A Zeppelin over London by Ivan Berryman.
From 1915 to 1917, there existed a very real threat of a bombing campaign on mainland Britain as the giant German airships drifted silently and menacingly across the English Channel and the North Sea to deliver their deadly cargo on the towns and cities of the east coast. Countermeasures were soon put into action as powerful searchlights picked out the Zeppelins for the anti-aircraft batteries and RFC pilots to pour their unrelenting fire into the raiders, sometimes with little effect, sometimes with catastrophic results. Here, 2nd Lieutenant Brandons BE.2 climbs for position, its exhaust pipes aglow in the dark, whilst flak bursts all around the massive bulk of the L.33 as she passes over the east end of London on the night of 23 / 24th September 1916.
In the second half of 1915 the RFC gradually began making a positive contribution to British aerial defence. When it took over from the RNAS officially in December it had ten permanent night-fighter airfields, each with two aircraft at readiness, with many more being prepared. Virtually all the RFC combat aircraft were by now of the B.E.2c type, the mass-produced general-purpose machine designed as standard RFC equipment by the Royal Aircraft Factory at Farnborough. Its dominant feature was strong inherent stability, and while this was an often fatal handicap on the Western Front in daylight, in one-sided combat against the agile Fokker monoplane, it was a major advantage in night missions against airships. On the other hand, the B.E. had only a slight performance advantage over the 1915 Zeppelins. The quoted maximum speed on the level was 72 mph and the ceiling 10,000 feet, but a B.E. significantly lower than an airship was unable to make an interception; it could overhaul the airship or climb to the same level, but could not do both simultaneously. Indeed on the night of 13 October 1915 Lieutenant J.C. Slessor – who much later was to become Chief of the Air Staff – found the greatest difficulty in maintaining control of his B.E. as it staggered along at full throttle at its ceiling in a vain attempt to reach L15, clearly visible high over a brightly lit London. Eventually he had to give up the chase, and with tanks almost dry, he glided back to Sutton’s Farm, near Hornchurch, easily found because of its distinctive coloured petrol flares. As he neared it, the airfield was swiftly becoming covered in a thin layer of dense white mist. Left alone he might have pulled off a good landing, but as he descended into the mist the searchlight crew at the side of the airfield decided to help. Aiming their beam at him he was blinded, and the mist suddenly became brilliantly white. Slessor was lucky to finish with a B.E. that was, after some discussion, judged repairable.
As the first night fighter in history, the B.E.2c might deserve careful study, but in fact it was merely a lash-up – as were most combat aircraft of the early part of the First World War. The B.E. had been designed when the War Office was adamant that the only possible use for aeroplanes was reconnaissance. Later many hundreds of all kinds of B.E. were used as bombers, being flown solo from the rear cockpit. They were hacked down in droves by the deadly Fokkers, being low, slow, incapable of rapid manoeuvre and, usually, unarmed (because they could not carry bombs and also a gun). As a night fighter, however, they were at least less likely to be shot down. In this role they were again flown solo, and a drum-fed Lewis was mounted on the centre of the upper wing, firing at an angle that cleared the propeller disc. Instruments were marked in luminous paint, and some had an internal lamp. Their stability made them steady gun platforms, and probably safer than any other aircraft in the still extremely chancy business of night flying; but their performance was marginal in the One wonders why nothing was done to build up a strong force of faster, higher-climbing night fighters. One of the best aircraft would have been the little Bristol Scout, which as early as February 1914 reached the then excellent speed of 95 mph. Even when carrying a machine-gun the Scout C of 1915 could comfortably exceed 90 mph, and climb to 15,500 feet. Though used by many RFC and RNAS units, the Scout was issued in ones and twos, and total production was trivial (for example, 87 C models for the RFC and 74 for the RNAS). Very easy to fly, highly manoeuvrable, and capable of climbing to 10,000 feet in twenty minutes to intercept a Zeppelin, the little Scout seemed in 1915 to be the ideal night fighter, but the number in use at any time could be counted on the fingers. Indeed, it seemed to be a perverse law of the British procurement machine that, while the excellent Bristol Scout and M.1C monoplane were almost ignored, along with several other potentially outstanding fighters, the almost unmanoeuvrable B.E.2 family were built in ever-greater quantities by more and more factories.
