SchorschBy the way, did anyone happen to read about the following details:
– How long was the test flight? [read about 1 hour]
– Has there been another flight since?
– Was the gear retracted? [apparently not]
– Were the flaps retracted? [don’t think so, but difficult to say]
– What was the take-off- configuration? [less than the landing config, so they moved the high-lift]
– How long was the take-off run? [I could only see a shallow climb]
SchorschIf the wing of IL-476 doesnt get redesigned, the advantage of supercritical airfoil to conventional wing is obvious.
Supercritical profiles increase the drag divergence Mach number, hence allow to cruise faster. This advantage is usually converted into a thicker profile and lower wing sweep, saving wing structural weight.
MTOW limitations due to insufficient thrust have no connection to it.
The Y-20 will have more drag than the IL76, it has higher empty weight, and is stuck with the same thrust. Someone might dust off his aircraft design textbook and check the consequences of that.
Reading this thread it sometimes feels like the blind discussing their favorite color. Many jump quickly on conclusions throwing in buzzwords like “composite” and “supercritical profile”. But only very few seem to have a clue.
Schorschcredit the Y-20 with a 10% fuel burn advantage from its modern wing
Please explain why the wing reduces drag by 10% just by being “modern”.
nowhere near your 20 ton estimate, with fairly conservative assumptions.
My number was just for representative mission. I am sure it can haul 40t, but not that far.
Pretty funny to see the empty weight figure is the same, although I would agree that 220 tons MTOW and 66 tons payload is completely out of the question with D-30 engines.
220t is off limit with current engines. That’s what I am trying to say, but nobody understands.
100t OEW is optimistic.
Why not 66t? Surely possible. But how much fuel? Payload is a design parameter, MTOW is more a result of aerodynamics and engine.
SchorschWithout even researching it I’m pretty sure it’s a lot more than 10 tons. Maybe 20?
Or 34.1553 long tons. Let’s wait for the official numbers!
SchorschA full load of fuel is roughly 10ton weight.
Are you drunk?
The IL76TD hauls 50t for 4400km.
Using the OEW and MTOW (92t and 190t), it requires roughly 48t fuels for that (assume 10% of that as reserve – these don’t scale).
10t will consequently leave 5t trip fuel, sufficient for a 500-800km hop.
Given the officially stated MTOW of 200ton and a full load carrying weight of 66 tons that will give you 56tons of cargo capacity.
Refreshing to see that some people actually take the official numbers serious …
Which sound just about right in my book given it uses composites to save weight so the load carrying capacity should be bigger than the vanilla il-76
Your book appears flawed. Maybe it mixed meters and feet.
Have you any idea about how much weight is saved with composites on other in-service aircraft? Actually, do you have any idea of aircraft design?
Schorsch1. I can’t think of a similar sized more modern (composites, wing, …) aircraft with the same powerplant having such a low capability. (I can’t think that the Chinese are so stupid to make such a fuss only for 25t.)
Again, written several times already.
The aircraft on those pictures us a test aircraft.
It is not intended for service in its present configuration.
The service aircraft will have new engines, thus drastically increasing the performance.
The payload is the difference between MTOW and OEW. The difference can be used to carry fuel or actual cargo. A good example of “MTOW restricted cargo aircraft” is the early C-5A. In case of the C-5A, it was for structural reasons.
2. You say “Your estimations”, “it is significantly larger” … please share Your thoughts, since either I’m too stupid or You are wrong, esp. if You ignore to answer to a specific question. It is not smaller and why do You calculate from the wiki-data such a low capability ?
Not at this point in public domain.
SchorschSchorsch, please !!!! 😮 😮 … simply compare the dimensions ! It has surely a wider fuselage, but overall it is surely not “significantly larger” ?
I’m not sure with what images You make Your estimations … :confused:
Deino
Do we need all these !! :rolleyes::D:rolleyes::confused::diablo::):rolleyes:?
What is your estimate on the Y-20’s empty operating weight and its MTOW?
My estimate is maybe less optimistic than those “documented” in Wikipedia.
SchorschAgreed, but could You please explain why You estimate the Y-20′ OEW to be significantly higher than the Il-76, which results in Your estimated/guessed limited margin between MTOW and OEW that it probably can only carry 20t ???
Maybe because it is significantly larger?
