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    Test: Aero Testing

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    Alex R
    **MicroMan World Record Holder**

    Posts : 353
    Join date : 2009-11-02

    Test: Aero Testing

    Post by Alex R on Sat Nov 07, 2009 12:48 am

    I am getting some data together about various things aero wise for my use in the future. The first test was Wheel cover (ie disc) V no cover and staying aero v not staying aero. Some of you may have read it before but some not. I am doing some other things tomorrow so will put them all together in this thread.

    Having been playing with a Power Tap for a while now I decided that it is just about a requirement for a race like Bussso so I went and got a wheel cover from Wheel Builder. It cost me $160 something OZ dollars when it finallly showed up on my credit card inclusive oof express postage from Fed Ex.

    As many tests are done at 40km/hr I am not so sure they give a legitimate idea of savings or not that can be had for the everyday Ironman athlete. As a 5 hour flat bike at Busso will put you in a very good place for a mid to latter 9 hour finish, I decided that 36km/hr was to be my test speed. It ended up being a little over that.

    Anyway, the test was three parts. Once with a wheel cover installed and position was sitting up and in no way aero to demonstate any power isssues you have by not staying aero. Second was Aero with Disc Cover and third Aero with NO Disc Cover. All three were done in stanndard raod riding kit and a normal road helmet. I paid close attention to the positioniing of my person on the bike with a few points of referennce for my hands, elbows and banus. The rest was just a matter of trying to hold a consistent speed and power output. All three tests were done in the same gear at 53/16 so that cadence variations would not have an influence on power. All data sampled was cut and pasted in WKO+ removing the period of acceleration and deceleration as I did an out and back course that was sheltered at each end and a cross wind section in the middle.



    Sit up with Cover

    Ave Speed 36.3
    Ave Power 283
    Norm Power 297


    Disc Cover Aero

    Ave Speed 37.0
    Ave Power 253
    Norm Power 260

    No Cover Aero

    Ave Speed 37.0
    Ave Power 260
    Norm Power 270


    These figures were then analysed a llittle further by a bloke called Alex Simmonds who is a bit of a power guru in OZ and he came up with.....

    I have made a few assumptions on conditions etc:
    Air density: 1.2 km/m^3
    Crr: 0.005

    Getting the exact assumptions may change the absolute values in the VE but not the shape of the plots.


    What this suggests is the following CdA values:

    Road Position and wheel cover: _ 0.370 m^2
    Aero with wheel cover : _______ 0.300 m^2 (81% of road CdA)
    Aero without wheel cover: _____ 0.315 m^2 (85% of road CdA, 105% of wheel cover CdA)

    On the basis of this limited data set, it suggest an approximate 5% improvement in aero from using the wheel covers.
    That is equivalent to ~ 1.5 seconds/km saving by using the covers.
    Compared to road position/no covers it's a saving of ~ 6.5 sec/km.




    Test tomorrow will be aero helmet v road helmet, spare tyre behind the seat v spare tube in rear pocket, tri suit v cycle jersey.
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    Alex R
    **MicroMan World Record Holder**

    Posts : 353
    Join date : 2009-11-02

    Re: Test: Aero Testing

    Post by Alex R on Sun Nov 08, 2009 1:40 am

    Stand by to stand by on this. Venue was not suitable.
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    Matt N

    Posts : 13
    Join date : 2009-11-02

    Re: Test: Aero Testing

    Post by Matt N on Sat Nov 21, 2009 7:48 am

    Standing by. Smile
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    Phill K

    Posts : 26
    Join date : 2009-11-05
    Age : 54

    Re: Test: Aero Testing

    Post by Phill K on Sun Dec 27, 2009 6:58 am

    Are we still standing?
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    Alex R
    **MicroMan World Record Holder**

    Posts : 353
    Join date : 2009-11-02

    Re: Test: Aero Testing

    Post by Alex R on Sun Dec 27, 2009 7:07 am

    Totally. Real world has me by the short and curlies. Probably another month or so until I can get some chance at this kind of thing. Maybe more. Moving to the other side of the world as we speak Smile
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    Matt C

    Posts : 116
    Join date : 2009-11-23

    Re: Test: Aero Testing

    Post by Matt C on Sun Dec 27, 2009 11:48 am

    oh you got that job did you?

    you going to be indoor training full time now or super climatised for the bid dance !
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    Alex R
    **MicroMan World Record Holder**

    Posts : 353
    Join date : 2009-11-02

    Re: Test: Aero Testing

    Post by Alex R on Sun Dec 27, 2009 11:26 pm

    It is 22 max there today Smile August is a whole different story though!

    For those interested, I am off to the middle East. Scord a gig with the UAE government working in Abu Dhabi. They were short a couple of Oil Billionaires but I just took the Air Traffic Control job. Am taking advantage of the Dubai World worries and living in Dubai as it is 45 minutes door to door to my work place and rents have halved the last 3 years.
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    Matt C

    Posts : 116
    Join date : 2009-11-23

    Re: Test: Aero Testing

    Post by Matt C on Mon Dec 28, 2009 12:13 am

    it better be port star quality
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    Cameron G

    Posts : 114
    Join date : 2009-12-10
    Age : 40
    Location : Quakers Hill, Sydney

    Re: Test: Aero Testing

    Post by Cameron G on Tue Jan 26, 2010 9:06 am

    Im ordering a set of wheel covers this week so if anyone wants to split the postage costs then send me a pm.

    [url="http://www.wheelbuilder.com/store/aero-disc-covers.html"]wheelbuilder site[/url]

    wheel covers
    $89.95 US per unit

    postage
    $77 for 1 unit (Scott has since told me he got the postage for $44 US, im assuming the cost of postage for multiple units will also drop.)
    $105 for 2 units
    $132 for 3 units
    $178 for 5 units
    $273 for 10 units.

    economy of scale.

    Im going to order on Friday which should get them here before Huskisson.

    pm if interested

    disclaimer: i have no affiliation with wheelbuilder.com.

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