It's not easy for fighters to get on board ■ Wang Xiaomeng and Tong Yiwei On October 29, the U.S. Navy released the naval aviation vision 2030-2035, which revealed the operational concept design and details of the next generation shipborne aircraft - F / a-xx fighter attack aircraft. At the end of last year, France announced the development plan of new nuclear powered aircraft carriers and carrier based aircraft. NGF / SCAF carrier based aircraft, which is used to replace "gust", "Bumblebee" and other carrier based aircraft, is scheduled to make its first flight in 2025. Prior to this, the Indian Navy's "Guanghui" carrier aircraft completed the sliding jump take-off test on the aircraft carrier vikrand. All this makes people think that the curse of "it is difficult for fighters to get on board" has been broken, but in fact it is not. Even if they have been on board, the active carrier aircraft still need to face various problems. This is the reason why the United States is still upgrading the "super Hornet" carrier aircraft. So, what factors need to be considered for a fighter to get on board? How can we create a qualified shipborne fighter? See the interpretation. Su-33 shipborne fighter. "Gust" - M carrier aircraft. Data picture The use demand is traction To build a fighter suitable for use on an aircraft carrier, many factors need to be considered, such as the size of the aircraft carrier flight deck, hangar, elevator, etc. But the fundamental point depends on the Navy's positioning of the carrier aircraft. If the Navy chooses a light aircraft carrier, the two engine heavy carrier aircraft will not be on board. If the catapult technology is not mature enough, the aircraft carrier can only choose vertical / short takeoff and landing fighter or sliding jump takeoff / blocking landing carrier aircraft. In short, for the development of Shipborne aircraft, the use demand is traction. After the end of World War II, the United States has been taking the "road of large aircraft carrier", and its shipborne aircraft tend to be heavy-duty. For example, F-4, F-14 and other fighters belong to double engine heavy fighters. The F / A-18E / F fighter in service is also the product of large-scale design based on medium-sized aircraft. The takeoff weight of the f-35c fighter is 31.5 tons, while the takeoff weight of the U.S. F-15 heavy fighter is 30.8 tons. Therefore, the f-35c is actually a heavy fighter dressed in a medium-sized aircraft. For the same reason, the Soviet Navy also developed and equipped some heavy fighters. Since the 1970s, the Soviet Union has gradually shifted from building Kiev class medium-sized aircraft carriers to developing large aircraft carriers. Accordingly, the carrier based aircraft has changed from vertical takeoff and landing to sliding jump takeoff / blocking landing. In the selection of Jacques-141 vertical / short takeoff and landing fighter and mig-29k and su-27k conventional takeoff and landing fighter, the Soviet Union finally selected the su-27k heavy fighter, which was later named Su-33 shipborne fighter by Russia. In recent years, the strength of Russian aircraft carriers has changed, and the carrier based aircraft equipped by the Russian navy have been adjusted accordingly, mostly mig-29k medium fighters. Other countries are usually equipped with light aircraft carriers for various considerations. Therefore, some vertical / short takeoff and landing fighters have become the choice of many countries. Structural strength is fundamental Take off and land on the aircraft carrier - this specific environment determines that the designer must focus on the structural strength of the carrier based aircraft and adopt a variety of measures to strengthen some important parts. First, the landing gear. Different from the "flat floating" landing of land-based fighter, in order to land on the deck with limited length accurately, the carrier aircraft must land at a fixed sliding angle. In addition, the aircraft carrier has actions such as pitching, swinging and heave in the wind and waves. The vertical impact energy generated by fighter landing can sometimes reach 4 ~ 6 times the impact energy of land-based aircraft on the ground. Therefore, different from the landing gear of land-based fighter, the structural strength of the landing gear of carrier based aircraft must be high enough to ensure that it can withstand the impact force of carrier based aircraft when landing. The ejection fighter must also be equipped with a hook on the front landing gear, which has high strength requirements to ensure that it can withstand the afterforce during ejection and take-off. Taking Su-33 shipborne aircraft as an example, the aircraft is improved on the basis of Su-27 fighter, and the main load-bearing structure of the fuselage is strengthened, including changing the front landing gear into two wheels, the main landing gear is directly connected with the tail beam, and a new hydraulic buffer system is adopted. After a series of enhanced design, the Su-33 carrier based aircraft has a maximum takeoff weight of 26 tons and a maximum service overload of 8G, which can land safely under the condition of large longitudinal overload. The second is the arresting hook and supporting structure. Some shipborne aircraft must rely on the arresting system in order to change from a large landing horizontal speed to a stop state in a short distance. The specific process is as follows: the carrier aircraft landing on the ship uses the arresting hook to hang the arresting cable, the hydraulic buffer device in the arresting device starts to work, and finally "pulls" the carrier aircraft. Taking the American mk-73 arresting line buffer as an example, it can make the