Over the course of aviation history, many different types of airplane propellers have been used in piston engine-driven aircraft, as advances in materials and engineering opened up greater and greater possibilities in the aircraft propeller's design and engine performance. In this blog, we will explore some of the different types of propellers used over the years.

The first propellers were fixed-pitch, meaning they could not be adjusted in their mountings on the propeller hub, and were made of wood. They were not carved from a single piece, but built layer by layer with specially prepared wood, with black walnut, sugar maple, yellow birch, and black cherry being the most commonly used. Today however, they have been all but supplanted and are typically only seen on historical examples.

Metal fixed-pitch propellers were first invented in the 1940s. Made from aluminum alloy, they were specially treated to be less prone to warping in extreme heat or cold. Today, almost all propellers, including the types on this list, are made from metal so that the propeller lifespan is increased.

Ground-adjustable propellers can have their pitch (the angle the blades are facing) changed, but only when the propeller is not turning. A clamping mechanism holds the propeller blades in place, and the blade’s angle can be changed by loosening this mechanism. There is no way to change the blade’s pitch mid-flight however, so ground-adjustable propellers are not used in modern aircraft.

Controllable pitch propellers can alter the blade’s pitch during flight, while the propeller is still running. This means that the blade angle can be altered to adapt to changing flight conditions. The number of pitch positions is limited and can be adjusted between minimum and maximum pitch settings.

Constant speed propellers accelerate when the airplane dives and slow down when the aircraft climbs due to the changing load on the engine. This is accomplished by the propeller governor, which senses the aircraft’s speed and changes the blade angle to maintain a specific RPM regardless of the aircraft’s operational conditions. This lets the pilot keep the engine speed constant, which lets the pilot focus on other flight conditions.

Feathering propellers are used with multi-engine aircraft. If one or more aircraft engine parts fail, these propellers reduce propeller drag to a minimum. Feathering propellers can change the blade angle of a propeller to 90 degrees and are usually feathered when the engine of the aircraft fails to generate the power needed to turn the propeller. By rotating to an angle parallel to the line of flight, drag is greatly reduced on the aircraft, allowing it to function as a glider.

Lastly, reverse-pitch propellers are controllable aircraft propellers whose blade angles may be changed to a negative value in-flight. The purpose of a reversible pitch is to create a negative blade angle to produce thrust in the opposite direction, which is done to reduce airspeed during landings and take pressure off the brakes.

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Aircraft powered by piston and turboprop engines feature propeller blades that pull or push on the air around the aircraft to provide propulsion. As piston engines have become more powerful, they require more and more propeller blades.

To understand why, we need to understand the working principle of a propeller. The purpose of a propeller is to “absorb” the power produced by the engine and transmit that power to the air passing through the propeller, which generates the thrust force that propels the aircraft through the air. Therefore, if the propeller and engine are not properly matched based on the power of the engine, the system is inefficient.         

As engine power increases, the designer has several different options to design an aircraft propeller that can efficiently absorb that power. However, most of these options have severe drawbacks.

  1.  Increasing the blade angle (or pitch) of the propeller blades allows them to impart more energy to the airflow but altering the blade angle damages the aerodynamic efficiency of the blade.
  2. Increasing propeller length lets the propeller blades impart more energy by affecting a larger volume of air but forces the designer to extend the landing gear as well to keep the prop blades from touching the ground. This in turn forces the landing gear to extend, which causes a domino effect of other structural and weight issues.
  3. Increasing the revolutions per minute of the propeller is an option, but at a certain speed the propeller blades begin to reach supersonic speeds, causing sonic booms at their tips which drastically increases drag.
  4. The camber (or curvature) of the blades can be altered to change their airfoil and generate more thrust. However, this alters the aerodynamic efficiency much like changing the blade angle and can also cause structural issues with the blades, negatively affecting the lifespan of a propeller.

