Lockheed Martin/Boeing F-22 Raptor

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Pa naravno da je bitna taktika, a hvala bogu da nema toga sto je savrseno pa i F22...

Evo malo na Global Security su odredjeniji oko stealth karakteristika F22.



F-22 Raptor Stealth
A quick look at the F-22 reveals an adherence to fundamental shaping principles of a stealthy design. The leading and trailing edges of the wing and tail have identical sweep angles (a design technique called planform alignment). The fuselage and canopy have sloping sides. The canopy seam, bay doors, and other surface interfaces are sawtoothed. The vertical tails are canted. The engine face is deeply hidden by a serpentine inlet duct and weapons are carried internally.

Advances in low-observable technologies provide significantly improved survivability and lethality against air-to-air and surface-to-air threats. The F-22's combination of reduced observability and supercruise accentuates the advantage of surprise in a tactical environment. The most publicized and most revolutionary technology for aircraft is stealth. Stealth makes an object become very difficult to detect by sensors such as radar, heat seekers (infrared), sound detectors and even the human eye. While not invisible, the F-22's radar cross section is comparable to the radar cross sections of birds and bees. Compared to other current fighters, the F-22 is much more difficult to detect.

To make a stealthy aircraft, designers had to consider five key ingredients: reducing the imprint on radar screens, muffling noise, turning down the heat of its infrared picture, stifling radio transmissions and making the plane less visible. The leading and trailing edges of the wing and tail have identical sweep angles (a design technique called planform alignment). The fuselage and canopy have sloping sides. The canopy seam, bay doors and other surface interfaces are saw-toothed. The vertical tails are canted. The engine face is deeply hidden by a serpentine inlet duct and weapons are carried internally.

The F-22 represents a significant design evolution beyond the highly successful F-117A Nighthawk stealth fighter, with performance not achievable by today's front-line fighters. Low observable, or stealth, technology has advanced to the point where conventional aerodynamic configurations can be made incorporating low observability without compromising aerodynamic performance or increasing costs significantly. Design development risk was greatly reduced by the performance demonstrated in the dem/val program where angle of attack attitudes up to 60 degrees were flown. The validity of the low observability features of the F-22's design were confirmed by full-scale pole model testing.

Low observability is achieved by a range of measures. The F-22 employs planform shaping and faceting with blended facet boundaries, the latter a necessary concession to high performance aerodynamics. This is apparent in the shape of the nose, the fuselage sides about the inlets and engines, and the upper forward fuselage. Lockheed/B/GD used serrated edges extensively, as with the F-117A, to control the returns from panel boundaries, this is very visible on the undercarriage and weapon bay doors. The planform results in a multiple lobe design, as the boundaries of the major surfaces are not parallel with respect to each other. Planform return lobe structure is defined by the radiation pattern lobes resulting from surface wave reflections which occur at the leading and trailing edges of the airframe's major surfaces. The objective of lobing is to concentrate this unavoidable radar return into specific directions so as to minimise frontal/aft/beam aspect return and maximise scintillation in the direction of the lobe. Scintillation is a measure of how rapidly the size of the return varies with angle, the greater this variation, the more difficult a target is to track. The lower the number of lobes and the narrower the lobes, the lower the probability of detecting any return.

Radar absorbant materials, or RAM is applied sparingly on the F-22 airframe as opposed to the entire airframe on the F-117. This is because designers have incorporated curves on crucial surfaces and edges, which lessens the need for RAM. For example, new ceramic-matrix RAM is utilized on the engine exhaust nozzles to reduce radar and IR signatures, and a greater amount of wide-band structural RAM is used on the wing edges. The interesting shape of the radome on the F-22 reflects radar signals at all frequencies except the precise wavelengths emitted from the F-22. This can be attributed to the radome's low bandpass type.

