Aerodynamic Forces
When two solid objects interact in a mechanical process, forces are transmitted, or applied, at the point of contact. But when a solid object interacts with a fluid, things are more difficult to describe because the fluid can change its shape. For a solid body immersed in a fluid, the "point of contact" is every point on the surface of the body. The fluid can flow around the body and maintain physical contact at all points. The transmission, or application, of mechanical forces between a solid body and a fluid occurs at every point on the surface of the body. And the transmission occurs through the fluid pressure. Definitions of Lift and Drag Since the fluid is in motion, we can define a flow direction along the motion. The component of the net force perpendicular (or normal) to the flow direction is called the lift; the component of the net force along the flow direction is called the drag. These are definitions. In reality, there is a single, net, integrated force caused by the pressure variations along a body. This aerodynamic force acts through the average location of the pressure variation which is called the center of pressure What is a missile? Basically any object thrown at a target with the aim of hitting it is a missile. Thus, a stone thrown at a bird is a missile. The bird, by using its power of reasoning may evade the missile (the stone) by moving either to the Left, right, top or bottom with respect to the flight path (trajectory) of the missile. Thus, the missile in this case has been ineffective in its objective of hitting the bird (the target). Now, if the stone too is imparted with some intelligence and quick response to move with respect to the bird, to overcome aiming errors and the bird's evasive actions and hit it accurately, the stone now becomes a guided missile. The incorporation of energy source in a missile to provide the required force for its movement (propulsion), intelligence to go in the correct direction (guidance) and effective maneuvering (control) are mainly the technologies of guided missiles. They help in making a missile specific to a target, that is, they determine the size, range and state of motion of a missile. Types Of Guided Missiles
Presently, there are many types of guided missiles. They can be broadly classified on the basis of their features such as type of target; range; mode of launching; system adopted for control, propulsion or guidance; aerodynamics; etc. They are also termed in a broad sense as strategic or tactical, defensive or offensive. On the basis of target they could be called
Year 2100, ISRO, s robotic probe is conducting experiments in keiuper belt outside the solar system. Suddenly the probe detects some unusual signals. Scientists at ISRO confused, they have no idea where did these signals came from. The disturbance in communication between ground station and robotic probe is increasing. All the radar stations are pointed in the direction of the robotic probe. Within matter of minutes Scientists found huge electromagnetic wave patterns. ISRO concluded probably some kind of communication system, but who are they? The whole world turned towards that what they found was shocking news. A fleet of alien crafts rapidly approaching earth, is this is the end of Homo sapiens? The above described scenario is not unlikely. In this vast universe there is all the possibility of an advanced civilization. What we do if that alien civilization attack us. In the present technological advancement is not enough to counter an alien threat. But in the future surely we develop something to counter an alien invasion. Here is a brief idea about countering an alien attack. Every enemy has a weakness we should find out what it is. To repeal an alien attack we need three things. 1)Intelligence: we need to know who they are , what their strength and weakness 2)Defense : we need to reinforce the lines of defense to protect earth 3)Attack strategy : if they do land on earth we need weapons & strategy to counter them THE PLAN
We need an early warning system to detect the aliens. Radars are the best choice for that. We need to monitor the entire solar system; the intruders will come in any direction. But there is a problem the area of solar system is 6*10 26 sq miles. We can’t monitor this much area using the radar systems on the earth. But there is a solution. The outer edge of the solar system is the aur cloud a region of huge comets. We can use those comets as radar stations & can create a network of radar system that can monitor the entire solar system and can monitor the intruders in every direction. Still there is some problems these alien crafts may be stealthy even humans are using stealth aircrafts , ships etc. maybe we can find the larger mother ships but it is not easy to find the tiny alien probes dispatched from the mother ships especially most of the outer space radars using high frequency electromagnetic waves. Hmm we need something else to find the alien ships. To detect the stealth alien ships we can use another frequency called X-rays. X rays are very small i.e.; they are billions of times smaller than the radar signals they can pick up an object in the size of sand X rays are ideal solution for finding alien intruders and also we can create ultra sensitive X ray scanners on board robots and place them in aur clouds & can fly through the comets and scan for tiny alien probes. The following are some of the real pictures of scramjet, tested by the ISRO some months ago mounted on a Rohini Rocket. This is a brief description of scramjet based on these pictures. We are preparing a detailed article about different propulsive devices including scramjet, so followers will get more information about scramjet in the coming days. What is a scramjet?
