Motorcycle aerodyamics

[PorkPie]

"Theoretical streamlining will produce theoretical results."

Good point.

Understanding aerodynamic - means - you could read the airflow.

This is the reason why I wrote step by step.

Joe - could be that I forgot how your rear end (I mean this from the bike ) looks - but you know what I mean when I point on John Noonan and Jon Wennerberg - they both use this aero kit.

I like the front fender from the #1987  bike, clean front covered, right open on the rear so that the air can escape - also the air from the turning wheel.

See ya

[JackD]

A front fender will pump air in the area between the tire and the inside surface.
 Many try to limit that action by closely fitting the fender to the shape of the tire.
 The problem is the tire changes shape at speed.
The solution has been to fit an air dam inside the fender that works like a scraper
you might have to take oil off a crankshaft.
It is fitted exactly to the shape of the tire at rest.
The material is a polyethylene that is thick enough to support it's self but soft enough
 to wear away to the contour of the tire at speed without damage to the tire.

[k.h.]

John Britten's AERO-D series of bikes, circa 1985, with the "parrot beak" fairing coming forward over the front wheel did pretty well in the BEARS speed trials.  Seems there was a dark metalic blue bike on the salt a year or two back with a similar front fairing configuration.  Did it go fast?  

http://www.britten.co.nz/history/aerobike.html#part3r

[PorkPie]

A front fender will pump air in the area between the tire and the inside surface.

Jack, this is what I meant with "also the air from the turning wheel".

It's a lot of air which the spokes pump inside the fender.

See ya

[JackD]

A correct amount of turbulent air is required around the front wheel to allow
it to work on the bike without the effects of the wind.
 Too much smooth air flow and it will work like a rudder on the front of a boat or plane.
You don't see full disk wheels on the front of an open bicycle for a reason.
It is just like canards on a bike.
 Theoretically they really push a bike down to load the suspension.
In any cross wind, they push one side more than the other and "Down" quickly takes on a whole new meaning.
 

[John Noonan]

"Theoretical streamlining will produce theoretical results."

Good point.

Understanding aerodynamic - means - you could read the airflow.

This is the reason why I wrote step by step.

Joe - could be that I forgot how your rear end (I mean this from the bike ) looks - but you know what I mean when I point on John Noonan and Jon Wennerberg - they both use this aero kit.

 like the front fender from the #1987  bike, clean front covered, right open on the rear so that the air can escape - also the air from the turning wheel.

See ya

Here is the bike at the USFRA meet in 04,


after that I took the custom tail section off and the bike was run with the stock OEM tail section to a speed of 253mph like this.





And here is the bike now as it was in Australia, same as it was when it ran 259+ at the Bub's meet last year.  



Bike is for sale...

[JackD]

You can bet the OEM people spend a lot of time and money to get the best aero package for efficiency (speed) and ride-ability.
Their work also reflects an effort for the bike to handle well in lots of conditions that are much like you might experience over the distance of a run at the Salt.

[PorkPie]

John,

thanks that you took the picture on the forum.

The picture shows what tried to explain.

Due to this that I was the last time for the WoS 2004 at the Salt, I didn't knew that you chanced your fairing for the WF.

So you moved over to the better aero solution, therefore I have a question - you improved your speed with the change, did you felt also a different in the handling, like the bike was pushing better or it runs better straight. Would be interest to hear the expierence from you, after you rode both versions. Please, let us know. Thanks

and we see us at the salt

[JackD]

While the white body would seem to move the CG forward, the CP back,
 and smooth the exit air in theory it actually produced real problems.
 Not so much as it was wrong but the conditions were not right and are constantly
 changing beyond your control.
The variable cross winds are not going in the
direction you want to go and will prevail over you without asking.
Imagine how you might carry a full 4X8 sheet of plywood.
 Now run with it.
 Now introduce a slippery surface and then a variable cross wind.
Move to the front and then to the back.
Try it really high and really low.
Cut down on the size of the plywood and everything gets easier.
Plywood always works the same, it is the bike that
 has not been perfected yet.