Authie et Mi

Rediscovering the V1

November 2021

Searching for a on a map

By 1942 the Allies were aware that the Germans were in the process of developing some sort of flying bomb but they had no idea as to where, or what form, exactly, it took.

This mystical terror weapon would turn out to be the V2 rocket, being developed at Peenemünde, on an island off the German Baltic coast. This was of course unknown to the Allies who had simply received intelligence suggesting that something was going on at the site.

Photographic missions were sent on a regular basis in an effort to spot something out of the ordinary. A hard task when you have no idea what that something is supposed to be. Eventually though one of the Photographic Interpreters (PI) spotted that a round object on the ground, in one frame, had a sizeable shadow in another.

The new weapon wasn’t a cannon or an aircraft : it was a rocket ; launched vertically.

To complicate matters however, in the autumn of 1943, just as the scientists and PIs were getting their heads around what the rocket might or might not be capable of, and much more importantly, when it would be ready, reports of other launches from Peenemünde were coming in. These were definitely not a rocket. The trajectory and speeds were simply not sufficient enough.

Piecing together clues from a rash of new building sites, across the northern French coastline, alongside details from intercepted Luftwaffe messages the conclusion was drawn that this new weapon was indeed a flying bomb. More worryingly, the rapid construction of dozens of sites suggested that it was at a far more advanced stage of development than the rocket.

The aerial photos of Peenemünde were once again scrutinised, but this time looking for something that ought to have wings and be about the size of a small aircraft (otherwise it wouldn’t fit in the buildings being constructed in France). There it was, a tiny † near a hangar.

This flying bomb, the Fiesler Fi 103, is better known as the V-1 and the letter V is for Vergeltungswaffe the German for vengeance weapon.

My father who witnessed them during the blitz describes it as a flying blow-lamp and he is not so far out. The fuselage was constructed of sheet steel, the wings were often simple plywood and it carried an 850 kg warhead. The jet engine pulsed fifty times per second giving it a characteristic buzzing sound which Londoners soon nicknamed the Buzz Bomb.

Once spotted, the tiny missile began being identified in other, higher definition photographs. These photos were sometimes taken from a height of 7,000 metres and as the V1 only has a wing span of about five metres they were incredibly difficult to spot.

Engineers and scientists were given what little information was to hand along with the approximate dimensions of the craft. It was calculated that such a machine could not take off under its own power and that some sort of launch ramp, with a catapult, would be needed to hurl it out in the right direction, with enough velocity, to allow the on-board engine to take over and keep it in flight. Militarily it was probably the first Cruise Missile.

Weeks of pouring over photos began to confirm that not only were there ramps at the Peenemünde test site but the newly formed ski sites in France were also equipped with them. With nearly a hundred such sites along the coast and each one appearing to be able to stock twenty missiles the new threat was taken very seriously.

There was still uncertainty as to just how the V1 was launched. There were no signs of any catapult machinery in the photos or being reported in intelligence but what could be seen were skid marks beyond the ramps. The experts’ final assessment was (correctly) that the missile was launched from a simple trolley which ran up the ramp and then fell off into the field.

This observation would prove to be important later on, as the V1 launch sites became increasingly harder to pinpoint — observers could look for the tell-tale holes in the ground.

The Ski launch sites

Whilst that original hunt for details on the the new weapons was underway on the Baltic coast, reports drifted in from France that construction companies were being hired to create some new facilities near Abbeville.

As the initial discovery had been a rocket it was considered essential that some sort of rail network would be needed to bring them to the launch sites. The new constructions, however, rarely had any such facilities.

Fortunately the French firms carrying out the work were not making any efforts to conceal their labours and following intelligence reports concerning work in the Bois Carré near Yvrench (Just outside Crécy) No 170 Squadron RAF flew a reconnaissance sortie E/463 on 3rd November 1943.

Yvrench Bois Carre in November 1943

Yvrench Bois Carré on 3rd November 1943 : Photo from NCAP

What really caught the Photo Interpreter’s eye were the odd shaped buildings that looked like skis, on their sides, out in the open fields, as well as a ramp with surrounding blast walls.

The description of Bois Carré was given to all of the construction sites with a similar layout. You will also see them referred to as ski-sites after the shape of the storage buildings.

Yvrench Bois Carre in April 1944

Yvrench Bois Carré in April 1944 : Photo from NCAP

Once it was realised that one of the features of these sites was the three ski bunkers they became readily identifiable. Another marker was a specific building in exact alignment with the ramp, both of which were aligned towards London.

By early November dozens of similar sites had been plotted. Photographic sorties continued along the entire coast and ninety-six ski-sites were identified, but to what purpose ? The ski bunkers were too narrow to take a rocket and the shallow curve at the end (giving them their name) would not be negotiable by anything of size.

Weeks later the V1 would be identified and the entire system began to fall into place. One query had always been as to why two of the ski bunkers were about eighty metres long but the other was only seventy. The answer would turn out to be simplicity itself : the firing capacity of each site was calculated to be twenty and twenty doesn’t divide by three !

By December 1943 the Allies were clear that they were about to be faced by two new weapons : a flying bomb and a rocket. Whilst the latter was the greater menace (due to its payload and speed) the former posed the more imminent threat.

Intelligence reports, as well as intercepted Luftwaffe messages, all provided information as to how the V1 actually worked as well as its working range.

The guidance system was very simple, based around a gyrocompass, stabilisers and a fixed amount of fuel. The catapult sent the V-1 off in the required general direction and the gyrocompass then took over, the stabilisers kept it flying level and when the fuel ran out, it dropped.

People realised that as long as the buzzing continued it meant that the rocket was flying overhead and there was no danger, but as soon as the engine stopped the bomb was activated.

To help conceal its purpose the V-1 was officially named as an anti-aircraft apparatus (FZG) and the regiment of the Luftwaffe created to use them was designated Flakregiment 155 (W). Flak is the abbreviation for an anti-aircraft gun and thus the reason for allied pilots having to: Take Flak.

The V-1 rockets were built by Volkswagen at their factory near Hamburg.

The German military hierarchy had differing ideas as to how to launch their new weapon. Huge bunkers (which would draw attention to themselves) or smaller, less obvious sites. In the end Göring made the decision to build 4 large bunkers (Wasserwerken — waterworks) and 96 smaller bases. 64 of these bases were to be constructed by October 1943 whilst the remainder would be held in reserve.

A control centre was based at Creil near Paris but the idea of moving it to the Citadel at Doullens, where the telephone exchange was already based, was later considered.

The Tödt Organisation used 40,000 workers in northern France to build the bases. Nobody was allowed to work in their own village, so although a base was built at for example Ligescourt (near the Crécy battlefield of 1346), drafted workers from the village would have been sent elsewhere.

Even though they were adapted to the local situation the bases followed a very similar design allowing missiles to be brought in, stocked, prepared and launched on a conveyor belt system, moving from one building to another as parts were added and calibrated before finally reaching the ramp and sent on their journey.

If the team was well trained it was reckoned that it would take about thirty minutes to receive the missile, prepare it and have it on its way to London.

The base needed to be on flat land and small woods were considered to be the ideal location.

The linking roadways between the bunkers were created using concrete slabs and the buildings for the most part were constructed with breeze blocks, which dispensed with the need to provide a casing for poured concrete.

The problem for the Germans was the shape of the storage buildings. As has been seen, their particular shape made the sites stand out and they were very soon located.

Posted : 13 May 2022

House, Coast