Complex sentence: Bristol had already studied a large bomber design starting as early as 1937, and then the Air Ministry published a tender for a new super-heavy bomber design in 1942 they dusted off their original work and updated it for their newer and much more powerful Bristol Centaurus engines.
Split into simpler sentences: Bristol had already studied a large bomber design starting as early as 1937, and then the Air Ministry published a tender for a new super-heavy bomber design. In 1942 they dusted off their original work and updated it for their newer and much more powerful Bristol Centaurus engines.