Flak at the Mohne Dam

[garyeason]

Hi
Could some of you esteemed experts help me with a picture I'm making, please? It involves the Dambusters attack on the Mohne. I know little about Flak, but my understanding is there were six light (20mm) flak guns there: one each on the towers, one on the dam wall and three below, protecting the power station. So the question is, would these have produced only streams of tracer? What confuses me is that numerous paintings depict flak *bursts* in the sky - but I'd have thought those would come only from heavier weaponry (usually used at altitude). Does anyone know for sure? Associated question: what colour would any tracer be? - both from the flak guns and from the Lancasters' 100% .303 night tracer?

[austernj673]

I can help with the .303 tracer, when viewed at an angle and side on, the rounds tend to look like individual dots. It's only when looking from behind that you get a view of an apparent tail on the rounds. Youtube should throw up some Gulf war footage of Iraqi air defence firing tracer that will give you a better understanding.

Without the airbursts wouldn’t it be hard to portray what’s happening on canvas? Would be interesting to know if the Flak guns on the dam could depress their guns far enough to be of any use during the run in to the target as depicted during the film and in various paintings. Having walked across the Mohne there are walls either side of the walkways and I doubt that they were positioned to cover the surface of the reservoir when the aerial threat would have been perceived to have come from above. Obviously when the Bombers flew smack bang over the structure they became sitting ducks.

[Mr Merry]

It's probable that 88's were defending the dams against high level attacks as per the previous post. The 88's was able to depress low enough to fire across the water, this ability also made them a feared anti tank gun.
To defend against low level attacks they would have used 20mm Flakvierling 38's, four 20mm cannons mounted together 'vierling' meaning four. Not sure if the shells exploded if they didn't come into contact with a target though.

[garyeason]

I can help with the .303 tracer, when viewed at an angle and side on, the rounds tend to look like individual dots. It's only when looking from behind that you get a view of an apparent tail on the rounds.

I may need some artistic licence here! That said, we're talking about 100% tracer that was deliberately intended to intimidate the enemy gunners even though it was only coming from pea shooters. I've read of two of the 617 air gunners likening their own output to a "... never ending stream of fire from out of our barrels which reached out like a line from the nose to the wall like a pair of ropes on a ship to its dock".

[garyeason]

To defend against low level attacks they would have used 20mm Flakvierling 38's, four 20mm cannons mounted together 'vierling' meaning four.

Good point about the expected targets. Apparently they were single barrel 38s though, not twos or fours.

[Mr Merry]

Good point about the expected targets. Apparently they were single barrel 38s though, not twos or fours.

At that time of the war the four barrels were the norm. I stand to be corrected.

[aevans10]

Lucky enough to visit last year. Awe inspiring to think what was achieved there. Good luck with the picture.

http://www.flickr.com/photos/f22images

[whalebone]

. Not sure if the shells exploded if they didn't come into contact with a target though.

Most of the ammo types in use would self destruct due to tracer burn through according to Wikki

http://en.wikipedia.org/wiki/2_cm_Fl...8/Flakvierling

[pistonrob]

I always was under the impression that a flak shell was either time or hight fused. To get the flak to explode in such a way around an aircraft coming in at low level actually seems unlikely if you think about it. There would be no time to make the fuse adjustments.. Good for drama and effect in the movies of in paintings though.

Im sure if you read up on the many accounts from aircrew and flak stations you will quickly be able to fill in the gaps for your painting.. How far have you got with it??

[garyeason]

At that time of the war the four barrels were the norm. I stand to be corrected.

I'm sure you are right, but I'm trying to pin down a specific unit - 3. Batterie/ Leichte Flak-Abteilung 840, a unit of Flak-Regiment 124 - not the general practice. Several sources refer to single barrels. The Westphalia History portal says [Google translate from http://www.lwl.org/westfaelische-ges..._websegmente]:

"The majority of the Flakschutzes was removed already in March 1943. At the time of the attack, there were at the dam just six [2 cm] anti-aircraft guns of the 3rd Light flak battery 840, which belonged to the flak Dortmund. The solo guns had taken up position at the end of the barrier, below the dam, and on the two towers. Other protective measures, such as barrage balloons, heavy anti-aircraft batteries or concealment by artificial fog were not present."

