General topics » Motorcycle Aerodynamics

I think you will find this article interesting. In particular, I liked this quote:

It may come as a shock to most motorcyclists, particularly those used to reading boastful claims in motorcycle advertising to the contrary, but 99% of motorcycle OEMs don’t give a damn about aerodynamic efficiency. The reason? It’s such a lost fight that it isn’t worth the effort.

http://canadamotoguide.com/2016/05/04/mo...e-aerodynamics/

Hoerner FD Drag - MC&Car Drag - small.jpg - Bild entfernt (keine Rechte)

Going with the classics from Dr. Hoerner, which the article explains in text

BTW - Turbulence and separated flow are two different things in the field of Fluid Dynamics. Turbulence is the random vorticial flow structure within a turbulent boundary layer (i.e. the stuff that makes noise of the airplane hull and thus the reason for the cheapest seats at the tail). A non-separated flow can be highly turbulent and low drag. The separated, eddy flows behind a bluff body are highly turbulent, but as the golf ball example proves...….a rough surface can reduce drag by inducing a turbulent flow which delays flow separation that the laminar flow on a smooth surface. Confusing, no?

Zitat von Richard230 im Beitrag #1

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I think you will find this article interesting. In particular, I liked this quote:

It may come as a shock to most motorcyclists, particularly those used to reading boastful claims in motorcycle advertising to the contrary, but 99% of motorcycle OEMs don’t give a damn about aerodynamic efficiency. The reason? It’s such a lost fight that it isn’t worth the effort.

http://canadamotoguide.com/2016/05/04/mo...e-aerodynamics/

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Nearly as good as a barn door

Zitat von Richard230 im Beitrag #1

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It may come as a shock to most motorcyclists, particularly those used to reading boastful claims in motorcycle advertising to the contrary, but 99% of motorcycle OEMs don’t give a damn about aerodynamic efficiency.

http://canadamotoguide.com/2016/05/04/mo...e-aerodynamics/

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Zitat von Lee im Beitrag #3

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If you have a big rider on a GS with hotdog boxes for panniers it's going to have a poor Drag Coefficient .

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136Hp in a 250-kg vehicle carrying a 100kg rider doing 130mph doesn't impress me. But, my 159-hp, 1750-kg Tacoma carrying 90-kg me and towing my RS on a Uhaul trailer at 80-mph, does...…….

Until all riders are the same size and wearing identical gear, motorcycle aerodynamics will always be a compromise.

Aerodynamic efficiency appears to be an area of massive opportunity for bike designers - why the lack of progress?

Is it because they are seen as "Leisure/lifestyle" vehicles and therefore not worthy of serious development? Or is it less costly to continually bump up the BHP?

I guess this is the reason why my 2.0l car has a higher top speed and is more economical than my RS, despite weighing 5x more but having little more than an extra 60bhp.

I do not know much about aerodynamics but is the reason essentially that if you really did make a PTW truly efficient aerodynamically, it would be so unstable in the infinitely varying (and therefore unpredictable) winds as to be unrideable? I am thinking of the wonderful, all-enclosing, dustbin fairings used in the immediate post-war period of grand prix racing, that were eventually banned because of their dangerous instability and inability to corner predictably. If memory serves, they were so efficient that they also introduced major problems with braking because there was so little wind resistance to slow them down and the drum brakes of the time were a bit basic. Moto Guzzi were also able to win races with a single cylinder 500cc engined racer with very little power but amazingly low wind resistance a a result of both the fairing and the low frontal area of the forward canted single. BUT, how about this:

https://www.classicdriver.com/en/article...guzzi-v8-homage

Oh, I think I may be in love!

As a car has four wheels, it is inherently much more stable, especially in cross-winds and therefore aerodynamic designs can be pushed much further without the same concerns as to instability. I think that the only way a motorcycle could be made truly aerodynamic may be to enclose it fully but then you would immediately hit the problems of instability.

This might all be simplistic tosh of course!

I wpould really love someone to make a modern version of the 70's Quasar

Zitat von Fugly im Beitrag #11

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I wpould really love someone to make a modern version of the 70's Quasar

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Zitat von Mr. 36654 im Beitrag #4

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Nearly as good as a barn door

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Zitat von Clifton im Beitrag #13

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Zitat von Mr. 36654 im Beitrag #4

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Nearly as good as a barn door

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About the same..... or even worse.

Years back talking with an engineer at Buell he described just how awful the aerodynamics on most motorcycles are. If you took a frontal pic of a motorcycle (2 dimensional) in actual size and cut around the outer edge like one of those cardboard store displays, then transferred that to a flat piece of plywood and pushed it through the air, it would be more aerodynamic than the motorcycle it was based on due to all the vortices.

I can say though my R1200RS seems to slip through the air a little better than my previous R1200GSA and it gets better MPG too.

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It's not like pushing a rounded lump compared to a plate through the air because the "rounded lump" is actually a shape that's made from a whole conglomerate of bowls, flats, cubes, angles, etc. which each make their own vortices which contributes to more turbulence. A car's shape is more like your rounded lump analogy.