SchorschThe ARJ21 is an unmitigated disaster, concur. However, is it indicative of the progress and ambition to be expected from other Chinese aerospace projects? I would argue no, there are quite a number that appear to be running rather well, especially in the military field. Just as the Il-476 is (luckily) not typical of other Russian programmes, like the SSJ which (while not revolutionary) contrasts markedly with both the Ilyushin and the ARJ21.
What we currently see in Chinese industry is large amount of projects, but a lack of “finishing”. To be honest, the “last mile” (certification, entry-into-service) is usually the longest mile. For the casual observer (especially all those enthusiasts populating the internet fora) the aircraft looks finished. But actually, it isn’t.
The ARJ21 is a quite good yardstick. The fighter projects are slightly different as the rules are different. Any transport-like aircraft needs an international-standard certification, otherwise it cannot enter airspace of other countries.
I actually don’t wanna say anything negative about the Chinese (or the Russians), I just advise caution on guessing how great this Y-20 will be. It is a prototype, and investigation of past projects of similar dimension are helpful in understanding the specific challenges. Physics are similar in Europe, China, USA and Russia. 😉
SchorschBut just one question … why do You expect the capacity of only 25 t ??? It uses the same engines like the Il-76MD, it has a “similar, maybe not much improved or more modern aerodynamics” … so why s´do You expect it to fall so low in comparison to the Candid ?
Deino
Empty mass estimation.
SchorschAt what price ??? An even longer dependence, most likely again the same problems with deliveries, cost, …. see several other similar contracts or the already done Il-76/-78 contract some years ago.
All large tactical/strategic transports have one thing in common: they came out much more expensive than expected. I don’t think the Chinese version will be any different, especially as many solutions are new for the Chinese.
Even if my layman-eya can’t judge that like You, but is that necessary to be a revolulionary design ?? Like I said I probably can’t decide if the aerodynamics are much more advanced or only ‘on par’, but actuall I can’t think of performances lower or worse than the Il-76MD.
No, it doesn’t have to. It needs to do a job. Aerodynamics are just a tool. I just don’t like this bla-bla or “aerodynamically advanced” without knowing what that practically means. Military transports are by definition no efficient cruise aircraft, and each meter less field length costs a nautical mile range (at constant MTOW).,
Yes, but again, why means limited = “basically useless” ?? Especially if it offeres similar or only slightly better – as You say – performances even with the interim engines and only slightly improved airframe. Anyway I can’t think of lower performance in comparison to the standard Il-76MD, especially since it uses the same engines …
If the margin between MTOW and OEW is so limited that you can only carry 20t, it becomes basically useless. But we neither know MTOW or OEW, but one can make an educated guess …
IMO the most important aspect is the wider fuselage …
Yes, but a wide fuselage is expensive. See A400M, which compromised towards a smaller fuselage. Only few payload demand a C-17, and most of the time an aircraft flies palettes.
Not the case – certainly not the Il-76 and everything else is pretty much made by Antonov (An-124? Production line exists, but is inactive. An-70? No large scale production line available). Not for lack of effort though, they’ve been trying to acquire up to 40 new Il-76s since 2005, but have now settled for 10 used ones in the interim – that’s just how incapable Russia is of fulfilling orders. Production at TAPO in Uzbekistan has all but broken down the late-1990s, which combined with the Orange Revolution in Ukraine (which made the An-70 politically untenable) led Russia to move production to their own territory – the Il-476.
Do not underestimate the time required for the Y-20 to go into production. Chinese track record is not that stellar in this respect.
Is the ARJ-21 in service? > No.
Has flown when? > 2008
But it is … ? > … essentially a DC-9 with new wing.
So, 5 years, and that is without changing the engine half way in the test phase. The Chinese aim at a very long development schedule.
Depends – the basic Il-76 is a useful machine and does not gain a great deal of MTOW with PS-90 engines, not even in new-built, structurally strengthened form (Il-476 MTOW increase is little more than 10%).
And this MTOW-increase more or less cancels out the OEW increase. but staring at MTOW is no useful way of determing capability.
The new engines reduce fuel burn and take-off run.
So the aircraft can get out of restricted fields with more MTOW and fly further on the same MTOW. Depending on the actual payload and field, the IL76-PS90 can dramatically improve performance, and make missions possible that have been off limits with the old engines. Further, the PS90 should be less restricted in hot&high conditions.
