 Forums -> impressive s2k mpg! This thread Refback 02-04-2010 01:28 AM
cars Archives : TreeHugger This thread Refback 01-30-2010 11:58 AM
Transportation-buildaroo.com This thread Refback 01-20-2010 03:54 AM
Kawasaki Triples WorldWide • View topic - Bike maintaining Tips .... This thread Refback 01-18-2010 12:53 PM
Anno | Motorcafè il blog dei motociclisti dalla mente aperta This thread Refback 01-16-2010 11:36 AM
????, ???? : monogocoro ????? This thread Refback 01-12-2010 09:26 PM
Slashdot Submission | Aerodynamic tail on Geo Metro boosts MPG 15% This thread Refback 01-12-2010 06:13 PM
Slashdot - News for nerds, stuff that matters This thread Refback 01-12-2010 05:57 PM
Autopia - Part 5 This thread Refback 01-12-2010 04:47 PM
Cool Cars | Autopia | Wired.com This thread Refback 01-11-2010 03:28 PM
????, ?????(??) : monogocoro ????? This thread Refback 01-10-2010 12:04 AM
????? ??????????? ?????? ????? • ???????? ???? - ???????(????) This thread Refback 01-09-2010 09:03 AM
Ingeniøren Mobil This thread Refback 01-09-2010 05:27 AM
Spar 15 procent med en grim hale - Motorbloggen | Ingeniøren This thread Refback 01-08-2010 04:04 AM
Difícil de aparcar, sí; ¡pero gasta como un mechero! | La Cacharrería This thread Refback 01-07-2010 01:34 PM
monogocoro ????? - Part 4 This thread Refback 01-07-2010 09:58 AM
Motorcafè il blog dei motociclisti dalla mente aperta - Part 2 This thread Refback 01-07-2010 09:00 AM
Chuck Squatriglia | Autopia | Wired.com This thread Refback 01-06-2010 07:25 PM
Project: Geo Metro boat tail prototype - 15% MPG improvement @ 90 kph / 56 mph - Topic Powered by Social Strata This thread Refback 01-06-2010 06:00 PM
Design & Architecture Archives : TreeHugger This thread Refback 01-04-2010 11:58 PM
insidE of jaXonz This thread Refback 01-04-2010 10:02 PM
Buzz Punching: "Boat Tail" Increases Car's Miles Per Gallon by 15.1% This thread Refback 01-04-2010 09:47 PM
Guy Adds Boat Tail to Car, Increases MPG by 15.1% : TreeHugger This thread Refback 01-04-2010 02:28 PM
TreeHugger This thread Refback 01-04-2010 02:18 PM
Cars & Transportation Archives : TreeHugger This thread Refback 01-04-2010 01:16 PM
Items Tag RIT Make Club Idea Stream This thread Refback 01-04-2010 12:16 PM
Oszcz?dzaj paliwo z aerodynamicznym ogonem! (wideo) | Gad?etomania.pl This thread Refback 01-04-2010 11:14 AM
Teemu's planet This thread Refback 01-02-2010 09:15 AM
Bike Hugger This thread Refback 01-02-2010 07:55 AM
Daily DIY Network - Science Projects Plans Guides Blog Archive MPG boosting tail cone This thread Refback 01-02-2010 12:08 AM
Daily DIY Network - Science Projects Plans Guides This thread Refback 01-01-2010 07:22 PM
Make: Online This thread Refback 01-01-2010 07:11 PM
Autopia - Part 2 This thread Refback 01-01-2010 07:06 PM
siani_hedgehog's Friends This thread Refback 01-01-2010 05:09 PM
Make: Online : MPG boosting tail cone This thread Refback 01-01-2010 04:21 PM
Make: Online This thread Refback 01-01-2010 04:13 PM
A New Years Resolution - Bike Hugger This thread Refback 01-01-2010 11:17 AM
Firefly efficiency mods - MetroMPG.com This thread Refback 01-01-2010 01:42 AM
green hacks - Hack a Day This thread Refback 12-31-2009 03:02 PM
FFFFOUND! | flea-boat-tail-collage.jpg (JPEG Image, 500x363 pixels) This thread Refback 12-31-2009 09:56 AM
PWnT 2009 - (P)ost (W)hori(n)' (T)hread - Page 10598 - CarForums.net - Automotive Chat Forum This thread Refback 12-30-2009 07:08 PM
GeenStijl : Sneller, Scherper, Beter (maar eigenlijk komt hier een betere tagline) This thread Refback 12-30-2009 02:01 PM
