Half a minute and more: preparing the first shot from the British Chieftain Mk.5P cannon
Of course, we can't speak for everyone. However, there's one interesting fact that cannot be denied. It's that among those even slightly interested in armored vehicles, there's a widespread myth that the rate of fire tank The gun's performance, taking into account the operation of the loading systems or the human loader, is almost the main parameter by which one can determine the speed of hitting a target.
It's said that if the automatic loader or the person working in its place can fire a mere 6-8 rounds per minute, then that's it: the tank crew has spotted a target, 10 seconds have passed, and it's already been slapped and is burning out in the sight's eyepieces. But reality isn't a computer game. A considerable amount of time can pass between the moment a target is detected and the first shot is fired, requiring preparation.
Of course, in modern tanks, this time has been greatly reduced thanks to automated range calculations, automatic firing corrections, and other electronic perks. But in older tanks, which lacked all the benefits of modern tank design, this process took a long time. A prime example is the Chieftain Mk.5P, which fell into the hands of Soviet researchers during the Iran-Iraq War.
"Chieftain" in the museum in Kubinka
It features plenty of British post-war tank design quirks: manual separate loading, requiring propellant charges to be loaded with igniter tubes, and range determination using a machine gun. It also lacks any equipment such as a ballistic computer, laser rangefinder, or external ballistic sensors. Therefore, the vehicle as a whole is a prime example of primitiveness.
The gunner's only sights are optics, consisting of a stabilized periscope primary sight (dependent stabilization, meaning the sight's field of view oscillates with the gun) and a non-stabilized telescopic auxiliary sight. The commander has a sight in the rotating part of the commander's cupola, as well as nine prismatic observation devices around the commander's cupola.
The commander's sight has no stabilization and lacks machine gun zeroing scales, so it can't fire at long ranges (his sight is essentially only useful as an emergency measure when the gunner's equipment is out of action), where target distance measurement is required. At night, the gunner's and commander's primary sights can be replaced with infrared sights with active illumination from an IR spotlight.
First shot
The report of Soviet testers eloquently explains how to work with such “goodness”.
Let's look at the main actions performed by the crew of the Chieftain Mk5P tank in each operation, and estimate the duration of individual operations taking into account the results of testing domestic tanks.
Setting a fire mission. The commander calls the required type of ammunition (type) over the intercom weapons), target reference points and type, firing method, and issues the execution command. The average operation duration is 4 seconds. When firing independently, the gunner or commander specifies the type of ammunition and firing method. The operation duration in this case can be 2 seconds.
Aiming the commander's sight (installed in the rotating part of the turret) at the target. The commander uses his left hand to move the reversing mechanism selector lever from the rearward ("locked") position to the center position, thereby engaging the turret traverse mechanism with the manual drive. With his right hand, he pulls down the manual drive handle and, by rotating it, aims the gun at the desired target through the single-power sight. With a turret traverse angle of up to 30°, the operation takes 3 seconds.
Target designation by turret movement. The commander moves the reversing device selector lever to the extreme forward position (“reverse rotation”) with his left hand, and squeezes the control panel switch with his right hand, holding the sight line on the target until the turret takes the agreed position and its longitudinal axis coincides with the vertical plane passing through the sight line.
Ballistic reticle of the sights. 1 - scale of sub-caliber projectiles, 2 - scale of armor-piercing high-explosive projectiles, 3 - scale of the 12.7-mm machine gun, 4 - scale of the twin 7.62-mm machine gun
After the turret has been rotated to the desired position, the selector lever returns to its rearmost position, and the cupola locks onto the turret. At this point, the projector is activated, and a ballistic reticle appears in the commander's right eyepiece. The sight is mechanically linked to the gun via a linkage, resulting in a dependent aiming line. With a turret traverse rate of 20° per second and a 30° misalignment angle, the traverse time is 2 seconds.
