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Bash the Pak-Fa thread

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I like it.  If they can get it to work and into serial production.  It's just not as stealth optimized, especially from the rear aspect as the F-22 and F-35.  They also need to get the new engines for it working and into production.

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"Not as stealth optimized" is another way of saying "not compromised for stealth".

 

AFAIK, the Izd. 30 engines will complete rig-testing this coming year. 

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Someone on SA used the phrase "Man-pack the Fagot launchers" like three years ago (and not as a joke), and I still giggle about it.

That reminds me of the time my highschool chemistry teacher said "Kids, be sure to grease your stopcocks."  Much giggling ensued.  

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The test models are using AL-41Fs, which IIRC are roughly comparable to F120s, but production models will use the izdeliye 30, which is supposed to be some super-duper engine.

 

AL-41F1, which is a ginned-up AL-31.  Original AL-41F was the engine intended for MiG 1.44.

 

izd. 30 will be the F120 equivalent with variable bypass ratio.  The current engine is more like an F100-PW-132 equivalent (only with a much higher BPR).

 

If Pratt and Whitney were to make a moderate bypass ratio version of the F119 with a circular nozzle, it would put all existing fighter engines to shame including the next-generation Russian and Chinese designs.  Sadly, the F135 is downrated for export.

 

Sukhoi will have to convincingly demonstrate that PAK-FA requires less cost and man-hours of maintenance to keep flying than a flanker to make it attractive to export customers.  IMO, that's likely to be the biggest weakness.

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......

Sukhoi will have to convincingly demonstrate that PAK-FA requires less cost and man-hours of maintenance to keep flying than a flanker to make it attractive to export customers.  IMO, that's likely to be the biggest weakness.

Well, they are building a jet for specific country airfocres, not Air Forces for a jet. Same thing with Armata, i guess.

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Thank you for the clarification.

 

You're welcome.  Now if we could only convince the Russians to adopt sensible designation schemes for all their stuff.

 

Well, they are building a jet for specific country airfocres, not Air Forces for a jet. Same thing with Armata, i guess.

 

So?  Every air force is going to want reasonable maintenance hours and costs on a fighter.  The SU-27 was an export success in spite of its engine TBO.  Export customers tolerated poor engine TBO because it was such a monstrously capable aircraft, not because they restructured to make engine TBO somehow irrelevant.

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Hmmm... so I'm supposed to find something wrong with the PAK-FA?  Um, I'll try I guess.

 

 

1)  It will probably be expensive to operate, and the engines will probably require a lot of maintenance.  This is basically an endemic problem with Russian jet engines.  If you compare the 117S to the F100-PW-229 (similarish class engines), you'll see that the F100 has a slight edge in power density, the 117S a slight edge in total thrust and efficiency, and the F100 utterly stomps the 117S in engine life.  The overhaul intervals for the F100 are about the same as the total lifespan of the 117S.

 

Unless Russian gas turbine engine design paradigms completely change overnight with the fancy new engines the PAK-FA is getting, it's going to cost more to operate it than a comparable Western-engined type.

 

2)  It's not as stealthy as a JSF or raptor, according to USAF and Sukhoi numbers.  Are they apples to apples figures?  Probably no way in hell are they, but the figures given show the JSF and raptor with an RCS three to four orders of magnitude smaller than the PAK-FA.  Given that, it seems fair to generalize that it's just not as sneaky.

 

3)  It probably will lack the SU-27's monstrous sustained turn performance.  The wing aspect ratio is not favorable for sustained turns.

 

4)  It will probably lack the SU-27 family's monstrous range.  The PAK-FA's internal weapons bays are enormous, so I have a hard time believing that they've somehow found as much room inside the thing for fuel as they did on the flanker.

 

5)  It will probably have the typical Russian "good enough" approach to flush-riveting.  This will look shabby at airshows and attract ridicule.

 

6)  The leading edges of the aircraft are made of composites, so any stripped-down, unpainted record-setting aircraft will look like a silly yellow traffic cone instead of a shiny aluminum spaceship.

 

7)  It sort of looks like a YF-23, and will inevitably cause Black Widow II fanboys to open their yaps about how much better that plane was than the YF-22.

 

 

 

In ascending order of importance, of course.

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To its' advantage, the T-50 has LEVCON's and controllable tails vs. the Su-27.

 

The SU-27 has leading-edge flaps:

 

Sukhoi_Su-27SKM_at_MAKS-2005_airshow.jpg

 

I'm not entirely sure what the PAK-FA's combination of LEVCONs and leading edge flaps can do that just the leading edge flaps can't do:

 

Sukhoi-T-50-PAK-FA-KnAAPO-2S.jpg

 

Possibly something to do with air intakes?  The air intakes seem to be integrated with the LERX, like on an F/A-18.  The other possibility is that they're scheduled with the flight control system to lower AOA during cruise flight or something.  Leading edge extensions are a bit like canards; they're very useful during tight turns because the vortices they create delay flow separation over the main wing.  However, if they do this during cruise flight they're just making drag.  The ability to tilt the LEVCONs up and down may get the best of both worlds.  I've heard nothing definitive.

 

AIUI, all-moving vertical surfaces are for stealth, not aerodynamic reasons.  They're actually slightly less efficient, aerodynamically, and much more challenging structurally because all the structural loads from the tail are going through the little stick it pivots around on.  Presumably they would give better yaw authority at transonic and supersonic speeds for the same reason that all-moving horizontal stabs do... but why you would need that I don't know.

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