When the truce to resolve World War 1 was signed, nations prepared for the next war. Fighter planes were re-built to become deadlier. It was made to fly higher, and farther more agile in combat. The planes were equipped with gun turrets, bombsights, air-cooled engines, cantilevered wings, retractable landing gear, and all new metal construction. When World War II was declared, the planes were ready. And with the US becoming a part of the war, every “first of its kind” airplane was already used for combat.
The economic depression that the world experienced in the 1920s made the military spending during peacetime look excessive.
World War I drove aviation and pilots for improvement in flying skills and technology both for civil and military. This gave the military room to develop technology for war without being noticed.
The spitfire fighter was developed from a civilian racing plane, seeing its potential for war. In 1938 for instance a Seversky pursuit plane manned by a civilian won the Bendix Race. The military saw its abilities and immediately ordered same type of planes eventually developed into Republic P-47 Thunderbolt the most preferred plane for war. Acquiring technology from civilian gave the military operational and logistical experience.
Middle of 1920s, Germans started rearmament. Lufthansa, their leading airline, was nationalized to train pilots and set the aviation industry in motion. Transformation of Luftwaffe was the highest priority since the Nazi party came to power in 1930.
All the nations started assembling their own air fleets the arms race has begun. Everyone learned from the first war the value of superior air power. This means better airplanes, top of the line, can be repaired easily and can be mass-produced. The focus was on development of fighters and bombers.
In the middle of the 1930s came all-metal monoplanes. British had two, Hawker Hurricane and Supermarine Spitfire. Machineguns installed in the wings enable the Hurricane constant firing. It had a Rolls Royce Merlin engine. Eight machineguns were installed on the Spitfire, It can fly as fast as 355 mph, and good handle at high altitudes.
The deadly Messerschmitt Me.109 can fly at speeds up to 342 mph. It can do fierce dives and quick climbs. This is Germany’s response to the Spitfire. It has the smallest possible airframe equipped with a Mercedes-Benz liquid–cooled engine.
Bombers were built with capacity for long distance travel and to carry heavy bomb loads. The technology of revolving gun turrets eliminated the need for having several guns because it can cover for the range of several. These bombers are equipped with multiple engines.
The Japanese has long-range bomber escort called Mitsubishi A6M Reisen Zero. It had great maneuverability at fast speeds and high ceiling. There is no protective armor for pilots because of the heavy weight.
The Boeing B-17 was developed in 1935. It has four engines; it has a capacity of 17,600 pounds of bombs, and 12 guns. The Boeing B-17 was planned to be the strategic bomber during the Second World War.
Hugh Trenchard of the British Royal Air Force built several bombers such as the Avro Lancaster, the Wellington, the Stirling, and the Halifax. The fighter plane for the Italians was the S.M.79 a trimotor.
By the time we had reached the year 1939, Military aviation took a big leap in technology with use of faster metal monoplanes. Germany and England is developing the jet engine.