“V-1 flying bomb”的意思、由来-开放百科全书

The V-1 flying bomb ({{lang-de|Vergeltungswaffe 1}} "Vengeance Weapon 1"{{efn

The V-1 was the first of the so-called "Vengeance weapons" (V-weapons or {{lang|de|Vergeltungswaffen}}) series designed for terror bombing of London. It was developed at Peenemünde Army Research Center in 1939 by the Nazi German {{lang|de|Luftwaffe}} during the Second World War. During initial development it was known by the codename "Cherry Stone". Because of its limited range, the thousands of V-1 missiles launched into England were fired from launch facilities along the French (Pas-de-Calais) and Dutch coasts. The first V-1 was launched at London on 13 June 1944,^[2] one week after (and prompted by) the successful Allied landings in Europe. At peak, more than one hundred V-1s a day were fired at south-east England, 9,521 in total, decreasing in number as sites were overrun until October 1944, when the last V-1 site in range of Britain was overrun by Allied forces. After this, the V-1s were directed at the port of Antwerp and other targets in Belgium, with 2,448 V-1s being launched. The attacks stopped only a month before the war in Europe ended, when the last launch site in the Low Countries was overrun on 29 March 1945.

The British operated an arrangement of air defences, including anti-aircraft guns and fighter aircraft, to intercept the bombs before they reached their targets as part of Operation Crossbow, while the launch sites and underground V-1 storage depots were targets of strategic bombing.^[3]

Design and development

In late 1936, while employed by the {{lang|de|Argus Motoren}} company, Fritz Gosslau began work on the further development of remote-controlled aircraft; Argus had already developed a remote-controlled surveillance aircraft, the AS 292 (military designation FZG 43).

On 9 November 1939, a proposal for a remote-controlled aircraft carrying a payload of {{convert|1000|kg|lb|abbr=on}} over a distance of {{convert |500|km|mi|abbr=on}} was forwarded to the RLM (German Air Ministry). Argus worked in cooperation with Lorentz AG and Arado Flugzeugwerke to develop the project as a private venture, and in April 1940, Gosslau presented an improved study of Project "{{lang|de|Fernfeuer}}" to the RLM, as Project P 35 "{{lang|de|Erfurt}}".

On 31 May, Rudolf Bree of the RLM commented that he saw no chance that the projectile could be deployed in combat conditions, as the proposed remote-control system was seen as a design weakness. Heinrich Koppenberg, the director of Argus, met with Ernst Udet on 6 January 1941 to try to convince him that the development should be continued, but Udet decided to cancel it.

Despite this, Gosslau was convinced that the basic idea was sound and proceeded to simplify the design. As an aircraft engine manufacturer, Argus lacked the capability to produce a fuselage for the project and Koppenberg sought the assistance of Robert Lusser, chief designer and technical director at Heinkel. On 22 January 1942, Lusser took up a position with the Fieseler aircraft company. He met Koppenberg on 27 February and was informed of Gosslau's project. Gosslau's design used two pulsejet engines; Lusser improved the design to use a single engine.

A final proposal for the project was submitted to the Technical Office of the RLM on 5 June and the project was renamed Fi 103, as Fieseler was to be the chief contractor. On 19 June, {{lang|de|Generalfeldmarschall}} Erhard Milch gave Fi 103 production high priority, and development was undertaken at the Luftwaffe's {{lang|de|Erprobungsstelle}} coastal test centre at Karlshagen, part of the Peenemünde-West facility.

By 30 August, Fieseler had completed the first fuselage, and the first flight of the Fi 103 V7 took place on 10 December 1942, when it was airdropped by a Fw 200.{{sfn|Reuter|2000|pp=56–59}}

The V-1 was named by The Reich journalist Hans Schwarz Van Berkl in June 1944 with Hitler's approval.^[4]

Description

The V-1 was designed under the codename {{lang|de|Kirschkern}} (cherry stone){{sfn|Zaloga|2005|p=6}} by Lusser and Gosslau, with a fuselage constructed mainly of welded sheet steel and wings built of plywood. The simple, Argus-built pulsejet engine pulsed 50 times per second,{{sfn|Werrell|1985|p=53}} and the characteristic buzzing sound gave rise to the colloquial names "buzz bomb" or "doodlebug" (a common name for a wide variety of flying insects). It was known briefly in Germany (on Hitler's orders) as {{lang|de|Maikäfer}} (May bug) and {{lang|de|Krähe}} (crow).{{sfn|Zaloga|2005|pp=8–9}}

Power plant

Ignition of the Argus pulsejet was accomplished using an automotive type spark plug located about {{convert|76|cm|ftin|abbr=on}} behind the intake shutters, with current supplied from a portable starting unit. Three air nozzles in the front of the pulsejet were at the same time connected to an external high-pressure air source that was used to start the engine. Acetylene gas was typically used for starting the engine, and very often a panel of wood or similar material was held across the end of the tailpipe to prevent the fuel from diffusing and escaping before ignition. The V-1 was fuelled by {{convert|625|L|USgal|abbr=off}} of 75 octane gasoline.

