Authie et Mi

Rediscovering the V1

November 2021

Searching for a dot on a photo

By 1942 the Allies were aware that the Germans were in the process of developing some sort of flying bomb. This mystical terror weapon was in fact the V2 rocket, being developed at Peenemünde on an island off the German Baltic coast.

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 technicians 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 aircraft : it was a rocket, launched vertically.

To complicate matters, however, in the autumn of 1943, just as the scientists and photographic interpreters were getting their heads around what the rocket might or might not be capable of, and much more important, 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, crossed shaped dot near a hangar.

This flying bomb, the Fiesler Fi 103, is better known as the V-1. Its description Vergeltungswaffe is 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.

hrule.

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, did not have those 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.

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.

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, all 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 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, had been 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.

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.

Crossbow

Photographic evidence of the various sites gave the Allies a good idea as to how the construction work on the various was sites was progressing and this suggested that the Germans would be in a position to begin launching the V1 within a matter of months — possibly even weeks from some of the sites.

Operation Crossbow was set up to bomb the Bois Carré sites concentrating on those at the most advanced stage of construction.

These missions were named, “No-Ball Missions”, and the very first was launched against the installations at Ligescourt by B-26 bombers of the USAF on 5th December 1943. To be honest, when you look at the condition of the buildings at the site today you can see that apart from one of the ski structures they pretty much missed their target.

Bomber bait

In effect, with very few exceptions, none of these bases ever got to be used because they were just too obvious and ended up drawing the RAF and USAF bombers onto them. This eventually became an advantage to the Germans who ensured that the French workers were occupied in repairing the sites.

As for the massive Wasserwerk bunkers, they were found to have structural flaws and couldn’t be used anyway, but of course the Allies didn’t know that.

My elderly neighbours would say that the RAF became so tunnel-visioned about Ligescourt that they missed the light launch site on the other side of the village, a few kilometres away.

By the middle of March 1944 over half the sites had been severely damaged and the Germans seemed to have given up on constant repair work. Where it did occur the work concentrated on the ramp and the building aligned to it. That building was clearly important but the connection between it, the V1 and the launch ramp had yet to be made.

The light ramp launch sites

The allies continued with their aerial coverage constantly on the lookout for repair work on the previously targeted sites and the construction of new ones. Operation Overlord, the Normandy landings, was just weeks away and the new missiles could pose a serious threat to not just London but also England’s southern ports, where troops and equipment were being concentrated in readiness for the beginning of June.

Suddenly a new form of site was discovered at Belhamelin near Cherbourg, right opposite the gathering stations for the invasion of France. This new lighter site was given the name of the village to differentiate it from the Bois Carré sites.

In order to resolve the problem of the high visibility of the larger complexes the German command ordered the creation of lighter launch sites with fewer bunkers and a basic ramp. These were quicker to build and much more easily repaired. The Germans only used slave labour and German engineers to carry out the work which allowed for greater secrecy.

These modified sites were much more discreet in their construction and were only identified for what they were days before the V-1 blitz on London began on 13th June 1944.

With the first of these new Belhamelin sites all being found along the Normandy coast and aligned not on London but the ports of Bristol and Portsmouth a new flurry of overflights had to be carried out. This meant flying and photographing the entire coastal area within about 250 kilometres of London or Portsmouth and then scrutinising each frame trying to spot a ramp or its accompanying building.

It was clear from Belhamelin that much of the infrastructure that made the original sites to identifiable, despite the Germans’ best efforts of camouflage and use of the terrain, was not applicable to the new sites.

As Overlord approached aerial reconnaissance was required for it and the work on finding the new sites became increasingly difficult without up-to-date coverage. Without the ski-bunkers a new signature was needed and this was found in the foundations for the ramp and the prefabricated aligned building.

As luck would have it, coverage of the Luftwaffe’s training base on the Baltic coast revealed a Belhamelin site under construction. Sections of rail and the parts for the building were brought in and a site could be up and running in forty-eight hours !

The period immediately prior to 6th June (D-Day) saw as many of the new sites bombed as possible but they were far harder to hit and took bombers away from other essential tasks. The weather was not great (D-Day itself was delayed by twenty-four hours because of it) so photographic missions were curtailed for a while.

Then on 11th June a mission showed that some sites had been fully installed. The calculation had been that forty-eight hours would be sufficient for the site to begin launching and the first batch were indeed launched on the night of the 12th/13th June. It wasn’t an auspicious start with only four of the ten missiles making it to England.

A sigh of relief could be heard in London : the terror weapon was a failure.

Four nights later, having reviewed their methods, the Germans launched a larger salvo and seventy-three bombs hit London. During the Blitz Londoners had became used to the bombing but each V-1 carried a warhead equivalent to five Heinkel He 111 bombers (a cross between weight and the far more efficient explosive).

Between 13th June 1944 and 29th March 1945 about 10,000 were fired at England ; 2,419 reached London, killing about 6,184 people and injuring 17,981. All in all some 30,000 V-1s were manufactured.

Unlike the previous Blitz the V-1 allowed for no pauses. They could arrive during broad daylight as easily as night. Heavy cloud cover brought no respite as the pilotless aircraft didn’t need to see its target. It simply flew until its fuel ran out. Those below could only hope that the buzzing passed overhead and on towards somebody else.

One of the ways of limiting the destruction of London was by falsely reporting the strikes. By stating that the outer suburbs on the far side had been bombed instead of the centre, the launch teams reduced the fuel, causing short falls. This may well have limited the damage to the capital but the bombs still fell on somebody.

Eventually though the Germans got crafty and began equipping some of the missiles with transmitters that their own radar systems could track.

As the Allies advanced out of Normandy the Germans were forced to give up launch sites and so a newer form of site began appearing. This consisted pretty much of just a ramp and the firing bunker.

I have a couple of such sites near to the house and up in the woods at the top of the hill is a large concrete platform originally intended for the V-2 rocket. By the time the first of those had been fired at London (from the Netherlands) on 8th September 1944 the village had been liberated and the pad now serves as a storage point for cut wood.

=

There were certain similarities between the bases through necessity of preparation. There were bunkers to store the chemicals for the catapult (hydrogen peroxide and potassium permanganate) and an anti-magnetic building constructed without any iron in it at all.

This was the last building that the rocket passed through before launch and it was here that the magnetic compass would be set. The entire flight depended on the compass working properly and so any possible interference had to be avoided at this stage.

The one building that seems to have been augmented was the firing bunker which now offered the firing crew a better field of vision and better protection.


Posted : 13 May 2022

House, Coast