carrier based aircraft with a weight of more than 30 tons stop after sliding 91.5 meters after landing. Obviously, in this process, shipborne aircraft, especially the arresting hook, have to face huge arresting load. Therefore, the arresting hook and the supporting structure connected with it must be strengthened to not only withstand the impact of instantaneous large energy, but also not lead to the sharp increase of the weight of the carrier aircraft. This undoubtedly puts forward high requirements for designers. The third is folding wings. In order to save space and increase the number of carrier aircraft, the wings of carrier aircraft are often designed as foldable structures, which enables some medium-sized aircraft carriers to be equipped with heavy fighters. This design means that the wing must be folded and opened by the actuator, which will lead to insufficient strength of the wing separation surface. In addition, the folding wing has higher requirements for strength due to the influence of factors such as the oil volume of the wing tank, the loading capacity of the hanging point and the wind load on the deck. When France designed the gust-m carrier based fighter, it gave up folding wings because of the particularity of delta wings. In the design of Su-33 carrier based aircraft, not only the front wing is added, but also the integral flap and aileron is changed into a double slot flap and a separate aileron at the wing tip. A wing folding mechanism is designed between the double slot flaps to meet the strength requirements of the wing when taking off and landing on the aircraft carrier. Surging power is the foundation High thrust aeroengine is very important for carrier aircraft. Compared with land-based fighters, the engine requirements of Shipborne aircraft usually include greater thrust / power and better acceleration, while balancing the relationship between weight, fuel consumption, structure and size. Under the conditions of Shipborne use, the engine has more strict requirements for electromagnetic compatibility, oil and maintenance support resources, and the anti-corrosion performance in marine environment is also important. So many high requirements are superimposed in the development process of Shipborne aircraft engine, which makes its development more difficult and longer cycle. In this regard, it is also difficult for some countries with strong national strength to make many breakthroughs. Therefore, in the development of Shipborne aircraft, the general practice is to give priority to the engine with mature technology, or develop the engine that can meet the needs and characteristics of the Navy on the basis of the engine with mature technology. The French "gust" - M carrier aircraft initially used f404 engine, and later replaced the former by its domestic snicker M88 turbofan engine. However, in order to reduce the changes to the aircraft platform, the overall performance, overall dimension and installation interface of snike M88 turbofan engine are required to be the same as f404 engine. The next generation of Shipborne aircraft may adopt more advanced variable cycle adaptive engine. The engine not only has large thrust, but also can automatically change the engine operation mode according to different states such as cruise and air combat, so as to achieve the best fuel consumption. At present, some countries have built prototypes and are conducting comparative tests. However, there is still a long way to go when the variable cycle adaptive engine can be officially equipped with shipborne aircraft. System of systems operations is a "hard indicator" Carrier based aircraft is an important part of aircraft carrier battle group. This determines that the development of Shipborne aircraft cannot be carried out independently, but should be planned in the whole combat system. For example, the U.S. Navy has some "hard indicators" for the design requirements of F / a-xx: first, it should be able to integrate with the active shipborne aircraft wing and can be carried by the active aircraft carrier. Its take-off, landing and operation will not have a great impact on the hull structure and the operation of other shipborne equipment. Second, it can effectively support manned and unmanned carrier based aircraft operations, including command and control of unmanned carrier based aircraft, and has the capabilities of air oil receiving, tactical reconnaissance, target surveillance and interception, electronic suppression and precision strike. Third, it can perform long-term infiltration combat tasks in a specific combat environment to ensure air control. In the U.S. naval aviation vision 2030-2035, the F / a-xx fighter attack aircraft has become a three wing layout similar to the Su-33 carrier based aircraft, which is helpful for taking off and landing on the aircraft carrier and air combat maneuver. In addition, the latest design of F / a-xx also includes a sharp triangular main wing, dual engines, no vertical tail, etc., which is similar to the previous yf-23 stealth fighter project and has good stealth performance. This change is likely to make the F / a-xx have a longer range and faster speed than the active f / A-18E / F fighter attack aircraft of the U.S. military. Moreover, due to the integration of some passive and active sensors, it may play the role of on-the-spot command in the "UAV + UAV" system. On the other hand, vision is only vision after all. It still needs a longer time to verify when it can be successfully developed, when it can be assembled, when it can form combat power, and what reference it can bring to the development of a new generation of Shipborne aircraft all over the world. (photo: Yangming) (outlook new era)