China miliary plane design
- Thread starter wmdco
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eecsmaster
Junior Member
in other words, Pakistan. Who else operates F-16s and are on good footings with the Chinese?
As for Skyhawk and the Lavi connection, Skyhawk, have you ever SEE the original J-10? I don't think you have.
As for Skyhawk and the Lavi connection, Skyhawk, have you ever SEE the original J-10? I don't think you have.
Wingman
Junior Member
Chinese domestic aircraft design ability is improving. Before they could only copy, then they mod other planes, then they design their own planes with help from foreign engineers, now they are moving on to complete domestic designs. The most "domestic" planes that came out like JH7 and K8 are not cutting edge but it's an ok start considering Chinese engineers are just starting to design their own stuff, they would play safe and not come up with anything too radical. As for how far they can go let's just wait a couple years and see how the JXX turns out
China's first indigenous fighter, the J-12, didn't resemble anything at all. Its a strict day only fighter using one of the two engines used on the J-6. It does basically follow the fifites style design with the open inlet but then so does a lot of fighters.
The J-8 only vague resembles the MiG-21 in layout. Structurally, the plane is quite different. Two engines, round intake with nose splitter, and the radar design was totally indigenous as it didn't really resemble any Russian radar at all, not the one used in the MiG-21 or the Saphir-23 in the Flogger. However that radar wasn't completely successful (perhaps it would have been better if they actually copied this time). The wings were much larger and had a different aspect.
The J-8II's resemblence to the MiG-23 is trivial---copying only the variable intakes and the folding ventral fin in the back. The radar on the J-8II is much larger than on the MiG-23. The J-8II is practically a new fighter despite the name---it shares only 30% of the components with the J-8I. The J-8II is actually the first Chinese fighter to use composites, little at first as it may be.
The J-8 only vague resembles the MiG-21 in layout. Structurally, the plane is quite different. Two engines, round intake with nose splitter, and the radar design was totally indigenous as it didn't really resemble any Russian radar at all, not the one used in the MiG-21 or the Saphir-23 in the Flogger. However that radar wasn't completely successful (perhaps it would have been better if they actually copied this time). The wings were much larger and had a different aspect.
The J-8II's resemblence to the MiG-23 is trivial---copying only the variable intakes and the folding ventral fin in the back. The radar on the J-8II is much larger than on the MiG-23. The J-8II is practically a new fighter despite the name---it shares only 30% of the components with the J-8I. The J-8II is actually the first Chinese fighter to use composites, little at first as it may be.
J-8 resablenes to MiG-21 came from the fact that the chinese choosed to use the later as a base to their own fighter which was mented for different task than the orginal model. This was due the fact that chinese lacked the design and engineering skills to developt a totaly indegenious design. Thus they adopted a "beef-up" style of remodelling the MiG-21 which they already manufactured. The seccond engine came from the operational requirements, but despite the twin engine arragment, the overall airframe design was very close to the orginal MiG-21, only in larger scale. The orginal manufactor of the MiG-21 in Soviet Union made similar type of "two-engined" Fishbed under the name Ye-152. This plane however wasen't exactly same as the chinese one, but featured very similar airframe.
J-8II is continiuos development from the J-8 and has nothing to do with MiG-23, like Crobato said. J-8II is similar remodelling form the first J-8 variant in a way as the Q-5 is from J-6/MiG-19. Both remodellings featured a side-intakes which in J-8II design allowed bigger radar to be fitted. Tough J-8 and J-8II may only 30 % of the components, the design of the J-8II itself is directly derivated form the J-8 and the variations are just natural progress of all continious developments.
J-8II is continiuos development from the J-8 and has nothing to do with MiG-23, like Crobato said. J-8II is similar remodelling form the first J-8 variant in a way as the Q-5 is from J-6/MiG-19. Both remodellings featured a side-intakes which in J-8II design allowed bigger radar to be fitted. Tough J-8 and J-8II may only 30 % of the components, the design of the J-8II itself is directly derivated form the J-8 and the variations are just natural progress of all continious developments.
That's not really correct. External appearances mean nothing when your fundamental guts are so different. Designing an airframe around a single engine is radically different from designing an airframe around two engines. This is especially so since the MiG-21 is a monoque, so essentially the plane is designed around the engine and the airframe is literally the skin.
You can't do that with a twin engine. You need a core frame or platform to support the two engines. And then you have to design two ducts each toward the engine. If you look at the J-8I head on, you will see in middle of the mouth is a huge splitter that splits the airflow into two tunnels. That's very different from the MiG-21. And when you have the two tunnels, you have to design the airframe around these two tunnels instead of one.
From the structural perspective, the J-8I resembles a lot more of the MiG-19/J-6 which is also a twin engine and uses a splitter feeding two air tunnels. In a way it's actually a fusion between the MiG-19 and MiG-21, but calling it a MiG-21 derivative don't make sense from a structural engineering viewpoint.
You can't do that with a twin engine. You need a core frame or platform to support the two engines. And then you have to design two ducts each toward the engine. If you look at the J-8I head on, you will see in middle of the mouth is a huge splitter that splits the airflow into two tunnels. That's very different from the MiG-21. And when you have the two tunnels, you have to design the airframe around these two tunnels instead of one.
From the structural perspective, the J-8I resembles a lot more of the MiG-19/J-6 which is also a twin engine and uses a splitter feeding two air tunnels. In a way it's actually a fusion between the MiG-19 and MiG-21, but calling it a MiG-21 derivative don't make sense from a structural engineering viewpoint.
