Author Topic: frontal area questions  (Read 17922 times)

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Offline joea

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Re: frontal area questions
« Reply #30 on: October 14, 2010, 06:05:14 PM »
.....spell check......." a seeeeeething balm "

Offline racergeo

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Re: frontal area questions
« Reply #31 on: October 14, 2010, 06:24:47 PM »
  Come on guys lets keep this topic serious. So I built a model of my new liner and I put a straight piece of coat hanger into the top of it and I ran it through the bath water a few  times noting the deflection of the coat hanger. I build a bigger model and did the same thing and noted I had more deflection. What have I learned? And yes I carefully controlled the bath temperature.

Offline 1212FBGS

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Re: frontal area questions
« Reply #32 on: October 14, 2010, 06:25:34 PM »
geo
yes i also wonder what I'm gonna call that required number i need to input into my formula that I've been using for the last 30+ years.... the other 2 "programs" i use also require a number.... it seems the formulas all need a dimension as to how big a hole the turd (soothing word) pushes through the air...hummmm what shall we call it?..... OH! hey! how 'bout "FA"..... nah maybe to close to the banned word... any ideas?

Tortoise.... YES to both yer questions  :-D

Kent

Offline maguromic

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Re: frontal area questions
« Reply #33 on: October 14, 2010, 06:53:30 PM »
.....spell check......." a seeeeeething balm "

Never Kent :-D Tony
« Last Edit: October 14, 2010, 07:27:15 PM by maguromic »
“If you haven’t seen the future, you are not going fast enough”

Offline joea

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Re: frontal area questions
« Reply #34 on: October 14, 2010, 08:38:55 PM »
geo...the "wetted" area went up..

Offline racergeo

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Re: frontal area questions
« Reply #35 on: October 14, 2010, 10:26:56 PM »
  As I sit here in my bath, I'm thinking of Kent's Question as to what to call what was formally known as-------well, you know. I lack the education to come up with anything appropriate. Me thinks "turd" might not be universally accepted. There are other worrysome possibilities that could come out of all of Eric's Aerodynamicistic input into our little LSR world.
   What if Marlo Treit becomes so intimidated as to stop his project, rethink his aero package and instigate a series of changes that put Jim Hume years behind schedule?
    What if some day Blue's impute becomes so dominate as to require the SCTA to divide up the classes into two categories "Those Designed and recognised as being correct by Blue" and the antiquated old "intuitive, seat of the pants-gut instinct classes" Eric your original post stated you wanted to stir up some lively debate and so you have.

Offline joea

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Re: frontal area questions
« Reply #36 on: October 15, 2010, 09:57:20 AM »

The following are also "Blue's" comments...........


"""To be absolutely clear: I do not advocate outlawing anything"""

"""TEST!  There is absolutely nothing I can tell anyone about their car that is better than the data they can get for themselves"""

""Keep it coming everybody, and be critical too.  This is about safety and a broader understanding for everyone""

i remember when everyone told Ack he couldnt use "car" tires on his liner
and how it wouldnt work................


Offline Jonny Hotnuts

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Re: frontal area questions
« Reply #37 on: October 15, 2010, 11:51:40 AM »
I think I have a good idea what Blues' reasoning was behind 'forget Fa', ...I get ya buddy.

-however

Fa is a much easier concept for the non aero professional to understand and how affect its influence (make is smaller).
Fa does have an effect...maybe not as much as separated flow...but...ya know.

My problem is that I have never heard anyone discuss interference drag between the ground and the lower body surface. I would say these forces create a significant amount of overall drag.
Its one thing to design an airplane....but the interference drag created by the pressures off the ground add a new dimension that is misunderstood and NEVER discussed.
jonny_hotnuts@hotmail.com

"Sometimes it is impossible to deal with her, but most of the time she is very sweet, and if you caress her properly she will sing beautifully."
*Andres Segovia
(when Im not working on the car, I am ususally playing classical guitar)

Offline joea

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Re: frontal area questions
« Reply #38 on: October 15, 2010, 12:40:51 PM »
Johnny,  another Blue post about 3 yrs old....



