Author Topic: Butts Exposed,  (Read 15104 times)

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Offline stay`tee

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Re: Butts Exposed,
« Reply #15 on: March 08, 2014, 10:43:14 PM »
in the second photo its interesting to see the tapered sections in behind the riders legs, this area is always "dirty" when one has a run on salt that is a little wet,, ok, its a low pressure area,, "butt", the way i see it, by standing and raising your butt into the air is only increasing the low pressure area, :|,,
First Australian to ride a motorcycle over 200mph at Bonneville,,,

Offline Seldom Seen Slim

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Re: Butts Exposed,
« Reply #16 on: March 09, 2014, 09:58:54 AM »
Being the lanky kind of guy that I am - I always move around looking for the sweet position for my tuck.  I'm tall enough that if I want my helmet down hard on the deck/tank -- my butt is dang near sticking up into the breeze, not even touching the seat.  If I note the tach shows I'm slowing and I think it's from aero, not traction changes, I might try to get my butt on the seat - but then my helmet ends up being a bit higher and in the air.  If I try to keep as much weight as possible on the pegs, hoping to get more weight down low - then I've got my butt back up there.  And on and on.

Maybe if I get a legectomy and have them make it so I can take 6" or so out of my leg length before a run - maybe that'd help. :?
Jon E. Wennerberg
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Offline Stan Back

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Re: Butts Exposed,
« Reply #17 on: March 09, 2014, 01:09:52 PM »
You guise are reading the first photo rong -- it's a parachute pack!
Past (Only) Member of the San Berdoo Roadsters -- "California's Most-Exclusive Roadster Club" -- 19 Years of Bonneville and/or El Mirage Street Roadster Records

Offline Seldom Seen Slim

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Re: Butts Exposed,
« Reply #18 on: March 09, 2014, 01:19:20 PM »
Are you sure, Stan?  It looked too small to be a couple of 'em -- more like just one 'chute.*

* Pair-a-chute, get it? :roll:
Jon E. Wennerberg
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Offline Speed Limit 1000

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Re: Butts Exposed,
« Reply #19 on: March 09, 2014, 03:11:48 PM »
D@mn, Slim someone might want to chute U :-D
John Gowetski, red hat @ 221.183 MPH MSA Lakester, Bockscar #1000 60 ci normally aspirated w/N20

Offline floydjer

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Re: Butts Exposed,
« Reply #20 on: March 13, 2014, 11:03:47 AM »
Is this what one would refer to as "stand up" comedy?

Only if you are the butt of the joke. Tony
Couldn`t wait for friday could you ?..................
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Offline 1212FBGS

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Re: Butts Exposed,
« Reply #21 on: March 24, 2014, 10:28:37 PM »
Staytee.. the drag bike stepped seat was my brainchild... I developed it in the Texas wind tunnel back in 90 or 91 with Dave Schultz.... we were testing with smoke and I suggested he raised his butt up like we had been doing for years at Daytona and it greatly reduced turbulence and helped the air to reattach (only slightly as the area behind the rider is way too short to reattach and stabilize the turbulent air)... At Daytona you can pick up 500 rpm by raising your butt, but the butt raising at Daytona was not initially intended to benefit the rear air flow (that's a whole different story)... I applied this unintentional benefits and it worked in the tunnel so I began designing my drag race bodies with the step... then I designed them with different steps so the rider could move rearward on a loose track or forward if its hooking.... if the front fairing is designed right and the riders body is positioned correctly he doesn't need to raise out of the saddle... as a side note another thing we learned in the wind tunnel before Dave passed is that the "Aero hump" on the back of the leathers actually hurt air flow by reducing the negative air behind the riders helmet, that negative pulled the air flow down the riders back and helped reattached, without it the air just continued is tumble rearward.....
kent

Offline salt27

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Re: Butts Exposed,
« Reply #22 on: March 24, 2014, 11:53:20 PM »
butt raising at Daytona was not initially intended to benefit the rear air flow (that's a whole different story)... 
kent

Kent, You got me curious, would you mind elaborating on that "different story".

 Thanks, Don

Offline stay`tee

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Re: Butts Exposed,
« Reply #23 on: March 25, 2014, 01:03:25 AM »
Staytee.. the drag bike stepped seat was my brainchild... I developed it in the Texas wind tunnel back in 90 or 91 with Dave Schultz.... we were testing with smoke and I suggested he raised his butt up like we had been doing for years at Daytona and it greatly reduced turbulence and helped the air to reattach (only slightly as the area behind the rider is way too short to reattach and stabilize the turbulent air)... At Daytona you can pick up 500 rpm by raising your butt, but the butt raising at Daytona was not initially intended to benefit the rear air flow (that's a whole different story)... I applied this unintentional benefits and it worked in the tunnel so I began designing my drag race bodies with the step... then I designed them with different steps so the rider could move rearward on a loose track or forward if its hooking.... if the front fairing is designed right and the riders body is positioned correctly he doesn't need to raise out of the saddle... as a side note another thing we learned in the wind tunnel before Dave passed is that the "Aero hump" on the back of the leathers actually hurt air flow by reducing the negative air behind the riders helmet, that negative pulled the air flow down the riders back and helped reattached, without it the air just continued is tumble rearward.....
kent (quote)
 

Thankyou Kent for your deffinate answer,, your comments on the hump are also very interesting,, :cheers:
First Australian to ride a motorcycle over 200mph at Bonneville,,,

Offline Seldom Seen Slim

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Re: Butts Exposed,
« Reply #24 on: March 25, 2014, 04:51:49 PM »
Thanks for the better description of why the hump doesn't work, Kent.  I'd heard that -- but this is the first time I've seen any reasoning on why it don' work.  Maybe I'll take the hump stuffing out of my leathers this year and see what I find.
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Offline joea

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Re: Butts Exposed,
« Reply #25 on: March 25, 2014, 07:38:22 PM »
If u empty the hump please be careful what you do to the emty cargo space...

ask Pork Pie about ours...at over 250...i would elaborate but no one would believe it ...

High res shots at many per sec...were revealing and the look on Pork face was priceless...makes the ride super special

Offline 1212FBGS

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Re: Butts Exposed,
« Reply #26 on: March 26, 2014, 02:16:42 AM »
here is one pix that I found of Dave... I have 2 real good pix on one of my drives around here that shows smoke patterns with and without the hump..... one thing, if your back is up and flat and your tail corresponds well with the rider the hump does work... but if the windscreen is high, riders back rounded and low, she's no good.... unfortunately most "street bike" chassis puts the rider in a comfortable position that isn't good.... when I get some time ill write up about Daytona and air flow....
kr

well so much for that... I cant figger out how to post a that dam n pix.... back to work for me

Offline 1212FBGS

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Re: Butts Exposed,
« Reply #27 on: March 26, 2014, 02:17:26 AM »
oh..... well I guess it did post... haha
kr

Offline PorkPie

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Re: Butts Exposed,
« Reply #28 on: March 26, 2014, 06:53:30 AM »
If u empty the hump please be careful what you do to the emty cargo space...

ask Pork Pie about ours...at over 250...i would elaborate but no one would believe it ...

High res shots at many per sec...were revealing and the look on Pork face was priceless...makes the ride super special

Joe,

when I followed this thread I had your experience in my mind....tough.....
Pork Pie

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Offline maj

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Re: Butts Exposed,
« Reply #29 on: March 27, 2014, 05:05:37 AM »
 The clarity in PP's pics is hard to imagine before seeing them , and just what that clarity shows  :cheers:
Low pressure areas and turbulance esp