Once the engine had been started and the temperature had risen to the minimum operating level, the external air hose and connectors were removed and the engine's resonant design kept it firing without any further need for the electrical ignition system, which was used only to ignite the engine when starting.

The Argus As 014 (also known as a resonant jet) could operate at zero airspeed because of the nature of its intake shutters and its acoustically tuned resonant combustion chamber. However, because of the low static thrust of the pulse jet engine and the very high stall speed of the small wings, the V-1 could not take off under its own power in a practically short distance, and thus needed to be ground-launched by aircraft catapult or air-launched from a modified bomber aircraft such as a Heinkel He 111.

Beginning in January 1941, the V-1's pulsejet engine was also tested on a variety of craft, including automobiles{{sfn|Zaloga|2005|p=5}} and an experimental attack boat known as the "Tornado". The unsuccessful prototype was a version of a {{lang|de|Sprengboot}}, in which a boat loaded with explosives was steered towards a target ship and the pilot would leap out of the back at the last moment. The Tornado was assembled from surplus seaplane hulls connected in catamaran fashion with a small pilot cabin on the crossbeams. The Tornado prototype was a noisy underperformer and was abandoned in favour of more conventional piston engined craft.

The engine made its first flight aboard a Gotha Go 145 on 30 April 1941.{{sfn|Zaloga|2005|p = 5}}

Guidance system

The V-1 guidance system used a simple autopilot developed by Askania in Berlin to regulate altitude and airspeed.{{sfn|Zaloga|2005|p = 6}} The RLM at first planned to use a radio control system with the V-1 for precision attacks, but the government decided instead to use the missile against London.{{r|levine1992}} A weighted pendulum system provided fore-and-aft attitude measurement to control pitch, damped by a gyrocompass which also stabilized it. Operating power for the gyroscope platform and the flight-control actuators was provided by two large spherical compressed air tanks that also pressurized the fuel tank. These air tanks were charged to {{convert|150|atm|psi|-1|abbr=on}} before launch. With the counter determining how far the missile would fly, it was only necessary to launch the V-1 with the ramp pointing in the approximate direction, and the autopilot controlled the flight.

There was a more sophisticated interaction between yaw, roll and other sensors: a gyrocompass (set by swinging in a hangar before launch) gave feedback to control the dynamics of pitch and roll, but it was angled away from the horizontal so that controlling these degrees of freedom interacted: the gyroscope remained true on the basis of feedback received from a magnetic compass,{{citation needed|date=February 2008}} and from the fore and aft pendulum. This interaction meant that rudder control was sufficient for steering and no banking mechanism was needed. In a V-1 that landed without detonating between Tilburg and Goirle in March 1945, several rolled up issues of the German wartime propaganda magazine Signal were found inserted into the left wing's tubular steel spar, used for weight to preset the missile's static equilibrium before launching. Several of the earliest V-1s to be launched were provided with a small radio transmitter (using a triode valve marked 'S3' but equivalent to a then-current power valve, type RL 2,4T1) to check the general direction of flight related to the launching place's and the target's grid coordinates by radio bearing (navigation).

An odometer driven by a vane anemometer on the nose determined when the target area had been reached, accurately enough for area bombing. Before launch, the counter was set to a value that would reach zero upon arrival at the target in the prevailing wind conditions. As the missile flew, the airflow turned the propeller, and every 30 rotations of the propeller counted down one number on the counter. This counter triggered the arming of the warhead after about {{convert|60|km|mi|abbr=on}}.{{sfn|Werrell|1985|p=54}} When the count reached zero, two detonating bolts were fired. Two spoilers on the elevator were released, the linkage between the elevator and servo was jammed and a guillotine device cut off the control hoses to the rudder servo, setting the rudder in neutral. These actions put the V-1 into a steep dive.^[5]^[6] While this was originally intended to be a power dive, in practice the dive caused the fuel flow to cease, which stopped the engine. The sudden silence after the buzzing alerted listeners of the impending impact. The fuel problem was quickly fixed, and when the last V-1s fell, the majority hit with power.

Initially, V-1s landed within a circle {{convert|19|mi|abbr=off}} in diameter, but by the end of the war, accuracy had been improved to about 7 miles, which was comparable to the V-2 rocket.^[7]

Warhead

The warhead was 1,000 kg of Amatol-39, later the aluminised explosive Trialen was used, as used for filling other Luftwaffe 1,000 kg bombs. Trialen fillings were identified by the warhead being painted red, although the assembled missiles were painted green or grey over this.

