frontal area questions

[Dr Goggles]

Chris, start here: Aerodynamics For Racing and Performance Cars Hp1267 by Forbes Aird ($45~50)
A little hard to find but well worth it! 
For more info and math: 
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: 
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

Yep, check ,got 'em....some of them are about as relevant as a cook book for what we do, but at least they get you thinking.

I can hear a distant rumbling and I think it's Rex pulling his chair up to the computer to suggest Goro Tamai's book "The Leading Edge"...and it too is a weighty text but as I have said before ,do not attempt to operate machinery or complete difficult tasks after reading that book...it's not what you'd call a "page turner"

[joea]

horoho...re ""oval and ellipse arent quite the same""

http://mathforum.org/library/drmath/view/55402.html

[1212FBGS]

Hot nutz
There has been quite a bit of discussion about ground clearance of a race vehicle and quite a bit of research and testing done…. Actually Denis Manning gave a presentation at the 2nd symposium of automotive aerodynamics in the late 70’s about ground clearance and angle of attack… his finding was getting the vehicle up off of the surface…. And he still uses his findings on #7… also the Wixon brothers found during the Cal Tec wind tunnel design testing of the HD XR road race fairings the center of pressure and stability increased when the back of the fairing was lowered to the ground…. Contraire to the forward to rearward upward rake found on current racing vehicles trends…. Without skirts it will suck air under the vehicle….. So to answer your question with a typical Blue response, Ford or Chevy? You decide your own answer….
Kent

[interested bystander]

Goggles, your above post has to be best of the week!

I thot I was the only one beatin' up on Rex - for his spelling, damn engineers!

 Couple of points, since Blew seems to be in the barrel these days. Don't know how you can dimensionally compare objects without reference to FRONTAL AREA.

Is CdA meaningless?

An amazing fact is 48 year old Bloo mentioned "WE" in reference to the "elimination" (my word) of the term frontal area in Aerodynamics. He said it had been ignored for 60 years.

That may be a record for IN-UTERO experience!

[Chris Horoho]

horoho...re ""oval and ellipse arent quite the same""

http://mathforum.org/library/drmath/view/55402.html

http://www.spectrumanalytic.com/support/library/ff/area_calculations.htm      (look half way down or so)

[Chris Horoho]

horoho...re ""oval and ellipse arent quite the same""
http://mathforum.org/library/drmath/view/55402.html

http://www.spectrumanalytic.com/support/library/ff/area_calculations.htm      (look half way down or so)

This wasnt meant to be a smartie responce just stating what ive been taught
An oval is 2 half circles with straight sides and an elipse is a circle looking at it at a 45 degree angle (or which ever angle to give set length)

[Chris Horoho]

And to the fa not being needed i will say this and hope i dont stir up to many people
But you cant push a 747 on the ground to high speeds (even though fairly aerodynamic) with just 500 hp

[wobblywalrus]

Chris, during lunch break a person can learn a lot by typing a subject like aerodynamics into a search engine and reading a little bit each day.  There are some government sponsored sites dedicated to teaching teenagers about aero.  NASA has one.  Those are pretty good reading.  A worldwide search will bring up the British web sites and there is a lot of info there.

[Rex Schimmer]

A big thanks to Dr. Goggles for getting a remark in on my favorite "aero" book, "The Leading Edge" ! Yes it is "challenging" reading and yes it is about cars that only go 50-60 mph, sun racers, but it addresses more of the details that we need to be interested in if we are going to build an efficient aerodynamic car than any other book I have seen. I have a copy in my shop, next to my bed and in the "reading room" and I re-read and review it all of the time. Maybe I need to stop reading and start building!!!

Just a comment on most of the present day cars that are running at the 400 mph area and also I include Marlo's car, if you look at them most of them are the same basic shape, some sort of pointed nose, a square cross section, long flat sides and some sort of shaped tail that closes out the rear of the car. Only the Spectre car, and Al Teague's (I know the spelling is wrong!) diverge from this general "formula". I think that the new car that is being designed  by Rob and Woody (with help from Blue)  is a true step away from the standard formula and I, for one, am wishing them the greatest success. Also if you look at the three leading motorcycles all of them are built along the lines that Blue is suggesting, not a flat bottom in the bunch.

Just a note on the Cd vs the "wetted area" conflict, I read an article in the magazine "Bernoulli" by the aero dynamisist  for the JCB diesel car and he said that 75% of the total drag on that car was skin friction which is directly related to wetted area.

Rex

[comp]

horoho...re ""oval and ellipse arent quite the same""

http://mathforum.org/library/drmath/view/55402.html

 saved link ,,thanks

[maguromic]

Rex, Is "Bernoulli" still in print?  I loved that magazine, but it had sporadic distribution.  Tony

[Rex Schimmer]

Tony,
I just received my latest issue of "Bernoulli" last week, 2 1/2 years after my first issue. Now that The Automotive Book Store in Burbank is closed you can probably only get it by subscription.

Rex

[John Burk]

With fast streamliners there are so many variables it's not easy to rate body shape by mile times

John Burk .

[WOODY@DDLLC]

I just received my latest issue of "Bernoulli" last week, 2 1/2 years after my first issue. Now that The Automotive Book Store in Burbank is closed you can probably only get it by subscription.

Bernoulli is struggling! My March issue arrived end of last month. All the staff tells me is, "It's coming next week!" Don't know if I will get all my subscriptions or not! Any back issues you can find are worthwhile reading.

A big thanks to Dr. Goggles for getting a remark in on my favorite "aero" book, "The Leading Edge"!

This is a good primer before trying to absorb all of "The Leading Edge": The Winning Solar Car: A Design Guide for Solar Race Car Teams - by Douglas R. Carroll ($50 - discount for SAE members.) An old(er) billiard instructor once told me there is a time to theorize and then you just have to bend over and shoot!


With fast streamliners there are so many variables it's not easy to rate body shape by mile times.

Cheese Louise, how many ways are there to go 200+, 300+ or 400+? Why just look at LSR! Balance all the factors and a brick with wheels can go 304+!  Too many (unbalanced) rules will always stifle innovation. Every safety rule written is based on an actual event and an overreaction by the governing body! In order to achieve a good balance my personal LSR design mantra is S³. Safety, Slippery and Small in THAT order but there is always more than one way to skin a water buffalo! [Of course the water buffalo doesn't like any of them! ]

That's my rant - for now!

[55chevr]

Woody ... interesting perspective ... frontal area / coefficient of drag / different design arguments and then an open wheel roadster goes 304 ...

Joe