Tranh luận về Tên lửa đối không và các Hệ thống dẫn đường tấn công cho tên lửa đối không

Tôi có chút góp ý với các bạn:
Than_Dau_tuat nóng quá, không nên như thế khi thảo luận.
Các bạn Ducsniper, Vietkedoclap...: Tôi chỉ dám nói là theo nhận xét của tôi, có lẽ các bạn chưa được nghiên cứu hoặc giả đã quên mất một số khái niệm vật lý cơ bản. Hơn nữa các bạn thiên về các tài liệu bằng tiếng Anh. Quan điểm của tôi ta nên công bằng: Nếu ta dẫn chiếu các review bằng tiếng Anh, trên quan điểm phương Tây về các hệ thống của Nga (liên Xô) thì nếu không có nguồn thông tin của người Nga về các hệ thống phương Tây, và ta chưa đọc được những quảng cáo của Nga, bằng tiếng Nga về hệ thống vũ khí của họ, rõ ràng sẽ có thiên lệch.
Quay lại vấn đề cụ thể.
Các bạn phản đối Than_dau_tuat về chuyện tên lửa AIM phải quay vòng để đuổi mục tiêu là không đúng. Về bản chất, tất cả các tên lửa IR các đời đầu (trước khi áp dụng kỹ thuật phân tích ảnh nhiệt) đều không thể đánh chặn mục tiêu mà phải đánh đuổi. Do vậy vị trí tấn công bao giờ cũng ở cầu sau mục tiêu, Nếu đánh ở cầu trước, góc tấn công của tên lửa phải lớn để trong quá trình bay, nó có thể đổi hướng vào bán cầu sau mà không mất dạng mục tiêu.
Các bạn có đề cập đến trễ của datalink hay radio command làm cho vô hiệu hoá khả năng điều khiển, song theo tôi biết, datalink cũng như radio command, sử dụng sóng radio có vận tốc ánh sáng (sóng điện từ), toàn bộ hệ thống vũ khí đều là real-time, như vậy độ trễ chỉ cỡ hàng chục nano-s, nhân với vận tốc của tên lửa vài M, thì sai lệch chỉ vài chục cm nếu tính ở tầm xa nhất của tên lửa là 200km. Không có chuyện trễ này, theo quan điểm của tôi.
Tôi đồng ý đến 4 yếu tố cần có của tấn công mọi hướng của than_dau_tuat, song có điểm này: xuất phát mọi hướng là thứ yếu, đạt được tới mọi huớng mới là tiên quyết. Ví dụ như trường hợp bắn ngược (góc 180 độ) thì tên lửa phải có khả năng rơi, xoay và định hướng bắt được mục tiêu bằng các thông tin của máy bay cấp cho, có nghĩa nó phải đạt được một thao tác phức tạp trong một thời gian có hạn. Đây là vấn đề cực lớn đối với hệ thống điều khiển.
than_dau_tuat bình tĩnh 1 chút, ta đang nói chuyện kỹ thuật, không nên đả phá cá nhân mà chỉ nên đả phá (phản biện) quan điểm của nhau thôi!

Tôi xen tí nhé:
- Tấn công mọi hướng đương nhiên là tính theo aspect angle
- Tấn công mọi hướng được hay không lại chờ xem máy bay (hay chính xác hơn là hệ avionics của nó) có đủ khả năng tìm, theo dõi và khoá mục tiêu trong tất cả các góc lead angle hay không!!!
ví dụ, tên lửa đánh mọi hướng đặt lên F4 thì cũng chỉ bắn trong 1 góc lead giới hạn thôi. Bắn xong rồi thì tên lửa tùy theo may mắn hay không mà va mục tiêu

