V-1 flying bomb

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The Vergeltungswaffe-1, V-1, also designated Fieseler Fi 103/FZG-76, known colloquially in English as the Flying bomb, Buzz bomb or Doodlebug, was the first guided missile used in war and the forerunner of today's cruise missile.

The name Vergeltungswaffe, meaning "reprisal weapon", was coined by German propaganda minister Goebbels to signify reprisal against the Allies for the bombing of the Fatherland. FZG is an abbreviation of Flakzielgerät (anti-aircraft gun aiming device), a designation chosen to mislead.

The V-1 was developed by the German Luftwaffe during the Second World War and was used between June 1944 and March 1945. It was fired at targets in southeastern England and Belgium, chiefly London and Antwerp. V-1s were launched from "ski-jump" launch sites along the French (Pas-de-Calais) and Dutch coasts until the sites were overrun by Allied forces. A small number were air-launched from German aircraft over the North Sea. The V-1 was later complemented by the more sophisticated V-2 rocket. The last V-1 struck British soil on March 29, 1945, two days after the last V-2 struck.

V-1
A V-1 at the National Air & Space Museum
Type	Flying bomb
Manufacturer	Fieseler
Designed by	Robert Lussar
Maiden flight	late 1941
Retired	1950s
Primary user	Luftwaffe

Contents 1 Background 2 Description 2.1 Guidance system 3 Operation and effectiveness 4 Intelligence reports 5 Countermeasures 6 Assessment 7 Japanese versions 8 After the War 8.1 France 8.2 Soviet Union 8.3 United States 9 Common misconceptions 10 Specifications 11 See also 12 References 13 External links

[edit] Background

When launched, the V-1s flew without human intervention to strike distant targets. The V-1 was a small pilotless aircraft with minimal guidance and a large warhead.

The V-2 ballistic missile was unmanned but far more sophisticated technologically. Both weapons could hit a city-sized target but accuracy greater than this was rare. They failed to turn the tide of war but forced the Allies to devote large amounts of time and resources against them.

Although the Kettering "Bug" Aerial Torpedo, a small propeller-driven flying bomb developed towards the end of World War I, was a pilotless military aircraft that could have functioned as a primitive cruise missile, the V-1 is often thought of as the first cruise missile comparable to modern missiles in terms of design, guidance systems, and propulsion.

[edit] Description

The V-1 was designed by Robert Lussar of the Fieseler company and Fritz Gosslau from the Argus engine works as the Fi 103. It was powered by an Argus As 014 pulse jet engine providing 2.9 kN (660 lbf) of thrust for a top speed of 630 km/h (390 mph) and an average range of around 250 km (150 miles)^[1], which was later increased to 400 km (250 miles). It was 7.9 meters (25.5 feet) long and 5.3 meters (17 feet 6 inches) in span and weighed 2180 kilograms (4,800 pounds). It flew at an altitude of 100 to 1000 meters (300 to 3,000 feet). It carried an 850-kilogram (1,870-pound) warhead and held 150 gallons of fuel^[2]. The missile was a relatively simple device, with a fuselage constructed mainly of welded sheet steel, with wings built similarly or of plywood, and could be assembled in around 50 man-hours.

Pulsejets are the simplest of subsonic jet engines, little more than a one-way air intake valve, a combustion chamber, and a fuel system. The engine cannot start until the airspeed is sufficient to force air into the combustion chamber at sufficient pressure. In operation fuel is squirted into the combustion chamber as air is forced in from the front through a shutter forming a one-way intake valve. Igniting the fuel-air mixture results in an explosion that closes the intake shutter, so that the expanding gases must exit via the rear nozzle, propelling the missile. As pressure drops in the combustion chamber, the airflow forces open the front shutter. The process is repeated 50 times per second^[3]. This produces a characteristic buzzing sound, which gave rise to the colloquial names "buzz bomb" or "doodlebug" (after an Australian insect).

The V-1's pulsejet engine needed a minimum airspeed of 150 mph (241.4 kph); this was attained by launching from a ground ramp, using a chemical or steam catapult which accelerated the V-1 to 200 mph, or from a moving aircraft^[4].

[edit] Guidance system

Its guidance system was crude in construction, sophisticated in conception, and somewhat flawed in execution. Once clear of the launching pad, an autopilot was engaged. It regulated height and speed, using a weighted pendulum system to get fore-and-aft feedback, linking these and the V-1'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. This interaction meant that rudder control was enough without a separate banking mechanism.

It had a small unpowered propeller on the nose, connected to a counter preset to a number which would determine the range. Before launch the counter was set to a value that would reach zero upon arrival at the target in the prevailing wind conditions, which was accurate enough for area bombing. This determined how far the missile would fly; it was simply launched in the right direction and controlled by its autopilot from then.

