What did the Atlas have for engines before the RD-180? Weren’t they American built?
What happened?
The Atlas II launch vehicle used RS-56 engines, which topped out at 207,000 lbf of thrust.
The RD-180 makes 860,000 lbf plus of thrust in a package that’s only slightly larger.
The proposed replacements from American companies will produce 500,000-550,000 at best.
The Russians simply made (and make) more powerful liquid-fueled engines, partially because their solid-fuel rocket tech was pretty bad. US rocket development was crippled by Clinton’s Peace Dividend and environmental laws that simply made it too expensive for many to develop new engines.