China's indigenous bomber program
- Thread starter Totoro
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sumdud said:
Apparently the production is still ongoing as we speak, with the latest version h-6h airplanes first delivered in 2004. I'm just not sure how many are produced, i'm suspecting the numbers are pretty low, perhaps as few as one a month. I am sure PLAAF also needs to replace older ones from the 60s too, some of those airframes must be used up like hell so i don't really see the total number of H6 is service to increase.
But, here's the thing. The specifications on the h6 are all over the place. I checked all over the net, besides the figures offered here at sinodefence, i compared the original tu-16 specs - and it seems h6 is even more inferior to 50s/60s russian tu-16. I am guessing the biggest blame there goes to chinese engines, being huge gas guzzlers, like you said. specs for tu-16B (which seems to be most comparable with h-6) go up to 12 tonnes max payload or 6 tonnes with maximum amount of fuel for 1800 km combat range. Other versions like tu-16c can deliver 4,5 tonnes to over 2400 km. And that's all done with fairly old turbojet engines.
It is therefore clear that a turbofan, even a low bypass one (perhaps ws-10a?, it has little less dry power but the savings in fuel should still be considerable) would improve payload/range immensely, let alone a high bypass engine. Perhaps they should just rip off the system and engines off a B737 and put em up on the h6, it'd still be miles superior to existing engines.
Seriously though, wings look high enough to me to carry the engines on short pylons underneath. I just don't know how much work that'd require, redesigning the wing root, since whole point is not to have to go through long development cycle.Right now, some 33 tonnes of fuel are carried to achieve the mentioned 1800 km combat range. Sounds like an awful waste of fuel.
There is several mentionings that in the seventies Chinese installed Spey turbofans for testing purposes onboard H-6s. I don't know what was the results of these test nor ever seen any picture of the engine arragment (so i cannot say wheter it was a blended like the orginal engine configuration or more of wing mounted) or about the project in general which means this rumours aren't 100% thurstable least not to me.
The main site also have a section for cancelled bomber projects which were in effect a H-6 type of hull fitted with underwing Speys (six in total). These projects like so many other chinese aircraft pograms were cancelled and nothing came from them. Also when searching material concerning the Chinese first indegenious turbofan engine, WS-6 (note, not WB-6), it was also mentioned to be possiple engine for future bomber project but i have nothing more about it.
It's quite sad as so many promising and interesting chinese aircraft programs have been cancelled for varios reasons ...well we all can still dream, right
The main site also have a section for cancelled bomber projects which were in effect a H-6 type of hull fitted with underwing Speys (six in total). These projects like so many other chinese aircraft pograms were cancelled and nothing came from them. Also when searching material concerning the Chinese first indegenious turbofan engine, WS-6 (note, not WB-6), it was also mentioned to be possiple engine for future bomber project but i have nothing more about it.
It's quite sad as so many promising and interesting chinese aircraft programs have been cancelled for varios reasons
...well we all can still dream, rightThat B737 idea isn't so crazy, actually. Lets take two B737 models for comparison. First is b737-300, model that first flew in 1984, so early 80s tech. Second is b737-700, first time flew in 1997, so its mid 90s tech.
Their length is very comparable to h-6, boeing 300 has 29 meter large wingspan while boeing 700 has same wingspan as h-6. Furthermore, boeings have larger, wider bodies, bigger tail section, bigger engines mounted on pylons, etc. Now, of course it's impossible to accurately guess drag but it's safe to say that boeings, while having considerately bigger frontal surface made drag, have less skin friction drag, less induced drag, better shape overall. For the sake of this post, i'll assume drag levels are similar.
To make long story short: B700 has like 102% maximum range of H-6 while carrying 500% bigger payload. Its empty weight is same as H-6 but it achieves the said range carrying just some 66% of the amount of fuel H-6 does for its range. Engines provide 89 kn thrust, quite comparable with h-6's 93 kn, i'd say. If one could use same level tech engines on h-6, that's 15 tonnes of payload delivered 6000 km away. No matter how you look at it, thats at least 2000 km combat range, with nice reserve to fly faster if needed. Just for extra information, B700 normally uses up 2070 kg of fuel per hour at normal flight conditions for such longest range scenario.
But lets say such mid 90s tech engines just isnt available to china. B300 weighs 33 tons, or little under 4 tonnes less than h-6. its max range is 80% of that of h-6, but it carries 14.5 tons of payload to that range. Knowing that it carries 16.3 tons of fuel, one can calculate that it'd need 20.35 tons of fuel for h-6's range. That'd lower its useful payload to just over 10 tons, but that still beats h-6's figure of mere 3 tons. For comparison, b300 engines use 2250 kg of fuel per hour at normal regime for max range.
Even old B737-200, which first flew in 1967 and its engines are mid 60s turbojets and not turbofans has 4900 km range for some 12.3 ton payload and its engines use little over 2800 kg of fuel per hour for that max range.
Conclusion is, of course, same as in the earlier posts (only then i was just talking out a gut feeling and now i made a little bit more precise guestimate) - just by using different engines h-6 can be turned into a great platform, carrying 10 tons (sinodefence says 9 tons is max, perhaps structure cant support more?) to at least 2000 km away, perhaps as far as 2500 km depending on the flight regime. 3 tons could be delivered to over 8200 km distant place (ferry range), or like 3000-3500 km combat range. Pretty impressive figures and definitively enough for a stop-gap measure plane until true indigenous, next gen bomber flies.