Scramjet, or Supersonic Combustion Ramjet is a kind of air breathing (It sucks the air from atmosphere) propulsion. In scramjet the combustion taking place at supersonic speeds while in other air breathing propulsive devices, combustion occurs at subsonic speeds. Scramjets are simple devices compared to jet engines which also are air breathing propulsion. Unlike jet engines scramjets doesn’t have any moving parts to compress the incoming air that makes scramjets less complex than the jet engines. Scramjet typically works well in hypersonic speeds and is not suitable for supersonic and subsonic speeds. For supersonic speeds ramjets are the best option. In ramjets the intake decelerates the incoming air to subsonic speeds and then ignites the subsonic compressed air to supersonic speeds. But in scramjets the combustion take place at supersonic speeds so does the exhaust gases accelerate to hypersonic speeds. Aircraft's Rotations An aircraft in flight is free to rotate in three dimensions. It is necessary to control the attitude or orientation of a flying aircraft in all three dimensions. In flight, any aircraft will rotate about its center of gravity, a point which is the average location of the mass of the aircraft. We can define a three dimensional coordinate system through the center of gravity with each axis of this coordinate system perpendicular to the other two axes. We can then define the orientation of the aircraft by the amount of rotation of the parts of the aircraft along these principal axes. YAW
The yaw axis is defined to be perpendicular to the plane of the wings with its origin at the center of gravity and directed towards the bottom of the aircraft. A yaw motion is a movement of the nose of the aircraft from side to side. A positive yaw, or heading angle, moves the nose to the right. The rudder is the primary control of yaw. PITCH The pitch axis is perpendicular to the yaw axis and is parallel to the plane of the wings with its origin at the center of gravity and directed towards the right wing tip. A pitch motion is an up or down movement of the nose of the aircraft. A positive pitch angle raises the nose and lowers the tail. The elevators are the primary control of pitch. ROLL The roll axis is perpendicular to the other two axes with its origin at the center of gravity, and is directed towards the nose of the aircraft. A rolling motion is an up and down movement of the wing tips of the aircraft. The angular displacement about this axis is called bank. The pilot changes bank angle by increasing the lift on one wing and decreasing it on the other. A positive roll angle lifts the left wing and lowers the right wing. The ailerons are the primary control of bank. The rudder also has a secondary effect on bank. In flight, the control surfaces of an aircraft produce aerodynamic forces. These forces are applied at the center of pressure of the control surfaces which are some distance from the aircraft cg and produce torques (or moments) about the principal axes. The torques causes the aircraft to rotate. The ability to vary the amount of the force and the moment allows the pilot to maneuver or to trim the aircraft BASICS OF AERODYNAMICS Aerodynamics is the study of forces and the resulting motion of objects through the air. Anything that moves through air reacts to aerodynamics. Here we only discussing about aircraft's aerodynamics. FOUR forces of flight
A force may be thought of as a push or pull in a specific direction. A force is a vector quantity so a force has both a magnitude and a direction. When describing forces, we have to specify both the magnitude and the direction. The AN/APG-77 is a multifunction Low probability of intercept radar installed on the F-22 Raptor fighter aircraft. It is solid-state, active electronically scanned array (AESA) radar. The APG-77(V) radar for the F-22 is based on the successful APG-66/68/80(V) family of fire control radars. It is a multifunction solid-state, active electronically scanned array (AESA) Low probability of intercept radar installed on the F-22 Raptor. It provides 120° field of view in azimuth and elevation. The active electronically scanned array (AESA) is a fixed, active array consisting of 1956 transmit/receive modules module low-power X-band transmit or receive modules that are electronically scanned or "steered," with no mechanical movement, each about the size of a gum stick. The separate transmitter and receiver for each radiating element results in increased agility, low radar cross-section, and wide bandwidth.
Its fast phase shifting and a lower level of energy is radiated by the side lobes, eliminating the spillover common to feed horn/reflector antennas. This makes the radar less detectable and reduces ground clutter. The APG-77(V) does not have a main processor of its own. Instead, two central integrated processors (CIPs), which can each process 700 million instructions per second with growth capacity up to 2,200 million, integrate the radar with other sensors and the electronic warfare systems on the F-22. Stealth is the corner stone of 5th gen air fighters. Stealth tech also called Low Observable (lo) tech is a collection of techniques that makes objects less visible to radar, infrared, sonar and other detection methods. Stealth d doesn't mean it is invisible stealth is used to delay the detection as far as possible. Stealth is applicable to aircraft's ships, submarines, missiles, satellites & even personals too. Here we only talk about stealth aircraft's.
