I read once that in WWII, Germany’s next “big weapon” was the V3, which was going to be a long-range cannon. Apparently, it never got off the ground, and was nothing more than a pipe dream–but what was the point, when the V1’s and V2’s were raining down rather easily on hapless Britain? A big gun like that would seem to carry a lot more potential problems than the “fire-and-forget” V1 and V2 weapons.
Here’s an interesting link about the V3:
http://www.theotherside.co.uk/tm-heritage/visit/visit-2caps-mimoyec-v3.htm
I don’t think the V2 was as an effective weapon as you make it out to be. The V2 was never anything more than a weapon of terror, not a strategic weapon. Liquid fueled rockets were a very new art in those days and I imagine that the success ratio could not have been better than 25%. We were still blowing up missiles on the launch pad with regularity well into the 1960’s. They were also probably frighteningly expensive, since when they did fail on the launch pad I imagine the repair job took weeks at a time with all that high exposive tucked into the nosecone.
V1’s could be detected by the British radar nets and could be knocked out of the sky by fighter planes and we never that great of a weapon.
Now a good old fashioned giant cannon was an improvement over the V2 because it was comfortable '40s technology scaled up to a new level. It likely would have been fairly reliable, much more aimable, and able to barrage the target area, rather than hope for one lucky shot. Thankfully Hitler never got the chance to try.
The Germans had all sorts of weird and wonderful ideas for long-range bombardment (in fact, I believe that the First World War’s Paris Gun is the first time that anything was fired into space (or near as dammit).
We should be thankful that the Nazi regime fostered so much internal rivalry, duplication of effort and interservice bad blood: chasing so many different ideas used up brains and gold that could have been put in pursuit of one or two big projects that might have caused a great deal more grief for the Allies.
The V3 gun was a multichambered weapon, built in a huge underground complex built at horrific expense in France (by slave labour, IIRC?). It had been noted by Allied intelligence, and was heavily bombed before it could come into action: in fact, it was this target that Joseph Kennedy, Jr. was on the way to attack when he was killed.
It does seem like a waste of effort, with the serviceable V-1 and V-2 weapons hitting Britain (and targets like Antwerp and Liege, in Belgium). The V2, although a technical marvel, and the first ICBM (or CBM, at at least), was far too expensive for the damage it did: IIRC, nearly 20 V-1s could have been built for the expense of a single V-2. On the other hand, it gave no warning of arrival, and could not be shot down (as many of the V-1s were).
Imagine if all the time, effort and money producing this white elephant had been freed up to build more V2s, or even King Tigers or Type XXIII U-boats; it wouldn’t have won the war for Germany, but quite likely prolonged things, and cost more lives on both sides.
The V3 site at Mimoyecques in France still exists, although it is badly damaged rubble for the most part.