World's lowest drag vehicle

[Ratliff]

OK Blue time for some definition of terms. Fines ratio: If I make my body as a body of revolution as you said does "being more agressive with the "fines ratio" mean that I can shorten the length and still have good attachment and low aero drag? As I said the plan is for a lakester so I will have expose wheels but my plan is to have them at least 20 inches away from the car and all of the axles and connections covered by wing section shape fairings. I also plan to have both the inside and outside wheel coverings on the front wheels be non rotating and on the rear the inside wheel cover would not rotate. Is this worth the effort?

I have attached, I think, a picture of the Nissan gravity racer which does have faired wheels but I would of course not have the wheel fairings, but is this what you are describing?

Blue, I really appericate all of your input, and you will find on this site we are all greatful for any kind of aero info from an expert. Trouble is that we will use you like a "rented mule" to keep getting your ideas!!

Rex

I think that .28 Cd on the Tropfenwagen already shows you're on to something with your wing as body lakester concept.

[PorkPie]

Blue, Just curious why then does all of Jack Costella's cars with their flat bottoms are so fast?  Is it because of the top shape? Or?

The flat bottom of the Costella creation is so low to the ground that it eliminante the airflow effect which Eric explained.
But this is only possible if you run without suspension and you use the frame for the necessary twist during the run.

By the way - Eric - can you explain me the word "blunt" - sorry, for this word my English is too short.

And  other thing - Al used a wing in August 2002 and slowed his speed down by 20 mph (5 percent).....using a wing, means to use the right shape...otherwise it works like a air brake

[maguromic]

"and you use the frame for the necessary twist during the run."

Can you explain this a little better? Does this mean that the frame is made to twist to take the load like a shock?

[RichFox]

NT3 has urathane blocks built into the frame structure to allow some give in the frame. I don't know abiut the others.

[PorkPie]

Jack used a very interested combination for the frame design.

some parts are built to Cremona - which means a very stiff (strong) frame design - in the other part he used a standard frame design - which is only half so stiff.

the result is, that this frame works like a shock absorber.......

in other words - when one of the wheels moved up...by rough salt....the whole bottom makes the same move and stays so parallel to the ground.....(the most of the time)

very strange....but not strange for Jack Costella Innovator.....

This frame design and the now possible low bottom is one of the secrets why - especially the NT II - his racers are so damn fast.

[Ratliff]

http://www.landracing.com/forum/index.php/topic,3999.0.html

In these photos of the Bruce Crower streamliner, it can be seen how Crower combined full suspension with side skirts.

[Dean Los Angeles]

Forget 81 mph. What if aero was unimportant?

How about 167 mph on a bicycle!


http://www.fredrompelberg.com/en/html/algemeen/fredrompelberg/record.asp

[Ratliff]

And the open motorcycle guys could use some of these tail section ideas:

http://www.speedbikebgl.de/eng/galeriee.htm

sadly the partial streamlining rules preclude the use of most if not all those tail sections , any further  benificial streamlining  is frowned upon for our own personal safety in the event of an unexpected sidewind,which may or may not  upset the apple cart  , brute horsepower has flirted for to long with marginal traction and is on a loosing bet , fiddling around the edges with frontal area is all thats left ,unless the rules regarding partial streamlining change ,sad but true 
[/quote]

http://www.motorcycleshows.com/motorcycleshows/data/articlestandard/motorcycleshows/342007/451724/HistoryofSpeed_300.gif

Checkout the tail section (above) on Joe Petrali's world record Harley.

Below is a good photo of one of the Moto Guzzi dustbin fairing bikes. According to the plaque I saw at a museum, these bikes would do 180 mph on 75 horsepower.

http://www.webbikeworld.com/Moto-Guzzi-motorcycles/guzzi-photos/oldGuzzi.jpg

[willieworld]

i think you guys are mistaken  jacks car is 23 feet long (salt snake)  any flex in the frame would allow the bottom to drag  not a good thing --i will see jack at el mirage this week end and will ask him and let you know   willie buchta

[thundair]

Blue
I am with you on the flat bottom and my reasoning is that I see the area around the streamliner that is closest to the ground is similar to a root section of a wing where it attaches to the fuselage. Imagine that being a sharp corner and the turbulence that would be created...

Could I tap your skills one more time as I am building a motorcycle streamliner and although I am in the gathering and design stage right now I would hope I am going in the right direction..I have two sheets of aluminum bent up like a taco shell and the plan is to make it look like a diamond looking from the front. The wing profile I was planning on is NLF-0414F although I now think that tangency with any profile will suffice.. What say you?/

Thanks in advance

[Ratliff]

"1. Absolute minimum separation: No blunt rear ends, minimal wheel openings, fairings in front and behind the tires.
2. Ground clearance:  "ground effects" may sound sexy, but they are high drag.  If we need downforce, we should use a low drag wing, high up in clean air like Teague did.
3. Absolute minimum wetted area:  They are SHORT!  Shorter means more aggressive pressure recovery, the first trade-off."?

Hmmm.

Line drawing of Frank Lockhart's Stutz Blackhawk.

200+ mph on three liters in 1927!

http://www.jalopyjournal.com/forum/attachment.php?attachmentid=288047&d=1174003168

Here's a link to great photos of Bob Rufi's car with and without wheel fairings.

http://www.jalopyjournal.com/forum/showthread.php?t=149631

The aft section of a streamliner Breedlove built for the wheel driven record, and later converted into a rocket car, had some similarities to Lockhart's car.

http://www.landracing.com/forum/index.php/topic,3900.15.html

The Pumpkin Seed was another example of a successful high ground clearance design.

http://69.10.163.89/PUMKINSEED.JPG

[aircap]

Just FYI - that Breedlove car Ratliff mentioned is in a private collection here in Wichita, KS.

[PorkPie]

i think you guys are mistaken  jacks car is 23 feet long (salt snake)  any flex in the frame would allow the bottom to drag  not a good thing --i will see jack at el mirage this week end and will ask him and let you know   willie buchta

Willie, this "flex" concept for the frame is only used for the II and III - both bikes - the Yellow Submarine and the Salt Snake (Cliff Gullett) got a frame built to Cremona - means very stiff. If Jack used this flex for the bikes the racer would be all over the place...but not straight going.

[Ratliff]

http://en.wikipedia.org/wiki/Reynolds_number

Explanation of Reynolds number

[Ratliff]

Rex: The flat bottom is the single worst feature after the LSR-typical blunt tail.  Far better would be to get rid of the corners (vortex generators) and round the lower surface up to meet the sides.  Get the whole thing up off the ground and fair the wheels.  A flat bottom will always be 100% turbulent and leads to a difficult aft closure with a greater potential for separation.

The 66012 is a good section for laminar run, the 60's torpedo data shows that we can be even more aggressive with bodies of revolution (like a lakester).  Remember, the 66xxx series were designed as wing sections.  Bodies of revolution can achieve much more aggressive fineness ratios and closure for the same degree of pressure recovery.

Blue, when you fair the wheels, you are no longer a lakester...
Don't lakester bodies need to be designed with the rotating open wheels considered?  And will the placement of those wheels effect the outcome?
And sorry, I like flat bottommed lakesters... 

http://www.mulsannescorner.com/diffuser.htm

Some further insight into flat bottom aerodynamics.