No. 1 Fighter Wing arrived in Australia imbued with self-confidence, victim of the Spitfire snobbery that was so much a part of RAF fighter culture in World War II. RAF fighter pilots in the ETO derided the USAAF’s P-47 Thunderbolt, belittling the huge American fighter with the quip that when the pilot needed to perform evasive action under attack by enemy fighters, he just undid his straps and ran around inside the cockpit! This knee-jerk reaction negative impression ignored the P-47’s massively powerful Pratt and Whitney R-2800 engine and its associated turbocharger, which gave the big American machine superior performance in the tactically-critical altitude band above 25 000 feet.
When RAAF Spitfire pilots like Keith ‘Bluey’ Truscott were posted back to Australia for assignment to the RAAF’s newly-formed Kittyhawk squadrons, they similarly dismissed the heavy American fighter. Alongside the P-40’s trickier handling near the ground, Truscott admitted that it had good combat characteristics, but churlishly complained that you couldn’t ‘make it dance’ like a Spitfire. Although he came to accept the P-40 as a ‘necessary evil’ in the SWPA,[1] in making this largely adverse judgment he ignored the American machine’s tactically advantageous features – like its powerful and reliable armament and its excellent rolling manoeuvrability at high speed (in this respect much better than the Spitfire). With all his experience, he should have realised that air combat would not be decided by close-in dogfighting with enemy fighters, whether against the Germans over Europe or against the Japanese over New Guinea. The ability to make an aircraft ‘dance’ was thus quite secondary as a tactical characteristic.
To make matters worse, the Japanese had a fighter aircraft which could ‘dance’ even better than the Spitfire, a fact which was very well known even at the time, and about which the newly-arriving Spitfire pilots were warned. This was established beyond any doubt during comparison trials in August 1943 between one of the RAAF’s Spitfire VCs and a Model 32 Zero that had been captured in New Guinea and rebuilt at Eagle Farm airfield in Brisbane.
The Model 32 Zero, with its squared-off wingtips, was regularly encountered both over Darwin and New Guinea in 1943. Known to the allies by the reporting name ‘Hap’ to distinguish it from the round-wingtipped ‘Zeke’, the Model 32 was an improved model over the original Model 21 with which the Imperial Japanese Navy had fought its 1941-42 air offensives. The chief difference lay in its more powerful Mitsubishi Sakae 21 engine, which developed 1130 hp (as compared with 940 hp in the Model 21). The more powerful engine was heavier, requiring a reduction in fuel capacity from 518 litres to 470, and more thirsty; thus range was less than that of the earlier model. Both the newer and older types were encountered over Darwin.
Nonetheless, it was a Model 32 Zero that was captured and rebuilt, permitting the trials to occur in August 1943. The 1130hp of the Model 32’s Sakae 21 engine was quite comparable to the 1210 hp of the Spitfire’s Merlin 46, but the Model 32’s weight was much less – 5155 lb compared to the Spitfire’s 6883 lbs. As a result of this structural lightness, the Zero had both a superior power loading (4.5 lb/hp versus 5.6 lb/hp) and a lower wing loading (22 lb/ft2 versus 28 lb/ft2).
These differing technical characteristics determined the pattern of relative performance between the two machines, as shown by the tactical trials conducted by two experienced RAAF fighter pilots in flying trials conducted over three flying days[2]. Flight Lieutenant ‘Bardie’ Wawn DFC and Squadron Leader Les Jackson DFC flew against one another in both aircraft, and what they found was not encouraging.
They found that the Zero had a lower rated altitude than the Spitfire, 16 000 feet against 21 000 feet, which delivered the Spitfire a good speed advantage at height – it was 20 knots faster at 26 000 feet. However, as had already been noted by RAF Fighter Command in Europe, the Spitfire had relatively slow acceleration, and thus the Zero was able to stay behind the Spitfire within gun range while the Spitfire gradually accelerated away out of range. Even in a dive the Spitfire still accelerated too slowly to avoid the Zero’s gunfire. Climbing away was also not an option, as the Spitfire’s climb superiority was too slight (not to mention the slow acceleration problem once again).
The only offensive solution for the Spitfire was to attack from a height advantage, to maintain a high IAS on the firing pass, to fight on the dive and zoom, and to pull high speed G. Slowing down, or being caught while flying slowly, would clearly be very dangerous, for the Spitfire would be unable to evade. Above 20 000 feet, so long as the Spitfire started with a 3-4000 feet height advantage, the Spitfire could make dive and zoom attacks with impunity.
The height advantage of the Spitfire VC was also shown by the British machine’s superior operational ceiling. Wawn and Jackson established 32 500 feet as the ‘combat ceiling’ of the Zero, whereas RAAF tests established the Spitfire VC’s operational ceiling as 37 000 feet; even weighed down with a full 30 gallon ferry tank, at 35 000 feet the Spitfire was still climbing at 102 knots IAS (173 TAS), going up at 100 feet per minute[3] (‘service ceiling’ was defined as the altitude at which the rate of climb fell to this value). The superiority of the Spitfire’s ceiling is corroborated by its 5000 feet higher rated altitude, by 1 Fighter Wing’s demonstrated tactical employment of the Spitfire at heights up to 33 500 feet, and by the Zero pilots’ avoidance of the height band above 30 000. The pattern established in these tests confirmed the findings of operational experience over Darwin, where the Spitfires were always able to dominate the upper height band without Japanese challenge.
The Zero developed its maximum speed of 291 knots at its rated altitude of 16 000 feet. The Spitfire produced 290 knots at 15 000 feet, confirming that below 20 000 feet the two types were more evenly matched in speed performance. Given the Zero’s much superior acceleration, in practice this meant that the advantage tipped more heavily in favour of the Zero at these lower altitudes. In comparative tests at 17 000 feet, the Spitfire was again unable to safely draw away from the Zero. The unanimous conclusion of Wawn and Jackson was that ‘the Spitfire is outclassed by the Hap at all heights up to 20,000 feet’.
As was already well known, the Zero had all the advantages in combat manoeuvrability at slower speeds. This was a product of the Japanese machine’s superior power loading and lower wing loading. The Zero stalled at only 55 knots, whereas in clean configuration the Spitfire stalled at 73. Being able to fly more slowly while still under complete control meant the Zero could fly tighter turns without stalling out. The stall speeds cited apply to straight and level flight at 1G – hardly a realistic scenario in combat, where pilots would typically stall out of accelerated turns. In a modest 3G turn, the Spitfire would stall at 130 knots IAS, which equates to a TAS of 242 knots at 20 000 feet. At 6G (a hard turn or pull out at high speed, with the pilot blacking out), the Spitfire stalled at 184 knots IAS, which equated to 257 knots TAS at 20 000 feet, and 294 knots at 30 000. The latter was only 11 knots less than the Spitfire’s maximum speed at that height (at the emergency power settings of 3000 rpm and plus 2 ½ pounds boost), so it is clear that as height increased, the pilot found himself stuck in an increasingly narrow corner of the flight envelope, until any attempt to pull G would result in an instant high speed stall. This helps to explain the high incidence of Spitfires stalling and spinning out of combat turns over Darwin in 1943.
By contrast, the Zero’s lighter weight meant that it would always be superior in all tight manoeuvres. Obviously, the Zero also stalled out under G, but the tests showed it to have superb handling characteristics in hard turns, with no tendency to spin out of high speed stalls (implying that it was superior to the Spitfire in this respect). Although Spitfires endeared themselves to pilots by their sweet flying qualities, it is clear that the Zero too had impeccable manners.
If a Spitfire followed a Zero around in a loop, it would stall out at the top, and could only stay behind the Zero for ¾ of a horizontal turn. In short, it was too easy for a Zero to evade a Spitfire at medium altitudes and below, by simply performing any vertical manoeuvre or hard turn. This meant it would be very difficult for a Spitfire to get a shot at a manoeuvring Zero. The only practical firing opportunity for Spitfire pilots would come in a bounce.
Neither aircraft had a good roll rate at high speed, due to their ailerons locking almost solid in the airflow. However, in this respect the Zero was even worse than the Spitfire, which permitted a glimmer of encouragement for the Spitfire pilot: the Zero could not get into a firing position behind the Spitfire if the latter evaded in diving aileron turns at high speed. Other than the downward break, no other evasive manoeuvre by the Spitfire was likely to work, although a vertically-banked climbing turn was difficult for the Zero to follow. Otherwise, the Zero could follow the Spitfire through any manoeuvre below 220 knots, and could use its slow turning advantage to get onto the Spitfire’s tail after 2 ½ hard turns.
It was only at higher speeds that the Spitfire started to enjoy a relative advantage. Because the Zero’s controls stiffened up even more rapidly than the Spitfire’s, the Zero had great difficulty in following the Spitfire through high speed manoeuvres where the pilot pulled a lot of G. From about 290 knots, the Zero had great difficulty following the Spitfire through diving aileron rolls. The conclusion was that the Spitfire was more manoeuvrable above 220 knots, while the Zero was the better below that speed. Reflecting this set of opposite characteristics was the fact that the Zero’s standard evasive manoeuvre was the very opposite to that of the Spitfire – upwards rather than downwards, in the form either of a climbing turn or a vertical aerobatic manoeuvre like a loop, stall turn or Immelmann.
Overall, the summary from the comparative trials was not encouraging:
‘Both pilots consider the Spitfire is outclassed by the Hap at all heights up to 20 000 feet…The Spitfire does not possess any outstanding qualifications which permit it to gain an advantage over the Hap in equal circumstances.’[5]
The conclusions of Wawn and Jackson only corroborated the earlier evaluation conducted by 1 Fighter Wing HQ[6] after combat experience over Darwin, which found that the Spitfire had a higher maximum speed, that it was more manoeuvrable at high speed, and that it could be dived to a greater speed. It followed that the only sensible offensive tactics were the dive from height followed by a zoom climb for a re-attack. The recommended evasive tactic when under attack was to break downwards into a vertical dive at full power, while yawing the aircraft violently by uncoordinated use of the rudder and/or ailerons to put the Zero pilot off his aim. Once the speed had built up (presumably 300 knots), the pilot should start rolling into downward aileron turns to obtain a clean separation from the Zero.
Rightfully, a whole generation of pilots learned to treasure the Spitfire for its delightful response to aerobatic manoeuvres and its handiness as a dogfighter. However, it is odd that they had continued to esteem these qualities over those of other fighters in spite of the fact that they were of only secondary importance tactically. As the Germans had showed the RAF fighter squadrons, the most decisive superiority in fighter combat came through some combination of height, speed, and firepower, not tight turning or manoeuvrability. Thus it is doubly ironic that the Spitfire’s reputation would habitually be established by reference to archaic, non-tactical criteria, and that the new Japanese opponent would trump every one of the Spitfire’s purported trademark virtues: in effect, ‘whatever you can do, I can do better’.
However, despite the gloomy overall assessment provided by the comparative tests, the relative situation was not unfavourable to the Spitfire. Given that the strong fighter and AA defence over Darwin forced the Japanese to penetrate Australian airspace above 25 000 feet, the Zeros were thereby forced to play to the Spitfire’s strengths. Moreover, given the tactical situation of intercepting bomber formations, the Spitfires would generally be coming down in a high speed dive, which was also advantageous. 1 Fighter Wing’s recommended tactics at this point were correct: either to zoom back up after firing or disengage by continuing the high speed dive downwards. Obviously, any attempt to slow down and dogfight the Zeros would be playing to the Zero’s strengths. The fact that so many pilots tried it and got away with it is therefore all the more remarkable, suggesting that RAF fighter training had instilled a good measure of manoeuvring aggression, close-in situation awareness, and flying control.
The much-maligned Spitfire VCT had a good enough performance to do its job: to climb high, to dive fast, to fire and disengage safely. Indeed, in these respects it had similar tactical characteristics to other early-war allied fighter aircraft – such as the P-39, P-40, and F4F Wildcat – in that it possessed a clear superiority in one tactical mode: diving fast into the attack and then performing rolling downward evasion. On top of that, it shared with the F4F the ability to climb above 30 000 feet – the tactical vantage point from which attacks were delivered. These were its most relevant tactical characteristics. In that sense, the Spitfire was no more and no less than a typical allied fighter of the earlier part of World War II – good enough to do its job, but not good enough to establish superiority over the enemy.
[1] Ivan Southall (1958) Bluey Truscott, Sydney, p.153-156.
[2] 14, 17-18.8.1942.
[3] NAA A11093: 452/A58 PART 1.
[4] NAA A11093: 452/A58 Part 1.
[5] NAA A1196 1/501/505.
[6] NAA A1196: 1/501/505.
LINK
LINK
No comments:
Post a Comment