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Old 08-18-2011, 04:25 AM   #21 (permalink)
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Quote:
Originally Posted by euromodder View Post
http://ecomodder.com/forum/showthrea...rt-c-9287.html

You can cut it off at the wanted length - beyond 70% the gains are minimal anyway.


In that case, you'll have to live with the resulting height.
Thanks for that link ...I read a bit and am trying to understand but my engineering knowledge is pretty slim and those fellas are pretty good at it .I can't even understand the units !

I did note the template though ,my idea seems reasonable within those parameters .

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Old 08-27-2011, 06:58 AM   #22 (permalink)
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I've just modified the drawing a little , relieved the area between the rider and screen and added area to the top rear .

How does that look ?

I scrounged a bit of surf board foam last week to make a model from .How do you think she would handle cross winds ?
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Old 08-27-2011, 07:03 AM   #23 (permalink)
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This looks interesting ,about half way down the page .
Tony Foale Designs, article on motorcycle aerodynamics.

It explains how a well faired teardrop shape develops side forces in a wind even at 15 degrees off straight ahead .Not encouraging !

There appears to be a case for a straight sided fairing or at least one that doesn't generate a side force .

Last edited by PeterS; 08-27-2011 at 07:44 AM..
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Old 08-27-2011, 08:30 AM   #24 (permalink)
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Perhaps scallops in the sides of the fairing to break up lift ? The standard aero template needs spoiling I think .A strange idea but the article I linked above points out some serious problem for a standard aero pattern on a bike .

The scallops could still allow good airflow over the body , perhaps not ideal but without the side lift .
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Old 08-28-2011, 05:47 AM   #25 (permalink)
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This picture seems to show the problem pretty well .



It seems that spoiling the aero shape (which would be a horrible pity !) or alternatively leaving a gap between the forward and aft section....it would allow the pressures to equalise across the body and stop there being any side lift .There would still be the straight side pressure but not aero side lift .That might more than half the side forces .

Any comments on this ? I'm just thinking but if anyone can point out my errors I would be pleased and grateful !
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Old 08-28-2011, 07:42 AM   #26 (permalink)
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Here's another modification, the 2 lines represent the opening in the side, the rear would still move backwards 12 inches or so on draw slides to make getting on easier .

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Old 08-28-2011, 11:33 AM   #27 (permalink)
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Quote:
Originally Posted by PeterS View Post
This looks interesting ,about half way down the page .
Tony Foale Designs, article on motorcycle aerodynamics.

It explains how a well faired teardrop shape develops side forces in a wind even at 15 degrees off straight ahead .Not encouraging !

There appears to be a case for a straight sided fairing or at least one that doesn't generate a side force .
All bodies EXPEREANCE forces from all directions, the forces they generate are the reaction forces. The question you need to ask yourself is what are they, and how are they managed! Make your self a free body diagram and study it to find the forces and reaction forces. An other thing you might try is accurate description of what actually happens when forces are applied.
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Old 08-28-2011, 12:02 PM   #28 (permalink)
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Quote:
Originally Posted by PeterS View Post
This picture seems to show the problem pretty well .



It seems that spoiling the aero shape (which would be a horrible pity !) or alternatively leaving a gap between the forward and aft section....it would allow the pressures to equalise across the body and stop there being any side lift .There would still be the straight side pressure but not aero side lift .That might more than half the side forces .

Any comments on this ? I'm just thinking but if anyone can point out my errors I would be pleased and grateful !
The diagram and description are very poor. What you need to know is what are the forces and how do they change for each body. The wing shaped body may only experiance a very low force in the direction of travel and any change in angle of attack will have a proportionally larger change in net force, yet the total force on the body is still less than the force on the rectangle shaped body. So with out some numbers and better explenation you have confusion, rather than understanding.
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Old 08-28-2011, 12:17 PM   #29 (permalink)
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Quote:
Originally Posted by PeterS View Post
This looks interesting ,about half way down the page .
Tony Foale Designs, article on motorcycle aerodynamics.

It explains how a well faired teardrop shape develops side forces in a wind even at 15 degrees off straight ahead .Not encouraging !

There appears to be a case for a straight sided fairing or at least one that doesn't generate a side force .
When you find a straight sided fairing that that does not "generate" side force please let me know. That way I could make that the front of the motorcycle and have no aerodynamic drag force at all.
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Old 08-28-2011, 01:04 PM   #30 (permalink)
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PeterS, I think Tony Foale already explained it in his article - the side forces are counterbalanced by leaning the cycle into the wind.

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