J-20 into the supersonic invincible

Fighter 20 into the supersonic invincible

Zhu and the 90th anniversary of the military after the parade, the F -20 pilot a "supersonic invincible" triggered a wide range of outside attention.

The world is not broken Wu Gong fast, supersonic cruise allows fighters can quickly enter, withdraw from the battlefield, giving the aircraft a strong battlefield flexibility. Sonics cruise has become the fifth generation fighter standard, but there is an exception, that is, F-35. Interestingly, the F-35's thrust is the largest of the existing fighter engines. Ultrasonic cruise, of course, depends on many factors, but the F-35 so much of the thrust can not be supersonic cruise? Today, the Northern Defense (ID: sinorusdef) special writer Flak to talk about this matter.

In the case of

The F-35's engine has the biggest thrust in active fighters

Supersonic cruise is not enough engine thrust can only, only on the engine itself, the problem must first know that the engine is better than the "anti-supersonic cruise", which is why the Boeing 777 engine thrust so big did not take you Moon. The turbofan engine's outer channel not only does not contribute to the supersonic thrust, but also increases the supersonic resistance, so the more you can not reach the Sonics, the more you can. The force of the combustion chamber is "absolutely anti-supersonic cruise", and there is no matter for you.

In the case of

△ F-35 F-135 engine is being tested

So, what is the supersonic cruise? Or in the case of the same engine diameter, magnify the core segment? Especially to enlarge the channel ratio to 0, that is, pure turbojet engine, not you can cruise cruise? The answer can be said to be right or wrong, because some aircraft do with pure vortex jet supersonic cruise, such as the Russian Navy using the P-700 "granite" anti-ship missiles, or Concorde aircraft Oliver 593 engine is indeed Can cruise cruise.

In the case of

△ "Peter the Great" cruiser launched P-700 "granite" heavy-duty anti-ship missiles, the use of turbulence power to the full supersonic speed of 500 km range

That pure vortex spray of the three generations of machines do not a bunch of cruise can be supersonic? Of course not, the answer lies in the thrust of the engine than the three generations of turbojet engine thrust in the 5 up and down, which means that you zoom in at the same time, the engine's weight loss is also increased, so you either sacrifice the load, or sacrifice the whole aircraft Pushing the weight ratio, the results of thrust is not enough to cruise cruise. Three generations of countries have chosen the latter to the three generations of the ancestor of the F-4 "ghost" as an example, it is to use a large load to open the trend. So that the aircraft to reduce the load, into a speed only, no voyage without armed manned "missile" is unthinkable.

As for the four generations of machines is said in front of its engine to join the channel than to push the weight ratio increased to 8, but the channel than it is "anti-supersonic cruise." So the five generations of machines to supersonic cruise, the engine will reduce the bypass ratio (magnification core section) at the same time, to maintain or even increase the weight ratio. The problem is again, the so-called external channel is pure air without weight of this paragraph, and the core section is filled with high-pressure compressors, combustion chamber and high pressure turbine and a pile of metal, you have to metal core section Enlargement does not increase the weight, it is impossible.

In the case of

The second stage of the SU-57 engine will be further optimized for supersonic cruise performance

Therefore, to meet the supersonic cruise target, the only way is to reduce the length of the core segment, when the compressor series less, the weight naturally reduced, make up the weight of the compressor blade elongated, which is Three generations of the era of material science and heat flow process can not do things.

It is reported that the fifth generation of the Soviet fighter Su-5-stage engine "30" is the cold end (low pressure compressor) from the AL-41F1 four-level compression with a turbines reduced to three-level compression and a Turbo, engine hot end (high pressure compressor) from the AL-41F1 nine-level compression with a turbo compacted into a five-stage compression with a turbo, the string outside the sound should be the hot end of the compressor with the combustion chamber to zoom in, so the total weight difference Not the case to reduce the channel than in order to achieve the four generations of the engine can not be supersonic cruise targets.

In the case of

△ F -20 whether it is AL-31FM1 or "Taihang" engine thrust are 13-14 tons, F-35 engine thrust than the J-20 thrust more than the F-7 engine is also high

Another reference is that the F-35's F-135 engine thrust, although from 16 tons to more than 19 tons, but the channel ratio from 0.2 zoom nearly twice and become 0.57, as the F-35 can not supersonic cruise one of the reasons.