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Author Topic: 200MPH Vintage Class Bike Build  (Read 19395 times)
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tortoise
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« Reply #15 on: December 23, 2016, 08:08:01 PM »

In the basic HP required to go fast (BHP= Cd x Frontal area x (speed to the third power)/146600) Frontal area is in sq. feet and speed is in MPH. The relation ship between HP and CdA is equal, that is 50% more Hp is the same as 50% less CdA. I have always felt there are three types of guys at Bonneville, motor guys that just keep throwing HP at it, aero guys that go faster by better aero and then there are the "Really Fast Guys" they do both!!!

Rex
100% more Hp is the same as 50% less CdA. (Or 50% more Hp is the same as 33 1/3% less CdA).
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Frank06
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« Reply #16 on: December 23, 2016, 08:29:40 PM »

Tom - have you measured the frontal area on your bike?  For sure good aero is the most elegant way to get there.
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saltwheels262
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« Reply #17 on: December 23, 2016, 08:57:35 PM »


and I'll bet on you getting there..


So do I !!
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bub '07 - 140.293 a/pg   120" crate street mill  
bub '10 - 158.100  sweetooth gear
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'16 -- 0 runs ; 0 events -- made a 2 state change in ZIP codes

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astek
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« Reply #18 on: December 23, 2016, 11:16:40 PM »

Yes "The Baron" my frontal area is 547.78 square inches (3.8 sq.-feet). I hope I will have less than .4 cd. 
Are there any APS bikes with less than  .3 cd?
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Vinsky
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« Reply #19 on: December 24, 2016, 01:17:41 AM »

If you can navigate this website, it has some pretty neat designs for bodies. It's Italian but can be translated to english.
http://lnx.recordmotorcycles.com/
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John
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« Reply #20 on: December 24, 2016, 05:12:24 AM »

Have you looked at Tom Mellor's bike?
I would guess that an old Triumph Trident wouldn't make much more than 100hp
and I think he went 200 this year

   Bones
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Frank06
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« Reply #21 on: December 24, 2016, 08:57:12 AM »

Tom's bike is pretty well done.
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Frank06
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« Reply #22 on: December 24, 2016, 11:48:20 AM »

Here's what it looked like at BMST this year.

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TheBaron
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« Reply #23 on: December 24, 2016, 12:28:56 PM »

Hi Again Alp,,,

I don't have any hard numbers on other APS bikes,,, as an educated guess ,,, maybe a few get down to Cd of .300 but I think most don't....

Cd of .400 is quite doable,,, I'll be glad give you advice on how to fine tune your aero package when you get to that point....

This is an area I know a little about...........

Best of Fortune to us all in the 2017 Season,,

Robert
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Koncretekid
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« Reply #24 on: December 24, 2016, 02:13:52 PM »

In response to Frank's question, here is a pdf of my bike which seems to be around 4.3 sq ft. According to Rex's post, my CdA must be around 2.17 which indicates that my Cd is around .5, though it looks better than that.
Tom

* Land Speed Frontal - outline.pdf (13.41 KB - downloaded 71 times.)
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We get too soon oldt, and too late schmart!
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« Reply #25 on: December 24, 2016, 03:15:15 PM »

. . . the sitting ergonomics, side cut off, is something never done before, I think it will make a difference in aero.
Do you have a sketch of this?

tortoise, this is the bike I have designed. The uncomfortable sitting position reduces the cut off area and there are no gaps between body parts, you pull your knees all the way up to your chest and line them up with your elbows, your feet are right under your butt with top off feet facing downwards and toes facing backwards (see lower rear cut off shape). The idea is when you crash you will eject and not get stuck in the bodywork.


Tom's bike is pretty well done.

Great bike!

"TheBaron" Thank you,


* 2017 APS study 2 Converted.jpg (42.87 KB, 1200x431 - viewed 120 times.)
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Seldom Seen Slim
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« Reply #26 on: December 24, 2016, 03:26:24 PM »

Can you breathe well enough in that position for the 2 or three minutes it's going to take?  I know that I'm short of breath by the time I'm at the 5 - and my tuck isn't nearly that radical.

Like the car guys say about designing so there's room for you with the safety gear -- I'll suggest that you try wearing your gear and scrunching up and see if maybe a breathing exercise routine is in your future.
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Jon E. Wennerberg
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Koncretekid
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« Reply #27 on: December 24, 2016, 04:58:50 PM »



Interesting comparison.  But I think you're going to have to hire one of those horse racing jockeys to fit in that space!
« Last Edit: December 24, 2016, 05:07:38 PM by Koncretekid » Logged

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tortoise
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« Reply #28 on: December 24, 2016, 05:17:07 PM »

Can you breathe well enough in that position . . .
Scrolling at the top of his web page, there's a little photo of his 175 mph bike being ridden in a full tuck in a similar position.


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TheBaron
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« Reply #29 on: December 24, 2016, 05:19:47 PM »

Tom,,, your BSA is very well done  if you are getting 143 mph from 45 HP.. I estimate your Cd to be less than .440...

The Suzuki Hayabusa is the best aero street bike around and its Cd is in the .56 range.....

My Morini has 6.25 sq ft of frontal area and a Cd of about .485 with just its road race fairing and large aero front fender...

It runs 123-124 mph at El Mirage  from its little gasoline powered pushrod 350 motor

I'm working on a large tail package for next year to get the Cd down some more...

Robert
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