For the time being the Y-20 is stuck with an interim engine, but more or less the OEW of the “final version”. I doubt strongly that the Chinese even intend to put it into service before the new engine is fitted. And if, rather as pubilicity stunt than due to true capability.
SchorschI suppose there is some degree of resemblance… but there are only so many ways to engineer a “T-tail”, and the British & German commercial T-tail designs were also similar.
Right so. Still the Chinese apparently encountered very similar problems. The VTP is also quite large.
For a country as large as China, with its military needs and aspirations, having heavy lift capability is vital, and it’s far better to depend on your own indigenous design to supply that need than to depend on another country.
Why?
China could by any Russian type and have it in 2 years. The Y-20 will need probably 6 years or more to EIS.
Fair enough in the case of the Y-20, still doesn’t explain the Il-476 though. If you have access to a combination of An-124s and An-70s (which Russia did, if only the political will existed) there isn’t really a niche left for the Il-476. While on paper it does sit in the payload gap between the two Antonovs, its obsolete design makes it too inefficient to justify its considerable development cost over occasionally flying An-124s half empty or An-70s with a stopover for fuel.
And why don’t the Russians push the development? There seems to be something sour. The AN-70 is sold to me as being “ready” for production. But the shear lack of orders from the now quite solvent Russia makes me think there is something not working.
With better aerodynamics it will already come pretty close to matching it though, so ‘nothing to worry about’ is a bit complacent, like Boeing saying the A320NEO was nothing to worry about (we all know how that ended).
What is so aerodynamically advanced on the Y-20? Better wing profile helps drag at design Mach number. Apart from that, I can’t see a big improvement.
Nonetheless, yes – propulsion will likely remain a disadvantage for some time, but as I said the Y-20 will probably be able to give competitive performance even with somewhat inferior engines.
I think the Y-20 will be severely MTOW-limited until it gets a new engine. Basically useless. This indicates that the Chinese aiming at a rather long test campaign.
SchorschHello Trident people!
I am looking for two pieces of information easily obtainable by anyone with some insight (which I lack – when it comes to the HS121).
First:
What is the actual fuselage diameter and hight?
Second:
Was a 7-abreast layout ever used in commercial service?
The latter is of special interest to me. I would really like to find out how they squeezed 7 people into an aircraft not wider than a B737. And to my knowledge such seating does not meet certification standards. However, maybe British rules in the 1970ies were different than FAA rules (they most likely were). Today FAA and EASA are pretty much the same except for some very small differences (ever noticed the funny “flotation devices” instead of the life wests when flying US domestic?).
SchorschI suppose hindsight is 20/20. Perhaps the Soviets were not faced with the same challenges that confronted western designers- i.e. a dense SAM network protecting the USSR.
Probably the Soviets:
– generally lacked the technology, i. e. had to do more than just a few calculations concerning radar reflexion
– the Soviet air force didn’t really have a requirement for such an aircraft
– the Soviet “tactic” usually was brute force with large numerical superiority … combat losses were anticipated and accepted
The F-117 followed the simple logic, that a single F-117 could have the combat effectiveness of 20 aircraft when used versus the correct targets. The Soviets probably didn’t bother too much on such details, most of their aircraft were pretty hard pressed delivering a worthwhile conventional punch.
SchorschIf we take a look at the Su-27 development, the bulk of the western intel knew very little of its(Su-27) capability before it appared at Paris airshow.
I mean, not its appearance but how it actually performed.
I think it is safe to say vica verca about the F-117..
They probably had a rough idea on the Suchoi 27 before it even touched ground in Paris. Limitations in Russian technology were all to apparent, and as long as the Russians didn’t leapfrog the American technology, a basic assessment usually brings one close to the actual specs.
So, in case of a Suchoi 27, basic dimensions were known.
> make a guess on gross weight (using wing area)
> make some sketches to guess internal volume
> make an estimate about the engines
> have preliminary figures on range & payload
The West knew that the Suchoi 27 was roughly comparable with the F-15.
Something hard to guess is capability of avionics. Here the West usually had no idea, especially as Russian allies did only get the second class scrap.
For Russian intelligence the job on the F117 was more difficult. And knowing that it was stealthy doesn’t truly help when you don’t know how much. I guess the F-117 was kept secret also to hide its many many shortcomings.
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