Motorcycle aerodynamics, a slippery and windy, slope?

[NeilBlanchard]

A lot of aero car designs have fin(s) in the rear for stability. The Tatra and the Panhard are the best examples.

[Frank Lee]

Center of pressure ahead of center of gravity = instability. No surprise there.

[janvos39]

My experience with driving in gusty sidewind condition is that when I start leaning forward on the seat the handling gets much better.
I made my doors on the scooter dismountable in case of heavy sidewinds, but I never used that option. In a way you get used to some more bike movement with a fairing. Possible in my case the enlarged front wheel fairing is giving negative effects too. I am preparing a fixed front so maybe when that is ready I can find that out.

[PeterS]

Hello all ,I've just joined the forum and am extremely happy to have found this thread !

My current ride a BMW R80 and it is unfortunately uneconomical ,which is a pity because it is otherwise an excellent bike .I don't think trying to make it economical is practical so have decided on another course .

Some people have been converting Indian Enfields to diesel usually using 10 hp Chinese aircooled engines .These bikes are slow , with a top speed of around 50mph unfaired but get remarkable fuel consumption figures ,1.5 to 2.2 litres per 100 km being normal .(156 to 107mpg US ).

However back in the 50s at the time of dustbin fairing in racing the Enfield factory decided to build a moderate fairing for roadbike users .The result was the Dreamliner .



I have other photos should anyone be interested .

It weighed 45 pound , added approximately 8mph to the bike's top speed ( which incidentally was a 13hp 350cc model )and reduced fuel consumption by 25% .

This fairing looks as if it would be a good basis for development .
I've derived it's drag coefficient at .85 which is a great improvement on the standard bike's 1.2 .
With a diesel engine and it's possible 40% efficiency versus 25% for petrol,some quite good fuel consumptions are theoretically possible .

1.44 litres per 100 km or 163 mpg at 50 mph .
.95 l /100km or 247mpg US at 40mph .
Maybe !

Can anyone suggest improvements to the fairing ?

[PeterS]

I'm now going to try to get up 5 posts so I can put up a photo ...please forgive my impatience .

[PeterS]

Three .

[PeterS]

Four.

[PeterS]

[redyaris]

Originally Posted by PeterS

Hello all ,I've just joined the forum and am extremely happy to have found this thread !

My current ride a BMW R80 and it is unfortunately uneconomical ,which is a pity because it is otherwise an excellent bike .I don't think trying to make it economical is practical so have decided on another course .

Some people have been converting Indian Enfields to diesel usually using 10 hp Chinese aircooled engines .These bikes are slow , with a top speed of around 50mph unfaired but get remarkable fuel consumption figures ,1.5 to 2.2 litres per 100 km being normal .(156 to 107mpg US ).

However back in the 50s at the time of dustbin fairing in racing the Enfield factory decided to build a moderate fairing for roadbike users .The result was the Dreamliner



I have other photos should anyone be interested .

It weighed 45 pound , added approximately 8mph to the bike's top speed ( which incidentally was a 13hp 350cc model )and reduced fuel consumption by 25% .

This fairing looks as if it would be a good basis for development .
I've derived it's drag coefficient at .85 which is a great improvement on the standard bike's 1.2 .
With a diesel engine and it's possible 40% efficiency versus 25% for petrol,some quite good fuel consumptions are theoretically possible .

1.44 litres per 100 km or 163 mpg at 50 mph .
.95 l /100km or 247mpg US at 40mph .
Maybe !

Can anyone suggest improvements to the fairing ?

Please provide a referance for the Cd of 1.2 for the standard motorcycle?

[Frank Lee]

Originally Posted by PeterS

Neato, but probably still an awful Cd.

Originally Posted by PeterS