Therefore, there are two viable options for increasing a propeller’s output. Either you can increase the blade’s width, or chord, or increase the number of blades on the propeller. Increasing the blade chord is easier, but once again, changing the chord affects the aircraft’s aerodynamic efficiency. Thus, this leaves us with the last option, increasing the number of aircraft propeller blades. By doing so, you increase the solidity of the propeller disk, the space that the propeller rotates in. By increasing the solidity, the propeller can transfer more power to the air, thus increasing thrust.

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Unlike early aircraft— which merely required a rough surface to land—  modern aircraft are required to have a fully functioning braking system to ensure a safe and full stop. The basic function of an aircraft brake part is to slow and stop the plane on the tarmac. Just as you push down the brake in an automatic car to stop it from moving forward at a red light, the brakes on an aircraft also allow a pilot to hold the plane on the tarmac before take-off or during taxi.

Brakes function using a basic principle of creating heat energy by interrupting the kinetic energy of the plane in motion. When a moving part comes into contact with a stationary object, friction is created. The friction often results in heat energy being released. Depending on the size and type of the aircraft, the brake cylinder can consist of multiple brake pads and rotating disks, or a single rotating disk with one stationary caliper.

In a common brake system, the pilot is able to push or activate a hydraulic or mechanical system that, in turn, applies pressure on the brakes. A pilot will have two separate pedals or rudders that control the left and right brake. In light aircraft, a simple brake mechanism is efficient enough to safely stop and land the plane. When the pilot activates the mechanical system, the single disc brake, consisting of one rotating element, is slowed down by a light squeezing on each side in the form of a fixed stationary caliper. While this type of aviation braking system is sufficient with a light aircraft with a light load, it is not suitable for larger commercial or military aircraft.

The type and function of the aircraft should be considered when fitting the brake system. Certain braking systems are more adept at converting kinetic energy into heat energy, but struggle to dissipate the heat. Vice versa, some braking systems struggle to convert energy, but can efficiently disperse off the heat.

The larger the plane, the more friction is needed to ground it. The large amount of heat that is generated in the braking process can be dangerous and therefore problematic for aircraft manufacturers. The braking system of an aircraft could be damaged if the heat is not correctly spread out across the system. Aircrafts employ different types of cooling methods to spread and disperse off the heat generated. Segmented rotor brake systems were developed to overcome the issue of the large amounts of heat generated in the slowing process. The segmented rotor brake system consists of a series of multiple rotating plates that are sandwiched between stationary brake pads. As the brake pads touch the rotating disks, they briefly interrupt the rotation, converting the kinetic energy to heat. The segmented brakes are designed with spaces in between each brake pad and disc to allow the excess heat to escape.

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The propeller of an aircraft is a crucial component that contributes to flight. A propeller provides the thrust needed to maintain a forward direction. It maintains a rotary motion in which it creates a difference in air pressure between the front and back surfaces of its blades. The shape of the blade contributes to the pressure difference and air displacement. The rotary motion allows the blades to do their job. Most propellers require an engines assistance to spin.

There are several things to consider when operating an aircraft with a propeller. First off is the angle of attack. This is the angle a wing is positioned in oncoming airflow. The pitch angle is also something to consider. This refers to the angle a propeller blade produces with its rotational plane. A controllable-pitch propeller allows the pilot to manually alter the pitch of the blades during flight, enabling it to have peak performance. The design of the propeller can seriously impact the aircraft engine's performance. A combination of the proper angle of attack and pitch angle results in an exceptionally smooth flight.

Prolonging the longevity of your aircraft propeller can be achieved with proper maintenance, preflight inspections, and routine servicing. If a pilot is able to notice an issue early on, they can circumvent a hefty repair bill later. One tip is to clean the aircraft propeller post flight to ensure that any buildup will not cause corrosion, which can lead to damage. Also, apply oil daily if it is stationed in a salty coastal environment. Internal corrosion is a leading cause of major malfunctions in propellers.