Tôi có ý kiến:
1/ IRST, như tôi đã tham luận, không phát xạ nên không hội tụ được cái gì hết. Ý bạn nói là nó tập trung (focus) vào mục tiêu chăng?
2/
Cũng như thế, laser đo xa dùng để bật sáng đèn báo vào vùng bắn mà thôi, tên lửa chẳng cần thông tin đó. vì thế nên phi công Nga cũng chẳng cần "quay lại" mà họ chỉ cần chờ vào vùng bắn , hoặc chờ đèn bắn bật sáng (nếu máy tính trên máy bay đủ khả năng tính chuyện đó) là bấm cò thôi.
Về khóa của radar, có lẽ bạn nhầm 1 chút: khóa được là nhiệm vụ chiếu xạ của radar máy bay. Trên giá trước khi phóng, 2 thằng chủ động và bị động đều ứng xử như nhau: nằm im và ngó vào chỗ máy bay bảo. Chỉ khi phóng, radar chủ động mới bật radar riêng của mình, tuỳ vào thiết kế tên lửa.
3/ Về độ trễ, tôi đã post
Về chuyện datalink, có lẽ bạn hiểu nhầm. Cách phát lặp tín hiệu chỉ dùng cho datacommand. Với datalink, tên lửa cũng phải hồi đáp (respond) về thông tin của nó như tốc độ, hướng... và đương nhiên, có cả các thông tin kiểm chứng (parity check) nên không cần phát nhiều lần, chỉ cần được là phát phiên khác ngay.
Hơn nữa datacommand cũng không phát lặp theo thời gian, mà theo tần số hoặc pha. Mỗi lần phát tín hiệu là một thông số khác nhau, update theo dữ kiện của trung tâm. Chẳng có lý gì phát lặp lại 1 tin cũ trong khi tin mới thì đang đầy ra
Lý do dùng đầu đò riêng cho giai đoạn cuối không phải là do datalink, bị trễ, mà chỉ đơn giản do độ phân giải radar máy bay không đủ để dẫn tên lửa tới mục tiêu, nên tốt nhất tới cự ly vài km, khởi động và bám bằng đầu dò của bản thân tên lửa.
Có vài ý kiến!!
Xong ta nhậu

Ý cậu nói là nếu tên lửa tầm nhiệt được bắn đến từ bán cầu trước của máy bay thì nó cũng phải vòng ra sau đuôi máy bay rồi mới quay ngược lại lao vào ống xả ? (vì câu gốc của Than_Dau_Tuat là "tên lửa tầm nhiệt thuần túy là AIM ngày nay... nó cũng không thể tấn công mọi hướng, nên phải lượn vòng ra đàng sau máy bay rồi quay lai tấn công khi góc lớn)
Giả sử tên lửa bắn tới từ bán cầu trước, góc tới 30 độ so với hướng bay của mục tiêu. Theo lý thuyết trên của cậu và Than_dau_tuat, tên lửa sẽ bay ra phía sau mục tiêu rồi mới vòng ngược lại thì turn rate của nó phải là bao nhiêu cho vừa? khi vòng lại gấp gáp như thế, tốc độ bị triệt giảm mạnh, nó phải cần bao nhiêu nhiên liệu và thời gian để lấy lại tốc độ và đuổi kịp mục tiêu đây? và khi đã đi trượt ra phía sau rồi thì làm sao mà "mắt" tên lửa nhìn được ống xả mục tiêu lúc đó đang ở sau lưng?

Bạn thân mến, tôi đang nói về AIM thời đầu, và có cả định nghĩa đời đầu (theo cách nghĩ của tôi) nữa mà?
Vì lý do turn rate và cả FOV của đầu dò, nên tôi nói bắn ở bán cầu trước phải bắn ở góc lớn. 30 độ thì chưa lớn lắm
Đây không phải là lý thuyết của tôi, mà là nhận thức của tôi sau khi tìm hiểu lý thuyết
Thế theo bạn, tên lửa dùng IR seeker hiện đại bắn ở cầu trước thì ở vị trí nào là hiệu quả nhất???
Quên, bạn có thể cho tôi biết turnrate tối đa của AIM không (để tôi thử tính cự ly và góc bắn đảm bảo).