Fuzing was by a triple fuze system. The main fuzes were an electrical impact fuze and a mechanical backup impact fuze. These were immediate action fuzes, the intention being to detonate the warhead on the first impact with the surface, rather than allowing itself to become buried first. This was a major difference from the V-2, and a reason for the high lethality of the V-1. Although they did not demolish buildings or deep structures as effectively as the air-dropped bombs, or the deep-burying V-2, their blast effects were almost all released at the surface and caused many casualties. The electrical fuze, ZLPM 76, was mounted at the front, immediately behind the compass and the air speed propeller. It connected to a central exploder tube through the warhead, containing the gaine and boosters. Two transverse fuze pockets, in typical German fashion, were placed in the upper surface of the warhead for the secondary fuzes, also connecting to this same tube.

To avoid the risk of this secret weapon being examined by the British, there was a third time delay fuze. This was too short to be any sort of booby trap, just to destroy the weapon if a soft landing had not triggered the impact fuzes. These fuzing systems were very reliable and there were almost no dud V-1s recovered.^[8]^[9]

Launch ramp

Ground-launched V-1s were typically propelled up an inclined launch ramp by an apparatus known as a {{lang|de|Dampferzeuger}} ("steam generator"), which reacted stabilized hydrogen peroxide and potassium permanganate ({{lang|de|T-Stoff}} and {{lang|de|Z-Stoff}}),{{sfn|Werrell|1985}} the same combination of chemicals used as propellants for the Messerschmitt Me 163 Komet rocket plane, and the Walter HWK 109-500 {{lang|de|Starthilfe}} RATO rocket booster unit. Ramp-launch velocity for an operational V-1 was {{convert|580|km/h|mph|abbr=on}} as it left the end of the launch ramp.

The original design for launch sites included a number of hangars or storage garages as well as preparation and command buildings, as well as the launch ramp, all of which were easily identifiable from aerial photographs resulting in bombing attacks on the sites. Launching needed a steam generator.

A light design utilising a small ({{convert|7.5|m|abbr=on|disp=or}}) preparation building, a small firing control room and the {{convert|36|m|yd|adj=on}} launch ramp which was supplied in kit form, with legs resting in concrete recesses.^[10]

Operation and effectiveness

The first complete V-1 airframe was delivered on 30 August 1942,{{sfn|Zaloga|2005|p=6}} and after the first complete As.109-014 was delivered in September,{{sfn|Zaloga|2005|p=6}} the first glide test flight was on 28 October 1942 at Peenemünde, from under a Focke-Wulf Fw 200.{{sfn|Zaloga|2005|p=5}} The first powered trial was on 10 December, launched from beneath an He 111.{{sfn|Zaloga|2005|p=6}}

The LXV Armeekorps z.b.V. formed during the last days of November 1943 in France commanded by General der Artillerie z.V. Erich Heinemann was responsible for the operational use of V-1.^[11]

The conventional launch sites could theoretically launch about 15 V-1s per day, but this rate was difficult to achieve on a consistent basis; the maximum rate achieved was 18. Overall, only about 25 per cent of the V-1s hit their targets, the majority being lost because of a combination of defensive measures, mechanical unreliability or guidance errors. With the capture or destruction of the launch facilities used to attack England, the V-1s were employed in attacks against strategic points in Belgium, primarily the port of Antwerp.

Launches against Britain were met by a variety of countermeasures, including barrage balloons and aircraft including the Hawker Tempest and Gloster Meteor. These measures were so successful that by August 1944 about 80 per cent of V-1s were being destroyed^[12] (the Meteors, although fast enough to catch the V-1s, suffered frequent cannon failures, and accounted for only 13).^[13] In all, about 1,000 V-1s were destroyed by aircraft.^[13]

The intended operational altitude was originally set at {{convert|2750|m|ft|-2|abbr=on}}. However, repeated failures of a barometric fuel-pressure regulator led to it being changed in May 1944, halving the operational height, thereby bringing V-1s into range of the Bofors guns commonly used by Allied AA units.{{sfn|Zaloga|2005|p=11}}

The trial versions of the V-1 were air-launched. Most operational V-1s were launched from static sites on land, but from July 1944 to January 1945, the {{lang|de|Luftwaffe}} launched approximately 1,176 from modified Heinkel He 111 H-22s of the {{lang|de|Luftwaffe}}'s Kampfgeschwader 3 (3rd Bomber Wing, the so-called "Blitz Wing") flying over the North Sea. Apart from the obvious motive of permitting the bombardment campaign to continue after static ground sites on the French coast were lost, air-launching gave the {{lang|de|Luftwaffe}} the opportunity to outflank the increasingly effective ground and air defences put up by the British against the missile. To minimise the associated risks (primarily radar detection), the aircrews developed a tactic called "lo-hi-lo": the He 111s would, upon leaving their airbases and crossing the coast, descend to an exceptionally low altitude. When the launch point was neared, the bombers would swiftly ascend, fire their V-1s, and then rapidly descend again to the previous "wave-top" level for the return flight. Research after the war estimated a 40 per cent failure rate of air-launched V-1s, and the He 111s used in this role were vulnerable to night-fighter attack, as the launch lit up the area around the aircraft for several seconds. The combat potential of air-launched V-1s dwindled as 1944 progressed at about the same rate as that of the ground-launched missiles, as the British gradually took the measure of the weapon and developed increasingly effective defence tactics.

