Go Back   EcoModder Forum > EcoModding > Motorcycles / Scooters
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 12-19-2016, 12:42 PM   #31 (permalink)
Master EcoModder
 
gumby79's Avatar
 
Join Date: Dec 2014
Location: Butte, Montana
Posts: 725

little jona - '91 Dodge D 250 first gen cummins LE
Team Streamliner
90 day: 23.4 mpg (US)

Little Jona airo modded - '91 Dodge RAM 3/4 TON D 250 2×4 AUTO
Pickups
Team Cummins
90 day: 18.5 mpg (US)

The Salted Hound Jenny. - '87 Dodge Ram 50/D-50 5sp 4X4
90 day: 20.24 mpg (US)

Jona Allison aero - '91 Dodge Ram D-250 Le
90 day: 20.76 mpg (US)
Thanks: 208
Thanked 423 Times in 276 Posts
Rules interpretation

Quote:
5.2.12 No streamlining may be attached to the rider.
..... this makes my prvious tail/butt fairing useable, unless it is attached to the tail of the bike.
Quote:
5.2.12.A. All fairings must be made of plastic, fiberglass or carbon fiber.
.... Theas are the materials you can use for your mods. Except parts associated with drake cooling and wind deflectors.

Quote:
5.2.11 Fairings must be mounted in at least three locations. The front wheel
must be clearly visible from both sides except for the portion covered by the fender. The rider must be visible from the side and above, while in a normal riding position, and transparent material may not be used to allow for such visibility.
....I read this to mean the entire front wheel/tire can be covered by a 1pice finnder
Quote:
5.2.4.C. Aftermarket brake cooling ducts or wind deflectors may be made of metal providing the design does not pose a safety risk to any competitor.
Final approval of unit rests with the Tech Inspector. (each and evry race)
A 1 pice finnder would combine both 5.2.11 and 5.2.4.c

Quote:
5.2.10 Rear fender or seat must extend to the rear of a line drawn vertically at
the rear axle.
They state a minimum... no maximum. Added length is a compromise between reduced aerodynamic drag and increased Rolling Resistance coefficients. Use Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com to figure out how far you can go and see a benefit.
Gumby Stay Flexible.

__________________
1st gen cummins 91.5 dodge d250 ,HX35W/12/6 QSV
ehxsost manafulld wrap, Aero Tonto
best tank: distance 649gps mi 24.04 mpg 27.011usg
Best mpg : 31.32mpg 100mi 3.193 USG 5/2/20


Former
'83 GMC S-15 Jimmy 2door 2wd O/D auto 3.73R&P
'79 Chevy K20 4X4 350ci 400hp msd custom th400 /np205. 7.5-new 14mpg modded befor modding was a thing
87' Hyundai Excel
83 ranger w/87 2.9 L FI2wd auto 18mpg on the floor
04 Mitsubishi Gallant 2.4L auto 26mpg
06 Subaru Forrester XT(WRX PACKAGE) MT AWD Turbocharged 18 plying dirty best of 26mpg@70mph
95Chevy Blazer 4x4 auto 14-18mpg
04 Chevy Blazer 4x4 auto 16-22mpg


  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 12-19-2016, 12:58 PM   #32 (permalink)
Permanent Lurker
 
seifrob's Avatar
 
Join Date: May 2011
Location: Czechoslovakia (sort of), Europe
Posts: 333

Dáčenka - '10 Dacia / Renault Logan MCV 1.5 dCi (X90 k9k)
90 day: 47.08 mpg (US)
Thanks: 125
Thanked 182 Times in 81 Posts
Quote:
Originally Posted by jakehammer2000 View Post
Is this one available as a transparent overlay? I am only finding the side view
In tool "aerodynamic template overlay" select "Template #2" in point 4 of upper table. You should see it.
  Reply With Quote
Old 12-19-2016, 04:16 PM   #33 (permalink)
EcoModding Apprentice
 
Join Date: Dec 2011
Location: San Francisco, CA USA
Posts: 142
Thanks: 6
Thanked 53 Times in 31 Posts
Harley XR750 long-track fairing with custom large/shallow taper seat:







The HD and Norton JPN fairing are the main "classic" RR fairings that I know of that were wind tunnel tested instead of styled. The HD was done by the Wixom brothers in the CalTech tunnel and I think the Norton at MIRA.



A 13" wide seat like that on the red bike (shown is a 15" seat) added 500 RPM in top gear to a pretty stock CB125 Honda engined bike and was good with tuft testing at freeway speeds. That bike had about 7-8 hp. Most rider's butts are 15+" wide and the seat should match the rider and fill in behind the legs to give a smoother outer surface.

Here's a photo of the last version of my Laverda F750 racer with HD fairing and big seat (not the same as the "big butt" HD seat):



The back of the bike is more important than the front, and remember that the bodywork is there to streamline the rider NOT the bike. Unless you've got a CBX or a Boss Hoss the rider is the wide part of the combo.