Được chienv sửa chữa / chuyển vào 23:31 ngày 14/09/2005

An air-to-air missile (AAM) is a guided missile fired from an aircraft for the purpose of destroying another aircraft. It is typically powered by one or more rocket motors, usually solid fuelled but sometimes liquid fuelled.
Guidance
Guided missiles operate by detecting their target (usually by either radar or infra-red methods, although rarely others such as laser guidance or optical tracking), and then "homing" in on the target on a collision course. The target is usually destroyed or damaged by means of an explosive warhead, often throwing out fragments to increase the lethal radius, typically detonated by a proximity fuse (or impact fuse if it scores a direct hit). Some missiles rely partially or wholly on their kinetic energy to damage the target, but almost all contain some kind of warhead, even if it is small. Note that although the missile may use radar or infra-red guidance to home on the target, this does not necessarily mean that the same means is used by the launching aircraft to detect and track the target before launch. Infra-red guided missiles can be "slaved" to an attack radar in order to find the target and radar-guided missiles can be launched at targets detected visually or via an infra-red search and track (IRST) system, although they may require the attack radar to illuminate the target during part or all of the missile interception itself. This long range radar antenna (approximately 40m (130ft) in diameter) rotates on a track to observe activities near the horizon. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... Laser guidance is a technique of guiding a missile or other projectile or vehicle to a target by means of a laser beam. ... An infra-red search and track (IRST) system (sometimes known as infra-red sighting and tracking) is a method for detecting and tracking objects which give off infrared radiation such as jet aircraft and helicopters. ...
Radar guidance is normally used for medium or long range missiles, where the infra-red signature of the target would be too faint for a infra-red detector to track. There are two major types of radar-guided missile - active and semi-active. Active radar-guided missiles carry their own radar system to detect and track their target. However, the size of the radar antenna is limited by the small diameter of missiles, limiting its range which typically means such missiles have to use another method to get close to the target before turning their radar set on, often inertial guidance). Semi-active missiles are simpler and more common. They function by detecting the reflection from the target of the launch aircraft''s own radar. This is also known as "beam-riding". However, this means the launch aircraft has to remain a "lock" on the target, limiting its ability to maneuver, which may be necessary should the target counter-attack. It also makes jamming the missile lock easier because the launching aircraft is further from the target than the missile, so the radar signal has to travel further and is greatly attenuated over the distance. An inertial navigation system measures the position and altitude of a vehicle by measuring the accelerations and rotations applied to the systems inertial frame. ...
Radar guided missiles can be countered by rapid maneuvering (which may result in them "breaking lock", or may cause them to overshoot), deploying chaff or using electronic counter-measures. Chaff is the seed casings and other inedible plant matter harvested with cereal grains such as wheat. ... Inspecting an F-16 electronic countermeasures pod Electronic countermeasures or ECM are any sort of electrical or electronic device designed entirely to spoof radar, sonar, or other detection systems. ...
Infrared guided missiles home in on the heat produced by an aircraft. Early infra-red detectors had poor sensitivity, so could only track the hot exhaust pipes of an aircraft. This meant an attacking aircraft had to maneuver behind to a position behind its target before it could fire an infra-red guided missile. This also limited the range of the missile as the infra-red signature soon become too small to detect with increasing distance.
More modern infra-red guided missiles can detect the heat of an aircraft''s skin, warmed by the friction of airflow, in ad***ion to the fainter heat signature of the engine when the aircraft is seen side-on or head-on. This, combined with greater maneuverability, gives them an "all-aspect" capability, and an attacking aircraft no longer had to be behind its target to fire, although launching from such a position typically increases the probability of a hit (however, the launching aircraft usually has to be closer in a tail-chase engagement). An all-aspect missile is one which is able to track a target no matter which way the target faces relative to the missile. ... A tail-chase engagement (or rear-aspect engagement) is one where a surface-to-air missile system or jet aircraft engages another aircraft while the target aircraft is flying away from the attacker. ...
An aircraft can defend against infra-red missiles by dropping flares that are hotter than the aircraft, so the missile homes in on the brighter, hotter target. Towed decoys and infra-red jammers can also be used. However, the latest missiles such as the ASRAAM use an "imaging" infra-red seeker which "sees" the target (much like a digital video camera), and can distinguish between an aircraft and a point heat source such as a flare. They also feature a very wide detection angle, so the attacking aircraft does not have to be pointing straight at the target for the missile to lock on. Instead, the pilot can use a helmet mounted display and target another aircraft by looking at it, and then firing. This is called "off-boresight" launch. In order to maneuver sufficiently from a poor launch angle at short ranges in order to hit its target, missiles are now employing gas-dynamic flight control methods such as vectored thrust, which allow the missile to start turning "off the rail", before its motor has accelerated it up to high enough speeds for its small aerodynamic surfaces to be useful. Bell bottoms are trousers that become more wide from the knees downwards. ... The AIM-132 Advanced Short Range Air-to-Air Missile is a British air-to-air missile with infra-red guidance. ... A gas-dynamic control system is one where the path of an object in flight is controlled by either the generation or redirection of gas flow out of an oriface rather than with the tra***ional movable control surfaces. ... Thrust vectoring is the ability of an aircraft to direct the thrust from its main engine(s) in a direction other than parallel to the aircrafts length. ...
Design
Air-to-air missiles are typically long, thin cylinders in order to reduce their cross section and thus drag at the very high speeds they typically travel at. At the front is the seeker, either a radar system, radar homer, or infra-red detector. Behind that lies the avionics which control the missile. Typically after that, in the centre of the missile, is the warhead, usually several kilogrammes of high explosive surrounded by metal that fragments on detonation (or in some cases, pre-fragmented metal). The rear part of the missile contains the propulsion system, usually a rocket of some type. Dual-thrust solid-fuel rockets are common, but some longer-range missiles use use liquid-fuel motors that can "throttle" to extend their range and preserve fuel for energy-intensive final maneuvering. Some solid fuelled missiles mimic this technique with a second rocket motor which burns during the terminal homing phase. There are missiles in development, such as the MBDA Meteor, that "breathe" air (using a ramjet, similar to a jet engine) in order to extend their range. A dual-thrust solid fuel rocket motor is a type where the propellant mass is comprised of two different types or densities of fuel. ... The MBDA Meteor is a highly agile long-range air-to-air guided missile for future complex beyond-visual-range (BVR) threat scenarios. ... A ramjet, sometimes referred to as a stovepipe jet, is a type of jet engine. ...
Modern missiles use "low-smoke" motors - early missiles produced thick smoke trails, which were easily seen be the crew of the target aircraft alerting them to the attack and helping them determine how to evade it.

