BoB Mathematical Modeling of Alternative Outcomes

nuuumannn said:

You'd think that Wilhelm Canaris was a British Intelligence Double Agent!

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He probably wasn't a double agent, but he was VERY anti-Nazi. From what I've read, Canaris thought the entire Nazi hierarchy was a bunch of unsophisticated clods and thugs, starting from the very top.

The idea that had the Luftwaffe been employed differently it could have won the so called " Battle of Britain " which then allows a seaborne and paratrooper invasion is a bit like saying a one armed man with a knife can defeat an man with a sub machine gun. Yes it can happen but the probability is against it. The equipment is all wrong to begin with.

At a very minimum the Luftwaffe needs drop tank capability on every Me 109 and Me 110. It needs specialised high speed reconnaissance aircraft (unarmed unarmored Me 109 maybe) to give it the intelligence that would allow it to make better decisions. Drop tanks allow the Luftwaffe to daylight escort to the shadow aircraft factories near Bristol, Birmingham, Coventry and airfields nearby. Even drop tanks on Me 109 allow these fighters over less than half of Britain. Probably the only aircraft that might have done this is the Fw 187 equipped with DB601 engines.

I believe the Luftwaffe could have stopped the Royal Navy. Land based bombers supported by land based fighters are too powerful.

Koopernic said:

I believe the Luftwaffe could have stopped the Royal Navy. Land based bombers supported by land based fighters are too powerful.

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What about at night?

PAT303 said:

What about at night?

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If Sealion happens at the planned time in late September there's 11 1/2 hours of night for the Royal Navy to come out to play. The longer the invasion goes on the less daylight.

What aircraft does the Luftwaffe have to sink capital ships, do they have big enough AP bombs and torpedoes'?.

The basic conclusion is the Luftwaffe could sink some ships, but stop the entire RN that was in British waters at the time?

Even if British ships are exposed for several hours in daylight that certainly does not mean the Luftwaffe automatically sinks them.

The Germans certainly had bombs that would work, however their standard torpedo carrier of the time was what???It was not the He 111. Germans were using Italian torpedoes?

Much is made of the Germans performance against the RN at Crete. Which was impressive but some british ships survived a number of hours of air attack. The British supply point was alexandria Egypt, hundreds of miles away. Ships in home waters can restock ammunition much easier. Ships in home waters can resupply in defended harbors/bases.
And the Luftwaffe of May 1941 was not the Luftwaffe of Sept 1940.

Some people seem to think that forcing the RAF out of south east England means that the RAF is incapable of mounting sorties (and escorting ships ) from Plymouth and/or Portsmouth in the south and from Hull or Harwich from the north.

Much of the damage would have been done by light naval forces. A flotilla of motor boats and inshore trawlers armed with a WW1 3 or 6 or 12 pounder gun a couple of WW1 machine guns and maybe a few small depth charges would cause absolute carnage amongst the river barges.

If they are amongst the invasion fleet the LW can't bomb or strafe them without killing their own men. A motorboat in the dark is virtually invisible. In daylight it will look like a German motorboat.

Koopernic said:

The idea that had the Luftwaffe been employed differently it could have won the so called " Battle of Britain " which then allows a seaborne and paratrooper invasion is a bit like saying a one armed man with a knife can defeat an man with a sub machine gun. Yes it can happen but the probability is against it. The equipment is all wrong to begin with.

At a very minimum the Luftwaffe needs drop tank capability on every Me 109 and Me 110. It needs specialised high speed reconnaissance aircraft (unarmed unarmored Me 109 maybe) to give it the intelligence that would allow it to make better decisions. Drop tanks allow the Luftwaffe to daylight escort to the shadow aircraft factories near Bristol, Birmingham, Coventry and airfields nearby. Even drop tanks on Me 109 allow these fighters over less than half of Britain. Probably the only aircraft that might have done this is the Fw 187 equipped with DB601 engines.