As the missile flew, the airflow turned the propeller; every 30 rotations of the propeller would count down one number on the counter. This counter triggered the arming of the warhead after about 38 miles^[5]. When the count reached zero, a solenoid attached to a small guillotine was activated, cutting the air hose from the servo to the rear elevator and allowing a spring to fully depress the elevator causing the V-1 to dive^[6]. While this was originally intended to be a power dive, in practice the onset of the dive caused the fuel flow to cease, which stopped the engine; this was perfectly effective, and the sudden silence after the buzzing alarmed listeners, who thus knew that it would impact soon.

There were fuses in the nose and the belly, one or other of which was usually activated on impact, detonating the warhead immediately; damage would have been worse if a time delay allowed the bomb to penetrate before detonation.^{[citation needed]} Sometimes the dive system failed and the missile coasted in on a flat trajectory, leading to the false idea that there were two versions.

The V-1 has been said to be the first cruise missile.

[edit] Operation and effectiveness

The first test flight of the V-1 was in late 1941 or early 1942 at Peenemünde. Early guidance and stabilisation problems were 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 stabilisation system. The idea of a piloted V-1 as a suicide weapon sprang from this mission: see Selbstopfer.

First operational use was on June 12 and 13, 1944, after a series of heavy Allied air attacks (Operation Crossbow) on the launch sites beginning in December 1943. The launch sites could theoretically launch about 15 bombs per day, although this was never consistently achieved; the record was 18 in one day. Only a quarter hit their targets due to a combination of defensive measures (see Countermeasures below), mechanical unreliability and guidance errors.

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.

The earliest experimental 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 111H-22s flying with the Luftwaffe's 3rd Bomber Wing or Kampfgeschwader 3 (the so-named "Blitz Wing") flying over the North Sea. 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.

Late in the war several air-launched piloted V-1s, known as Reichenbergs, were built, but never used in combat. There were plans, not carried 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..

Almost 30,000 V-1s were made. Approximately 10,000 were fired at England up to March 29, 1945; 2,419 reached London, killing about 6,184 people and injuring 17,981 [1].

[edit] Intelligence reports

See also Home Army and V1 and V2.

The codename Flak Zielgerät 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 V83 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. 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.

The lack of German intelligence from Britain enabled British Military Intelligence, MI5, to deceive the Germans about the range of the V-1, causing many to fall short of their targets in London. A number of German agents (all of them, it transpired after the war) had been captured by the British and induced to act for Britain as double agents: the Double Cross System. These agents provided Germany with false damage reports for the June 1944 V-1 attacks. The reports supplied correct accounts of damage (which could be checked by German photo-reconnaissance), but incorrect impact times, so that damage from another attack was attributed to a V-1 overshooting its target. Although a number of the bombs had been fitted with radio transmitters to confirm their range, the agents' reports were believed and later V-1s set to travel less far, probably preventing considerable loss of life and damage.

[edit] 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 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.

Anti-aircraft gunners found that such small fast-moving targets were difficult to hit. The cruising altitude of the V-1, between 2,000 and 3,000 feet (600 to 900 m), 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 centimetric gun-laying radars based on the cavity magnetron and of the proximity fuze helped defend against the V-1's high speed and small size. In 1944, Bell Labs started delivery of an anti-aircraft predictor fire-control system based around an analog computer, just in time for the Allied invasion of Europe.

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.

Fighters were mobilized to intercept the V-1 as part of Operation Diver. Most fighter aircraft were too slow to catch a V-1 unless they had a height advantage, allowing them to gain speed by diving. Even when intercepted, the V-1 was difficult to bring down. 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 explosion could destroy the attacking fighter. The first interception of a V-1, by F/L JG Musgrave of 605 Squadron, took place on the night of 14/15 June 1944.

The V-1 also lacked the primary points of vulnerability of conventional aircraft: pilot, life-support, and 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.

When V-1 attacks began in mid-June of 1944, there were fewer than 30 Tempests, the only aircraft with the low-altitude speed needed to be effective against the V-1; they were assigned to 150 Wing. Early attempts to intercept and destroy V-1s often failed, but improved techniques soon emerged. These included the hair-raising method of using the airflow over an interceptor's wing to raise one wing of the Doodlebug, by sliding the wingtip to within six inches (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.

The Tempest wing was built up to over 100 aircraft by September; 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 Mosquitoes. There was no need for radar — at night the V-1's engine could be heard from 16 km (10 miles) or more away, and the exhaust plume was visible from a long distance. Wing Commander Roland Beamont had the 20 mm cannons on his Tempest harmonised at 300 yards (275 m) (i.e. set to fire at the same spot 300 yards 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 alone claiming 305. One Tempest pilot, Squadron Leader Joseph Berry of No. 501 (Tempest) Squadron, shot down 59 V-1s, and Wing Commander Roland 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 616 Squadron to fight the V-1s. It had ample speed but its cannons were prone to jamming, and it shot down only 13 V-1s.

