LESSONS FOR THE BOMB AIMER No.6 - ANTI-SUBMARINE BOMBING [Main Title]
Technical instructional film for bomb aimers, focusing on bombing submarines.
Reel 1: - Part 1 - Diagrammatic explanation of principles of bombing submarines – essential that the bomb detonates within a few feet of the hull – 100lb bomb effective within four feet, 250lb is nine feet and 500lb bomb is fourteen feet. Accuracy is essential for effectiveness of single bomb. Beam attack more effective than a fore/aft attack. Breakdown of example bomb load. Various bomb “stick” effectiveness explained. Example of AS bomb fitted with No.30 Pistol Fuze has delay of 1 second after impact with water. “The Lethal Column” - bomb is said to posses a “lethal column” around it's trajectory – the cross sectional area of the column is equal to the vulnerable area of the target from the direction of attack – vulnerable areas described. Use of 100lb bombs may be more effective than larger bombs due to closer spacing and overlap of blast areas.
Reel 2: - Part 2 - “Countermining” - anticipates the normal delay action of individual fuzes and disturbs the level of the zone of normal detonation. i”The Angle Of Dive” - shallow dive is best form of attack. More than 30º makes placing of “stick” more difficult. Various elements to ensure a good dive angle. “Release Height When Submarine is Surfaced” - releasing bombs on surfaced subs. Risks of aircraft being damaged by bomb fragments at less than 600ft. Ensuring sighting angles remain accurate. “Aiming” - aircraft ring bead sight used to aim. For Swordfish aircraft, ideal angle is 30º and 150 knots. “Relative Wind” - up to now factors for sighting have been under “Still Air” conditions (“No Wind” Sighting Point). Sighting points for following, head and sidewinds. Allowance for wind is known as “Angular Aim Off”/ For Relative Wind and equals quarter degree per knot.