The Aviation Science

Empennage 🛩️The empennage of an aircraft is also known as the tail section. Most empennage designs consist of a tail cone, fixed aerodynamic surfaces or stabilizers, and movable aerodynamic surfaces. 🛩️The tail cone serves to close and streamline the aft end of most fuselages. The cone is made up of structural members like those of the fuselage; however, cones are usually of lighter construction since they receive less stress than the fuselage. 🛩️The other components of the typical empennage are of heavier construction than the tail cone. These members include fixed surfaces that help stabilize the aircraft and movable surfaces that help to direct an aircraft during flight. The fixed surfaces are the horizontal stabilizer and vertical stabilizer. The movable surfaces are usually a rudder located at the aft edge of the vertical stabilizer and an elevator located at the aft edge the horizontal stabilizer. 🛩️The structure of the stabilizers is very similar to that which ...

Types of Radio Waves 🛩️Radio waves of different frequencies have unique characteristics as they propagate through the atmosphere. VLF, LF, & MF waves have relatively long wavelengths and utilize correspondingly long antennas. 🛩️Radio waves produced at these frequencies ranging from 3kHz to 3mHz are known as ground waves or surface waves. They follow the curvature of the earth as they travel from the broadcast antenna to the receiving antenna. Ground waves are particularly useful for long distance transmissions. Automatic direction finders (ADF) & LORAN navigational aids use these frequencies. ✈️High frequency (HF) radio waves travel in a straight line & do not curve to follow the earth’s surface. This would limit transmissions from the broadcast antenna to receiving antennas only in the line-of-sight of the broadcast antenna except for a unique characteristic. HF radio waves bounce off of the ionosphere layer of the atmosphere. This refraction extends the range of...

Transonic Area Rule 🛩️The Transonic area rule, also called the Whitcomb area rule, is a design technique used to reduce an aircraft's drag at transonic and supersonic speeds, particularly between Mach 0.75 and 1.2. 🛩️This is one of the most important operating speed ranges for commercial and military fixed-wing aircraft today, with transonic acceleration being considered an important performance metric for combat aircraft and necessarily dependent upon transonic drag. 🛩️At high-subsonic flight speeds, the local speed of the airflow can reach the speed of sound where the flow accelerates around the aircraft body and wings. The speed at which this development occurs varies from aircraft to aircraft and is known as the critical Mach number. 🛩️The resulting shock waves formed at these points of sonic flow can result in a sudden increase in drag, called wave drag. To reduce the number and power of these shock waves, an a...

Basic Clouds 🛩️Cloud type is determined by its height, shape, & characteristics. They are classified according to the height of their bases as low, middle, or high clouds, as well as clouds with vertical development. 🛩️Low clouds are those that form near the Earth’s surface and extend up to about 6,500 feet AGL. They are made of water droplets but can include supercooled water droplets that induce hazardous aircraft icing. Typical low clouds are stratus, stratocumulus, nimbostratus. Fog is also low cloud formation. This Clouds create low ceilings, hamper visibility, & can change rapidly. They influence flight planning & can make visual flight rules (VFR) flight impossible. 🛩️Middle clouds form around 6,500 feet AGL & extend up to 20,000 feet AGL. They are composed of water, ice crystals, & supercooled water droplets. Typical middle-level clouds include altostratus & altocumulus. These types of clouds are encountered on cross-country flights at highe...

Wet Sump Oil System ✳️The engine oil system performs several important functions: 🛩️Lubrication of the engine’s moving parts . 🛩️Cooling of the engine by reducing friction . 🛩️Removing heat from the cylinders . 🛩️Carrying away contaminants . 🛩️Providing a seal between the cylinder walls and pistons. ➡️Subscribe us for more aircraft knowledge and aircraft fact⬅️ ➡️Do Share with your Friends⬅️

Airport Markings ➡️Subscribe us for more aircraft knowledge and aircraft fact⬅️ ➡️Do Share with your Friends⬅️

Runway Markings and Signs ➡️Subscribe us for more aircraft knowledge and aircraft fact⬅️ ➡️Do Share with your Friends⬅️

Bleed Air from Engine 🛩️When air enters a turbine engine, it goes through a series of compressors, which significantly increase the air temperature and pressure before mixing that air with fuel and igniting it. A small portion of that compressed air, however, does not enter the combustion chamber and instead is redirected from the engine via valves, ducting and manifolds to various other areas of the aircraft. 🛩️Bleed air is extracted from the compressor of the engine or APU. 🛩️The specific stage of the compressor from which the air is bled varies by engine type. 🛩️In some engines, air may be taken from more than one location for different uses as the temperature and pressure of the air is variable dependant upon the compressor stage at which it is extracted. 🛩️Bleed air from that system can be utilized for internal cooling of the engine, cross-starting another engine, engine and airframe anti-icing, cabin pressurization, pneumatic actuators, air-driv...

