98+ Kat - Very Favorable Aerodynamics?

[The CyberPoet]

As many of you know, the most aerodynamic motorcycles ever built all share a common design -- basically the same design as a rain-drop upscaled (front end as the broadest cross-section, everything tapering back from there to a tight-tip closure). Back in the day, bikes that ran this on the track kicked the butts of bikes not using this kind of fairing shape, and did it so effectively that all the racing bodies wrote up regulations to prevent the extreme shapes from being used... Which is why modern race-reps, although pretty on the eyes, always leave some of the engine exposed at the sides and have sharp angles (the enemy of aerodynamics in general).

The typical motorcycle has about the same aerodynamic drag co-efficient as a 1950's milk truck or an UPS delivery truck, with typical Cd values ranging from .42 to .58 (a '90 Ford Ranger XLT has a .45 and a 92 Honda Civic SI clocks in at .31).

This got me to thinking about what motorcycles actually have favorable fairing designs, and the only two that popped to mind immediately are the Busa and the Kat, both of which used the same basic computer-particle modeling data to maximize their shapes (and which caused a lot of people to think of them as "ugly" compared to the sleek but non-aerodynamically efficient GSXR/R6/R1/etc).

Thoughts, comments? Did I maybe miss some other bikes that share the same basic tear-drop shape perhaps?

Cheers,
=-= The CyberPoet

[SweetLou]

I would like to add....

The bike is very areodynamic, but with my 6'5" frame, and my phat arse on it... it is no longer areodynamic

[Kat-A-Tonic]

I heard comments from "bulbous" and "ugly" to "cool" and "nice" looking about the Kat. The bike cuts through the air quite nicely and I would think it's shape would help in performance.

As for other bikes sharing the design, I don't recall anything off-hand.

[jason05]

i think the nose of the bike needs a little work. the (windscreen) angle is too steep.... though it makes for nice upright riding. when i make a 100mph+ pass near friends on the side of the road parked... they say it sounds like im pushing a bunch of air... but this isnt heard when a R bike goes by. just a thought.

[Micdalen]

I have to agree cyber. Although not blessed with the modern flowing bulbous lines, the kat is very aerodynamic. The design is very basic in thought and well conceived.

The flowback from front to back is gradual, not a sharp drop off that creates turbulence, but allows the air to flow out.

If ya dont think it is areodynamic do a wen search for the air launched cruise missile. Although it looks odd, in comparison is is very similiar in design to the kat. Take a look

http://www.fas.org/man/dod-101/sys/smart/agm-86c.htm

not good back shots but it is tapered in design.

[WildKat]

The full fairing kats are very aerodymanic IMO as well. The entire design flows very well together and very streamlined.

Most of your supersport bikes are very choppy in design, they still look sweet, but they dont always "flow" in design the way the kat does.

[tzortn]

You can't just use a bikes coefficient of drag as a metric for aerodynamic efficiency. A formula one car for example has the drag coefficient of a bus, but it also produces a tremendous amount of balanced downforce while feeding air to the areas that need it for cooling. I am sure that a lot of wind tunnel and CFD work goes into designing a SS bike such as the YZF-R1. To call any of these SS bikes non-aerodynamically efficient is a mistake.

[mx916]

It seems the front aerodynamics are fine. I guess the rear is nice and aerodynamic but to me it still looks like an excited dog. (Figure it out)

[skasner]

lol... red rocket. that's why i want to get the clear tail put on mine.

[trinc]

poor aerodynamics can be overcome with HP and the modern SS bikes have no shortage of that.

the talk of the town is more about which bike has more HP - not which bike has the best 1/4 time. sales will always have a percentage of sheep mentality & a 'cool' or looks factor.

but i disagree with the design of the teardrop, when i look at the utah salt races - slim / narrow is what is being built ( kind of like the v-twins )


tim

[smileyman]

Aero package

Kawasaki has spent a great deal of time on the ZX14, ZX10R, and ZX6R perfecting the aero in a wind tunnel. They highly praised their results on all 3 bikes. However, as with some MotoGP designs, better front to back aero has some disadvantages in cross or side wind situations. Yamaha and Honda have done lots of bike aero w/ rider research to help riders better understand how posture and body positioning has a role in aero efficiency.

IMHO the ZX10 and 14 are fairly ugly compared to the R1 and CBR, but then so is the 'Busa. I like the Katana shape though. However, this is mainly a visually pleasing vs aerodynamic efficiency argument though. Not all visually sleek vehicles have good aero qualities.

My primary concern though is wind on the rider not shaving the last .001 second from a time sheet somewhere. As the bikes get more hp it seems a shame to leave your arse flopping out there in the wind while the bike cuts a fine hole into the atmosphere.

[NitrousGuy]

I get less air buffeting on my kat6 than on my bandit12 (shrug)

[gsxr6racer]

I don't see how you can say that bikes are not aerodynamically challenged. There frontal area is crazy for there size. And if you have a drag coefficient of .42 to .50 after a certain speed you are phucked... nothing you can do about it. The new GSX-R 750 is apparently very aerodynamic - and it's tiny compared to the last version! To be aerodynamic, bikes need to get smaller.

I don't think Kat seems very aerodynamic, like Jason said, windscreen is too tall and steep and the area is too flat, not as flat as the pre 98's, but still too flat.

[The CyberPoet]

but i disagree with the design of the teardrop, when i look at the utah salt races - slim / narrow is what is being built ( kind of like the v-twins )

Actually, I picked the raindrop because it should be the most optimized shape for transition through air (since it's a liquid, it reforms itself in direct response to the pressure gradients, air resistance and speed). It's a theme you see in a lot of aerodynamically advantaged vehicles, from 747's to the fastest of the bonneville racers, although the rain-drop shape is normally elongated (because the vehicles moves faster than falling rain does at terminal velocity)


Even the 50cc world speed record holder modified the fairings the same general way (from a fairing that is much narrower & smaller from the factory):


Cheers,
=-= The CyberPoet

[smileyman]

Either way we have come along way from the Dust - bin days. It would be interesting as well to see a wind tunnell comparo of say a 1989 ZX10 and a 2006 Zx10. Likewise a 93' GSXR1100 vs. 06' GSXR1000. We all know they have improved, but by how much?