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Discussion Starter · #1 ·
Bibliography

The best reference I've seen is Motorcylce Design and Technology, Gaetano Cocco, Aprilia Press. The section on aerodynamics is simply great, and everything you ever wanted to know about moto design is there. I got my copy through Amazon.
 

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I’m surprised that we haven’t seen more radical attempts at streamlining from the world of Moto GP. After all, it is basically prototype racing. I would at least expect to see fully faired in wheels and hind quarters. Apparently, like in Formula 1, there are rules that stipulate that the wheels and ****pit must remain open. Does anyone know if there is any truth to this?
 

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I believe that, simply put, 50% of the front wheel and 50% of the rear wheel must be visible when viewed from the side. With elimination of this rule, you can quickly envision a fairing that totally encloses the wheels and the rider. A retractable strut (landing gear) can be used to hold the bike upright at a stand-still. After all, if things go according to plan the bike should only use the strut once per race. Aerodynamics and safety should improve with the rider strapped into a cocoon (no more highsides!). Fire suppression and rider egress becomes more important, however.
 

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Discussion Starter · #4 ·
Sorry, but the rules also say the rider's legs may not be exposed or impeded. The air flow needs of the intake, cooling and braking systems must be addressed. Full streamlining only works for land speed record bikes and they are incredibly unstable and dangerous.



Being strapped into a cocoon will appeal to few racers I'm afraid. That's a different sport.

Aprilia is addressing what they can do under the rules:

1) Lower the center of pressure and reduce the drag coefficient to control pitch

2) Improve integration of the rider profile with the fairing and seat back

3) Reduce or eliminate front wheel lift

4) Move the center of pressure back (fin?)



They have great engineers!
 

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Don't forget that riders use their bodies to assist in braking by sitting up before a corner. A fully enclosed rider couldn't stop as effectively and would be susceptible to late braking passes all the time (assuming the unfaired rider could stay close enough).
 

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You must be joking about being "strapped into a cocoon." Ask yourself if you want to be strapped to your bike when it goes down. Something tells me you won't get a roll cage with your cocoon idea, so its best not to be strapped to the motorcycle.



BTW, the physics of a "highside" will not go away with a cocoon. As long as tires still slide, highsides(and subsequent crashes) can happen.
 

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Re: Bibliography

I wasn't really all that impressed with Motorcycle Design and Technology. I don't know if the problems are with the original text or the translation (assuming this is a translation) but the book needed a severe technical editing. The technical discussions did not unfold in a logical sequence. When read carefully, some of the equations in the chasis chapters were wrong, when compared to the prose. The discussion of tire slip was beyond understanding. I have BS and Master's degrees in Mechanical Engineering, and have plowed my way through some poorly written text books. This was by far the most poorly written technical book I have every read. If he was trying to write a book to explain the basics of how a bike works to a lay audience, he used too may equations (aside from them being wrong and poorly presented). A motorcycle version of "The Way Things Work" would have been a better approach. If he was trying to write a text book (which he claims he is not) he needs to learn how to write for a technical audience. As is I found this book had very little value to the reader beyond the great cover.
 

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Excuse me, am I missing something here? Isn't a motorcycle supposed to be an open air, freedom inspiring commune with nature, speed and the mind/body/spirit? Presumably, manufacturers race to sell. Do you want to be putting around your neighborhood in a cocoon? We motorcyclists continually deride cars as cages, and the people who drive them less than fondly. Yet, we are writing about cocoons for our heart's delight? Gimmie a "real" motorcycle please--plenty of sound and wind, so I will be certain that I have escaped the clutchs of society for at least a few moments, and that I will be absolutely certain that I'm on a motorcycle. Better to be run over and killed by a socer mom than ride around in a cocoon, or anything remotely resembling a set up like that. Just one person's view.
 

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Re: the open air

Yes, you're absolutely right about the point of motorcycling in general.

However that's not particularly relevant in the scheme of aerodynamics at the top level of motorcycle road racing. There is one big reason why GP bikes cannot touch F1, prototypes (le Mans), and so on-- aerodynamics. Too much drag for the power they make and no downforce. Without downforce they can't touch the cornering or braking of the elite 4 wheeled vehicles.

-Colin
 

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Re: the open air

But I think you miss the point. Every motorcycle manufacturer will tell you that they race to sell bikes in the showroom and to improve their product to that end. The few that want to walk on the edge can finance themselves with money from frustrated rich old men like they always have, and turn up at places like the salt flats. None of this has anything at all to do with retail motorcycle sales--but rather a fringe element interested in pressing the envelope. Granted, we need those, but not in motorcycle manufacturing. For instance, do you think that Ducati knows anything about aerodynamics when they use the wind tunnel facilities of Ferarri? When a showroom motorcycle that anyone out there can buy--blows away a Vette in any measure of performance--where is the argument for even more? My point being that a motorcycle to me is an open air vehicle. Using the cutting edges of design and aerodynamics in that context, seem appropriate to me. But, stuffing somebody inside a cocoon--gimmie a break.
 

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Re: Bibliography

Steve, any other suggestions on books to look for on these topics? I'm not going to shell out the cash for an inferior book. BTW, I'm an undergrad student with just a few quarters of physics under my belt. I ain't got no masters.
 

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Discussion Starter · #15 ·
Re: Bibliography

You said some of the equations in the chasis chapters were wrong, when compared to the prose.

I checked out most of the equations and found problems only with the symbols. Translation appeared to be pretty terrible, but decipherable.

I have developed a hefty spreadsheet to model motorcycle performance. Using some additional parameters from the book improved it a lot.

As a reference it works just great for me. It could be much better, but it's the best I've found. Can you suggest anything?
 

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Discussion Starter · #16 ·
Re: the open air

Downforce that increases grip is the resultant force perpendicular to the pavement. Aerodynamic forces from the motorcycle shape are directed according to the lean angle. Attempts to increase aerodynamic downforce have decreased straight line speed for a very small increase in cornering grip and a huge loss in cornering stability.

Four wheel vehicles can keep the bodywork close to and parallel to the pavement. Motorcycles can't.
 
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