To apply the complex system of paints and coatings necessary to meet the F-22's stringent radar cross section (RCS) requirements takes not only state-of-the-art equipment and hands-on technicians, but also a wide-ranging support system. A new type of paint, or topcoat, increases the F-22 Raptor's stealthiness by reducing its vulnerability to infrared threats. To meet F-22 requirements, Boeing developed the topcoat to protect the aircraft against a broad range of wavelengths. The new paint replaces conventional topcoats, performing all the required environmentally protective functions while also reducing the aircraft's vulnerability to detection. The topcoat does not add to the F-22's weight, and provides performance enhancement at a very modest cost. It is applied in a two-tone camouflage design, patterned after the F-15 "Mod-Eagle" paint scheme. Development of the new topcoat began during the early stages of the F-22 program. Since that time, a small team at Boeing in Seattle has worked to refine the paint and improve its application characteristics in a production-level environment. Technicians at Lockheed Martin painted the first few aircraft by hand, however, robotic application is planned for future Raptors, including Raptor 04, which is scheduled to fly this summer. The topcoat application for each Raptor is expected to take one to two days.

Another important feature of the F-22's stealth characteristics is the new low-RCS air data system. This system uses four ports distributed along the forward fuselage to reduce emission control (EMCON). In addition, the F-22 is the first fighter aircraft to include a completely frameless canopy. This eliminates RCS reflections from the windshield arc without compromising structural integrity.

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Moram da ispravim jednu gresku. F-22 i Eurofighter nisu jedini avioni koji imaju mogucnost superkrstarenja. Pre njih su imali i jos imaju Su-27 i Mig-31, tako da su Rusi to imali 20 godina pre Amerikanaca. Dali neko zna kakav je Raptor u poredjenju sa Su-47 Berkut?

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Su-47 se ne moze meriti sa F-22 jer je to tehnoloski demonstrator i nikada nece uci u naoruzanje. Takodje je i u odnosu na F-22 zastareo.

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Hvala na informaciji. Ja sam mislio da ce on uci u naoruzanje kao MFI.

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OKB Suhoj radi na razvoju lovačkog aviona pete generacije i njegova radna oznaka je T-50, a o njemu je pisano u temi:

http://www.mycity.rs/Vojno-tehnicka-dostignuca/T-50-novi-ruski-lovac.html

Međutim, što se tiče Berkuta, tačno je da VVS Rusije nije podržao razvoj serijske varijante aviona, ali isto tako ni u samom Suhoju nisu definitivno odustali od njega. Naime, u nekoliko navrata su predstavnici firme nagovestili da bi korisnik njihovog aviona mogla da bude ratna mornarica. Za ulogu palubnog lovca poželjne su superiorne osobine obrnute strele krila u režimima poletanja i sletanja na malim brzinama, što je gotovo idealno za nosače aviona. Problematična tehnologija izrade krila obrnute strele razrešena je primenom kompozitnih materijala koji sačinjavaju čitavih 90% mase nosećih površina. Još jedna činjenica ide u prilog tome da se nije definitivno odustalo od Berkuta - a to je da je on preimenovan iz radne verzije S-37 i da je dobio novu oznaku Su-47 u skladu sa označavanjem aviona u ruskom vazduhoplovstvu. On se koristi kao tehnološki demonstrator, odnosno kao platforma za ispitivanje novih tehnologija, tako da se ne može reći za njega da je zastareo.

Druga stvar, kada su u pitanju motori za avione Su-27 i MiG-31 - to da oni imaju mogućnost superkrstarenja - ipak ne postoje čvrste potvrde za to.

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GOKU91 ::Moram da ispravim jednu gresku. F-22 i Eurofighter nisu jedini avioni koji imaju mogucnost superkrstarenja. Pre njih su imali i jos imaju Su-27 i Mig-31, tako da su Rusi to imali 20 godina pre Amerikanaca. Dali neko zna kakav je Raptor u poredjenju sa Su-47 Berkut?

Malo si polupao loncice za su27 i mig 31...

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Citat:On se koristi kao tehnološki demonstrator, odnosno kao platforma za ispitivanje novih tehnologija, tako da se ne može reći za njega da je zastareo.

Kada je napravljen bio je zastareo za najnovijim zapadnim borbenim avionima. O daljim modifikacijama nemam novih podataka.

