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post #1 of 18 (permalink) Old 07-29-2007, 09:50 PM Thread Starter
 
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alpinestar jacket

i was just woundering if any one out ther has the alpinestars s-mx air-flo leather jacket? the jacket has a hump on the back which im guessing is for wipelash or something like that. does any other jackets have that besides alpinestar?
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post #2 of 18 (permalink) Old 07-30-2007, 12:16 PM
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Originally Posted by dlynch View Post
i was just woundering if any one out ther has the alpinestars s-mx air-flo leather jacket? the jacket has a hump on the back which im guessing is for wipelash or something like that. does any other jackets have that besides alpinestar?
I think it's more of an aerodynamic gimmick. Look at almost any racer, and you'll see it. Pretty sure it was a big fad in street jackets just a few years back.

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post #3 of 18 (permalink) Old 08-01-2007, 02:35 PM
 
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its just aerodynamics. the same logic behind the hump on the back of the jacket is incorporated into the seat bubbles that fit over the 2nd seat on the back of the back. the smoother the air transition going over your head and down the back of the bike, the less air drag.

its why dragsters have a flat spoiler often times that extends behind the rear bumper on top of the trunk.
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post #4 of 18 (permalink) Old 08-01-2007, 06:04 PM
 
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It is just for aerodynamics, but a lot of them also double function as a rigid back protector. And that is a nice jacket you're considering, albeit an extremely expensive one...

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Originally Posted by ptowntsi View Post
the smoother the air transition going over your head and down the back of the bike, the less air drag.

its why dragsters have a flat spoiler often times that extends behind the rear bumper on top of the trunk.
No, the purpose of spoilers on cars has nothing to do with drag (Most spoilers actually increase drag, not decrease it.), it has to do with lift/downforce. The purpose of the spoiler is to create negative lift, i.e. downforce, in order to push the rear of the car down into the ground to maintain traction and increase high speed stability.

These jacket humps are doing something entirely different than that, but you were right about their intended purpose, just not the spoiler's intended purpose
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post #5 of 18 (permalink) Old 08-01-2007, 06:14 PM
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[QUOTE=ceo012384;402016]


No, the purpose of spoilers on cars has nothing to do with drag (Most spoilers actually increase drag, not decrease it.), it has to do with lift/downforce. The purpose of the spoiler is to create negative lift, i.e. downforce, in order to push the rear of the car down into the ground to maintain traction and increase high speed stability.
[QUOTE]


oooohhhhh. damn, that sounded good.

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post #6 of 18 (permalink) Old 08-01-2007, 06:15 PM
 
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Originally Posted by ceo012384 View Post
It is just for aerodynamics, but a lot of them also double function as a rigid back protector. And that is a nice jacket you're considering, albeit an extremely expensive one...



No, the purpose of spoilers on cars has nothing to do with drag (Most spoilers actually increase drag, not decrease it.), it has to do with lift/downforce. The purpose of the spoiler is to create negative lift, i.e. downforce, in order to push the rear of the car down into the ground to maintain traction and increase high speed stability.

These jacket humps are doing something entirely different than that, but you were right about their intended purpose, just not the spoiler's intended purpose
its more for areodynamics the turbulents behind the helmet will pull on your body and lift u up at high speeds
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post #7 of 18 (permalink) Old 08-01-2007, 06:17 PM
 
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the old mustang fastbacks would reach speeds of 125 or better the back wheels would lift off the ground and spin the car around
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post #8 of 18 (permalink) Old 08-01-2007, 06:18 PM
 
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oooohhhhh. damn, that sounded good.
Nothing like a little technobabble to make ya sound smart
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its more for areodynamics the turbulents behind the helmet will pull on your body and lift u up at high speeds
The turbulence (or turbulent eddies, more specifically) of air behind a helmet are generally not strong enough to pull a person's body up at all of lift you up... they do, however, make a large region of negative pressure and lots of drag. The aerodynamic benefit of the hump is just to smooth things out so the air flow doesn't separate from the body as it flows around it. Separation leads to turbulence and drag = bad.

