# FINAL

Last webpages viewed:

The last thing I need to learn a little more about is banked turns during flight

http://www.aviastar.org/theory/basics_of_flight/flight.html

When airplanes turn it is called banking. Most airplanes lost altitude and airspeed when banking because the angle of attack is changed and the idea that lift is nearly  perpendicular to an airplane’s wing. Airplane pilots counter attack this loss of airspeed and altitude by increasing  the speed of the plane. This increase of speed allows more air to be deflected downward which allows the plane to maintain lift.

Learning:

After a week of research on the topics of airplanes and the causes of lift, I feel I have a strong understanding of the physics of airplanes. From the two hotly debated theories about the cause of lift, I chose the side of Newton’s laws because it made much more sense to me than the theory involving Bernoulli’s principle. Visualizing my hand outside the car window at a high speed clinched my choice as to the reason why airplanes can fly. As I increase the angle of attack of my hand, my hand flies upward. The reason: the amount of air deflected downward from my hand, creates a reactive force that causes my hand to fly upward.

Objectives:

What causes airplanes and other machines to fly? What does air pressure have to do with it?

I feel I am at 99% for understanding this objective just because none of the two theories have been disproven.

Do different machines have different ways of creating lift?

Didnt really focus on this objective as I combined my project with Katrina’s. However, many sites argument that helicopters are able to fly because of the theory based on Newton’s laws.

How do airplanes and other machines take off and land? What are the differences?

I was able to learn a great deal about take off and landing during my research. I understood the similarities and differences and I am ready to share this with the class.

what are the different mechanics that help an airplane take off and land?

Similar to the objective above, I feel I have a strong understanding of this objective.

How does thrust and drag affect airplanes when flying?

I focused a little bit on this objective because Katrina was going to focus more on this. I understand a substantial amount about this topic, but I will leave it up to Katrina to describe.

Overall I feel I am ready to present and all of the surprises and misconceptions I had at the beginning of this project are now gone, except for the confusion on what theory of lift is truly right

here is my last video

All of the physics I have learned is shown in this difficult landing attempt on St. Maartan, a island in the Caribbean

the pilot does a masterful job at one of the top 10 most dangerous airports to land at because of its short runway and close proximity to beach goers

# Day FOUR

Webpages visited:

http://home.comcast.net/~clipper-108/lift.htm

I visited this site to better understand the cause of lift..

The argument of Bernoulli’s principle which says that if air speeds up the pressure decreases is the main argument for an airplane’s lift. The high pressure below the plane is trying to move towards the low pressure which causes lift. However, this argument only holds true if the principle of “equal transit times” is true. Many experiments have shown though that air on the top of a curved wing usually travels faster than the air underneath the wing, which muddles the theory that air must travel faster over the top of the wing to reach the same point at the same moment the air underneath the wing reaches there (equal transit times)

http://danielmiessler.com/blog/why-planes-fly-what-they-taught-you-in-school-was-wrong

I have more belief in the second theory that uses newton’s laws to describe lift. I could better visual this method because its like putting your hand outside the car. If you hold it parallel to the wind, you are able to control your hand with relative ease. However if you increase the angle of attack ( described in previous post), more wind is diverged downward and your hand moves upward because the massive amount of lift force. Using Newton’s third law of reactive forces, this theory makes more sense to me than Bernoulli’s principle. However the difference in air pressure theory still intrigues me and it might be that both these theories cause lift.

http://www.decodedscience.com/airplane-wings-how-lift-is-created/6595

Lift created by different parts of the wing:

The force of lift completely depends on the interaction of air molecules with airplane wings. Consider a single plate of the wing exposed horizontally an even airflow in the air

1. The plate is exposed to the airflow.
2. Air molecules slide past the plate.
3. A very few molecules interact with the plate, and that interaction too is at a slanted angle providing low static pressure.

Airplane wings are never built in-line with the fuselage of the aircraft. These wings are always installed at a slight angle. This angle of the wing is termed as the angle of inclination When this inclination is applied to the plate:

• Air molecules strike against a greater portion of the plate.
• Much of the plate is exposed to perpendicular strikes of the air molecules.
• The air mass exerts a reactive force that creates the lift of the aircraft

Explanation of wing:

the wing should be considered as a object that scoops the air, diverting the air from the horizontal to the angle of attack. Also the lift of a wing is proportional to the amount of air diverted downward, which is also proportional to the wings area.

Mechanics of an airplane that help during take off and landing:

Just to restate the airplane’s wings create the lift necessary to flow. The slats and flaps help to create lift by enlarging the surface area of the wing, which allows more air to be diverged downward. This increase in lift is important for both take off and landing. Spoilers are also an important component to the wings of an airplane. These are small plates that are on the back of each wing and are used to disrupt the flow of air, decreasing lift ( used during landing).

Summary of learning:

From today’s research I feel i am almost at 100% for understanding the basic principles of lift and the components of an airplane that allow it to take off, stay in the air, and land. However, i am still confused what theory actually causes lift. I feel that there is an on going debate to this topic so i should just pick one and roll with it

Misconceptions/surprises:

Not many surprises today

I am just confused on the actual cause of lift and i will try to figure out which theory i stand by soon

Videos/photos:

here is a video that describes in depth the forces on an airplane in flight

# Day THREE

Webpages/Articles found:

http://discovermagazine.com/2001/apr/featphysics#.UYm894IU5BR

This article gives interesting insight on what causes lift for an airplane. The well known theory of Bernoulli’s principle works on the idea that as a wing passes through the air the its shape make the air travel more over the top of the wing than beneath it. This creates a higher pressure are beneath the wing than above it. The pressure difference cause the wing to push upwards and lift is created.

