This is a creation for a World War 1 challenge.

Fictional history:

The Chollima Heavy Bomber was introduced towards the very end of World War 1, first seeing action in August 1918. It was designed for the task of carrying a heavy bomb load over a long distance, a task it performed well by the standards of the time. Powered by four engines arranged as two push-pull propeller units and with a large fuel tank carried in the fuselage, the Chollima was able to carry 2500 lbs of bombs at over 100 mph and at heights of 13000 feet. This combination of height and speed made it hard to intercept, negating the disadvantage of the lack of defensive weapons, while the large operating range made it hard to predict which targets the Chollima squadron would attack.
Pilots liked flying the Chollima, it had good stability in the air and could manoeuvre fairly well for such a large plane. They also enjoyed the comfort of the fully enclosed cockpit; this was unusual at the time, but the combination of long flights and high altitude made it necessary to protect the aircrew from the elements if they were to be of any use at the end of the flight. The standard crew was four - two pilots, a bombardier and a navigator / engineer.
After the war ended, some examples of the Chollima were converted into small airliners, but the production run had been too small for them to see widespread use. Some were retained by the military for use as patrol and observation planes, making use of the long endurance. The most famous examples were used for public relations purposes. The sturdy undercarriage made the plane well suited to pioneering flights, and for some time it was not unusual for the first flight to an area to have been performed by a Chollima. Some of these were aviation pioneers, seeking to make a name for themselves, while some were government efforts, showing the flag in distant colonies.