Learning from the Birds

Passerine Sparrow Jump Sequence

I have previously looked at how past human endeavour has inspired and shaped the design principles at Passerine Aircraft. In this post, I will have a look at the other major inspiration: nature.

Learning from nature is hardly new. Many aspects of engineering have been informed by studying the natural world. Today, with advanced materials and controllers, we are able to take this even further by creating machines capable of mimicking advanced motions and functions seen in nature. The development of devices which actively mimic something found in nature is called biomimicry, and it has resulted in some really incredible designs.

Biomimicry in robotics

Robotics is one of the best areas to see biomimicry in action. There have been several bio-inspired robots. Boston Dynamics has developed some of the better known examples, like the BigDog, which was designed for the U.S. Military to act as a robotic pack mule. Robots like BigDog, are not restricted by the environment in the same way that normal wheeled or tracked robots are. As designers search to further improve the mobility of robots in difficult to traverse terrains, they are again looking to nature for inspiration. One example of this is the SALTO robot (pictured below) that was developed at the University of California, Berkeley.

Exposed Electronics on Robot
The SALTO 1P (Thank you to Ethan Schaler for permission to use this picture)

This particular robot draws inspiration from the Galago or Bush Baby (pictured below) to create a jumping leg with significantly higher jumping agility than other jumping robots.

Jumping Galago
Taxidermy of a Bush Baby (Photo credit: Ryan SommaCC BY-SA 2.0)

Jumping agility is a measure of jumping height and the number of consecutively executable jumps. If the robot can jump very high but is only able to do one jump, it actually has low jumping agility. The same is true of a robot that can do a lot of small jumps quickly. What SALTO is able to do is a lot of large jumps quickly (so it has high jumping agility). The latest version of SALTO can do some really amazing manoeuvres. I recommend watching some of the videos of it in action.

The increased efficiency of SALTO was achievable because of new innovations in control technology that imitate nature better than ever before. With this in mind, what can we learn about flying from the natural world? The obvious creatures to examine for inspiration are birds.

Flying Naturally

Birds are truly masters of the air. They are able to traverse huge distances, yet they also exhibit incredible agility. One thing which stands out from observing them, in comparison to our aircraft, is that we can still improve our flight control technology a lot.

Another thing we notice is that very few birds hover; and those that do, tend to do it for as little time as possible. This is due the high amount of energy required for this mode of flight. From this we can draw a very similar lesson to what I concluded in the Lessons from The V/STOL Wheel of Misfortune blog post…

Don’t Hover.

Birds generally avoid this in two ways. Either they perch so they can drop and pick up speed, or they…

Green-backed Heron Taking-off
Green-backed Heron taking-off

Additionally, birds tend to avoid hovering when they land. Generally, a bird will slow down as much as possible (flare) and then use its legs to absorb any remaining velocity. This is a complicated manoeuvre which requires co-ordination between the different parts of the bird’s body. However, it does provide an extremely efficient (both in terms of time and energy) way of landing at the end of a flight.

Snowy Egret Landing
Photo credit: David Baron — CC BY-SA 2.0

Adding the Passerine to Aircraft

A Passerine is a type of bird (a perching bird), and at Passerine Aircraft we are adding some of the natural abilities of birds to our aircraft. With modern control systems we are now able to perform some of the fairly complicated manoeuvres done by birds, both at the start and end of a flight. This gives our aircraft the ability to take-off and land, both quickly and accurately, without a runway. Our aircraft are able to jump to take-off and can perform a flared landing just like a bird.

Jumper Legs on Test Craft