Their length is very comparable to h-6, boeing 300 has 29 meter large wingspan while boeing 700 has same wingspan as h-6. Furthermore, boeings have larger, wider bodies, bigger tail section, bigger engines mounted on pylons, etc. Now, of course it's impossible to accurately guess drag but it's safe to say that boeings, while having considerately bigger frontal surface made drag, have less skin friction drag, less induced drag, better shape overall. For the sake of this post, i'll assume drag levels are similar.
To make long story short: B700 has like 102% maximum range of H-6 while carrying 500% bigger payload. Its empty weight is same as H-6 but it achieves the said range carrying just some 66% of the amount of fuel H-6 does for its range. Engines provide 89 kn thrust, quite comparable with h-6's 93 kn, i'd say. If one could use same level tech engines on h-6, that's 15 tonnes of payload delivered 6000 km away. No matter how you look at it, thats at least 2000 km combat range, with nice reserve to fly faster if needed. Just for extra information, B700 normally uses up 2070 kg of fuel per hour at normal flight conditions for such longest range scenario.
But lets say such mid 90s tech engines just isnt available to china. B300 weighs 33 tons, or little under 4 tonnes less than h-6. its max range is 80% of that of h-6, but it carries 14.5 tons of payload to that range. Knowing that it carries 16.3 tons of fuel, one can calculate that it'd need 20.35 tons of fuel for h-6's range. That'd lower its useful payload to just over 10 tons, but that still beats h-6's figure of mere 3 tons. For comparison, b300 engines use 2250 kg of fuel per hour at normal regime for max range.
Even old B737-200, which first flew in 1967 and its engines are mid 60s turbojets and not turbofans has 4900 km range for some 12.3 ton payload and its engines use little over 2800 kg of fuel per hour for that max range.
Conclusion is, of course, same as in the earlier posts (only then i was just talking out a gut feeling and now i made a little bit more precise guestimate) - just by using different engines h-6 can be turned into a great platform, carrying 10 tons (sinodefence says 9 tons is max, perhaps structure cant support more?) to at least 2000 km away, perhaps as far as 2500 km depending on the flight regime. 3 tons could be delivered to over 8200 km distant place (ferry range), or like 3000-3500 km combat range. Pretty impressive figures and definitively enough for a stop-gap measure plane until true indigenous, next gen bomber flies.
MIGleader
Banned Idiot
So the key issure is a new engine? well its both harder and easier than it looks. China in the 1990s attemted to develop a large transport airframe with airbus and boeing. it was rumored(cant remeber where) that the airframe would also serve for a bomber.
the spey is 1970s technology, and is not viable solution today. airbus's rolls royce Trent 900 engine(still under development) is a good choice(as are hundreds of other commercially available jetliner engines). two of these is adequate to power an intercontinental flight, no extra engine pylons are needed. but the engine is huge in diameter, and would require extensive(i mean years of) modifications to the h-6.
another choice is GE's CF34-10A engine, already powering the arj-21. 18500 kg of thrust. four might be needed
so its pretty much a compromise between size and power.
the spey is 1970s technology, and is not viable solution today. airbus's rolls royce Trent 900 engine(still under development) is a good choice(as are hundreds of other commercially available jetliner engines). two of these is adequate to power an intercontinental flight, no extra engine pylons are needed. but the engine is huge in diameter, and would require extensive(i mean years of) modifications to the h-6.
another choice is GE's CF34-10A engine, already powering the arj-21. 18500 kg of thrust. four might be needed
so its pretty much a compromise between size and power.
engine definitely is and always will be one of the biggest problems for the Chinese aviation industry (much larger than the so called weakness in electronics). I think a derivative of WS-10A could be used for a future bomber. Considering that the core of the engine used for F-16 and B-1B are very similar, I think it's definitely do-able.
MIGleader said:
Sad thing is - even speys would be better that what h-6 fleet is using now.
But even those are not really backward engineered properly and china bought used ones from UK for jh-7s. When hearing such things it really makes me doubt the ws-10a is gonna be ready anytime soon.But lets assume china does get a good turbofan. Should it redesign the wing so the new engines are put in the place of old turbojets, in the root wings? Obviously, itd be much larger housing, requiring some extensive wing redesign. Should the wing be redesigned so the root engine housing is thrown away, and fully straight wing is used, with a pylon for the turbofan hanging underneath the wing? Or, no matter how weird it sounded, should the old engine be thrown out but the wing with the housing should be left intact - perhaps just filling out the housing with extra fuel - all the while the new turbofan is hung underneath the wing? It'd mean more drag, absolutely, lower max speed, but i have a feeling the extra efficient engines would still make it worthwhile. Advantage is that the wing would require least modifications, basically just rewiring the electronic and fuel system so they connect to the underwing pylon instead od wing root.
another intersting question - just what is the diameter of h-6 bomb bay and, even more importanly - how long is the bomb bay? With more efficient engines, less space used up for fuel, perhaps the bay could be lenghtened so missiles could be stored interally, lowering drag and making up for the extra drag suffered by underwing engines?
As for arj program helping the bomber program - that crossed my mind too. the mentioned engine provides 82 kn of thrust, not quite the same as the existing engine's 93 kn max thrust but comparable enough. With greatly decreased fuel consumption (less weight) and use of newer alloys (sprinkled with some composites where cheap to apply) they could do the job, just two of them.
BUT. That's a GE engine. American. To my knowledge, it wont be produced in china but it will be shipped to china, only to be installed on the produced planes. And we know china's backward engineering capability when it comes to turbofans is pretty lousy. I'm starting to think that, right now, until a proper indigenous turbofan is ready (is china even working on high bypass turbofans? ws 9 and ws 10 are both low bypass) it would be a safer bet to go for a prop engine. it'd kinda waste the existing wing but... if enough power can be gained from it - why not? Can't be less fuel efficient than what's on h-6 now.