Experimental and long-range variants

Late in the war, several air-launched piloted V-1s, known as {{lang|de|Reichenbergs}}, were built, but these were never used in combat. Hanna Reitsch made some flights in the modified V-1 Fieseler {{lang|de|Reichenberg}} when she was asked to find out why test pilots were unable to land it and had died as a result. She discovered, after simulated landing attempts at high altitude where there was air space to recover, that the craft had an extremely high stall speed and the previous pilots with little high-speed experience had attempted their approaches much too slowly. Her recommendation of much higher landing speeds was then introduced in training new {{lang|de|Reichenberg}} volunteer pilots. The {{lang|de|Reichenberg}}s were air-launched rather than fired from a catapult ramp as erroneously portrayed in the film Operation Crossbow.{{citation needed|date=June 2017}}

There were plans, not put into practice, to use the Arado Ar 234 jet bomber to launch V-1s either by towing them aloft or by launching them from a "piggy back" position (in the manner of the {{lang|de|Mistel}}, but in reverse) atop the aircraft. In the latter configuration, a pilot-controlled, hydraulically operated dorsal trapeze mechanism would elevate the missile on the trapeze's launch cradle some eight feet clear of the 234's upper fuselage. This was necessary to avoid damaging the mother craft's fuselage and tail surfaces when the pulsejet ignited, as well as to ensure a "clean" airflow for the Argus motor's intake. A somewhat less ambitious project undertaken was the adaptation of the missile as a "flying fuel tank" {{lang|de|(Deichselschlepp)}} for the Messerschmitt Me 262 jet fighter, which was initially test-towed behind an He 177A {{lang|de|Greif}} bomber. The pulsejet, internal systems and warhead of the missile were removed, leaving only the wings and basic fuselage, now containing a single large fuel tank. A small cylindrical module, similar in shape to a finless dart, was placed atop the vertical stabilizer at the rear of the tank, acting as a centre of gravity balance and attachment point for a variety of equipment sets. A rigid tow-bar with a pitch pivot at the forward end connected the flying tank to the Me 262. The operational procedure for this unusual configuration saw the tank resting on a wheeled trolley for take-off. The trolley was dropped once the combination was airborne, and explosive bolts separated the towbar from the fighter upon exhaustion of the tank's fuel supply. A number of test flights were conducted in 1944 with this set-up, but inflight "porpoising" of the tank, with the instability transferred to the fighter, meant the system was too unreliable to be used. An identical utilisation of the V-1 flying tank for the Ar 234 bomber was also investigated, with the same conclusions reached. Some of the "flying fuel tanks" used in trials utilised a cumbersome fixed and spatted undercarriage arrangement, which (along with being pointless) merely increased the drag and stability problems already inherent in the design.{{citation needed|date=June 2017}}

One variant of the basic Fi 103 design did see operational use. The progressive loss of French launch sites as 1944 proceeded and the area of territory under German control shrank meant that soon the V-1 would lack the range to hit targets in England. Air-launching was one alternative utilised, but the most obvious solution was to extend the missile's range. Thus the F-1 version developed. The weapon's fuel tank was increased in size, with a corresponding reduction in the capacity of the warhead. Additionally, the nose-cones and wings of the F-1 models were made of wood, affording a considerable weight saving. With these modifications, the V-1 could be fired at London and nearby urban centres from prospective ground sites in the Netherlands. Frantic efforts were made to construct a sufficient number of F-1s in order to allow a large-scale bombardment campaign to coincide with the Ardennes Offensive, but numerous factors (bombing of the factories producing the missiles, shortages of steel and rail transport, the chaotic tactical situation Germany was facing at this point in the war, etc.) delayed the delivery of these long-range V-1s until February/March 1945. Beginning on 2 March 1945, slightly more than three weeks before the V-1 campaign finally ended, several hundred F-1s were launched at Britain from Dutch sites under Operation "Zeppelin". Frustrated by increasing Allied dominance in the air, Germany also employed V1s to attack the RAF's forward airfields, such as Volkel, in the Netherlands.^[14]

There was also a turbojet-propelled upgraded variant proposed,^[15] meant to use the Porsche 109-005 low-cost turbojet engine^[16] of some 500 kgf (1,100 lbf) thrust.

