You can also increase speed by not using any propellers or moving parts. At supersonic speeds you capture the air, compress it into a chamber than hit it with a spark and blow the fucker up. That’s how a ramjet engine works. China just made one that uses pulse like combustions in a engine that’s only about a foot wide, and maybe 13 feet long. Speeds up to mach 4… or 5000km/h (3100mph) at about 65,000 feet.
Yeah i didn’t catch that, thanks