Chinese Aviation Industry
- Thread starter FriedRiceNSpice
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The highlight was and still is my question or doubt of your intention. It seems you have an habit of dismissing important difference when it comes to Chinese tech. The "meta material" was the first one I noticed, this copter is the second.
Ka-22 cruise just as an an-12 without the need of rotors. This Chinese copter must has the rotor rotating to cruise. V22 is move similar to ka22 in cruising mode. Why not call v-22 just same same as ka-22? It really depends on how one cut the pie. But you always cut it in a certain way.
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I'm not interested in nationalistic tendencies one way or another - although I'm a bit of a Russian aerospace fan, I make a point of not letting any bias cloud my technical judgement. You can choose to read between the lines, but I can't be held accountable for what you find there, as I try not to insinuate anything in my posts. No skin off my nose.
Ka-22 cruise just as an an-12 without the need of rotors. This Chinese copter must has the rotor rotating to cruise. V22 is move similar to ka22 in cruising mode. Why not call v-22 just same same as ka-22? It really depends on how one cut the pie. But you always cut it in a certain way.
Because the V-22 (or the tilt-rotor in general) is unequivocally a distinct concept that uses the same rotors for both propulsive and powered lift purposes - functions that are strictly segregated on both the Chinese demonstrator and the Ka-22. You could have made an argument about the S-97 Raider and I would have, with some misgivings due to the *total* absence of fixed wing lift, been inclined to agree, but tilt-rotors are markedly different in basic function.
That the Ka-22 completely unloaded the lift rotors at high speed whereas the AVIC subscale test bed does not is almost certainly a question of available technology and development priorities. With the airfoil sections of the 1950s, continuing to rely on a lift contribution from the rotors in cruise would probably have precluded the Ka-22 from going appreciably faster than conventional helos of the day due to lift loss and drag rise from shock wave effects on the advancing blades. The modern supercritical sections which have since been developed make that vastly more tenable nowadays, to the point that Sikorsky's approach does away with the fixed wing altogether - a move which dramatically improves hover performance as there is no obstruction of rotor downwash. If we view S-97 to Ka-22 as a continuum, the AVIC demonstrator sits halfway in between in terms of the trade between hover efficiency & cruise performance (the fact that the Ka-22, due to its ancient 60 year old aerodynamics, was probably no faster not withstanding).
Whereas the Ka-22 and the Chinese demo can be considered variations of the same basic theme (albeit separated by several decades and shaped by the contemporary state of technology), the V-22 is just a different beast altogether.
BTW, speaking of downwash, I suspect that's what "discharge" refers to - though not from the rotors, but the wing in high speed flight. Rotor blades moving through this area encounter a lower than free stream flow incidence, making it more difficult for them to generate lift. It makes sense to have the blades sweep backwards through this area as at speed they will probably be unable to contribute much lift anyway due to retreating blade stall, leaving the advancing blades to do their thing in "clean" air.
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Colonel
Hmm... but the test model is essentially a helicopter and the Ka-22 and V-22 are not so.
Both the Ka-22 and the V-22 takes off like a helicopter and then cruise in level flight as a fixed wing aircraft.
The test model is essentially a helicopter from takeoff to level flight, just like the S-97 is, which I would see evolved from a generic helicopter rather than a Ka-22 type of aircraft.
Another thing is the aerofoil section of the test model is just a fraction of the size of the wing of a fixed wing aircraft. To me, this together with the fact that it's missing of the control surfaces of a fixed wing aircraft qualify the test model as a helicopter / rotorcraft, just like the S-97 is.
I think the blades are turn backwards to reduce reaction force from the wing (at ALL speed) to increase efficiency. Retreating blade stall is a inherent helicopter speed problem at higher speed, even without the obstruction of airflow through the main rotors.
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Some new information has come to light on the CRAIC C929 Sino-Russian widebody airliner project over the past weeks.
Summary & analysis of dimensional data released by Chinese and Russian participants:
Report on the hike in thrust spec for the engine RFP, indicates MTOW might have increased up to 245t now (even so, out of more typical departure airports, 78klbf per engine would be good for more than that):
Responses to the engine RFP received from 7 (!) manufacturers:
Big eyebrow raiser there - it means there might be more than one Chinese submission. Unless it's a en error and there were really 7 *engine proposals*, with at least one of a lower number of manufacturers having offered several design options... but the first sentence is pretty unambiguous at face value.
