Every time I've flown a long haul flight I've noticed winglets on my aircraft, be it Airbus A340, B-747, B-767, etc. But the B-747D version is a short range model of the 747 that lacks winglets. Do winglets on commercial aircraft somehow make them capable of long haul flights? If so, why?
Winglets have the effect of greatly reducing drag, which allows for greater fuel economy, which does aid long-haul flights. However I am suprised that any civilian aircraft do not have them - fuel economy is a good thing even in short-haul flights.
Winglets (Whitcomb* winglets) have the effect of making the span effectively infinite - yes it seems silly that putting a definite "end" on a wing makes it act as if if it were longer. The way it does this is that the winglet prevents high pressure air flowing round the wing tip into the low-pressure zone above the wing, this increases lift by reducing losses and also reduces drag. http://oea.larc.nasa.gov/PAIS/Concept2R ... glets.html * Named after Richard Whitcomb, the guy who also came up with area-ruling for supersonic aircraft. Just found out that Lanchester also made this discovery...
The 747 you are speaking of (I've heard of the 747-300,but not a D version,where did you come across this info) isn't so much short range as it is high capacity.It's used to move a lot of passengers over distances that are too short (also I believe,not enough altitude) for winglets to be effective.BTW,this version of the 747 is illegal to use in the U.S.
Ooops!I'm a bit rusty on my commercial aircraft.The plane we are referring to is the 747-400 D.The D stands for domestic.The -400D is widely used in Japan.Other than that I'm not sure.