Like all powered aircraft, helicopters operate on the principles of lift and thrust. Lift is the force that pushes the aircraft up into the sky, and thrust is the force that propels the aircraft forward. In a fixed wing aircraft, like a conventional passenger jet, lift is provided by the wings, and thrust is provided by the engines. In a helicopter however, both lift and thrust are generated by the helicopter’s main rotor.

The main rotor, mounted horizontally above the aircraft’s fuselage, is arguably the most important part of the helicopter. The main rotor provides the lift and thrust that allows the helicopter to fly, as well as move laterally, make turns, and change altitude. The main rotor is powered by a crankshaft connected to the engine. Key to controlling the main rotor is the swash plate assembly, which consists of two parts, the upper and lower swash plate. The upper swash plate connects to the mast, or rotor shaft, through linkages, and the blade grips, which connect the blades to a hub at the center of the rotor. A nut called the Jesus nut mounts the hub on the helicopter’s mast, and control rods from the upper swash plate connect to the blades. These control rods transfer movements in the upper swash plate to the blades.

Meanwhile, the lower swash plate is fixed, and doesn’t rotate. Between the upper and lower swash plates is a set of ball bearings, and allows the upper plate to spin freely on top of the lower plate. Control rods attach to the lower swash plate, and are connected to the pilot’s controls in the cockpit. Therefore, when the pilot operates the controls, their inputs are transmitted via the control rods to the lower swash plate, to the upper swash plate, then to the control rods that connect to the blades, thus affecting the blades, changing their airfoil, and steering the helicopter.

However, the main rotor spinning generates an enormous amount of torque that, if left unchecked, would cause the helicopter to spin uncontrollably and make it impossible to fly. Russian-born engineer Igor Sikorsky overcame this problem by adding a tail rotor to his design, which would be emulated by the vast majority of over helicopter designs. A tail rotor is a vertically-mounted rotor in the tail of the aircraft, which spins in opposition of the torque generated by the main rotor. This effectively negates the main rotor’s torque, balances the helicopter, and allows it to fly in a controllable manner.

At Paragon Purchasing, owned and operated by ASAP Semiconductor, we can help you find all the helicopter parts for the aerospace, civil aviation, and defense industries. For a quick and competitive quote, email us at sales@paragonpurchasing.com or call us at 1-914-359-2001.


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Every light on an aircraft has its own purpose. They can be broken down into two categories based on what it makes visible, either aircraft or pilot visibility. Lights that improve aircraft visibility are lighting systems that help make the aircraft more visible to other aircraft while in flight. Lights that improve pilot visibility are lighting systems that make it clearer for the pilot to look out the flight deck windows.

Landing lights typically are the brightest lights that are made specifically to enhance visibility during the plane's descent to land. They also are used to illuminate the runway when airports have a lack of lighting, like a large headlight on a car. They are located on the wing root, in the outboard wing, or for helicopters, somewhere on the front fuselage. Taxi lights are located on the nose landing gear of most planes. Essentially a bright white lamp in the front of the plane is used when the aircraft is in motion or on the ground. Taxi lights are used during taxi, takeoff, and landing, making it a very versatile light. These two lighting systems are under the pilot visibility category.

Lights that increase aircraft visibility are mainly used to improve visibility of the aircraft to other planes in flight. Navigation lights come in different colors: Red beacon lights are located on the left/port wing, green on the right/starboard wing, and white light on the tail help outside observers or other pilots determine what direction the observed plane is flying. There are also lights located on the upper and lower fuselage to also help prevent collisions, referred to as beacon lights. Planes also have strobe lights that flash very bright to draw attention to the aircraft while in flight.

Some other less vital external lights include logo lights, which illuminates the respective company the plane is commissioned under. Runway turnoff lights, located on the leading edge of the wing root, are used to light up the runway during taxi and turning off the runway. Wheel well lights are used primarily to assist ground personnel while making pre-flight inspections when airport lighting is low and are located on the nose and main gear wheel wells.



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The modernization of aircraft has seen a correlated increase in the amount of AC power systems providing the vessel its electrical capabilities. Many of these electrical systems operate solely on AC. On the other hand, lighter aircraft tend to function better when using DC systems. The model AC electrical system would be composed of an AC alternator, a system that regulates the aforementioned alternator, as well as fuses and wiring.

Inverters are capable of bridging the gap when only a small amount of AC power is required. It serves a multi-function purpose, as it can also be used as a reserve power source on specific aircraft that employ an AC alternator. An inverter can also convert DC power into AC power when necessary. Many inverters are capable of supplying both 26-volt AC, as well as 115-volt AC. However, if both voltages are occupied, the power must be distributed on separate 26- and 115-volt AC busses.

AC alternators were designed for use on aircraft that employ a significant amount of electrical power. This includes all commercial and transport aircraft. In case of an emergency, these larger aircraft sport an additional AC power source (either an AC inverter or a small AC alternator). Modern alternators are designed to be exceptionally reliable and facilitate very little maintenance. They utilize a brushless technology that can transfer energy magnetically.