Inertial Navigation System 🛩️INSs contain Inertial Measurement Units (IMUs) which have angular and linear accelerometers (for changes in position). 🛩️some IMUs include a gyroscopic element (for maintaining an absolute angular reference). 🛩️Angular accelerometers measure how the vehicle is rotating in space. 🛩️Generally, there is at least one sensor for each of the three axes: pitch (nose up and down), yaw (nose left and right) and roll (clockwise or counter-clockwise from the cockpit). 🛩️Linear accelerometers measure non-gravitational accelerations of the vehicle. 🛩️Since it can move in three axes (up & down, left & right, forward & back), there is a linear accelerometer for each axis. 🛩️A computer continually calculates the vehicle's current position. 🛩️First, for each of the six degrees of freedom, it integrates over time the sensed acceleration, together with an estimate of gravity, to calculate the current velocity. Then it integrates the vel...

Automatic Direction Finder 🛩️ADF (Automatic Direction Finder) is the radio signals in the low to medium frequency band of 190 Khz. to 1750 Khz. 🛩️It has the major advantage over VOR navigation in the reception is not limited to line of sight distance. 🛩️The ADF signals follow the curvature of the earth. 🛩️The maximum of distance is depend on the power of the beacon. 🛩️The ADF can receives on both AM radio station and NDB (Non-Directional Beacon). 🛩️Commercial AM radio stations broadcast on 540 to 1620 Khz. Non-Directional Beacon operate in the frequency band of 190 to 535 Khz. ✈️ADF COMPONENTS ✈️ADF Receiver: pilot can tune the station desired and to select the mode of operation. The signal is received, amplified, and converted to audible voice or morse code transmission and powers the bearing indicator. ✈️Control Box (Digital Readout Type) : Most modern aircraft has this type of control in the cockpit. In this equipment the frequency tuned is displayed as digital...

Non Directional Beacon 🛩️A Non-Directional Beacon is a ground-based, low frequency radio transmitter used as an instrument approach for airports and offshore platforms. 🛩️The NDB transmits an omni-directional signal that is received by the Automatic Direction Finder, a standard instrument onboard aircraft. 🛩️The pilot uses the ADF to determine the direction to the NDB relative to the aircraft. 🛩️To navigate using the ADF, the pilot enters the frequency of the NDB and the compass card (or arrow) on the ADF will indicate the heading to the station. 🛩️The signal is transmitted on an uninterrupted 24/7 basis. 🛩️An audible Morse Code call sign of one or more letters or numbers is used to identify the NDB being received. 🛩️NDB’s used for aviation are standardized by ICAO, Annex 10 which specifies that NDB be operated on a frequency between 190 to 1800 kHz. 🛩️In North America, the frequency range is typically from 190 to 625 kHz, for offshore operation...

Microwave Landing System 🛩️The microwave landing system (MLS) is an all-weather, precision radio guidance system intended to be installed at large airports to assist aircraft in landing, including 'blind landings'. 🛩️MLS enables an approaching aircraft to determine when it's aligned with the destination runway and on the correct glidepath for a safe landing. 🛩️MLS has a number of operational advantages over ILS, including a wider selection of channels to avoid interference with nearby installations, excellent performance in all weather, a small "footprint" at the airports, and wide vertical and horizontal "capture" angles that allowed approaches from wider areas around the airport. 🛩️MLS employs 5 GHz transmitters at the landing place which use passive electronically scanned arrays to send scanning beams towards approaching aircraft. 🛩️An aircraft that enters the scanned volume uses a special receiver that calculates its positi...