One of the weapons carried by the Bristol Scout was the Ranken dart, a development of the hooked petrol bomb. Devised by RN Engineer Lieutenant Francis Ranken, it comprised a slim dart with an explosive head and four sprung vanes at the rear. Carried in metal boxes of 24, the darts were released three at a time. The idea was that the head would pierce the fabric of the airship, the fuse would be detonated and the charge would explode before the tail vanes had torn through. Even if no fire was caused, the rent was thought certain to cause gross loss of gas. The little Scout often carried two boxes of 24. Another weapon was the Le Prieur rocket, originally designed for destroying observation balloons. This was the simplest possible rocket, with a hard pointed nose, launched from a tube carried on the interplane struts, giving an upward inclination at launch. Many fighters carried up to eight or even twelve rockets, which were usually salvoed all at once. Incendiary ammunition, and later explosive Pomeroy bullets, were predominant in the 97-round drums made up for the Lewis guns of fighters on night Zeppelin patrol. In the experimental shops of Royal Ordnance Factories, Vickers, and other works were to be found several purpose-designed guns for destroying the raiding monsters. Certainly the few pilots who did succeed in reaching a Zeppelin were greatly disheartened to pump drum after drum of 0.303in ammunition (incendiary included) right through the vast silvery envelope and see no evident effect. In two cases there was an effect, the airship later making a forced landing; but this was not known to the fighter pilot.
During 1915 a spate of more or less bizarre aircraft were designed expressly to beat the Zeppelin raiders. One of the first was the A.D. Scout, designed by Haris Booth at the Admiralty Air Department. This lofty but quite unsuitable aeroplane had a nacelle about ten feet off the ground attached to the upper pair of wings, and carrying the Davis recoilless gun. The Davis came in several versions, the most common firing a ½ or 2-pounder shell, and had its development been carried to completion it would probably have been a formidable weapon. The Davis was also specified for the Blackburn Triplane, which resembled a slightly less grotesque form of the A.D. Scout, and also for the P.V.2 designed at the RNAS Experimental Depot at Port Victoria, on the Isle of Grain, in the Thames estuary. The P.V.2 was a fine-looking seaplane which actually flew (in June 1916). So did the Robey-Peters three-seat gun carrier, a pugnacious biplane carrying Davis gunners in streamlined nacelles on both the left and right upper wings.
Two of the aircraft featured in the author’s small sketches (overleaf) are the Royal Aircraft Factory N.E.1 and Vickers F.B.25. These undistinguished aircraft were both fitted with a powerful searchlight in the nose. There seems to be no evidence that either aircraft was used for any serious experiments to see whether or not a searchlight might be of value in finding hostile aircraft at night, but it is at once obvious that switching on an airborne searchlight instantly betrays the presence and location of one’s own aircraft. Like so many weapons and counter-weapons, an airborne searchlight might increase a night fighter’s vunerability, rather than its lethality. At the same time, when one considers that visible light is merely electromagnetic radiation, just like the emissions from radar, one is left wondering why all the later effort was put into radar, and almost none into airborne searchlights. The only serious trials with later airborne searchlights were, in the author’s opinion, ridiculous; for some reason the device was called a Turbinlite, as described later.
Returning to the First World War, all these supposed anti-Zeppelin night fighters pale into insignificance beside the weird creations of Noel Pemberton-Billing. ‘PB’ was a colourful character, to put it mildly. When the First World War broke out he asked the Admiralty what sort of aircraft it wanted, went back to his factory, drew outlines on the walls, and did not let anybody go home until the prototype was completed seven days later. (It was a surprisingly good machine.) By 1916 PB had gained a commission in the RNAS, resigned to become MP for East Hertfordshire, and designed several further combat machines. The latest, completed in the first four weeks of 1916, was the P.B. 29E, a vast but fragile-looking quadruplane. In PB’s book Air War: how to wage it appeared an explanation: ‘A fleet of defending aeroplanes is necessary. Each must be so armed as to be capable of destroying an airship at a range equal to the range of its own searchlight, which must be not less than one mile. It must have at least a speed of 80 mph in order to overtake airships. It must be able to fly as slowly as 35 mph to economise fuel and to render accurate gunfire and night landing possible . . .’ Other requirements were 12 hours’ endurance, silenced engines, dual pilots (because of the long missions) and ability to reach 10,000 feet in 20 minutes. Fast climb was not expected to be needed, because, to quote PB, the idea was ‘to stand still in the air in a 28 mph breeze and lie in wait for Zeppelins’. Commander Seddon flew the 29E at Chingford in February 1916 but it later crashed. This did not discourage PB from later building the even more extraordinary P.B.31E. Planned in mid-March 1916, this was again built for the Admiralty, and was a veritable sky battleship. The main armament was a 1½-pdr Davis on the upper floor of the crew compartment, level with the uppermost of the four wings. In the bow cockpit was a pair of Lewis guns, and on the extreme nose was mounted a powerful searchlight carried on gimbals and trained by the bow gunner. The generating plant ‘sounded like a T-T race’. Clifford Prodger got the contraption into the air in February 1917, but it was doomed by the feeble 100 hp of its Salmson engines. By this time PB had sold the works to his co-directors and it was renamed Supermarine Aviation; so the 31E was an early ancestor of the Spitfire!