"Preventing air from going under the car" is a combination of a good thing (negative alpha) and a bad thing (separation on the belly and tail).  If you can do it without adding weight, add a belly pan with a diffuser at the tail to reduce the separation and increase the negative alpha even more.  Then you can have the best of both worlds.  Lowering the whole car makes the effect greater at the risk of separation.  Where you go in height is more a function of how good your diffuser is at the tail and how much the extra drag costs you if you go too low and cause separation""

Offline Chris Horoho

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Re: frontal area questions
« Reply #39 on: October 15, 2010, 03:07:18 PM »
ok
i understand that
FA and aero are 2 different things but i still want to use FA to get an understanding of twhat i need to bring to the table
i do understand that i can only go so small and still have good aero but i have an idea but unsure if it will work as of yet

and for another ?
i read an old post that stated the FA of a 2x3 oval was 6'2"
my calcs might be wrong but i thought the area of a 2'x3' oval was 4.8 and that is the size i am shooting for to be honest

but again i do understand they arent the same but using both will let me know what i will need in HP and such
thank you for the posts and please keep the tech up
just guys lets keep it clean and not fight
everyone has an opinion and all are welcome by me
"Pinky"

Offline jl222

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Re: frontal area questions
« Reply #40 on: October 15, 2010, 03:49:44 PM »
 
  I'm always suggesting  Carroll Smith's books, in TUNE TO WIN. there's a good chapter on aero and on pg 84  he gives some numbers

  flat plate.. cd-1.5
  round tube     .60
  aircraft structural teardrop tubing  .06 :-o


                 JL222

     

   


Offline joea

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Re: frontal area questions
« Reply #41 on: October 15, 2010, 04:03:00 PM »

Offline Chris Horoho

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Re: frontal area questions
« Reply #42 on: October 15, 2010, 04:51:08 PM »
horoho...area calculations...

http://www.mathsisfun.com/area-calculation-tool.html


yes i am getting a similar number from the length
and a tad dif formula but close
oval and ellipse arent quite the same but i am probably leaning towards an ellipse in design anyways ??

thank you
i have no clue where the other gentleman got his numbers from then
it was in an older post on here but no biggie

i am a tool maker/machine shop owner and am fairly advanced in trig and geometry that was why i asked
to see if i was seeing things or if i was correct on my calculations
Thank you
"Pinky"

Offline WOODY@DDLLC

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Re: frontal area questions
« Reply #43 on: October 15, 2010, 05:02:33 PM »
Chris, start here: Aerodynamics For Racing and Performance Cars Hp1267 by Forbes Aird ($45~50)

A little hard to find but well worth it!  :cheers:

For more info and math:  :-D

Race Car Aerodynamics: Designing for Speed (Engineering and Performance) by Joseph Katz ($20~25)

or

Competition Car Aerodynamics: A Practical Handbook by Simon McBeath ($30)

For even more info and even more math:  :-o

Aerodynamics of Road Vehicles: From Fluid Mechanics to Vehicle Engineering ([Proceedings] / SAE) [Hardcover]
Wolf-Heinrich Hucho (Editor) ($100)

All available at Amazon.

They all "mention" frontal area - but oh well!  :?
All models are wrong, but some are useful! G.E. Box (1967) www.designdreams.biz

Offline Chris Horoho

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Re: frontal area questions
« Reply #44 on: October 15, 2010, 05:08:05 PM »
Chris, start here: Aerodynamics For Racing and Performance Cars Hp1267 by Forbes Aird ($45~50)

A little hard to find but well worth it!  :cheers:

For more info and math:  :-D

Race Car Aerodynamics: Designing for Speed (Engineering and Performance) by Joseph Katz ($20~25)

or

Competition Car Aerodynamics: A Practical Handbook by Simon McBeath ($30)

For even more info and even more math:  :-o

Aerodynamics of Road Vehicles: From Fluid Mechanics to Vehicle Engineering ([Proceedings] / SAE) [Hardcover]
Wolf-Heinrich Hucho (Editor) ($100)

All available at Amazon.

They all "mention" frontal area - but oh well!  :?
thank you
i will definitely be finding these and getting them when spare change is available
but thats just the fact of racing now isnt it lol
"Pinky"