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Topic Review
Applications of Unmanned Aerial Vehicles
Unmanned aerial vehicles (UAVs), also known as drones, have come in a great diversity of several applications such as military, construction, image and video mapping, medical, search and rescue, parcel delivery, hidden area exploration, oil rigs and power line monitoring, precision farming, wireless communication and aerial surveillance. The drone industry has been getting significant attention as a model of manufacturing, service and delivery convergence, introducing synergy with the coexistence of different emerging domains. 
  • 23.7K
  • 27 Jul 2022
Topic Review
Katyusha Rocket Launcher
The Katyusha multiple rocket launcher (Russian: Катю́ша) is a type of rocket artillery first built and fielded by the Soviet Union in World War II. Multiple rocket launchers such as these deliver explosives to a target area more quickly than conventional artillery, but with lower accuracy and requiring a longer time to reload. They are fragile compared to artillery guns, but are inexpensive, easy to produce, and usable on any chassis. The Katyushas of World War II, the first self-propelled artillery mass-produced by the Soviet Union, were usually mounted on ordinary trucks. This mobility gave the Katyusha, and other self-propelled artillery, another advantage: being able to deliver a large blow all at once, and then move before being located and attacked with counter-battery fire. Katyusha weapons of World War II included the BM-13 launcher, light BM-8, and heavy BM-31. Today, the nickname is also applied to newer truck-mounted post-Soviet – in addition to non-Soviet – multiple rocket launchers, notably the common BM-21 Grad and its derivatives.
  • 17.0K
  • 07 Nov 2022
Topic Review
List of Space Shuttle Landing Sites
Three locations in the United States were used as landing sites for the Space Shuttle system. Each site included runways of sufficient length to provide adequate distance for the slowing-down of a returning spacecraft. The prime landing site was the Shuttle Landing Facility at the Kennedy Space Center in Florida, a purpose-built landing strip. Landings also occurred at Edwards Air Force Base in California, and one took place at White Sands Space Harbor in New Mexico. No space shuttle landed on a dry lakebed runway after 1991. The first international site was Cartago, Valle in Colombia (CTA). Various international landing sites were also available in the event of a Transoceanic Abort Landing (TAL) scenario, as well as other sites in the United States and Canada in case of an East Coast Abort Landing (ECAL) situation. Space shuttle landings were intended to regularly take place at Vandenberg Air Force Base in California for Department of Defense missions launched from the site, but none occurred due to the cancellation of all launches from Vandenberg.
  • 11.1K
  • 02 Nov 2022
Topic Review
List of Seaplanes and Amphibious Aircraft
The following is a list of seaplanes and amphibious aircraft, which includes floatplanes and flying boats, by country of origin. Seaplanes are any aircraft that has the capability of landing on water while amphibious aircraft are equipped with wheels to alight on land, as well as being able to land on the water. Flying boats rely on the fuselage or hull for buoyancy, while floatplanes rely on external pontoons or floats. Some experimental aircraft used specially designed skis to skim across the water but did not always have a corresponding ability to float. This list does not include ekranoplans, 'Wing-In-Ground-effect' (WIG), water-skimmers, wingships or similar vehicles reliant on ground effect.
  • 7.5K
  • 07 Nov 2022
Topic Review
Dihedral (Aeronautics)
In aeronautics, dihedral is the angle between the left and right wings (or tail surfaces) of an aircraft. "Dihedral" is also used to describe the effect of sideslip on the rolling of the aircraft. Dihedral angle is the upward angle from horizontal of the wings or tailplane of a fixed-wing aircraft. "Anhedral angle" is the name given to negative dihedral angle, that is, when there is a downward angle from horizontal of the wings or tailplane of a fixed-wing aircraft. Dihedral angle has a strong influence on dihedral effect, which is named after it. Dihedral effect is the amount of roll moment produced in proportion to the amount of sideslip. Dihedral effect is a critical factor in the stability of an aircraft about the roll axis (the spiral mode). It is also pertinent to the nature of an aircraft's Dutch roll oscillation and to maneuverability about the roll axis. Longitudinal dihedral is a comparatively obscure term related to the pitch axis of an airplane. It is the angle between the zero-lift axis of the wing and the zero-lift axis of the horizontal tail. Longitudinal dihedral can influence the nature of controllability about the pitch axis and the nature of an aircraft's phugoid-mode oscillation. When the term "dihedral" (of an aircraft) is used by itself it is usually intended to mean "dihedral angle". However, context may otherwise indicate that "dihedral effect" is the intended meaning.