The core components of these AC alternators include three generator stages; each one functioning in different ways to create a harmonious design. The first one is the exciter generator, which is a stationary field composed of a permanent magnet alongside two electromagnets. The second generator is the pilot exciter which is mounted on the stationary part of the assembly. The AC output is supplied to the generator control circuitry where it is regulated, rectified, and later sent to the exciter field windings. The current then provides the voltage required for the last of the three components - the main AC alternator. The rotor continues to turn as the main AC alternator field generates power into the main AC alternator armature, utilizing electromagnetic induction. This final output concludes the three-stage AC process and is what essentially powers the different electrical facets.

This type of technology requires some sort of cooling mechanism. Oil is a common fluid used in successful cooling techniques, which is supplied by the constant speed drive assembly. Ports allow oil-flow between the constant speed drive and the generator. Oil level is critical to the success of the AC alternator.



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Aircraft come equipped with a myriad of lights that are designed to perform different functions. Whether it be navigation, safety, improving visibility, or signaling, the lights on an aircraft are essential to its signaling communications. An aircraft’s external lighting includes navigation lights, anti-collision lights, landing lights, taxi lights, and wing lights.

Navigation lights signal your location and relative direction of travel to other aircraft flying close by. When another pilot sees a green light, they know that the other aircraft is flying in front of them and to the right. A red light also signifies that the other aircraft is located in front of them, but they are flying to the left. If a pilot sees white lights, that signifies being behind the aircraft. Navigation lights must be utilized between sunset and sunrise; during all hours within that window. Poor weather is another condition that requires the pilot to turn on the navigation lights.

Anti-collision lights come in two variations: red beacons and white strobes. These are mandatory to use at night and recommended to use during the day. The red beacon is a warning to other pilots that the engine will soon be activated. High intensity white strobes serve the purpose of increasing a plane’s visibility. These lights can adversely affect another pilot’s vision, so they should only be used when entering and exiting the runway.

Landing lights are used to illuminate runways. These are high powered lights that increase aircraft visibility and improve safety. They typically generate a substantial amount of heat and are easily damaged; using them for prolonged periods of time can shorten their longevity. A commercial pilot typically activates the landing lights upon takeoff and when they are preparing to land (below 10,000 feet).

Taxi lights share a strong similarity to landing lights—minus the power requirement. When a plane is maneuvering through an airport, the taxi lights should always be illuminated. Some smaller planes are constructed with a single landing light, which doubles as a taxi light. Runway turnoff lights support the functions of taxi lights in that they illuminate runway turnoffs. On departure, they’re used for taxiing. On arrival, they’re turned on to supplement the landing lights.

Wing lights are designed to outline the edges of each wing. Some airports require them to be turned on when pilots are entering the runway—for better visibility of the plane. Pilots can also use wing lights to signal other aircraft.


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If you’ve been to an airport at night, you’ve probably noticed the array of vivid, sparkling lights as aircraft glide down the tarmac. The beaming lights on the airframe are an assortment of fixtures that each serve a specific purpose to aircraft and air traffic control. A few light assemblies that are universal to every commercial aircraft include anti-collision lights, taxi lights, and landing lights.

Anti-collision light fixtures (ACLs) give aircraft, and aircraft controllers, the ability to identify another aircraft. There is a red beacon light on top and bottom of the aircraft fuselage, as well as two white strobe lights— one on each wing tip. These lights are turned off when the engine is shut off due to their intensity. In order to be visible at night, ACL lights can be seen from up to 20 miles away and 40,000 ft. from the ground, which means they can be blinding, literally.

Another version of ACLs are colorful position lights; they are the red and green lights on aircraft wing tips. The red light is always located on the left wing, and the green light is always located on the right wing. There is also a white rear-facing light fixture on the back of each wing. This arrangement allows other aircraft to determine whether an airplane is traveling towards them or away from them. Indicator lights are kept on until the aircraft completes its full flight cycle.

Taxi lights serve a similar purpose as the headlights on an automobile do. They are installed on the nose gear strut, as well as each wing. As an aircraft prepares for landing or takeoff, the taxi lights illuminate the tarmac and allow for easier visibility as they navigate to their gate or runway. The lights cover several feet of ground around the aircraft. When preparing to land, most pilots keep taxi lights off until the tower gives them clearance. This helps eliminate confusion about which aircraft have been cleared to land at any given time. Taxi lights are typically only turned on by the pilot when the aircraft is below 18,000 ft.

If you’ve glanced out a passenger window as the aircraft prepares its final descent, you may have seen landing lights pulsing on the wing. Landing lights are mounted underneath an aircraft fuselage or on the wings of an aircraft. Despite their name, they are also used during take-off. The “blinking” alternates, or pulses, from the left of the aircraft to the right of the aircraft in order to increase visibility as it’s descending. These lights are switched to a static state when an aircraft is around 200 ft. from the ground and can fully illuminate the ground below an aircraft from this distance. Landing lights are extremely bright, alike to the intensity of a spotlight. Landing lights utilize 600-watt bulbs— to put this into perspective, they are over 10x as bright as automotive headlights, and can be seen from miles away.

And there you have it— the practical reasons for a majority of the lights on commercial aircraft. They’re useful, but they’re pretty cool looking too.


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