Why is there a downwash rather than simply a horizontal "backwash"? Think back to our previous discussion of pressure: a wing lowers the air pressure immediately above it. Higher up, well above the plane, the air is still at its normal pressure, which is higher than the air immediately above the wing.
So the normal-pressure air well above the wing pushes down on the lower-pressure air immediately above it, effectively "squirting" air down and behind the wing in a backwash. In other words, the pressure difference that a wing creates and the downwash of air behind it aren't two separate things but all part and parcel of the same effect: an angled airfoil wing creates a pressure difference that makes a downwash, and this produces lift.
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Now we can see that wings are devices designed to push air downward, it's easy to understand why planes with flat or symmetrical wings or upside-down stunt planes can still safely fly. As long as the wings are creating a downward flow of air, the plane will experience an equal and opposite force—lift—that will keep it in the air. In other words, the upside-down pilot creates a particular angle of attack that generates just enough low pressure above the wing to keep the plane in the air. Generally, the air flowing over the top and bottom of a wing follows the curve of the wing surfaces very closely—just as you might follow it if you were tracing its outline with a pen.
But as the angle of attack increases, the smooth airflow behind the wing starts to break down and become more turbulent and that reduces the lift. There's a big increase in drag, a big reduction in lift, and the plane is said to have stalled. That's a slightly confusing term because the engines keep running and the plane keeps flying; stall simply means a loss of lift. Photo: How a plane stalls: Here's an airfoil wing in a wind tunnel facing the oncoming air at a steep angle of attack. You can see lines of smoke-filled air approaching from the right and deviating around the wing as they move to the left.
Normally, the airflow lines would follow the shape profile of the wing very closely. Here, because of the steep angle of attack, the air flow has separated out behind the wing and turbulence and drag have increased significantly. A plane flying like this would experience a sudden loss of lift, which we call "stall. Planes can fly without airfoil-shaped wings; you'll know that if you've ever made a paper airplane—and it was proved on December 17, by the Wright brothers.
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In their original "Flying Machine" patent US patent , it's clear that slightly tilted wings which they referred to as "aeroplanes" are the key parts of their invention. Their "aeroplanes" were simply pieces of cloth stretched over a wooden framework; they didn't have an airfoil aerofoil profile. The Wrights realized that the angle of attack is crucial: "In flying machines of the character to which this invention relates the apparatus is supported in the air by reason of the contact between the air and the under surface of one or more aeroplanes, the contact-surface being presented at a small angle of incidence to the air.
Although the Wrights were brilliant experimental scientists, it's important to remember that they lacked our modern knowledge of aerodynamics and a full understanding of exactly how wings work. Not surprisingly, the bigger the wings, the more lift they create: doubling the area of a wing that's the flat area you see looking down from above doubles both the lift and drag it makes.
That's why gigantic planes like the C Globemaster in our top photo have gigantic wings. But small wings can also produce a great deal of lift if they move fast enough. To produce extra lift at takeoff, planes have flaps on their wings they can extend to push more air down. Lift and drag vary with the square of your speed, so if a plane goes twice as fast, relative to the oncoming air, its wings produce four times as much lift and drag.
Helicopters produce a huge amount of lift by spinning their rotor blades essentially thin wings that spin in a circle very quickly. Now a plane doesn't throw air down behind it in a completely clean way. You could imagine, for example, someone pushing a big crate of air out of the back door of a military transporter so it falls straight down.
But it doesn't work quite like that! Each wing actually sends air down by making a spinning vortex a kind of mini tornado immediately behind it. It's a bit like when you're standing on a platform at a railroad station and a high-speed train rushes past without stopping, leaving what feels like a huge sucking vacuum in its wake. With a plane, the vortex is quite a complex shape and most of it is moving downward—but not all. There's a huge draft of air moving down in the center, but some air actually swirls upward either side of the wingtips, reducing lift.
Photo: Newton's laws make airplanes fly: A plane generates an upward force lift by pushing air down toward the ground. As these photos show, the air moves down not in a neat and tidy stream but in a vortex. Among other things, the vortex affects how closely one plane can fly behind another and it's particularly important near airports where there are lots of planes moving all the time, making complex patterns of turbulence in the air. Left: Colored smoke shows the wing vortices produced by a real plane.
The smoke in the center is moving downward, but it's moving upward beyond the wingtips. Right: How the vortex appears from below. White smoke shows the same effect on a smaller scale in a wind tunnel test.
