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Izuzetan tekst koji opisuje prednosti koriscenja TVC-a.
Thrust Vectoring:
Imagine two US Air Force Jets with controls not responding, there heading right for each other, the pilots don?t have enough time to eject, there?s a mid-air explosion, and the needless death of American servicemen. About one fifth of peacetime fighter losses during the past few years were due to loss of control. Now imagine that the US has been developing the technology to prevent this for the last decade, but due to budget problems this technology was never installed on our fighters. I?m talking about a Thrust Vectoring Control (TVC). This engineering term describes the use of an engines nozzle to direct the force coming from a jet engine in different directions other then straight out the back. Besides tragic, needless deaths, this technology has a military significance for front line fighter jets. With the wars in Iraq and Afghanistan, Americans have seen the devastating power of our Air Force on Countries without a serious Air Defense network, like Israel or Great Britain. These are countries with not just a Surface to Air Missile (SAM) threat, but an Air Force that can rival ours in its current state. Thrust Vectoring is the technology that will make our fighter jets true rulers of the air, not just on bombing runs, but air-to-air combat, better know as ?Dog Fighting?.
Thrust Vectoring was first used in a trivial form on Nazi Germany?s V-2 rockets. These rockets were devastating to the Allies in WWII with their accuracy due to graphite control vanes that helped the guidance of the missile. Modern rockets, both SAMs and Air-to-Air missiles have been using thrust vectoring to increase their agility in flight, and hence make them more lethal. During the Cold War German military planers recognized the shear numbers of Soviet fighters, and believing that any war would include intense Dog Fighting, began to look for ways to even the odds. Wolfgang Herbst with the Messerschmitt-Boelkow-Blohm, now Deutsche Aerospace, Company led a team in Post-Stall engineering. Post-Stall describes a flight condition in which normal flight controls, like flaps, are no longer sufficient to maintain the flight ability of the aircraft. His team investigated new flight laws to describe the movement of an aircraft in Post-Stall flying conditions.
Why is Thrust Vectoring so important for modern day fighter jets? It?s main purpose is to provide our jets with more mobility in close encounter (within visual range) combat. During a dog fight planes lose speed and altitude to gain a high angle of attack, (AOA). These high AOA can produce a stall, or loss of flight controls in an aircraft, but a jet with thrust vectoring can have a much higher AOA without stalling. A jet with thrust vectoring can perform a maneuver called the ?helicopter? where it is in a controlled flat spin while the nose of the fighter, hence its gun, remains on its target. This added agility can also help fighters avoid deadly missile attacks that have threatened the lives of so many of our pilots in conflicts in Vietnam and Iraq. Thrust Vectoring can also be used to overcome flight limitations in bomb runs, and maintain maneuverability even with the additional bomb load. It can also shorten the takeoff distances, and reduce the ?wind-over-deck? requirement for launching aircraft from our Navy carriers. This technology can also compensate for battle damage to regular flight controls. In the future it could reducing weight and drag by getting rid of radar-reflecting surfaces. Thrust vectoring can also allow for greater thrust expansion ratios by allowing the pilot to control the exhaust exit area independently of the throat of the engine?s exhaust. These are just some of the benefits that we know can occur through this system, but until it is put in a combat arena all the benefits will not be seen.
Three main prototypes have been developed and tested to install on existing fighter jet engines. General Electric developed the Axisymmetric vectoring Exhaust Nozzle (AVEN) in 1991 as the first retrofittable nozzle. It has 3-dimensional vectoring in the pitch (up and down), yaw (side to side), and thrust reversible directions (back and forth directions). Pratt and Whitney has engineered to prototypes the Pitch Yaw balanced Beam Nozzle (PYBBN) and the Spherical Convergent Flap Nozzle (SCFN). The PYBBN has a multiple redundancies system, which acts as a fail save in cases of emergency, and a faster response time that the GE AVEN design. The SCFN, is the newest model, and allows for a 20 degree pitch and yaw vectoring as well as engine reversibility capability. It also uses advanced materials to decrease the weight and cooling requirements of the thrust vectoring system.