  • 6.1K
  • 27 Oct 2022
Topic Review
M79 Grenade Launcher
The M79 grenade launcher is a single-shot, shoulder-fired, break-action grenade launcher that fires a 40×46mm grenade, which uses what the US Army calls the High-Low Propulsion System to keep recoil forces low, and first appeared during the Vietnam War. Because of its distinctive report, it has earned the nicknames of "Thumper", "Thump-Gun", "Bloop Tube", "Big Ed", and "Blooper" among American soldiers as well as "Can Cannon" in reference to the grenade size; Australian units referred to it as the "Wombat Gun". The M79 can fire a wide variety of 40 mm rounds, including explosive, anti-personnel, smoke, buckshot, flechette (pointed steel projectiles with a vaned tail for stable flight), and illumination. While largely replaced by the M203, the M79 has remained in service in many units worldwide in niche roles.
  • 5.6K
  • 08 Oct 2022
Topic Review
Xian JH-7
The Xian JH-7 (Jianjiji Hongzhaji – fighter-bomber; NATO reporting name Flounder), also known as the FBC-1 (Fighter/Bomber China-1) Flying Leopard, is a tandem two-seat, twin-engine fighter-bomber in service with the People's Liberation Army Naval Air Force (PLANAF), and the People's Liberation Army Air Force (PLAAF). The main contractors are Xi'an Aircraft Industrial Corporation (XAC) and the 603rd Aircraft Design Institute (later named the First Aircraft Institute of AVIC-I). The first JH-7s were delivered to the PLANAF in the mid-1990s for evaluation, with the improved JH-7A entering service in 2004.
  • 5.5K
  • 22 Nov 2022
Topic Review
Triply Periodic Minimal Surfaces Thermal Hydraulic Effects
Triply Periodic Minimal Surfaces (TPMS) are a kind of periodic implicit surface with zero mean curvature, that is, the surfaces that locally minimize surface area for a given boundary. The TPMS is composed of infinite, non-self-intersecting, periodic surfaces in three principal directions. The TPMS networks as repeated lattice structures have attracted much research interest because they have shown better mechanical performance, mass transfer, and thermal conductivity than conventional and strut-based structures, which have been employed in different disciplines. With excellent performances in the TPMS architectures, current works have investigated the TPMS structures to utilize in a wide range of applications.
  • 5.2K
  • 29 Dec 2022
Topic Review
Examination of Apollo Moon Photographs
The examination of Apollo Moon photographs is an endeavour undertaken by certain people engaged in the debate as to the merits of Moon landing conspiracy theories, despite the abundance of third-party evidence for Apollo Moon landings. A number of allegations and refutations with a variable degree of notability are put forward due to this examination.
  • 5.0K
  • 02 Dec 2022
Topic Review
Space Shuttle Main Engine
The Aerojet Rocketdyne RS-25, otherwise known as the Space Shuttle main engine (SSME), is a liquid-fuel cryogenic rocket engine that was used on NASA's Space Shuttle and is planned to be used on its successor, the Space Launch System. Designed and manufactured in the United States by Rocketdyne (later known as Pratt & Whitney Rocketdyne and Aerojet Rocketdyne), the RS-25 burns cryogenic liquid hydrogen and liquid oxygen propellants, with each engine producing 1,859 kN (418,000 lbf) of thrust at liftoff. Although the RS-25 can trace its heritage back to the 1960s, concerted development of the engine began in the 1970s, with the first flight, STS-1, occurring on April 12, 1981. The RS-25 has undergone several upgrades over its operational history to improve the engine's reliability, safety, and maintenance load. Subsequently, the RS-25D is the most efficient liquid fuel rocket engine currently in use. The engine produces a specific impulse (Isp) of 452 seconds (4.43 km/s) in a vacuum, or 366 seconds (3.59 km/s) at sea level, has a mass of approximately 3.5 tonnes (7,700 pounds), and is capable of throttling between 67% and 109% of its rated power level in one-percent increments. The RS-25 operates at temperatures ranging from −253 °C (−423 °F) to 3300 °C (6000 °F). The Space Shuttle used a cluster of three RS-25 engines mounted in the stern structure of the orbiter, with fuel being drawn from the external tank. The engines were used for propulsion during the entirety of the spacecraft's ascent, with additional thrust being provided by two solid rocket boosters and the orbiter's two AJ-10 orbital maneuvering system engines. Following each flight, the RS-25 engines were removed from the orbiter, inspected, and refurbished before being reused on another mission.
  • 4.6K
  • 24 Oct 2022
Topic Review
Atmospheric Reentry
Atmospheric reentry is the process by which vehicles that are outside the atmosphere of a planet can enter that atmosphere and reach the planetary surface intact. Vehicles that undergo this process include spacecraft from orbit, as well as suborbital ICBM reentry vehicles. Typically this process requires special methods to protect against aerodynamic heating. Various advanced technologies have been developed to enable atmospheric reentry and flight at extreme velocities.
