What kind of aircraft is the F-22 fighter?

According to the plan of the US Air Force, the F-22 fighter group has formed initial combat effectiveness from June 5438 to February 2005, and the US Tactical Air Force will officially enter the fourth generation fighter era. The world's first fourth-generation fighter has been widely reported, but the significance of its advanced technology in flight and even actual combat is mostly vague. To this end, this print specially invites Mr. Fang Fang, a famous aviation writer, to write this article to reveal the true performance of the F-22 after the data fog. As the first and only fourth-generation supersonic fighter in the world, F-22 has become the de facto epoch-making standard of the fourth-generation supersonic fighter with its "supersonic cruise, super maneuverability, stealth and maintainability" (so-called S4 concept, and some data also include "short takeoff and landing", which is called S5). There are many books on the F-22, but there are few about the characteristics and flight tests of aircraft. Fortunately, CODEONE magazine interviewed the F-22 test pilot. This paper attempts to obtain information from interviews and analyze the advantages of F-22 in combat from the perspective of flight performance at both ends of the most prominent flight envelope, especially the comparison with Su -37, which is also known for its super maneuverability. Supersonic Performance Supersonic Cruise Capability 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". In fact, supersonic cruise capability 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. On the first point, the author has read the article mentioned the "supersonic cruise capability" of MIG -25/3 1 more than once. In fact, these two kinds of aircraft have only achieved supersonic flight for a long time on the basis of extremely large oil load in the aircraft. For the second point, it is often ignored, and it is considered that as long as the flight number exceeds 1 without afterburning, it can be called supersonic cruise. The British mentioned in an article introducing their own lightning interceptor that its afterburner M number reached 1.0l, so it was the first aircraft in the world to realize supersonic cruise. With the development of engine technology, some third-generation fighters have been able to fly in transonic/hypersonic region without external stores (MO.9-M 1.3, 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 fourth generation supersonic fighters, if the third generation or even the first/second generation supersonic fighters can easily achieve supersonic cruise, then this standard 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 and the supersonic lift-drag ratio is improved. Combined with the engine with large thrust and low fuel consumption, the supersonic performance of the aircraft has achieved a staged leap. The tip of the iceberg of this superior performance is supersonic cruise, which is its significance and one of the reasons why it can become one of the first generation standards. If we only focus on the quantitative standards without considering the essence behind them, I am afraid it is biased. Imagine that if F- 15 can be fitted with F- 1 19 engine, then the number of m may reach M 1.2 or even higher without afterburning, but its supersonic performance is definitely not as good as that of F-22, because its aerodynamic design is still underwater for 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 flying your Raptor to intercept an intruder, the supersonic cruise capability will greatly increase your average speed of approaching the enemy, extrapolate the interception line, and attack the opponent before he enters the weapon range. Cruise speed as high as M 1.5 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 M0.9 to M 1.5 (assuming the carrier advantage is higher here), the power range of AIM- 120 Amram is also increased by 50%. AIM- 120 launched from an F-22 flying at M 1.5 has a much faster initial speed and can use more fuel in the subsequent voyage, so it can hit the target at a distance of 50% farther than the original distance. If the overflight capability is combined with the stealth capability of the F-22, the AN/APG-77 radar with passive positioning capability and the AN/ALR-94 electronic warfare system, it can be said that the F-22 has the advantage of "finding the enemy first, firing first and shooting down first" that pilots dream of in over-the-horizon air combat. Ok, now suppose your AIM- 120 has entered the homing stage, or your raptor is unfortunately locked by the other side (of course, if this happens, you will probably need to go back to Nellis base to make up lessons), then what you need to do is to get rid of the effective attack specifications of the other side's missiles. 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 supersonic cruise capability combined with supersonic maneuverability can keep your raptor in a high energy state during defensive maneuvers, thus greatly reducing the shooting distance of opponents and the effective attack range of missiles. In this case, your chances of survival are much higher than that of a plane maneuvering at subsonic speed. Author: 2 19. 149.46. Reply to this statement-. In the comparative flight test with F- 15/F- 16, if the F-22 doesn't want to entangle with them and speed up the separation, then the Eagle and Falcon can't catch up with the Raptor with supersonic cruise capability in any case-although these excellent third-generation fighters all adopt semi-oil configuration to improve their flight performance as much as possible, the result is still the same: Raptor can make The F-100-11129/229 F- 16 will not lag far behind the Raptor in breaking the sound barrier in initial acceleration. However, when the Raptor enters the high Mach number supersonic cruise state, the game is actually over. No plane can match the supersonic endurance of a raptor. F- 16 and F- 15, which are being pursued, can't catch up with the Raptor in either the acceleration stage or the continuous cruise stage after adding the typical combat load. In this regard, Paul Mays, the chief test pilot of the F-22, recalled, "Our test flight mission