An infra-red search and track (IRST)
system (sometimes known as infra-red sighting and tracking) is a method for detecting and tracking objects which give off infrared radiation such as jet aircraft and helicopters. Such systems are passive, meaning they do not give out any radiation of their own, unlike radar. This gives them the advantage that they are undetectable. However, because the atmosphere does attenuate infra-red light to some extent (although not as much as visible light) and because weather can adversely affect it also (again, not as badly as purely optical systems), the range compared to a radar is limited. Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... Jet aircraft are aircraft with jet engines. ... A helicopter is an aircraft which is lifted and propelled by one or more large horizontal rotors (propellers). ... This long range radar antenna (approximately 40m (130ft) in diameter) rotates on a track to observe activities near the horizon. ...
Some modern aircraft, typically fighter or interceptors like the Russian Su-27 Flanker or American F-14 Tomcat, carry IRST systems for use in lieu of their radars when the situation warrants it, such as when shadowing other aircraft or under the control of AWACS or GCI, where an external radar is being used to help vector them onto a target and the IRST is used to pick up and track the target once they are in range. With infra-red homing or fire-and-forget missiles, the aircraft may be able to fire upon the targets without having to turn their radar sets on at all. Otherwise, they can turn the radar on and achieve a lock immediately before firing if desired. They could also close to within cannon range and engage that way. Whether or not they use their radar, the IRST system can still allow them to launch a surprise attack. The Sukhoi Su-27 (NATO reporting name Flanker) is a Russian fighter aircraft designed by the Sukhoi Design Bureau (SDB). ... Sailors prepare an F-14 Tomcat for flight on the aircraft carrier USS Abraham Lincoln, in support of Operation Iraqi Freedom (2003). ... US Air Force E-3 Sentry AWACS aircraft is prepared for flight in November 1997 ****pit of RAF E-3 Sentry undergoing upgrades Airborne Warning and Control System (AWACS) is a radar-based electronic system designed to carry out airborne surveillance, and C3 (command, control and communications) functions for both... Fire and forget is the military term for a type of missile which does not require further guidance after launch such as illumination of the target, and can hit its target without the launcher being in line of sight of the target. ... A small cast-iron cannon on a carriage A cannon is a modern day rifled machine gun with a calibre of 20 mm or more (see autocannon). ...
An IRST system may also have a regular magnified optical sight slaved to it, to help the IRST-equipped aircraft identify the target at long range. As opposed to an ordinary [[forward-looking infra[red]] system, an IRST system will actually scan the space around the aircraft similarly to the way in which mechanically (or even electronically) steered radars work. When they find one or more potential targets they will alert the pilot(s) and display the location of each target relative to the aircraft on a screen, much like a radar. Again similarly to the way a radar works, the operator can tell the IRST to track a particular target of interest, once it has been identified, or scan in a particular direction if a target is believed to be there (for example, because of an advisory from AWACS or another aircrraft).
Note that like infra-red homing seekers, an IRST is more likely to detect a target with its engine exhaust pointed towards the detector than away from it. This means that many jet aircrafts will be detected at longer ranges if they are flying away from the IRST-equipped aircraft rather than towards it. However, most IRST systems are sensitive enough to detect the heat of a jet from head-on as well, either infra-red energy generated from the hot air coming out of the engines, from air friction heating the airframe, or both.
Infra-red search and track systems often incorporate laser range-finders in order to provide full fire control solutions for cannon fire or launching missiles. Without knowing the range (which could be estimated using the infra-red signature of the target or other factors, but would be very inaccurate), the IRST can only provide direction and thus not enough information for aiming weapons. A fire-control system is a computer, often mechanical, which is designed to assist a weapon system in hitting its target. ...
Infra-red search and track and forward-looking infra-red are sometimes used interchangeably but a system which has automated searching and tracking functions, rather than being fixed looking forward or manually steerable, is more specifically known as IRST whereas an FLIR is often little more than an infra-red camera hooked up to a monitor. IRST is more often used against aircraft, but can find and track ground targets, whereas FLIRs are more often found on ground attack aircraft.
See also: Forward-looking infra-red A forward looking infrared (FLIR) system is a television camera that takes pictures in infrared. ...

