The development of the Avro Manchester (and then Lancaster) was a bit of a mess. The first Manchester prototype flew just five weeks before WW2 started, and mi

The development of the Avro Manchester (and then Lancaster) was a bit of a mess. The first Manchester prototype flew just five weeks before WW2 started, and might have been rushed into production. But there were major flaws with the reliability and power of the engines, and Avro were already working on the Lancaster to replace the Manchester before the first production models even entered service. The Lancaster is simply a Manchester, with the two Rolls-Royce Vulture engines replaced by four Merlin engines.