What is the level of air vehicle performance needed to replace ground vehicles?

[shin_getter]

Flying is simply superior to ground movement if excluding its costs. Faster speed, greater degree of freedom.

It is easy to think that flying can never be superior to ground movement in some niches, but it really depends on performance and cost. Just consider the other type of fluid on earth, there are a lot of submarines (basically: blimps) but almost no seabed-crawlers. I suppose the same can be true for dense atmosphere low gravity moons elsewhere in this solar system.

The extremely conservative view of flying is that, flying can replace ground movement if it can do everything ground movement is capable of, in terms of payload_weight*speed/cost, vehicle_size/payload, detectable_energy_emissions/(payload*velocity) and other characteristics. This is overly conservative however since basic advantages of flight is ignored here.

Instead, performance requirements can be discussed for different niches. The thing to follow next is whether technology is closing or separating performance curves for ground and aerial movement to figure out the trend for the future.

So what is needed for flying things to be better than pushing on solid soil?

 

[Scott Kenny]

Primarily, the ability to avoid each other with minimal external input. True autonomous flight. "User"/passenger punches in their destination on the phone app and the aircraft does all the work.

eVTOLs may be able to work tolerably well for short hops and maybe half an hour between uses.

 

[Dilandu]

The main problem of flying is that it's very costly, especially in terms of energy - and dangerous in terms of breakown. Sure, it's possible to make a flying truck - but it would be a fuel hog, and economically unsustainable. And if something would broke down, the ground truck would most likely merely stop. The flying one would fell down (depending on design, more or less controllably), which is dangerous for both the driver(s) and the ones below.

 

[Dilandu]

Just consider the other type of fluid on earth, there are a lot of submarines (basically: blimps) but almost no seabed-crawlers

There are MUCH more surface ships, that submarines. And the absolute majority of submarines in the world are purely military, with a small number of scientific and recreational ones.

The seabed crawlers did not became popular due to the simple reason; pressure increase rapidly with depth, so it's much simpler to float on water, than trying to survive on the bottom. Not to mention, that the average "terrain" of seabed is rather poorly suited for movement. It's quite rugged, with a lot of untraversable features like canyons, mountains, reefs, ect. Sure, you could always use buoyancy to just jump over... but then why bother with crawling?