  • 4.1K
  • 01 Dec 2022
Topic Review
China Lake Grenade Launcher
The China Lake Model (or China Lake pump-action grenade launcher) is a pump-action grenade launcher that was developed by the Special Projects Division of the Naval Air Weapons Station (NAWS), which provided equipment to United States Navy SEALs.
  • 3.7K
  • 18 Nov 2022
Topic Review
CubeSat Missions and Their Antenna Designs
CubeSats are a class of miniaturized satellites that have become increasingly popular in academia and among hobbyists due to their short development time and low fabrication cost. Their compact size, lightweight characteristics, and ability to form a swarm enables them to communicate directly with one another to inspire new ideas on space exploration, space-based measurements, and implementation of the latest technology. CubeSat missions require specific antenna designs in order to achieve optimal performance and ensure mission success. Over the past, a plethora of antenna designs have been proposed and implemented on CubeSat missions. Several challenges arise when designing CubeSat antennas such as gain, polarization, frequency selection, pointing accuracy, coverage, and deployment mechanisms.
  • 3.7K
  • 18 Jul 2022
Topic Review
Hongdu L-15
The Hongdu L-15 Falcon (猎鹰) is a supersonic advanced training and light combat aircraft being developed by Nanchang-based Hongdu Aviation Industry Corporation (HAIC) to meet the Chinese People's Liberation Army Air Force (PLAAF) and People's Liberation Army Naval Air Force (PLANAF) lead-in fighter trainer (LIFT) requirements, as well as next-generation training and light combat needs for foreign customers.
  • 3.5K
  • 28 Nov 2022
Topic Review
Lattice Materials
Lattice material is a cellular material consisting of a periodic network of structural elements such as rods or beams. This network of lattices exists over a wide spectrum of scale from the nanoscale to macroscale and has been applied in a wide area of applications. In the nanoscale spectrum, most of the CNT (Carbon Nano Tube) based sensors are made using lattice materials. Micro-lattices material is being developed intensively as it offers high energy absorption capability. On a macroscale, due to its high stiffness and lightweight properties, lattice materials are widely used in aerospace applications.
  • 3.5K
  • 28 Mar 2022
Topic Review
Introduction to Nanofluids
Due to the combination of thermal engineering and the rapid rise of nanotechnology research over the past two decades, novel heat transfer fluids known as “nanofluids” have emerged. A “nanofluid” is a heat transfer fluid that has 1–100 nm-sized “nanoparticles”, which are suspended nanoparticles, scattered throughout the base fluid. To increase the stability of the working fluid, it is crucial to make sure the nanoparticle size is smaller than 100 nm. Water, oils, organic liquids (such as tri-ethylene-glycols, ethylene and refrigerants) and bio-fluids polymeric solutions are the most often utilized base fluids. Numerous studies throughout the years have documented diverse nanofluid preparation methods with various nanoparticle types and their heat transfer capabilities, in addition to advancing the information about nanofluids.
  • 3.4K
  • 13 Dec 2022
Topic Review
Satellite Sandwich Structures
Sandwich panels are widely used in the design of unmanned satellites and, in addition to having a structural function, can often serve as shielding, protecting the satellites’ equipment from hypervelocity impacts (HVI) of orbital debris and micrometeoroids.
  • 3.3K
  • 12 May 2021
Topic Review
List of SpaceX Starship Launches
Prototypes of the upper stage of the SpaceX Starship have been flown nine times.[lower-alpha 1] Designed and operated by private manufacturer SpaceX, the flown prototypes of Starship have been Starhopper, SN5, SN6, SN8, SN9, SN10, SN11, and SN15. Starship is planned to be a fully-reusable two-stage super heavy-lift launch vehicle and unusual for previous launch vehicle and spacecraft designs, the upper stage of Starship is intended to function both as a second stage to reach orbital velocity on launches from Earth, and also eventually be used in outer space as an on-orbit long-duration spacecraft. It is being designed to take people to Mars and beyond into the Solar System.
  • 2.9K
  • 20 Oct 2022
Topic Review
Micro-Electromechanical Systems Vibrating Gyroscopes
Micro-electromechanical systems (MEMS) vibrating gyroscopes have gained a lot of attention because of their low power consumption, easy integration, and low fabrication cost. The usage of the gyroscope equipped with an inertial measurement unit has increased tremendously, with applications ranging from household devices to smart electronics to military equipment. However, reliability issues are still a concern when operating this inertial sensor in harsh environments, such as to control the movement and alignment of mini-satellites in space, tracking firefighters at an elevated temperature, and assisting aircraft navigation in gusty turbulent air. 
  • 2.8K
  • 18 Oct 2022
Topic Review
SpaceX Rocket Engines
Since the founding of SpaceX in 2002, the company has developed four families of rocket engines — Merlin, Kestrel, Draco and SuperDraco — and is currently developing another rocket engine: Raptor.
  • 2.7K
  • 17 Oct 2022
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