An inertial navigation system measures the position and altitude of a vehicle by measuring the accelerations and rotations applied to the system''s inertial frame. It is widely used because it refers to no real-world item beyond itself. It is therefore immune to jamming and deception. (See relativity and Mach''s principle for some background in the physics involved). Acceleration is the time rate of change of velocity, and at any point on a v-t graph, it is given by the gradient of the tangent to that point In physics, acceleration (symbol: a) is defined as the rate of change (or time derivative) of velocity. ... Rotation is the movement of a body in such a way that the distance between a certain fixed point and any given point of that body remains constant. ... In physics, an inertial frame of reference, or inertial frame for short (also descibed as absolute frame of reference), is a frame of reference in which the observers move without the influence of any accelerating or decelerating force. ... The term Jamming can refer to several things: Jamming as an electronic warfare (EW) - a technique to limit the effectiveness of an opponents communications and/or detection equipment, like Radio Jamming and Radar Jamming E-Mail Jamming- used by electronic political activists or hackers to disable e-mail systems... In physics, the term relativity is used in several related contexts: Galileo first developed the principle of relativity, being the postulate that the laws of physics should take the same form for all observers in uniform motion with respect to each other. ... Machs principle is a hypothesis first stated by the physicist and philosopher Ernst Mach in 1893, which states that: The inertia of any system is the result of the interaction of that system and the rest of the universe. ...
An inertial guidance system consists of an inertial navigation system combined with control mechanisms, allowing the path of a vehicle to be controlled according to the position determined by the inertial navigation system. These systems are also referred to as an inertial platform.