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zixo ::
Kada je napravljen bio je zastareo za najnovijim zapadnim borbenim avionima.

Pošto je ovo tema o F-22, možda smo malo otišli u OT. Nadam se da nam moderatori neće zameriti. Ipak ovo ima veze sa Raptorom, makar indirektne.

Šta sam hteo da kažem?
U Aeromagazinu br.7 iz februara 1999. godine, pojavio se tekst o Berkutu, autor je bio docent dr.Slavko Pokorni dipl.ing. Evo šta piše u uvodu teksta:

Citat:Iako su Amerikanci bili najdalje otišli u rezultatima postignutim u istraživanju mogućnosti aviona sa krilom tipa – obrnuta strela, Rusima je pošlo za rukom ono što Amerikancima nije – napravili su prvi avion demonstrator sa krilom tipa – negativna strela, koji, ako bude para, obećava da će postati lovački avion pete generacije.

U štampi se pojavila vest, da je Rusija napravila avion S-37 "Berkut" - višenamenski lovac pete generacije, koji ispunjava zahteve nadzvučnog supermanevribilnog (supermanevarskog) aviona smanjene uočljivosti za radare i za sredstva IC - otkrivanja, o kome za sada ima relativno malo podataka. Poletanje ovog aviona s ponosnim imenom "Berkut" (Carski orao) se smatra istorijskim događajem čak i za rusku avijaciju, pa i novom etapom u istoriji razvoja ruske lovačke avijacije, iza koje, poznatoje, stoje izvanredni rezultati.

S-37 je demostraciono-eksperimentalni avion, namenjen za proveru novih tehničkih rešenja u oblasti aerodinamike, sistema za upravljanje letom i dinamike kretanja letelica. Najvažnija specifičnost ovog aviona je, što se u njegovoj konstrukciji koristi krilo tipa obrnuta strela (KOS). Izbor takvog konstrukcionog rešenja je logičan nastavak dugotrajnog rada firme "Suhoj" na iznalaženju tehničkih rešenja povečanja, pre svega, manevarskih mogućnosti aviona. S-37 je principijelno novi avion, koji je svoj prvi let obavio 25. septembra 1997. godine, samo 18 dana posle prvog leta svog američkog suparnika F-22A Raptor (Rusi ovaj naziv prevode kao Lešinar, a izgleda da je to neko mitsko vrlo krvoločno stvorenje) Firme "Lokid Martin" (Lockheed Martin), koji je prvi put poleteo 7. septembra 1997. godine. F-22 je posle toga poleteo još jednom - 14. septembra, a na doradu je vraćen do jula 1998. godine.

Ja i dalje smatram da se ne može za njega reći da je zastareo.

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To si potpuno u pravu. Ali ajde da se vratimo na F-22. Po meni on je potpuni promasaj. Cena od 120 miliona a po nekima i preko 300 miliona je isuvise za jedan avion. Raptor ima stelt tehnologiju koja je izuzetno skupa i amerikanci su u nju ulozili milijarde dolara, a ispade da se i pored stelta avion moze otkriti radarima sa decimetarskim skeniranjem (kao sto je onaj nas ruski radar sto je otkrio F117). Rusi prave nove radare koji imaju i centimetarsko i decimetarsko skeniranje i oni su u sistemima S-400. Raptor ima samo bolju elektroniku od Su-27 i Mig-29 i svih njihovih podverzija, ali nema bolju aerodinamiku i nema supermanevribilnost tako da Rusi u pstojece lovce mogu samo da ubace novu elektroniku i da ih pretvore u lovce 4++ generacije koji mogu da se nose sa F-22. Ruski avioni Su-37 i Mig-29 OVT imaju vektorisan 3D potisak, a F-22 ima 2D.

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Citat:S-37 je demostraciono-eksperimentalni avion, namenjen za proveru novih tehničkih rešenja u oblasti aerodinamike, sistema za upravljanje letom i dinamike kretanja letelica.

Pa vidite i sami za sta je pre svega namenjen. Koliko znam el.oprema je inferiorna kada bi se poredila sa F-22, a takodje nisam siguran ni u steltnost.