[10] Erhard Milch, State Secretary in the Reich Ministry of Aviation and Inspector General of the Air force, awarded Argus the contract for the engine, Fieseler the airframe, and Askania the guidance system.

[16] The Argus pulsejet's major components included the nacelle, fuel jets, flap valve grid, mixing chamber venturi, tail pipe, and spark plug.

The flaps momentarily closed after each explosion, the resultant gas compressed in the venturi chamber, and its tapered portion accelerated the exhaust gases creating thrust.

[22] Two spherical tanks contained compressed air at 6.2 megapascals (900 psi), that drove the gyros, operated the pneumatic servomotors controlling the rudder and elevator, and pressurized the fuel system.

[49] Launches against Britain were met by a variety of countermeasures, including barrage balloons and aircraft such as the Hawker Tempest and newly introduced jet Gloster Meteor.

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.

The combat potential of air-launched V-1s dwindled during 1944 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.

A somewhat less ambitious project undertaken was the adaptation of the missile as a "flying fuel tank" (Deichselschlepp) for the Messerschmitt Me 262 jet fighter, which was initially test-towed behind an He 177A Greif bomber.

A small cylindrical module, similar in shape to a finless dart, was placed atop the vertical stabiliser at the rear of the tank, acting as a centre of gravity balance and attachment point for a variety of equipment sets.

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.

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.

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.)

[59][60] The codename "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.

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.

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.

[citation needed] 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.

[64][d] 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.

[66] As General Frederick Pile put it in an April 5, 1946 article in the London Times: "It was the proximity fuse which made possible the 100 per cent successes that A.A. Command was obtaining regularly in the early months of last year...American scientists...gave us the final answer to the flying bomb.

Fighter aircraft required excellent low altitude performance to intercept them and enough firepower to ensure that they were destroyed in the air (ideally, also from a sufficient distance, to avoid being damaged by the strong blast) rather than the V-1 crashing to earth and detonating.

[75] 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.

[76] Flying at an altitude of 100 ft (30 m) over the North Sea at night, it directed Mosquito and Beaufighters charged with intercepting He 111s from Dutch airbases that sought to launch V-1s from the air.

However, the double agents would have been endangered because there was no plausible reason why they 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.

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 ..."[79] While the British decided how to react, Pujol played for time.

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.

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.

[27] In early December 1944, American General Clayton Bissell wrote a paper that strongly demonstrated the cost-effectiveness for the Germans of the V-1 when compared with conventional bombers.

General Hap Arnold of the United States Army Air Forces was concerned that this weapon would make his long-range bombers less important, since they were much cheaper and could be built of steel and wood, in 2,000 man-hours and approximate cost of US$600 (in 1943).

It was essential logistically for the further progression of Allied armies into Germany,[94] although initially Montgomery had not given high priority to seizure of the Scheldt estuary giving access to the port.

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.

[105] 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 Lilli, in the latter stages of the war.