As work proceeded, it was agreed to cut down the number of pulse jet motors from two to one, and since Argus were not specialists in airframe construction the assistance of Robert Lusser, technical director at Heinkel, was brought in. In June 1942 General-Fieldmarshal Erhard Milch gave the authorization of the Ministry for development to proceed as a top priority and in secret. By the end of that year an unpowered version was already being flight-tested. The jet has to fly at a minimum speed of 150mph (240km/h) to maintain operation. Launching was done by flooding the tube with acetylene and setting fire to it from an external battery. The whole craft was then launched from a ramp and — once at speed — it just kept flying. The ramps were powered by hydrogen peroxide (T-Stoff) and potassium permanganate (Z-Stoff) which generated a burst of gas that accelerated the bomb to a launch speed of 360mph (580km/h).
Once aloft, the V-1, as the missile was commonly known, was guided by a simple autopilot invented by the Askania Company in Berlin. An inertial pendulum was attached to a stabilized gyrocompass and the flaps were controlled by compressed air from two large round tanks pressurized to 150atm (15,000kPa) prior to the launch. The same pressure was also used to feed the fuel into the motor. The early V-1 missiles sent towards London were fitted with small radio transmitters to allow their progress to be monitored. A small propeller on the nose of the craft was fixed to an odometer which counted the revolutions — every 30 rotations of the propeller caused the counter to go down by 1. The initial setting was made to match the distance that the pilotless plane was intended to fly; when it had counted down to zero it was above the destination and had reached the planned target. At this point explosive bolts fired within the control mechanism and the V-1 was set to dive into the target. Many people have thought that the odometer shut off the fuel supply, as the V-1 fell silent as it began to fall. That’s not the case — the silence was due to the fact that the sudden drop in the nose prevented the fuel from getting through. The type of V-1 flown later in the war had this fault corrected, so the motor continued to run until the craft hit the ground.
And so the buzz-bomb entered the annals of secret weapons history. The Fieseler Fi-103 V-1 was a flying bomb weighing 4,750lb (2,150kg) and measuring 27ft 3¾in (8.32m) long, 17ft 6in (5.37m) wide from wing tip to wing tip and just 4ft 8in (1.42m) tall. It carried 1,870lb (850kg) of the explosive Amatol-39 and was powered by an Argus As 109–014 pulse jet over a maximum range of 150 miles (250km) and an operating speed of 400mph (640km/h) at an altitude between 2,000 and 3,000ft (600–900m). The buzz-bomb was one of the crudest, cheapest and simplest secret weapons ever developed — and yet it remains one of the best known.
This was Hitler’s first weapon of retaliation, and was also the world’s first successful cruise missile. Known in full to the Germans as the Vergeltungswaffe-1, and nicknamed by the British ‘the doodlebug’, it was designed at Peenemünde by the Luftwaffe during World War II as a terror weapon with which to attack major cities — the principal target being London. The very first V-1 was launched towards London on 13 June 1944 and hit a railway bridge on Grove Road, Mile End, killing eight residents. It was just one week after the Allied landings had begun on the Normandy beaches. Within a month, more than 100 of the V-1 weapons were being dispatched to rain down on London every day. Roughly 30,000 V-1s were manufactured, each taking 350 man-hours and costing 4 per cent as much as a V-2 rocket. Altogether 9,521 doodlebugs landed in Britain before the launch site was occupied by the Allies in October 1944. The remaining weapons available to the Germans were then trained on Antwerp, which received 2,448 attacks until March 1945 when the Allies captured the final launch ramp. The V-1s killed a total of 22,892 people and almost every one of them was a civilian. This was a sustained terror bombing, a cruel and vindictive campaign against a defiant enemy.
Amazingly, a piloted version of the primitive V-1 was flown and several leading test pilots were killed while attempting to land because they could not adapt to the high stall speed. The most successful German test pilot during World War II was a former medical student, Hanna Reitsch, who was awarded the Iron Cross First Class. She was the first-ever female test pilot and made test flights later in the war, successfully landing in the V-1 several times. Because Germans were prohibited for many years from flying powered aircraft, Reitsch turned to gliding after the war, and some of her records remain unbroken to this day.
Hanna Reitsch was interrogated by American Intelligence officers as the war ended and she told them that she wished to kneel down in reverence at the Führer’s bunker and her dearest wish would have been to die with Hitler. She remained loyal to Nazi ideals to her death in 1979. An American journalist, Ron Laytner, was the last to interview her and quotes her as saying: ‘Our great army has gone soft. Soldiers wear beards and question orders. I am not ashamed to say I believed in National Socialism… Many Germans feel guilty. But they don’t explain the real guilt we share — that we lost the war.’
Despite the advanced technology, there were problems with the V-1s that couldn’t have been foreseen. A German pilot recalled the problems they came up against:
Because there were no launch sites left in France and Belgium, the V-1 rockets were struggling to reach central London, so in October [1944] we began to fly with them. The main problem with them was the wind. If we didn’t judge the wind right we missed London. Also, many of our V-1s got shot down by English flak. We had to climb to 500 metres before we could let go of the V-1, that is if the English fighters didn’t get us first… By the time the V-1 came in, we still had a little hope that we could win the war, but not much, as the Allied air power was so superior.
Ernst Eberling, Imperial War Museum Sound 11389
As the numbers of V-1s over England increased, the RAF pilots sought alternative methods to deal with them, rather than relying on anti-aircraft fire. Of the first 144 missiles that reached the coast in the first V-1 attack, seven were downed by British fighter pilots. The Hawker Tempest was discovered to be the best aircraft for shooting down the rockets due to its speed and 20mm cannon, but by late June pilots discovered that they could also ‘tip’ the V-1 over by flying alongside and banking their aircraft — the missile could not cope with the change of direction, and so would fall to the ground. Squadron Leader Berry was the most successful at downing a doodlebug, claiming 60 V-1 rockets:
There is a new kind of battle going on in the skies over London — Spitfires versus the German Flying Bombs… Mind you, I can say from personal experience that the Doodle Bug doesn’t go down easily… You have to aim at the propulsion unit — that’s the long stove-pipe, as we call it, on the tail. If your range and aim are dead on, you can see pieces flying off the stove-pip. The big white flame at the end goes out, and down goes the bomb.
Squadron Leader Joseph Berry, BBC radio interview
The British were at a loss as to how to defend themselves against the relentless attacks. They began to use barrage balloons that were large hydrogen-filled blimps, such as those discussed earlier in this book, with lines of steel cables hanging down in a long array. These were intended to intercept flying bombs as they approached, but the leading edge of the V-1 was able to cut the cables and only about 300 buzz-bombs were claimed to have been brought down by the barrage balloons. The Allies also began to use simple analogue computers to calculate the aim of anti-aircraft guns in June 1944. Just 17 per cent of the flying bombs were brought down by gunfire during their first week on the south coast, but with the assistance of the simple computers this rose to 60 per cent by 23 August and 74 per cent by the end of that month. On the best day, 82 per cent of the V-1s launched were destroyed by Allied guns.