Most helicopters do not have escape devices. How to ensure pilot safety in the event of an accident?

In people’s minds, armed helicopters are majestic “air horses” and “tank killers”. But in fact, helicopter pilots are one of the most dangerous jobs in the world. Helicopters fly at low altitudes and at slow speeds, and their battlefield survivability is relatively weak. In the face of unexpected accidents, the survival rate of pilots is ten times lower than that of fixed-wing pilots. one part.

So when a helicopter is hit or encounters irreversible mechanical failure, how do pilots survive in the line of fire?

The flight principle of a helicopter mainly relies on the rotor on the top of the aircraft and the tail rotor on the tail to provide lift and control the direction. It is precisely because of the existence of the top rotor that once an accident occurs, the helicopter cannot eject directly like a fixed-wing fighter. Instead, the rotor and cockpit glass must be blown up first, and then the pilot ejects out of the cabin.

Due to the special nature of helicopters, the helicopter's unique autorotation and forced landing method is usually used, or the idea of ????enhancing self-protection is adopted to ensure the safety of the pilot and crew. At present, there are three main ways for helicopters to rescue themselves in distress. Namely: spin forced landing, anti-fall design, and ejection rescue.

The first type of auto-rotation forced landing (with limitations)

Compared with fixed-wing aircraft flying at an altitude of thousands of meters, those who are used to flying at "the height of a tree" The helicopter flies at a low altitude, leaving the pilot with a short reaction time. However, a Chinese expert told the Global Times on the 27th that after a problem occurs with the helicopter's power system, there is a unique autorotation method for forced landing, which can reduce the impact of the forced landing to a certain extent.

However, forced landing due to rotation is subject to many objective conditions. First of all, it has high requirements on the pilot's technical and psychological quality. The entire handling process requires the pilot's precise judgment and decisive operation. Secondly, not all situations are suitable for autorotation and forced landing. When the helicopter makes an emergency landing, it does not descend vertically, but has a certain forward speed.

If the emergency landing site is located in a mountainous area, even if the descent speed is controlled, a collision may still occur.

The second type of fuselage is designed with crash resistance

Helicopters, especially military helicopters, take crash resistance into consideration when designing in order to improve survivability and protect the safety of crew members. As an important indicator, special measures have been taken for the cockpit, seats, landing gear, fuselage and mailbox. Once the helicopter crashes to the ground, most of the impact energy will be absorbed or converted through partial structural deformation and damage, and the impact on the pilot and the pilot will be minimized. Crew member impact.

For example, some helicopters use honeycomb sandwich materials under the body to absorb part of the energy by using its deformation after falling to the ground; while other helicopters have skid-type landing gear or hydraulic actuator-type landing gear that can Absorbs 60% of the energy of falling to the ground.

For example, the American AH-64 "Apache" armed helicopter pays special attention to impact-resistant design. The body can withstand a crash impact of 20G without injuring the people on board. The pilot's seat has also been specially shock-absorbed. The design ensures that the pilot will not be seriously injured when landing due to earth impact. The fuel tank can also withstand the impact of a crash and will be automatically closed to prevent an explosion.

Another example is the American "Black Hawk" series of helicopters. The landing gear uses a combination of shock absorbers and anti-fall energy-absorbing casings. The shock absorbers can withstand a vertical sinking speed of up to 11.9 meters/second. Within this speed range, all impact kinetic energy is absorbed by the buffer device. In addition, the crash sensor and breakable connector of the "Black Hawk" helicopter can immediately cut off the electrical system, prevent leakage of fuel lines, and self-seal the fuel tank in the event of a crash to ensure that there will be no fire due to oil leakage after the crash.

Data show that these designs enable the "Black Hawk" helicopter to achieve a 95% survival probability for the crew when it touches the ground at a vertical speed of 12.8 meters/second. The "Apache" attack helicopter also achieves this level. One standard. In Black Hawk helicopter accidents, the probability of crew survival averages 85%.

The third ejection life-saving technology (currently only in Russia)

Ejection life-saving measures are the most active and ideal life-saving measures. The ejection life-saving system mainly consists of the ejection control system, landing system and personal life-saving kit. Among the helicopters currently in service in the world, only Russia dares to be the first in the world. Its Ka-50 "Black Shark" and Ka-52 "Alligator" helicopters adopt the K-37 rocket ejection life-saving system, which includes ejection Rockets, seats, parachutes, etc.

The bottom of the seat is also equipped with life-saving equipment such as a life raft, medical bag and a radio signal.

When the pilot performs an ejection operation, the explosive bolts between the rotors will blow off all the rotors and the canopy glass will also be blown off. Subsequently, the ejection rocket above the seat was ignited, pulling the pilot out of the cabin to a height of about 40 meters. The parachute opens automatically during the descent. After that, the pilot will land on the ground at a speed of less than 7 meters/second to complete the escape.

However, the helicopter's active escape device has many hidden dangers in terms of operability and safety. On the one hand, helicopters have a torque problem, that is, the fuselage rotates with the rotor and relies on the tail rotor to maintain balance. However, after a helicopter crash, the fuselage is often unable to maintain balance, making it difficult to meet the angle requirements for ejection. On the other hand, when a helicopter ejects, it must first blow up the rotor, a process that is inherently dangerous.

It is undeniable that equipping helicopters with ejection escape systems is a general trend. With the advancement of microelectronics technology, material technology, and mechanical manufacturing technology, future helicopters will be equipped with ejection life-saving systems with artificial intelligence.

However, for military helicopters with complex combat environments and harsh operating conditions, it is far from enough to rely solely on the pilot's self-rescue ability. Therefore, the world's major helicopter development powers are also developing other helicopter crew life-saving technologies and life-saving equipment.

Helicopter integrated rescue cabin technology. In this rescue solution, the helicopter's crew compartment, which is also the rescue capsule, is a modular component of the helicopter. When a helicopter malfunctions during flight, in order to save the life of the helicopter pilot, the helicopter's rotor, engine and excess fuselage can be cut off first, so that the rescue capsule can be separated from the crashed helicopter as a whole. Then, the rescue capsule released its parachute and slowly landed in a safe place.

Rocket towing life-saving technology. This technology has similar principles to the rocket ejection seat life-saving technology, but it is also different from the rocket ejection seat life-saving technology. When the rocket ejection seat life-saving technology is used to escape, the helicopter crew is restrained on the seat and separated from the out-of-control helicopter together with the seat; while when the rocket towing life-saving technology is used to escape, only the helicopter crew is pulled away from the helicopter alone by the rocket. Before rocket towed life-saving technology was put into use, the only way for helicopter pilots and crew to leave an out-of-control helicopter was artificial parachuting. That is, the crew must first put on the parachute system, then open the hatch, and then jump out.

Life-saving techniques after helicopter emergency landing on water. When a helicopter engine fails or is damaged by enemy fire during a mission, the helicopter must make an emergency landing immediately. When helicopters of the US, Russian, British, French and other countries perform missions at sea, they are usually equipped with a flotation system under the fuselage. This type of system usually consists of multiple flotation bladders plus a stabilizing device. When the helicopter makes an emergency landing on the water, the float bags will inflate automatically or in accordance with the pilot's instructions. After the buoyancy bag is inflated, the helicopter can float on the water surface without sinking. In this technology, there is no gap between China and other countries.

Perhaps, in the near future, with the advancement of microelectronics technology, material technology, and mechanical manufacturing technology, it will be possible to equip future helicopters with ejection life-saving systems equipped with artificial intelligence.

But before that, protecting the safety of pilots and preventing helicopter accidents ultimately depends on our precise and meticulous ground maintenance and rigorous and conscientious flight operations.