Every single propeller has a recommended overhaul interval based on total flight hours and calendar time that has surpassed. Service is needed after approximately 2,000 flight hours or every 5 years for aircrafts that don’t fly regularly. If your engine needs repair before your propeller does, it can be advantageous to replace both at the same time.

Regular balance checks on your propeller can also help increase the life of your aircraft engine, save costs in repairs, and improve the overall performance of the aircraft. Anytime you replace or remove your propeller you should have it dynamically balanced. Another sign that a balance is needed is if your plane vibrates excessively. Keep in mind that having your propeller balanced will not help disguise other engine issues.

Replacing your propeller with a new one results in improved takeoff and climb, quieter flights, a gain in ground clearance, and a much more satisfactory experience.

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The propeller system is the earliest thrust generator designed for fully powered aircraft flight. Though they have evolved quite a bit since their first operation by the Wright brothers in 1903, propellers utilize essentially the same principles of motion. Let’s take a look at how they work.

At its most fundamental level, an aircraft propeller blade needs to generate thrust to create upward and forward motion. As a whole, it is a device with twisted blades that are pointed at an angle and extend from a hub that is rotated via the power of an engine or motor.  A propeller blade has the capacity to create lift by altering the direction of air that comes into contact with it. This process is representative of Newton’s third law of motion or law of action and reaction. The force of air flow applied to a propeller blade has the potential to create levels of both drag and lift. Lift, by definition, acts perpendicular to the motion of a fluid. Drag applies force in the same direction as fluid movement.

Manipulation of airflow depends on the conservation of momentum, mass, and energy within the propeller system. Air moves as a fluid— it has the ability to redistribute its mass freely while conserving momentum and energy. When airflow interacts with a propeller blade, any change in velocity in one direction can cause a change in velocity in a perpendicular direction.

Propeller blades need to create uniform lift across their length. However, a propeller blade rotates at a lower speed near its hub, and at a higher speed at its tips. This means that the blade tips are traveling a greater distance in the same amount of time as the blade root. The blade must, therefore, account for the difference in speed by incorporating different angles of attack. Propeller blades are designed with a “twist”— they integrate a low angle near their fast-moving tip, and a high angle of attack at the root, ensuring that lift occurs evenly regardless of RPM. The design of the propeller blades have a significant impact on the performance of the aircraft engine. Pitch helps adjust the angle of attack along the propeller blade. It is steeper where a blade is moving more slowly (near the hub) and shallow where a blade is moving faster (tip), allowing for differing angles of attack along the length of the blade.

In order to accelerate air downward to create lift, each propeller blade is shaped like an airfoil. Aerofoil stall, or loss of lift, is prevented by the shape of the blade itself. A propeller blade is usually cambered, just like an airfoil wing. Camber, in this instance, refers to the characteristics of the curve of an airfoil's upper and lower surfaces around the blade and the difference in pressure between the two. A pilot, or engineer, can increase the lifespan of a propeller by regular maintainence.

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 "If I told you half the things I've heard about this Jabba the Hutt, you'd probably short circuit." Since you’re here, these words said to R2D2 in the film Return of the Jedi are probably not the first time you’ve heard of a short circuit. A short circuit is one of the many issues electronic and electrical protection devices are designed to prevent. 

Let’s talk basics. A protection device simply has two main functions: consistency in regulation, and protection of electrical and electronic circuits. At their most basic, circuit protection devices redirect a power supply into a separate circuit, using overcurrent protection. This allows the device to prevent damage to an existing circuit from excessive voltages and currents. Protection devices also may serve as a safeguard to remove the risk of fire hazard and electrocution. Now that we’re caught up on what exactly a protection device is, let’s cover the most common designs that you might come across and when you might encounter them.

