What is the fifth generation fighter in the United States?

there is no fifth generation, only the fourth generation in the United States, such as the F-22F-35

when it comes to supersonic performance, the first thing to mention is supersonic cruise capability. The concept of supersonic cruise is no stranger to aviation enthusiasts. However, due to the inaccuracy of many media reports, this concept is often confused with concepts such as "supersonic flight".

supersonic cruise capability actually refers to the ability of an aircraft to cruise at a higher supersonic speed without afterburner. In this concept, two points must be made clear: 1) no afterburner; 2) Higher supersonic speed. As for the first point, the author has read more than once that the article mentioned the "supersonic cruise capability" of MIG -25/31. In fact, these two types of aircraft are only using afterburner to realize supersonic flight for a long time on the basis of extremely large fuel load in the aircraft. For the second point, it is often ignored, and it is considered that as long as the flight M number exceeds 1 without afterburner, it can be called supersonic cruise. In an article introducing their own "Lightning" interceptor, the British mentioned that the aircraft's M number reached 1.1 without afterburning, so it was the first aircraft in the world to achieve supersonic cruise. With the development of engine technology, some third-generation fighters have been able to fly in the transonic/hypersonic region without external stores and afterburner (M.9~M1.3, generally only slightly more than 1, not close to the upper limit). These planes can't be regarded as achieving supersonic cruise.

as one of the criteria for dividing the 4th generation supersonic fighter, if supersonic cruise can be easily realized by the 3rd generation, or even the 1st/2nd generation supersonic fighter, then this criterion can be thrown into the garbage. The above two points are only quantitative standards, not the essence of supersonic cruise-through advanced aerodynamic design, the supersonic zero-lift drag coefficient is greatly reduced, the supersonic lift-drag ratio is improved, and the supersonic performance of the aircraft is staged by combining with the large thrust and low fuel consumption engine. The tip of the iceberg of this superior performance is supersonic cruise, which is its significance and the reason why it can become one of the generation standards. If we only focus on the quantitative standard without considering the essence behind it, I am afraid it will be biased. Imagine that if the F-15 can be fitted with the F119 engine, the number of M may reach M1.2 or higher without afterburning, but its supersonic performance is absolutely inferior to that of the F-22, because its aerodynamic design is still the level of the third generation fighter.

so what tactical advantages can supersonic cruise bring to the F-22? As far as this capability itself is concerned, its advantages are generally reflected in interception and over-the-horizon air combat.

if you are in an attack situation, or you are driving your raptor to intercept an intruder, the supersonic cruise capability will greatly improve your average speed of approaching the enemy, extrapolate the interception line, and attack the opponent before he enters the weapon range. The cruising speed above M1.5 will give you the advantage of "the enemy fires first, and the enemy shoots down first". For example, when the carrier speed is increased from M.9 to M1.5 (assuming that the carrier has a high advantage here), the power range of AIM-12 Amram also increases by 5%. AIM-12 launched from an F-22 flying at M1.5 has a much faster initial speed, and more fuel can be used in the subsequent voyage, so it can hit the target at a distance of 5% farther than the original distance. If the overflight capability is combined with the stealth capability of the F-22, the AN/APG-77 radar and the AN/ALR-94 electronic warfare system with passive positioning capability, it can be said that the F-22 has the advantage that pilots dream of "finding the enemy first, firing first and shooting down first" in over-the-horizon air combat.

ok, now suppose your AIM-12 has entered the homing phase, or your raptor is unfortunately locked by the other side (of course, if this happens, you will probably need to go back to Nelis to make up lessons), then all you need to do is to get out of the effective attack range of the other missile. As long as you don't go up against the missile, then any maneuver you make will lead to the narrowing of the attack range of the other missile-in fact, the difference between the total energy of the missile at the moment of launch and the total energy of the raptor determines the size of this range. The ultra-patrol ability combined with supersonic maneuverability can keep your raptor in a high energy state during defensive maneuvers, thus greatly reducing the firing distance of the opponent and the effective attack range of the missile. In this case, your chances of survival are much higher than that of an airplane maneuvering at subsonic speed.

