Virtuelni dogfight

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Virtuelni dogfight

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@Aerofil

Sve sto si rekao je apsolutno korektno!

Doduse, ja sam to isto rekao u nekom od prethodnih postova

Citat:Ali raketa bi trebala da odradi taj manevar (pod tim opterecenjem) samo ako se nalazi iza cilja (juri cilj) i to vrlo blizu.
Posto se raketa krece velikom brzinom na velikoj visini, dovoljan je i mali pokret krilaca sa vrlo malim opterecenjem kako bi ona drasticno promenila svoj polozaj u prostoru (tacka susreta) i presrela cilj pod sobom, jer nema potrebe da juri direktno za njim.


A ako cemo istini za volju mislim da je i Eridan to isto rekao, samo sto se on konkretno zadrzao na cinjenici da ce raketa morati da manevrise na tim velikm visinama (naravno i daljinama) kako bi blagovremeno ispratila, ondnosno pokusala da presretne cilj, pa je u tom slucaju izrazio sumnju u dovoljnu brzinu procesuiranja podataka i reakciju upravljackih povrsina.

Ok, njegova sumnja je logicna, ali ako proizvodjac tvrdi da je raketa u stanju da pogodi cilj koji manevrise pod opterecenjem od 8 G i ako je to testovima i dokazano, ocigledno je da su sve to vrlo dobro ukomponovali.

Moram da kazem da je Eridan bio ipak upravu za onih 361 G, ali posto je to meni u trenutku delovalo strasno puno, pomislio sam da je greska.
Znaci greska je moja!

Istina je da povecanje G sile odgovara kvadratu brzine, ali ja moram da priznam da mi je matematika slabija strane iz razloga sto je odavno nisam koristio Embarassed

Evo jednog finog primera:

Citat:Missile must follow track of turning aircraft, and G force in a turn is square of true speed.
AIM-120D rocket second pulse burning push speed up to about Mach 3.5. Ratio 3.5 / 0.95 = 3.7 which squared is 13.5. So AIM-120D must pull 13.5 times G bigger than Sukhoi. Some say biggest possible G of AIM-120D is 30, so divide by 13.5 and get Sukhoi to pull only 2.2 G to outturn AIM-120D.
Say AIM-120D lights seeker at 20 km, missile closing at 3,700 kph. So, takes 20 seconds to reach Sukhoi. Radar Warning Receiver (RWR) tells direction of incoming missile, so Sukhoi turns to put missile in rear quarter and starts high-G, jinking barrel roll more than 2 G. I think closer to 5G. Sukhoi has thrust vector jets [Ed: TVC nozzles], so turning at 5 G for 20 seconds no problem. Missile cannot track barrel roll, so fly past and loses lock.


Ima tu jos puno interesantnih stvari o kojima moze da se raspravlja, vezano za izbegavanje rakete, kao sto je optimalan "corner speed" kako aviona tako i rakete, promena ugaone brzine u zavisnosti od realne brzine rakete koja se menja samo usporenjem koje je izazvano promenom trajektorije, a ne oduzimanjem gasa (doduse ram jet rakete bi mogle biti u stanju, u zavisnosti od pogonskog goriva, da regulisu brzinu), maksimalni napadni uglovi itd.

Fakat je da avion moze da izbegne skoro svaku raketu, ali fakat je da su i rakete u stanju da pogode cilj.
To sve zavisi od milion faktora i mislim da je to trenutno iznad nasih glava Wink



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sivisoko ::Slazem se sa tobom, ali mislim da ne treba sumnjati da do 2000-te niko u svetu nije imao radar tipa Zalson (sa svim svojim modifikacijama), koji je omogucavao da se postigne to sto je postignuto sa R-37 raketom, sto i dan danas stoji kao neosporeni rekord u svetu avijacije

Ako govoriš o onom čuvenom pogodku sa daljine od 300km, zar tu nije drugi avion koriscen za navodjenje?



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Napisano: 15 Dec 2011 15:53

mean_machine ::sivisoko ::Slazem se sa tobom, ali mislim da ne treba sumnjati da do 2000-te niko u svetu nije imao radar tipa Zalson (sa svim svojim modifikacijama), koji je omogucavao da se postigne to sto je postignuto sa R-37 raketom, sto i dan danas stoji kao neosporeni rekord u svetu avijacije

Ako govoriš o onom čuvenom pogodku sa daljine od 300km, zar tu nije drugi avion koriscen za navodjenje?


