>>64097386
Prop planes with multiple wings have a huge amount of lift and can fly with very low horsepower. It was only briefly after humans figured out how to fly after all. The primary advantage besides being able to make them out of cloth, wood and wire was that they are extremely maneuverable. They also have very low stall speeds.
A DR.1 has a stall speed of 41 mph. That means that if it has a a 41 mph head wind it can hover. If the wind is higher it can actually fly backwards. It can actually gain altitude while flying backwards if there is enough wind. A modern aircraft carrier at full speed could fly them on a line like kites.
Early aircraft have very weird capabilities, there is this thing they can do where they can do a flat spin in a shorter distance than a modern helicopter moving at the same speed or just stop the prop and drop straight down then hope that the dive lets them kick start the engine.
>>64097431
Early engines had terrible power to weight ratios not to mention engine compression and often used total loss oil systems. Fokkers used castor oil as a lubricant that would splatter the pilots, it gave them the shits.
A modern engine with the same HP as a Fokker DR.1 weighs half as much, has a order of magnitude better fuel efficiency and twice the theoretical altitude before it chokes out due to lack of oxygen. DR/1s only had 1.5 hours of flight time, they only had 51 liters of fuel.
>>64097419
By 'still work' we are talking 30-45 seconds on a total loss engine without seizing if you got lucky, that mattered.