Tên lửa mọi-góc-độ có thể dò được mục tiêu, không quan trọng là nó đối mặt với mục tiêu từ hướng nào (đối đầu, theo đuôi, tạt sườn)
An all-aspect missile is one which is able to track a target no matter which way the target faces relative to the missile. In other words, an all-aspect missile can be launched against a target in a tail-chase engagement, in a head-on engagement, in a side-on engagement, from above, from below, etc.
This is as opposed to older infra-red homing missiles which were only able to track the hot engine exaust of an aircraft if the aircraft''''s engine exhaust was pointing towards the missile seeker, and thus were only really usable in tail-chase engagements. Infra-red homing refers to a guidance system which uses the infra-red light emissions of a target to track it. ...
Được kqndvn sửa chữa / chuyển vào 00:14 ngày 15/09/2005

Tiếp cận từ phía sau:
Bắn từ phía sau thì khoảng bắn hiệu dùng chỉ còn bằng 1/3 hoặc 1/4 so với bắn từ phía trước. Xác suất trúng mục tiêu của tên lửa sẽ rất cao nếu bắn từ phía sau, vì tốc độ tiếp cận giảm.
A tail-chase engagement (or rear-aspect engagement) is one where a surface-to-air missile system or jet aircraft engages another aircraft while the target aircraft is flying away from the attacker. This makes engagement with cannons or infra-red homing missiles easier because of the minimal lateral target movement relative to the attacker and the fact that the hot engine exhaust nozzle(s) are pointing directly at the attacker, making the infra-red seeker''''s task of tracking the target much easier. A surface-to-air missile (SAM) is a missile designed to be launched from the ground to destroy aircraft. ... Jet aircraft are aircraft with jet engines. ... A small cast-iron cannon on a carriage A cannon is any large tubular firearm designed to fire a heavy projectile over a considerable distance. ... Infra-red homing refers to a guidance system which uses the infra-red light emissions of a target to track it. ...
Missiles typically have a very high chance of hitting a target in a tail-chase engagement because of the much reduced closure rate. If the missile is travelling at Mach 2.5 and the aircraft at Mach 1, the combined overtake rate of Mach 1.5 means that the missile should be easily able to respond to any evasive maneuvers the aircraft might perform. Missiles can typically maneuver faster than aircraft and in a tail-chase engagement the target has no real advantage over the missile. Its only real hope is to fly away from the missile fast enough that the overtake rate is reduced to virtually nil, and then force the missile to follow it through several turns, bleeding off its residual energy and causing it to fall away. Mach number (Ma) is defined as a ratio of speed to the speed of sound in the medium in case. ...
It has the disadvantage, however, of meaning that any missiles or cannon rounds fired at the target must be able to reach and overtake it despite the speed at which the target is moving away. This greatly reduces the effective range at which these munitions can be used. Many missiles have an effective range in a tail-chase engagement on the order of one-third or one-quarter of that in a head-on engagement. In ad***ion, in the case of an engagement between two aircraft, the attacking aircraft will probably have to engage afterburner and chase the target down, using up a lot of fuel in the process. Materiel (from the French for material) is the equipment and supplies in Military and commercial supply chain management. ... A missile (British English: miss-isle; U.S. English: missl) is, in general, a projectile?"that is, something thrown or otherwise propelled. ... A Head-on engagement is one where a surface-to-air missile system or jet aircraft engages another aircraft while the target aircraft is flying towards the attacker. ... For other uses of afterburner, see Afterburner (disambiguation). ...
Categories: Military tactics
Được kqndvn sửa chữa / chuyển vào 00:16 ngày 15/09/2005