What is the stall spin mentioned repeatedly in "King of the Sky"? How to deal with it?

In the movie "Lord of the Skies", the test pilot devoted himself to researching and repeatedly testing an anti-spin parachute, which played a role in correcting the aircraft's spin during the test flight.

Pictured: The scene of the test aircraft stalling and spinning after hitting a bird in the movie "King of the Sky" (Source: Movie screenshot)

A tailspin is a special state that occurs when an aircraft stalls during flight. When the aircraft's angle of attack exceeds the critical angle of attack, the lift coefficient will decrease sharply as the angle of attack increases, and the lift will decrease and the drag will increase sharply. After the aircraft stalls, if the stall of the two wings is not coordinated, the lift coefficients of the left and right wings are inconsistent, and the lift difference generated by the left and right wings will intensify the aircraft's roll toward the side of the completely stalled wing, causing the wing to rotate, and the nose of the aircraft will deflect toward the lower side of the wing, and the direction will continue to tilt due to the roll. In this state, the vertical component of the lift is less than the weight of the aircraft, and the aircraft will quickly drop in altitude. The horizontal component of the lift forms a centripetal force, so the aircraft descends in altitude while performing a small radius circular motion. This state is a tailspin.

A tailspin is a very dangerous flight state. If the aircraft is operated in the normal way, it will not only fail to correct the tailspin, but will aggravate the aircraft's lateral roll, seriously endangering flight safety. Since the performance and characteristics of the test aircraft are often not fully understood, the test pilot may enter a tailspin when testing the aircraft's marginal performance and performing large-volume maneuvers.

Understanding the principle of an aircraft entering a spin will help you build confidence in getting out of a spin. A spin is caused by the wing's rotation after the aircraft stalls. Stall and rotation are the key to entering a spin, so the key to getting out of a spin is to "stop rotation" and "get out of a stall." In the 1970s, the Chinese Air Force faced the problem of entering a spin many times during air combat training. After theoretical research and repeated test flights, they independently explored a set of control methods for getting out of a spin, which can be summarized as "flat, neutral, and smooth." "Flat" means immediately releasing the rudder after discovering that the aircraft has entered a spin; "neutral" means setting the control stick to neutral; and "smooth" means, after determining the direction of the aircraft's rotation, pressing the stick in the direction of the aircraft's rotation, stopping the aircraft from rolling, and pushing the stick past neutral to get out of a stall and exit the dive state. This control method has been popularized in aviation units, significantly improving flight safety.

For a new aircraft that is still in the test flight stage, the characteristics of the tailspin are not yet fully understood. In order to reduce the risk of tailspins and ensure the safety of test pilots and test equipment, a simpler, more direct and effective way to recover from a tailspin is to install an anti-spin parachute at the tail of the aircraft. After entering a tailspin, the test pilot only needs to press the parachute release button, and the parachute canopy will generate aerodynamic force to stop the aircraft from rolling and make the aircraft pitch down. Therefore, the role of the anti-spin parachute is also to "stop rolling" and "recover from stall." After recovering from the tailspin, the parachute is thrown away.

Pictured: The anti-spin parachute on the X-29 aircraft (Source: Weibo)

It should be emphasized that installing an anti-spin parachute on an aircraft will increase drag and weight. Therefore, the anti-spin parachute is only used on test aircraft to ensure flight safety. For combat aircraft, pilots are still required to be proficient in flight principles and have the skills and confidence to recover from spins.

Wang Mingzhi, a military expert, joined the Air Force in June 1980, received a master's degree in military science in 1991, and a doctorate in military science in 2000. He was a professor at the Air Force Command College and held the rank of professional technical colonel.

Produced by: Science Popularization China

Producer: Guangming Online Science Department

Author: Wang Mingzhi (military science writer)

Scientific review: Fei Boyu (senior military content editor)

Planning: Jin He