Motorcycle aerodyamics

[shiphteey]

Excellent info guys  

Total package seems to make the most sense as , given unlimted time to test/tune and RH implied.  Personally I'm in a situation where my OEM ones are cracked so I look at it as a win/win situation.  Smoother aeros, less mass from fairing and removal of heavy headlights, etc.  The price is cheaper than OEM too as 1212 has mentioned.

Technically Landracing is right, the only real way to find out is REAL WORLD.  But given the fact that I'll never be able to duplicate any run 100% it throws some bit of variability into the occaision.  A tailwind, mimimal clutch slip, more wheelspin, 50 psi less nitrous...anything can make a small difference that may make it hard to truely tell....factor in temp changes and ... at least for me @ this stage in the game, it would be hard to come to a "sound" conclusion.  So theory will have to do (smoother aeros up front and less mass.

FiremanJim:  I'm about 1-2" lowered now...may look into going a little lower as something seemingly minor is reported to make a real big difference in the 200+ realm when you're fighting hard.

Stayt: Given the fact that I'm 5'6 and about 125 lbs no gear    I hadn't thought about lowring the seat or removing the tank.  Now that I am, tank removal would be first simply because its just a matter of removing something.  A lower seat would help.  I need to get measured and see if any lil bit of my helmet still is exposed above the stock windscreen.  I want to still use an OEM windscreen because they are already low and sturdy.  If I can cleanly get behind it, I'd be better off than the bubble types due to being lower and seemingly smoother air flow.  Those bubble ones seem more turbulent...but this is just by going w/a "feeling"...nothing proven yet.  If a supercheap seat comes my way I'll consider it  

Pork:  Based on what you're implying and what my instincts are saying, I'm going for a smoother aftermarket tail piece and a smoother front end.  The OEM side body fairings can't have as significant of an effect so they'll stay.  Doesn't seem to be as "cost effective" in this case.  Per others, I have heard leaving the wings on the fairings is smarter for downforce/stability issues.  One variable that I'll leave constant for now.

A.

[shiphteey]

Just stumbled upon this....

http://www.rynofender.com/

Thoughts?  Real world TOP END experiences?  Seemed to help for the 250 2 strokes and 600s.  Incidentally I have an F2 and used to own an 89 FZR 600 ....

Maybe this isn't as much of an issue w/bike that is really lowered so there is minimal gap between the bottom of the ram air and the top of the OEM fairing....?

A.

[hawkwind]

I tried something similar a couple of years ago ,did it do anything ? due to other problems I did'nt have a chance of any serious testing ,I will be trying it again next march

[JackD]

A very successful race team that was contracted to an OEM used a hill.
They would accurately time the the bike as it coasted down a hill.
 Their speeds were under 50 mph but the repeated test with the same conditions
 provided streamlining information that nothing else would.
 The rider even learned to make himself small with no changes to the bike.
 They changed everything on the bike during various tests.
 They always started from a dead stop at the same place and while the conditions might vary
from the start of the session, and day to day, they were able to chart improvements to the package.
 Aero starts as soon as the bike moves through the air and until you go supersonic not much changes.

[hawkwind]

Thanks Jack  
sorry for the large pic blokes

[PorkPie]

I'm going for a smoother aftermarket tail piece and a smoother front end.

Shiphteey,

this will be a clean modification - with the front end -  as I wrote - the rear of the front wheel fender is open like Jim's bike, it's a much better solution than a fender which is closed behind the wheel - especially by high speed.
The side body fairings are no question, they are fine.

To this Rhino horn on the front fender - I saw Hawkwind's picture before and showed that to some friends from the windtunnel - one told me also that someone sales so stuff - I didn't knew who was the company - but all this windtunnel guy's got the same opinion - "psycho trick" - the negative effect will be more than the positive effect and also the positive effect will be only at low speed - less than 120 mph - by higher speed the airflow will be different.
One comment - will help by cross wind - this is totally wrong - especially when you like to go fast straight - the picture shows road course bikes - when did this guys got cross wind

- I like to see this guy between the third and fifth mile marker - once I done a picture from Jon Wennerberg in the fifth mile - going around 170 in a 10 degrees angle - still riding straight - this is what I mean with cross wind......

At last - doing aerodynamic modification - means always to do it step by step - a radical change could create a difficult handling - and you don't know what cause this effect - the step by step solution give you a better and safer feedback - and you know if it works or not.

[stayt`ie]

one of the problems with the zx12`s is the position of the airbox, (it is indridical to the frame and directly above the motor), it restricts you getting ya chest area nice and low,  to compensate you have to get ya bum up high to help flatten your back out ...

[shiphteey]

But I'm 5'6, 125 lbs  

[JackD]

One of the toughest jobs around LSR bikes is to keep rational limits on the streamlining
 and convince them it is safety related.
 Things that might work in another application won't work going fast on the Salt.
 As soon as you go by the notch in the mountain the wind can start, stop,or change directions 180 deg.
Break traction with a wrong bike and it can be a real learning experience.
All of this without asking you.
Get caught in a tire rut and have the wind change and you might find yourself stopping
in a different place than your bike.
As scary as bikes seem to be , they have a very good safety record for reasons
 that are not always well understood.
 "Theoretical streamlining will produce theoretical results."

[joea]

porkpie, ya might want to look abit closer at
back of my (joe's) tail section........it is open not closed off.......

Joe

[stayt`ie]

hay ship, i`m 5'6" at 150lbs fully suited

[JackD]

hay ship, i`m 5'6" at 150lbs fully suited

Ya but I started out at 8lbs 12 oz. and grew for a long time.
Actually you should look at some of the girls.
 With a genetic lower GG and small frontal area to choose from, some of them are really clean through the air.
They often come in smaller overall sizes and can sure ride.
Ya gotta ask yourself are you "Roostering" or do you want to make a bike go faster ?

[shiphteey]

This is about the only place where my size is an advantage...eff it I'm running w/it  

[aswracing]

To Jack's point ... World Finals 2003, Susan on the bike, all 5'2" and 95lbs of her. She could go 161, but was into the limiter which should not have come in until 175 or so (lots of wheelspin). Same meet, same bike, with 5'11" 175lbs me on it, I could do about 150, no wheelspin.

We came back in '04 with a little longer swingarm that had 50lbs on it. Timbo (5'2" 130lbs) went 167.

Probably a bit more if I made a new tank that let the rider get his/her head down.



Here's a shot of Timbo on the other bike. He's a little guy. Big advantage. This is a good body, rounded nose, shrouded wheel, and good reattachment at the rear. The problem with this bike though ...



... is front end lift at speed. The back wants to squat. I've shortened the front and stiffened the back about all I can. Straps on the front make the bike weave.

[JackD]

The smaller the package the better the aero.
 Proper placement of the correct ballast is important at elevated speeds.
 Strapping the front end might work a bit at a dragstrip but less well on the Salt.
What is happening with the strap is that it is working like too much steerng dampning
and the steering can't follow a happy spot as the surface and wind conditions change.
 It tries but is always behind the curve because of the restriction.