The "black box" that is often sought in air crashes turns out not to be black!

The "black box" that is often sought in air crashes turns out not to be black!

The Cormal was the first commercial jet airliner developed by De Havilland Airways of the United Kingdom. On July 27, 1949, the Cormal 1 made its maiden flight. This jet aircraft has a pressure-resistant fuselage and four high-power turbojet engines known as "devil". It is not only powerful, but also very beautiful in overall shape. The spacious cabin and large windows make people feel unprecedentedly comfortable. Both insiders and outsiders have great expectations for its successful launch into the market.

"Cormer 1"

However, what happened next was unexpected. Just one year after its maiden flight, the Cormal had problems. Three planes broke in mid-flight. The tragic crashes shocked the world and the media. Subsequent analysis of the accident found that the fuselage breakage was caused by "metal fatigue". Obviously, metal fatigue was caused by abnormal strong vibrations during the flight. But what exactly caused this vibration? What happened when the accident happened? People have no way of knowing. The continuous accidents brought de Havilland into a catastrophic disaster, and it was forced to announce that the Cormal was temporarily withdrawn from the market.

The series of accidents involving the Cormier sparked an idea for David Warren, an Australian engineer at the Melbourne Aeronautical Research Laboratory. In 1934, when Warren was 9 years old, his father died in a plane crash. The series of crashes involving the world's first commercial jetliner had a profound impact on him, and he wanted to invent an instrument that could record the voices of pilots and abnormal sounds from various parts of the aircraft, so that future generations could analyze the accident and minimize or avoid similar accidents. After repeated experiments, he developed a drum-type device that used magnetic signals to record sound and data.

On March 1, 1953, Varennes demonstrated the instrument, but the invention was not well received. At the time, it was understandable that the magnetic recorder was unpopular. Unlike ordinary recorders, it had to work continuously during the flight of the aircraft, and it had to convert the sound from various parts of the aircraft into magnetic signals and record them. No matter where it was placed on the aircraft, it had to be connected to the various parts and mechanisms of the aircraft with cables, which would affect the overall structure and line installation of the aircraft. For this small machine, the aircraft had to undergo major surgery, which was something the aircraft manufacturer was extremely reluctant to accept. Australian Airlines rejected the invention on the grounds of "possible privacy disclosure", but the British, who had suffered a lot, accepted it and provided Varennes with a research fund.

A photo of Varun with the magnetic recorder he invented in 2010 when he was 85 years old

Varen's invention soon proved itself useful. In 1978, it helped to explain the cause of the first U.S. military air crash; in 1987, it helped to explain the international dispute over the explosion of a Soviet reconnaissance plane over Norway in the Barents Sea; and in 1960, after an accident that could not be explained, Australia finally accepted the device.

The device invented by Varenne is also called "black box". In fact, its scientific name is "flight recorder", abbreviated as FDR. There are two black boxes installed on general aircraft, one is specially used to record the sound of the cockpit and is placed under the pilot's seat; the other is placed at the tail of the aircraft and is specially used to record flight data. The mechanical devices and electronic devices of various parts of the aircraft are connected to it through sensors. With the development of electronic technology, the black box has been improved from the original magnetic signal recording to electronic signal recording, and the recording equipment has also been changed from the original mechanical drum type to the solid-state storage chip stack type, which has reduced the size of the recorder, reduced the daily maintenance work, increased the anti-seismic performance, and increased the storage capacity of information.

Device invented by Varenne

The black box in the cockpit can record the speech of the pilot, captain or flight attendant, and any abnormal sound in the cockpit, including threats and explosions, can also be recorded truthfully. The black box at the tail of the plane can store more data, including flight speed, acceleration, altitude, longitude and latitude, aircraft heading, flight trajectory, flight attitude, take-off and landing status, external temperature, cabin temperature, Greenwich Mean Time, fuel storage, cabin internal and external pressure, engine working status, etc. More than 100 data. It can be said that no matter what stage the aircraft is in, such as take-off, climbing, cruising, descending, approaching, landing, etc., it cannot escape the "ears" of the black box.

The third generation of "black box" Source: Baidu Encyclopedia

The color of the black box is not necessarily black. In order to be easy to identify, its appearance is often painted orange. In order to ensure that the black box can function safely after an accident, it must be resistant to shock, pressure, impact, heat, freezing, magnetism, interference, and immersion in seawater or kerosene.

In addition, the black box must also have its own battery. Once an accident occurs, it can not only record relevant information 30 minutes before the accident, but also automatically send out signals for 30 days to summon rescue personnel. The frequency of the ultrasonic call signal sent by the black box is 37.5 kHz, which is the special frequency specified for black boxes internationally.

Source: 365 Days in the History of Science, slightly edited

Author: Wei Fengwen and Wu Yi

Editor: Zhang Runxin