V-1 flying bomb

V1
V-1 flying bomb First modern cruise missile
Description
Role	Flying bomb
Crew	none
Dimensions
Length	7.90 m	25 ft 11 in
Wingspan	5.37 m	17 ft 7 in
Height	1.42 m	4 ft 8 in
Wing area
Weights
Empty
Loaded	2,150 kg	4,750 lb
Powerplant
Engine	1x Argus As 14 pulsejet
Thrust	2.9 kN	660 lbf
Performance
Maximum speed	656 km/h	410 mph
Range	240 km	150 mile
Service ceiling	3,050 m	10,000 ft
Rate of Climb
Armament
Amatol warhead	830 kg	1,832 lb

The Vergeltungswaffe 1 Fi 103 / FZG-76 (V-1), known as the Flying bomb, Buzz bomb or Doodlebug, was the first modern guided missile used in wartime and the first cruise missile. Vergeltungswaffe means "reprisal weapon", and FZG is an abbreviation of Flak Ziel Gerät ("anti-aircraft aiming device"), a misleading name.

Called the Buzz bomb because of the Missing image
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Image:Ltspkr.png

characteristic buzzing sound of the engine, it caused considerable fear in targeted areas. People would listen for the missile approaching, but then be relieved when it could be heard overhead as that meant it had actually passed them. If the engine noise cut out, it was time to take cover, as the unpowered missile would go into its terminal dive and explode.

The V-1 was developed by the German Luftwaffe during the Second World War and was used operationally between June 1944 and March 1945. It was used to attack targets in south-eastern England and Belgium, mainly the cities of London and Antwerp. V-1s were launched from "ski-jump" launch sites along the French (Pas-de-Calais) and Dutch coasts until they were over-run by Allied forces. It was later complemented by the more sophisticated V-2 rocket.

Contents

1 Description

2 Operation and effectiveness

Description

The V-1 was designed jointly by Robert Lusser of the Fieseler company and Fritz Gosslau from the Argus engine works as the Fi 103. It was powered by an Argus pulse jet engine providing 2.9 kN (660 lbf) of thrust for a top speed of 630 km/h (390 mph) and a range of around 250 km (150 mile) later 400 km (250 mile). It was 7.9 m (26 ft) long, 5.3 m (17 ft) in span and weighed 2,180 kg (4,800 lb). It flew at an altitude of between 100 to 1000 m (300 to 3000 ft). It carried a 850 kg (1,870 pound) warhead. The missile was a relatively simple device with a fuselage constructed mainly from sheet metal, and could be assembled in around fifty man-hours.

The guidance system was very crude in construction but sophisticated in conception (and had a few flaws in execution). Once clear of the launching pad, an autopilot was engaged. It regulated height and speed together, using a weighted pendulum system to get fore and aft feedback linking these and the device's attitude to control its pitch (damped by a gyromagnetic compass, which it also stabilized). There was a more sophisticated interaction between yaw, roll, and other sensors: a gyromagnetic compass (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 the magnetic field, and from the fore and aft pendulum mentioned before). This interaction meant that rudder control was sufficient without any separate banking mechanism. On reaching the target, the desired altitude was reset to be negative; this should have led to a power dive, but the steep descent caused the fuel to run away from the pipes and so the power cut out. As there was a belly fuse as well as a nose fuse, there was still usually an explosion, although not always with the device buried deep enough to increase the effect of the blast.

Operation and effectiveness

The first test flight of the wonder weapon V-1 was in late 1941 or early 1942 at Peenemünde. Early guidance and stabilization problems were finally resolved by a daring test flight by Hanna Reitsch, in a V-1 modified for manned operation. The data she brought back after fighting the unwieldy V-1 down to a successful landing enabled the engineers to devise the stabilization system described above.

Final dive of a V-1 over London

The first offensive launch was from June 12 to June 13, 1944. The Allies had previously organized a heavy series of air attacks on the launch sites (beginning in December 1943) and now also attacked the V-1s in flight (see Countermeasures below). Due to a combination of defensive measures, mechanical unreliability and guidance errors, only a quarter successfully hit their targets.

Once the Allies had captured or destroyed the sites that were the principal launch points of V-1s aimed at England, the Germans switched to missile launches aimed at strategic points in the Low Countries, primarily the port of Antwerp.

Although most V-1s were launched from static sites on land, from July 1944 to January 1945 the Luftwaffe launched a number of V-1s from Heinkel He 111 aircraft flying over the North Sea. This would also have been the launch method for the proposed piloted version of the weapon, and is how the very earliest experimental versions of the V-1 were tested. Late in the war, it was hoped to use the Arado Ar 234 jet bomber to deploy V-1s, either by towing them aloft, or by launching them from a "piggy back" position atop the aircraft. Neither Ar 234 concept was employed before the end of the war.

Almost 30,000 V-1s were manufactured. Approximately 10,000 were fired at England up to March 29, 1945. Of these, about 7,000 were "hits" in the sense that they landed somewhere in England. A little more than half of those (3,876) landed in the Greater London area.

An almost equal number were shot down or intercepted by barrage balloons. When the V-1 raids began, the only effective direct defense was interception by a handful of very high performance fighter aircraft, in particular the Hawker Tempest. The British were able to redirect V-1's aimed at London to less populated areas east of the city by sending false impact reports via the German espionage network in Britain, which was actually controlled by the British. See: Double Cross System.

In the London area, roughly 5,500 people died as a result of V-1 attacks, with some 16,000 more people injured.

