Instruments in an aircraft have two purposes: to display current flight conditions (such as airspeed and altitude) and to notify of unsatisfactory or dangerous conditions. Standardized colors are used to differentiate between visual messages, with green as a satisfactory condition, yellow for caution or a serious condition that needs monitoring, and red as a color for unsatisfactory or dangerous conditions.

Most aircraft use annunciator lights that turn on when something demanding the crew’s attention happens. These use the aforementioned colors in a variety of presentations. Individual lights near the associated cockpit instrument or a collective display of lights for various systems in a central location are common, with words labeling each light to help identify problems quickly and plainly.

On complex aircraft, numerous systems and components must be monitored and maintained. Centralized warning systems can announce critical messages about these systems and components in a simple and organized manner on a central annunciator panel in the cockpit. These analog aircraft warning systems may look different in various aircraft, and their design depends on the manufacturer’s preference and the systems installed on the aircraft itself.

Master caution lights are used to draw the crew’s attention to a critical situation, and to the annunciator panel that will describe the problem. These master caution lights are centrally wired and illuminate whenever any participating systems or components that require attention. Once notified, a pilot can cancel the master caution, but a dedicated annunciator light stays illuminated until the situation causing the warning is fixed. Cancelling the alert resets the master caution light to warn of a subsequent fault even before the initial fault is corrected.

Accompanying the visual warning systems, aural warning systems work to audibly inform pilots of developing situations. Various tones and phrases sound in the cockpit to alert the crew of certain conditions. For example, a bell will sound if the throttle is reduced and the landing gear is not in a down and locked position.

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An aircraft propeller consists of two or more blades mounted on a central hub connected via a shaft to the engine. This can be either an extension of the engine’s crankshaft in low-horsepower engines, or a propeller shaft geared to the crankshaft in high-horsepower configurations. In either case, each blade of the propeller essentially acts as a rotating wing, which produces force that creates thrust to pull or push the aircraft through the air. The vast majority of aircraft have a “tractor” arrangement, where the propeller is mounted towards the front of the fuselage and pulls the aircraft, but there are examples of “pusher” arrangements where the propeller is mounted in the back and pushes the aircraft through the air.

In either case, the engine rotates the airfoils of the blades through the air at high speeds, and the propeller transforms the rotary motion of the engine into thrust. This is a conversion of brake horsepower to thrust horsepower, which is not perfectly efficient. Most propellers operate at roughly 50-87% efficiency.

A propeller can be described as a twisted airfoil of irregular platform. Blades do not remain flat, but twist from base to tip, changing their airfoil along the way. The blade shank is the thick, rounded portion near the hub, designed to give the propeller blade strength. The butt, or base or root, is the end of the blade that fits into the hub, while the tip is designated as the last six inches of the propeller blade.

Blades are shaped similar to aircraft wings, with a bottom side that is flat while the other side is cambered or curved. The flat side is also referred to as the blade face, since it is the side facing the pilot in a conventional tractor arrangement.

There are multiple forces that exert themselves upon propeller blades as they rotate. Centrifugal force tries to throw the rotating propeller blades away from the hub, while torque bending force bends the propeller blades in the opposite direction of rotation. Thrust bending force bends the propeller blades forward as the aircraft is pulled through the air, and aerodynamic twisting force creates a rotational force around the center of pressure, causing the blade to pitch to a lower blade angle. All this means that a propeller must be able to withstand severe stresses, which get stronger near the hub caused by centrifugal force and thrust. It is important to inspect your aircraft’s propeller blades frequently ensure there are no signs of wear or tear upon them. Fluttering, a type of vibration where the ends of the blades twist back and forth at high frequency, is also a sign of failing rigidity in the propeller blade and should be addressed immediately when it is identified.

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You can fold up a piece of paper, give it two wings, and watch it fly. However, you do not have the ability to pick where the paper plane lands or alter how fast it gets there. This is because you most likely did not add propellers to your paper plane. Two recognizable features of an aircraft are the wings and the aircraft propellers. Both of these parts allow the pilot to control the aircraft and navigate it through the skies. Aircraft wings and propellers each manipulate the air in which the aircraft is flying in. The wings, also known as airfoils, direct and redirect the airflow around the aircraft. The propellers are designed to produce thrust, thus, moving the plane forward.