In addition to air combat, if the F-22 needs to pass through the opponent's air defense system, the patrol capability can also improve its survivability. The reason is the same as the above: the shorter the time to cross the detection range of air defense system sensors, the shorter the reaction events left for air defense system. The higher the cruising speed of the raptor, the more difficult it is to intercept, and the more significant the reduction of the attack range of the air defense system. Whether it is tail chase or front interception, high speed significantly shortens the effective firing time, because the missile must chase a high-speed target, and the relative angular velocity is too large, so it has to consume energy in sharp turns < P > Behind the supersonic cruise capability, there is a fact that the engine thrust of the Raptor is large and the resistance is small. After considering the weight of the aircraft, its residual power per unit weight (Ps, its absolute value is equal to the climb rate of the aircraft in the same state) is quite amazing.

the engine is one of the important factors. F119-PW-1 has a maximum thrust of 97.9KN and afterburner thrust of 155KN, which is highly reliable and can tolerate the drastic change of throttle, and is an ideal power for fighter. The design of the inlet with fixed inclined plate focuses on the requirement of over-patrol, which has higher efficiency and less resistance at the designed cruising speed, and the acceleration performance and Ps at the right end of the flight envelope are obviously improved. For the F-22, the factor limiting its maximum speed is not the engine thrust, but other factors including the strength of the fuselage, especially at low altitude. In order to prevent the pilot from exceeding the maximum speed limit due to no operation, the F-22 has installed a maximum speed prompt and warning system to remind the pilot when the aircraft is close to the maximum speed limit.

the characteristics of low drag mainly benefit from two aspects: excellent aerodynamic design (especially considering the need of over-patrol, the total drag is minimum near the design speed of M1.5 and at the height of 4, feet) and the design of built-in bomb bay.

you can compare the F-15. F-15 claims that the sprint speed can reach M2.5, but that is under the condition of net shape. After hanging the bomb, due to the increase of interference resistance, the maximum m number of the aircraft is only M1.78, and the acceleration is seriously reduced when it approaches M1.7. The performance of the F-22 in this respect is much better. According to the test pilot: "At all altitudes, horizontal acceleration with military thrust or less is very easy, but if full afterburner is used, its acceleration is simply shocking. I wish I could explain it in figures, but they are still confidential. When using military thrust, the acceleration decreases with the increase of resistance when approaching the speed of sound, but it is still easy to break through the sound barrier. Raptor flies transonic with military thrust, which feels similar to F-15 afterburner. When the full afterburner is turned on, the acceleration of the raptor becomes stable and strong. Between M.97~M1.8, the aircraft has slight buffeting. After that, until the maximum speed, the acceleration of the raptor kept steady and continuous. During the test flight, we like to enter the super-patrol state as soon as possible to make the best use of our narrow supersonic airspace. We put the afterburner into the super patrol, and when the test conditions are met, we take back the throttle. Now many high-speed test flights have been transferred to the Pacific missile range (between Vandenburg Air Force Base and Point Mugu Naval Air Station). We have a longer straight flight space here and can minimize the impact of sonic booms on local residents. "

in terms of climbing ability, the F-22 is also quite good. The traditional fighter plane uses Rutsky climbing curve when climbing quickly. They climbed to the tropopause (about 36, feet) at subsonic speed, and then accelerated to supersonic speed to climb. For the raptor, these complicated curves can be omitted, and the acceleration can be pulled directly from the runway and turned into supersonic climbing. "This guy is like being born for high-speed flight." Paul Mays commented like this.

supersonic hovering ability

supersonic maneuverability is one of the design focuses of the F-22, and it is also one of the "generation difference" signs between this aircraft and the third generation fighter. In addition to the above-mentioned super patrol and supersonic acceleration/climb performance, the hovering ability in supersonic state has also been significantly improved. According to some data, the aircraft's stable hovering overload can reach 6.5G at M1.7. Considering that the F-15' s hovering ability is far worse than this under the same conditions, while the Su -27 only reached this level at M.9 and in the air, it cannot be said that this is a quite amazing progress.

the engine is an important reason for achieving such a large supersonic hovering overload, and equally important are the supersonic lift-drag ratio and trim ability of the aircraft.