Before continuing we are like to give a small description about how a radar works makes further reading easier. The basic idea is the radar antenna to send out a burst of radio energy, which is then reflected back by any object it happens to encounter. The radar antenna measures the time it takes for the reflection to arrive, and with that information can tell how far away the object is.The metal body of an airplane is very good at reflecting radar signals, and this makes it easy to find and track airplanes with radar equipment. One of the main focuses while developing a 5th gen fighter is reducing the Radar Cross Section (RCS) thus improving the stealth capabilities of the fighter. RCS is a measure of how detectable an object is with radar. A larger RCS indicates that an object is more easily detected This is the era of 5th gen fighters, as of now only US is managed to induct a 5th gen fighter. Other countries like Russia & China is conducting testing of their respective 5th gen fighters. But still there are rumors of developing 6th gen fighters. Countries like Japan & India also developing 5th gen fighters probably they are 5+ gen fighters because they are incorporating some 6th gen technologies like GaN based radar, fly by light, self healing/ self repairing and improved cockpits. Sixth Generation Fighter aircraft (SiGFA) is a fighter being designed on concepts akin to concepts of spacecraft depicted in star wars trilogy. The aircraft, equipped with new concept weapon systems, is expected to become operational by 2030-2050. What will 6th generation fighter aircraft be like and what will be the capabilities of SiGFA? Researches are going on the following areas a) Air Vehicle b) Vehicle/Sensor Protection c) Propulsion d) Warning and Situational Awareness e) Sensors f) Data Fusion g) Offensive/Defensive Systems h) Automatic Target Recognition (Ground and Air) i) Communications, Networks, and Data Links j) Kinetic Weapons k) Non-kinetic Weapons l) Electronic Warfare and Information Operations m) Secondary Power Generation, Storage and Management n) Thermal Management and Heat Rejection o) Human System Integration (HSI) p) Remotely Piloted Aircraft (RPA) and Optionally Manned Systems NEED FOR A 6th GENERATION OF COMBAT AIRCRAFT For any modern air force, achieving air superiority remains the primary mission. Air superiority can be understood as that degree of air dominance which allows air, land, and sea forces to operate free from interference by an opponent’s air forces, while at the same time denying the opponent such dominance. To achieve air superiority, it is not enough to simply defeat an opponent’s air forces, but it is also necessary to sufficiently degrade, disrupt, or deny air defenses and air bases. With air superiority assured, ground forces can then move into areas without fear of attacks from the skies; aircraft can observe and strike the opponent without obstruction; navies can position themselves freely and support ground operations; for example. In operations over the last two decades or so, Allied states had air superiority from the beginning or achieved it very quickly. It is therefore easy to forget that such absolute freedom of action in the air should not be taken for granted in the future. If a country want to possess the best air forces in the world, their fighter jets need to remain at the global technological vanguard. Naturally, at such an early stage of thinking about a 6th-generation combat aircraft, the precise capabilities and requirements of such an aircraft are still very much subject to debate. Indeed, the next few years’ work on a future fighter jet will be devoted to exploring possibilities and clarifying what such a jet should be able to accomplish. Still, most experts converge around a few general features. - extreme stealth, e.g. the jets should be stealthy across a greater range of spectrums - engine efficiency at all flight speeds, from subsonic to multi-Mach speeds - advanced exterior skin constructed with nano-technology and meta-material, i.e. material engineered to exhibit properties not found in nature - exceptionally powerful computer networking and communication capabilities - extremely sensitive sensors - the option of unmanned flight - advanced weapon systems, possibly lasers and other directed energy weapons - Morphing capability (the ability of an aircraft to change its shape while in flight) Jet fighter engines are evolving gradually in comparison to the exponential advances in aerospace technologies like radar, software, sensors, stealth, and weapons. A fundamental factor is that aircraft engines are bound by the physics of jet propulsion systems and the limits of an airplane’s aerodynamics, size, and weight.
