Target angle Angle on the bow provided the basis for submarine attack decisions through the world wars. When angle on the bow was less than 90° , the submarine would continue a submerged approach toward the target to launch torpedoes when angle on the bow increased to 90° indicating the minimum range torpedo launch opportunity for the submarine with the given target course and speed. Unless the target was already within torpedo range, angle on the bow greater than 90° required the submarine to attempt to surface and run around the target beyond visual range to submerge ahead of the target. As
Type 90 AFV rear; the latter open outwards. In each side of the hull there are three firing ports with periscopes. On either side of the forward hull, a cluster of four 76 mm smoke grenade dischargers is mounted. The vehicle is fully amphibious, a folding trim board stowed at the front of the hull needs to be raised, and the vehicle can then propel itself in the water using its tracks. Standard equipment includes an NBC system, a Type 889 radio, and a Type 803 intercom system. Type 90 AFV The Type 90 is an armoured fighting vehicle produced by Chinese company