Why were so many WWI aircraft made from wood and biplanes? A few monoplanes existed but they were rare
They didn’t have powerful enough engines to get a heavier, metal plane off the ground.
…and biplanes were stronger, since they could have additional bracing outside the wings and fuselage. Shorter wings overall made better maneuverability as well.
Once metal and internal skeletons came into the picture, the advantages of biplanes mostly went away.
Wood is easier to work with, and can be lighter than metal. Remember that these airplanes had heavy engines of 100 to 150 hp.
As I understand it, the biplane format was chosen because they were believed to be more maneuverable than monoplanes. At the time, a lot of emphasis was put on manuverability. In practice, many if not most kills were by ambush where attacking aircraft would dive through a formation. I think the emphasis on maneuverability is why they had such aircraft as the Fokker DR.1, which had three sets of wings and was short coupled.
As has been noted metal was heavy and engines of the time were weak.
The reason for a bi-plane was a wooden wing was not strong enough to handle the rigors of flying if it were a single wing. The wing would snap since it had to be longer than two short wings to provide sufficient lift.
So the solution is shorter wings and put two (or more) of them on the plane.
Once engines became more powerful and metal could be used the disadvantages of the bi-plane (mainly drag) were not worth continuing. Less drag means faster planes and that trumps maneuverability in this case.
Yes, speed lets you dictate the engagement, among other things. = life.
Better rate of climb, too.
“Ja… bot dis fokker vas flyink ein Messerschmitt!”
One thing that hasn’t been brought up is the airfoils used were very thin. This was thought to be required for low drag. A thin wing doesn’t have enough spar depth for a cantilever wing, so it had to be externally braced. Even the monoplanes had bracing struts or wires. If you’re going to have all those wires out there anyway, getting extra wing area is a good value.
It wasn’t until the 1920s that 12% thick airfoils were shown to have lower drag.
There’s a famous story about this, in which Orville Wright proved (to some young’un that later became an aircraft designer) that thin airfoils were better than thick by showing him the drag readings in a scale wind tunnel. He was correct.
It wasn’t until the sections were tested at something like full scale (instead of model scale) that the reverse was proven.
Actually the Fokker D.VII introduced thick airfoil technology (to call it something) into the fighter arena sometime during '17, it was a biplane and had one N shaped interplane strut, but allegedly that was more about reassuring pilots than an actual structural necessity.
The next in line, the Fokker D.VIII had a single, cantilevered parasol wing (mounted on struts above the fuselage).
All that was based on previous work by Junkers, he was crazy enough to build an all metal (and steel at that!) cantilever wing monoplane back in '15 that actually worked quite decently, but I guess it was too far ahead at the time for the technology to enter mainstream manufacturing and in any case heavy airplanes like that could not match the climb and maneuverability of wood and canvas fighters of the time.
There was a (wrong) belief in British flying circles that monoplanes were inherently unsafe.
Rigidity. It was much, much easier to make a strong, rigid wing with a biplane. The dual wings wired and strutted together are like a girder. All the strength for a single wing has to be contained inside it, which required stronger materials (i.e. aluminum) and more complex engineering.
They didn’t just stop at biplanes.
See the Caponi Ca 60 – triplane wings, and 3 sets of them – a 9-winger (novoplane?).