Still, current engine development efforts are set to advance jet engine technology substantially over the next few years. SiGFA Adaptive-Cycle Engines/variable cycle engines. Such engines are different from previous models because they possess an additional third manageable air stream. This dramatically improves the aircraft’s reach, fuel efficiency (enabling supercruise at more fuel efficient rates), and speed. The third stream of air in the variable cycle engine can be controlled by the pilot. By opening or closing the third air stream, the pilot can adjust the fuel intake of the jet engine and optimise its performance (the pilot has the option to exit cruise mode and significantly increases thrust as needed). This enables smooth transition from strike aircraft speeds (supersonic) to cruising (subsonic). The engine will also include light‑weight ceramic‑matrix composite materials that will allow the engine to operate above the melting point of steel. Adaptive-cycle engine has an adaptive fan, which allows the engine to vary its bypass ratio depending on its altitude and speed due to a third stream of air. Air flows through the third stream as needed to increase or decrease the bypass ratio of the engine—or alternatively use the extra airflow for cooling. We can effectively vary the performance of the engine across the flight envelope. At high-supersonic speed, the third stream can reduce spill drag by letting the excess air flow through the engine— however performance above about Mach 2.2 is still limited by the physics of air inlet geometry. The third stream does help supersonically very much and this third stream of air provides additional heat sink capacity that both reduces the aircraft's infrared signature and enables the aircraft to accommodate directed energy weapons. General Electric made substantial progress in adaptive cycle or variable cycle engines as a result of the US Air Force's Adaptive Versatile Engine Technology (ADVENT) program. The aim of the ADVENT programme is to develop a variable cycle engine that provides for 5 to 10% more thrust and a 25% reduction in fuel consumption compared to the jet engines in current F-35s. A 6th-generation combat aircraft would need to travel substantially faster and with less fuel intake than current 4.5th- and 5th-generation jets. After a plane achieves Mach 1 without afterburners, i.e. in supercruise mode, it can achieve faster speeds with relatively less energy. The variable cycle engine will possibly advance propulsion to speeds that are three to four times the speed of sound. At present, flying at these speeds has been achieved for only short periods of time. An engine that can sustain Mach 3 to 4 and maintain fuel efficiency would be a dramatic technological development. Some posit that a 6th-generation jet may be able to achieve hypersonic travel (five times the speed of sound or more), although most industry insiders doubt this would be possible by 2030, barring a revolution in engine technology. But hypersonic fight entails a whole new range of materials development, for sensors, fuzes, apertures, etc to ensure which must operate in that intense heat environment at ... Mach 5-plus Use of electric propulsion for SiGFA is an another possibility. A prototype of the first Japan-made stealth fighter X-2 Shinshin, formerly called ATD-X may be equipped with powerful batteries and electric motors. Such a hybrid would take advantage of a jet engine's speed and use electric generators so as to give power to directed-energy weapons, including lasers. It would also fly at low speeds. The Mikoyan MiG-35 (NATO reporting name: Fulcrum-F) is a Russian fighter aircraft that is a further development of the MiG-29M/M2 and MiG-29K/KUB fighters. It is classified as a 4++ generation jet fighter by Mikoyan. The first prototype was a modification of the aircraft that previously served as MiG-29M2 model demonstrator. While the airframe is similar, the aircraft is practically a new design under the hood. Compared to the original Fulcrum, the MiG-35 adds a completely new fly-by- wire control system, a lighter airframe, more fuel capacity, more efficient engines and thrust-vectoring nozzles. The single seat version is designated MiG-35 and the two-seat version is MiG-35D
The MiG-35/MiG-35D exhibits advancements on MiG-29K/KUB and MiG-29M/M2 fighters in combat efficiency enhancement, universality and operational characteristics improvement. The most important changes are the Phazotron Zhuk-AE active electronically scanned array (AESA) radar, the RD-33MK engines and the newly designed Optical Locator System, OLS-35. The final configuration of the MiG-35's on-board equipment has been left open intentionally using the MIL-STD-1553 bus. The main advantage of an open architecture configuration for its avionics is that future customers will have options to choose from components and systems made by French, Israeli, Russian and United States companies. The new AESA radar and the uniquely designed optical locator system (OLS) make the aircraft less dependent on ground-controlled interception (GCI) systems and enable the MiG-35 to conduct independent multi-role missions. An alternate hypersonic air breathing propulsion concept to the scramjet is the shock-induced combustion ramjet (shcramjet) also called Oblique Detonation Wave Engine (ODWE), or simply referred to as Shock-Ramjet Engine) is a new concept in air breathing ramjet engines, proposed to be used for hypersonic, as well