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Steering anything—from a skateboard or a bicycle to a car or a jumbo jet—means you change the direction in which it's traveling. In scientific terms, changing something's direction of travel means you change its velocity , which is the speed it has in a particular direction. Even if it goes at the same speed, if you change the direction of travel, you change the velocity.
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Changing something's velocity including its direction of travel means you accelerate it. Again, it doesn't matter if the speed stays the same: a change in direction always means a change in velocity and an acceleration. Newton's laws of motion tell us that you can only accelerate something change its speed or direction of travel by using a force—in other words, by pushing or pulling it somehow.
To cut a long story short, if you want to steer something you need to apply a force to it. Photo: Steering a plane by banking at a steep angle. Another way of looking at steering is to think of it as making something stop going in a straight line and start going in a circle. That means you have to give it what's called a centripetal force. Things that are moving in a circle or steering in a curve, which is part of a circle always have something acting on them to give them centripetal force.
If you're driving a car round a bend, the centripetal force comes from friction between the four tires and the road. If you're cycling around a curve at speed, some of your centripetal force comes from the tires and some comes from leaning into the bend. If you're on a skateboard, you can tilt the deck and lean over so your weight helps to provide centripetal force. In each case, you steer in a circle because something provides the centripetal force that pulls your path away from a straight line and round into a curve.
If you're in a plane, you're obviously not in contact with the ground, so where does the centripetal force come from to help you steer around a circle? Just like a cyclist leaning into a bend, a plane "leans" into a curve. Steering involves banking , where the plane tilts to one side and one wing dips lower than the other. The plane's overall lift is tilted at an angle and, although most of the lift still acts upward, some now acts sideways.
This sideways part of the lift provides the centripetal force that makes the plane go round in a circle. Since there's less lift acting upward, there's less to balance the plane's weight. That's why turning a plane in a circle will make it lose lift and altitude height unless the pilot does something else to compensate, such as using the elevators the flight control surfaces at the back of the plane to increase the angle of attack and therefore raise the lift again.
Artwork: When a plane banks, the lift generated by its wings tilts at an angle. Most of the lift still acts upward, but some tilts to one side, providing centripetal force that makes the plane steer round in a circle. The steeper the angle of the bank, the more the lift is tilted to the side, the less upward force there is to balance the weight, and the greater the loss of altitude unless the pilot compensates. There's a steering control in the cockpit, but that's the only thing a plane has in common with a car. How do you steer something that's flying through the air at high speed?
You make the air flow in a different way past the wings on each side. Planes are moved up and down, steered from side to side, and brought to a halt by a complex collection of moving flaps called control surfaces on the leading and trailing edges of the wings and tail. Great family feeling! Most coworkers were incredible, right theee in time of need.
Couldn't ask for anything better!! Leadership only cares about leadership. I had issues with how every NCO was only looking out for themselves and would disregard guidelines and technical orders just to make themselves look better on paper. Aim High. The Air force was and is a great start for young men and women to create a life with the opportunity to advance within the ranks as well as a jump start to higher education.
Fun place to work. The Air Force Base was a very nice place to work. Wish I was still there but the contract did not last. Would love to go back if I could. One of my best jobs. Great Experience. The Air Force was a huge part of my life for 6 years. It molded me into the responsible, punctual, and hard working man that I have become. It has helped me become a great leader but also a very good student. I appreciated all the time I spent serving and am grateful for the opportunities I was presented.
Great starter career.
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USAF shaped me into who I am today. Great start in life right out of highschool. Has its up and downs like any job. The people you meet along the way make it worthwhile. A typical day in the air force for me some thirty seven years ago started with role call followed by job assignments. Then out to the flight line to maintain aircraft. In that time I learned to work as a team. The hardest part of the job was extreme conditions.
The most enjoyable was serving my country. A good career launching point. The Air Force generally served me me well. I was able to serve the security needs of my country and acquire funding for education. If the military is an option you are considering, it is perhaps the most fulfilling of the options available. Review this company. Claimed Profile Review this company. Tessa strongly believes that science exploration should be exciting, inspiring, and accessible to students of all ages.
At BioBus, she is excited to help bring hands-on learning to the next level and hopes to inspire a new generation of kids to become creative, curious, young scientists. Contact Tessa Hirschfeld-Stoler at tessa biobus. Sedef Tinaztepe, Ph. She officially joined the BioBus staff in January , upon completing her Ph.
An experienced molecular biologist, Sedef has worked at a number of research and clinical laboratories, studying molecular genetics of diverse organisms such as humans, viruses, mosquitoes, and grasses. She believes that hands-on experiences play a critical role in developing an appreciation of science, and she is excited to inspire and support young scientists of NYC at BioBus. Contact Sedef Tinaztepe at sedef biobus. Marina Delgado, Support Scientist, graduated from Eugene Lang College of Liberal Arts, where she majored in Interdisciplinary Science——a field that addresses planetary health challenges through the gathering, management and interpretation of data.
