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Fundamentals of Flight
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Exploring the elementals of aeronautics
Submitted By admin on 10/05/14
Aubrey Falconer, admin, Documents, articles, science, physics 
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Russian Kalinin K-7 (Visualization)
 
 
Flight: A triumph of engineering which permits the traversal of our world from a whole new dimension!
 
Flight can be divided into three basic groups:
  1. Gliding, in which kinetic energy is lost as distance is traveled.
  2. Floating, in which the aeronaut is carried about by currents of air.
  3. Powered Flight - in which thrust employed for vastly greater range and maneuverability.
Though Fish, Spiders, Snakes, Ants, and a Myriad of other creatures have employed flight for countless ages - we now understand the principles involved and can make use of them, even if we still aren't anywhere near matching the effiency of nature. Many of the same forces which keep airliners aloft are directly applicable to your paper airplanes - and you can learn about them in this article.
 
 
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Lift:
 

 
As visualized in the Venturi Meter to the right, air flowing through a pipe has to increase it's speed when passing through a constriction - and when it's speed increases, it's pressure decreases. The effect that results in the water bubble shifting to the left side of the meter (where the air pressure is lower) is known as Bernouli's Principle, and it's key to understanding how airplanes stay in the sky.
 
When air flows across a shape known as an airfoil (such as the wing of an airplane), the air on the curved top side has to travel faster than the air on the relatively flat bottom side. Thus, the higher pressure on the bottom side exerts a lifting force on the airfoil.
 
When an airfoil slices into the air at an angle instead of directly inline with it's motion, it is said to have an "Angle of Attack" (AoA). The steeper this angle is, the more air has to travel over one side of the airfoil and less over the other side, which causes more lift (and drag).
Stall
Source: Wikipedia

The greater an airfoil's AoA, the less smoothly air flows over it. When an Airfoil's AoA is too high and it's speed is too low, laminar (smooth) flow of air over the wing is replaced by turbulence and the airfoil generates lots of drag and very little lift. This condition is known as a stall, and generally results in a loss of altitude as the plane falls and gathers speed to resume flight. On certain aircraft, it can result in a complete loss of control and a catastrophic crash! Some high performance fighter jets are designed for supermaneuverability (to be controllable during stalls), which allows them to perform amazing maneuvers such as Pugachev's Cobra.
 
Drag:
 
When a plane is flying slower than the speed of sound, subsonic aerodynamics describes the two primary forces that slow it down as Form Drag and Induced Drag. Form drag is caused by turbulence as air flows over the plane, and is minimized by long, tapering trailing edges on each shape of the hull to keep air flowing smoothly along it. Wherever air encounters an angle too sharp to flow smoothly over (just as in airfoil stalls described above), excessive turbulence and drag results. The faster an object is moving, the vastly greater it's induced drag is! Objects in free fall eventually reach an equilibrium between gravity speeding them up and drag slowing them down, and this is described as their terminal velocity.
 
Induced drag is related to the redirection of airflow to generate lift - and since planes have to redirect airflow most to stay aloft at low speeds, induced drag decreases as an airplane's speed increases. An aircraft's maximum efficiency is obtained at the speed where induced and form drag are equal. When an airplane is rotated on it's yaw axis so that it points to the side of it's direction of travel, it's form drag is increased and the condition is described as a side slip. Aircraft are equipped with tail rudders to counteract this problem and aid in various maneuvers.
 

Source: Wikipedia

Stability:
 
Dihedral angle describes the upward sweep of an aircraft's wings. When the wings of an airplane form a slight "V" shape when viewed along it's length, the lower wing generates extra lift when the aircraft begins to roll and automatically stabilizes it. If your paper airplane tends to dive left or right when flying, it definitely needs more dihedral!
 
Control surfaces such as ailerons, elevators, and rudders allow an aircraft to modify the shape (and therefore performance) of it's airfoils in flight to control it's attitude. You can add control surfaces to the trailing edges of the wings on your paper airplanes to stabilize their own flight: A curve to the left or right can be cured with an upward flap on the opposite wing, and nosedives or stalls can often be corrected by adjusting the "flaps" on both wings up or down.
 
Spin Stabilization is employed from frisbees to rockets for a simple stability solution - but where rapid rotations aren't an option, Fly by Wire systems feed sensor inputs into a computer to calculate the exact control deflections necessary to keep high performance aircraft (even RC ones!) in the sky.
 
