V-1 (flying bomb)

V-1 flying bomb Fieseler Fi 103 Flakzielgerät 76 (FZG-76)
V-1 flying bomb
Type	Guided missile
Place of origin	Nazi Germany
Service history
In service	1944-1945
Used by	Luftwaffe
Wars	World War II
Production history
Manufacturer	Fieseler
Unit cost	5,090 RM[1]
Specifications
Weight	2,150 kg (4,750 lb)
Length	8.32 meters (27 feet 3¾ inches)
Width	5.37 meters (17 feet 6 inches)
Height	1.42 meters (4 feet 8 inches)
Warhead	Amatol-39
Warhead weight	850 kg (1,870 lb)
Engine	Argus As 109-014 pulse jet engine
Operational range	250 km (150 miles)[2]
Speed	640 km/h (400 mph) flying between 600 to 900 m (2,000 to 3,000 ft)
Guidance system	gyrocompass based autopilot

The Fieseler Fi 103, better known as the V-1 'Buzz Bomb', (German: Vergeltungswaffe 1, retaliation weapon), also colloquially known in Britain as the 'Doodlebug', was an early pulse-jet-powered example of what would later be called a cruise missile. The V-1 was developed at Peenemünde Airfield by the German Luftwaffe during the Second World War. The first of the so-called Vergeltungswaffen series designed for terror bombing of London, the V-1 was fired from "ski" launch sites along the French (Pas-de-Calais) and Dutch coasts. The first V-1 was launched at London on 13 June 1944, one week after (and prompted by) the successful Allied landing in Europe. At its peak, over a hundred V-1s a day were fired at southeast 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. This caused the remaining V-1s to be re-targeted on the port of Antwerp and other targets in Belgium, with 2,448 V-1s being launched. The attacks stopped when the last site was overrun on 29 March 1945. In total, the V-1 attacks caused 22,892 casualties (almost entirely civilians).

The underground V-1 storage depots at Saint-Leu-d'Esserent, Nucourt and Rilly-la-Montagne, as well as the launch sites, were bombed during Operation Crossbow.

Design and development

In the autumn of 1936 while employed by the Argus engine 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 1,000 kg over a distance of 500 km was forwarded to the RLM (German Air Ministry). Argus joined together 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 "Fernfeuer" to the RLM, as Project P 35 "Erfurt".

On 31 May Rudolf Bree of the RLM commented that he saw no chance that the project could be deployed in combat conditions, as the proposed remote control system was seen as a weakness of the design. Heinrich Koppenbrug, 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 opted to cancel it.

Despite this, Gosslau was convinced that the basic idea was sound and proceeded to simplify the design. As an engine manufacturer, Argus lacked capability to produce a fuselage for the project and Koppenburg sought the assistance of Robert Lusser, chief designer and technical director at Heinkel. On 22 January 1942 Lusser took up a position with the Fiesler aircraft company. He met with Koppenburg on 27 February 1942 and was informed of Gosslau's project. Gosslau's design used two pulse jet 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 1942 and the project was renamed to Fi 103 as Fiesler was to be the chief contractor. On 19 June 1942 Generalfeldmarschall Gerhard Milch gave Fi 103 production a high priority and development was undertaken at the Luftwaffe test centre at Karlshagen.

By 30 August 1942 Fiesler had completed the first fuselage, and the first unpowered flight of the Fi 103 V7 took place on 10 December 1942, when it was airdropped by a Fw 200.^[3]

Description

V-1 cutaway

The V-1 was designed under the codename Kirschkern (cherry stone)^[4] by Lusser and Gosslau, with a fuselage constructed mainly of welded sheet steel and wings built similarly or of plywood. The simple pulse jet engine pulsed 50 times per second,^[5] and the characteristic buzzing sound gave rise to the colloquial names "buzz bomb" or "doodlebug" (a common name for a wide variety of insects). It was known briefly in Germany (on Hitler's orders) as Maikäfer (june bug) and Krähe (crow).^[6]

Power plant

Ignition of the Argus pulse jet was accomplished using an automotive type sparkplug located about 2.5 ft (0.76 m) behind the intake shutters, with current supplied from a portable starting unit. Three air nozzles in the front of the pulse jet were at the same time connected to an external high pressure air source which was used to start the engine. Acetylene gas was typically used for starting, and very often a panel of wood or similar was held across the end of the tailpipe to prevent the fuel from diffusing and escaping before ignition.