Throughout her college career, she held the position of Lab Technician Assistant in The New School University's undergraduate laboratory and held three merit-based fellowship positions, the last of which focused in culturally-competent science education with a strong foundation in social justice. As a bicultural Latina herself, having the opportunity to give young women of color a positive experience with science is especially valuable to her.
Marina believes in BioBus's mission of bringing explorative science education to low-resourced communities, and is especially excited about the opportunity to give back to her own community, using her first language to expand BioBus's reach among communities of color. Contact Marina Delgado at marina biobus. Her research focus on the neuroplasticity of learning and memory is entwined with a long history of educational outreach and science communication.
Rosemary loves the unique experience BioBus creates for students to question and investigate their world. Contact Rosemary Puckett at rosemary biobus. Ashley Pirovano, M. After earning her graduate degree, she worked as the Laboratory Supervisor and Adjunct Professor at Marymount for two years. Ashley is thrilled to be working for BioBus because she is very passionate about science outreach and loves showing students of all ages how fun and exciting science can be!
Contact Ashley Pirovano at ashley biobus. Luis Perez-Cuesta, Ph. In he came to NYU to study learning-induced plasticity in the mouse brain cortex. Luis also has a deep passion for teaching, which he has done since he was an undergrad. He believes science literacy is an essential tool to empower people to make rational decisions and advocate for themselves in their civic life. Contact Luis Perez-Cuesta at luis biobus.
Maria Mazin, Ph. D, Community Scientist, is an entomologist with a background in Agricultural Sciences. She obtained her PhD in Entomology and International Agriculture and Development from The Pennsylvania State University while studying the ecology of mushroom flies within mushroom farms as well as their mutualistic association with parasitic fungi.
She also conducted social studies within farmworker communities aimed at improving pest management educational and outreach efforts towards Hispanic farmworkers. Maria strives towards working within the intersection between biological sciences and social development and believes that science should be accessible to everyone at any level. Contact Maria Mazin at maria biobus. He joined BioBus December to pursue his passion of introducing students to student outside of the classroom. Prior to his arrival at BioBus David was an activist who focused on social and educational reform which led him to work on staff for Teach for America.
His appreciation for the sciences stems from the influence of his chemist father. Contact David Yap at david biobus. He is an experienced educator, having taught biology, environmental science, and sustainability for the last five years both in New York and internationally in Northern India. As part of his thesis, he collected fecal samples from lemurs in Madagascar and brought them back to a lab at Emory for analysis. More recently, on a personal front, Ian has become really interested in waste and trash in NYC and has been collecting and photographing all his non-recyclable, non-compostable waste at the end of every month in an effort to send zero waste to landfills.
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You can find Ian riding his bike around Brooklyn or on the Hudson River Greenway on the way to work every day. Contact Ian Fried at ian biobus. He received a B. In addition to that one time he 3-D printed cookies, Ben has worked in half a dozen academic labs on projects ranging from ceramic nanoparticles to laser crystallization of metallic thin films to creating bio-composite hygroscopic actuating materials. Ben is very fond of lasers. Contact Ben Miller at b. Since her first experience with science advocacy through the BioBus in New York City, she has boarded countless planes, trains, boats, and bicycles pursuing a love for science communication.
She traveled to Kyrgyzstan to work as a beekeeping instructor, to France to research chemical communication in native bees, and to Thailand to learn about beehive fences that deter farm-raiding wild elephants. Most recently, she spent a year of independent travel in Southeast Asia as a Michael C. Rockefeller Fellow. She returned to the US to work for the BioBus and is firmly convinced that she has finally re-boarded the best vessel of science education she has yet to find in the world. She graduated high honors with a B. She loves bees and breakfast.
During her doctoral research at the Leibniz Institute for Neurobiology in Germany, she became fascinated with the mysteries of the human brain, while also experiencing new cultures and cuisines. She is now focused on scientific outreach, and spreading the feeling of awe and wonder of science beyond the universities and academic laboratories, especially to children and youth. Contact Ela Joseph at ela biobus. He is an experienced educator and is certified as a public school teacher in the states of Florida and New York.
He has also taught in the private sector. Like Dr. He handles logistics for the BioBus and is the main point of contact for schools and communities that are interested in having the bus visit. Contact Danny Valdes at danny biobus. She graduated from Hamilton College in with a B.