Battle of Atlantic , May-July 1941 . RAF Coastal Command Re-Organises

The British attack on the U-boat force in Atlantic waters by aircraft of RAF Coastal Command had produced virtually zero kills by June 1, 1941. Two Sunderlands had shared credit with surface ships in the destruction of two U-boats (U-26, U-55,) but no Coastal Command aircraft flying in the Atlantic area had sunk a U-boat unassisted.

There were numerous reasons for this abysmal showing. Chief among these was that Coastal Command remained a poor stepchild of the RAF, still in third place in weaponry, electronics, and manpower. As one consequence, Coastal Command was still unable to mount a credible attack on the U-boat force. An official study showed that in mid-1941 Coastal Command had only about two hundred ASW aircraft in frontline squadrons.

RAF aircraft in the Mediterranean had sunk two Italian submarines (Argonauta, Rubino) unassisted and shared credit for two others (Gondar, Durbo) with British surface ships. The principal contribution Coastal Command had made thus far in the Battle of the Atlantic was to thwart single and pack U-boat operations in the Northwest Approaches and Icelandic waters out to about 300 miles. This was primarily the doing of the hundred American-built twin-engine Lockheed Hudsons flying on convoy escort or offensive ASW patrols. However, the Hudsons could carry only three or four 250-pound depth charges and did not have sufficient fuel to safely patrol much beyond 300 miles or to loiter for very long at that distance from home. The best they could do was to force a U-boat to submerge and hold it down. This was also true of the forty British-built twin-engine Whitleys. They could carry twice the depth-charge load of the Hudsons (six), but they could not fly on one engine, a severe handicap for over-water operations. Hence the Hudsons and Whitleys, which made up about 70 percent of Coastal Command’s frontline strength, were not really satisfactory for offensive actions against U-boats.


Lockheed Hudson

What Coastal Command urgently needed for convoy escort and offensive ASW patrols was a long-range aircraft with a large bomb load. The twenty four-engine Sunderland flying boats partially filled that need. They could carry eight 250-pound depth charges on patrols out to about 700 miles. However, the huge Sunderland was not an efficient aircraft; its four engines required much maintenance. A Coastal Command study showed that each of the Sunderlands flew an average of only two sorties per month. The British war industry would continue producing Sunderlands on a modest scale, but no one favored anything more than that.


Short Sunderland

Better yet was the American-built PBY Catalina flying boat (which British named Canso), of which Coastal Command had thirty. They could carry twice the bomb load of a Sunderland (sixteen 250-pound depth charges) out to about 900 miles. The Americans were gearing up to produce Catalinas at a high rate, but in view of its two-ocean force deployment and large new responsibilities in the Atlantic, the U.S. Navy had first call on Catalinas and only a trickle could be diverted to the British and Canadians. At the end of 1941, Coastal Command still had only thirty-six Catalinas in four frontline squadrons (209, 210, 240, 413) based in and around the British Isles.

PBY Catalina

PBY Catalina

In June 1941, Coastal Command got a new chief, Philip Joubert de la Ferté, replacing Bowhill. He urged an expansion of Coastal Command to provide for increased emphasis on offensive patrolling, especially in the Bay of Biscay, a choke point through which U-boats had to transit inbound and outbound to French bases. However, Bomber Command, gearing up for the supposed war-winning strategic air assault on Germany, stoutly resisted the diversion of any aircraft to Coastal Command.

Nonetheless, for a brief time Joubert appeared to have won at least part of his case. The War Cabinet allotted Coastal Command the first nine of the new four-engine B-24 Liberator bombers arriving from America. The B-24 had about the same operating radius as a Catalina (900 to 1,000 miles), but it was twice as fast (205 knots versus 105 knots), could carry twice the bomb load (8,000 pounds versus 4,000 pounds), was more rugged and more heavily armed with defensive machine guns and 20mm cannons, and, of course, it was a land plane that could base at existing airfields. These nine B-24s went to a new Coastal Command squadron, 120, based at Nutt’s Corner, Northern Ireland, commanded by Terence M. Bulloch, but all other B-24s arriving from America went to RAF Bomber Command.

Joubert turned to the scientific community for assistance to improve Coastal Command’s operations, especially the miserable U-boat kill rate. The Admiralty sent him a brilliant physicist, Patrick M. S. Blackett, who was to win a Nobel Prize in the postwar years. Utilizing a statistically oriented method of applied science initially devised for the RAF, which came to be called “Operations Research,” Blackett and a small team analyzed thousands of U-boat contact and attack reports. Based on this analysis (“quantitative, analytic thinking with empirical checking”), the Blackett team advised that:

• Navigation in Coastal Command was appallingly bad. Aircraft crews seldom knew precisely where they were, did not actually patrol designated areas, and too often failed to meet convoys they were assigned to escort.

• The 1.5-meter-wavelength ASV II radar, installed in three quarters of Coastal Command’s frontline aircraft, was not being properly exploited. Radar operators were undertrained and overworked. Radar sets were not properly maintained and calibrated.

• Aircraft were flying too high to get the most from the sets. Based on exaggerated claims of radar proponents, air crews expected too much of ASV II radar, and when it failed to perform as advertised, they denounced it.

• In the majority of U-boat contacts, the Germans saw the aircraft first and dived to safety. Aircraft spent too much time and too many assets futilely depth-charging elusive targets.

• The usual depth settings on the standard 250-pound depth charge were too deep and the explosive in the warhead was too feeble.

• A prevailing view that a monster 2,000-pound depth charge was required to compensate for aiming errors was absolutely wrong.

The Blackett reports contained many recommendations to correct the deficiencies. Among them: thorough training for navigators and radar-maintenance personnel and radar operators, and a lowering of expectations about the sets; comfortable work stations and frequent eye rest for radar operators; an altitude limit of 4,000 feet for convoy spotting and 2,000 feet for U-boat spotting when using radar; the use of beacon signals to improve convoy locating; the camouflaging of the undersides of aircraft with white paint to decrease visibility; the mounting of binoculars on pedestals for daytime searching; a twenty-five-foot fuse for depth charges; a larger “stick” of 100-pound depth charges utilizing the more powerful explosive RDX or Torpex (TNT and cyclonite, enhanced with aluminum powder).

Some of these recommendations touched off intense controversy. The most heated was the debate over depth-charge size. Most airmen refused to believe that larger numbers of small depth charges were preferable to a smaller number of oneton “killer” depth charges. As a result, R&D on the 2,000-pound and also less powerful weaponry, as well as a depth-charge bombsight, was pursued. Meanwhile, the standard airborne ASW weapon remained the 250-pound depth charge dropped by eye. However, Blackett’s recommendations that the spacing of the stick be lengthened threefold and the warhead be beefed up with Torpex, and the twenty-five-foot fuse were followed.

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