Almost 30,000 V-1s were made; by March 1944, they were each produced in 350 hours (including 120 for the autopilot), at a cost of just 4 per cent of a V-2,{{sfn|Zaloga|2005|p=11}} which delivered a comparable payload. Approximately 10,000 were fired at England; 2,419 reached London, killing about 6,184 people and injuring 17,981.^[17] The greatest density of hits were received by Croydon, on the south-east fringe of London. Antwerp, Belgium was hit by 2,448 V-1s from October 1944 to March 1945.^[18]^[19]

Intelligence reports

The codename "{{lang|de|Flakzielgerät}} 76"—"Flak target apparatus" helped to hide the nature of the device, and some time passed before references to FZG 76 were linked to the V-83 pilotless aircraft (an experimental V-1) that had crashed on Bornholm in the Baltic and to reports from agents of a flying bomb capable of being used against London. Importantly, the Polish Home Army intelligence contributed information on V-1 construction and a place of development (Peenemünde). Initially, British experts were sceptical of the V-1 because they had considered only solid fuel rockets, which could not attain the stated range of {{convert|1000|kg|lb|abbr=on}}: {{convert|130|mi|abbr=off}}. However, they later considered other types of engine, and by the time German scientists had achieved the needed accuracy to deploy the V-1 as a weapon, British intelligence had a very accurate assessment of it.^[20]

Countermeasures in England

Anti-aircraft guns

The British defence against the German long-range weapons was Operation Crossbow. Anti-aircraft guns of the Royal Artillery and RAF Regiment redeployed in several movements: first in mid-June 1944 from positions on the North Downs to the south coast of England, then a cordon closing the Thames Estuary to attacks from the east. In September 1944, a new linear defence line was formed on the coast of East Anglia, and finally in December there was a further layout along the Lincolnshire–Yorkshire coast. The deployments were prompted by changes to the approach tracks of the V-1 as launch sites were overrun by the Allies' advance.

On the first night of sustained bombardment, the anti-aircraft crews around Croydon were jubilant – suddenly they were downing unprecedented numbers of German bombers; most of their targets burst into flames and fell when their engines cut out. There was great disappointment when the truth was announced. Anti-aircraft gunners soon found that such small fast-moving targets were, in fact, very difficult to hit. The cruising altitude of the V-1, between {{convert|600|to|900|m|ft|abbr=on}}, was just above the effective range of light anti-aircraft guns, and just below the optimum engagement height of heavier guns.

The altitude and speed were more than the rate of traverse of the standard British QF 3.7-inch mobile gun could cope with. The static version of the QF 3.7-inch, designed for use on a permanent, concrete platform, had a faster traverse. The cost and delay of installing new permanent platforms for the guns was fortunately found to be unnecessary - a temporary platform built devised by the REME and made from railway sleepers and rails was found to be adequate for the static guns, making them considerably easier to re-deploy as the V-1 threat changed.^[21]{{efn|This was known as a Pyle platform, after the head of Anti-Aircraft Command, General Frederick Alfred Pile}}

The development of the proximity fuze and of centimetric, 3 gigahertz frequency gun-laying radars based on the cavity magnetron helped to counter the V-1's high speed and small size. In 1944, Bell Labs started delivery of an anti-aircraft predictor fire-control system based on an analogue computer, just in time for the Allied invasion of Europe.

These electronic aids arrived in quantity from June 1944, just as the guns reached their firing positions on the coast. Seventeen per cent of all flying bombs entering the coastal "gun belt" were destroyed by guns in their first week on the coast. This rose to 60 per cent by 23 August and 74 per cent in the last week of the month, when on one day 82 per cent were shot down. The rate improved from one V-1 destroyed for every 2,500 shells fired initially, to one for every 100. This still did not end the threat, and V-1 attacks continued until all launch sites were captured by ground forces.

Barrage balloons

Eventually some 2,000 barrage balloons were deployed, in the hope that V-1s would be destroyed when they struck the balloons' tethering cables. The leading edges of the V-1's wings were fitted with cable cutters, and fewer than 300 V-1s are known to have been brought down by barrage balloons.^[22]

Interceptors

The Defence Committee expressed some doubt as to the ability of the Royal Observer Corps to adequately deal with the new threat, but the ROC's Commandant Air Commodore Finlay Crerar assured the committee that the ROC could again rise to the occasion and prove its alertness and flexibility. He oversaw plans for handling the new threat, codenamed by the RAF and ROC as "Operation Totter".

Observers at the coast post of Dymchurch identified the very first of these weapons and within seconds of their report the anti-aircraft defences were in action. This new weapon gave the ROC much additional work both at posts and operations rooms. Eventually RAF controllers actually took their radio equipment to the two closest ROC operations rooms at Horsham and Maidstone, and vectored fighters direct from the ROC's plotting tables. The critics who had said that the Corps would be unable to handle the fast-flying jet aircraft were answered when these aircraft on their first operation were actually controlled entirely by using ROC information both on the coast and at inland.

The average speed of V-1s was {{convert|550|km/h|abbr=on}} and their average altitude was {{convert|1000|m|abbr=on}} to {{convert |1200|m|abbr=on}}. Fighter aircraft required excellent low altitude performance to intercept them and enough firepower to ensure that they were destroyed in the air rather than crashing to earth and detonating. Most aircraft were too slow to catch a V-1 unless they had a height advantage, allowing them to gain speed by diving on their target.