it is not difficult to understand the lift-drag ratio. In order to pull out enough overload, the wing must produce corresponding lift, which is accompanied by a sharp increase in induced drag (the induced drag coefficient is proportional to the square of the wing angle of attack and inversely proportional to the wing aspect ratio). If the induced drag coefficient is too large and the induced drag increases very fast, it will soon offset the residual thrust of the engine. Although the aircraft may still pull out a large overload, the engine thrust is not enough to maintain stable flight. The Phantom III of that year had good instantaneous hovering performance and poor stable hovering performance, which is precisely why. In terms of modern aviation technology, it is not particularly difficult to design a wing with high lift-drag ratio or a wing with good supersonic performance, but it is not a day's work to combine the two. This is also a point that the F-22 can be proud of.

however, the balancing ability is often overlooked. The high lift of the wing is the basis of pulling out large overload, but the greater the lift, the greater the pitching moment. If the aircraft itself can't provide enough pitching trim moment, it will either go into the pitching divergence state and get out of control, or it will be pushed back by the bow moment generated by the wing lift, and it can't reach the required angle of attack. Especially under supersonic conditions, the focus of the aircraft moves backward greatly, and the bow moment generated by wing lift is quite large, so it needs stronger balancing ability to carry out supersonic maneuvers. The MIG -25, which is famous for its supersonic performance, is unable to carry out supersonic maneuvers with large overload because of its plain-the horizontal tail deflection of the aircraft is close to the limit when it flies horizontally at supersonic speed, and the margin for supersonic maneuvers is quite small, so although the fuselage can bear a larger load, the maximum hovering overload at M2 is only 3G.

to solve the balancing problem, firstly, the static stability is greatly relaxed, and the aircraft focus is moved forward. In this way, although the focus of the aircraft will still move backward during supersonic flight, it is close to the center of gravity and produces relatively small bow moment. However, in this way, the aircraft will also face the problem of trim when maneuvering at subsonic high angle of attack-this time it is the head-up moment generated by trimming the wing. Harry hill Lake, the chief engineer of F-16, once said: "The best position of the duck wing is on someone else's plane." The well-known LAVI fighter has never been able to solve the problem of high angle of attack trim. Therefore, although there were many duck layout schemes in the demonstration of ATF scheme in that year (old aviation fans should still remember the imaginary map of "YF-22" with duck layout in the 198s), the F-22 finally chose the normal layout with strong balancing ability, and the longitudinal static stability was greatly relaxed. Another way to solve the trim problem is to adopt thrust vector control (TVC) technology. Using TVC, its main advantages are as follows: on the basis of pneumatic control surface, a balancing means is added, and the balancing ability is naturally greatly enhanced; When flying at high speed, the deflection of pneumatic control surface will produce great resistance, while TVC can achieve the same control effect without deflection of control surface; TVC doesn't just deflect the thrust vector to generate the normal component, but the powerful engine jet will form an ejection effect on the rear fuselage, generate a new "lift" increment, and participate in the trim. The supersonic maneuverability of the F-22 has been greatly improved, and TVC technology has contributed greatly < P > As far as the characteristics of supersonic hovering itself are concerned, its greatest advantage is reflected in the increasingly important over-the-horizon air combat. As mentioned earlier, in over-the-horizon air combat, the over-patrol ability is very useful in both attack and defense situations, and the supersonic hovering ability is the key link to ensure the smooth connection between attack and defense. When the AIM-12 enters the homing phase, the F-22 needs to turn to high-speed detachment in order to avoid entering the effective range of the opponent's weapon or rushing too fast into the risky close combat. It is conceivable that for aircraft such as F-15, in order to turn as soon as possible, the speed before turning needs to be kept near its corner speed, and then it is accelerated to leave after turning, which will inevitably limit its speed when launching AIM-12 and reduce its effective range; Or to increase the effective range to supersonic speed, slow down again after launch, but at the expense of time. For the F-22, there is no such trouble at all. Good supersonic hovering ability enables it to maintain a high energy state in the over-the-horizon combat stage to cope with various emergencies.