The Atlantik Wall In Normandy

 

 

V1 Flying Bomb History

While the history of the cruise missile was marked by failures and false starts until modern times, one early attempt to build and operate such a weapon became notorious: the German V1 flying bomb, developed during World War II.

The Germans had performed experiments with auto piloted aircraft in the 1930s, but proposals made to the German military in 1939 and 1941 to develop operational flying bombs were turned down.

In June 1942, however, intensified Royal Air Force (RAF) bomb raids on German cities and rising losses of Luftwaffe bombers over England, in attempts to retaliate, persuaded the Luftwaffe to consider new options.

Work on the V-2 long-range rocket was encountering difficulties, and the V-2 was an Army project in any case. 

The Luftwaffe investigated and approved the development of a small, cheap flying bomb, with a range of about 250 kilometers (155 miles) and an 800 kilogram (1,764 pound) warhead, that could target a city-sized area, evading interception by flying in at high speed and low altitude. The project was given the cover designation of “Flak Ziel Geraet” (FZG), or anti aircraft target apparatus’’. 

Propulsion for the new flying bomb was provided by the “pulse jet”, which had been invented by Paul Schmidt in the early 1930s, and had been under development by the Army Weapons Office since 1937. The pulse jet was little more than a “stovepipe”, with its sole moving part consisting of a shutter assembly inside the air intake.

The simplicity and low cost of this engine was a major factor in the Luftwaffe’s decision to pursue flying bomb development. ( A V2 costs six times as much)

Air entering into the pulse jet was mixed with fuel and the mixture ignited by spark plugs. The combustion of the mixture slammed the intake shutters closed, and produced a burst of thrust, out of the exhaust. The shutters then opened again in the airflow.

The production engine would perform this cycle about 42 times a second.

This pulsed operation caused the engine to emit a loud low buzzing sound that would presently become familiar over the English countryside.

However, a pulse jet requires a compressed airflow to start and operate, and had no means of generating such a flow itself. Any aircraft propelled by such an engine has to be externally accelerated to at least 300 KPH (190 MPH) before it can actually fly on its own.

Despite this limitation, the pulse jet had major advantages. It was simple, cheap, and powerful, with a thrust of 270 kilograms (600 pounds).

Furthermore, it could use low-grade gasoline as a fuel, rather than precious high octane aviation fuel. The pulse jet was also limited by the fact that throttling it was difficult at best, and that the shutters tended to wear out quickly, but neither of these issues were important in an expendable weapon.

Three companies collaborated in building the flying bomb. Fiesler built the airframe; Argus, which employed Paul Schmidt, built the pulse jet engine; and Askania built the guidance system. A glide test was performed from a Focke-WulfFW-200 in early December 1942, followed by a powered flight on Christmas Eve.

The initial powered flight only went a kilometer, and the early prototypes showed a distressing tendency to crash. To resolve these problems, a piloted flying bomb was developed, in which the warhead was replaced by a cockpit in which a test pilot could fly the machine while lying prone.

Test flights were performed with the tiny and daring female test pilot Hanna Reitsch at the controls, and helped resolve the defects in the machine. 

On 26 May 1943, top Nazi officials visited the test facility at Peenemunde, on the Baltic, to evaluate progress on the flying bomb. They concluded that the weapon should be put into full-scale production, and work was accelerated on completing development, establishing an operational unit to fire the weapons, and constructing launch sites. There were to be a hundred launch sites in the Pas de Calais area in France, capable of launching a thousand flying bombs a day. London was only about 200 kilometers (120 miles) from the launch sites.

The flying bomb was refined into a production prototype version, code named “Kirshkern” (Cherrystone), that was much superior to the initial prototypes. In production, the weapon was officially designated the Fiesler Fi-103 or FZG-76, but was more informally referred to as the V1, for Vergeltungswaffe Einz, or Vengeance Weapon 1. 

RAF photo-reconnaissance aircraft had been observing the strange goings-on at Peenemunde since the middle of May 1942, and though Allied intelligence wasn’t sure about what was going on, the Germans were clearly up to no good. The RAF launched a heavy attack on Peenemunde in the late summer of 1943, though it did not greatly slow down German development efforts. Shortly thereafter, the United States Army Air Force bombed the launching sites in the Pas de Calais and almost completely destroyed them. 

On 28 November 1943, an RAF photo-reconnaissance aircraft took pictures of Peenemunde, and a sharp-eyed photographic analyst, Flight Officer Babington Smith, spotted a prototype flying bomb on a launch ramp at Peenemunde. British intelligence began to see what the Germans were up to. British intelligence estimates indicated that the Germans would be able to start launching these new weapons against England in a matter of weeks, and attacks on new launch sites under construction were stepped up.

However, by this time the flying bomb was in production, and the new launch sites were more easily concealed. Several flying bombs were launched towards Sweden to determine their range and other performance characteristics, and on 13 June 1944, the first V1 s were launched towards London.

Only about ten missiles were fired that day, and they were only fired because the commandant in charge of the launch sites had been ordered to. He was not quite ready to begin full scale launch operations at that time, so he simply did as he was ordered, then returned to finishing his preparations. 

The flying bomb blitz began in earnest on 15 June, with 244 fired at London and 50 fired at Southampton. 144 crossed the English coast, 73 managed to reach London with some shot down and most of the rest landing south of the Thames, and a few hit Southampton. One went wildly astray and ended up in Norfolk. 

The V1 itself was an odd and ingenious aircraft, designed to be cheaply produced in large quantities. It had a wingspan of 5.4 meters (17 feet 8 inches), a length of 8.3 meters       (27 feet 4 inches), and weight of 2,160 kilograms (4,760 pounds), including an 850 kilogram (1,870 pound) Amatol warhead. Early production was largely made of metal, though wooden wings were quickly introduced.

The weapon was directed to its target by a simple guidance system, based on a gyroscope system driven by compressed air to keep the missile stable, a magnetic compass to control bearing, and barometric altimeter to control altitude.  

Maximum speed was around 645 Kph (400 MPH). It was typically set to fly at an altitude of about 600 meters (2,000 feet), using the barometric altimeter as a reference. A spinner on the nose armed the warhead after about 100 kilometers (60 miles) of flight, and determined when the weapon would fall to earth. However, a few documents state that rather than using a nose spinner this function was performed by a simple clock.  Illustrations are ambiguous on this issue, and it is very possible that different production runs used different systems.

The little aircraft’s wings had no control surfaces. The VI was directed by the rudder and elevators of its tail assembly. This was a crude means of control, but since there was no possibility of maneuvering anyway, it was adequate as well as cheap.  

When the guidance system determined that it was at the target point, it locked the control surfaces, the elevators put the V1 into a steep dive. Usually, though not always, this would stall the engine. The abrupt cessation of the loud buzz inspired terror, since it meant there would be a terrific explosion a few moments later.  

The V1’s warhead used three fuzes, including an electrical fuze, a backup mechanical fuze, and a time-delay fuze to ensure that the weapon destroyed itself if the other fuses failed to work. The fuzing system was very reliable, and very few V1s failed to explode.  

Early V1 production items had a fuel capacity of 640 litters (169 US gallons), providing a maximum range of 260 kilometers (163 miles).

Flight time from launch to impact was usually about 22 minutes. Accuracy was very poor, with impacts scattered all over south-eastern England.

 

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