Motorcycle aerodynamics, a slippery and windy, slope?

[dcb]

Also take a look at another current design:
214 mpg with DIY aerodynamic fairings on a Honda 125cc motorbike | Hypermiling, Fuel Economy, and EcoModding News - EcoModder.com

claims: “A 40mph (65 km/h) side wind is no problem,”

no front overhang, but also not a tapered long high tail either.

[euromodder]

Have a look at the fairings, streamliners and related info on Craig Vetter, designer and inventor of the Windjammer fairing,Triumph Hurricane Motorcycle and fuel economy motorcycles .

And of course there's Allert Jacobs streamlined 125cc on the ecomodder.com homepage.


You've got some big shoes to fill when you want to walk with giants .
Craig's fairings are legendary, and Allert is world famous in the world of velomobiles and recumbent cycles

[Kincurd]

Originally Posted by dcb

Also take a look at another current design:
214 mpg with DIY aerodynamic fairings on a Honda 125cc motorbike | Hypermiling, Fuel Economy, and EcoModding News - EcoModder.com

claims: “A 40mph (65 km/h) side wind is no problem,”

no front overhang, but also not a tapered long high tail either.

Yes, I saw that. It's a beautiful design. One way you could improve on it, is by sitting where your feet normally are, and then you'd be able to cut down the side surface area and lower your center of gravity.

[dcb]

I'm really not sure if lower CG helps or not here. Certainly lower center of pressure helps, and having the center of pressure below the center of gravity means the side winds will have to work harder to tilt the bike.

Sort of like the c-clamp on a yardstick trick.

[Kincurd]

Yeah, on second look, he's already sitting very low. He'd have to extend the frame and sit in front of the engine to get any lower; which might defeat the purpose, since it'd extend the surface area longwise, for just a few inches off the top.

[dcb]

He also mentions 80lbs of aero mods helping with crosswind stability.

Another thing to note is that he has rounded trailing edges. Normally we like a nice sharp transition into the void for reducing drag, but I have heard folks comment on that having a negative effect on crosswind response in cars (increases the effective tail size with a wall of wind?)

[Varn]

My varna has been ridden in high winds during competition at 50 mph for an hour. The wind definitely makes a difference in handling, our rider didn't slow down when crossing dust devil cyclonic storms in his path. A trike might be a lot easier however. Graft on an ATV front end onto a motorcycle and fair it in. The CanAm I think really missed the boat when it comes to efficiency with their trike.

[Kincurd]

Yeah, the trike would be a simple design fix, but I really like the two-wheel set-up. I still want a bike and the handling that goes with it.

It's been slow at work, and I've just been sketching away at various ideas. It's really kind of silly, but I've got so much time to think about this before I have a bike. In theory I could have a lot of stuff built before I even get the bike.

[visionary]

Surely there are some forum contributors who can give us honest feedback about how the Ecomobile rides in sidewinds.
Since this is the only real fully enclosed motorcycle in widespread use it must be our best point of reference.

[Kincurd]

One thing is, on Allert Jacobs' blog, he mentions some crosswind trouble when he had only the front dolphin-esque fairing. He was able to eliminate the instability when he went all out, covering the whole bike.


"The front wheel fairing has to go to. I was quite confident that it would work and not affect the steering to much.

It turned out to be very scary to ride even with as little as 3 beaufort (about 10mph) side wind I did not dare to go over 35mph. It is a pity I made a mould and all without ever testing with a cardboard model."

Taken from:
http://www.velomobiel.nl/allert/Recu...0motorbike.htm