ALBATROSSES ‘CHEAT’. MUCH OF THEIR PROPULSION COMES FROM THEIR ABILITY TO RIDE THE WIND AND WAVES.
the same ‘runway’, unable to cope with landing nearby, and I’ve also watched becalmed albatrosses paddling around in the Southern Ocean like big ducks waiting to be thrown bread. Albatrosses are hardly all-rounders.
The albatross wing-shape and flight style are, moreover, comparatively simple. The wings are long, narrow and pointed, a shape described as a high aspect ratio (aspect ratio is the ratio of wing length to width). They are also held out rigid – indeed albatrosses have specially modified joints that ‘lock’ them in position. Long wings are good for lift, too (the lift force produced by the aerofoil shape adds up all along their length), and narrow wings are great at reducing drag.
CREATURES OF HABITAT
Drag is the force that counteracts forward propulsion, and it comes in two main forms. Forward movement generates friction against the air, but very narrow wings will naturally generate less friction than broad ones. At the same time, the movement of wings through air creates turbulence and eddies, which add to the drag – but, once again, narrow wings reduce this. Such a wing shape is perfect in uncluttered places, including the open ocean, where manoeuvrability is not a prime concern.
Albatrosses also ‘cheat’. Much of their propulsion is not self-generated, but comes from their ability to ride the wind and waves and harness their power. They do this in two ways: first, they allow updrafts hitting the tops of waves to hoist them up (a wind speed of 10m/s is theoretically able to lift them to 20m), so that they can glide down. And second, they glide upwards into headwinds, gaining energy purely from variation in horizontal wind strength over the ocean.
So albatrosses travel effortlessly, yet without strong winds they are pretty helpless. They are very much creatures of habitat. Does that really make them great flyers?