RR and GE are safe bets as having submitted proposals based on the three-shaft Trent 1000 TEN & two-shaft GEnx respectively, and I can think of two subsidiaries of Russian UEC which might be expected to enter competing bids. One is obviously Perm/Aviadvigatel (responsible for the PS-90A & PD-14) with the two-shaft PD-35 which has been associated with the CR929 for some time now. The other is Kuznetsov, who developed the losing competitors to the PS-90A, had a Trent 800 class engine in the works when the USSR collapsed and tested the NK-93 UHB recently. Based on their prior experience, Kuznetsov's design will likely be either a three shaft or GTF architecture - they previously proposed such engines in the 30tf ball park as the NK-65 and PD-30.
So who are the other three? Ok, perhaps P&W (who before were widely expected to pass) pitched in with a widebody-sized GTF after all, and it is possible that Ivchenko-Progress of Ukraine (manufacturers of the most powerful high-BPR engine built in the Soviet Union, the D-18T) gave it a shot. But unless *both* these surprise entrants threw their hat in the ring or the article actually means proposals where it says firms, there might be two Chinese widebody engine projects brewing.
Summary & analysis of dimensional data released by Chinese and Russian participants:
Report on the hike in thrust spec for the engine RFP, indicates MTOW might have increased up to 245t now (even so, out of more typical departure airports, 78klbf per engine would be good for more than that):
Responses to the engine RFP received from 7 (!) manufacturers:
Big eyebrow raiser there - it means there might be more than one Chinese submission. Unless it's a en error and there were really 7 *engine proposals*, with at least one of a lower number of manufacturers having offered several design options... but the first sentence is pretty unambiguous at face value.
RR and GE are safe bets as having submitted proposals based on the three-shaft Trent 1000 TEN & two-shaft GEnx respectively, and I can think of two subsidiaries of Russian UEC which might be expected to enter competing bids. One is obviously Perm/Aviadvigatel (responsible for the PS-90A & PD-14) with the two-shaft PD-35 which has been associated with the CR929 for some time now. The other is Kuznetsov, who developed the losing competitors to the PS-90A, had a Trent 800 class engine in the works when the USSR collapsed and tested the NK-93 UHB recently. Based on their prior experience, Kuznetsov's design will likely be either a three shaft or GTF architecture - they previously proposed such engines in the 30tf ball park as the NK-65 and PD-30.
So who are the other three? Ok, perhaps P&W (who before were widely expected to pass) pitched in with a widebody-sized GTF after all, and it is possible that Ivchenko-Progress of Ukraine (manufacturers of the most powerful high-BPR engine built in the Soviet Union, the D-18T) gave it a shot. But unless *both* these surprise entrants threw their hat in the ring or the article actually means proposals where it says firms, there might be two Chinese widebody engine projects brewing.
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Not surprising at all, it has been known for some time that one is cj-1000, the other being ws-20/sf-a. CJ-1000 is the target, SF-A is the fallback.
I think you're confusing the C929 (245t widebody) with the C919 (75t narrowbody)... a mistake which I probably invited by not calling it the CR929 - sorry!
Suffice it to say that there's a factor of 2.5 - 3 in terms of engine thrust between the CJ-1000A/SF-A and the engines in question here!
Suffice it to say that there's a factor of 2.5 - 3 in terms of engine thrust between the CJ-1000A/SF-A and the engines in question here!
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The would-be engine for the CR-929 has been speculated to be the chinese CJ-2000 or the russian PD-35, there are also western engine proposals.
Well, the S-97 has elevators & rudders, as do the Ka-50/52 (rudder), UH-60 as well as AH-64 (elevator). More importantly, so does the model of the full-size Chinese project that taxiya associated with this demonstrator (M-shaped empennage with 4 aerodynamic control surfaces).
Is none of these a helo now? See the problem with your definition?
If it comes to that, I like to think I have a pretty good eye for details, yet in my opinion the resolution of the photos is too low to tell whether the test bed does or doesn't have aerodynamic control surfaces in the first place. Is that in the text somewhere?
Not sure what you mean here - by reaction force of the wing are you referring to the effect of rotor downwash obstruction by the wing? If so, why would it make any difference to this effect whether the blade is advancing or retreating?
Never claimed RBS was related to obstruction by the wing. If you already lose most of the lift on the retreating half of your rotor discs (that's the primary reason why you provide two counter-rotating discs in the first place) however, it's not a smart move to also penalize the advancing halves by exposing them to the full downwash over the wing. Best to give up the retreating blades as a bad job at high speed and focus on providing the advancing blades with the best possible conditions for lift generation.
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