Enterprising DIYer adds boat tail to Pontiac Firefly to boost mileage — Autoblog Green This thread Refback 12-29-2009 09:01 PM
Jalopnik - Attention, Greenies: Your Geo Metro Needs A Boattail This thread Refback 12-29-2009 08:46 PM
Interesting New Products and Inventions: Boat Tail improves Mileage This thread Refback 12-29-2009 07:25 PM
Autoblog Green — We Obsessively Cover The Green Scene This thread Refback 12-29-2009 07:09 PM
Attention, Greenies: Your Geo Metro Needs A Boattail - hypermiling - Jalopnik This thread Refback 12-29-2009 05:17 PM
Jalopnik: Obsessed With The Cult Of Cars This thread Refback 12-29-2009 05:16 PM
YouTube - EcoModderDOTcom's Channel This thread Refback 12-29-2009 04:19 PM
GeenStijl This thread Refback 12-29-2009 02:19 PM
GeenStijl : Tendentieus, ongefundeerd en nodeloos kwetsend This thread Refback 12-29-2009 11:41 AM
GeenStijl : Tendentieus, ongefundeerd en nodeloos kwetsend This thread Refback 12-29-2009 10:46 AM
GeenStijl : 15% zuiniger rijden met iedere auto! This thread Refback 12-29-2009 10:35 AM
GeenStijl This thread Refback 12-29-2009 10:16 AM
GeenStijl : 15% Zuinig rijden met iedere auto! This thread Refback 12-29-2009 10:16 AM
GeenStijl : Tendentieus, ongefundeerd en nodeloos kwetsend This thread Refback 12-29-2009 10:15 AM
La Cacharrería: un blog de tecnología diferente This thread Refback 12-29-2009 10:04 AM
Aerodynamic long tail improves fuel efficiency 15 percent This thread Refback 12-29-2009 03:24 AM
Autopia This thread Refback 12-29-2009 12:37 AM
Aerocivic - Honda Civic modifications for maximum gas mileage - aerocivic.com This thread Refback 12-28-2009 06:55 PM
DIY ‘Boat Tail’ Gives Little Car Big Fuel Economy | Autopia | Wired.com This thread Refback 12-28-2009 01:22 PM
Geo Metro boat tail prototype - 15% MPG improvement @ 90 kph / 56 mph - Madshrimps Forum Madness This thread Refback 12-28-2009 07:16 AM
R4 DS Cards, R4 DS and Wii Modchip News And Reviews This thread Refback 12-27-2009 03:21 PM
Mike Szczys - Hack a Day This thread Refback 12-26-2009 05:51 PM
transportation hacks - Hack a Day This thread Refback 12-26-2009 07:35 AM
mpg - Hack a Day This thread Refback 12-26-2009 07:05 AM
Friends This thread Refback 12-26-2009 06:57 AM
Hack: Aerodynamic tail makes Geo Metro even cooler -> ASTALAVISTA.com - the hacking & security community This thread Refback 12-26-2009 03:36 AM
the other end of the spectrum... This thread Refback 12-25-2009 10:44 PM
YouTube - Raw video for: "Testing aerodynamic boat tail +15% MPG" This thread Refback 12-25-2009 09:51 PM
YouTube - Testing an aerodynamic boat tail - 15% better MPG - Geo Metro This thread Refback 12-25-2009 06:07 PM
You put WHAT on your car? Stupid shit we've seen people put on their cars - The Something Awful Forums This thread Refback 12-25-2009 06:03 PM
Hack a Day This thread Refback 12-25-2009 04:24 PM
Geo Metro Mpg - Kosmix : Reference, Videos, Images, News, Shopping and more... This thread Refback 12-24-2009 06:07 AM
Project: removable Geo Metro boat tail - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com This thread Refback 10-21-2009 02:17 AM

Similar Threads
Thread Thread Starter Forum Replies Last Post
Project: Rebuilding an '01 Honda Insight as a nonhybrid Fabio Hybrids 131 01-03-2010 06:13 PM
How to get instant fuel consumption from Megasquirt TELVM Instrumentation 10 10-19-2009 06:28 PM




Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2010, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO 3.3.2
All content copyright EcoModder.com