The original of "solo guns" is "Sologeschutze" - but I'm not sure whether that means, more precisely, "single-barrelled"?

In a way what is most interesting is the picture used to accompany the text:
http://www.lwl.org/westfaelische-ges...g&bild_id=1232

- not from the Mohne, sadly, but also from a hydro-electric installation, and in 1943, and clearly intended to illustrate the sort of flak position referred to in the article.
[EDIT] Holland's well-researched recent book also refers to single-barrelled 38s.

But we know what the guns were, that wasn't my question. Which was: tracer and/or flak bursts, and what colour was the tracer?

[garyeason]

Im sure if you read up on the many accounts from aircrew and flak stations you will quickly be able to fill in the gaps for your painting.. How far have you got with it??

pistonrob: I don't paint, I work photorealistically. At the moment I have the main elements in place but need the tracer etc to bring it alive. Here's a work-in-progress draft with flak bursts - P-Popsie's starboard outer fuel tank and aileron being holed as the store was released: http://flickr.com/gp/garyeason/P5df8u

I am catching up on the personal accounts. The trouble is, everyone refers to "flak" - because they dealt with it every day, either firing it or flying through it, and they are so familiar with it they do not think to explain it. Bit like (as an example) my saying, "I filled my car up with petrol". We all know immediately what that means and can visualise the scene - but one can easily imagine, in a later era without internal combustion engines or petrol stations, sheer bafflement!

As for colour - I've just re-read Gibson's account: on his initial recce he saw three colours of tracer then in the attack says they had all become one colour (without saying which one!) Also, eye witnesses are notoriously unreliable, especially in moments of high drama and years later.

[garyeason]

Without the airbursts wouldn’t it be hard to portray what’s happening on canvas? Would be interesting to know if the Flak guns on the dam could depress their guns far enough to be of any use during the run in to the target as depicted during the film and in various paintings. ...

The guns they had could go somewhat below horizontal - and the aircrew described enemy shells skimming off the water at times (somewhat ironic if you think about it!)

[pistonrob]

Great pic. The beams of light being to one side took me by surprise as i have always thought they were angle beneath the aircraft but then that would be no use as there are no belly windows on a Lanc, save for the tiny one in the bomb bay to inspect to see if all bombs have dropped.

[garyeason]

Great pic. The beams of light being to one side took me by surprise ...

Thank you. O/T but a lot of pictures get the lights wrong but as you deduce, pointing straight down would have been little use. They were offset to starboard, the rear one also forwards, so as to form a figure of eight at 60ft that could be seen from the blister on the side of the cockpit.
http://www.rafmuseum.org.uk/research...ification.aspx

[garyeason]

So, summing up: no-one seems to know what colour the tracer was ... ?

[QldSpitty]

Trying to remember but try allied pilot reports or stories.The 20mm flak gun in a single mount was pretty standard.

[pistonrob]

By looking around at other artists work I think if you have colours fading from an light orangey yellowy white glow to the tracer you cant go wrong. light Orange for stuff closer to the viewer and greyer white for the distant tracer.. There aren`t many around who are going to question it.

I put a blow torch to a tracer 303 round many years ago and from racking my memory cells these are the colours that stood out :diablo:

[garyeason]

Ta. More reading later - summarised by this extract from a long and very detailed article by Dan Mouritzsen:
http://www.tiono.com/model/Flak-from..._viewpoint.pdf

"A 5mm-wide red, green, yellow or white band on or just above the shell's driving band on the calibres from 2cm to 4cm. The rest had a 1cm-wide band. The band reflected the shell's tracer colour. Red was the most common."

And British .303 tracer ... was likely red?

[garyeason]

Well, you can see what I finally opted for:
http://www.garyeasonphotography.com/...-the-mohne-dam

There were three 20mm guns on the dam. At the time of Martin's attack the one on the south tower had been put out of action. Or at least I think so! It might well have been his weapon exploding on the bank that dislodged it.

Thanks for all the help.