There have been 2 main research programs within the United State military to investigate the uses of thrust vectoring within the last decade. The F-16 MATV (Multi-Axis Thrust-Vectoring) program uses GE?s AVEN design. Besides the added nozzle on the end of the engine a digital flight control system using post-stall laws for better guidance was added, this new system has been recognized as the key to post-stall flight. The parts for the nozzle are a vectoring ring, 3 actuators (hydraulics), multiaxis hinges (those that move in 2 or more directions), and some additional structural supports. The prototype adds an additional 400 pounds, which is offset by ballast tanks near the nose of the fighter. A drawback from this system occurs because the thrust vectoring takes place past the nozzle throat and prevents pressure fluctuation feedback to reach the engine controls. But due to the adjusting fore and aft translation of the vectoring ring the nozzle exit area is independently controlled from the nozzle throat. After in flight testing the results are very impressive. The AVEN design allowed a jet to maintain an 83 degree angle of attack compared to the standard 25 degrees. A maximum nozzle deflection angle of 15 degrees was achieved during standard military use and 17 degrees in after burner mode. Even more impressive was the results from mock engagements. After 182 one versus one and one versus two engagements the following patterns arose: offensively vector throttling allowed for a reduced time to the first shot at a target, reduced overshooting and other common mistakes, and allowed the fighter to at least threaten, if not engage, the wingman while attacking the primary target. Defensively the system allowed the jet to survive longer, and the possibility to make offensive maneuvers during the two versus one engagements, were typical jets try to escape. ?Thrust vectoring was very effective in our close-in combat evaluations,? said Lester Small, Air Force program manager for the MATV Project. (Ashley, 59)
The second major program is the F-15 ACTIVE, a joint NASA/Air Force program, using 2 PYBBN engines due to the fact that the F-15 is a dual engine fighter. The goals of this program is to find optimum nozzle setting for the maximum performance, investigate new air flow due to thrust vectoring, and find methods for reducing noise generated by the nozzles. The components include a divergent actuation system, a divergent synchronization ring, and an aft static structure. The nozzle utilizes the air in the nozzle region to balance forces on the front and rear side of the unit?s flap assembly. These tests have shown that this system?s multiple redundancy capability adds greatly to the safety factor of the fighter. The two engines off set from the center have allowed for new testing that could not be performed in the MATV project. Official results from this project haven?t been published, but everything indicates that the fighter?s success in this project rivals that of the MATV?s F-16.
Capt. Jim Henderson of the 422nd Test and Evaluation Squadron at Nellis AFB in Nevada said this about the thrust vectoring system, ?the bottom line is you have a greatly increased capability to survive and kill with this system.? (Ashley, 63) Thrust vectoring is a technology worth the money and ready for the next step; implementation in front line fighters. We are not the only country with this technology, the Russians have developed a thrust vectoring nozzle for their new age Sukhoi-35 fighter, which will become their front line fighter when their military budget and costs come together. It is imperative that the United State continue to provide the state of the art equipment for our servicemen. The new F-22 Raptor is slated to have this feature, but companies have developed, tested, and prepared nozzles to attach to current fighter jet engines. The greatest summation of the system is by Lester Small, MATV project manager, who said, ?vectored thrust in no panacea, it?s just another tool in the pilot?s toolbox.? Thrust vectoring is a tool that can save lives and allow America to continue its air dominance right now.
Tekst preuzet sa; http://www.electronicaviation.com/articles/Military/146
Dopuna: 06 Avg 2010 2:43
su47berkut ::@salesam
Opste poznato je to da je formulu za stelt u jednom casopisu obajvljen clanak o tome i da su najbolji americki naucnici seli i dobili F117,a SSSR je lepo rekao da je spor i da ima losu aerodinamiku.
Gde su u SSSR pogresili,nigde,a to su znali 60-tih,ali to nije za ovu temu.
Opet pominjes dobili F-117, izvini ali te ne kapiram. Amerikanci su na osnovu objavljene knjige (ne mogu da se setim imena) dosli do nekih resenja koja nisu sami mogli da nadju, a ne projektovan F-117. Rusi su mogli da pricaju sta hoce, takav avion ne bi mogao da leti bez pomoci kompjutera i tu opet dolazimo do Ruske hoces zaostajalosti ili radi ideologije ali su oni stelth avion ocenili kao Sfi.
Konkretno jel ti smatras da su Rusi mogli da naprave avion poput F-117 tih godina? Jel F-117 los avion za ono za sta je projektovan radi te lose aerodinamike i sporosti? Ako su Rusi sve znali zasto su uzimali delove od palog aviona?
Citat:ovo si ti rekao:"Da li je F-22 nepokretan avion ili je trenutno od svih serijskih aviona (neracunajuci demonstratore tehnologija) pri samom vrhu, pored Sukhoja Su-35 i onog drugog?"Evo vidis da si rekao da F22 odma iz SU35Bm i Su37, ustvari si rekao da je F22 drugi jer je SU37 demonstrator "(neracunajuci demonstratore tehnologija)".
Iskreno ovde sam stavio BM da neispadne da je F-22 najbolji i ako isti tek ulazi u naoruzanje. I ne vidim sta sam to lose rekao? Mislim da ce BM biti ispred i F-22 i T-50 po manevarskim sposobnostima, cak i ispred Su-37 za nijansu.
