Author Topic: Formula for aero drag.  (Read 16693 times)

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Offline robfrey

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Re: Formula for aero drag.
« Reply #30 on: November 06, 2013, 10:46:55 PM »
Sum,
From what I remember, Carmicheal does not bother with Cd at all. Can you confirm this Rex?
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Offline Jon

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Formula for aero drag.
« Reply #31 on: November 07, 2013, 05:50:43 AM »
Carmichael does talk of Cd; mainly wetted area and in conjunction with Reynolds numbers though.
Strojnik's books are an interesting read as well.
Also recommend Mike Arnold's AR5 videos.

jon
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Offline SaltPeter

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Re: Formula for aero drag.
« Reply #32 on: November 07, 2013, 03:05:14 PM »
       "Race Car Aerodynamics, Design for Speed" by Charles Katz----Joseph Katz--- Maybe

This is a great book and I've always wanted to meet Dr Katz as he has been a great asset to so many racers. I did think his book focused more on generating downforce than minimizing drag. I thought it to be a better book for SCCA racers than SCTA racers. Learned a lot from this book though.

It is the challange we face in our chosen Motorsport, and Dr Katz Book book reflects this as most Motorsport is about Down Force. It really helped me get my head around fundamental Aero and the way it it works on Vehicles.

"The Leading Edge" by Goro Tamai is about cheating the wind but not at the speeds we are aiming for. Again it helped me to understand Aero concepts, but I am still no Scientist.

This discussion is great, it's of great interest running a relatively Low Power Bike.... Aero is everything.

Pete  :-D

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Offline Rex Schimmer

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Re: Formula for aero drag.
« Reply #33 on: November 13, 2013, 08:07:25 PM »
Just a comment by Ron Ayers regarding the drag contribution of skin friction on the JCB car. He said that over 70% of the total drag at over 300 mph was contributed to skin friction. So things like fit, finish, body joint design and skin stiffness, which is especially critical on cars with flat sides or top, have a huge affect on the aero ability of any streamliner. Most top fuel bodies are made from .050 mag sheet and if you watch them at speed they are vibrating in and out at such a frequency and magnitude that there is no possible chance that they have attached air flow and attached flow, either laminar or turbulent is what you must have to be aero. If you look at the skins and inter support work on Marlo's liner you can see that Jim recognized this and provided a lot of support to prevent any skin deflections, I also think that he used .071 and thicker aluminum for skins which all help. (it also allowed him to really make the skins smooth and fit well by lots of filing with the "hungry file")

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Offline manta22

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Re: Formula for aero drag.
« Reply #34 on: November 16, 2013, 07:56:55 PM »
0.050 sheet magnesium is certainly light but it burns and then it's hard to extinguish.

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ

Offline wobblywalrus

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Re: Formula for aero drag.
« Reply #35 on: November 17, 2013, 12:57:25 AM »
It must be some sort of fire resistant alloy.  A person would be nuts to use the pure magnesium.

Offline robfrey

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Re: Formula for aero drag.
« Reply #36 on: November 28, 2013, 07:19:40 PM »
Jon,
I just ordered the first of the AR 5 DVDs. Can't wait to receive it! I will ask for some of the others for Christmas.
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Offline robfrey

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Re: Formula for aero drag.
« Reply #37 on: December 07, 2013, 04:27:12 PM »
Just received the first of the Arnold AR-5 videos. First one is titled "Why is it so fast", it is a great video! I highly recommend it!
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Offline tauruck

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Re: Formula for aero drag.
« Reply #38 on: December 22, 2013, 03:14:03 PM »
I spent time in the wind tunnel at the CSIR working as a subcontractor to a major manufacturer.

You won't believe some of the small insignificant things that affect aerodynamics.

Offline Glen

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Re: Formula for aero drag.
« Reply #39 on: December 22, 2013, 03:54:03 PM »
NHRA funny cars paint a fire resistaint coating inside the body, a few liners have done the same.
« Last Edit: December 22, 2013, 03:56:36 PM by Glen »
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Offline robfrey

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Re: Formula for aero drag.
« Reply #40 on: December 27, 2013, 10:50:08 PM »
Glen,
Tell me more about those paintable fire resistant coatings.
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