[hampden98]

My dad once dropped a naval 20mm down the chimney pipe of a room mates doorm heater. Didn't arf go bang. He got jankers for that. Interestingly it didn't do as much damage as you might expect.

[austernj673]

That looks fantastic but may I suggest a slight tweak that will add to the realism? The Brit tracer needs to be a more bright post office pinkish red looking colour, shorter tails but more in number. For the German tracer hitting the water, from previous experience tracer rounds always tend to change direction on hitting things even going through a 180 degrees and appearing to come back at the firer. A bit like emptying a bucket of water onto the floor. Probably no deflection off the water surface but very likely from the far bank of the lake.

Please don't take this as criticism, i wouldn't usually comment but it's such a great piece of work that I thought I'd try and help.

[garyeason]

... may I suggest a slight tweak that will add to the realism? ...

That is helpful, thanks. Usually in these scenes I try to work out what you would actually see. So the aircraft is doing nominally 232 mph; in my mind's eye, in the perspective of the picture, it is some 25 yards from the viewer. That's the equivalent in time of a quarter of a second. The .303s fired at about 20 rounds per second. So you'd see five or thereabouts. Someone check my reckoning - I'm probably failing to take something into account ! - but I think if anything there are too many 20mm rounds visible.

It never occurred to me to have them bouncing off the far shore - which is about 1,500 yards distant, by the way (I adhere to the idea that Gibson opted to attack straight in, over the Heversberg peninsula). None is hitting the water.

EDIT also I had the .303 tracer redder but figured they were very bright, up close (one of the issues the bomb aimers had to contend with).

[garyeason]

UPDATE: How's this?

http://flickr.com/gp/garyeason/VHz065

[Bruggen 130]

Mmm, Are the tracer rounds put in the magazines so they are in perfect synch going in to each barrel to come out side by side as in the pic?, not nit picking but it looks a bit Star Wars to me, I do like it though

[garyeason]

Are the tracer rounds put in the magazines so they are in perfect synch ...

I went to some trouble to ensure they are not in perfect synch as you can see if you look at the picture(s), though presumably each barrel would fire at approximately the same rate?

Not nit picking either but Star Wars lasers are *precisely* what tracer seems to look like up close (melding to dots further off). For example:
http://www.youtube.com/watch?v=TOlRKbWwGTo

And remember the Lancasters were using 100% tracer. I think if anything they ought to appear as almost a constant stream or "rope", as the air gunners themselves described it.

But to return to the OP, the question was: what colour? I think red - in fact I suspect red on both sides, but this is what i wanted advice on.

[Bruggen 130]

I went to some trouble to ensure they are not in perfect synch as you can see if you look at the picture(s), though presumably each barrel would fire at approximately the same rate?

But if each barrel fired at "approximately" the same rate then they would not come out in perfect synch, looking at the pic the tracer does seem to be coming out of each barrel side by side?

[garyeason]

Well it's an interesting question: if they do, is that wrong? Does anyone know the mechanical operating properties of the FN5 turret? Solenoid activation of the firing mechanism? Per gun or linked? etc...

[Smith]

I'm following this thread with fascination and I've taken a look at your website Gary. Wonderful work, I am very impressed.

But I just stopped and thought for a second - who was manning the front turrets of the Lancs? Wasn't that normally the Bomb Aimer?

Thanks, Don

[pistonrob]

In the movie they mention about the front gunners legs getting in the way by dangling down into the bomb aimers area. They devise a harness to hold the legs up and out of the way during the bomb run, so i guess there were 2 up front.

[garyeason]

... who was manning the front turrets of the Lancs? Wasn't that normally the Bomb Aimer? ...

Thank you Don. Excellent point and yes it was. But, tossing it back: what were the mid-upper gunners doing in these crews?

Interestingly in AJ-C, which was coned by searchlights and shot down (blew up in fact) on the way out near Hamm, Sgt Frank Tees had swapped places for the trip and was in the rear, not front, turret. The turret lost power when the engines were knocked out but incredibly Tees survived the fireball. He came to on the ground badly burned and became PoW. The others all died. [Sweetman's book]