Intelligence

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V-1 diving

The codename Flak Ziel Gerät 76, was somewhat successful in disguising the true nature of this device, and it was some time before references to FZG 76 were tied to the V83 pilotless aircraft (an experimental V-1) which had crashed on Bornholm in the Baltic, and to reports from agents of a flying bomb capable of being used against London. Initially British experts were skeptical of the V-1 because they had considered only solid fuel rockets as a means of propulsion, which put the stated range of 130 miles (209 km) out of question. However when other types of engine were considered they relented, and by the time German scientists had achieved the needed accuracy for the deployment of the V-1 as a weapon British intelligence had a very accurate characterisation of it.

A deception concerning the V-1 was played on the Germans using double agents. MI5 arranged for these agents to provide Germany with damage reports for the June 1944 V-1 attacks which implied that on average the bombs were travelling too far, while not contradicting the evidence presumed to be available to German planners from photographic reconnaissance of London. In fact the bombs had been seeded with radio-transmitting samples to confirm their range, but the results from these samples were ignored in favour of the false eye-witness accounts, and many lives may have been saved by the resulting tendency of future V-1 bombs to fall short of built up areas.

Countermeasures

The British defence against the V-1 was codenamed Operation Diver. 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 Linconshire-Yorkshire coast. The deployments were prompted by the ever-changing approach tracks of the missiles which were in turn influenced by the Allies' advance through Europe.

Anti-aircraft gunners found that such small, fast-moving targets were difficult to hit. At first, it took, on average, 2500 shells to bring down a single V-1. The average altitude of the V-1, between 2,000 and 3,000 feet, was in a narrow band between the optimum engagement heights for light and heavy anti-aircraft weapons. These low heights defeated the rate of traverse of the standard British 3.7 inch mobile gun, and static gun installations with faster traverses had to be built at great cost.

Barrage balloons were also deployed against the missiles, but the leading edges of the V-1's wings were equipped with balloon cable cutters and fewer than 300 V-1s are known to have been destroyed by hitting cable.

Fighter defences had also been mobilized as part of Operation Diver. Most fighter aircraft were too slow to catch a V-1 unless they had a useful height advantage. Even when intercepted, the V-1 was difficult to bring down. Machine gun bullets had little effect on the sheet steel structure, and 20 mm cannon shells had a shorter range, which meant that detonating the warhead could destroy the intercepting fighter as well.

When the attacks began in mid-June of 1944 there were fewer than 30 Tempests in 150 Wing to defend against them. Few other aircraft had the low altitude performance to be effective. Initial attempts to intercept V-1s were often unsuccessful but interdiction techniques were rapidly developed. (These included the hair-raising but effective method of using the airflow over an interceptor's wing to raise one wing of the Doodlebug, by sliding the interceptor's wingtip under the V-1's wing and bringing it to within six inches of the lower surface. Done properly, the airflow would tip the V-1's wing up, overriding the buzz bomb's gyros and sending it into an out of control dive. At least three V-1s were destroyed this way.)

The Tempest wing was built up to over 100 aircraft by September; Griffon-engined Spitfire XIVs and Mustangs were polished and tuned to make them almost fast enough, and during the short summer nights the Tempests shared defensive duty with Mosquitoes. Specially modified P-47 Thunderbolts (P-47Ms) with half their fuel tanks, half their 0.5 in (12.7 mm) machine guns, all external fittings and all their armor plate removed were also pressed into service against the V-1 menace. (There was no need for radar—at night the V-1's engine could be seen from 16 km (10 mile) or more away.)

In daylight, V-1 chases were chaotic and often unsuccessful until a special defence zone between London and the coast was declared in which only the fastest fighters were permitted. Between June and mid-August 1944, the handful of Tempests shot down 638 flying bombs. (One Tempest pilot, Joseph Berry, downed fifty-nine V-1s, another 44, and Wing Commander Roland Beamont destroyed 31.) Next most successful was the Mosquito (428), Spitfire XIV (303), and Mustang, (232). All other types combined added 158. The still-experimental jet-powered Gloster Meteor, which was rushed half-ready into service to fight the V-1s, had ample speed but suffered from a readily jammed cannon and accounted for only 13.

By mid-August 1944, the threat was all but overcome—not by aircraft, but by the sudden arrival of two enormously effective electronic aids for anti-aircraft guns, both developed in the USA by the Rad Lab: radar-based automatic gunlaying, and above all, the proximity fuse. Both of these had been requested by AA Command and arrived in numbers, starting in June 1944, just as the guns reached their free-firing positions on the coast.

Seventeen per cent of all flying bombs entering the coastal 'gun belt' were destroyed by guns in the first week on the coast. This kill rate rose week on week to reach 60 per cent by 23 August and 74 per cent in the last week of the month, when on one extraordinary day 82 per cent of all targets available to the guns fell. The kill rate increased from one V-1 for every 2500 shells fired to one for every hundred.

Japanese Versions

In 1944 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" (Fi103R ) manned V-1, and was named the Baika ("plum blossom").

The Kawanishi 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.

After the War

After the war, the armed forces of both the United States and the Soviet Union experimented with the V-1 in an assortment of scenarios. The most successful was a U.S. Navy experiment to mount V-1s on submarines. This was called the KGW-1 Loon, which was an adaptation of the U.S. Army's JB-2 Loon.

References

King, Benjamin; Kutta, Timothy (1998). IMPACT. The History of Germany's V-Weapons in World War II. Rockville Center, New York: Sarpedon Publishers. ISBN 1-885119-51-8.

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