China's transport, tanker & heavy lift aircraft


tupolevtu144

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wonder if the WS-20 nacelle has thrust reversers. it would be important for short field performance and ground maneuverability.
Speaking of thrust reversers and short field performance, I wonder how the short field performance of the y-20 compares to that of the c-17. I also wonder if the thrust reversers of the y-20 can be deployed in midair as well for short field landing performance.
 

Richard Santos

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Photos of the Y-20 I’ve seen suggest y-20’s wings are simpler than the C-17’s, with smaller high lift devices and no overwing spoilers. so I suspect the short field aerodynamic performance would not be the equal of the C-17.
 
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Tirdent

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wonder if the WS-20 nacelle has thrust reversers. it would be important for short field performance and ground maneuverability.

I would expect so. More interesting is the question whether it can reverse the core exhaust too, or just the bypass stream (as is usual on high-BPR engines). Uniquely, the F117 on the C-17 has this ability, and due to its low-BPR design with bucket-type reversers, so does the old D-30KP.

Photos of the Y-20 I’ve seen suggest y-20’s wings are simpler than the C-17’s, with smaller high lift devices and no overwing spoilers. so I suspect the short field aerodynamic performance would not be the equal of the C-17.

Actually the opposite is true - the C-17 has very simple fixed-vane drop-hinge (as opposed to sliding track) flaps, while the Y-20 basically copies the Il-76 fully articulated triple-slot flap system. The difference is a bit deceptive though because the simplified flaps were the subject of extensive prior research and optimization (YC-15), but most importantly take advantage of innovative solutions.

Firstly, external blowing - the engines are positioned higher (but also further forward, to avoid inducing locally supersonic flow in cruise), so the exhaust stream blows over the flaps when extended. Secondly, as on the 787, A350 and A400M the spoilers can deflect *downward* to control the width of the slot between main wing and fixed flap vane and provide smooth camber. Although the Y-20 most definitely does have spoilers, I doubt they have this function and the engine positioning suggests there is no external blowing either.

Still, the Il-76 does quite well in terms of short field performance (though at the cost of much higher mechanical complexity), so I expect the Y-20 will be decent.
 

Xsizor

Senior Member
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I would expect so. More interesting is the question whether it can reverse the core exhaust too, or just the bypass stream (as is usual on high-BPR engines). Uniquely, the F117 on the C-17 has this ability, and due to its low-BPR design with bucket-type reversers, so does the old D-30KP.



Actually the opposite is true - the C-17 has very simple fixed-vane drop-hinge (as opposed to sliding track) flaps, while the Y-20 basically copies the Il-76 fully articulated triple-slot flap system. The difference is a bit deceptive though because the simplified flaps were the subject of extensive prior research and optimization (YC-15), but most importantly take advantage of innovative solutions.
Weren't Ukraine helping/ supplying the triple slot flap system? I read that somewhere. I expect China to have weaned itself off that arrangement.
 

lcloo

Senior Member
Weren't Ukraine helping/ supplying the triple slot flap system? I read that somewhere. I expect China to have weaned itself off that arrangement.
Yes, I read that too, years ago. Ukraine help to improve the wing design. It is more efficient than that of IL-76.

Edit- from huitong in Chinese Military Aviation.
"Assistance was sought from Antonov Design Bureau in 2008. Fitted with high-lifting devices along the wing leading and trailing edges plus six pairs of main landing wheels,
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(K/JY20A) is capable of taking off from relatively short runways, making many airfields behind the battlefield accessible. Like C-17, it may also feature supercritical wings which give the aircraft a better fuel economy thus further extends its range."
 

Tirdent

Junior Member
Registered Member
The Y-20 definitely has Antonov written all over it in many respects, but the flap system appears to have been lifted more or less straight from the Il-76. One important departure in the wing design more generally is the adoption of modern supercritical airfoil sections though, it's quite plausible that Antonov lent a hand here. In the USSR, the An-124 was the first application of this technology, roughly contemporary to the introduction in the US on the 767 and 757 (Airbus went first, with the A300).
 

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