Different weapons for different effects
The Admiralty battle summary describes four bomb types selected for the attack. The weights identify weapon classes, not the weight of explosive inside each bomb. Its account of their intended effects belongs to the planning of the operation. YT-T22
| Bomb | Intended task |
|---|---|
| 1,600 lb AP | Penetrate main armour |
| 500 lb SAP | Penetrate the weather deck |
| 500 lb MC | Blast and splinters against exposed positions |
| 600 lb AS | Underwater damage from a near miss |
AP means armour-piercing; SAP, semi-armour-piercing; MC, medium-cased; and AS, anti-submarine. The last type was included for its possible effect beside a surface ship’s hull.
Height was part of the weapon’s performance
The summary’s planning note expected the 1,600-pound AP bomb to penetrate the main armour if released above 3,500 feet. It gave the 500-pound SAP bomb a different task: penetration of the two-inch weather deck from above 2,000 feet, with damage between decks. These were conditional expectations, not measurements of the penetrations actually achieved on 3 April. YT-T22
The MC bomb was intended to produce blast and splinters against exposed anti-aircraft positions. The AS bomb offered the prospect of underwater damage from a near miss, although a direct impact could instead detonate it against the superstructure.
In its account of the actual first strike, the summary reports releases between 3,000 and 1,200 feet; for the second, about 3,000 feet or slightly lower. Those figures fall below the height specified in the planning note for the heavy AP bomb. The distinction helps explain why reaching and hitting Tirpitz was not the same as achieving the hoped-for penetration. YT-T22
A load had to leave the deck
The original allocation distributed the different bomb types across each planned twenty-one-aircraft strike. A footnote records changes to that allocation: seven aircraft in the first strike and three in the second carried the heavy AP bombs, rather than five in each. YT-T22
Aircraft carrying the AS bombs took two rather than the originally proposed three because the wind was light. The Barracuda II table likewise lists two 600-pound bombs as that load. Flying conditions constrained the weapons that could be delivered.
Intended effect and actual damage
Tirpitz’s German damage account separates thirteen deck hits, one underwater hit and one near miss. Those categories should not be merged into fifteen direct hits, or treated as proof that every type of bomb achieved its intended effect. YT-T05
Follow Tungsten and the Return to Repair for the consequences. The much heavier Tallboy belongs to a later phase of the campaign.