The Common Murre!

October 2, 2011 at 12:49 pm

Yet another animal who can’t decide between the water and the sky, the Common Murre is a part of the Alcide family which contains two main species of birds (Common Murre and Thick Billed Murre). This penguin-like flyer lives in the cooler northern regions of both the Pacific and Atlantic oceans, although the Atlantic population is significantly larger.

Murres in their nesting grounds:

Also known as the guillemot in Britain, these birds use the ocean as a main source of food and live out the majority of their life on the water. In fact, the only time the Murre voluntarily lands is to participate in its annual nesting ritual.

When nesting, the birds gather in large colonies and take turns caring for eggs and gathering food from the ocean, until the eggs hatch. Then, after a few weeks, the male parent takes the hatchlings out onto the water as they learn how to hunt for squid, crustaceans and small fish.

These birds, which are awkward flyers, are fairly graceful underwater. Their rounded bodies can reach a length of 43 cm and they have a wingspan between 64 and 71 cm. To dive, the Murre lands on the water and flicks its wings backwards, and then bends its carpus (similar to a human wrist) to create an aerodynamic shape underwater.

The Murres ability to dive more than 150 ft and fly at speeds of 50 mph is incredible. They can taxi off of the water and have adapted their wing geometry to fit in multiple habitats, allowing them to be one of the more versatile birds of the ocean.

Murres Diving:

A Colony of Murres utilizing their underwater flying abilities:

References:

By Morgan | Posted in student post | Tagged | Comments (1)

A Robot that Flies like a Bird

September 26, 2011 at 2:08 am

For centuries, man has been possessed by the desire to fly. Naturally, nearly every inventor drew inspiration from the flight of birds. Nearly all of the earliest designs for flying machines attempt to replicate a bird's flapping wings. Unfortunately, replicating a bird's flight is exceedingly more difficult than one might anticipate. In fact, the motion is so sophisticated that no one has been able to construct a prototype that mimicks the complex motion until recently.

In July 2011, over 100 years after the Wright Brothers achieved manned flight, Markus Fisher introduced the world to his "robot that flies like a bird." To fully appreciate his presentation, it is important to understand the primary differences between fixed winged flight the type of flight he has succeeded in replicating.

The primary difference between the two styles of flying is that fixed winged flight (like that of an airplane) segregates lift and propulsion into two separate actions while flapping wings combine them into one motion. As we already studied in class, a fixed wing generates lift due to the forces of the air on the underside of the wing. When a wing is angled (i.e., is positioned with an angle of attack) the leading edge of the wing pushes the air forward and down. Due to the greater amount of force placed on the bottom of the wing, the air forces it to rise up as expected based on Newton's third law of motion. The force of the wing being pushed up causes the air on the top of the wing to increase in speed as it passes over. As the air molecules begin to move in the same direction (over the top of the wing) they no longer exert as much force down on the wing. In other words, they create a low pressure zone which enables the wing to lift upwards.

While the explanation for fixed winged flight seems complex, it is surprisingly simple in comparison to the method birds use to fly. Birds combine the already difficult concept of lift with propulsion. They do the two simultaneously. Biological wings can change shape and velocity as they flap. They slow down and stop at the end of downstrokes and upstrokes then accelerate into the next halfstroke. The wing base is always moving slower than the wing tip meaning that velocity increases from the base of the wing to the tip.

In addition, birds have the option of either using continuous-vortex gait (fast flight) or vortex-ring gait (slow flight.) Continuous-vortex gait produces lift during both the upward and the downward strokes of the wing. The downstroke produces a positive upward force and forward thrust while the upstroke produces a positive upward force and rearward thrust. In vortex-ring gait, the upward flap is passive and produces no thrust or lift.

As we take the time to study flapping wings, it becomes apparent that the motions birds use to fly is incredibly more complicated that what we have used in the past. It is also ironic, that it was the first form of flight modeled, and yet continuos to be the most difficult to replicate. With all the information in mind about how birds use their flapping wings to fly, perhaps we can better appreciate the sophistication and brilliance behind Markus Fisher's robot.

Sources:

"Aerodynamics." Department of Zoology. 26 Sept. 2011.

"Bird Flight." People - Eastern Kentucky University. 26 Sept. 2011.

By Charlie Schumacher | Posted in student post | Tagged , | Comments (1)

The Flying Mobula Ray

September 26, 2011 at 12:15 am

When it comes to sea dwelling animals, many people picture these creatures submerged in water all of the time.  However, could it be possible for them to fly? In the case of the Mobula Ray, the answer is yes.  This 17 foot long flat bodied ray, weighing over a ton, has the ability to launch itself out of the ocean.  This makes them the second largest species of manta ray, and despite this immense size, they can jump as high as six and a half feet out of the water.

Mobula-Ray

These talented creatures are found mainly off the Mexico’s eastern shore in the Sea of Cortez, and are one of four species of manta ray occupying the area.  The one question that remains: Why do these animals leap out of the water in such incredible fashion?

Some ideas that may answer this question have been proposed.  It could be a method of detaching parasite-cleaning remoras from their backside, a form of co-operative hunting, a way of tricking their prey to obtain easy food, or even just a form of play.  Despite extensive research, this remains a mystery.

flying-mobula_tmb

What we do know is that this behavior has proven to be dangerous.  One afternoon, a woman in Florida was killed when a ray leaped into the boat she was on, and struck her.  Due to its immense size, this type of incident will almost always prove to be fatal.  Thus, those who choose to share their fascination through spectacular pictures and videos posted on the internet must do so at their own risk!

