CH-4 UCAV made its first flight with a Heavy oil engine (probably a DB416 "Skylark" engine from Anhui Airlines X Aviation Power Equipment Co Ltd) Shi Wen (UAV Chief engineer) explained it will increase its range of operations by 30-50%

CCTV informed yesterday that the 🇨🇳CH-4 UCAV made its first flight with a Heavy oil engine (probably a DB416 "Skylark" engine from Anhui Airlines X Aviation Power Equipment Co Ltd)

Shi Wen (UAV Chief engineer) explained it will increase its range of operations by 30-50% pic.twitter.com/yzFD0KXV5V

— Jesus Roman (@jesusfroman) August 18, 2022

An increase that great just by going to heavy oil? Didn't know that was a thing. If so then why hasn't it been done before?