What's the use of these long cable-stayed wire ropes on airplanes?

In the first ten years of its invention, the aircraft was basically made of wood as keel material and canvas skin. In order to increase the lift, most of them adopt two or even three wing structure. Therefore, it is necessary to arrange the cable-stayed wire rope with triangle layout between the upper and lower wings, between the airframe and the wings to strengthen the strength of the whole aircraft. Later, steel was used as the main keel, and aluminum alloy was used as the secondary support structure and skin of the aircraft. It is no longer necessary to pull a large number of steel wires between the wing and the fuselage of the aircraft to strengthen the structural strength.

However, the vertical tail, tail, flap and other aerodynamic surfaces of the aircraft still need to use steel wire combined with pulley, spring and other pneumatic control. But these wires can no longer be seen from their appearance. Today, on yun8, hong6 and other airplanes, from the cockpit ceiling of the nose to the front of the tall vertical tail, if you carefully observe, you will still see a long and thin cable-stayed "rope". Obviously, it's also a wire rope. Is it still necessary to pull a steel wire to increase the structural strength of the huge vertical tail for such a large aircraft?

Or is it necessary to use this wire rope to transmit the pilot's control force and deflect the tail rudder on the vertical tail? In fact, these two guesses are not right! Modern medium and large transporters and bombers have enough structural strength, so it is not necessary to pull the steel wire obliquely between the body and the large wing surface to increase the overall strength. In modern medium and large-scale aircraft, all the aerodynamic airfoils have been hydraulically assisted or even electrically operated.

All the hydraulic structures are hidden inside the airframe and wings, and no external steel wire is needed to transmit the control force. The speed of the aircraft is often hundreds of kilometers or even thousands of kilometers per hour. These cable-stayed steel wires are not likely to be used for drying clothes. The visible cable is actually an antenna of an airborne radio station. Its scientific name is cable antenna, also known as cable antenna, or cable type high-frequency antenna. The tension wire antenna is a kind of rigid wire antenna, which is widely used in propeller aircraft before and after World War II; the first generation of jet fighters; and modern low-speed large aircraft. The main purpose is telecommunication.

The utility model has the advantages of simple structure, high efficiency and low cost. The wavelength suitable for airborne radio station is between 3 meters and 30 meters. There are wire antennas on the backs of planes like Yun 7, Yun 8 and Hong 6. Early Soviet made MiG-15, J-5 and j-jiao-5 aircraft also had such antennas. But then it was basically cancelled on fighter planes. The main types of tensioned wire antennas are T-type and tilt type. Tilt type is the most widely used one. This kind of antenna is easy to maintain in all kinds of situations. But the disadvantages of this kind of antenna are also obvious, according to LKS.

First, the additional aerodynamic resistance is relatively large. If the flight speed reaches high subsonic speed of 900 km / h, in order to overcome the extra aerodynamic resistance of such a "long rope" outside the airframe, it needs to pay hundreds of horsepower for the extra output power of the engine and increase the fuel consumption significantly. In addition, in the working frequency band, the input impedance of the antenna changes in a large range, which makes the matching work more difficult; in addition, there is a risk of icing on the rope of the tensioned antenna. As a result, almost all contemporary supersonic aircraft are no longer equipped with this kind of cable pulling antenna. Instead, they are replaced by short blade antenna with high structural strength and low air resistance.

Some people think that this kind of cable antenna represents backward technology, but it is not. Although the modern airborne satellite communication and data link have been very mature, the medium and short wave airborne radio is still a very common backup. In fact, the C130 series aircraft and even the E2 series early warning aircraft in the United States still have this kind of antenna. It's not just on airplanes. In the past few years, there has been a conventional submarine suddenly floating on the important channel. It can be seen that the "steel wire rope" that commands the enclosure and the front and back of the hull is actually covered with kelp. In fact, this is also the tension wire antenna for submarine surface communication.