Da, mislim da je u tom slucaju bio koristen drugi avion, SU-30 koliko mi se cini, ali ja sam prevashodno mislio na onih 228km i unistenje 4 cilja koji su leteli na razlicitim visinama sa razlicitim brzinama i pri tom izvodili protiv-raketne manevre.

Zasto mislim da do 2000-te nije bilo savrsenijeg sistema za otkrivanje pracenje i navodjenje rakete na cilj, sto je naravno omogucavalo raketi da bude daleko preciznija i da koristi optimalniju, presretacku putanju do cilja?
Pa zato sto ni amerika ni evropa nisu imale PESA ni AESA radar u svojim lovcima do te godine.

Radar sa mehanickom resetkom nije mogao da se poredi sa mogucnostima koje ima PESA radar, tu pogotovo mislim na rezoluciju, pracenje vise ciljeva istovremeno koji se nalaze na drasticno drugacijim visinama i da se pritom navodi nekoliko raketa istovremeno na te ciljeve pod uslovima jakog elektronskog ometanja.

Citat:It was only in the early '90s that many realised that 'single-purpose'
mechanically-scanned radars were a deadline with no future, since attacking
several targets in the track-while-scan mode is mostly publicity, a
promotional trick, rather than a reality, and could not be employed in
action in most of the cases.
The Zaslon radar pioneered the phased array. To date, there have been no
interceptor across the globe that could boast a phased array. Almost all
combat capability of the new interceptor emerged due to the phased array
radar (PAR).
The radars of the time operated a mechanical drive to scan the aerospace.
When the antenna's ray hit a target, the drive would begin tracking the
target, while the pilot would be completely unable to keep abreast of the
situation and see any other targets.
The track-while-scan technique is only a partial solution to the problem,
since it can provide neither wide coverage areas, nor high precision of the
target coordinates.
The emergence of the PAR solves the problem radically. Reorienting the ray
in any direction within the cone of 120œ - 140œ takes the radar mere 0.001
sec.
The targets travelled towards the interceptor in two groups at both higher
and lower altitudes than that of the MiG-31. The targets were detected and
locked on at a range of 140-180 km. Tracking was stable. The experiment was
crucial for the interceptor's designers. It became obvious that their work
had come to the fruition. Even though nearly two years of further tests
loomed ahead, they were sure they would succeed. The second landmark
experiment was the interceptor's simultaneous destruction of four led
targets.
As a result, the following MiG-31 characteristics were confirmed:
- programmed aerospace coverage; detection, lock-on and simultaneous
tracking of up to 10 targets within the 50-2,800 m altitude brackets in both
good and adverse weather conditions with the enemy electronic
countermeasures (ECM) (scan area of -/+ 60deg-70 deg;


- detection range for the SR-71 and F-16-like targets against the ground
makes up 200 km and 120 km respectively;


- 4-target simultaneous engagement with guided missiles in parallel with
calculation of launch parameters;

- control of the interceptor while cueing it in on the targets, discrete
target illumination;
Twenty years later. July 1998. Four Su-30s and two MiG-31s took off the
Savasleika AFB (Nizhny Novgorod region) to be joined later by an A-50
airborne early warning and control aircraft and two Il-78 tanker planes. The
formation passed along the following route: Savasleika - Astrakhan - Moscow
region - Novaya Zemlya archipelago - Savasleika. The crews were not ferrying
their aircraft back and forth, rather, they maintained communications among
themselves and with the A-50 airborne command post, as well as accomplished
a variety of missions en route.
They would assume various group formations - a MiG-31 would lead the Su-30
strike aircraft and enable them attack ground targets, then the Sukhois
would protect the MiG-31s from surface-to-air missiles to enable the
interceptors to stalk a faraway aerial target and shoot it out of the sky.


Mislim da je zaista smesno raspravljati o tome da je do 2000-te neko imao svarseniji sistem od Miga 31, zalson radara i njegovih modifikacija, kao i R-33 rakete i njenih modifikacija.

