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Who does it better? Bird Flight vs Human Flight

September 30, 2019 No Comments


In this video, we’re going to look at a
few different types of bird and a few different types of aircraft all with the goal of answering
the question “Who does it better? Bird flight vs Human Flight”. Let’s get to it. There are a few problems, or difficulties,
when comparing different aircraft together. The first is that aircraft are very mission
dependent. This means it is designed to perform a specific
task or a set of tasks that are closely related to each other. And so, it’s hard to adapt an aircraft to
a different set of requirements or a different mission that is very different from its original. For instance, if I showed you a picture here
of a small lightweight Cessna and a SR-71 Blackbird and asked you which one was better
for crop-dusting the obvious answer is going to be the aircraft on the left. The small Cessna is going to be better for
that new task or that new mission. Now this is a problem when we’re trying
to compare different aircraft or even aircraft to birds. Instead of looking at aircraft and trying
to find the best aircraft and comparing it to the best bird, what we’re going to do
is generalize it and look at different parameters of different aircraft as sort of capabilities
of general bird flight or general human flight. And we’re actually going to go ahead and
leave rockets out of this. Rockets and rocket planes generally produce
most of their lift from their huge engine in the vehicle. I’m not wanting to go that direction in
this video so we’re going to go ahead and stick with aircraft that are generating most
of their lift with their wings. So general aircraft. There’s another problem when trying to compare
aircraft and that is the size difference. To try and explain what is meant by this I
have a question for you. If I have a wing design, right a wing shape,
if I double the size of that wing, and because of that it produces twice as much lift, does
that mean that the design is twice as good? And if I wanted to compare it to a different
aircraft wing design, how am I going to know which is the better design if all I need to
do is just double it to get more lift? This is the reason that in aerospace engineering
we often normalize the parameter that we are looking at by a common value, a common parameter,
so that we can better assess what is a better design. For instance, if I wanted to compare the lift
and drag that a wing produces to find out which is the better designed wing the lift
will actually be normalized by the planform area thereby creating a standard by which
I can measure either the same wing or a different wing at a different size. For instance, if I normalized my wing by the
planform area then the lift would double if I doubled the planform area. However, the coefficient of lift, right the
normalized lift, would not double. It would remain the same. And so, what we can do is we can compare this
normalized lift, right the coefficient of lift, of this wing I have over here versus
a different wing, and we can assess what is the better design. And so, when we’re trying to compare bird
flight and human flight in this video we’re going to go ahead and do something similar. We’re going to try and normalize the different
flight parameters so that we’re comparing the different designs and taking out some
of the effects of the scaling issues that arise due to the difference in size of most
birds and most aircraft. Let’s go ahead and look at the first flight
parameter which is how high can we fly. Now when looking at how high we can fly let’s
go ahead and just choose the height of the bird versus the height of the human to normalize
and compare the two against each other. So, if we look at the highest an aircraft
has flown, we have a record flight of 123,520 feet back in 1977 from a MiG-25. If we take this record height of the flight
and divide that by the height of the aircraft or the height of let’s just say a person
of 6 feet, you’ll see that in a MiG-25 humans can obtain more or less 20,000 to 21,000 times
our height. However, if you look at a mallard duck, they
have been observed flying at 21,000 feet. If you take as an average height 10 inches,
you’ll see that it can obtain up to 25,000 times its height. So, when we normalized based on height, we
can actually find birds that can fly higher than we can in aircraft. Now the duck isn’t the bird that can fly
the highest. That actually goes to the Ruppell’s Griffon
Vulture. This thing has been observed flying at 37,000
feet. That’s up there where commercial airliners
fly. That’s crazy! That’s really high up there. Alright, lets go ahead and look at how fast
we can fly. The record airspeed for an aircraft was the
SR-71 Blackbird travelling at 2,193 mph back in 1976. That’s up there about Mach 3-ish. If you divide that by the aircraft length
of 107 feet, you’ll see that when we hop into an SR-71 Blackbird we’re able to obtain
