New Recruit
I had my doughs but now i am fully convinced that i am talking to a donkey brain human. Can you even comprehend that i was comparing F-22 intake with T-50 and F-15 with Su-27?! are you seriously that dumb?
The Engine development is taking place and the final shape of the engine outlets are still to be finalized, in that sense it is too early to predict the IR signatures
first of all stop using this 'roman hindi'
secondly i was just negating the point which said that PAK-FA has RCS of 0.5 m^2, even EF & Rafale has a better RCS
don't know why are you on Fire
& i never dreamed of Raptor in PAF
what ever PAK-FA is, it no doubt a big problem for us
try to link the posts
Say whatever you want, but Pakistani claims of destroying entire Indian MiG-21 fleet was proved false when Wing Commander Wollen led an entire squadron of IAF MiG-21 flypast two days after the Pathankot raids.
The entire world knows about it. Too bad that the Pakistanis still continue to believe the 1965 war-time propaganda.
Anyways, continue living in 1965. No wonder, you guys are ahead of us in so many aspects.
Dont post blindly
4 September 1965 IAF MiG-21F-13 shoots downs PAF F-86E
4 December 1971 IAF MiG-21FL "C1111" FltLt Manbir Singh shoots downs PAF Sabre F.6
6 December 1971 IAF MiG-21FL FltLt Samar Bikram Shah shoots downs PAF F-6
6 December 1971 IAF MiG-21FL shoots PAF CC-130
12 December 1971 IAF MiG-21FL "C750" FltLt Bharat Bhushan Soni shoots PAF F-104A
12 December 1971 IAF MiG-21FL FltLt Niraj Kukreja shoots PAF F-104A
12 December 1971 IAF MiG-21FL SqnLdr Iqbal Singh Bindra shoots PAF F-104A
16 December 1971 IAF MiG-21FL FltLt Samar Bikram Shah shoots PAF F-6
17 December 1971 IAF MiG-21FL A. K. Datta shoots PAF F-104A
17 December 1971 IAF MiG-21FL Samar Bikram Shah shoots PAF F-104A (damaged)
http://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-21#Indo-Pakistan_1971_war
Defunct Humanity: PAK FA first flight
The way the exhausts are designed, rear aspect IR and RCS signatures will doubled or even tripled from front. Not good. Dead meat for the Raptor.
Exhaust nozzle convergent coupled with throttle setting control thrust. Everything on a body create its own RCS signature and contribute to the overall RCS value of the body. The convergent-divergent mechanisms of an afterburning turbojet engine are no exceptions, if anything, they are the major RCS creators of the rear aspect.
Take a look at 'iris' style exhaust convergent-divergent nozzle above. It is called 'iris' because the mechanisms works the same way the human eye controls its pupil opening. Look at all the 'feathers' and the gaps between them. Those are corner reflectors and I have explained plenty enough here on how dangerous corner reflectors are to designs intending to be radar LO.
Now look at the F-22 exhaust convergent-divergent mechanisms above. They are simpler in designs and because there are less mechanical 'doodads' such as actuators and 'feathers' the F-22 exhausts are far less RCS contributors than exhausts with the 'iris' convergent-divergent exhausts.
The downside to the F-22's exhaust mechanisms is that it restrict thrust vectoring to 2D, whereas with the 'iris' style, the exhaust TV can be 3D, provided there are sufficient clearance between nozzles, which lead us to the controversial subject of design philosophy, specifically engine placements. Wide area engine placements have advantages and disadvantages. Personally, I have never been a proponent of wide area engine placements. The argument here is that for any reason, from bird ingestion to battle damage to 'Acts of God', in the event of a catastrophic engine failure that result in an engine explosion, the other engine would be somewhat protected. Given the fact that the airframe area between the engines are not empty but contain fuel, wirings and assorted mechanical items, an exploding engine will create enough collateral damage to render the aircraft unflyable anyway.