I believe the Luftwaffe could have stopped the Royal Navy. Land based bombers supported by land based fighters are too powerful.

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Drop tank capability allowed the Bf 109 to fight for a short time over London from the Pas de Calais, they wouldn't allow escort to Bristol or the Midlands. Twin engined fighters were poor at bomber escort, one large raid on a Birmingham factory may have had some success, it may also have been a massive wipe out, a repeat certainly would have been.

pbehn said:

Drop tank capability allowed the Bf 109 to fight for a short time over London from the Pas de Calais, they wouldn't allow escort to Bristol or the Midlands. Twin engined fighters were poor at bomber escort, one large raid on a Birmingham factory may have had some success, it may also have been a massive wipe out, a repeat certainly would have been.

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Below the distance Calais to Central London 160km/100 miles

An Me 109 at maximum cruise could fly 400 miles or 600 miles at economy cruise. Allowing 20% reserves, 100 miles for combat (probably only 50 miles at full combat power) and 20 miles for forming up leaves us an operational range radius of 100 miles.


Below the distance Calais to Birmingham/Coventry 320km 200 miles. With a drop tank adding 300L to the 400L internal fuel. We can probably operate at 320km or 200 miles from base so long as the drop tanks aren't dropped early.



As you can see the Luftwaffe stands no chance without a long range escort eg the the Fw 187 with DB601 engines.

PAT303 said:

What about at night?

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The Kriegsmarine have radar. Do the Germans need to use barges at night?

fastmongrel said:

If Sealion happens at the planned time in late September there's 11 1/2 hours of night for the Royal Navy to come out to play. The longer the invasion goes on the less daylight.

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The Kriegsmarine had Seetakt radar on all destroyers, cruisers and battleships. FuMO 22 had about 6 degrees beam width and an operator could localise a target to within 1 degree.

No enough for blind fire but enough to illuminate with star shell or a powerful searchlight. Latter versions of Seetakt (late 1940?) received lobe switching and could blind fire accurately.

The German Army could avoid using its most vulnerable vessels at night.

The German navy had fairly good night optics due to more optically clear glass and multi coat optics that minimised internal reflections in multi lens night fighting binoculars. They'd still be outnumbered by the RN.

PAT303 said:

What aircraft does the Luftwaffe have to sink capital ships, do they have big enough AP bombs and torpedoes'?.

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Good question. Its covered well on the NAVWEAPS website.

Ju 87 as dive bombers, Me 110 as slide bombers (quite accurate), Ju 88 as dive bombers and He 111 and He 115 as torpedo bombers. Do 17 as level bombers, probably throwing a stick of 4 x 250kg bombs from 1500m or so. Bombs fused for 5 second delay unless hard impact. If they hit ahead of the waterline they sink and blow up underneath causing more damage than a direct hit. The Me 109 could strafe. The British ships have very good fire control but the pom pom has bad ballistics and spoils this not solved till the boffors was used instead.

Of course by September 1940 I think the drop tank and bomb capable version of the Me 109E4B and Me 109E7B were turning up.

fastmongrel said:

Much of the damage would have been done by light naval forces. A flotilla of motor boats and inshore trawlers armed with a WW1 3 or 6 or 12 pounder gun a couple of WW1 machine guns and maybe a few small depth charges would cause absolute carnage amongst the river barges

If they are amongst the invasion fleet the LW can't bomb or strafe them without killing their own men. A motorboat in the dark is virtually invisible. In daylight it will look like a German motorboat.

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I imagine the Barges would have 1 or 2 sets of C30 or C38 20mm FLAK guns so not totally defenceless. German Torpedo Boats (about 900 tons) and e-boats would be around.

Again the Barges could avoid movement at night.