Wings generate force and streamline the air during different stages of flight. The most common wing design that most commercial aircraft feature was developed by Richard T. Whitcomb. The wing features a curved surface on top and a flat underside. Although Whitcomb originally designed the wing to have a flat top and curved bottom, the overall design of wing helped to overcome the problem of an air disturbance called drag. The flat surface works to hinder the effect of the standing shock wave, forcing the air beneath the aircraft. The curved portion of the wing helps to squeeze the air up and over, creating the lift of the aircraft.

On commercial aircraft the propellers are usually located under the wings. While both aircraft parts work together to move the plane through the air, the propellers are creating movement whereas the wings are controlling movement. The underlying principle of both parts can be linked back to Newton’s Third Law: For every action there is an equal and opposite reaction. As the propellers rotate through the air, they push the air behind them, therefore moving the aircraft forward.

The substance in which the propeller is moving through determines the rate at which the propeller needs to move. In wood or a similarly dense material, a screw would move slowly. In air however, a propeller can turn significantly faster. The rate at which a propeller moves is measured in revolutions per minute (RPM). The blades of a propeller are connected to a central hub. If you were to take a cross section of the propeller blade, it would actually resemble a wing. Just like the curved top in the wing, the propeller blades are also curved. This design creates a variation in the amount of thrust produced  by the propeller.

The wings and propellers of an aircraft are essentially pieces of equipment that collaboratively keep an aircraft in the air and moving forward. The wings control the air and push it downwards, therefore allowing the plane to rise up and carry its own weight. The propellers, powered by an engine, push the air backwards creating lateral thrust forward.

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Compressors reduce air volume and therefore increase its pressure. This device is utilized in engines to increase the amount of air allotted to the combustion chamber— the more air that can be added, the more an engine can burn and produce more power. An air compressor specifically compresses air, as opposed to other compressors that condense different types of gases. There are many types of compressors that have been developed for various applications, and new technology and designs have increased efficiency throughout the years.

Positive displacement compressors include piston compressors, scroll compressors, and rotary screw compressors—all of which operate with a constant flow. They have a cavity which allows gas to enter the machine at atmospheric pressure. When the chamber becomes smaller, it decreases the gases volume (compresses it) and increases the pressure. Single acting piston compressors compress gas on one end of the piston while double acting compressors compress the gas on both ends of the piston. Both, the single and double acting compressors, can incorporate multiple compression stages in order to create the desired amount of pressure. They are ideal for high pressure applications. Screw compressors trap and seal the gas between rotors. The rotors mesh the gas as they rotate, push it into smaller spaces, and cause it to compress. Scroll compressors have two spiral shaped rotors that are fixed against each other. When the spirals move, the gas cavities get smaller and compress it. Positive displacement compressors produce the same flow at a given RPM.

Radial dynamic compressors are often used for powered flight and are commonly referred to as centrifugal and turbo compressors. In a dynamic compressor, impellers accelerate the gas and the diffuser slows the gas down in order to increase its pressure. Centrifugal or turbo compressors are most commonly used in chemical and petrochemical applications, power generation, industrial gases, and steel, glass, and fertilizer manufacturing plants.

In addition, there are fixed speed and variable speed driven (VSD) compressors. Fixed speed compressors run at one fixed speed and are efficient when operating on full load. When the unit stops compressing gas, fixed speed compressors become inefficient because it is still turning the motor and using power; however, it eventually stops. A VSD adjusts to the amount of gas that is being required: it only utilizes the energy that is required to produce the compressed gas. Because of this, a VSD is much more efficient.

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Almost all modern turbine engine aircraft incorporate air compressors in their systems. Turbine engines use an air compressor to increase the pressure of incoming air before it enters the combustor. There are two types of air compressor used in aviation, axial and centrifugal.

Axial flow compressors are most commonly used in large turbojet and turbofan engines. It is more utilized by aircraft equipped with these engines because of its structure and its capacity to be constructed in a multi-stage system. An axial compressor relies on the functionality of rotors and stators to manipulate air flow as it travels parallel to the axis of rotation. Incoming air flows through blades that are attached to the central shaft (rotors) which increase its velocity and pressure. Simultaneously, the air flows through stationary fixed blades, or stator blades. The stationary blades are fastened to an outer casing, and act as a diffuser, slowing the air flow down. This entire unit is connected to a shaft which unites the compressor with the power turbine.

A single air compressor like the one described above has the capacity to be linked together in a series of axial compressors to create a multistage axial compressor system. This configuration allows air pressurization to increase considerably. Most turbojet and turbofan engines use this compressor because of this capability.

