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Old 07-09-2015, 08:46 PM   #1 (permalink)
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A straight sided fairing ?

A question for those who know such things. I've been thinking yet again about the ill effects of a tapered fairing... that lovely classic shape which has the unfortunate effect of flicking you around if the wind off a truck or around a building hits unexpectedly.

How about the flat sided fairing, like a pyramid , wider at the front but with the leading edge low tapering up but the maximum width at that point then coming back to a reduced dimension at the extreme back?

This is rather hard to explain but my scanner is dead, a drawing would be a better way of explaining.

This photo of the Dome racing car was the inspiration for the idea. Flat sides ,thus no lift !

No side lift is what I'm after.


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Old 07-10-2015, 01:26 AM   #2 (permalink)
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The vertical fin area gives a surface for the wind to push from the side. To minimize lift and reduce side wind load we use a curved body. The cross section is like an inverted egg with the larger radius at the top.
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Old 07-10-2015, 04:08 AM   #3 (permalink)
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I understand the theory Grant but that egg shaped side generates side lift that can be deadly. The flat side would have the same surface area for the win to push against but would not generate side lift if the wind is off to the side.
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Old 07-10-2015, 05:27 AM   #4 (permalink)
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Side lift? referring to the reason nascar, and land speed record cars use roof rails? adding side skirts might be easier to do, help just as much, and have less chance for unintended effects.

Edit: nevermind, I'm a dumbass stuck in 4wheel mode

Last edited by 2000mc; 07-11-2015 at 01:45 AM..
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Old 07-10-2015, 05:47 AM   #5 (permalink)
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What would the side skirts do mc ?
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Old 07-10-2015, 07:00 AM   #6 (permalink)
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Side force elimination

Hi Peter, I'be followed your previous postings about motorcycle body designs and I get where you are coming from
Unfortunately there is no easy answer to your quest (I've been looking for it myself) because of the complex nature of "side lift".

Lift has two components, Newtonian and Bernoullian, and you are searching for a means of eliminating the side force ONLY using Bernoulli's principle. Even if you were able to do this ( as your question implies) it would still leave the Newtonian component, which as it applies to motorcycles is the greater of the two forces.
A useful explanation can be found here http://youtu.be/zUehWUoiPHQ

Your efforts to reduce sidewind sensitivity should be aimed at reducing the "sail area",and lowering the Centre of Pressure (ie height above ground). This will reduce the turning moment around the tyre contact patches and reduce the lean angle, thus aiding stability.
One of the central problems with traditional motorcycle design (ie those that keep the normal hands first riding position) is that a high centre of gravity also implies a high centre of pressure
Attempts to enclose the upper body area of a motorcyclist will inevitably result in a large "sail area", high above the contact patches, and therefore a large overturning moment.
To make any real progress in this area you will need to consider recumbent riding positions or active aerodynamics.
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Old 07-10-2015, 07:36 AM   #7 (permalink)
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Thank you , a great reply .

It seems to me that flat sides would negate side lift almost entirely, that's the Bernoullian component dealt with or am I missing something ?

As you say the Newtonian component is the problem that remains and feet forward seems the obvious response. I think a Honda CT110 would make an ideal basis for such a bike, for me at least. There is a bloke who posted an excellent thread on his Honda 90 version of feet forward and I've been thinking about it ever since . This basic design should work but if I add a Vetter style rear section I still have the curved life areas .

This bike.

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Old 07-10-2015, 09:14 AM   #8 (permalink)
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Perhaps another way to solve this would be to get a front trike. Like this: Trike Gas Motor Scooters 50cc 3 Wheels Moped

It's low and the double wheels in the front greatly improve stability. Don't know.
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Old 07-10-2015, 09:57 AM   #9 (permalink)
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Interesting but not available in Australia in that form or at that price !
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Old 07-10-2015, 04:12 PM   #10 (permalink)
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"Total Price: $1,758.00 + $399.00 Shipped!"

Normally, when I have seen people say "$x shipped," they refer to the cost, including shipping. $399 for shipping?

It kind of seems that if you want an Elio, you need to purchase one of these and build a body. Lower the seat like this guy: 214 mpg with DIY aerodynamic fairings on a Honda 125cc motorbike

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