Most rule books I've seen exempt the hands and forearms from the "rider must be visible from the side/top" rule.

If you look in this folder on my website

Index of /graphics/aero

you'll find a scan of an article (Free Speed) comparing 1970s RR fairings, including the Norton and HD.

Try to find a copy (used only available at this time) of John Bradley's "The Racing Motorcycle, Vol 1" as it has a lot of good info on RR streamlining including the wind tunnel runs on the Can Am LSR bike.

The trend in modern bikes seems to be to lower the top of the tank to make the rider's back more horizontal. Of course, that can make it difficult for the rider to see where they are going if they can't tilt their head back far enough.

cheers,
Michael
__________________
http://www.eurospares.com
  Reply With Quote
The Following 6 Users Say Thank You to Michael Moore For This Useful Post:
briantrice (12-21-2016), California98Civic (12-19-2016), Daschicken (01-20-2017), Grant-53 (12-20-2016), gumby79 (12-19-2016), jkv357 (12-20-2016)
Old 12-19-2016, 05:20 PM   #34 (permalink)
Cyborg ECU
 
California98Civic's Avatar
 
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,099

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: 2,310
Thanked 2,034 Times in 1,384 Posts
Those are good Michael Moore!
__________________
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.



  Reply With Quote
Old 12-19-2016, 05:41 PM   #35 (permalink)
EcoModding Lurker
 
Join Date: Jan 2008
Location: Maine/Nova Scotia
Posts: 87
Thanks: 9
Thanked 21 Times in 13 Posts
Typical land speed front fender, supposedly good for 2-3 mph:

  Reply With Quote
Old 12-20-2016, 08:36 AM   #36 (permalink)
Permanent Lurker
 
seifrob's Avatar
 
Join Date: May 2011
Location: Czechoslovakia (sort of), Europe
Posts: 333

Dáčenka - '10 Dacia / Renault Logan MCV 1.5 dCi (X90 k9k)
90 day: 47.08 mpg (US)
Thanks: 125
Thanked 182 Times in 81 Posts
Can you relocate your exhaust above rear wheel to fill the wake?
  Reply With Quote
Old 12-20-2016, 02:54 PM   #37 (permalink)
Master EcoModder
 
Join Date: Feb 2010
Location: Elmira, NY
Posts: 1,729
Thanks: 305
Thanked 333 Times in 278 Posts
Good stuff. Some organizations limit the height of the tail box so you might want to check into that. If your back is horizontal with a slight curve, be sure there is no gap between you and the tail. A top view should look like a teardrop to minimize air flow separation. One trick we use on our pedal bikes is to streamline the spokes on the front wheel and use smooth disk wheel covers on the rear.
  Reply With Quote
Old 12-20-2016, 05:02 PM   #38 (permalink)
EcoModding Lurker
 
Join Date: Jan 2008
Location: Maine/Nova Scotia
Posts: 87
Thanks: 9
Thanked 21 Times in 13 Posts
Something else to consider is whether or not you can get adequate leverage on the bars/clip-ons if you move them inboard. You might have to move the master cylinder inboard of the clamp or something similar, but that mod allows you to get your elbows out of the windstream some more. Also, consider running some duct tape around the top of your boots.
  Reply With Quote
Old 12-20-2016, 05:34 PM   #39 (permalink)
EcoModding Apprentice
 
Join Date: Dec 2011
Location: San Francisco, CA USA
Posts: 142
Thanks: 6
Thanked 53 Times in 31 Posts
On my 216cc Honda vintage racer I made the bars very steep and narrow to encourage me to stay on the tank (the only time they were comfortable) as much as possible.







It ended up with a fairing that was sort of a 7/8 scale version of the HD long track part. A long Seeley aluminum fender never got installed on the bike before I moved on to other projects:

__________________
http://www.eurospares.com
  Reply With Quote
The Following User Says Thank You to Michael Moore For This Useful Post:
Frank (12-20-2016)
Old 01-11-2017, 02:45 PM   #40 (permalink)
EcoModding Lurker
 
Join Date: May 2009
Location: Ithaca, NY
Posts: 6
Thanks: 0
Thanked 5 Times in 3 Posts
LSR example.

I did a bit of research and some fluid dynamic work when I was building my land speed racing moped. It is my belief that you want to do as much as you can to reattach the air behind you to minimize the vacuum. The attached photo isn't the final result but you get the idea. I was not able to get any wind tunnel testing but the bike holds the record for being the fastest 50cc motorcycle to run at the Ohio Mile. It is a 1977 Puch single speed moped so I suspect the aero had to help. The rear section starts out as the width of my butt and tapers as much as possible without the air separating then is chopped flat as per the rules pertaining to how far back the aero may extend.

Attached Thumbnails
Click image for larger version

Name:	Moped.jpg
Views:	80
Size:	81.1 KB
ID:	21147  
  Reply With Quote
The Following User Says Thank You to CoClimber For This Useful Post:
jkv357 (01-11-2017)
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com