When we say 2D TVC, we mean like the F-22's square 2D TVC that's beneficial to your IR signature.
In contrast to a normal circular nozzle, square nozzles could conceal the exhaust's IR signature better, but they're much heavier.
Chinese Engine Development
- Thread starter jackbh
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In contrast to a normal circular nozzle, square nozzles could conceal the exhaust's IR signature better, but they're much heavier.
manqiangrexue
Brigadier
I have no doubts about that.
What I was asking is whether the 3,5000lbf a figure that represents the F119 with rectangular nozzles or the base figure before the rectangular nozzles are added? Do we know this for certain?
35,000 lbf = 156 kN. That means with rectangular nozzles on.
The 2D concept is basically to hide the nozzles from radar so includes physical changes that inhibit or worsen 3 dimensional vectoring. It trades efficiency and thrust for stealth. All TVC is a trade off of thrust for maneuverability. But 2D is a further compromise of that for stealth.
manqiangrexue
Brigadier
That is going by the assumption that it is 10% more with them off. I'm asking if there is solid evidence for this assumption or if we actually don't know whether the 156kN figure was given as the core performance of the engine before the 10% reduction or if it is a system performance including the rectangular nozzles?
The 35,000 lbf figure is given by Pratt and Whitney with nozzles on.
Nobody knows for sure the figure without the nozzles.
The huge 10%+ losses you’re stating is for the experimental Soviet flat nozzles, the production F119 nozzle losses aren’t anywhere that severe and in the neighborhood of 5% compared to an ideal round nozzle. And if you read interviews from even Russian sources, they agree that a fully developed flat nozzle can be made to be that efficient too. An F119 with round nozzle has thrust of about 37,000 lbs so not much higher than 35,000 lbs with the current nozzle.
While the thrust efficiency with a flat nozzle is reduced, with the F119 nozzle specifically their shape also helps reduce boat tail drag and turbulent flow compared to a round nozzle for two-engine setups.
You cannot change physics.
I have never seen that 5% number for 2D vectoring. If it were true then it follows that the 3D version must be even better.
So at that point why not equip every aircraft with 3D TVC since you are only losing 2 or 3% thrust?
I see none of that in the real world.
An F119 FSR with first hand knowledge disagrees with you applying the losses from a Soviet/Russian test flat nozzle as a blanket statement for all flat nozzles.
manqiangrexue
Brigadier
OK that's what I was asking if it's certain that they were giving a figure for the intrinsic power of the engine or the power it provides as a full system including the flat nozzles. I haven't seen the language for the source of this power claim so I don't know; it might be worth thinking about if the language was not fully clear.
Then of course, there's the comment just above mine doubting the 10-15% altogether, which is plausible since we're going from a rudimentary Soviet prototype to a fully mass-produced American design so improvements shouldn't be a surprise.