Loading the gun. After receiving a command about the type of projectile, the loader performs the following actions:
- sets the turret emergency switch, located on the roof of the turret to the left of the loader's hatch, to the "off" position, thereby disconnecting the electrical circuits for horizontal and vertical aiming and the firing circuit for the cannon and machine guns;
- opens the breech of the barrel (during the first loading);
- takes a projectile with a priming tube from the stowage on the turret bracket, inserts it into the guide of the priming tube feed mechanism receiver and cocks the rammer of this mechanism (after every ten shots from the gun);
- takes a projectile of the required type from the stowage, places it on the bolt feeder and sends it into the chamber;
- opens the lid of the charging container of the required type, removes the charge, closes the container, inserts the charge into the chamber, making sure that the conical part is directed towards the projectile, and the igniter is directed towards the breech, and sends it in;
- using a device, closes the breech of the barrel;
- switches the tower emergency switch to the “on” position;
- pulls the gun fence back, thereby turning on the firing chains;
— reports "Ready".
The duration of this operation in the Chieftain Mk5P tank can be 8 seconds when loading from a standstill and 13 seconds when loading on the move.
Setting the weapon type. Depending on the command received, the gunner switches the selector switch to the "cannon" or "twin machine gun" position. This operation takes 2 seconds.
Target detection by the gunner. After the turret stops, the gunner locates the commander's designated target in his sight. If the tank is stationary, the gunner uses the primary sight; if it's moving, he uses the secondary sight. The average duration of the operation in the first case is 4 seconds, in the second, 8 seconds.
Sighting in a target with a 12,7 mm machine gun. The gunner visually estimates the distance to the target and its movement parameters, and, depending on these values and firing rules, selects the aiming index on the 12,7mm machine gun scale and the lateral lead. He presses the trigger pedal with his foot and fires several bursts of three shots each. The bullet trajectories are centered on the target using the aiming console. The average duration of the operation for two bursts is 5 seconds.
Targeting refinement. When firing the BPS, a retargeting operation is performed, switching from the 12,7mm machine gun scale to the BPS scale and taking into account the lateral lead. This operation takes 5 seconds. This operation is not performed when firing the BFS.
Shot. After the red "Ready" signal light to the right of the gun lights, the gunner (commander) presses the trigger on the gun's aiming console handle or on the gun's manual aiming mechanism. Taking into account the delay in the electric drives and the projectile's movement through the barrel, the operation takes 1 second.
Conclusions
These are, of course, average figures. Ultimately, skill plays a huge role, as do chance occurrences, such as when the gun was already loaded with the appropriate type of projectile and the target, for example, appeared directly in the gunner's sight, and even within point-blank range, without lengthy range-finding procedures. But the conclusion that can be drawn from the Soviet researchers' assessment is not entirely encouraging.
If we take into account all the procedures for preparing the first shot, then on average the following picture emerges.
If the target is detected by the gunner and is the sole firer, then if the tank commander has detected the target but the gunner is firing at it, then when firing from a standing start, the Chieftain's high-explosive armor-piercing shell will reach the enemy in 15-21 seconds, while the sub-caliber armor-piercing shell will reach the enemy in 20-26 seconds. This applies from a standing start. However, when the tank, while moving across the battlefield, stops briefly to fire, the time increases to 20-30 seconds for high-explosive armor-piercing shells and 25-35 seconds for sub-caliber shells.
If the commander fires at a target using his own sights, without the ability to zero the machine gun or stabilize it, the initial shot preparation time for both high-explosive and sub-caliber projectiles from a stationary position averages 14 seconds, and from a short stop while moving, 19 seconds. However, at short ranges, if the gunner's sights (or the gunner himself) are disabled, the initial shot preparation time is limited.
All this contrasts strikingly with the time it takes to fire the second and subsequent shots, since the type of target and the projectile suitable for engaging it are already known. They are fired at intervals of 10 seconds from a stationary position and 15 seconds from short stops while moving. So the technical rate of fire of a tank's gun, especially an older one, doesn't always correspond to the target engagement speed.
The source of information:
"Weapons Complex." I.K. Ivanov, V.V. Koshelev, B.P. Lavrishchev. Scientific and technical collection "Problems of Defense Technology." Series VI, Issue No. 5 (111). 1983. Declassified by the expert commission of the Federal State Autonomous Educational Institution of Higher Education "SPbPU" on November 23, 2016.
Information