B90 Fuze
Contents
B90 Fuze
B90 a mechanical clockwork time fuze for high-explosive fragmentation projectiles (HE). Projectiles with the B90 are best used against self-propelled and towed guns (mortars), lightly armored vehicles, exposed enemy personnel, and personnel in trenches without overhead cover.
Effective engagement occurs at a burst height of 10–20 m above the target. If the timing mechanism fails to function, or the fuze is set in error toward a longer time, the fuze will function on impact (PD).
The fuze arms at a distance of 50–300 m from the gun.
This fuze was developed back in the USSR, but some manufacturers adapted it to NATO standards by changing the seating thread. There are examples of its use in Ukraine's war against Russia.
Usage notes
The fuze is described in Kropyva only for Soviet-pattern systems. To obtain an air burst with 155 mm guns, proceed as follows:
The fuze has a scale of 450 divisions, corresponding to 90 s to functioning. Accordingly, 1 division is 0.2 s. The effective average burst height is 15 m above the target.
The fuze functioning time is set to correspond to the projectile's flight time. Increase the sight setting by 10–15 thousandths. After the first round, if a ground burst occurred, add another 10 thousandths to the sight setting, and so on until an air burst appears.
In rain, use the fuze only with the cap, which corresponds to high-explosive action in the event of contact with an obstacle. The timing mechanism will function just the same as with the cap removed.
Fuze Setting
Factory setting of the B90 fuze (sealed cap on the fuze) is high-explosive action. To set fragmentation action, unscrew the sealed cap with a wrench immediately before firing
Setting the B90 fuze for remote (time) action.
The full remote-action time of the fuze under stationary conditions is 90 s. Unscrew the sealed cap with a wrench immediately before firing. The fuze can be set for remote action using the ZI36 wrench or the ZI37 wrench.
The ZI36 setting wrench has a scale numbered from 10 to 450, with 440 divisions. If the ZI36 wrench is not available, the setting can be made with the ZI37 wrench using the scale on the main sleeve of the fuze, which has 88 divisions.
When firing in rain, to prevent premature bursts on the trajectory, do not remove the setting cap!
Oleh Syrota (Georgich©) for the Armed Forces of Ukraine / Entropia.com.ua
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