Koopernic said:

Again the Barges could avoid movement at night

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So all the waterborne movement happens in daylight, the RN gets in amongst the transports troop carriers resupply vessels, if everything gets done in the daylight hours the channel will be packed and causes havoc, aircraft are not going to do torpedo runs or drop sticks of bombs at RN ships with their own craft nearby

Where do the barges go at night. You do know that most of the barges would be unpowered and even the ones with engines could do at best 6 knots, 4 knots when towing.

Koopernic said:

The Kriegsmarine had Seetakt radar on all destroyers, cruisers and battleships. FuMO 22 had about 6 degrees beam width and an operator could localise a target to within 1 degree.

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Shortround6 said:

The German Navy is almost a non starter.
Scharnhorst (field repaired in June 1940), Field repair leaves starboard shaft out of service and some machinery still damaged. Actual repairs in dockyard took 6 months.
Admiral Scheer, Available.
Lutzow, HIt by torpedo April 11th, collapsed stern and steering gear heavily damaged. She is not recomishend until March 31st 1941,
Admiral Hipper, Available.
Prinz Eugen???? Comishend Aug 1st 1940, spends the next 6 months training and having minor improvements (main guns might not have been fired for months) Sending her into combat when only 1 1/2 to 3 months out of builders yard is suppling the RN with target
Nurnberg, Available
a dozen destroyers? maybe, depends on how the repairs to 4-5 of them are going.
20 e-boats Most of these would slightly smaller and slightly slower than the later boats. Gun armament of the early boats was one or two 20mm guns.
and 30 U-boats.

There were some other assorted small ships (900 ton steam torpedo boats, escort-sloops, steam minesweepers).

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The Germans had no battleships available, they had two heavy cruisers and 1 or two light cruisers (counting the Emden for the 2nd) and the destroyers were as described.
All of the larger ships were in German ports. Granted they do not need to be in the Channel ports days before the invasion starts but they do have to get there by the start of the actual invasion. Can the British stop all of them? no, but planning radar coverage of the invasion fleets and landing sites on ships that may or may not reach their assigned positions seems a bit slapdash, even for operation sea lion.


Some of the longer routes to planned landing beaches/sites were two days. This does not count the time needed to load and form up or the time to unload. No sea born invasion is a one shot deal, there is constant resupply. Two days each way and loading unloading times?
Given the currents, tide, and wind average speed of the barge convoys was figured to be closer to 2-3 knots.

While the luftwaffe is going after the British ships it is NOT providing support for the troops on shore who have little artillery support in the first few days (none in the first few hours) and no interdiction (stopping/slowing British reinforcements/supply of defending troops) is being performed (or very little).

No matter how good the Luftwaffe was it couldn't be everywhere doing everything that needed to be done, especially after the losses in the BoB.

Koopernic said:

gine the Barges would have 1 or 2 sets of C30 or C38 20mm FLAK guns so not totally defenceless. German Torpedo Boats (about 900 tons) and e-boats would be around.

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I imagine the germans could just conjure up several thousand C30 or C38 20mm FLAK guns that weren't being used elsewhere in a a few weeks?

The German 900 ton torpedo boats were down to a max of 8 (of the twelve built 4 were already sunk) at the end of the BoB. AS built they had two 20mm guns each. British destroyers were weak in AA but German Destroyers and steam torpedo boats in 1940 weren't much better.
British 2pder pom pom may have had poor ballistics and a poor rate of fire but at least it fired over 3 times faster than the German navies 37mm AA gun of the time (up to 30 rounds per minute per barrel, depending on crew).

Come on Sr6 don't you know that at the toot of a Nazi bugle the High Seas Fleet will rise up from the bottom of Scapa Flow where it has been rusting for 20 years and sail away to the English channel.

Snautzer01 said:

Not forgetting the chaps of the royal navy who would love the idear of blowing up floating stuff. And not only because they are good at it.

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It would be a bloodbath, as described post # 12.

The Royal Navy from its creation almost 400 years before has been waiting for this movement, to repeat the Spanish Armada and destroy another invasion attempt. The Russian winter and English Channel, two geographic hinderances the Germans never bothered to plan against.

