Always remembered as the first of the four-engined bombers to join the RAF, the Stirling suffered from several design limitations which severely affected its performance and load-carrying capability. As a consequence, its service with Bomber Command was marred by heavy losses when used on operations alongside the higher-flying Halifaxes and Lancasters.
Air Ministry Specification B12/36, to which the Stirling was one of 11 designs proposed by various companies, called for a four-engined heavy bomber capable of carrying a bombload of 14,000lbs with a range of 3,000 miles a remarkably demanding request for the time). It also specified that the wingspan should not exceed 100 feet to enable the aircraft to fit inside current RAF hangars (although, curiously enough, the most common type of hangar, the C Type, could open to over 125 feet). As a consequence, certain aspects of the Stirling's performance suffered namely that operating altitude of the aircraft with a full load, as the wings could not generate the lift required to operate a higher altitudes.(Note this aspect--it had a major impact on the bombers performance .)