Citat:@Kristian_KG
Pusti ih Su27 familija i PAK FA su najgora po aerodinamici necemo vise raspravljati,a reptor je najbolji sa svojim sistemom za ispravljnje greska pilota koji ima i najstrije verzija SU27.
Zatim reptor drzi sve rekorde na svetu.
Tu ironiju sacuvaj za nesto drugo. Ovo sto navodis nema blage veze sa time oko cega raspravljamo. Izvini koji je to sistem za ispravljanje gresaka, ti nastavljas po starom, e sad da li namerno provociras ili je nesto drugo u pitanju to vec ne znam?
Citat:@Besotted
Su27 sve verzije,SU30MK svih 12 ili24 neznam koliko iimaju,MIG29 sve verzije od prve do poslednje.
Nije elektronika Bog pa da sve moze.
Svi navedeni su u stanju da urade Kobru,a nijedan amer je jos nije uradio,ali ovo je tama za PAK FA,a ne za druge avione.
Ameri koji rade Kobru su od serijskih F-22, od demonstratora X-31, VISTA, HARM, MTD. Onaj ko je taj tvoj manevar radio pre svih njih je bio Draken, a pre njega ima jos jedan avion za koji ne znam naziv.
First http://www.youtube.com/watch?v=Hax3rhqGJcQ and last http://www.youtube.com/watch?v=RJO0KzTgcMI
Da li je to po tvom ukuse je drugo pitanje ali da neduljimo posto smo vec vodili ovakve rasprave. Bilo bi lepo da nesto pogledas i van onoga sto prave Rusi pa da onda komentarises.
Kristian_KG ::OK ti kazes da nece dostici letne karakteristike su-27 familije.
Da budemo precizni poslednjih izdanaka, misleci konkretno na BM i na onaj pali Terminator nekad i nijedan vise.
Citat:Neko je ovde pricao - mislim cak vise vas koji gotivite zapadne masine da je RAPTOR manevarbilniji od bukvalno svakog aviona SU-27 familije(SU-30mk ne moze da se odrzi par sekundi pod napadnim uglom od 90 stepeni kod manevra zvono pre nego sto pocne da propada sto RAPTOR naravno moze  Ima takodje problem sa propadanjem jer su mu izduvnici 2d sa ukrstanjem itd.SU-27 nema 3d ili 2d uzduvnike tako da je odmah otpisan.SU-35BM - ne zna se koliko je manevarbilan posto nismo videli(kao da nije lako pretpostaviti)itd,itd).
To ko sta gotivi nema nikakve veze sa pricom, ja sam gotivio Su-37 izuzetno i ako je Ruski, Ok. To sto ne volim ove grbave dvosede je moja stvar. Su-34 mi je izuzetan avion, kao i stari Su-35, a i novi BM, zato preskoci to gotivljenje.
Ovo boldirano sam ja navodio nekoliko puta, i sta je tu neistina (s tim sto nisam pominjao Zvono, to si dodao ti)? Za druge ne znam da li je neko navodio to isto. Nadji snimak gde se odrzava neki MKI tako kao sto navodim pod izuzetno velikim napadnim uglom (ne mora biti bas 90*). Videces i ta propadanja koja sam pominjao (za razliku od Raptora), samo ako hoces. Jel ukrstanje nije pravilo probleme, bili piloti iskusni ili ne (te i takve mlaznice evidentno prave probleme)? Iskusniji piloti nece imati taj problem jer ih nece ni koristiti i onda dolazimo do toga da je u pojedinim momentima isto kao da ih ni nema.
Za BM ja to nisam napisao jer moze biti samo bolji od MKI-a, nikako gori. Secas se da sam govorio i da ne znam koje su to borbene prednosti koje donose prave 3D u odnosu na prave 2D, e pa ni sad to ne znam ali znam da su ove hibridne gore od bilo kojih ovih "pravih".
Citat:Ako uzmemo ovo sto si ti rekao - PAK FA nece dostici manevarbilnost SU-27 familije. Dolazim do zakljucka da ce RAPTOR i u blizoj buducnosti biti najmanevarbilniji lovac i da mu nema ravnog ?
Da i sta je tu sporno? Do ulaska BM-a ce tako biti. Ili mozda MiG-a 35 pod uslovom da dobije nekakve pokretne mlaznice (ako uopste bude imao porudzbine), a opet mozda do Tajfuna sa TVC-om, njega smo nepravedno izostavili iz price (kanari + TVC).
Danas Raptor jeste najmanevarbilniji ili to ne sme da se izjavi jer nije Ruski avion u pitanju? Do dolaska Pak-Fa ima vremena, on ce biti negde u vrhu sigurno, na kojoj tacno poziciji ne bi prognozirao jer ne znam ni kako ce stvarno izgledati na samom kraju.
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