Lt Cdr John Moffat RN was one of the Swordfish pilots from HMS Ark Royal that attacked the Bismarck and is generally credited with launching the torpedo that damaged her steering gear and, consequently led to her demise at the hands of the British cruisers, which should certainly mean that he knows what he’s talking about. In his 2009 book “I Sank the Bismarck”, he had this to say about the Fairey Swordfish, which explains some of its success:
This aircraft (the Swordfish) seemed like a hangover from the 1920s, although it had actually come into service in 1936. It was a biplane, and had all sorts of struts and wires reminiscent of the First World War planes like the Avro 504 that had first excited my interest in flying. But the Battle of Britain was being fought by fast monoplanes - Hurricanes and Spitfires. They were all metal, whereas the greater part of the Swordfish, the wings and the rear fuselage, were canvas covered. It was powered by a single radial engine that gave it a top speed of barely 110 miles per hour. The Spitfire could manage over 300 quite easily. The Swordfish was a big aircraft, with a crew of three. The pilot sat in a forward open cockpit, which was high above the centre line and gave a good field of view. Behind was another cockpit, set lower in the fuselage, in which there was first the observer/navigator; then behind him the telegraphist air gunner, or TAG, who worked the radio and could fire a rear-pointed drum-fed Lewis gun. Apart from this, there was a forward-firing machine gun mounted in the fuselage behind the engine. The huge wing area gave the Swordfish the ability to carry a bomb load of almost 2,000lb, which was impressive for a single-engined plane. It was manoeuvrable at slow speed and could pull out of a dive without any trouble.
I felt that I was riding a cart horse instead of a steeplechaser at first, but the more I flew it, the more I began to appreciate its qualities. It was nicknamed the ‘Stringbag’. Several reasons are given for this, the most obvious being that at first glance it looks as though it is held together by string. This is deceptive. The main struts were made out of stainless steel, the rigging was very strong steel cable, and the frames were made of steel and duralumin, an aluminium alloy produced for aircraft production. No, I believe the Stringbag got its name because, like the old lady’s shopping bag, it expanded to accommodate whatever was demanded of it. It carried bombs, depth-charges, torpedoes, smoke flares, and they even mounted sixteen rockets under the wings in the later stages of the war. There are stories of some squadrons moving rapidly from airstrip to airstrip in the desert in North Africa, securing motorbikes underneath the fuselage of their Swordfish and then carrying them to a new location. It was a tough plane and could take an awful lot of damage, as many aircrew were to discover and be grateful for. It’s low speed was also an asset, it seemed, as our instructors told stories of Swordfish in the Norwegian campaign being attacked by Messerschmitt 109s. The British pilots employed the tactic of making 180-degree turns at sea level towards the attacking plane. The Swordfish had a much smaller turning circle than any fast fighter, and moreover it had such an advantageous lift ratio that you could reduce its speed to just 70 knots in the turn and it would continue on a perfect line. Most planes need more power to complete a turn, but not the Swordfish. The hapless Messerschmitt pilot would not know why his target had suddenly disappeared from view as he sped past.
I particularly like his explanation of why the Swordfish was nicknamed Stringbag, which wasn’t what I had previously been led to believe.
Sadly, John Moffat is no longer with us, as he died in December 2016 at the age of 97. In his sixties, after 40 years, he began flying again and celebrated his 90th birthday in June 2009 by performing aerobatics in a light aircraft. He was often the guest of honour at Fleet Air Arm Taranto Night dinners, which celebrate the attack on the Italian fleet in Taranto harbour in November 1940, when Swordfish sank several Italian capital ships. Although he hadn’t taken part in the raid, he was one of the very few remaining WWII Swordfish pilots alive at that time.
Visiting the RN Historic Flight in 2008 to get re-acquainted with the Swordfish
As guest of honour at Ark Royal's final Taranto Night event in 2010
One point only touched upon - the Swordfish was slow which meant that it could fly low near the surface of the water - low and slow was good for aiming and launching torpedoes. US torpedo bombers for example would have to slow considerably as they approached their target to get a good launch. This made them difficult to control.
https://falkeeinsgreatplanes.blogspot.com/2011/03/fairey-swordfish-bibliography.html