NYTimes Aero Article - Edgy, Yet Still Aerodynamic

[NachtRitter]

Originally Posted by fanamingo

It was meant as a joke. The CFL is intended to provide light for windtunnel crews studying an otherwise "black art".

Aaaaaaah... I get it!! (duh!)

[cfg83]

fanamingo -

Originally Posted by fanamingo

It was meant as a joke. The CFL is intended to provide light for windtunnel crews studying an otherwise "black art".

I thought the "joke" was that the light bulb was very close to the shape of a tear-drop and could be used to demonstrate really good aerodynamics.

*shrug*

CarloSW2

[NachtRitter]

Originally Posted by cfg83

I thought the "joke" was that the light bulb was very close to the shape of a tear-drop and could be used to demonstrate really good aerodynamics.

Ya, that's why I didn't get it originally either... an incandescent is shaped aerodynamically, but a CFL is usually shaped like a coil of glass tubes... which doesn't seem to be all that aero... (granted, there are some CFLs that are bulb shaped, but those are less common)

[basjoos]

Originally Posted by instarx

The danger of wingtip vorteces from landing aircraft wan't fully realized until the 70's or 80's.

The air force became aware of this in the 50's once they started messing with large, heavily wing loaded jets. (notably the YB-70/F-104 accident). It didn't start becoming important in civilian aviation until the introduction of the Boeing 747 and other "heavies" into the airport environment, where the mix of smaller, lightly wing loaded aircraft and large heavy wing loaded "jumbos" created a safety problem that had to be studied and regulated.

Originally Posted by instarx

Why all the resistance to a few new novel ideas being applied to aero in cars. Doesn't every little bit help? Maybe everyone got up on the wrong side of the bed this morning?

I don't have any resistance to these ideas. I was just pointing out that they are merely aerodynamic tricks to try to clean up an otherwise inefficient aerodynamic design (sort of like adding stall fences to an aircraft's wings to correct an aerodynamic deficiency) and that by themselves they won't turn the typical 0.36 Cd car into a 0.22 Cd wonder.

[Otto]

The "area rule" or Coke bottle fuselage was known in the 1940's, and to my understanding was first used in the Grumman F8 Bearcat, a high performance propeller aircraft that was a composite of the best ideas then available, taken from German, Japanese, and Allied aircraft and rolled into one new plane. Unfortunately, the Bearcat came at the end of the war, and propeller designs were dumped as the new jets came in. Area rule showed up in the F-106 et al in the 1950s. See also B-58, T-38, etc..

[SuperTrooper]

GM has had great aero designs dating back to the '50s! But no, they wouldn't build them. No wonder they are in trouble.

[SVOboy]

Damn, I wanted to post this! Nice job.

[basjoos]

I’m afraid this is just another example of automotive stylists gone wild rather than an honest attempt to create a low Cd car. This was GM’s turbine powered concept car, the 1959 Firebird III, so they were styling it to resemble a jet fighter. Since they were copying a very low Cd subject (a jet aircraft), they couldn’t help but to get some of the aerodynamics right if they were to retain the “look” of a jet fighter. But there are a number of aerodynamic flaws. Most noticeably, the angle of the trailing edge of the canopies is far too sharp to retain attached airflow. The fins are mostly for show. The vertical fins would provide some yaw stabilization, but the 4 horizontal fins are totally useless (no need for roll control on a ground vehicle), unless they are using them to generate downforce. There is also a big ridge along each side of the hood that is drag inducing and is there purely for cosmetics. Also the stagnation point on the nose is too high for a ground vehicle. Its certainly neat and cool looking, but not low drag, except purely by accident.

However the 1980 GM Epcot 2003 is a different story, now that was a concept car designed for low drag. And, of course, the 1988 GM Sunraycer.

[TestDrive]

Originally Posted by basjoos

However the 1980 GM Epcot 2003 is a different story, now that was a concept car designed for low drag. And, of course, the 1988 GM Sunraycer.

1980 GM Epcot 2003

1988 GM Sunraycer

[aerohead]

Originally Posted by instarx

If aerodynamics has been fully understood since 1800 why all the discussion of dimples, air tabs, ziggy tape, etc in ecomodder? For decades aircraft designers "knew" that there was nothing better than a teardrop shape for a fuselage, but then in the 1980's it was discovered that constricting the fuselage in the wing area was a much more efficient shape. Even the effect of dimples on golf balls wasn't discovered until 1850ish. Winglets on the end of wings to improve economy are a recent discovery. The danger of wingtip vorteces from landing aircraft wan't fully realized until the 70's or 80's. So it seems kind of silly to claim that aerodynamics has been fully understood since 1800.

Why all the resistance to a few new novel ideas being applied to aero in cars. Doesn't every little bit help? Maybe everyone got up on the wrong side of the bed this morning?

instarx,your questions are good ones.My short answer,at least for the United States (and this is an observation and not meant to be a mean-spirited comment),is that there is no public education with respect to the physics of automobiles.( That's why we are attempting to do it here ).------------------

With respect to my comment about 1800,I should have qualified the comment,and limited it to aerodynamics as applied to automobiles,which did not yet exist at the time.------------------------

Your remark about contraction of the fuselage is in the realm of aerospace engineering,and derives from Dr.Whitcombs research in supersonic flight."Whitcomb-waisting" or "Coke-Bottleing" is found to provide for "high sectional- density",with a constant cross-section along the longitudinal axis of the aircraft, where the wings interface with the fuselage, providing for more uniform pressure distributions along that axis.This is not something which really concerns us as aero-modders.------------------------------

The dimpling phenomena does not affect our investigations either,do to Reynolds Number effects,although does solve D'Alemberts Paradox,as at the time of his fluid dynamics research,the concept of viscosity and shear did not exist.That would have to wait for Prandtl.--------------------------

Wing-tip vortices also have no bearing on ground vehicle aerodynamics,and today,as no doubt tip-vortices are addressed for economy among aircraft,their primary function is to compress landing intervals between arriving planes.--------------------------------

So,in order to keep the pot stirring,I'm going to hold to my claim that the year 1800 probably signaled the date for a general understanding of fluids as applied to automobiles,and todays University' 7,000-mpg vehicles,are direct descendents of Sir George Cayley's trout.----------------------

Any corporate spokesperson who genuinely believes that aerodynamics is a "black art" has never looked at the sky or seen things swimming below the water.