In the event of a non-exploding engine failure, widely spaced engines will create asymmetric thrust that can send the aircraft into a flat spin, which can be nonrecoverable. The combination here is speed, altitude, attitude and how far apart are the engines that the resulting asymmetric thrust will send the aircraft into a flat spin. An extreme example of asymmetric thrust is the C-17A Engine-Out Compensation System (EOCS) software upgrade to the aircraft's FLCS during take-offs and landings. For EOCS, the critical engine is the most outboard one on each wing if its companion outboard engine on the other wing fail. The software upgrade, upon sensing engine failure, would command a rudder deflection to compensate for the inevitable yaw (lateral) movement by the aircraft.
AOPA Online: AOPA Pilot's "An Invitation to Fly" - Beyond the Private
Fighter aircrafts with multiple engines do not have as wide engine placements as multi-engined transports, nevertheless, asymmetric thrust is still a potential problem for pilot training. The F-14 and F-15 have wider engine placement schemes than the F-18. The wider the engine placements the higher of some energy loss when there is thrust. Any mechanical engineer will tell you that it is better to have thrust as much inline with the main longitudinal axis of the body as possible. It is necessary that thrust be in parallel, but the closer to the central axis, the greater the concentration of their combined thrust to the longitudinal axis, the more energy efficient the TV system. The downside is that the closer the engines are together, there will so little room for movement that 2D vectoring is the only option.
3D vectoring require more complex flight control laws -- IF -- the desire is to automate the thrust vectoring. Automation require the removal of some of the decision making process from the pilot, which is NOT always a positive. The US have done extensive testing on the integration of propulsion into flight control laws, of which the C-17A EOCS is one deployed example, here is the history...
Propulsion Control of Airplanes
NASA - NASA Dryden Fact Sheet - Propulsion Controlled Aircraft
Essentially...If we have engine failures, there is still a good chance of recovery and survival via flight control surfaces, aka 'dead stick' landing as UA 232 demonstrated...
Deadstick landing - Wikipedia, the free encyclopedia
But what if the aircraft loses some of its flight control surfaces, that is where PCA enabled flight control laws can help. Thrust vectoring works on similar principles as PCA but it is about the incorporation of DELIBERATE off-axis thrust not to recover a damaged aircraft but to radically enhanced its flight regimes. So asymmetric thrust can be exploited to good ends.
The PAK-FA's wide engine placements allows 3D vectoring, however, we do not know the extent of TV automation. Is the pilot allowed individual nozzle vector controls? Now that would remove a lot of mathematical complexity from the flight control laws but would transfer the burden to the pilot. After all, what good in having a feature if you do not know how or allowed to use that feature? Remember UA 232 above where the pilot had to manipulate the throttles himself. This mystery alone begs us to wonder how does Sukhoi view the pilot. Is he a 'killer' first and 'flyer' second? Or would the TV training and operation be so intensive that he would be so busy working the nozzles that he can lose situational awareness and lose the fight?
3D vectoring is best when there is so little aerodynamic forces to exploit that in order to change aircraft attitude, an alternate force is required, this would be at very low airspeed, so low that even if there is any advantage to be gained over the F-22, the F-22 would have to be either battle damaged or at so low an altitude that the F-22 pilot has next to no room to maneuver. The Soviets/Russians do not have a good history of avionics and ergonomics. We knew that even before the Soviet Union collapsed.
Do not be gullible and impressed by that airshow 'cobra' maneuver. It was done with extraordinary airmanship acquired through years of flight experience and natural abilities. That is not how we want our air forces. We want an efficient combination of high flying capabilities and human instincts now. The American philosophy is -- make the aircraft do the flying as much as possible so the pilot can be a 'killer' primary and 'flyer' secondary. When the aircraft exceed maneuvering requirements just through aerodynamic exploitations alone, TV capability is gravy and having 2D only allow some pilot control and some automation without overly complex flight control laws. This is like creating one hundred above average airborne killers in one year instead of ten excellent ones in two years.
Raptor is a classification of bird...
Bird of prey - Wikipedia, the free encyclopedia
Dead meat for the Raptor, baby...
