The goal is to knock out airfields. That is a doable thing today, when almost everything needs a hard surface runway. In the early 1940s it was very difficult. Spitfires and Hurricanes had "rough field capabilities, all they needed was a few hundred yards of meadow.
The Axis had nowhere to fly FROM to achieve that short of effort. They also had no way to off load enough fuel to make it work.
Repeated for emphasis.
People need to remember that when we're talking about an "airfield" ca. 1940, that's what we mean. There isn't a fancy airbase with tarmac and a runway custom-built for specialized air traffic. There is a grass field, hopefully free of dips and holes. I have been told before but cannot confirm that later Spitfires were actually reinforced to withstand the shock of landing on concrete. Whether or not that is true, the point is that you can't take out an old airfield with a couple of good hits on the runway the way you could take out a modern airbase.
Moreover the Americans at least were widely using Marston mats, essentially interlocking steel planks, to make sort of instant-built airstrips I think starting in 1941. I don't think the British had them in 1940, but the point is, ca World War II, you can put an airfield pretty much wherever you want and repair it just as easily.
Im more asking if it were theoretically possible assuming that Germany had, at the very least, an effective design ready for production at the onset of the war, and some genuis making a convicing arguemnt for them.
Basically, i wanna know to what extent Germany can knock the RN out of the channel or the med given the aforementioned conditions which are in my mind feasible. My assumption is that the more maneuverable destroyers, which the RN had in abundance, wouldnt have much issue operating, but the heavier ships would.
Your theory is correct: if the Germans have effective anti-shipping capabilities and achieve air superiority, they can deny access to the Channel to British battleships.
The things to bear in mind however are:
1.) The British don't think they need battleships to defend against a Channel invasion anyway. Their initial plans called for intervention by destroyers and smaller ships and they expected this would be enough. I think they would panic and send everything in anyways, but when you look at the frankly haphazard German invasion "flotilla," you can definitely see why the British didn't think they would need battleships. You don't really need 15" guns to sink tugboats.
2.) If the Germans invest money in new air force capabilities, presumably the British will respond by doing likewise, and the British can probably outproduce the Germans if it comes to an arms race.
I have my doubts, the Battle of the Bismarck Sea in March 1943 was the first time air attack alone had destroyed a convoy. This battle was 114 bombers and 54 fighters against 8 transports and 8 destroyers and 100 fighters, all transports and 4 destroyers were sunk in a 3 day running battle.
If this is what it takes to sink 12 unarmoured ships with 1943 planes specifically equipped and trained to attack ships, what number of specialized planes and squadrons would be required to destroy the Home Fleet's dozens of warships in 1940? Would 500 be too many, 1500 not enough given Germany had very few torpedo bombers?
So at least half the destroyers will still be afloat after three day? Great.
I wonder how many barges the Royal Navy can sink in three days.
I am quite sure the destroyer fleet would consider the sacrifice justifiable.