Originally Posted by
43Inches
The physics is what makes shipping so costly, you are pushing through water the weight of the ship, water also limits the top speed without costing too much fuel. Hence Hydrofoils and Ekranoplans were concepts that are still being looked at today, although other issues come up when you try and fly multi thousand tons at low level at high speed. Hydrofoils and Early Ekranoplans lack the the clearance to operate over rough oceanic areas, the KM while it had a payload of 100 tons it could only fly at 10-20 meters due to its short wingspan, limiting it to relatively flat water areas. At the moment another Russian company is developing a freight Ekranoplan with payload of about 60-80 tons, this one has larger span to operate over oceanic areas.
As far as the physics prohibiting super large aircraft, that is only a limitation of current technology. We also have to remember that ships were limited in size until the 1800s when metallurgy advances allowed the construction on larger hulls and propulsion systems. When the SS Great Britain was floated out of dock in 1845 it was larger than any other ship by 30 mtrs at only 98 mtrs long, and 1000 tons heavier at 3500 ton. Now there are ships over 400 mts and 600,000 tons just over 150 years later. Likewise aircraft are still in development, we might have some stagnation now, but there's still a lot of technology that can be applied. Not saying they will ever reach the carrying ability of the super ships but they definitely can get a lot bigger.
Whether you are travelling through water or travelling through air, the basic four forces still apply: thrust, drag, lift/buoyancy, and weight. Archimedes gets his lift (buoyancy) vector essentially for free; simply create the hull shape that generates excess displacement and you're done. Bernoulli only gets his lift vector by applying work (airflow) to an aerofoil; simply creating the appropriate wing doesn't give you lift unless you can get air flowing over it - that means thrust is required. It is the fundamental physics of the medium you are working in.
Ships scale quite easily; aircraft do not. Take a 250,000 tonnes payload; modest by shipping standards. Work out what wing area and how much thrust you would need to lift that. If you could get it to work, it will not be more efficient than a ship.
Unless you want to apply magic to the problem, it is simply impractical. And that's not even factoring in some other basic practical considerations such as undercarriage design, runway and pavement strengths, etc