An Aerodynamic Device or Fender

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In summary, there is a debate over the purpose of a plastic component mounted below the number plate on certain motorcycles. While some users claim it is to keep dirt out of the hole in the bottom of the neck of the triple trees, others believe it re-directs air and reduces drag. However, it has been concluded that without a proper CFD analysis, it is impossible to determine if this component offers any aerodynamic advantage. Some also suggest it may be for protection of the fork suspension or to redirect airflow to cool the engine. Ultimately, it is unclear what the true purpose of this component is.
  • #1
AMPOWN
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Please advise if the plastic white component mounted below the number plate on these motorcycles is or is not an Aerodynamic device that could afford an advantage at 100+ MPH over an identical motorcycle without this device? Users claim it is to keep dirt out of the hole in the bottom of the neck of the triple trees that hold the forks. I submit, if that be the case, why not just simply use a piece of lightweight tape instead of this heavier part?

The components in question are below the number plates on the #4 and #59 Motorcycles. I submit they re-direct air downward, thus avoiding the fins of the cylinder on the engine, and force it to run under the chassis, where it creates far less drag than running through the fins on the cylinder.

http://amaproracing.com/images/content/story/Springfield_featured.jpg

American Motorcyclists Association AMA in Daytona Florida Tech Directors state that they feel this device affords zero aerodynamic advantage. And they also contend that it is not a fender to keep dirt off the lower Triple Trees. We are trying to determine just what the hell this thing is then?

Thanks in advance for your input.
 
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  • #2
http://i481.photobucket.com/albums/rr177/mikebike11y/Picture1-16.png

Side view of the curve of the component in question.
 
  • #3
My opinion is that this feature will not give any discernible aerodynamic advantage on those bikes (with wide bars, tyres, no fairings, race numbers etc), but you'd need at least a CFD study (and possibly a wind tunnel test) to tell for sure.
 
  • #4
I looks more like it would redirect airflow over the engine to cool it down better.
 
  • #5
The finish in these races after 25 laps on a mile dirt oval is .001 - .045 seconds at the finish line for the top five bikes. Last race the finish difference was .000 measured using AMB-IT Transponders. Photograph was used to determine the winner.

With that said, if this component would reduce drag at any percentage, it could make the difference in the outcome of one of these contests.

Looking at this CFD Study, one notes that a very minor change in shape of the SUV body, reduces drag.

http://csus-dspace.calstate.edu/xmlui/bitstream/handle/10211.9/123/Thesis - Final.pdf?sequence=1
 
  • #6
You can't take a study done on an SUV and apply it to a dirt bike. They are totally different animals. Honestly, like brewnog said, based on the information you have provided I can't think of any possible aerodynamic advantage to the part in question.
 
  • #7
More no the machines these are mounted on.
While they race on hard packed clay surfaces, these machines exceed 145mph on the long straights. They are not Dirt Bikes like Moto Cross. Over 100hp weighing 300lbs, they race on oval tracks, many used for horse racing. Drafting to the finish with six or more in line is common for the 25 laps on the Mile tracks. Typical finish has four or five crossing the finish line less than .003 seconds apart at over 140mph.
 
  • #8
And despite all of that, there is still no discernible aerodynamic advantage conferred by these devices. I am sorry, but unless you hire someone to do a full CFD analysis, the best we can all say is that it appears to not offer an advantage.
 
  • #9
It looks to me like protection for the fork suspension. You don't want rocks and other debris denting or damaging your shock/suspension rods.

Its a rounded cover for a thinner, rounded rod, I doubt it has any positive aerodynamic effects.
 
  • #10
Just curious, but what is your personal concern? Are you a rival competitor?
 
  • #11
Allenman said:
I looks more like it would redirect airflow over the engine to cool it down better.

That and keep spray from the tires in wet weather out of the rider's face.
 

FAQ: An Aerodynamic Device or Fender

1.

What is an aerodynamic device or fender?

An aerodynamic device or fender is a structure or attachment on a vehicle that is designed to improve its aerodynamics, which in turn can increase fuel efficiency and reduce wind resistance. Fenders are typically found on the front and rear of cars, while aerodynamic devices can include spoilers, air dams, and side skirts.

2.

How do aerodynamic devices or fenders work?

Aerodynamic devices and fenders work by redirecting the airflow around a vehicle, reducing drag and turbulence. Fenders, in particular, help to channel air away from the wheels and tires, which can cause significant drag. Spoilers and air dams create a downward force, improving the car's stability at high speeds. Side skirts also help to smooth the airflow along the sides of the vehicle.

3.

What are the benefits of using an aerodynamic device or fender?

The main benefit of using an aerodynamic device or fender is improved fuel efficiency. By reducing drag and turbulence, the vehicle can move through the air with less resistance, resulting in better gas mileage. Additionally, aerodynamic devices can improve the handling and stability of a vehicle at high speeds.

4.

Do all cars need aerodynamic devices or fenders?

No, not all cars need aerodynamic devices or fenders. The design of the car and its intended use can determine whether these attachments are necessary. For example, sports cars and high-performance vehicles often have built-in aerodynamic features, while more practical cars may not require them.

5.

Are there any downsides to using an aerodynamic device or fender?

One potential downside of using an aerodynamic device or fender is the added weight and cost. These attachments can be heavy and may require additional materials and labor to install, which can increase the overall cost of the vehicle. Additionally, some aerodynamic devices may also impact the aesthetics of the car, which may be a concern for some drivers.

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