The V-22 "Osprey" is a tiltrotor that combines the advantages of a first-class and fixed-wing aircraft, allowing it to take off, land and hover in a variety of environments, as well as maneuver at high speeds. It's an innovative design, but it's also a high-risk one. Its development has gone through more than 20 years of arduous development, costed a huge amount of money, and the unit price of the whole machine is as high as $70 million. It had a number of fatal accidents during its test flights, which resulted in the deaths of more than 30 people. Even after mass production, its accident rate has remained high, with at least 70 publicly reported flight accidents. On January 29, 2017, a U.S. Marine Corps V-22 crashed during a raid mission in Yemen, killing one person and injuring three. Was this an accidental accident or an inevitable consequence? Let's break it down.
The V-22 had frequent accidents, mainly because its body design was too complex, there were some aerodynamic defects, and it was not very adaptable to the environment. Its biggest challenge was the vortex state of the airflow encountered during landings and low-speed dives, a phenomenon that is common to gyroplanes, but more serious for the V-22. The vortex state of the turbulence refers to the formation of a clockwise rotating annular air flow around the rotor due to the induced velocity of the rotor and the opposite direction of the relative airflow when the rotorcraft descends at low speed. This airflow can reduce the lift of the rotors, causing the aircraft to descend faster, lose control, or even fall to the ground in reverse. The V-22 is easier to get into the airflow vortex ring and harder to get out of due to its special design such as highly inclined propeller blades, rigid propeller material, overweight fuselage, and double brackets that are prone to instability. In order to avoid this from happening, the US military stipulated that the V-22 should not descend at a speed of more than 40 meters per second when it landed vertically, but this speed was too slow, making the V-22 a live target for the enemy. It's a dilemma.
In addition to the vortex state of the airflow, the V-22 also faced the problem of downwash airflow. Downwash airflow refers to the downward movement of the airflow through the wing caused by the lift force generated by the wing. The V-22's rotors rotate very fast and produce strong downwash airflow, which can have a great impact on the vision of the pilot and crew, as well as cause hazards to personnel and equipment on the ground. The V-22 once fell into the water because the pilot could not see the water due to the downwash airflow, and also threw two Marines off the plane because of the downwash airflow. The downwash can also affect the V-22's ability to carry out rescue missions, as it reduces visibility on the surface of the water and can also cause water in the belly of the aircraft, causing danger.
The V-22 had many other problems, such as the fact that it did not have a nose** and personnel lift, which would have reduced its fire support and rescue capabilities. It also had flaws in its hydraulic line design, which, if hit by a shell, could cause the aircraft to lose hydraulic power and subsequently lose control. There are also contradictions in its flight manuals and test reports, such as the question of whether it can land safely without the rotor taking advantage of the power to rotate. In conclusion, the V-22 is a controversial piece of equipment that has advanced performance, but it also has a lot of problems. One Marine who participated in the test put it well: "I don't think the V-22 is suitable for combat. ”