about 30 body lengths per second. However, if you look at a common pigeon, which
is able to obtain a flight of 22.4 meters per second, they’re able to get, based on
their average length, about 75 body lengths per second. Just your common pigeon. Now let’s look at some of the “high performance”
birds. You’ve got your European Starling. That can get up to about 120 body lengths
per second. That’s 4 times as fast as a SR-71 Blackbird
if you scale it back to their size. That pretty impressive. Now I’ve got to give an honorable mention
as well to another flying animal. It’s not quite a bird but maybe we’ll
have another video talking about bat flight. The Brazilian Free-Tailed Bat is now the record
holder in terms of observed flying animals. It has been observed flying at 99.5 mph. Now you have to remember this is sustained
flight. There are other birds who might obtain a faster
flight but that is usually in some sort of dive. And so, this Brazilian bat was able to, based
on its average total length, achieve approximately 473 body lengths per second! Next time that you’re watching football,
or soccer, or baseball just imagine how different those sports would be if humans could travel
473 body lengths per second. And go ahead and drop a comment below if you
want to see some videos on bats and bat flight in future videos. If we try and look at maneuverability in terms
of roll rate, you’ll see that a highly maneuverable aircraft, the A-4 Skyhawk, was able to get
720 degrees per second while the barn swallow is able to get 5,000 degrees per second. Which is astronomical! I didn’t feel the need to normalize these
because both have to go through 360 for 1 full revolution. And so, I don’t normalize these but as you
can see, just looking at the total values here, the birds win this one. We don’t just have to look at flight performance
values. We can also look at G-loading as if we were
trying to see, structurally, how much maneuvering or how much loading can the different aircraft
or different birds handle. For general aviation we usually see a value
of 4-5 G’s. With military that can go up to 8-10 G’s. However, it has been estimated that some peregrine
falcons, when they do a nose-over entering into a dive, can see up to 15 G’s. So not only do they have a pretty amazing
structure that is able to withstand high loading they’re also able to stay conscious without
needing any of the tricks that do like pressure suits. So, let’s go ahead and look at endurance. And I will admit, this was the one that surprised
me the most in doing the research for and the creation of this video. Endurance is how long can you stay in the
air. It’s not about distance it’s about time. Recently within the past year or two, the
Airbus Zephyr (a solar powered unmanned vehicle) was able to set a new record for endurance
at 25 days 23 hours and 57 minutes, just shy of 26 days. Scientists have also discovered that the Common
Swift can be in flight without landing for up to 10 months! This value is actually obtained via experiment. They attached sensors to these birds, let
it fly around and do it’s thing, come home, and then they got the sensors and looked at
the data. Now you might ask “how in the world does
that bird stay in the air for 10 months at a time? Doesn’t it ever get tired or hungry?” Well, these birds actually eat in the air
and they sleep in the air. Let’s go ahead and look at range. Range is a distance thing. How far can you go before you land? This record was set recently in 2006 where
the pilot was able to travel 41,400 km before landing. If you divide that by the average height of
6 foot that gives about 22.7 million body lengths. If you divide that by the aircraft length,
it’s going to be a lot less than that. And if you look at hummingbirds, it is believed
that hummingbirds can fly up to 1,370 miles without landing. However, when you take into account that their
average body length is 3 inches that gives you a value of 28.9 million body lengths before
it actually has to touch down and land. Pretty crazy if you ask me. So, what is the conclusion from this short
fun video on bird flight vs human flight? Well, we see that when you take size into
account birds can fly higher, faster, farther, longer, quicker, and maneuver a lot better
than we can in our own aircraft. That’s probably part of the reason why McMasters
and Henderson said, “Humans fly commercially or recreationally but animals fly professionally.” As an aerospace engineer, it might be beneficial
to look at birds and see how they’re able to do this thing that we call flight, how
they’re able to do it so, and see if maybe we can’t start closing the gap between bird
flight and human flight. Now I spent a few hours researching this subject
and creating this video. So, if you liked it return the favor. Give me a like, give me a comment, or more
importantly subscribe to the channel.

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