When V-1 attacks began in mid-June 1944, the only aircraft with the low-altitude speed to be effective against it was the Hawker Tempest. Fewer than 30 Tempests were available. They were assigned to No. 150 Wing RAF. Early attempts to intercept and destroy V-1s often failed, but improved techniques soon emerged. These included using the airflow over an interceptor's wing to raise one wing of the V-1, by sliding the wingtip to within {{convert|6|in|cm|abbr=on}} of the lower surface of the V-1's wing. If properly executed, this manoeuvre would tip the V-1's wing up, overriding the gyro and sending the V-1 into an out-of-control dive. At least sixteen V-1s were destroyed this way (the first by a P-51 piloted by Major R. E. Turner of 356th Fighter Squadron on 18 June).^[23] It could be seen that the aerodynamic flip method was actually effective when V-1s could be seen over southern parts of the Netherlands headed due eastwards at low altitude, the engine quenched. In early 1945 such a missile soared below clouds over Tilburg to gently alight eastwards of the city in open fields.

The Tempest fleet was built up to over 100 aircraft by September. Specially modified P-47M Thunderbolts (half their fuel tanks, half their 0.5in {12.7 mm} machine guns, boosted engines (2800 hp), all external fittings, and all their armour plate removed) were also pressed into service against the V-1s. In addition, North American P-51 Mustangs and Griffon-engined Supermarine Spitfire Mk XIVs were tuned to make them fast enough, and during the short summer nights the Tempests shared defensive duty with de Havilland Mosquitos. There was no need for airborne radar; at night the V-1's engine could be heard from {{convert|10|mi|km|abbr=on}} away or more, and the exhaust plume was visible from a long distance. Wing Commander Roland Beamont had the 20 mm cannon on his Tempest adjusted to converge at {{convert|300|yd|m|abbr=on}} ahead. This was so successful that all other aircraft in 150 Wing were thus modified.

The anti-V-1 sorties by fighters were known as "Diver patrols" (after "Diver", the codename used by the Royal Observer Corps for V-1 sightings). Attacking a V-1 was dangerous: machine guns had little effect on the V-1's sheet steel structure, and if a cannon shell detonated the warhead, the explosion could destroy the attacker.

In daylight, V-1 chases were chaotic and often unsuccessful until a special defence zone was declared between London and the coast, in which only the fastest fighters were permitted. The first interception of a V-1 was by F/L J. G. Musgrave with a No. 605 Squadron RAF Mosquito night fighter on the night of 14/15 June 1944. As daylight grew stronger after the night attack, a Spitfire was seen to follow closely behind a V-1 over Chislehurst and Lewisham. Between June and 5 September 1944, a handful of 150 Wing Tempests shot down 638 flying bombs,^[24] with No. 3 Squadron RAF alone claiming 305. One Tempest pilot, Squadron Leader Joseph Berry (RAF officer) (501 Squadron), shot down 59 V-1s, the Belgian ace Squadron Leader Remy Van Lierde (164 Squadron) destroyed 44 (with a further nine shared) and W/C Roland Beamont (see above) destroyed 31.

The next most successful interceptors were the Mosquito (623 victories),{{sfn|Sharp|Bowyer|1995|p=179}} Spitfire XIV (303),^[25] and Mustang (232). All other types combined added 158. Even though it was not fully operational, the jet-powered Gloster Meteor was rushed into service with No. 616 Squadron RAF to fight the V-1s. It had ample speed but its cannons were prone to jamming, and it shot down only 13 V-1s.{{sfn|Cooper|1997|p=8}}

In late 1944 a radar-equipped Vickers Wellington bomber was modified for use by the RAF's Fighter Interception Unit as an Airborne Early Warning and Control aircraft.{{sfn|Jackson|2007|p=217}} Flying at an altitude of {{convert |4000|ft|m}} over the North Sea, it directed Mosquito fighters charged with intercepting He 111s from Dutch airbases that sought to launch V-1s from the air.

Disposal

The first bomb disposal officer to defuse an unexploded V-1 was John Pilkington Hudson in 1944.{{sfn|Self|2011}}

Deception

To adjust and correct settings in the V-1 guidance system, the Germans needed to know where the V-1s were impacting. Therefore, German intelligence was requested to obtain this impact data from their agents in Britain. However, all German agents in Britain had been turned, and were acting as double agents under British control.