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.

Rear view of V1 in IWM Duxford showing launch ramp section

It is a common myth that the V-1's Argus As 014 pulse jet engine needed a minimum airspeed of 150 miles per hour (240 km/h) to operate. The Argus As 014 (also known as a resonant jet) could in fact operate at zero airspeed due to the nature of its intake shutters and its acoustically tuned resonant combustion chamber. Contemporary film footage of the V-1 always shows the distinctive pulsating exhaust of a fully running engine before the catapult system is triggered and the missile launched.

The origin of the myth may lie in the fact that due to 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 required to either be launched by aircraft catapult or be airlaunched from a modified bomber aircraft such as the Heinkel He-111. Ground-launched V-1s were typically propelled up an inclined launch ramp by an apparatus known as a Dampferzeuger ("steam generator") which used hydrogen peroxide and potassium permanganate (T-Stoff and Z-Stoff).^[7] Takeoff speed was 360 mph (580 km/h).

Beginning in January 1941, the V-1's pulse jet engine was also tested on a variety of craft, including automobiles^[8] and an experimental attack boat known as the "Tornado". The unsuccessful prototype was a version of a 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 cross beams. 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.^[9]

Guidance system

A V-1 on display in Musée de l'Armée

The V-1 guidance system used a simple autopilot to regulate height and speed, developed by Askania in Berlin.^[10] A weighted pendulum system provided fore-and-aft attitude measurement to control pitch, (damped by a gyrocompass, which it also stabilized). Operating power for the gyroscope platform and also the flight control actuators was provided by two large spherical compressed air tanks which also pressurized the fuel tank. These air tanks were charged to 150 atm (15,000 kPa) before launch.

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 each of pitch and roll, but it was angled away from the horizontal so that controlling these degrees of freedom interacted: the gyroscope stayed trued up by feedback from a magnetic compass, 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 which landed in March 1945 without detonating between Tilburg and Goirle, The Netherlands, about 6 rolled 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. It is also known that several of the first buzz bombs to be launched were provided with a small radio transmitter (using a triode valve marked 'S3' but being 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.

An odometer driven by a vane anemometer on the nose determined when 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 60 km (37 mi).^[11] 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.^[12][13] 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 impacted under power.

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.

Operation and effectiveness

On 13 June 1944, the first V-1 struck London next to the railway bridge on Grove Road, Mile End, which now carries this plaque. Eight civilians were killed in the blast.

The first complete V-1 airframe was delivered 30 August 1942,^[14] and after the first complete As.109-014 was delivered In September,^[15] the first glide test flight was 28 October 1942 at Peenemünde, from under an FW-200 Kondor.^[16] The first powered trial was 10 December, launched from beneath an He-111.^[17]

A myth arose that early guidance and stabilisation problems were resolved by a daring test flight by Hanna Reitsch in a V-1 modified for manned operation. The myth entered popular consciousness from Reitsch's fictional exploits in the film Operation Crossbow.

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% 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.

The intended operational altitude was originally set at 2,750 m (9,000 ft). However, repeated failures of a barometric fuel-pressure regulator led to it being changed in May 1944, halving the operational height, thereby bringing V1s into range of the Bofors guns^[18] commonly used by Allied AA units.^[19]

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 Luftwaffe launched approximately 1,176 from modified Heinkel He 111 H-22s of the 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 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% failure rate of air-launched V-1s, and the He-111s used in this role were extremely vulnerable to night fighter attack, as the launch lit up the area around the aircraft for several seconds.

Experimental and long-range variants

A German crew rolls out their V-1

Late in the war, several air-launched piloted V-1s, known as Reichenbergs, were built, but never used in combat. Hanna Reitsch made some flights in the modified V-1 Fieseler 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 Reichenberg volunteer pilots. The Reichenbergs were air-launched rather than fired from a catapult ramp as erroneously portrayed in Operation Crossbow.