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the old mustang fastbacks would reach speeds of 125 or better the back wheels would lift off the ground and spin the car around
Perfect example of the effect I was talking about

Last edited by ceo012384; 08-01-2007 at 06:33 PM.
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post #9 of 18 (permalink) Old 08-01-2007, 06:31 PM
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Originally Posted by ceo012384 View Post

The turbulence (or turbulent eddys, more specifically) of air behind a helmet are generally not strong enough to pull a person's body up at all of lift you up... they do, however, make a large region of negative pressure and lots of drag. The aerodynamic benefit of the hump is just to smooth things out so the air flow doesn't separate from the body as it flows around it. Separation leads to turbulence and drag = bad.
:
'turbulent eddys'

there ya go again.

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post #10 of 18 (permalink) Old 08-01-2007, 06:33 PM
 
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'turbulent eddies'

there ya go again.



I'm a nerd
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post #11 of 18 (permalink) Old 08-01-2007, 06:50 PM
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I'm a nerd

nah, you just know yur $h!t.

anyway back to the jacket.....
great jacket, just too rich for my blood.

and jackets with the hump, is just overkill for the streets.

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post #12 of 18 (permalink) Old 08-01-2007, 07:28 PM
 
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and jackets with the hump, is just overkill for the streets. [/QUOTE]

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post #13 of 18 (permalink) Old 08-01-2007, 08:20 PM
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the old mustang fastbacks would reach speeds of 125 or better the back wheels would lift off the ground and spin the car around
Never seen that, but my parents' '67 coupe gets light in the nose after about 65mph.

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Originally Posted by ceo012384 View Post
Separation leads to turbulence and drag = bad.
That's why supersonic aircraft do not use the normal cylindrical fuselage and flat wing design. It's not aerodynamically optimal...ever...just easier to build. A better design (for bikes too) is similar to Buell's "backward arrowhead."

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post #14 of 18 (permalink) Old 08-01-2007, 08:26 PM
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Originally Posted by Phenix_Rider View Post
Never seen that, but my parents' '67 coupe gets light in the nose after about 65mph.
Install a fat swaybar I put one off a trans am on my 72 cutlass n you would be amazed how that help its handling n staability
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post #15 of 18 (permalink) Old 08-03-2007, 02:18 PM
 
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Originally Posted by ceo012384 View Post
It is just for aerodynamics, but a lot of them also double function as a rigid back protector. And that is a nice jacket you're considering, albeit an extremely expensive one...



No, the purpose of spoilers on cars has nothing to do with drag (Most spoilers actually increase drag, not decrease it.), it has to do with lift/downforce. The purpose of the spoiler is to create negative lift, i.e. downforce, in order to push the rear of the car down into the ground to maintain traction and increase high speed stability.

These jacket humps are doing something entirely different than that, but you were right about their intended purpose, just not the spoiler's intended purpose

yes but in the case of the cars i'm talking about it does not add downforce.



also on the 4 runner, these were put on them to reduce drag from slower air 'dragging' down the back of the SUV, this spoiler flips the air stream up, and then down keeping it off the rear body.

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post #16 of 18 (permalink) Old 08-03-2007, 03:25 PM
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Originally Posted by PlayfulGod View Post
Install a fat swaybar I put one off a trans am on my 72 cutlass n you would be amazed how that help its handling n stability
It handles great- dad ran SCCA (solo2) autocross with it for a while. The nose just picks up on interstate runs. Makes for a weird floaty feeling.


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Originally Posted by NONE_too_SOFT View Post
All riders take risks- what you wear usually reflects your respect for the bike and general knowledge of riding.
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post #17 of 18 (permalink) Old 08-04-2007, 01:28 AM
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Quote:
Originally Posted by ptowntsi View Post
also on the 4 runner, these were put on them to reduce drag from slower air 'dragging' down the back of the SUV, this spoiler flips the air stream up, and then down keeping it off the rear body.

Actually, you are half right. On most SUV's with the rear spoiler, it is there to split the air, half goes up to smooth the air stream, but some is forced down to help keep the rear glass clean. It only works [email protected] but thats the engineers intended idea.

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they make the one i posted in a strap on version
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post #18 of 18 (permalink) Old 08-13-2007, 03:51 PM
 
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i have the black one, i love it...fits awesome and got it from a supporting vendor that price matched and i got it for a lot cheaper than advertised. It zips into my alpinestar track pants as well....just an awesome jacket i love it

ill post some pics later
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