On 16 June 1944, British double agent Garbo (Juan Pujol) was requested by his German controllers to give information on the sites and times of V-1 impacts, with similar requests made to the other German agents in Britain, Brutus (Roman Czerniawski) and Tate (Wulf Schmidt). If given this data, the Germans would be able to adjust their aim and correct any shortfall. However, there was no plausible reason why the double agents could not supply accurate data; the impacts would be common knowledge amongst Londoners and very likely reported in the press, which the Germans had ready access to through the neutral nations. In addition, as John Cecil Masterman, chairman of the Twenty Committee, commented, "If, for example, St Paul's Cathedral were hit, it was useless and harmful to report that the bomb had descended upon a cinema in Islington, since the truth would inevitably get through to Germany ..."{{sfn|Masterman|1972|pp=252–53}}

While the British decided how to react, Pujol played for time. On 18 June it was decided that the double agents would report the damage caused by V-1s fairly accurately and minimise the effect they had on civilian morale. It was also decided that Pujol should avoid giving the times of impacts, and should mostly report on those which occurred in the north west of London, to give the impression to the Germans that they were overshooting the target area.{{sfn|Crowdy|2008|pp=273–74}}

While Pujol downplayed the extent of V-1 damage, trouble came from Ostro, an {{lang|de|Abwehr}} agent in Lisbon who pretended to have agents reporting from London. He told the Germans that London had been devastated and had been mostly evacuated as a result of enormous casualties. The Germans could not perform aerial reconnaissance of London, and believed his damage reports in preference to Pujol's. They thought that the Allies would make every effort to destroy the V-1 launch sites in France. They also accepted Ostro{{'}}s impact reports. Due to Ultra, however, the Allies read his messages and adjusted for them.{{sfn|Masterman|1972|p=254}}

A certain number of the V-1s fired had been fitted with radio transmitters, which had clearly demonstrated a tendency for the V-1 to fall short. {{lang|de|Oberst}} Max Wachtel, commander of Flak Regiment 155 (W), which was responsible for the V-1 offensive, compared the data gathered by the transmitters with the reports obtained through the double agents. He concluded, when faced with the discrepancy between the two sets of data, that there must be a fault with the radio transmitters, as he had been assured that the agents were completely reliable. It was later calculated that if Wachtel had disregarded the agents' reports and relied on the radio data, he would have made the correct adjustments to the V-1's guidance, and casualties might have increased by 50 per cent or more.{{sfn|Jones|1978|p=422}}{{sfn|Crowdy|2008|p=280}}

The policy of diverting V-1 impacts away from central London was initially controversial. The War Cabinet refused to authorise a measure that would increase casualties in any area, even if it reduced casualties elsewhere by greater amounts. It was thought that Churchill would reverse this decision later (he was then away at a conference); but the delay in starting the reports to Germans might be fatal to the deception. So Sir Findlater Stewart of Home Defence Executive took responsibility for starting the deception programme immediately, and his action was approved by Churchill when he returned.{{sfn|Montagu|1978|pp=151–58}}

End of the V-1 attacks against England

By September 1944, the V-1 threat to England was temporarily halted when the launch sites on the French coast were overrun by the advancing Allied armies. 4,261 V-1s had been destroyed by fighters, anti-aircraft fire and barrage balloons. The last enemy action of any kind on British soil occurred on 29 March 1945, when a V-1 struck Datchworth in Hertfordshire.

Assessment

Unlike the V-2, the V-1 was a cost-effective weapon for the Germans as it forced the Allies to spend heavily on defensive measures and divert bombers from other targets. More than 25 per cent of Combined Bomber Offensive's bombs in July and August 1944 were used against V-weapon sites, often ineffectively.^[26] In early December 1944, American General Clayton Bissell wrote a paper that argued strongly in favour of the V-1 when compared with conventional bombers.{{sfn|Irons|2003|p=199}}

The statistics of this report, however, have been the subject of some dispute. The V-1 missiles launched from bombers were often prone to exploding prematurely, occasionally resulting in the loss of the aircraft to which they were attached. The Luftwaffe lost 77 aircraft in 1,200 of these sorties.^[27]

Wright Field technical personnel reverse-engineered the V-1 from the remains of one that had failed to detonate in Britain. The result was the creation of the JB-2 Loon.

General Hap Arnold of the United States Army Air Forces was concerned that this weapon could be built of steel and wood, in 2000 man hours and approximate cost of US$600 (in 1943).^[28] To put this figure in perspective, a Boeing B-29 Superfortress cost ~1000x more, and still ~100x more when taking into account its 10x higher payload (20,000 lb Vs 850 kg for V1) -- payload, which cost has to be added (while it is included in V1 cost) --, with the additional drawback of requiring (and putting in danger) 11 flying crew members.

Belgian attacks

The attacks on Antwerp and Brussels began in October 1944, with the last V-1 launched against Antwerp on 30 March 1945.^[30]{{rp|31}}

Antwerp was recognised by both the German and Allied high command as a very important port, essential to the further progression of Allied armies into Germany.^[30] The shorter range improved the accuracy of the V-1 which was six miles deviation per hundred miles of flight, the flight level was also reduced to around 3,000 ft.^[29]{{rp|9}}

Countermeasures at Antwerp

Both British (80 AA Brigade) and US Army anti-aircraft batteries (30th AAA Group) were sent to Antwerp together with a searchlight regiment. The zone of command under the 21st Army Group was called "Antwerp-X" and given the object of protecting an area with a radius of 7,000 yards covering the city and dock area.^[29]{{rp|34}} Initially attacks came from the south-east, accordingly a screen of observers and searchlights was deployed along the attack azimuth, behind which were three rows of batteries with additional searchlights.^[29]{{rp|36}}

US units deployed SCR-584 radar units controlling four 90mm guns per battery using an M9 director to electrically control the battery guns.^[29]{{rp|40}} Backup for the American guns was automatic 40mm batteries, which were not effective against V-1s.

