A convoy group built around two helicopter sloops and a merchant aviation ship could combine roughly sixteen aircraft, keeping several airborne while others stood ready or underwent maintenance. The helicopters need not match a Sunderland's bomb load because their strength comes from persistent local coverage and rapid concentration. A surfaced U-boat might defeat one lightly armed patrol aircraft, but firing exposes its position and draws several more aircraft carrying rockets or depth charges. That contest also diverts the submarine from attacking merchant shipping, which is its actual mission. Heavier German losses and fewer successes in 1939-41 could weaken expansion of the U-boat arm and reduce political support for later advanced submarines such as the Type XXI.
Chapter · 1:14:03-1:18:09
Helicopter convoys overwhelm surface-operating U-boats
Sloops and a converted merchant flagship could sustain enough armed helicopters to deny U-boats safe surface approaches around a convoy.