Koliko me secanje sluzi, mislim da je kod amera prvi AESA radar imao F-15C 2000-te, dok su francuzi uveli svoj PESA na Rafalu isto 2000-te.

Dopuna: 15 Dec 2011 18:34

Evo poredjenja R-37 i RVV-BD

RVV-BD






R-37













Rakete su skoro identicne!

Evo jednog teksta koji bi mozda mogao da baci svetlo na duzinu rada motora?!

Citat:The R-37 is equipped with an Agat 9B-1388RS active radar seeker, with midcourse inertial, data-link and semi-active radar homing capability. A datalink range of at least 100 km was disclosed. The seeker is claimed to be capable of acquiring a 5 square metre target at 21.5 NMI. Range performance varies with the flight profile, from 80 NMI for a direct shot, to a maximum of 215 NMI for a cruise glide profile. In 1994 a trial round killed a target at 162 NMI, a record for a BVR missile.

Ovde postoje dva razgranicenja:

cruise glide profile: je profil leta koji podrazumeva maksimalni domet u konfiguraciji kada motor prestane sa radom.

direct shot: je profil koji bi trebao da podrazumeva domet sa motorom u aktivnoj fazi.

Ako uzmemo prosecnu brzinu rakete na putanji od oko 6000km/h, dolazimo do zakljucka da ce joj trebati negde oko 90 sekundi da predje razdaljinu od 80NM.
Naravno tu moze da se radi o plus ili minus 90 sekundi, jer ne znamo tacno koja je prosecna brzina rakete, ali to bi otprilike odgovaralo onoj cifri od oko 100 sekundi trajanja rada motora.

Dopuna: 15 Dec 2011 18:44

I evo malo duzeg teksta koji govori o prednostima koje projektil tipa R-37 ili RVV-BD ima u odnosu na druge rakete:

Citat:There is a view held in some circles that Russian counter-ISR missiles are of no concern, somehow, and that if need be attaching a jamming pod, or using a chaff or expendable jammer dispenser will render these weapons impotent.

Reality is not that simple. Since the advent of the 9M9 missile, Russian designers have used jam resistant monopulse radar seekers where possible, and in a larger missile this does not present problems. Examination of photographs of the 9B-1388 antenna shows four coaxial feeds to the antenna, which proves it is indeed a monopulse design. Recent Agat seeker designs have used Texas Instruments TMS320 family digital signal processor chips, which would also be true of any late production variants of the 9B-1388 series. So the assumption that this large and powerful missile seeker will be easily defeated by chaff or jamming is simply naïve. It will be smart enough to defeat most commonly used countermeasures, and have enough power to burn through most jamming.

Another consideration is the possibility of alternate seekers, or multimode seekers on counter ISR missiles. This is a Russian practice dating back decades. Immediate candidates would be derivatives of the passive anti-radiation homing Avtomatika L-111E (Kh-31P) and Agat 9B-1032 (R-27P/R-77PE RVV-PE) seekers, and the digital infrared MK-80ME (R-74 and R-77TE RVV-TE). The use of passive seekers would deny warning time by a large margin, a key issue.

The time which the victim ISR platform has between initial detection of the inbound missile and impact is critical. In a conventional scenario the launching fighter would remain below the radar horizon of the victim system, using a homing receiver to track the bottom of the target's mainlobe, or using offboard cueing. Once a good range estimate exists, the fighter would accelerate to supersonic speed in the direction of the target, and initiate a zoom climb to impart a maximum of energy to the missile as it is released. Given a launch range of 200 NMI, the fighter will appear transiently at the outer edge of the AWACS tracking envelope, and seconds later post launch egress at high speed falling below the horizon again. The missile, a small radar target, will accelerate and climb in the direction of the target until its motor burns out, and then glide in a shallow dive toward the target. At 25 to 40 NMI out the missile's seeker activates, sweeps the programmed acquisition box, and acquires the ISR platform. With little exhaust heat signature at this stage, the missile is approaching at hypersonic speed, emitting pulses as it tracks the target to impact.

