SuzukiHayabusa.org
GENERAL => MAXIMUM OVERDRIVE => Topic started by: Frank06 on May 26, 2017, 09:12:26 PM
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Does anyone have any data on performance where the only difference is addition of APS type tail section? How much faster, whose bodywork. Etc.
Thanks very much!
Frank
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Here is what I do know: there is a huge negative and turbulent pressure area behind the rider. The more extended and especially the more enclosed the tail, that area is moved back and down away from the bike. You can see the manufactures do this over time with the 1000 bikes, while the tails are not enclosed they have moved them back further and higher. IIRC, I was at Maxton in '09 (?) when Bill ran a 250-ish, he went directly to the pits and put on his "street" bike tail and on his next pass ran a 270+ without any other changes.
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I think the biggest troubles with the extended LSR type tails are if you have separation of the airstream behind the rider and loose laminar flow the big tail is a large area to catch the Karman vortex street generated after the separation (google it )
It is very apparent on the salt , but more hidden on the black top
some of the more successfull bikes on the salt use a short tail , it reduces drag without the disadvantages of the large side area
I am still trying to get a larger tail to work , i see a potential 20-30mph advantage over a non enclosed tail when its done right, just look at Ralph Hudsons APS1000 as an example of a long tail bike, and Al Lamb as the short tail example
And this is even before you look at cross wind effect
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Here is the example of a Karmen Vortex Street https://en.wikipedia.org/wiki/File:Vortex-street-animation.gif
you can see it in the salt and dust trails on video of ElMirage and Bonneville , and you can most definitely feel it
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Thanks for the info. I found a pic of Al Lamb's bike here https://cdn-4.motorsport.com/static/img/amp/400000/430000/439000/439700/439764/s6_20421/bike-al-lamb-land-speed-record-2013-al-lamb.jpg. He's running MPS but it's clear how the additional bodywork covers more of the rear wheel area.
Ransom: are you saying that when Bill switched to a shorter tail that he went faster? Do you remember if this was the configuration? https://postfeed.net/wp-content/uploads/2017/03/13-8-550x361.jpg
Maybe the title of the thread should be "stock bodywork versus APS"...
(thanks)
Frank
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IIRC, he switched from a stock tail to his "street bike tail" as shown in that picture. I believe (now it is hard to recall from 8 years ago and not knowing the significance of those runs) that he had the front fairing on the bike for both runs.
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My honest opinion is that it is difficult to get good track data from aero changes due to the ever changing conditions. Without renting a track for a private (or semi-private) event, you really can't get back to back passes and even if you could, weather conditions can change that quickly to skew the data.
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That's a really good point, a few mph headwind can easily negate any improvements. I'm casting about for simple aero mods for the E-Busa to see if I can pick up a few mph this summer, I was thinking of going whole-hog with enclosed tail but that's not really compatible with a street bike, lol.
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Maybe "Resistance" is the key :wink:
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"Resistance is Futile. You will be assimilated."
Happened long ago, lol. :bike:
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"Resistance is Futile. You will be assimilated."
Happened long ago, lol. :bike:
And thats the truth, I was assimilated many years ago when I cobbed a old corvair turbo on my Honda single cam 750, would not start well, would not idle well, would not do part throttle much at all.......but when you went wide open and it cleared up that when I was first addicted (assimilated) to boost
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With speeds in excess of 200mph most have handleing problems when thay use the enclosed tail, however oem tails and also tail sections with cutouts (MPS) always handle well,,
Disturbed air, "resistance" behind the rider/machine, imho, plays a part in the bikes stability,,,
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My honest opinion is that it is difficult to get good track data from aero changes due to the ever changing conditions. Without renting a track for a private (or semi-private) event, you really can't get back to back passes and even if you could, weather conditions can change that quickly to skew the data.
you can nearly get back to back runs at the fall race at loring on sunday.
http://docs.wixstatic.com/ugd/3bd111_725c5d70bdc745b7bfca5885db2c0c88.pdf
Greg Neal had 27 runs, Jimi Heyder had 39....
i want to take a short tail for my bike to test. the longer one seems to be affected by crosswinds and i dont like running in those anymore. if a run feels weird i abort. maybe the short one wont feel funny?
(https://scontent.fybz2-1.fna.fbcdn.net/v/t1.0-9/13754302_10154320153971948_1539244172530478790_n.jpg?oh=208e579bc5723b1df9bf77a205a0e7f1&oe=59E4CB36)