PC/WI V-3 "Millipede" Gun used on UK ports pre OVERLORD

Without huge deep earth penetration bombs the actual launch site might have been bomb proof but not the openings for the barrels and the supply route for the prodigious numbers of shells and charges which was never going to survive allied air superiority if it ever began firing. I have wondered if one factor in going ahead with it was to make the Pas de Calais a focus for allied landings.

Re evolved long range guns. The barrel erosion by hot corrosive burning propellant is a nightmare for long term use. Even the shells have to come in gradually increasing sizes as the barrel wears. Battleship guns came with replaceable liners for just this reason but swapping liners is hard enough with conventional cannon. With a barrel hundreds of metres long it would take weeks to split the barrels back to their modular sections, extract each, remove and replace each liner then get them back into the hole they came from and fitting the sections back together. Probably easier and faster to scrap them after a while and put in new ones.

Of course there are modern practices such as base bleeding and rocket supplements but these reduce the delivered bang and increase the complexity and cost. I suspect that a very large conventional gun could be made to reach London from Calais but at a slow rate of fire. Looked at economically the V1 was the cheapest way to deliver maximum bang to a large are target. Really it only need better aiming and better mobile launchers.

Leading from the initial post. The V3 actually firing at London (somewhat ASB IMHO) would not have a major effect on Overlord but would influence decision making about either (less likely) the invasion site choice or the strategy on the ground once a viable beachhead breakout was achieved. Also it would divert both strategic and tactical air support away from OTL actions.

The basic concept is a perennial for repeated small satellite launching into low earth orbit and even smaller satellites with rocket boosting into higher orbits.
 
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Without huge deep earth penetration bombs the actual launch site might have been bomb proof but not the openings for the barrels and the supply route for the prodigious numbers of shells and charges which was never going to survive allied air superiority if it ever began firing.

I wasn't aware that Tallboy wasn't yet available but yes, the at-ground level parts of the site are vulnerable to normal bombs. And the Allies were already heavily bombing the transportation system so this would affect German installations of every type...
 
I wasn't aware that Tallboy wasn't yet available but yes, the at-ground level parts of the site are vulnerable to normal bombs. And the Allies were already heavily bombing the transportation system so this would affect German installations of every type...

Tallboy was available and they destroyed the V3 IOTL so you would need to butterfly away Tallboy/Grand Slam to get the V3 into action.
 
It should probably be noted here that there's a hell of a long way between the proof-of-concept model they built and the final "combat" model

If I recall what I've read about the project correctly, I don't think they ever perfected getting the side chambers to fire off at the right time reliably - they often fired either too late meaning that the shell had already passed or they went to early meaning they actually slowed the shell down.
 
Yes, in fact; Project Babylon was directly inspired by the V3, and some of the principles borrowed quite liberally from it - in particular, the idea of multiple propellant charges along the length of the cannon...though it's worth noting that it's not like the Nazis invented those or anything, and development in ultralong range cannons had been around since the mid-19th century.

One thing that always confused me about the V3 was - in WWI, the Paris Gun achieved ranges of over 120km with only slightly smaller shells. The distance from, say, Calais to London is under 200km. Schwerer Gustav, though it had somewhat shorter range, fired much heavier projectiles (50-100x as heavy, IIRC). So why did the the Germans go to all the trouble of multiple charges and such complex design when it seems plausible that massive but normal cannons would have worked?

Project Babylon was supposed to reach 1000km or more, but for the 180km needed, it seems more like an evolutionary solution is called for, rather than revolutionary.

I've been confused by it since I thought about a POD of building it instead of the Schwere Gustav. You figure they could only afford one set of crazy superguns. Strange that they didn't develop the Gustav design farther. The extended barrel version with rocket assisted round had a projected range of 150km. Maybe the V3 used less strategic materials in a shorter time frame.

Never thought of this before but the V3 was the worst nazi wonder weapon. Unfortunately it took the time slot of something cooler.
 
If they could have successfully built V-3s early in the Battle of Britain they might have been useful. Rather than flying aircraft over England they could just lob shells and then use their aircraft to try to stop the RAF from bombing the V-3 sites. The German pilots could then be fighting over home turf and be rescued if shot down while any British pilots would be POWs.

If they get a couple of V-3s online in 1944 their effect is going to be negligible and the sites will most likely get bombed out of commission rather quickly. Just like the rest of the wonder weapons it would be way too little way too late.
 
I've been confused by it since I thought about a POD of building it instead of the Schwere Gustav. You figure they could only afford one set of crazy superguns. Strange that they didn't develop the Gustav design farther. The extended barrel version with rocket assisted round had a projected range of 150km. Maybe the V3 used less strategic materials in a shorter time frame.

Never thought of this before but the V3 was the worst nazi wonder weapon. Unfortunately it took the time slot of something cooler.
That's far too sensible a decision for the Nazis - they practiced something very akin to social darwinism in deciding what projects succeeded or failed, but with the merits of those in charge of the project deciding success or failure rather than those of the project itself. That helps explain many dumb decisions like this - those making the decisions were often not very technically literate and were more interested in internal politics than technology in making them.
 


It would inconvenience Overlord to run it from ports in the North and West of Britain, but it could still be done. Torch and nearly all of the Pacific invasions were mounted over much greater distances.

Actually most of the US portion was run from the western ports. The assault & follow up landing force for Utah Beach came from Northern Ireland. A fair portion of the 21st AG came from London & later follow up came from ports further north. Maybe a third of the total assault force came from Channel ports.

Hastings book 'Overlord' & 'Cross Channel Attack' by Gordon & Harrison have some charts showing the embarkation ports & routes to the invasion beaches.
 
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