Operation and Effectiveness
The first complete V-1 airframe was delivered 30 August 1942, and after the first complete As.109-014 was delivered in September, the first glide test flight was 28 October 1942 at Peenemünde, from under a Focke-Wulf Fw 200. The first powered trial was 10 December, launched from beneath an He-111.
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 V-1s into range of the Bofors guns commonly used by Allied AA units.
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.
Read more about this topic: V-1 Flying Bomb