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 atop the aircraft. In the latter configuration, a pilot-operated hydraulic arrangement would lift the missile on its launch cradle some eight feet clear of the 234's dorsal fuselage. This was necessary to avoid damaging the mother craft when the pulse jet 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' for the Messerschmitt Me 262 jet fighter. The pulse-jet, 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.

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 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 Holland. Frantic efforts were made to construct sufficient F-1s so that a large-scale bombardment campaign could 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. Before the V-1 campaign ended for good at the end of the latter month, several hundred F-1s were launched at Britain from Dutch sites.

Almost 30,000 V-1s were made; by March 1944, they were produced in 350 hours (including 120 for the autopilot), at a cost of just 4% of a V-2,^[20] 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.^[21] The greatest density of hits were received by Croydon, on the southeast fringe of London.

Antwerp, Belgium was hit by 2,448 V-1s from October 1944 to March 1945.^[22]

Intelligence reports

V-1 in flight

The codename Flakzielgerät 76 - "Flak aiming apparatus" helped to hide the nature of the device, and it was some time 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. Especially the Polish Home Army intelligence contributed information on V-1 construction and a place of development (Peenemünde). Initially British experts were skeptical of the V-1 because they had considered only solid fuel rockets, which could not attain the stated range of 130 miles (209 km). 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.

Countermeasures

Anti-aircraft guns

The British defence against the German long-range weapons was Operation Crossbow. Anti-aircraft guns were 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 600 to 900 m (2,000 to 3,000 ft), 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, and faster-traversing static gun emplacements had to be built at great cost.

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 analog 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 percent of all flying bombs entering the coastal 'gun belt' were destroyed by guns in their first week on the coast. This rose to 60% by 23 August and 74% in the last week of the month, when on one day 82% 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. 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.^[23]

Interceptors

Fighters were mobilized to intercept the V-1, though most aircraft were too slow to catch a V-1 unless they had a height advantage, allowing them to gain speed by diving on the V-1 from altitude. Anti-V-1 sorties by allied aircraft were known as "Diver patrols" because of the tactic used. Hawker Tempests, Gloster Meteors and clipped-wing Spitfires were used on Diver patrols because these aircraft had sufficient speed to catch a V-1 and were also armed with 20mm cannon. Attacking a flying bomb was highly dangerous for pilots; solid machine gun bullets had little effect on the V-1's sheet steel structure, and if an explosive cannon shell detonated the warhead, the subsequent explosion could destroy the attacking fighter. The first interception of a V-1, by F/L JG Musgrave of No. 605 Squadron RAF, took place on the night of 14/15 June 1944.

The Defence Committee expressed some doubt as to the ability of the Royal Observer Corps adequately to deal with this 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 V-1 also lacked the primary points of vulnerability of conventional aircraft: pilot, life-support, and a complex engine. Hits to the pilot, oxygen system, or complex reciprocating engines of a piloted aircraft by a bullet or small shell fragment can destroy its fighting capability, but the V-1's Argus pulsejet provided sufficient thrust for flight even if damaged. The only vulnerable point of the Argus was the valve array at the front of the engine. The V-1's only one-shot stop points were the two bomb detonators and the line from the fuel tank — three very small targets buried inside the fuselage. A direct hit on the warhead by an explosive shell from a fighter's cannon, or a very close anti-aircraft shell explosion, were the most effective forms of gunfire.

A Spitfire using its wingtip to 'topple' a V-1 flying bomb

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 6 in (15 cm) 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 gyros and sending the V-1 into an out-of-control dive. At least three V-1s were destroyed this way. That the method was from time to time actually effective could be seen over southern parts of Holland when V-1s headed due eastwards at low altitude, the engine quenched. In early 1945 such a missile soared below clouds over Tilburg, Netherlands, only to gently alight eastwards of the city in open fields.

