Doubly so when you consider the supersonic barrier.
Air drag is proportional to the drag-coefficient * velocity^2. So doubling your speed quadruples the drag.
Except... the drag-coefficient itself is a complex curve over velocity. It barely changes from 0mph through 300mph, but once you reach transonic and supersonic speeds, the drag-coefficient skyrockets.
As a result: 250mph is more than 4x more efficient than 500mph from a drag perspective (4x predicted from Drag equation, but in practice might be 8x or more). This is mostly a problem for airplane efficiency and fuel consumption, but I'm sure it applies to war-machines and projectiles too.
--------
But modern airplanes fly at very high heights, so the air is thinner, reducing drag, but requiring a pressurized cabin lest everyone gets hypoxia.
Tell that to cyclists :-) You can barely go above 25 km/h (~15 mph) without feeling like you are just pedaling to overcome the drag.
Reducing the Cd on a bike, ie going recumbent and putting a aerodynamic shell on it, ie switching to a velomobile allows you to go 40 km/h (~25 mph) with relative ease.
Just in case you misunderstood the parent post -- your Cd as a cyclist is pretty much constant around your normal cycling speeds. Your total air drag goes up with the square of velocity, that's for sure, but if you went transsonic on your bike, your Cd would ALSO increase dramatically on top of the already brutal velocity-squared multiplier.
It’s almost worse, because you’re working against this quadratic force, at a rate proportional to speed. So power output, the usual limiting factor for a cyclist, scales like 3rd power of speed.
Air drag is proportional to the drag-coefficient * velocity^2. So doubling your speed quadruples the drag.
Except... the drag-coefficient itself is a complex curve over velocity. It barely changes from 0mph through 300mph, but once you reach transonic and supersonic speeds, the drag-coefficient skyrockets.
As a result: 250mph is more than 4x more efficient than 500mph from a drag perspective (4x predicted from Drag equation, but in practice might be 8x or more). This is mostly a problem for airplane efficiency and fuel consumption, but I'm sure it applies to war-machines and projectiles too.
--------
But modern airplanes fly at very high heights, so the air is thinner, reducing drag, but requiring a pressurized cabin lest everyone gets hypoxia.