Aerodynamics

[k.h.]

I don't have info on that particular test criteria, but suspect it was not spinning.  As the dimples are turbulators, creating turbulance in the boundary layer.  Laminar flow has less drag, but it is more prone to separation and drag rises because of eddies that form in the gap. Turbulent flow has more drag initially but also better adhesion, and therefore is less prone to separation. If the shape of an object is such that separation occurs easily, it may be better to turbulate the boundary layer at the slight cost of increased drag.

On the premiss that a shark "glides" 20 percent faster than most other fish, we worked on sharkskin for awhile.  1st problem being it tests best in a water tunnel.  2nd problem being we received an email within the last month from a researcher who filed a provisional patent on the geometry of sharkskin giving us a heads up to discourage further investigation.  Seems the future use is to cut fuel consumption on ships, but there is some work being done in imitation sharkskin in Germany; the technical hurdle is how to apply it and will it keep organisms from fouling the surface.  Dried sharkskin makes a better sandpaper than drag reducing medium.

[wobblywalrus]

Racer X, a modified frame is a good idea for a person who is serious about aero.  The chassis needs to have all wide parts at about the same height.  In other words, the wide part of the fairing ahead of the head, shoulders, and hands should be about the same height as the broadest  section of the tail behind one's boodie.  Also, the wheelbase should have ample distance to allow streamlining with a non-truncated teardrop shape.  None of the standard street bike chassis I have seen provide this.

[racer x]

That is my next BIG modification. I need to extend the rear wheel so I can make a better rear fairing . and still Keep it 3 inch behind the tire. As it is now I am sitting on the rear tire. The extended swing arm will allow me to hide the nitrous bottle in front of the tire keeping out of the slipstream.

[RichFox]

Please observe small red car in picture to the left. What's this about Aerodynamics?

Which red car?

This red car

[Stan Back]

How would you describe that color?  --  Brick red?

Stan

[4-barrel Mike]

I don't think that it's "resale red"   

Mike

[akk]

There are some really good aero books out there. My favorite is:

Fluid Dynamic Drag by Hoerner 1965...This guy did a lot of aero work designing the Me109 for the otherside and after the war for Lockheed. The book is full of wind tunnel data all explained with equations...you can ignore the math and with reasoning learn from the graphs ....the car stuff is really old but informative...The section on interference drag is priceless. I feel that interference drag is the dirty little secret that modern CFD and fancy computer programs don't handle well. The section on transonic speeds should quiet fools that think 1000 mph with a tire driven car is possable...(as long as tire driven is traction and not salt shredding pikes or something).

I have other books I like. Please add to my book review or describe your source of wisdom?

Akk

[SPARKY]

off to Amazon 

[racer x]

Shape and Flow. The fluid dynamics of drag by Ascher H Shapero.. 

[Captthundarr]

The red car to the left has the aerodynamics of a bale of hay but who cares it's kool . What is it that guy says "given enough velocity even pigs can fly"

[F104A]

Here is an image of the NAE and the pressure against the wheels and the shock wave generated at locations around the fuselage.
This is using Ensight and CFD++ software. This is of course with no fairings installed at this time.

[jl222]

 
 I have a foto of Thrust breaking the sound barrier from above, the dust cloud [shock wave] goes straight out at right anglels from the sides from front of streamliner for a great distance.
 Do any of the CFD programs show the same results?

               JL222

                           

[WOODY@DDLLC]

CFD shows the whole cone formed by the shock wave or at the surface.
(Pix from Thrust & Bloodhound sites.)

[Blue]

There are some really good aero books out there. My favorite is:

Fluid Dynamic Drag by Hoerner 1965...This guy did a lot of aero work designing the Me109 for the otherside and after the war for Lockheed.

I have other books I like. Please add to my book review or describe your source of wisdom?

First published in 1951 and updated in 1965, it has never been superseded.

Best book on aircraft design: "Aircraft Design: a Conceptual Approach", Dan Raymer.  Lots of tables, illustrations, and examples so you don't get lost in the math.

Best drag book (after Hoerner): "Personal Aircraft Drag Reduction", Bruce Carmichael.  Private publication, out of print, try some air show booksellers for a used copy.

Best car aero book: "Race Car Aerodynamics", Joesef Katz.  More focused on design for downforce, it does blow up a lot of myths that non-aero car racers have about car aero.  It also illustrates separation vortexes behind common configurations.  I'm hoping for an update in a year or so now that Indy and LeMans cars have gone to low-separation tails to make up for radical HP reductions from 2011 to 2012.

Best pure wing book: "Theory of Wing Sections", Abbott and Von Deonhoff.  THE definitive collection of air foil and wing data from wind tunnel testing done by NACA, post war.

There is currently no good reference on the details of interference drag and how to cure it.  I do this for a living, and most of the information available besides the experimental evidence of one design being worse than another is simply wrong.  For a modern look at how we reduce interference, look at the fuselage and nacelle interfaces of late model business jets, and the wing-fuselage-engine pylon interfaces of the 787, 747-8, and 737NG.  This is an area where Boeing has a significant edge over Airbus.

[SPARKY]

Off to the Scottsdale Airport