The Tempest fleet was built up to over 100 aircraft by September. Also, P-51 Mustangs and Griffon-engined Spitfire XIVs were tuned to make them almost fast enough, and during the short summer nights the Tempests shared defensive duty with de Havilland Mosquitoes. There was no need for airborne radar; at night the V-1's engine could be heard from 16 kilometres (10 mi) away or more, and the exhaust plume was visible from a long distance. Wing Commander Roland Beamont had the 20mm cannons on his Tempest adjusted to converge at 300 yd (270 m) ahead. This was so successful that all other aircraft in 150 Wing were thus modified.

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. Between June and 5 September 1944, the handful of 150 Wing Tempests shot down 638 flying bombs, with No. 3 Squadron RAF alone claiming 305. One Tempest pilot, Squadron Leader Joseph Berry, of No. 501 (Tempest) Squadron, shot down 59 V-1s, and Wing Commander Beamont destroyed 31.

Next most successful were the Mosquito (428), Spitfire XIV (303), 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.^[24] These were the first air combats between two jet-powered aircraft in history, although that achievement is usually ascribed to the battles between manned jet aircraft during the Korea War in the fall of 1950.

In late 1944 a radar-equipped Vickers Wellington bomber was modified for use by the RAF's Fighter Interception Unit as what would now be described as an Airborne Early Warning and Control aircraft.^[25] It operated at an altitude of some 4,000 feet over the North Sea to control Mosquito fighters intercepting He 111s flying from Dutch airbases for airborne launches of the V-1.

Deception

To adjust and correct settings in the V-1 guidance system, the Germans needed to know where the V-1s were landing. The V-1 operators asked German intelligence to get this impact data from agents in Britain. All these agents were double agents under British control (the Double Cross System), so the British sent deceptive data to the Germans.

V-1 impacts were often reported in the public press, so the British did not send false reports. Instead, they sent locations of actual impacts, especially those in central London, or "long" (to the northwest), but they omitted most of the impacts falling "short" (to the southeast). The Germans were thus induced to adjust their range settings down, shifting the "Mean Point of Impact" (MPI) away from central London to less populated areas.

In August 1944, the V-1 launch sites along the French coast were occupied by Allied forces. The Germans relocated V-1 operations to the Netherlands. When they resumed launching, their MPI was back in central London, but again the British deception shifted it elsewhere, this time to the east-north-east.

This deception operation suffered some interference from a German double agent in Portugal codenamed Arabel, who fraudulently claimed to have agents in Britain. He sent in a lot of fake impact reports which the Germans accepted. Fortunately, thanks to Ultra, the Allies read his messages and were able to adjust for them.^[26] He later approached the British intelligence service and served in counterintelligence. He was one of few people to be decorated for service by both the German and British governments in World War II.

The policy of diverting V-1 impacts away from central London was initially controversial. The War Cabinet refused to authorize a measure which 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.

Sir Findlater Stewart of Home Defence Executive then took responsibility for starting the deception program immediately. His action was approved by Churchill when he returned.^[27]

End of the V-1 attacks

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

In early December 1944, American General Clayton Bissell wrote a paper which argued strongly in favour of the V-1 compared to conventional bombers.^[28]

The following is a table he produced.

Doodlebug up close

Doodlebug on launcher

Japanese versions

In 1943, an Argus pulse jet 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 based on the Fieseler Fi-103 Reichenberg (Fi 103R, a piloted V-1), and was named Baika ("ume blossom").

Baika never left the design stage but technical drawings and notes suggest that two versions were under consideration: an air-launch version with the engine mounted under the fuselage, and a ground-launch version that could take off without a ramp.

Intelligence reports of the new "Baika" weapon are rumored to be the source of the name given to the Yokosuka MXY-7, a rocket-propelled suicide plane better known as the "Baka Bomb." However, as baka means "fool" in Japanese, and the MXY-7 was officially designated the "Ohka", the true origin is unknown. The MXY-7 was usually carried by the G4M2e version of the Mitsubishi G4M "Betty" naval bomber, then the pilot lit the solid-fuel rockets and guided his flying bomb into a ship.

Another Japanese Fi 103 version was the Mizuno Shinryu, a proposed rocket-powered kamikaze aircraft design, but it was not built.