However, there is a new  theory to lift, which is based primarily on Newton’s laws and the Coanda Effect. The theory is that lift is a reactive force. As air travels over the wing, air is bend down because of the tendency of the air to stick to the surface it is traveling over (Coanda Effect). To bend the air down, the wing exerts a force on the air. There is an equal and opposite reaction to this force: the air exerts an upward force on the wing. A pilot can increase this lift force by traveling faster or by increasing the angle of attack (explained below) which both divert more air downward,increasing lift due to Newton’s three laws.

http://howthingsfly.si.edu/aerodynamics/alternative-theories-lift

Another site,however, says that the downward push on the air results from air pressure differences on the wing “it is an effect of lift, not the cause of it”.

Take off:

The relationship between angle of attack and lift:

angle of attack is the angle between the direction of the wind and the direction the wing of the airplane is pointed in.

At a small angle, most of the lift comes from the coanda effect and newton’s three laws. As the angle increases, some of the air is deflected downward off the bottom of the wing, which causes lift because of equal and opposite forces (newton’s laws). There is a critical angle of attack where the air stream begins to separate from the surface of the wing and starts a swirling motion which decreases lift and the airplane might stall.

Turns during flight:

Airplanes must be banked to make a turn because the lift force is also used to make the airplane turn. This is similar to normal force on a banked surface. When the wings are level, lift acts directly opposite to gravity. However,when the airplane is banked, gravity acts in vertically, but now the lift has a horizontal component.

Different parts of an airplane that affect lift:

http://www.grc.nasa.gov/WWW/k-12/airplane/airplane.html

WInglets are on the end of each wing on modern airplanes and these are put in place to decrease drag. High pressure on the lower surface creates a natural airflow that makes its way to the wingtip and curls upward around it. When flow around the wingtips streams out behind the airplane, a vortex is formed. These twisters represent an energy loss and are strong enough to flip airplanes that blunder into them. Flaps are deployed downward on takeoff and landing to increase the amount of lift produced by the wing. As the flaps are extended, the curvature of the wing is increased. Due to the coanda effect and newton’s laws, more air is bent downward, which causes a greater lift force.  Slats, like flaps, are used at takeoff and landing to produce additional force and are on placed on the front of the wings. The spoilers are mechanisms that disrupt the airflow over the wing to decrease lift and increase drag.

Summary of Learning:

From my research today I learned a great deal about lift, the effect of the angle of attack, the process of turning an airplane, and the different mechanics of an airplane which allow it to take off, fly, and land. I still need to learn more about the mechanics to allow a plane to cover its journey from the ground to the air and back to the ground.

percent: 45-50%

Misconceptions/surprises:

The biggest misconception I had today was that the air travels faster over the top of the wing to cover the same distance air travels at the bottom of a wing. I thought because of this the greater velocity of the air and the lower pressure, lift occurs because of the pressure difference. This is confusing because in essence the work done by the plane allows it to fly, which is wrong. Newton’s laws better explains the lift force that allows planes to fly. However, i am still confused because other sources say that the air that is pushed down from the top of the wing that creates an equal and opposite force that creates lift is caused by a difference in air pressure. So it might be that both Bernoulli’s principle and newton’s laws cause lift.

# Day TWO

Set of sources used on DAY TWO:

Webpages used today:

http://www.fi.edu/flight/own2/takeoff.html

How do airplanes land? Pilots release their spoilers which increase the drag force to slow down the plane. This also decreases the lift force because the air on top of the wing is traveling at a lower speed which decreases the pressure difference between the top and bottom of the wing.

Interestingly enough, after pilots release the spoilers they also extend their flaps so the airplane doesn’t fall out of the air and has a more gradual descent.

This academic journal focuses on the effect of the spoiler on the lift of an airplane. Spoilers are placed on the top of each wing and extend upward to “spoil” the even airflow. The spoiler is used to create a stall over the end of the wing, which decreases lift. Spoilers are also to increase drag.

http://howthingsfly.si.edu/sites/default/files/attachment/ScienceinyourAirplaneSeat.pdf

As the airplane is taking off, pilots increase the flaps on the back of each wing. This creates a larger curve on the wing, which creates more lift. The pilot then retracts the flaps when the plane is at its premium altitude, which makes sense as the need for lift is minimal.

Summary of Physics Learning:

From my research today I was able to understand the basic principles of how an airplane takes off and lands. I learned about a couple of mechanics on an airplane that help an airplane carry out these tasks, such as flaps and spoilers (which help increase and decrease lift). This was one of my objectives, but i want to go more in depth on this tomorrow.

Percentage: 25-30%

Surprises and Misconceptions in Learning:

From my research today i was surprised by how planes actually land. I thought planes just decreased lift, but it is far more than that. To safely land an airplane they must decrease lift because also counteract that by increasing lift so the airplane doesn’t fall out of the air. Also airplanes deflect exhaust air forward when they touch down to push the thrust force forward, which is turn slows down the aircraft (which i didn’t know).

Extra videos/pictures:

this video gives a quick explanation of the physics behind take off and landing

# Introduction

Topic Choice: How do different machines (like airplanes and helicopters) fly? : The effects of air pressure

I chose this topic because i am interested in aviation and the effects of air pressure on the world around us.

Learning Objectives:

What causes airplanes and other machines to fly? What does air pressure have to do with it?

Do different machines have different ways of creating lift?

How do airplanes and other machines take off and land? What are the differences?

what are the different mechanics that help an airplane take off and land

How does thrust and drag affect airplanes when flying?

Are you partnering with someone?

Yes I am partnering with katrina

she is talking about the underlying principles of air pressure and I am talking about landing, taking off, and the physics in general of a plane’s journey