Well I didn't call it a derivate, just that it had much design features taken from the MiG-21. What you said about the fitting the twin engine is true and neccecerical to fit two engines to airframe of this kind. The fact that it resambles MiG-19 in away is rather logical as it was the only twinengined jetfighter the chinese where familiar of. So what J-8 is, is a chinese developted fighter which used as much as possiple of design features of the planes already been manufactured in the country. Some might say it's rude and obsolent plane, but to me all these "poor-mans" solutions have always been fasinating.
Indeed it is a very fascinating plane. By the way if you look at straight into the J-8I's nozzle and see the splitter inside, and you see a J-6's intake and see the splitter inside, the similarity is apparent. Since you have twin ducts to the engine, the aircraft's cross section would be more of an oval.
One major difference between the YE-152 and the J-8I is that the former failed to embody the "Coke bottle" principle as used in planes like the F-102 Delta Dagger. This design enables a plane to break through the sound barrier faster and smoother, using less power. The designers of the J-8I appeared to already know this principle, which were already being incorporated among many American jet fighters over Vietnam. Hence the YE-152 is a lot more fat waisted while the J-8I is thin waisted.
Nonetheless the J-8I had a history of flight problems, one of which is some instability at high mach. It must have been smoothed out at some point or anotehr. The plane seems remarkably well built, as apparently all the J-8I and its variants are still in service today, making them some of the oldest planes in the PLAAF. Consider how much shorter the careers of the J-7C/D were in comparison.
One major difference between the YE-152 and the J-8I is that the former failed to embody the "Coke bottle" principle as used in planes like the F-102 Delta Dagger. This design enables a plane to break through the sound barrier faster and smoother, using less power. The designers of the J-8I appeared to already know this principle, which were already being incorporated among many American jet fighters over Vietnam. Hence the YE-152 is a lot more fat waisted while the J-8I is thin waisted.
Nonetheless the J-8I had a history of flight problems, one of which is some instability at high mach. It must have been smoothed out at some point or anotehr. The plane seems remarkably well built, as apparently all the J-8I and its variants are still in service today, making them some of the oldest planes in the PLAAF. Consider how much shorter the careers of the J-7C/D were in comparison.
Here is another odd aspect between the J-8I vs. the MiG-21. Even though they have a similar aerodynamic configuration, their flight behavior seems poles apart. The MiG-21 is a lot more agile plane while the J-8I and all J-8IIs for that matter are never known to be the most maneuverable of aircraft. They simply prefer to fly fast and straight.
I think this has something to do with the aforementioned factors.
The ratio of the fuselage length to the wingspan.
The sweep of the wings (the angle of the forward delta).
The aspect ratio of the wings (length from forward wing root to the rear wing root in relation to wingspan).
The distribution of weight in the aircraft.
I'm not sure where the obsession for length comes from. The J-8I is extremely long for a fighter (looks even longer than the YE-152). If you got an aircraft whose fuselage length is very long in relation to wingspan, you're going to have yaw problems (tail swinging sideways) when you roll. That's going to be nasty indeed for the pilot. The F-100 Super Sabre, the F-104 Starfighter, the F-101 Voodoo and the F-105 Thunderchief all had these problems one way or another. I guess the plane has an enormous tail stabilizer plus the lower stabilizers under the engine to help counter this.
I think one reason why the J-8I looks so thin and long compared to the YE-152 is because the Chinese engineers are minimizing cross section, hence less drag and more speed. So the mass is distributed over length. I bet the cockpit will be long thin and cramped too, like a long bathtub.
The wing fences are small for wings of its size. While the MiG-21 suffers from high wing loading which required long runaway takeoffs, the J-8 seems to have a lot of wing and appears to take off quickly. The plane does appear to have low wing loading. But given the sharp degree of the forward edge of the delta, which seems even more aggressive than the MiG-21's, this appears to be a lot of sacrifice in low speed handling just for high speed performance. Adding a wing fence helps remedy the flow of air over the wing rather than have the air flow bleed outward the edge. It took them a long long time to finally and partly remedy this by adding a second wing fence in the J-8H.
I think this has something to do with the aforementioned factors.
The ratio of the fuselage length to the wingspan.
The sweep of the wings (the angle of the forward delta).
The aspect ratio of the wings (length from forward wing root to the rear wing root in relation to wingspan).
The distribution of weight in the aircraft.
I'm not sure where the obsession for length comes from. The J-8I is extremely long for a fighter (looks even longer than the YE-152). If you got an aircraft whose fuselage length is very long in relation to wingspan, you're going to have yaw problems (tail swinging sideways) when you roll. That's going to be nasty indeed for the pilot. The F-100 Super Sabre, the F-104 Starfighter, the F-101 Voodoo and the F-105 Thunderchief all had these problems one way or another. I guess the plane has an enormous tail stabilizer plus the lower stabilizers under the engine to help counter this.
I think one reason why the J-8I looks so thin and long compared to the YE-152 is because the Chinese engineers are minimizing cross section, hence less drag and more speed. So the mass is distributed over length. I bet the cockpit will be long thin and cramped too, like a long bathtub.
The wing fences are small for wings of its size. While the MiG-21 suffers from high wing loading which required long runaway takeoffs, the J-8 seems to have a lot of wing and appears to take off quickly. The plane does appear to have low wing loading. But given the sharp degree of the forward edge of the delta, which seems even more aggressive than the MiG-21's, this appears to be a lot of sacrifice in low speed handling just for high speed performance. Adding a wing fence helps remedy the flow of air over the wing rather than have the air flow bleed outward the edge. It took them a long long time to finally and partly remedy this by adding a second wing fence in the J-8H.