Source:

By Nathan Provencher | Posted in student post | Tagged , | Comments (1)

The Physics of Wingsuits

September 25, 2011 at 6:32 pm

The amazing thing about the flight of animals is the seemingly simple nature yet unbelievable complexity of their evolved structures.  You would think that to mimic a flying squirrel would be easy, right? You know, just slap on a pair of wings and jump off of something. It couldn’t be that difficult.

Wrong.

It has taken almost a full century for skydivers and base jumpers to perfect the art of creating and using the wingsuit.

It all began in 1912 when Austrian tailor and inventor Franz Reighelt made a parachute jacket. Yes, a parachute jacket. It appeared just as any other jacket would, with a few extra bits and pieces here and there. Unlike the parachutes of his day, this one weighed only about 9 kilos (20 lbs).

After multiple tests on dummies off of balconies and buildings, he received clearance to test a dummy off of the first floor of the Eifel Tower. In a state of confidence, because of the press and many spectators at the event, Reighelt decided to test it himself. His equipment malfunctioned and he suffered a fatal fall, but his ideas prevailed.

Franz Reighelt

Franz Reighelt modeling his parachute jacket in 1912

Modern Wingsuits

Since 1912, the world of wingsuits has made leaps and bounds (quite literally). It has come to the point where the science of flight is being properly understood and manipulated accordingly.

Using the equation for terminal velocity (the point in which drag force=gravitational force), these adrenaline junkies have learned to manipulate their speed as well as control.

Terminal Velocity

This is where v=terminal velocity, mg=weight, C=drag coefficient, ρ=air density, and A=surface area

Simply put, a skydiver can adjust the surface area of his body that is perpendicular to his velocity vector and change his speed drastically.

Using the aerodynamic force of drag they can also control their flight direction and distance. With the proper body position most wingsuits can help a pilot achieve a 2:1 glide ratio-the exact ratio of the Northern Flying Squirrel (Glaucomys Sabrinus) according to the Journal of Mammalogy.

Below is a video that demonstrates some of the maneuvers possible with a wing suit.

It is clear that through changing the positions of ones shoulders and head affect the angle of attack and thus the flight path. The current world record for furthest distance covered in a wingsuit is an unbelievable 14.35 miles done by Shinichi Ito in 2011.

Resources:

Cordia, Jarno, and Steve Bartels. "Fallrate vs Glide Ratio." Team Fly Like Brick - Wingsuit Flight, Coaching and Instruction.

"February 4 | Franz Reichelt." Web log post. A Death a Day. 4 Feb. 2008.

"- Explore Records - Guinness World Records." Guinness World Records - Home of the Longest, Shortest, Fastest, Tallest Facts and Feats.

By David Villari | Posted in student post | Tagged , | Comments (3)

Gliding Vine Seeds

September 25, 2011 at 5:13 pm

Alsomitra macrocarpa, known as the Alsomitra vine or the Javan cucumber is “a type of climbing gourd.”

The vine is found mainly in the forests of Java, Indonesia.  Where it grows truly remarkable seeds by the hundreds in “football-sized pods.”

What makes these seeds so remarkable is the fact that they are virtually aerodynamically perfect gliders.  Each seed has a set of "paper-thin" wings that can support the seeds minimal weight with the slightest breeze.  The wings allow the seeds to travel hundreds of meters through the forest and once the seed lands, the wings rot away.

This remarkable evolutionary adaptation allow the seeds to disperse all throughout the Indonesian forest.  Each seed now has a greater chance to develop into a fully grown vine because they aren't competing with other vines for nutrients and sunlight.

The excellent aerodynamic properties of these seeds invoked two Japanese engineers, Akira Azuma and Yoshinori Okuno, to study the plant over 20 years ago.

The engineers discovered that the seeds glided with an angle of 12 degrees.  This means that the seeds fall only 0.4 meters per second.  These seeds truly have the best aerodynamic capabilities of any winged seed.

Decades before the two Japanese engineers calculated these figures, the excellent aerodynamic properties of the seeds were noticed by a man named Igo Etrich. Igo Etrich was an Austrian born flight pioneer who specialized in fixed-wing aircrafts around the turn of the century. Igo was inspired by the seeds, not of the Alsomitra vine, but of a very similar plant called Zanonia macrocarpa that possessed very similar seeds. In 1903, Igo developed some of the worlds first gliders using a shape very similar to the Alsomitra seed.

It is also believed that the shape and aerodynamic properties of the Alsomitra seed also inspired the Horten Brothers to develop the first "flying wing" aircraft, known as the Ho 229 for Nazi Germany in 1944. It was the first tailless fixed-wing aircraft to be powered by a jet engine. The shape of the seed lent itself very well to the design of this aircraft because it cut down on parasitic drag, or the drag caused by moving an object through a gaseous or fluid medium. It cut down on drag because it eliminated the need for a tail and it had a very shallow wing design.

This is a case where nature greatly inspired pioneers of human flight and a few little seeds helped change the world.

References:

"Alsomitra." Wikipedia, the Free Encyclopedia. 25 Sept. 2011.

"Horten Ho 229." Wikipedia, the Free Encyclopedia. 25 Sept. 2011.

"Igo Etrich." Wikipedia, the Free Encyclopedia. 25 Sept. 2011.

Walker, Matt. "BBC - Earth News - Vine Seeds Become 'giant Gliders'" BBC News - Home. 25 Sept. 2011.

By Colby Mann | Posted in student post | Tagged , | Comments (1)