Centrifugal compressors have an airflow that is perpendicular to the axis of rotation. These systems feature an airfoil as well but rely on an impeller and a diffuser. An impeller rotates and adds velocity the air flow passing through it. A diffuser surrounds the impeller. It has small air channels that direct air away from the impeller reducing velocity and converting it to high pressurized air. Because of their construction, a multi-stage centrifugal air compressor is not feasible. Their use of perpendicular air flow causes the structure of a centrifugal compressor to be wider than an axial unit, which increases aircraft drag. As a result, these air compressors are primarily seen in turboprop engines and small aircraft.

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It’s the new normal, to be able to fly from point A to point B, thousands of miles away, in a matter of hours. And yet, the mechanics of this “simple” act are still unknown to a vast majority of people. We take for granted all the advancements and innovations that it took to allow us to travel so far and so fast as regularly as we do. So, it makes sense that to the average person, “turbonormalizing” and “turbocharging” sound like they mean the same thing. Or they remind people of the Fast and Furious franchise. Surprisingly, that’s not entirely wrong.

While the automotive industry and aviation industry are actually very different and share very few similarities, turbocharging is something common in both fields. In general, an aircraft turbocharger is a forced-induction device that increases an internal combustion engine’s efficiency and power output by forcing extra compressed air into the combustion chamber. This allows cars to be faster and more powerful with less requirements. So yes, upgrading your car’s engine to the levels seen in the Fast and Furious films is possible.

Turbocharging in aircraft is the same as it is in cars, except it’s more important. Pilots prefer to fly at higher altitudes because higher altitudes mean less aerodynamic drag, which means more efficiency. But higher altitudes also mean less dense air pressure, which means less efficiency. And the lower efficiency as a result of less air pressure is far greater than the higher efficiency as a result of less aerodynamic drag. So, turbochargers, and turbonormalizers, are used to augment the aircraft engine and make them more powerful and more efficient. Both systems work by gradually closing the wastegate as the aircraft climbs to higher altitudes in order to control how much of the exhaust gases are released. Closing the wastegate increases the amount of exhaust gases being forced past the turbine wheel, forcing the turbine to higher RPMs, leading to more compressed air available for the engine. But what’s the difference between turbocharging and turbonormalizing?

While both turbochargers and turbonormalizers make the engine more powerful and more efficient, they work in slightly different ways. A turbocharger pushes compressed air into the combustion chamber, allowing the engine to work as if the aircraft were flying at about 6 to 10 inches from sea-level. Meanwhile, turbonormalizers push enough compressed air into the combustion chamber to mimic the conditions of flying at perfectly sea-level. Turbochargers are comprised of an exhaust gas-driven turbine wheel in a cast-iron scroll housing and a compressor wheel in an aluminum scroll housing; both wheels are mounted on a rotating shaft. On the other hand, turbonormalizers include the turbocharger as one of several components.

Depending on what kind of turbocharging system or turbonormalizing system and wastegate your aircraft uses, you might need more or less frequent maintenance and repair. And for you all your aircraft turbocharging and turbonormalizing system parts, you have us at Methodical Purchasing.

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Propellers are, single-handedly, the most noticeable part on an aircraft. Using energy from the engine to spin, the aircraft propeller is used to create thrust by rotation.

Depending on the type of aircraft, the propeller can look very differently. The number of blades increases as the size of the aircraft engine increases, to ensure proper power distribution. And, propeller blades can vary in material, such as wood, fiberglass, composites, and metals, depending on how strong or durable they have to be. 

The propeller can be thought of as a spinning wing with a bit of a twist. The twist(pitch) creates high and low pressure on each side of the blade allowing for thrust to be created. Originally propellers were fixed, meaning the propeller had only one pitch setting available. As the propeller was further developed, adjustable pitch propellers were introduced.  As of today, there is a multitude of options in propellers with variating pitch.

Lateral axis pitch can be thought of as a screw into a wall. The varying pitch would be based on the rotation you spin the screw. For a propeller, the variable pitch allows for greater performance because the propeller is able to adjust its pitch to varying wind conditions, desired airspeed, and even reverse thrust, which is used on larger aircraft when landing. Adjustable pitch propellers include ground adjustment, two-position, full feathering, controlled pitch adjustment, and automatic pitch adjustment (constant speed). Full feathering is an added safety feature in which the pitch can be adjusted to align with the wind to produce minimal drag. The pitch can be changed by the use of hydraulics or an electric pitch mechanism controlled by a governor.   

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