as, single-stage-to-orbit (SSTO) propulsion applications. While scramjet concepts rely on the diffusive burning of injected fuel, the shcramjet concept aims to avoid a long combustion chamber by injecting the fuel in the inlet of the vehicle and burning the fuel/air mixture through a shock wave. This reduces the weight of the engine (which directly leads to substantial reduction in overall vehicle weight of a hypersonic wave rider design) and takes advantage of the typically long inlets found at hyper velocities. Thus shcramjets are more efficient than scram jet. Also, the shcramjet is believed to have a better overall propulsive performance than the scramjet at higher Mach numbers, especially above Mach 12. Recent researches have stipulated that air breathing engines such as scramjets and shcramjets provide a more efficient high-speed vehicle propulsion system than rocket engines. These potential advantages of shcramjet have recently attracted substantial efforts into their research all around the world. In order to establish the shcramjet as a viable concept, shcramjet research must seriously address 1) Achieving adequate mixing prior to the shock-induced combustion, and 2) The prevention of premature ignition in the inlet. (Followers can expect more on shcramjets as well as other latest propulsive devices in near future stay with us) References
1) Wikipedia 2) Thomas E. Schwartzentruber and Jean P. Sislian†,University of Toronto Institute for Aerospace Studies, Downsview, ON, Canada M3H 5T6 and Bernard Parent‡ Department of Aerospace Engineering, Seoul National University, Seoul, 151-744, Korea. Yes ,they are. After reading this article you would agree to what I want to say. What were you imagining that you would manoeuvre through enemy airspace , would trick the enemy SAMs, dodge the enemy fighters and bomb your target??? Very soon we may not need to do this. Top military nations are in a run to make hypersonic missiles. Hyper sonic weapons can be more survivable because of the extreme speed and altitude. They would be hard to stop. Hard to interpret and even more tedious to engage. Hypersonic means something that can achieve the speeds 5 times that of Sound. So Militaries want missiles and aircraft that can achieve Hypersonic Speeds. But how they are going to develop such fast missiles or aircraft ????? There are 2 kinds of approaches to solving the hypersonic challenge. Scramjet and Boost glide. ScramjetsScramjet abbreviated as (supersonic combustion ramjet) is a kind of air breathing jet engine it uses its high power to accelerate the vehicle into hypersonic speeds. As it accelerates more air and fuel is pushed into the engine allowing it to accelerates into hyper sonic speeds. It collects the oxygen from surrounding air via it's air intakes and increase it's burning efficiency. The have mechanism just like turbo fans difference is just that they don't have any 'fans'. ScramJets cannot accelerate at Zero Speed. It means that first they must be given a speed of sound(sonic) then only they would start. For taking them to such high speeds they are carried by Rockets or Aircraft. Air is taken in intakes at supersonic speeds and then mixed with fuel and burned. Till 1990 only USA , USSR and some European countries possessed that technology. But now countries like Australia, China and India are doing experiments in that a direction. Boost Glide.Boost glide is a kind of re entry into the atmosphere from extremely high altitudes. Boost-glide weapons have potentially longer ranges, can generally transport a heavier payload over a given range, are capable of midcourse manoeuvring, and fly at lower altitudes. They are First taken in Space and then 're-entered' into earth's atmosphere. At the time of re-entry their speed is around Mach 20, that is 20 times the speed of sound. But as they enter atmosphere they start making friction with air and thus their speed gets reduced. They are launched by rockets just like spacecraft. After entering earths atmosphere. They Glide. While gliding they slowly reduce their altitude and fly at low levels but as fast as Mach 7. They have got retro rockets at their back which help them adjust their direction. They contain the main warhead which simply means 'bomb'. Upon reaching their target they release warhead which impacts on the target. The Vehicle returns to base and lands like an aircraft. This concept has been developed so that Countries should be able to launch attacks anywhere in the world within one hour and that too launching the aircraft from their land. Instead of making military bases on foreign land. To read which nations are developung such programs and what are those awesome vehicles . Click on the button below. Do tell us what do you feel about this article , Next Generation Weaoon Technology started as a facebook page and intends to perform detailed analysis and discussions releted to the advancements in weapons. History has always showed that advancement in weapon technology leads to advancement in civillian technology. Inventions ranging from Wrist watch to Refridgerator were all developed from or for weapons amd wars. We therefore empahsise on spreading awareness about latest warfare techs. The primary objective of our page is to provide detailed ,basic knowledge about weapons which we dont get from our school and college textbooks. Click on the above button to visit our Facebook Page. |
AuthorPalash Choudhari Archives
June 2021
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