The ISR platform under attack does not have much time to react. The only certain warning it will have of an inbound missile occurs when the seeker lights up and initiates tracking, only if a radar seeker is used, which is about 30 to 40 seconds prior to impact, or less if the missile is fired from a shorter range and still under power in the terminal phase. While in theory a radar equipped target such as an AWACS/AEW&C platform could employ the primary search radar to acquire the inbound missile, the small signature of the missile and the geometry of its profile may not yield useful early warning. Defensive manoeuvre is likely to be ineffective.

Initial targeting of ISR platforms will not present difficulties, as these are either emitting radar signals or network datalink signals, the latter usually at maximum power levels. This provides a basic radar homing system like the Avtomatika SPO-32/L-150 coarse bearing to cue the multimode radar, eg N-011 series in late model Sukhois. What we can expect to see emerge in coming years are new Russian passive precision emitter locating interferometer pods not unlike the AN/ASQ-213 HARM Targeting System or Lockheed Martin Aeronutronics (formerly Loral) Target. Acquisition System, or the legacy Avtomatika L-080/081 Fantasmagoria series.

The difficulty in countering long range counter-ISR missiles lies in the extreme ranges from which they are fired, and the high kinematic performance of the fighters taking the shots.


Zato ja i tvrdim da vecina pokretljivijih raketa tipa AIM-120, R-77 i sl. nece biti u stanju da tako lako izvrsi "lock" cilja sa malom odraznom povrsinom, na iole vecim daljinama uz intenzivno elektronsko ometanje, pogotovo na fonu zemlje, kako bi uopste iskoristila tu svoju manevribilnost.

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Da li je moguce da za otkrivanje cilja moze da posluziti radar sa sistema AWACS-a? To jest da nije potrebno da avion koji lansira raketu R-37 ukljucuje svoj radar,vec se osloni na drugi,mocniji i veci radar koji ce mu pruzati podatke o cilju?

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Mislim da je moguce, uz pomoc data linka.

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  • Neimar i savremeni farmer.
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moguce je i upravo su prvi u svetu upravo bile miguske 31 koje su mogle da pucaju na taj nacin. recimo jedna migusa moze da prati do 24 cilja, ali da gadja samo 4 jer recimo da ima samo 4 r33 rakete medjutim povezivanjem sa drugom mikuskom, onai prvi moze preko njega da gadja sa njegove 4 rakete jos 4 cilja. znaci ukupno 8 meta, pa sad ako imas ukupno cetiri aviona i svaki od njih nosi po 6 r33, sledi zakljucak da jedan avion moze da prati i pogadja cak 24 mete upravo pomocu tog data linka i mocnog zaslon radara

upravo je to bila velika prednost do 2000godine migonja u odnosu na nato konkurente.

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Ne vidim koja je korist od toga da jedan MiG-31 navodi rakete drugog.

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  • Neimar i savremeni farmer.
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to stoji mean, ali postoji i ova mogucnost koju sam ja naveo, da jedan mig moze da puca preko ostala tri, a da ovi nisu upalili svoje radar samim tim nisu otkrili svoj polozaj.

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sremac983 ::to stoji mean, ali postoji i ova mogucnost koju sam ja naveo, da jedan mig moze da puca preko ostala tri, a da ovi nisu upalili svoje radar samim tim nisu otkrili svoj polozaj.

Hm MiG-31 je veliki avion koji leti vrlo visoko. Sa i bez radara isto mu je. Videce ga. Sobzirom da ima znatno veci "raspon ruku" mislim da mu to nije problem ali problem jeste ako umesto da npr. cetiri MiG-31 odjednom dejstvuju, dejstvuje samo jedan.

Bilo bi dobro da postoji mogucnost da se navode druge rakete npr. R-27ER. Pa MiG-31 ispali svoje R-33, a onda preuzme navodjenje R-27ER koje ispalio Su-27. Time rasterecuje pilota Su-27, pa ovaj moze da se posveti pripremi sto bolje pozicije za ulazak u blisku borbu. Ali ne naleteh da takva mogucnost postoji, vec da je Suhoj razvijao Su-27P upravo za takav zadatak. Sujeta najverovatnije GUZ - Glavom U Zid

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  • Neimar i savremeni farmer.
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nazalost, moguce je samo medju miguskama to navodjenje i samo sa r33 raketom. kao sto rece mean bilo bi odlicno da postoji ta mogucnost i sa raketama r27, ali nazalost ne postoji.

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