Chapter 245: The End of France (15)

"Descend to a height of one thousand meters."

The air commander's order immediately aroused strong dissatisfaction from other pilots. You know, for a bomber, a thousand meters is already quite dangerous. It is no exaggeration to say that it is equivalent to having one foot in hell.

But the air commander was also forced to do so. Before departure, the superiors issued a death order that they must crash into the German pontoon bridge. But in this pitch-black night, they couldn't see the target even if they wanted to crash. They could only lower the altitude to find the target before dropping the bomb.

Although they were full of complaints, the pilots had to obey the order to descend the flight altitude. After all, no one wanted to bear the crime of escaping in battle, which was a serious crime that would be shot in wartime.

Suddenly, a lamp post suddenly rose from the ground, and the dazzling light that tore through the darkness rushed to the sky.

Then came the second, third, and fourth...

When the light is weak, the pupil will automatically adjust and enlarge, allowing more light to enter, so that the eyes can see more clearly. The sudden strong light made the pilots who had been flying in the dark for a long time unable to adjust their eyes, and they were almost blinded. There was a white mist in front of them and they could not see anything clearly.

"Damn it! It's a searchlight, disperse immediately!" The air commander warned loudly. He knew very well that once he was covered by these lights, fierce artillery fire would follow.

As soon as the voice fell, the anti-aircraft positions on the ground began to fire fiercely.

Although more advanced fire control radars have not yet been put into use, the existing air defense radars can still accurately mark the direction and altitude of enemy aircraft, helping anti-aircraft artillery units to calibrate various design parameters in advance.

The most effective way for anti-aircraft guns to perform air defense combat missions is to form a dense barrage, making it impossible for the invading enemy aircraft to avoid it.

How to increase the density of the barrage? Before the appearance of proximity fuses, there were only two ways. The first was to increase the firing rate of anti-aircraft guns; the second was to increase the number of anti-aircraft guns when setting up air defense positions.

Because of this, every time the anti-aircraft artillery units carried out air defense operations, the ammunition consumption was always a terrifying number.

During World War II, there were several types of fuzes used in anti-aircraft shells, namely trigger fuzes, time fuzes/height fuzes and proximity fuzes.

Trigger fuzes are generally used for small-caliber anti-aircraft guns. Because shells with trigger fuzes must hit aerial targets to work, but it is very difficult or impossible to hit small targets that are moving quickly at high altitudes, so this type of trigger fuze is only used for small-caliber anti-aircraft guns against low-altitude targets.

The time fuze is a dial similar to a mechanical clock inside the shell, which is powered by the elastic potential energy of the spring. There is a circle of scales outside the fuze, which represents the length of the delay. Before firing, the gun crew needs to observe and measure the altitude of the enemy aircraft group, and then calculate the corresponding delay time. Before firing, a special wrench is needed to adjust the fuze to the corresponding scale. When the fired shell flies for a preset time, it will explode and cause damage to nearby targets.

The principle of the height fuze is similar to that of the time fuze. The detonation height of the shell is set before firing. Anti-aircraft shells equipped with these two types of fuzes are mostly fired by larger caliber anti-aircraft guns.

If these settings are wrong, even if the aiming is accurate, it will not work because it will detonate too early or too late. Because the chance of hitting is small, anti-aircraft guns must fire a considerable number of shells using these two types of fuzes to create a barrage where the target may pass, which will increase the probability of shooting down the target.

For example, during the Battle of Britain in World War II, the British air defense forces used 4,200 large and medium caliber anti-aircraft shells to shoot down a German plane. The cost of these anti-aircraft guns and the air defense shells consumed was probably several times the cost of shooting down the plane. When the US military's 127mm dual-purpose anti-aircraft guns use shells equipped with time or height fuzes, they need to fire 2,000 rounds to shoot down an enemy plane.

Later, proximity fuzes appeared. This type of fuze does not require complex calculations. It only needs to fire the shells equipped with this type of fuze in the direction of the target. When the shell approaches the target, or the distance between the shell and the target is lower than the set limit in the fuze, the shell will automatically detonate, which greatly improves the efficiency of the anti-aircraft gun. A 127mm dual-purpose anti-aircraft gun that needs to fire 2,000 rounds to shoot down an enemy plane only needs 500 rounds on average when using a proximity fuze to shoot down an enemy plane.

This radio proximity fuze is a prototype developed by the United Kingdom based on the principle of radar. Later, it was improved by the United States and the Mk53 fuze was developed, which is mainly used on 127mm anti-aircraft guns. After the shell equipped with a proximity fuze is fired, the safety device is released, the fuze starts to be powered, and the vacuum tube is made into a radio frequency circuit to emit 180-220MHZ electromagnetic waves.

When approaching an aerial target, the electromagnetic wave will be reflected back, and due to the Doppler effect, a frequency shift of hundreds of hertz will be generated. At this time, the shell shell itself constitutes an antenna to receive the reflected electromagnetic wave, and it is filtered and amplified through a filter and amplifier. When the amplified current reaches the threshold (indicating that the distance to the target is within the effective killing range), the detonation can be completed.

However, this fuze was limited by the level of electronic devices at the time. At that time, the US military could only install it on 127mm anti-aircraft guns, and could not use it on smaller caliber Bofors 40mm anti-aircraft guns and 28mm anti-aircraft guns.

In fact, Germany also studied proximity fuzes during World War II, but because of the poor electronic technology, it failed to develop radio proximity fuzes. Instead, it developed a mess of things such as sound proximity fuzes, magnetic induction proximity fuzes, electrostatic proximity fuzes, etc., which were not very effective.

Among them, the principle and structure of the electrostatic proximity fuze are very simple. It only needs two dry batteries, a spark discharger, an electric igniter, and an insulated electrode of the fuze shell. The electromotive force of the battery is selected to be slightly smaller than the release voltage of the spark discharger, and no current passes through the electric igniter before approaching the target.

When the shell approaches the target, a potential difference is generated between the electrode and the fuze shell, and it is fed back to the circuit. Due to the existence of the potential difference, the voltage added to the spark discharger lead will increase, and increase proportionally with the approach of the target until a certain distance is reached. The high-intensity electrostatic load released by the target makes the total voltage of the spark discharger reach a sufficient value for electrical spark discharge, and finally triggers the electric igniter to ignite the explosive in the warhead.

The principle of static electricity in objects that can be found everywhere, and an ordinary static electricity receiving circuit can create a highly lethal static electricity proximity fuze. For objects like aircraft that can generate thousands of static electricity loads at any time due to notification, the static electricity proximity fuze is just what it should be used for.

However, it has a disadvantage that the sensing distance is too short, far inferior to the radio proximity fuze, and its practicality is too poor; but even such a useless thing is regarded as a treasure by the German high-ranking officials, and such fuzes will never be installed on non-top precision anti-aircraft ammunition.