Sukhoi PAK FA news and speculation (T-50, I-21) Part II [2008-2009]

[Spring]

Other than the Pakfa speculation, which is a bit overdone already, i would like to know what are the real issues of variable bypass technology, some posts back it was mentioned that rectangular intakes are not very compatible with such technology, then someone speculated that probably due this reason the new aircraft would get rounded intakes, comparing this with the F-23 production model.

Does the flow must be completely homogeneous?, any variance or disruption would lead to a decrease in the engine's performance, or stalling? and have this issue something to do with the probable peripheral arrange of the bypass doors?

Any pdf about the issue, it must not be about the F22/23/pakfa..etc, but about the variable bypass technology.

Any picture of a variable bypass core?

Thanks

 

[saintkatanalegacy]

this one i guess

http://www.paralay.com/stat/Bulat_12.pdf

 

[fightingirish]

This last PAK FA render is not bad...

Edit 1: I found this picture at militaryphotos.net. No original source so far!
Edit 2: Maybe it is done by Paralay, because it is on his homepage. ???

This drawing is made for the magazine "Popular Mechanics", soon there there will be article about PAK FA.
The picture is made on the basis of a photo of model of office Pogosyan.

 

[elmayerle]

Does the flow must be completely homogeneous?, any variance or disruption would lead to a decrease in the engine's performance, or stalling? and have this issue something to do with the probable peripheral arrange of the bypass doors?

It's all a matter of what inlet flow distortion your first stage of the engine fan/compressor section is designed to operate with. One aspect that sets the F118, in the B-2A, aside from other variations of the same basic engine (F101 F110) is that the first stage fan is designed to be able to deal with considerably more inlet distortion than its sibs.

 

[kcran567]

Donnage99

About the MiG-21 Bison i was just pointing out what the US pilots and others said about it being hard to detect for its size and ECM suite. I still say the PaKFa will be stealthy to an extent...but not to the high tolerances of the f-22. The Pakfa will be more of a "battlefield" practical stealth. Selected use of stealth features where critical.


you're definitely right about the high performance boresight missiles...but if you're out of medium range missiles you're still gonna have to get close enough to fire a close range IR (boresight or not) missile...and maneuver still a factor to avoid a close in missile from hitting you re plane if you can. And what if you need to use a gun as a last resort? You cant use geometry and energy unless you are travelling at a higher speed than the other guy or egressing out of the area quick.

Great image of the Pakfa...that may be what it looks like or very close to it.

 

[donnage99]

you're definitely right about the high performance boresight missiles...but if you're out of medium range missiles you're still gonna have to get close enough to fire a close range IR (boresight or not) missile...and maneuver still a factor to avoid a close in missile from hitting you re plane if you can. And what if you need to use a gun as a last resort? You cant use geometry and energy unless you are travelling at a higher speed than the other guy or egressing out of the area quick.

I was talking about closed range dogfight. Geometry and energy is what determine how your speed gonna be. Every time you maneuver, and the more aggressive maneuver you do, you increase drags, which means you lose speed. If a missile is loosed at you, you better hope to be flying at your optimum speed rather than having to accelerate back into top speed because you compromised it during your maneuvers to get a lock on. And the best way to not compromise speed is to not having to maneuver to shoot your enemy in the first place.

In term of geometry, the smaller the angle your nose (which means your direction of flight) is facing the enemy plane, the less chance you survive. Because if you are flying toward it, if the enemy loose a missile, the time of contact and time for you or your plane to react is much smaller because the speed of the missile adds up with the speed of your plane. If you are facing away from the enemy, the opposite would apply. Trying to outmaneuver a missile is pretty hopeless considering no matter how great your plane is, the best anyone can pull is around 9 g's.

 

[saintkatanalegacy]

in my experience(playing flanker 2.5), you have to be in the right place at the right time and energy in order for the missile to have a correct flight envelope. the plane itself will decide when to shoot or not since you'll have to wait for the ПР signal. also, while you can target via HMD, you still have to wait for the ПР signal even if you are already armed with a high offbore missile.

albeit, energy and pointing the nose towards the enemy are still important. moreover, being able to stay away from the enemy's bore sight is just as important. just ask the Israeli pilot who got 16 kills how important energy management is

 

[donnage99]

Not in the case of f-35's DAS, with spherical infrared optical sensors to provide lock on from any angle.

 

[F-14D]

in my experience(playing flanker 2.5), you have to be in the right place at the right time and energy in order for the missile to have a correct flight envelope. the plane itself will decide when to shoot or not since you'll have to wait for the ПР signal. also, while you can target via HMD, you still have to wait for the ПР signal even if you are already armed with a high offbore missile.

albeit, energy and pointing the nose towards the enemy are still important. moreover, being able to stay away from the enemy's bore sight is just as important. just ask the Israeli pilot who got 16 kills how important energy management is

One thing you have to keep in mind is what game-changers high-off boresight "dogfight" missiles are. With these, you can pretty much hose one off anytime its seeker locks (and even if it it can't, if it's capable of lockon after launch). We are talking about missiles that make 40+ g turns and are perfectly capable of coming off the port wing and hitting a target that is flying formation with you a short distance off your starboard wing. The HMS will tell it where to "look".

The West really got freaky about these when the Soviet Union fell, and we got to fly against Fulcrums that used to belong to East Germany. An F-16 would engage close in with the MiG and would get into a turning contest trying to bring its nose around to get a shot before the MiG did. It was expected that the MiG, with its far superior high AoA would attempt to exploit this advantage. What happened was a surprise. While the MiG would also be trying to come around, what the pilot would do is look at the Falcon and his HMS would point out the F-16 to his R-73/AA-11. The missile would be "fired" and cut across the chord of the circle, "killing" the F-16.

It's always better to have your boresight on the enemy, but it's not as important as it used to be in these days of "dogfight" missiles. The only weapon that has to have the target boresighted is a gun, and they're not terribly effective air-to-air anymore.

 

[saintkatanalegacy]

nah, flanker 2.5 isn't that adulterated as most flight sims. heck, it even comes with a 250+ page manual

and yeah, while you can lock targets with the HMS, there's still a launch authority though(as with any fighter). as with hobs missile, the wvr submodes really does make things easier except for the fact that your hands busy switching different modes. then again, that's the 90's era soviet aircrafts that has been simulated to being the closest thing you can get to the actual unit.

that said, the idea of sensor fusion and lower workload is pure genius

 

[flateric]

guys, soon you will have "Topic, formerly dedicated to PAK FA"

please more facts if you know something new
this should not be duplicate of PAK FA saga at you know where

 

[Matej]

The last post here, and hopefully the last offtopic - flight tests of the russian 5th generation fighter are under way!