 
Paper Airplanes:
 
Bonus Questions:
  • What is a "wind tunnel", and for what are they used?
  • How can an airplane pilot recover from a stall, or a helicopter pilot land when their engine dies?
  • What does the term "terminal velocity" refer to?
  • Why do "stealth" fighter jets look so angular? (Hint: this answer has very little to do with aerodynamics)
  • Why are helicopters so much slower than airplanes? (Hint: visualize the relative airspeed of each side of the main rotor as the helicopter soars through the sky)

» Reply to Comment
Re: Fundamentals of Flight
1 hour - 113v
Posted 2010/05/22 - 5:56 GMT
Aubrey,
 
That is amazing! Thank you so much for all your hard work! Incredible! You are truly a wonderful addition to TLE.
 
Tirzah (Mandy)
» Reply to Comment
Re: Fundamentals of Flight
4 days - 9,839v
Posted 2010/07/21 - 0:53 GMT
Because of the receding wing affect, when a helicopter go to fast as the rotors went around on one side they would have the speed of the helicopter plus the speed of the rotors turning. On the other side you would have the opposite, causing the helicopter to lean over and potentially flip.
a wind tunnel is a tunnel in which air is blown in by large turbines at a set speed, they are used to experiment with aerodynamics on different things in a controlled environment.
when the engine dies in a helicopter the pilot can lower the pitch as far as possible and let the helicopter fall, as it goes down the airflow will cause the rotors to turn and slow the decent.
nice article aubrey:)
» Reply to Comment
Re: Fundamentals of Flight
5 days - 26,111v
Posted 2011/08/29 - 1:25 GMT
Hi! I love anything that has to do with flight. I want to be a pilot for United Airlines with 767s. Sorry I posted so late. I just love this article!
» Reply to Comment
Re: Fundamentals of Flight
1 week - 32,767v
Posted 2012/08/09 - 19:58 GMT
Say, is that "Russian Kalinin" an airplane??? Looks really weird for an airplane!
» Reply to Comment
Re: Fundamentals of Flight
2 days - 11,431v
Posted 2013/07/14 - 20:38 GMT
Yeah, it was back when people thought that installing more prop engines on the aircraft would make it fly farther, higher, and faster.
» Reply to Comment
Re: Fundamentals of Flight
4 days - 9,791v
Posted 2013/07/15 - 18:19 GMT
To add to that:
 
----
 
The K-7 was actually built and successfully flown, although there were problems. However, during one test flight, it crashed and killed 15 people. :(
 
Its wing, at the thickest point, was 2.7m thick, just to put it into scale. Imho it was one of the first "flying wings" (while it did feature two tails, and a pair of fuselage-like booms, it had no fuselage.)
 
There were loads of seats INSIDE the wing - a very sensible design, imo. Would lead to a smoother flight for the passengers if someone tried it nowadays, but vibrations from the engines on the K-7 caused a serious problem when it comes to comfort lol.
 
----
 
Glad you brought this post back, Sven. It's great, I hope loads more people get to read it (and hopefully understand it, too, lol).
» Reply to Comment
Re: Fundamentals of Flight
1 week - 32,767v
Posted 2013/07/15 - 18:35 GMT
IMHO that's a graphic render of the K-7 which is impressive, but innacurate. Refer to Wikipedia for actual, far less impressive, six engined real version
» Reply to Comment
Re: Fundamentals of Flight
4 days - 9,791v
Posted 2013/07/15 - 18:47 GMT
It's an artist's impression of what later models would have looked like, I guess.
 
So @lamp, the plane pictured did not exist, but the K-7 did. A google search should return all you need to know and more, lol.
» Reply to Comment
Re: Fundamentals of Flight
2 days - 11,431v
Posted 2013/07/17 - 5:50 GMT
Oh, haha. I just saw Lamp's comment and thought it was a new comment. xD And yes, I love this post! 
 
 
Speaking of flying, does anyone have FSX? :P 
» Reply to Comment
Re: Fundamentals of Flight
4 days - 9,791v
Posted 2013/07/17 - 7:52 GMT
X-Plane here... it's an eight-year-old copy though, lol, so the graphics is pathetic.
» Reply to Comment
Re: Fundamentals of Flight
2 days - 11,431v
Posted 2013/07/24 - 5:17 GMT
Ah okay. Lol


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