Tag Archives: aerodynamic

Wingtip Treatments

Richard Whitcomb was an aerodynamicist at NASA who pioneered a number of technologies that benefit the aviation world today.  One of those was his development of winglets.  These are the wingtip treatments that improve lift to drag ratio and climb performance without significantly extending the wing.  While his work was clear, it took a while for them to be implemented widely.  Now, most aircraft involve some sort of wingtip extension.  However, the first aircraft to replicate his design approach was the MD-11.

The MD-11 had a split winglet with a larger extension upwards and a smaller one downwards.  This reflected some of Whitcomb’s original drawings.  Strangely, after this, the focus was on upward winglets only (although the Airbus approach for a while was what they called a fence on the wingtip which was something more in keeping with the Whitcomb approach).  Recently, there has been a return to the original with APB introducing the Split Scimitar and Boeing producing their own Split Winglet design (not as elegant as the APB approach in my mind.

Most airliners and many business jets now incorporate a tweaked wing tip configuration.  Maximizing the aerodynamic performance requires squeezing as much as you can out of the design within the space constraints you have.  The following pictures are examples of the different types used.

What Does 40 Years of Design Get You?

AU0E1641.jpgThe Boeing 747-8 has not been a terribly successful program.  Boeing decided to update the 747 family with new engines and revisions to the wing along with a stretch to the fuselage.  The resulting jet was delayed by its own and other program issues and it came around at a time when there were few passenger airlines interested and the freighter market was taking a kicking.  The result has been anemic sales and a production rate that has steadily reduced as a result of the low demand.  However, from a technical point of view, it is a nice upgrade.

C59F2632.jpgThe wing came in for a lot of attention and was significantly redesigned.  The most conspicuous change is the introduction of the swept tips common to many Boeing designs these days.  Less obvious is that the flap system was completely redesigned.  The original 747 flaps, carried through on the 747-400 are very complex.  Sections are triple slotted.  The Boeing aerodynamicists came up with a single slot design to replace this which apparently has good performance but I imagine is a lot simpler to make and maintain.  Only from the rear on approach can you see the difference.  These shots compare a 747-400 from Air New Zealand with a Korean Air 747-8 and you can see for yourself how much simpler the new design is.

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Aerodynamic Specialties

AU0E3770.jpgThese days you will struggle to come across a car that has not undergone extensive aerodynamic optimization. Even those cars that look like they have deliberately avoided an aerodynamically efficient shape will actually have undergone considerable testing to make sure that they are not just relatively low in drag but that they are also stable at speed. The widespread appreciation of aerodynamic performance became apparent in the 80s with the introduction of various cars that had noticeably lower drag than their competitors and associated improvements in fuel consumption.

AU0E3767.jpgHowever, the 80s was not the first time that aerodynamics occupied car designers. Go back a long way and you will see some very interesting shapes on cars. Some of these were looking to emulate the space age looks that were popular at the time. Others were real attempts to reduce drag. Blackhawk has a collection of three Alfa Romeo models. These show the iteration of design to try and achieve very low drag. They don’t look anything like a modern car and have more of a Jetsons appearance. However, they are a fascinating look at how some car designers were thinking at the time.

AU0E3755.jpgObviously modern cars don’t resemble these machines which suggests their approach was not the best way to go. They also look like they would have been expensive to manufacture. What they do show is the willingness to push the envelope. It is great that they are still around for us to check out and see what was seen as cutting edge at the time.