British gun batteries were each equipped with eight QF 3.7-inch AA gun and two radar units, preferably the US SCR-584 with M9 director as it was more accurate than the British system.^[29]{{rp|45}} Backup for the British guns was also automatic 40mm batteries.

The radar was effective from 28,000 yards, the M9 director predicted the target location position based on course, height and speed which combined with the gun, shell and fuse characteristics predicted an impact position, adjusted each gun and fired the shell.^[29]{{rp|51}}

In November attacks began from the north-east and additional batteries were deployed along the new azimuths, including the 184th AAA Battalion (United States) brought from Paris. Additional radar units and observers were deployed up to 40 miles from Antwerp to give early warning of V-1 bombs approaching.^[29]{{rp|53}} The introduction of the VT fuse in January 1945 improved the effectiveness of the guns and reduced ammunition consumption.^[29]{{rp|68}}

From October 1944 to March 1945 4,883 V-1's were detected. Of these, only 4.5% fell into the designated protected area.^[29]{{rp|54}} The effectiveness of the anti aircraft defence meant that only 211 got through the defences, however those that fell within the area caused damage and loss of life.

Japanese developments

In 1943, an Argus pulsejet engine was shipped to Japan by German submarine. The Aeronautical Institute of Tokyo Imperial University and the Kawanishi Aircraft Company conducted a joint study of the feasibility of mounting a similar engine on a piloted plane. The resulting design was named {{transl|ja|Baika}} ("plum blossom") but bore no more than a superficial resemblance to the Fi 103. {{transl|ja|Baika}} never left the design stage but technical drawings and notes suggest that several versions were considered: an air-launched version with the engine under the fuselage, a ground-launched version that could take off without a ramp and a submarine launched version with the engine moved forwards.

Post-war

After the war, the armed forces of France, the Soviet Union and the United States experimented with the V-1.

France

After reverse-engineering captured V-1s in 1946, the French began producing copies for use as target drones, starting in 1951. These were called the ARSAERO CT 10 and were smaller than the V-1. The CT 10 could be ground-launched using solid rocket boosters or air-launched from a LeO 45 bomber. More than 400 were produced, some of which were exported to the UK, Sweden, and Italy.^[30]

Soviet Union

The Soviet Union captured V-1s when they overran the Blizna test range in Poland, as well as from the Mittelwerk.^[31] The 10Kh was their copy of the V-1, later called Izdeliye 10.^[32] Initial tests began in March 1945 at a test range in Tashkent,^[32] with further launches from ground sites and from aircraft of improved versions continuing into the late 1940s. The inaccuracy of the guidance system when compared with new methods such as beam-riding and TV guidance saw development end in the early 1950s.

The Soviets also worked on a piloted attack aircraft based on the Argus pulsejet engine of the V-1, which began as a German project, the Junkers EF 126 {{lang|de|Lilli}},^[33] in the latter stages of the war. The Soviet development of the {{lang|de|Lilli}} ended in 1946 after a crash that killed the test pilot.^[32]

United States

The United States reverse-engineered the V-1 in 1944 from salvaged parts recovered in England during June. By 8 September, the first of thirteen complete prototype Republic-Ford JB-2 Loons, was assembled at Republic Aviation. The United States JB-2 was different from the German V-1 in only the smallest of dimensions. The wing span was only {{convert|2.5|in|cm|abbr=on}} wider and the length was extended less than {{convert|2|ft|m|abbr=on}}. The difference gave the JB-2 {{convert|60.7|sqft|m2}} of wing area versus {{convert |55|sqft|m2}} for the V-1.{{sfn|Mindling|Bolton|2009}}{{Rp|needed=yes|date=February 2012}}

A navalized version, designated KGW-1, was developed to be launched from LSTs as well as escort carriers (CVEs) and long-range 4-engine reconnaissance aircraft. Waterproof carriers for the KGW-1 were developed for launches of the missile from surfaced submarines. Both the USAAF JB-2 and Navy KGW-1 were put into production and were planned to be used in the Allied invasion of Japan (Operation Downfall). However, the surrender of Japan obviated the need for its use.{{sfn|Mindling|Bolton|2009}}{{Rp|needed=yes|date=February 2012}} After the end of the war, the JB-2/KGW-1 played a significant role in the development of more advanced surface-to-surface tactical missile systems such as the MGM-1 Matador and later MGM-13 Mace.

Operators

Surviving examples