One of the political consequences of the Treaty of Versailles, which ended the First World War, was the imposition of severe restrictions on Germany's military/industrial complex. As a result, much of the research and development that went into the He111 was conducted under the guise of civilian aviation. The project began at the behest of the Air Ministry well before the existence of the Luftwaffe was ever officially admitted. The He111 was theoretically developed as a fast commercial transport, but eventually it became one of the mainstays of the German bomber force early in the war.
The He111 adopted the Junkers Jumo engine in 1939 and fully 400 of the early variants of this airframe were in service in time for the invasion of Poland. The Heinkel is certainly not as famous as the Ju87 Stuka dive bomber from this campaign, but it caused considerable damage nonetheless. The He111 played a significant role in the conquest of France as well, but in each instance the bomber operated in an environment of almost complete German air superiority. This would not be the case in the Battle of Britain, and the shortcomings of the He111 soon became painfully apparent against RAF Hurricanes and Spitfires.
Germany fielded more than ten variants of this airframe over the course of the war, and produced 7450 planes for frontline service, but none of them were capable of successful combat operations independent of heavy fighter escort in contested airspace. The reasons for this are numerous. First and foremost, the top end speed of the fully loaded bomber was barely over 200 mph. and it took 50 minutes to climb to a cruising altitude of 4500 meters (approximately 15,000 feet). Because enemy fighters enjoyed a 50-100% speed advantage, their pilots could engage, break off and reposition for the next attack fairly rapidly. Also, since the fighter's relative speed in relation to the He111 was so high, it was difficult for the bomber's gunners to line up a successful deflection shot.
Wingspan: 74 ft. 1 in.
Length: 53 ft. 9 in.
Height: 13 ft. 1 in.
Engine: 2 x Junkers Jumo 211A-3 rated 1,100 hp.
Loaded Weight: 30,860 lb.
Maximum Speed: 252 mph.
Service Ceiling: 26,300 ft.
Combat Radius: 640 miles
Armaments: 4,000 lbs. of bombs, 6 x 7.92mm machine guns
Defensive Fire Arc: