RAF Fighter Aircraft
I must now give a brief account of the characteristics of the aircraft commonly employed on both sides. As regards the fighter types available in the Command, the bulk of the force consisted of Hurricanes and Spitfires; the former were beginning to be outmoded by their German counterparts. They were comparatively slow and their performance and manoeuvrability were somewhat inadequate at altitudes above 20,000 ft. The Spitfires were equal or superior to anything which the Germans possessed at the beginning of the Battle.
In the aforementioned publication entitled The Battle of Britain, issued by the Air Ministry, the speed of the Hurricane is seriously over-rated at 335 m.p.h. I carried out a series of trials to obtain the absolute and comparative speeds of Hurricanes and Spitfires at optimum heights. Naturally the speeds of individual aircraft varied slightly, but the average speed of six Hurricanes came out at about 305 m.p.h.
The Hurricanes and Spitfires had bullet-proof windscreens and front armour between the top of the engine and the windscreen. They also had rear armour directly behind the pilot, which was previously prepared and fitted as soon as we began to meet the German fighters. The early adoption of armour gave us an initial advantage over the Germans, but they were quick to imitate our methods. While German aircraft remained unarmoured, I think it is now generally agreed that the single-seater multi-gun fighter with fixed guns was the most efficient type which could have been produced for day fighting. The Defiant, after some striking initial successes, proved to be too expensive in use against fighters and was relegated to night work and to the attack of unescorted bombers. It had two serious disabilities; firstly, the brain flying the aeroplane was not the brain firing the guns: the guns could not fire within 16 degrees of the line of flight of the aeroplane and the gunner was distracted from his task by having to direct the pilot through the communication set. Secondly, the guns could not be fired below the horizontal, and it was therefore necessary to keep below the enemy. When beset by superior numbers of fighters the best course to pursue was to form a descending spiral, so that one or more Defiants should always be in a position to bring effective fire to bear. Such tactics were, however, essentially defensive, and the formation sometimes got broken up before they could be adopted. In practice, the Defiants suffered such heavy losses that it was necessary to relegate them to night fighting, or to the attack of unescorted bombers.
The Blenheim was also unsuitable for day-time combat with fighters, owing to its low speed and lack of manoeuvrability.
One Squadron of Gladiators was still in use in the Command. As explained above, the organisation of No. 10 Group was not complete, and there was no large aerodrome close enough to Plymouth to allow of direct protection being given to that town and to the Dockyard at Devonport. A squadron of Gladiators was therefore located at a small aerodrome called Roborough in the immediate vicinity. The Gladiators, though slow by modern standards, were very manoeuvrable, and had given good results in Norway by deflection shooting in the defence of fixed objectives, where the bombers could not avoid the Gladiators if they were to reach their targets.
Some American single-seater aircraft were in Great Britain, but the types then available were deficient in performance and fire power and were not employed to any material extent.
The Whirlwind raised high hopes in some quarters. It claimed a very high top speed and carried 4 cannon guns. It had, however, a totally inadequate service ceiling (about 25,000 ft.) and a poor performance at that altitude. It also suffered from a continuous series of teething troubles, and the single Squadron equipped with this type was never fit for operations in my time.
A great deal of discussion took place before and in the early stages of the war as to the best method of harmonisation of the guns of an 8-gun fighter: that is to say the direction, in relation to the longitudinal axis of the aircraft, in which each gun should be pointed in order to get the best results.
There were three schools of thought. One maintained that the lines of fire should be dispersed so that the largest possible “beaten zone” might be formed and one gun (but not more than one) would always be on the target. The second held that the guns should be left parallel and so would always cover an elongated zone corresponding with the vulnerable parts of a bomber (engines, tanks and fuselage). The third demanded concentration of the fire of all guns at a point.
Arguments were produced in favour of all three methods of harmonisation, but in practice it was found that concentration of fire gave the best results. Guns were harmonised so that their lines of fire converged on a point 250 yards distant: fire was therefore effective up to about 500 yards, where the lines of fire had opened out again to their original intervals after crossing at the point of concentration.
It was very desirable to get data as to the actual ranges at which fire effect had been obtained. The reflector sight contained a rough range-finder which the range of an aircraft of known span could be determined if it was approached from astern, but, in spite of this, pilots, in the heat of action, generally underestimated the ranges at which they fired.
Cinema guns, invaluable for training purposes, were used in combat also; and many striking pictures were obtained, from which valuable lessons were learned.
The types of ammunition used in the guns varied during the course of the Battle. It was necessary to include some incendiary ammunition, but the type originally available gave a distinct smoke-tracer effect. Now tracer ammunition in fixed guns at any but very short range gives very misleading indications, and I wished pilots to use their sights properly and not to rely on tracer indications. (The above remarks do not apply at night, nor to free guns, where tracer is essential for one of the methods taught for aiming.)
During the Battle, de Wilde ammunition became available in increasing quantities. This was an incendiary ammunition without any flame or smoke trace, and it was extremely popular with pilots, who attributed to it almost magical properties. 8-gun Fighters, of course, were always liable to be sent up at night, and it was therefore desirable to retain some-of the older types of incendiary bullets. These were preferred to the “tracer” proper, which gave too bright a flame at night.
A typical arrangement, therefore, was: old-type incendiary in the 2 outer guns, de Wilde in one gun while supplies were limited, Armour piercing in 2 guns, and ball in the other 3.
Increasingly throughout the Battle had the importance of a high ceiling been manifested. It is by no means necessary that every fighter shall have its best performance at stratospheric heights; any such policy would result in a loss of performance at lower altitude, and we must never lose sight of the basic principle that the fighter exists for the purpose of shooting down bombers, and that its encounters with other fighters are incidental to this process.
There are, nevertheless, arguments for giving to a percentage of fighters a ceiling (determinable by specific physiological tests) above which no enemy can climb without the use of pressure cabins. Just as the “weather gauge” was often the determining factor in the tactics of sailing ships, so the ” height gauge” was often crucial in air combat. Exhaust-driven turbo-superchargers have certain advantages over gear-driven blowers at great height, and should be considered for adoption in spite of their disadvantages.
It is very difficult to give any kind of concise description, of the types of enemy aircraft used during the Battle. The Germans, while adhering to broad standard types, were continually modifying and improving them by fitting more powerful engines and altering the armament. The original Messerschmitt 109, for instance, had a performance comparable with that of the Hurricane, but the latest type could compete with the Spitfire, and had a better ceiling. Some of them had 4 machine guns and others had 2 machine guns and 2 cannon. Some of them were fitted to carry bombs and some were not.
The Messerschmitt 110 was a twin-engined fighter designed primarily for escorting bombers and used also as a fighter-bomber. It was somewhat faster than the Hurricane, but naturally much less manoeuvrable than the single-engined types. Its usual armament was 2 fixed cannon and 4 machine guns firing forward, and one free machine gun firing to the rear. Our pilots regarded it as a less formidable opponent than the later types of Me 109.
The Heinkel 113 Fighter made its appearance in limited numbers during the Battle. It was a single seater, generally resembling the Me 109. Its main attributes were high performance and ceiling, so that it was generally used in the highest of the several layers in which attacking formations were usually built up.
The Junkers 87 was a single-engined dive bomber. With top speed well under 250 m.p.h., its performance was low. It had 2 fixed machine guns firing forward and one free gun firing to the rear. When it was able to operate undisturbed by fighters it was the Germans’ most efficient bomber against land or sea targets owing to the great accuracy with which it dropped its bombs; but when it was caught by fighters it was nothing short of a death-trap, and formations of Ju 87’s were practically annihilated on several occasions.
The Heinkel 111 and the various types of Dornier (17, 17 Z and 215) constituted the main element of the German striking force. They were twin-engined aircraft and were generally similar, although the former was slightly the larger. Their speed was something over 250 m.p.h., and their armament consisted normally (but not always) of 4 free machine guns firing backwards and one firing forwards. Their radius of action varied with tankage and bomb load, but, if necessary, all objectives in England and Northern Ireland could be reached from aerodromes in France.
The Junkers 88 was the most modern of the German bombers. It also was a twin-engined type with a performance of about 290 m.p.h. Its armament was generally similar to that of the He 111 and the Dormers and it had a slightly longer range. It could be used on occasions as a dive bomber and, though probably somewhat less accurate than the Ju 87, was much less vulnerable owing to its superior performance and armament.
It has been estimated that the Germans sent over, on an average throughout the Battle, four fighters to each bomber or fighter-bomber, but any such estimate must be very rough.
I must emphasise, throughout, the extreme versatility of the German methods both in the timing and direction of their attacks, and in the tactical formations and methods employed.
They enjoyed the great advantage of having a wide front from which attacks could be delivered. First a blow would be delivered from Calais, perhaps against London; then after a carefully-timed interval, when 11 Group Fighters might be expected to be at the end of their petrol endurance, a heavy attack would be made on Southampton and Portland. Other attacks, after being built up to formidable dimensions, would prove to be only feints, and the bombers would turn away before reaching coast of England, only to return again in half an hour, when the fighters, sent up to intercept them, were landing.
Time-honoured methods of escort were at first employed. A strong fighter formation would fly a mile or so behind and above the bombers. When the Germans found that our fighters could deliver a well-timed attack on the bombers before the fighters could intervene, or when our fighters attacked from ahead or below, each move was met by a counter-move on the part of the Germans, so that, in September, fighter escorts were flying inside the bomber formation, others were below, and a series of fighters stretched upwards to 30,000 feet or more.
One Squadron Leader described his impressions of the appearance of one of these raids; he said it was like looking up the escalator at Piccadilly Circus.