February 27, 2007
Pitching the Nose Up and Down
Most modern airplanes have a control wheel in comparison to the old control stick.
When the pilot pushes the wheel forward, the elevators attached to the horizontal stabilizers move forward. The wind strikes the lowered elevators, which push the airplane’s tail upward and forces the nose downwards.
When you pull back on the wheel, the elevators are raised, pushing the tail down and the nose upwards.
Since the plane’s center of gravity is balanced, the motion of the tail always causes the nose to move in the opposite direction.
Trim
Trim is the adjustment of certain controls to eliminate the need for a pilot to constantly apply control pressure to hold the airplane at a desired control.
All airplanes have a forward and a rear trim that have to be applied to keep the airplane at a desired altitude.
Once the airplane is trimmed, the airplane will virtually fly itself without constant control input from the pilot.
Properly turning the airplane requires coordination. The pilot has to turn the wheel to bank the wheels through the action of the ailerons and the rudder pedals to which you apply corresponding pressure in the same direction as when you are turning the wheel.
Most turns are done with a bank angle of 30º.
I hope this installment has been informative for you! Your next installment will arrive shortly.
Sincerely,
SATISH K.S
Author of “The Insiders Guide to Becoming A Private Pilot”
February 26, 2007
The Propeller
The angle of attack of the blades of the propeller relative to an approaching air stream is called the pitch of the propeller blades. When the pitch is low, the angle of attack is also low. When the pitch is high, the angle of attack is also high. Changing the pitch changes the thrust characteristics of the propeller and the pull that it will generate. Most airplanes with engines of 150hp or less have fixed-pitch propellers because of the limited load capacity and speed range of smaller aircraft. Constant-speed propellers are more expensive and also the norm in larger aircraft. The pitch of the blades of a constant-speed propeller changes within certain limits. The internal mechanisms of the constant-speed propeller also change the pitch of the blade instantaneously.
In-Flight Propeller Effects
When the airplane is flying, there are several forces created by the propeller that affect the way the airplane flies. As the propeller rotates, the air flowing through it is twisted, creating a spiraling slipstream. The spiraling slipstream as it works its way out of the plane exerts a sideways force on the fuselage of the airplane and also upon the vertical tail surface.
Torque is the force that is generated in the direction opposite to the direction of rotation. American engines turn clockwise and hence, torque is a counterclockwise force from the pilot’s point of view. Generally, the torque is not felt by the pilot because of the design of the airplane.
The P-factor is an effect of the propeller that is most apparent when the airplane is at a higher angle of attack such as during lift off or during a climb. The P-factor will cause the nose to go left because of the propeller’s descending blade has a greater angle of attack than the opposite, ascending blade. This causes an unequal pull and the swinging of the nose that results consequently, is called a yaw.
The Engine
Airplanes generally use air-cooled engines which are very reliable and are lighter than liquid-cooled engines. They are also very efficient and run for extended periods of time. Increasingly, they are being designed to be quite fuel-efficient. Most of the engines have horizontal opposed cylinders similar to the engines used to power the original Volkswagen Beetle.
The ignition system
In an airplane, the engine has two complete and separate ignition systems that supply power to the spark plugs in the cylinders. The electrical energy that is needed to supply power to the spark plugs is derived from two magnetos or mags. The electrical system consists of a battery and either a generator or an alternator. The electrical system provides the energy to start the engine, run the radios, night flying lights, and other electrical equipment. The electrical failures that are possible in an electrical system have no effect upon whether the engine will work or not, which is an obvious safety mechanism.
There are two magnetos or mags in an airplane and because each one powers a totally separate and unconnected ignition system, including one of the two spark plugs in each cylinder, one entire ignition system could fail and the engine will continue to work on the other system. The ignition switch in the cockpit has 5 normal positions: off, left, right, both, and start. The start is spring-loaded and similar to a car, it will start the engine. The both position is the normal position for flight, allowing both ignition systems to work separately and independently. Left and right positions allow you to select one ignition system and disable the other system.
The primer injects raw fuel into the intake manifold to get the engine started. Some engines need a lot of priming to start especially in cold weather, whereas others need little to none.
I hope this installment has been informative for you! Your next, and final, installment will arrive shortly.
Sincerely,
SATISH K.S
February 24, 2007
Thrust and Drag
The propulsive force that moves the airplane forward is called the thrust. Propellers are airfoils and they act upon the air similar to a wing. The curvature in the propeller produces lift.
Propellers are slightly twisted so that their undersides strike the stream of oncoming air at a positive angle of attack. As the airplane moves forward, it experiences resistance to its motion or drag.
As the wing tilts upward to increase the angle of attack, the increased in induced drag is also caused by the body of the airplane or fuselage, as it naturally tilts up with the wing.
Center of Gravity
An airplane is a balance machine that can rotate on three axes around the center of gravity.
The exact location of the center of gravity will change with how the airplane is loaded up with cargo, people, and fuel.
There are specific limits known as the loading envelope, on exactly where the center of gravity should be, represented by a series of graphs.
It is important to always know where the center of gravity is and will be throughout the flight and also what the weight of the plane is before take off. If you begin your flight with the total weight limit, you will be ok because throughout your flight, your airplane is getting lighter as fuel is being consumed.
Again, thank you for signing up for this special mini-ecourse and I hope this installment has been informative for you! Your next installment will arrive shortly.
Sincerely,
SATISH K.S
Author of “The Insiders Guide to Becoming A Private Pilot”
February 22, 2007
Understanding Airplanes: 10 Things All Pilots Should Know!
In this, this article “Understanding Airplanes: 10 Things All Pilots Should Know!” , we are going to discuss: “Angle of Attack and Stalls and Stall Warning Devices.”
First, here is some basic information to help us get started:
An airplane flies on its wings. The wings produce a force that keeps the plane aloft, known as lift.
Lift opposes gravity and comes in various shapes and sizes. A jet plane has short wings while a glider has long wings. Most wings are designed to have camber, or curvature to enhance flight.
The word airfoil is also used to describe the curvature of the flight wing.
So with that out of the way, let’s move on to our first topic:
Angle of Attack and Stalls
Everything that an airplane does in flight depends on the angle with which the leading edge of the wing meets the oncoming stream of air.
This is also called the angle of attack.
If you go too slowly while pulling the nose higher to try to maintain flight, the wing will stall. A wing can be stalled at any speed, including the airplane’s top speed.
To accomplish a stall, all you have to do is to simply increase the angle of attack past its critical point, normally between 16º and 18º in a light airplane.
Gliders have no engine but they still are able to fly.
Their wings produce lift as a glider moves in the air just as the wings of a powered airplane do. Stalling the wing is what destroys lift not shutting off the engine power.
Stall Warning Devices
All modern airplanes have some sort of device to warn the pilot of an impending stall. The first is the aerodynamic warning that occurs when the entire airplane buffets, which is usually accompanied by the control wheel shaking in the pilot’s hands.
Almost all airplanes have also an additional warning that is visual or aural. There is a sensor on the leading edge of the wing usually in the form of a little metal tab mounted upward, which moves and activates an electrical switch. This in turn, activates a horn in the cockpit or turns on a bright red warning light.
Again, thank you for signing up for this special mini-ecourse and I hope this installment has been informative for you! Your next installment will arrive shortly.
Sincerely,
SATISH K.S
Author of “The Insiders Guide to Becoming A Private Pilot”
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