Plus or minus losses to date and adjusting for inaccuracies, here's the fleet that's awaiting the invasion barges. This would be terrifying.

fastmongrel said:

Where do the barges go at night. You do know that most of the barges would be unpowered and even the ones with engines could do at best 6 knots, 4 knots when towing.

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The current in the channel runs at up to 6kts which is why a towed barge would struggle to land anywhere near where it aimed to and then couldn't get back to where it came from. Since the current and tide depend on the position of the Moon and Sun if you launch the invasion in the best condition then in two weeks time they are at the worst.

HMS Prince of Wales was not available at time

pbehn said:

The current in the channel runs at up to 6kts which is why a towed barge would struggle to land anywhere near where it aimed to and then couldn't get back to where it came from. Since the current and tide depend on the position of the Moon and Sun if you launch the invasion in the best condition then in two weeks time they are at the worst.

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The modern Rhine is a fast flowing river. It averages 8kmh 4.5 knots and is 10kmh 5.5 knots at its fastest point. In order for a barge to travel up river it must travel substantially faster than 5.5 knots. The 6 claimed knot maximum speed of a Rhine barge seems fishy to me as an their ability to deal with fast flowing flows and tides must be better than stated. Straightening a river increases its speed and narrows it. That makes the river less navigable in some ways and increases upward journey time. It also requires evasive maneuverability heading downstream. It may be that the 1940 Rhine was substantially slower but I think that the abominations done to it had already been done. I've seen an 1420 woodcut of a circa 200 ton medieval cog moored in Cologne 300km up stream. It had sailed there and probably been towed using tow paths at points. Europe for 1500 years from Britain, through Germany, Switzerland, Austria, Russia etc were criss crossed by thousands of kilometers of river with little canals added to the side. An Englishman should understand what the Severn could be like. They are not calm either up or down stream.

This could be in theme lecture https://www.cia.gov/library/readingroom/docs/GERMAN PLANS FOR INVASION OF ENGLAND, 1940_0001.pdf

Koopernic said:

The modern Rhine is a fast flowing river. It averages 8kmh 4.5 knots and is 10kmh 5.5 knots at its fastest point. In order for a barge to travel up river it must travel substantially faster than 5.5 knots when travelling up stream. The 6 claimed knot maximum speed of a Rhine barge seems fishy to me as an their ability to deal with fast flowing tides and points must common and is better than stated. Straightening a river increases its speed and narrows it. That makes the river less navigable in 2 ways and increases upward journey time. It may be that the 1940 Rhine was substantially slower but I think that the abominations done to it had already been done. I've seen an 1420 woodcut of a circa 200 ton medieval cog moored in Cologne 300km up stream. It had sailed there and probably been towed using tow paths. Europe for 1500 years from Britain, through Germany, Switzerland, Austria, Russia etc were cruss crossed by thousands of kilometers of river with little canals added to the side. An Englishman should understand what the Severn could be like. They are not calm either up or down stream.

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All true, but we are talking of crossing that current. I have crossed the English Channel more times than I can remember on many types of ferry. Some days and times it is like a pond completely smooth and flat and you can see the cliffs of Dover from Calais. On other days the visibility is down to 100 meters and the ferry is rising and falling at its moorings in the harbour so much they stop loading. Towing across a 6kt current is one thing when you can see where you are going, it isn't always the same current, it doesn't always flow in the same direction, any description of channel currents are very general. Dover was never "blacked out" when I crossed the channel but frequently you didn't see it until a couple of miles away either by day or night and I once spent 4 hours stuck in the channel waiting for the fog to clear in daytime. Hitler and some of his followers made a big mistake thinking it is just a big river crossing. it just isn't for many reasons, I have been on two ferries that were swept into the harbour wall going out of Dover, if you look at a modern ferry doing the route they all have massive reinforcement around the water line because it happens quite often going in, going out and while mooring.