1. Circuit Breaker

  • What is it?
    • Electrical switch
    • Stops a current when there is excess voltage, or when a system failure occurs
  • When is it used?
  • Utilized to protect against an electrical short circuit
    • Useful on both high current and low current circuits 


  • What is it?
    • Electronic device
    • Metal strip that has the capability to liquify when current flow is too high
    • Categorized by intended application, response time, and breaking
    • When is it used?
    • In systems where protection is needed without a large disruption

3.  Poly Switch (Multifuse/Polyfuse)

  • What is it?
    • Passive electrical device
    • Protects from over current errors
    • Operates as a resettable fuse
  • When is it used?
    • Commonly used on mechanical transforms, computer power supplies, and nuclear or aerospace applications

4.   Residual Current Circuit Breaker (RCCB/RCD)

  • What is it?
    • Electronic device
    • Testable & resettable
    • Shut-off capability - will identify an issue in power supply, and shut off within a short period
    • Does not protect against overload of a circuit
  • When is it used?
    • Home power supply

5.   Surge Protection Device

  • What is it?
    • Electrical device
    • Most common protection unit for over-voltage protection
    • Well organized mechanism
    • Can be used in most stages of a system
  • When is it used?
    • Electrical fitting security systems

6. Metal Oxide Variable Resistor/Voltage Dependent Resistor (VDR)

  • What is it?
    • Electronic device
    • Resistance varies based on incoming voltage
  • When is it used?
    • Applicable with electrical circuits that are vulnerable to electrostatic discharge and/or lighting

7. Gas Discharge Tube/Expulsion Lamps

  • What is it?
    • Electrical device
    • Gas filled tube - electrodes are contained within the gas, and held in an insulated, temperature resistant capsule
    • Able to ionize gas using incoming voltage

  • When is it used?
    • Switching device for electrical protection
    • Lightning protection

8. Inrush Current Limiter

  • What is it?
    • Electrical device
    • Stops inrush current before it reaches circuit breakers and fuses to reduce potential damage
    • High resistance capability
    • Heat protection allows flow of current on a regular basis
    • When is it used?
    • Fixed resistors
    • NTC Thermistors

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Heat exchangers are used to transfer heat from one source to another. Thermal energy is transferred from one source to another without water and gas coming into contact with each other. These heat exchangers are commonly used in a variety of aircraft components. In aviation, flat tube and plate-fin heat exchangers are the most commonly used in aviation. These components must be properly cleaned in order to function smoothly.

Because they will be used at high altitudes, temperature, air density, and pressure resistance all need to be taken into consideration. The fan component used in the heat exchanger must also be carefully selected since more airflow is required to remove heat in higher altitudes where air density is much lower.

Liquid cooling tends to perform better than air cooling alone. Liquid cooling is also quieter and less vulnerable to the problems associated with high altitudes. It requires less power and weighs less because there is no need for a large fan or wide spacing.

Plate-fin heat exchangers use plates and finned chambers in order to transfer heat. They can be used for air-to-air, air-to-liquid, or liquid-to-liquid cooling. Considering their weight, this type of heat exchanger part performs very well.

Flat tube heat sink parts consist of several flat tubes that are vacuum-brazed in between. These tend to be less expensive than plate-fin designs.

There are high standards when it comes to cleaning heat exchangers. This is due to all the strict and stringent safety requirements that govern aviation. The amount of buildup can be estimated based on past experiences as well as the number of hours flown.

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One of the most important components to making flying safe is the actuator, a “mover” that uses a control signal and power source in order to move and control a mechanism or system. They play a vital role in flight and control, ensuring safety of the aircraft and passengers. In the case of aircraft actuators, they are used in landing gear, flaps— and, in the military, weapons systems.

Landing gear actuators are used to provide the retraction and extension motion for the landing gear located at the bottom of the fuselage. Originally, airplanes were fitted with hydraulic actuators, however, many companies are beginning to transition to electric actuators for better technology and more reliability. Because these actuators are located very close to the ground while the airplane is moving at high speeds, they have to be able to withstand high-pressure up to at least 5,000 psi and be built very strong to resist damage caused by debris kicked up by the wheels. But, because weight matters, landing gear actuators are usually made from lightweight materials.