Another specialized anti-Zeppelin weapon was the Crayford rocket gun, developed by the Vickers works at that Kentish town. This fearsome weapon was tested on the range but may never have flown. The first designated carrier was the Zeppelin Scout built by Parnall Aircraft in 1916. A large single-seat biplane, the ZS had the monster gun fixed on the right side at an elevation of 45°. In contrast, Vickers’ own F.B. 25, flown in the first weeks of 1917, entrusted the rocket gun to a gunner in a separate cockpit just ahead of the pilot and on the right side, with a manually aimed mounting. The corresponding machine from the Royal Aircraft Factory was the N.E.1 (Night Experimental), a slender biplane with a central pusher nacelle. In the bow was the pilot, with his own Lewis and a searchlight. Behind was the gunner, with the Vickers rocket gun and a second searchlight.
While these and other strange anti-Zeppelin night fighters swiftly took shape in British factories, established machines were used in new ways. RNAS fighters, in particular, were used in experiments aimed at increasing the proportion of each Zeppelin’s mission in which it could be attacked. Sopwith 1½-Strutters and Pups, and later Camels, with wheel or skid landing gear, were towed far out across the North Sea on lighters, some of them to alight again after their patrol on rubber-fabric inflatable bags. A few Sopwith Babies, Camel 2F.1s and Pups were equipped as night fighters operating from the world’s first aircraft carriers, HMS Furious and seaplane carriers Engadine and Vindex, with the usual fixed Vickers gun replaced by a tripod-mounted Lewis and with floats or flotation bags. Perhaps most remarkable of all, one of Vindex’s Bristol Scouts was successfully borne aloft and released from above the upper wing of a Porte Baby flying boat, on 17 May 1916. The aim was to carry the little fighter to about 6,000 feet altitude some one hundred miles beyond the furthest point it could reach in unaided anti-Zeppelin patrol; but, like all schemes which relied on a chance meeting with an airship, it was of little practical use.
Moreover, whereas the earliest German military and naval airships had had no defensive armament, their larger and more powerful successors bristled with many guns. On 30 May 1916 the first of the so-called ‘Super Zeppelin’ R-class, ship L30, entered service with the Naval Airship Division. Powered by six 360hp Maybach engines, she had a displacement of no less than 1,949,600 ft3, and was fractionally under 650 feet long. Her lifting power was such that, while the 1914 ships could barely climb above 10,000 feet with a tonne (2,205 lb) of bombs, the R-class could load five tonnes of bombs (over 11,000 lb), plus all-round defensive armament, and still climb to 20,000 feet. L30 entered service, commanded by Oberleutnant Baron von Buttlar, with a total of ten Parabellum machine-guns; soon at least one of these was replaced by a Becker 20 mm cannon. As an interesting aside, whereas the boundary layer of sluggish air at the bows of an airship might be only an inch thick, 500 feet further aft it would have grown to at least three feet. A man could crouch on top of the ship and not be swept overboard; only his hair would be ruffled by the slipstream. For this reason, defensive gunners were usually placed near the stern, where they could man their gun(s) partly outside the envelope in a gentle breeze and with a clear field of fire.
Thus, in the middle war years the advantage tended to swing in favour of the attacking airships. It was increasingly evident that the only answer to these attacks lay in improved early warning, improved tracking of the raiders, improved communications, and more and better fighters. By the end of 1916 there were thirty night-fighter airfields at instant readiness from Kent to Scotland, housing 2,000 RFC or RNAS Home Defence personnel, backed up by a further 15,000 manning searchlights or anti-aircraft gun posts. Though the airships seemed to lead a charmed life, almost every one of them encountered close AA fire over Britain and, on an increasing number of occasions, a successful interception by a night fighter. On one occasion, in April 1916, a veteran Zeppelin and crew – L15, the one that got away from Slessor – was hit by AA fire at Purfleet and finally succumbed to darts dropped by a B.E.2c; but she went down gently, and finally broke up more than two hours later off the Essex coast. What the British public wished to see was a raider going down in flames.