skyscooter
Well-Known Member
Last summer, my wife and I moved to a house that backs up to a large neighborhood pond. Since then I've enjoyed watching bird activity around the pond. We also put up a bird feeder in the back yard, which has attracted quite a few Mallard ducks who regularly stop by for a free meal. Watching these ducks land and takeoff from our back yard and from the pond, as well as flying around the area, has been particularly fascinating to me. It has been interesting to notice how fast that they need to fly; indicating a rather high wing loading. They also have a rather high "power loading" as they often fly in ground effect and zoom up just high enough to fly over the fence before dropping down close to the ground and pond. When they come in for a landing, they go into "high CLmax mode" plus a lot of flapping to slow down. Even then, they often still have forward momentum that tends to cause them to stumble forward and basically looking like controlled crashes. The Canada Geese don't try to land in our yard, but their takeoff and landings look similar to the ducks. At the other end of the spectrum, the occasional Blue Heron, with its much larger wing area and resulting lower wing loading, has a much more graceful and controlled takeoff and landing.
This afternoon I decided to plot the weight and wing loading for those three birds on the "great flight diagram" from Henk Tennekes' excellent book "The simple science of flight". The results are shown below. Being a logarithmic plot, it allows a great span of data to be plotted. There is a strong correlation across all kind of things that fly, from the Crane fly to the 747. Anything to the right of the line has a higher than average wing loading; with lower wing loadings to the left. The Canada goose, and to a certain extent the Mallard duck, are migratory birds and you would expect that they would be close to the trend line, or to the right of it. The plot shows that they are. Flying machines, whether birds or airplanes, to the right of the curve tend to have higher cruising speeds.
However, the plot shows the Blue Heron quite away from the trend line in the other direction. Apparently the Bird Designer decided that with its very long legs needed for wading in shallow water to feed, it needed the much lower than average wing loading that allows it to land in shallow water or along edge of the pond. The data points aren't labeled on the plot, but many of the points even further to the left than the Blue Heron are human powered and some low wing loading powered airplanes. Like the Heron and human powered airplanes, those far to the left of the curve are special application flying machines that have some special requirement driving it from the "average" flying machine represented by the trend line. A low stall speed requirement, such as for Light Sport or Ultralights, can also drive the points to the left of the trend line.
Anyway, it was a fun exercise for me to look at this today. I hope that the forum readers find it interesting too.
This afternoon I decided to plot the weight and wing loading for those three birds on the "great flight diagram" from Henk Tennekes' excellent book "The simple science of flight". The results are shown below. Being a logarithmic plot, it allows a great span of data to be plotted. There is a strong correlation across all kind of things that fly, from the Crane fly to the 747. Anything to the right of the line has a higher than average wing loading; with lower wing loadings to the left. The Canada goose, and to a certain extent the Mallard duck, are migratory birds and you would expect that they would be close to the trend line, or to the right of it. The plot shows that they are. Flying machines, whether birds or airplanes, to the right of the curve tend to have higher cruising speeds.
However, the plot shows the Blue Heron quite away from the trend line in the other direction. Apparently the Bird Designer decided that with its very long legs needed for wading in shallow water to feed, it needed the much lower than average wing loading that allows it to land in shallow water or along edge of the pond. The data points aren't labeled on the plot, but many of the points even further to the left than the Blue Heron are human powered and some low wing loading powered airplanes. Like the Heron and human powered airplanes, those far to the left of the curve are special application flying machines that have some special requirement driving it from the "average" flying machine represented by the trend line. A low stall speed requirement, such as for Light Sport or Ultralights, can also drive the points to the left of the trend line.
Anyway, it was a fun exercise for me to look at this today. I hope that the forum readers find it interesting too.
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