Aircraft flap actuators, also known as “flap actuators”, are located on each aircraft wing and used to maintain efficient flight at low airspeeds. They’re mounted with a rotating screw that allows the flap to move up and down accordingly. On larger aircraft, there are retractable flap actuators placed on the outside edge of the wing in order to change the effective surface area of the airfoil and counteract the lack of lift generated at lower airspeeds.

Weapons systems also use linear actuators to ensure reliability. In combat, fighter jets need to be able to consistently open the bay doors to access the weapons. If the doors don’t open, or they jam, they could lose their lives. So, fighter jets use electric and hydraulic actuators equipped with sensors and stop modules to ensure reliability and safe use.

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The most expensive and important part of an aircraft is easily the engine. Sometimes you don’t have any other option than to overhaul your current engine. It can be a frustrating process, but it gets easier when you know who to turn to and what needs to be done.

It’s important, for safety reasons, to regularly inspect and maintain your aircraft engine. Every 1,800 hours for a hot section inspection, and 3,600 for an overhaul. The hot section inspection is when all the hot section aircraft engine components are inspected to ensure that they can generate enough power to fly efficiently and safely. An overhaul is when the entire engine is disassembled, cleaned, inspected, reassembled, tested, and shipped back to the installation agency.

Overhauls are a thorough process. The engine’s four major sections, accessory gearbox, gas generator section, power section, and reduction gearbox, have to be disassembled and properly inspected. All the fuel control units, fuel pumps, nozzles, flow dividers, fuel oil heaters, speed governors, heated tubes, and ignition units need to be overhauled. Engine mounts are changed, and engine hoses are reviewed at this time. Mandatory and optional service bulletins are usually addressed at this time as well.

Because of how much more work an overhaul is, the price can be extremely high. Understanding your aircraft engine parts and what needs you have regarding your engine can help provide you with a better cost-benefit analysis. Sometimes it’s more cost-efficient to just upgrade than to overhaul. However, this also depends on who you’re working with. Are you comfortable with paying a bit more for an authorized and approved service center? Or are you okay with using a cheaper service center that your engine’s OEM does not support?

Choosing the right service center to oversee and do your overhaul is important. Experienced and reliable service centers will walk you through the entire process and help you weigh different costs and benefits, provide you with competitive quotes with options, be willing to answer all your questions, and be able to do any extra work you may need or want done.

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Often now the aircraft safety videos are disregarded. This may be because aircrafts today have become so much safer than ever before and customers do not see the importance of them. The statistics of aircraft fatalities have decreased every year. As a matter of fact, the U.S. had zero aircraft fatalities in 2017. Since airline safety has become very stringent we may think less and less about what to do in case of an emergency some may believe the burden lies on the airline and not the customers. However, it is useful to know how the evacuation process works in the next time you are on your flight.

To start, it is good to know every commercial aircraft has an emergency evacuation slide now. Aircrafts have become much safer as they have become a very prominent mode of transportation as thousands of domestic and international flights, fly every single day. But it is good to know what happens in the case of an emergency.

First off, when the door is closing for take off the pilot speaks over the speaker to the cabin crew saying, “Doors to automatic and cross check”. This means to put the doors in automatic mode. Meaning when you are in an aircraft emergency, the evacuation slide will deploy automatically. Then the opposite is announced when landing “Doors to manual”. In the case of an emergency, slides will deploy automatically as the aircraft doors open, however if they are on the manual setting the slides will not deploy without further actions. The inflation process takes about 6 seconds. The goal is for all passengers must be able to leave the cabin in less than 90 seconds. Most slides can serve as a raft now except on certain aircrafts. The raft is very useful in the case that there is a emergency landing overseas.

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