In mid-1944 the V-1 threat was drastically reduced by the arrival of two very effective electronic aids for anti-aircraft guns requested by AA Command, both developed in the USA by the MIT Rad Lab: radar-based automatic gunlaying (using the SCR-584 and other radars), and the proximity fuze.

These electronic aids arrived in quantity from June 1944, just as the guns reached their firing positions on the coast. 17% 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.

By September 1944, the V-1 threat to England ended when all launch sites were overrun by the advancing Allied Armies. 4,261 V-1s had been destroyed by fighters, anti-aircraft fire and barrage balloons.

[edit] Assessment

In early December 1944, General Clayton Bissell paper which argued strongly in favour of the V1 compared to conventual bombers ^[7]

The following is a table he produced

Blitz (12 months) vs V1 flying bombs (2¾ months)

	Blitz	V1
1. Cost to Germany
Sorties	90,000	8,025
Weight of bombs tons	61,149	14,600
Fuel consumed tons	71,700	4,681
Aircrafts lost	3,075	0
Men lost	7690	0
2. Results
Houses damaged/destroyed	1,150,000	1,127,000
Casualties	92,566	22,892
Rate casualties/bombs tons	1.6	4.2
3. Allied air effort
Sorties	86,800	44,770
Planes lost	1,260	351
Men lost	805	2,233

[edit] 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 (Fi103R, 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" ("Cherry Blossom"), 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. During the Boeing B-29 firebomb attacks on Japanese cities, the Baka was deployed against American bombers.

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

[edit] After the War

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

[edit] 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.

[edit] 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 in the latter stages of the war. This was called the EF-126 but development ended in 1946 after a crash that killed the test pilot.

[edit] United States

The 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 Doodle Bug. The JB-2, built by Republic Aviation (airframe) and Ford Aerospace (pulsejet engine), was reverse-engineered by inspecting V-1 wreckage found in England and was first flight-tested less than four months after the first V-1 attack. While the first flights were from Eglin AAF, Florida, extensive testing was also done at Wendover Army Air Field in Utah, launching only a few hundred feet from the sheds where delivery methods for the first atomic bombs were being developed under Project Alberta. The JB-2 was intended as a weapon in the planned invasion of Japan, but Japan surrendered after the atomic bombing of Hiroshima and Nagasaki and the invasion did not take place. Following the war, testing at Wendover continued, including comparison tests between the original German missile and the American copy. Later, preliminary design work was done on a small atomic warhead to be fitted to the JB-2, but it was never built.

The American flying bombs were used to test and gain operational experience with what were later called cruise missiles. The US briefly considered using the Loon in the Korean War against North Korean targets.

[edit] Common misconceptions

It is very commonly stated, even in otherwise accurate texts, that the V-1 dived onto its target when its fuel ran out. This description seems almost as prevalent as correct accounts of the V-1's guidance system. This idea almost certainly arose because of the engine cut-off associated with the missile's final dive.

[edit] Specifications

General characteristics

• Length: 7.90 m (25 ft 11 in)
• Diameter: ()
• Launch mass: 2,150 kg (4,750 lb)

Engine

• First stage: 1× Argus As 14 pulsejet
  • Thrust: 2.9 kN (660 lbf)

Performance

• Cruise speed: 656 km/h (knots, 410 mph)
• Operating altitude: 3,050 m (10,000 ft)
• Range: 241 km (nm, 151 mi)

Warhead

• Warhead: Amatol warhead

[edit] See also

Articles:

• Selbstopfer – The piloted version of the V-1
• List of missiles
• List of World War II guided missiles of Germany
• List of World War II jet aircraft
• Ivan A. Getting

[edit] References

1. ^ The Evolution of the Cruise Missile by Werrell, Kenneth P. see PDF page 53
2. ^ The Evolution of the Cruise Missile by Werrell, Kenneth P. see PDF page 54
3. ^ The Evolution of the Cruise Missile by Werrell, Kenneth P. see PDF page 53
4. ^ The Evolution of the Cruise Missile by Werrell, Kenneth P. see PDF page 53
5. ^ The Evolution of the Cruise Missile by Werrell, Kenneth P. see PDF page 54
6. ^ German V1 Leaflet Campaign
7. ^ Hitler's terror weapons by Roy Irons: The price of vengeance page 199

• 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.

• Ramsay, Winston; 'The Blitz Then & Now'(Volume 3). 1990 Battle of Britain Prints International. ISBN 0-900913-58-4

• Zaloga, Steven; 'V-1 Flying Bomb 1942-52'. 2005 Osprey Publishing. ISBN 1-84176-791-3

[edit] External links

• http://coalhousefort-gallery.com/V1-flying-bomb-Vengance-weapon-site-Hazebrouck V1 Launch Site
• Vergeltungswaffe V-Weapons – From Daniel Green's World War II Air Power website; contains descriptions and film sequences (AVI format)
• 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