is always limited by the amount of fuel to catch up with the aircraft. A simple "bingo" will force us to slow down and then take the pursuer to the tanker to refuel. At this point, the raptor's fuel tank is still full. If this next-generation fighter does not show obvious advantages in front of today's planes, I will become a firm anti-taxpayer. Raptors are excellent in many aspects, and a raptor cruising at supersonic speed is quite outstanding. " In addition to air combat, if the F-22 needs to cross the opponent's air defense system, the supersonic cruise capability can also improve its survivability. The reason is the same as above: the shorter the time to cross the detection range of air defense system sensors, the shorter the response time 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 forward interception, high speed obviously shortens the effective shooting time, because the missile must chase a high-speed target, and the relative angular velocity is too large, which consumes energy when turning sharply. Behind the supersonic cruise capability, the acceleration/climb performance conceals the fact that the engine thrust of the Raptor is large and the drag is small. After considering the aircraft load factor, its residual power per unit weight (its absolute value is equal to the climb rate of the aircraft in the same state-author's note) is quite amazing. Engine is one of the important factors. F119-pw-100 maximum thrust is 97.9 kN, afterburner thrust 155 kN. It has high reliability, can withstand the drastic change of throttle, and is the ideal power of fighter. The design of fixed inclined plate inlet emphasizes the requirement of supersonic cruise, which has higher efficiency and less resistance at the designed cruise speed, and the acceleration performance and Ps at the right end of flight envelope are obviously improved. For the F-22, the factor limiting its maximum speed is not engine thrust, but other factors including fuselage strength, especially at low altitude. In order to prevent the pilot from exceeding the maximum speed limit due to no operation, the F-22 is equipped with a maximum speed prompt and warning system to remind the pilot when the aircraft approaches the maximum speed limit. The characteristics of low drag mainly benefit from two aspects: excellent aerodynamic design (especially considering the need of supersonic cruise, but the total drag is the lowest near the engine speed M 1.5 and at an altitude of 40,000 feet) and the design of the built-in bomb bay. You can compare F- 15. F- 15 claims that the sprint speed can reach M2.5, but that is in the case of net shape. After hanging the bomb, due to the increase of anti-jamming ability, the maximum M number of the aircraft is only M 1.78, and the acceleration decreases seriously when it approaches M 1.7. The performance of the F-22 is much better here. According to the test pilot, "it is very easy to accelerate at all altitudes with military thrust or less, but if you use full afterburner, the acceleration is simply shocking." I wish I could explain it in figures, but they are still confidential. Using military thrust, when approaching the speed of sound, the acceleration decreases with the increase of resistance, but it is still easy to break through the sound barrier. Raptor flies transonic with military thrust, which feels like F- 15 afterburner. When the full force is applied, the acceleration of the raptor becomes stable and strong. Between M0.97 and M 1.08, the aircraft has slight buffeting. After that, until the maximum speed, the acceleration of the raptor remains stable and continuous. During the test flight, we like to enter the supersonic cruise state as soon as possible to make full use of our narrow supersonic airspace. We put the afterburner into supersonic cruise and retract the throttle when the test conditions are reached. Now many high-speed test flights have been transferred to the Pacific Missile Range (between vandenberg air force base and Mugujiao Naval Air Station). We have a longer straight flight space here, which can minimize the impact of sonic boom on local residents. "In terms of climbing ability, the F-22 is also quite good. Traditional fighters use the Rudski climb curve when climbing rapidly. They climbed to the tropopause (about 36,000 feet) at subsonic speed, and then accelerated to supersonic climb. For raptors, these complex curves can be omitted and accelerated directly from the runway, becoming a supersonic climb. " This guy seems to be born for high-speed flight. "Paul mace commented. Author: 2 19. 149.46. Reply to this statement-. Supersonic hovering ability and supersonic maneuverability are one of the design focuses of the F-22, and also one of the "generation difference" signs between this aircraft and the third generation fighter. In addition to the above supersonic cruise 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 M 1.7. Considering that the hovering ability of /F- 15 is far from this under the same conditions, but Su -27 has reached this level only at M0.9 and in the air, it cannot be said that this is a quite amazing progress. Engine is an important reason to realize such a large supersonic hovering overload, as well as the supersonic lift-drag ratio and trim ability of the aircraft. The lift-drag ratio is not difficult to understand. In order to pull out enough overload, the wing must produce corresponding lift, and at the same time, the induced drag increases sharply (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 high, the induced drag will increase very quickly, which 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. Phantom -III has good instantaneous hovering performance and poor stable hovering performance, which is an example. In terms of modern aviation technology, it is not unusual to design a wing with high lift-drag ratio or a wing with good supersonic performance. This is also a point that the F-22 can be proud of. Balance ability is often easily overlooked. The large 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 moment, the aircraft will either enter the pitching divergence state out of control, or be pushed back by the bow moment generated by the wing