Post-war

V-1 launch ramp recreated at Imperial War Museum, Duxford

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

France

The French produced copies of the V-1 for use as target drones. These were called the CT-10 and were smaller than the V-1 with twin tail surfaces. The CT 10 could be ground launched using a rocket booster or from an aircraft. Some CT-10s were sold to the UK and USA.

Soviet Union

The Soviet Union captured V-1s when they overran the Blizna test range in Poland. The 10Kh was their copy of the V-1, later called Izdeliye 10. Initial tests began in March 1945 at a test range in Tashkent with further launches from ground sites and from aircraft of improved versions continuing into the late 1940s. The inaccuracy of the guidance system compared to 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 pulse jet engine of the V-1 which began as a German project, the Junkers EF 126 Lilli^[29] , in the latter stages of the war. The Soviet development of the Lilli ended in 1946 after a crash that killed the test pilot.

United States

A KGW-1 being fired from USS Cusk in 1951

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-2s, were 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 2 1/2 inches wider and the length was extended less than 2 feet. The difference gave the JB-2 60.7 square feet of wing area versus 55 for the V-1.^[30]

A navalized version, designated KGW-1, was developed to be launched from LSTs (Landing Ship, Tank) 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 United States Invasion of Japan (Operation Downfall), however the atomic bombings of Japan negated its use.^[30] After World War II, 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

 Nazi Germany

• Luftwaffe

Survivors

War Memorial in Greencastle, Indiana

Australia

• The Australian War Memorial in Canberra, Australia.

Canada

• The Atlantic Canada Aviation Museum in Halifax, Nova Scotia.

Denmark

• The Danish defence museum Tøjhusmuseet

New Zealand

• Museum of Transport and Technology, Auckland.^[31][32]

United Kingdom

• Fi-103 serial number 442795 is on display at the Science Museum, London. It was presented to the museum in 1945 by the War Office.
• A V-1 can be seen up close, on a partial ramp section, within one of the public hangers (Battle of Britain display) in the Imperial War Museum Duxford. That appears to be the example shown in the photos below, with the yellow launch ramp.
• One is displayed along with a V-2 in the RAF Museum in Hendon, north London
• The RAF Museum Cosford (between Telford and Wolverhampton) also has a V1 on display.
• The Aeropark at East Midlands Airport also has a V1 on display.^[33]

United States

• JB-2 is on display at the National Museum of the United States Air Force in Dayton, Ohio. It was donated by the Continental Motors Corporation in 1957.^[34]
• JB-2 is on display at the Steven F. Udvar-Hazy Center in Chantilly, Virginia.
• FZG-76 is on display as a war memorial in Greencastle, Indiana.^[35]
• The National Air and Space Museum on the National Mall in Washington, D.C.
• The Planes of Fame air museum at Chino Airport in Chino, California has a JB-2 engine, restored to fully function.[1].
• A JB-2 Loon is on open-air display at the Museum of Alaska Transportation and Industry in Wasilla, Alaska.
• A JB-2 Loon is also on open-air display at the Point Mugu Missile Park at Naval Air Station Point Mugu in California.
• A V-1 is on display at the Air Zoo in Portage, Michigan.
• One is displayed, along with a V-2, at the Kansas Cosmosphere in Hutchinson, Kansas.
• A V-1 is also located at the Fantasy of Flight aviation museum in Polk City, FL.
• The U.S. Space & Rocket Center in Huntsville, Alabama displays a V-1 in their Rocket Park.

See also

References

Notes

Bibliography

External links

• V1 Launch Site
• Vergeltungswaffe V-Weapons – Archived version of Daniel Green's World War II Air Power website
• The V-Weapons – From Marshall Stelzriede's Wartime Story website; with June 1944 UK/US news reports on V-1 attacks
• Fi-103/V-1 "Buzz Bomb" – From the Luftwaffe Resource Center website, hosted by The Warbirds Resource Group; with 42 photos
• The Lambeth Archives Includes a sound recording of an incoming V1 - circa 1944
• Site with casualty numbers in South London