Nature's Flyers Tricks For Efficient Travel Over The Ocean
Nature's flyers (Birds, bats, and insects) have some tricks they use to travel over the ocean without using much energy. Some travel long distances over the ocean while hunting (sea birds) and others mostly for migrations. I am collecting some of the tricks nature's flyers use to save energy here with the idea that maybe drones could use some of these eventually.
1. Dynamic Soaring
By moving back and forth between two layers of air that are moving at different velocities an Albatross can soar for long distances over the ocean. The video below explains how it works.
This trick is a bit like sailboat. A sailboat has a sort of wing in the air and then a sort wing in the water (keel) and gets energy from air while the keel keeps it from being pushed downwind. An Albatross gets energy out of the air when it is up high and then pushes off the low air to keep from going downwind. The Albatross is very efficient in that it uses the same wings for both jobs. Like a sailboat it can not soar directly into the wind but can go upwind at some angle.
Drones can be of similar size to an Albatross and this can be done very low over the ocean (say 0 to 20 meters) so this
seems to have real potential for drones. There are RC gliders that have flown record speeds using this trick with high speed wind near the top of a
hill and lower speed air nearby.
If a solar airplane could just use this trick to stay in the air overnight it could let a solar airplane go around the world. Of course if it could do this overnight it could do it during the day and so not really need the solar. But maybe solar can give you better speed toward your destination during the day.
The Albatross ranges well South or well North, not near the equator. This is because the winds and wave swells needed for this trick are not near the equator. As we live in tropical Anguilla, we don't normally have good conditions for experimenting with this trick. We might be able to try it when a tropical storm or hurricane is nearby.
2. Wave Slope Soaring
Waves close to shore, just before breaking, can lift up air fast enough that Brown Pelicans can soar.
3. Annual Migration Downwind Both Ways
The Pantala flavescens dragonfly migrates thousands of km between Asia and Africa each year. It uses the seasonal winds so that it is going downwind both ways.
4. Small Birds Ocean Migration
There is a weather formation where a two different air masses are touching that makes a lift zone. If one of these is crossing an ocean, then birds can use it to soar for hundreds of miles.
This is at heights of airplanes and with clouds for reduced visibility so probably not going to be a good trick for drones to use.
5 No slope soaring or thermals like on land
The ocean does not have big hills to turn wind upward for slope soaring, or places that get hot for thermal soaring. So these two land tricks don't work for ocean travel, but seem worth noting.