lift, and the required angle of attack can't be pulled. Especially at any supersonic speed, the center of gravity of the aircraft moves backward greatly, and the bow moment generated by wing lift is quite humanized, so supersonic maneuvering needs stronger balance ability. MiG -25, which is famous for its supersonic performance, can't carry out supersonic maneuvers with large overload because of its flatness-the horizontal tail deflection of the plane is close to the limit when flying horizontally at supersonic speed, and the margin of supersonic maneuvers is quite small, so although the fuselage can bear more people's loads, the maximum hovering overload in M2 is only 3G. To solve the balancing problem, firstly, the static stability is greatly relaxed and the center of gravity of the aircraft is moved forward. In this way, although the center of gravity of the aircraft will still move backwards when flying at supersonic speed, the bow moment generated near the center of gravity is relatively small. But in this way, the plane 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 Israeli lion fighter has been unable to solve the problem of high angle of attack trim. Therefore, although there were a variety of duck layout schemes in the demonstration of ATF scheme (old aviation fans should remember the imagination of YF-22 duck layout in the 1980s), the F-22 finally chose the normal layout with strong balance ability, and the longitudinal static stability was relaxed to 15%. Another way to solve the balancing problem is to adopt the thrust vector control (TVC) technology. Using TVC, its main advantages are: on the basis of pneumatic control surface, balance means are added, and the balance ability is naturally greatly enhanced; When flying at high speed, the deflection of the pneumatic rudder surface will produce great human resistance, and TVC can achieve the same control effect without deflecting the rudder surface. TVC not only deflects the thrust vector, but also produces the normal component. The powerful engine jet will have an ejection effect on the rear fuselage, generating a new "lift" increment and participating in the trim. The supersonic maneuverability of the F-22 has been greatly improved, and TVC technology has contributed. Considering the characteristics of supersonic hovering, its greatest advantage is reflected in the increasingly important over-the-horizon air combat. As mentioned above, supersonic cruise capability is very useful in both offensive and defensive situations in over-the-horizon air combat, and supersonic hover capability is the key link to ensure the smooth connection between offensive and defensive conversion. When AIM- 120 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 into the dangerous melee too quickly. As you can imagine, for an aircraft like 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- 120 and reduce its effective range. Or in order to increase the effective range to supersonic speed, slow down 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 phase to cope with various emergencies. Post-stall maneuverability Generally speaking, the super maneuverability in s4 mainly refers to post-stall maneuverability. In order to have post-stall maneuverability, good flying quality and effective control means are two necessary foundations. Let's take a look at the performance of the F-22 at a high angle of attack, which may help us understand the advantages of this aircraft. Buffeting buffeting is a common flight feature of aircraft at angle of attack. Buffeting is a good hint for pilots. Buffeting is a direct manifestation of airflow separation at the rear of the upper surface of the wing, which is equivalent to informing pilots that the wing is close to the critical angle of attack and will stall soon. When the airflow separation advances to the leading edge of the aircraft, the aircraft will stall completely. For traditional aircraft, wing stall may cause the aircraft to enter a spin or other complicated flight state that is difficult to control. In addition, strong buffeting may not only damage the aircraft structure, but also seriously affect the use of weapon systems. Even a well-designed third-generation fighter needs careful control by the pilot at this time-if you don't want the plane to enter an unexpected ultra-high angle of attack, you need to check the rudder input immediately and reduce the angle of attack as soon as possible. Joan Bisray, who participated in the flight test of the F-22 left envelope, said: "The Raptor began to buffet around the angle of attack of 20 degrees until the buffet amplitude increased slightly at 26 degrees. The buffeting intensity of the Raptor is about the same as the minimum buffeting intensity of F- 16 at high angle of attack, but the maneuverability is far less than that of F- 15. From 26 degrees to 40 degrees, the buffeting intensity is basically stable, and it begins to decrease after exceeding 40 degrees. " According to the report of the F- 16/MATV flight test team, "Unless in the high subsonic state, the standard F- 16 will not have significant buffeting in the flight envelope limited by the normal angle of attack. Somewhere after exceeding the limit, we met the obvious and meaningful Tik Tok. Moderate buffeting occurred near the angle of attack of about 40 degrees, which lasted until 50 degrees, and then the amplitude weakened to almost disappear. " Compared with the classic third-generation fighter, the buffeting amplitude of F-22 is obviously reduced, which is due to its good aerodynamic design, which is very beneficial to the use of weapons (especially aircraft guns) at high angles of attack. In addition, there is a subtext in the report: the plane flies stably at high angle of attack, and there will be no sudden stall of the wing and then out of control. (To be continued) Fangfang F-22, the first and only fourth-generation supersonic fighter in the world, has become the de facto epoch-making standard of the fourth-generation supersonic fighter because of its "supersonic cruise, super maneuverability, stealth and maintainability" (the so-called S4 concept, and some data also include "short takeoff and landing", which is called S5).