although it was not stressed for such tactics, and from time to time it disintegrated while bombing.
Generally, glide bombing (attack at a shallower angle) was practiced as a less straining alternative to dive bombing, since it still gave a better aim than level bombing. During the early part of the Second World War, the distinction between the two was not always drawn. In Norway, for example, until the Germans had airfields ashore they used long-range bombers (Ju 88s) to attack the British fleet offshore. Those aircraft often made shallow (glide-bombing) dives. British long-range barrage tactics often frustrated them. By way of contrast, the short-range Stuka (Ju 87) made true dive-bombing (near-vertical) approaches.
Aircraft structural strength limited the weight of the dive bomb, the heaviest probably being the German 1600lb armour-piercing bomb. When the Royal Navy’s Fleet Air Arm attacked the battleship Tirpitz in 1944, pilots kept their bombs on board as long as they could to ensure hits. They did not give the bombs enough altitude to accelerate enough to penetrate the ship’s protective decks. In 1941 the US Navy became interested in a solution in the form of a rocket boost, but it did not materialise. Thus dive bombing was unlikely to sink a battleship, although it might do significant damage. By manoeuvring, a diving pilot could keep his bomb pointed at a manoeuvring warship. His chance of hitting was far better than that of a level bomber. The closer the dive bomber came to a vertical dive, the closer the bomb would follow where the bomber’s nose pointed. The further from the vertical, the more important it was for the bombsight to compensate for bomb ballistics. Because it used near-vertical tactics, the US Navy relied on a simple tube gunsight. Because they attacked at a shallower angle, they required a more elaborate bombsight (development of which lagged badly in 1932–8).
The Curtiss Helldiver (SB2C) was bought ‘off the drawing board’ to replace the Dauntless in the autumn of 1940 due to the obvious threat of war. The Helldiver was designed for a 1938 competition in which the engine was the next-generation (after the Dauntless) R-2600 producing 1700hp, carrying the standard 1000lb bomb internally. The urgent order and equally urgent preparation for large-scale production made it difficult or impossible to cure defects in the design, ultimately limited strength (Helldivers sometimes disintegrated while diving, and sometimes even when sitting on a runway) and limited longitudinal stability (Helldiver dimensions were set by a requirement that two be able to ride a 41ft × 48ft carrier elevator). Modifications increased weight to the point where the Helldiver was little faster than a Dauntless, and pilots much preferred the earlier aircraft: the Helldiver was designed to operate at 11,900lbs, but at the end of 1944 it weighed 16,800lbs. Power did not increase proportionately; the later R-2600 produced 1900hp. From an attack point of view, the important advantage of the Helldiver was its large bomb bay, which made it possible to increase the bomb load as BuAer realised in 1942 that the 1000lb bomb was not enough. The bomb bay could accommodate either two 1000lb or one 1600lb AP bomb, and a special adaptor made by Curtiss made it possible to carry either a 2000lb bomb or a torpedo (which was partly external). Note that the 1600lb AP bomb did not figure in the 1944–5 attacks on the Japanese super-battleships.
Pre-Second World War exercises suggested that dive bombing would often take ships entirely by surprise. Patrolling fighters often found it difficult to follow the dive bomber into its low-altitude escape after releasing its bomb. A dive bomber was a very difficult anti-aircraft target, because its altitude was changing so rapidly. For example, a bomber diving at 300kts (which was not fast for 1941) would complete a dive from 12,000ft to bomb release in only 20 seconds. The US Navy seems to have been unique in adequately simulating dive bombers using radio-controlled targets (the British Queen Bee could not dive-bomb). Lack of realistic experience may have made the Royal Navy unduly optimistic about its ability to deal with this threat, although it was certainly aware of it. German use of dive bombers, particularly in the Mediterranean, seem to have been a terrifying surprise.
A single dive bomber was bad enough, but the tactic lent itself to multiple simultaneous attacks from different directions, because attacks were over so quickly that pilots did not have to make much allowance for the movement of their targets. Moreover, dive bombing was far more accurate than level bombing. In June 1937 the Germans tried both kinds of attack against the radio-controlled target ship Zahringen. Level bombers scored 2 per cent hits; dive bombers scored 40 per cent, and the Inspector for Naval Airmen spoke of the ‘amazing superiority of the Stuka over the ordinary bomber’.29 In 1944 a German officer commented sourly that this was true only as long as there was not a lot of anti-aircraft fire concentrated around the target, because in that case an aircraft diving straight down made an excellent target.
This Barracuda was sent to the US Navy’s test field at Patuxent River for 1944 tests. Because the Barracuda did not function well in hot, humid weather, the British Pacific Fleet was equipped with Avengers instead, even though they did not offer dive-bombing capability. (David Hobbs)
As it began to rearm in 1933–4, the Royal Navy came to realise that it could not match the numbers of carrier aircraft in the Japanese navy, which it considered its most likely enemy. In November 1934 the Admiralty made the case for a carrier-based dive bomber specifically to gain air superiority by disabling or sinking Japanese carriers.30 As a fallback, the dive bomber could be used as a fleet fighter, but dive-bombing performance was much more important than fighter performance. A formal specification (O.27/34) issued that December produced the Blackburn Skua. It made excellent sense as long as the main air threat to a fleet at sea came from enemy carriers. Given the rapid advance in aircraft performance at the time, the value of fleet fighters was declining. Screening ships could no longer provide enough warning to launch interceptors, and no carrier could support a sustained fighter patrol. The new high-performance fighters were minimum airframes wrapped around the most powerful lightweight engines, so they lacked the endurance to remain on patrol for long. That was a reason that fighter direction based on early detection was critical for the Battle of Britain a few years later.
Barracudas on Formidable being armed with 1600lb AP bombs during August 1944 strikes against the German battleship Tirpitz (Operation ‘Goodwood’: strikes on 17 July and 22, 24 and 29 August). The aircraft in the background are US-supplied Corsairs. In addition to her anti-aircraft battery, in resisting the Fleet Air Arm attacks Tirpitz fired both her 15in and her 5.9in LA guns in barrage mode, with time-fused HE ammunition (German accounts give the numbers of rounds fired). (David Hobbs)
Unfortunately for the Royal Navy, by about 1935–6 it seemed that a future war might well be fought in European waters, where an enemy could deploy large numbers of aircraft at shore bases. No naval dive-bomber force could neutralise those bases, although it turned out that intense air attacks could shut a few of them down for brief periods. Since the Royal Navy could not secure air superiority under these circumstances, it adopted armoured flight deck (actually armoured hangar) carriers whose limited aircraft capacity was devoted entirely to strike aircraft. A carrier facing air attack would strike all of her aircraft below, into the armoured hangar. Fleet anti-aircraft guns would be the sole defence. It seems to have been assumed that this was a reasonable choice, that British anti-aircraft gunnery would make attacks on the battle fleet difficult at best. In practice the Royal Navy was unwilling to depend entirely on its guns, so it continued to buy small numbers of fighters – adapted Gloster Gladiators and then the purpose-built Fairey Fulmar. It is not clear whether those responsible realised that the advent of radar would soon make shipboard fighters effective.31
By 1944 the Royal Navy had a fully effective dive bomber in the form of the Fairey Barracuda, and it was used in 1944 strikes against the German battleship Tirpitz. On 3 April (Operation ‘Tungsten’) forty Barracudas in two waves escorted by eighty-one fighters) achieved complete surprise.