Electronic Flight Instrument System 🛩️ An electronic flight instrument system (EFIS) is an electronic display technology on the flight deck display system. 🛩️It usually consists of Engine Indicating and Crew Alerting System (EICAS), Primary Flight Display (PFD) and Multi-Function Display (MFD) display. 🛩️They commonly use a liquid crystal display (LCD) even though they earlier used cathode ray tube (CRT) displays. 🛩️Installation of the EFIS varies greatly this is where a wide-body aircraft is equipped with six or more display units on which flight and navigation data are displayed while a light aircraft is likely to have one unit. ✈️The installation of EFIS follows the sequence ✈️ Displays ✈️Controls ✈️ Data processors 🛩️Basic EFIS contains all the facilities in one unit.... ✈️Display Units- 🛫Primary flight display (PFD) 🛫Navigation display (ND) 🛫Multi-function display (MFD) 🛫Electronic centralized aircraft monitoring (ECAM)/Engine indicatio...

Hydraulic System 🛩️There are multiple applications for hydraulic use in aircraft depending on the complexity of the aircraft. For example, a hydraulic system is often used on small airplanes to operate wheel brakes, retractable landing gear, and some constant speed propellers 🛩️On large airplanes, a hydraulic system is used for flight control surfaces, wing flaps, spoilers, and  other systems 🛩️A basic hydraulic system consists of a reservoir, pump (either hand, electric or engine-driven), a filter to keep the fluid clean, a selector valve to control the direction of flow, a relief valve to relieve excess pressure, and an actuator 🛩️The hydraulic fluid is pumped through the system to an actuator or servo. A servo is a cylinder with a piston inside that turns fluid power into work and creates the power needed to move an aircraft system or flight control. Servos can be either single-acting or double-acting, based on the needs of the system. This means that the fluid ...

🛩️Krueger flaps are lift enhancement devices that are fitted to the leading edge of an aircraft wing. 🛩️Unlike slats or drooped leading edges, the main wing upper surface and its nose is not changed. Instead, a portion of the lower wing is rotated out in front of the main wing leading edge. 🛩️Current Boeing aircraft, and many others, use this design between the fuselage and closest engine, where the wing is thickest. Outboard of the engine, slat flaps are used on the leading edge. The Boeing 727 also used a mix of inboard Krueger flaps and outboard slats, although it had no engine between them. 🛩️Most early jet airliners, such as the Boeing 707 and Boeing 747, used Krueger flaps only. 🛩️The aerodynamic effect of Krueger flaps may be similar to that of slats or slots (in those cases where there is a gap or slot between the flap trailing edge and wing leading edge), they are deployed differently. 🛩️Krueger flaps, hinged at their foremost position that...

🛩️A combustor is a component or area of a gas turbine, ramjet, or scramjet engine where combustion takes place. It is also known as a burner, combustion chamber or flame holder. In a gas turbine engine, combustion chamber is fed high pressure air by the compression system. 🛩️The combustor then heats this air at constant pressure. After heating, air passes from the combustor through the nozzle guide vanes to the turbine. In the case of a ramjet or scramjet engines, the air is directly fed to the nozzle. 𝐀𝐧𝐧𝐮𝐥𝐚𝐫 𝐓𝐲𝐩𝐞 ✈️The most commonly used type of combustor is the fully annular combustor. Annular combustors do away with the separate combustion zones and simply have a continuous liner and casing in a ring. There are many advantages to annular combustors, including more uniform combustion, shorter size, lighter, and less surface area. Annular combustors tend to have very uniform exit temperatures. They also have the lowest pressure drop of the three...

🛩️The CAT gauge indicates the temperature of the air before it enters the carburetor. The temperature reading is sensed by a bulb or electric sensor. In the test cell, the sensor is located in the air intake passage to the engine and, in an aircraft it is located in the ram-air intake duct. The CAT gauge is calibrated in the centigrade scale. This gauge, like many other multi-engine aircraft instruments, is a dual gauge; two gauges, each with a separate pointer and scale, are used in the same case. 🛩️The yellow arc indicates a range from –10 °C to +15 °C, since the danger of icing occurs between these temperatures. The green range indicates the normal operating range from +15 °C to +40 °C. The red line indicates the maximum operating temperature of 40 °C; any operation at a temperature over this value places the engine in danger of detonation. ➡️Subscribe us for more aircraft knowledge and aircraft fact⬅️ ➡️Do Share with your Friends⬅️