It is fun to look at some of the old "advanced" aircraft.
However it was not always just old fashioned thinking that resisted change. And come on guys, This thing flew just 20 years after the Wright Brothers, how hidebound do we thing they were?
this was flying about 10 years earlier and the Fokker scourge was this aircraft 1915.
The Hawker Aircraft was prototype to evaluate the leading edge slat and full span flap/aileron system rather than a real fighter.
A proof of concept machine. By the time you got to a workable fighter you might have wound up with something rather different.
They had a lot of trouble with monoplanes folding up in normal fight, they also had some problems with biplanes folding up in flight.
Structure and stress was in it's infancy and there was also a difference between getting something to work as an experiment and getting it to work day in and day out, especially it stored in the open and not a hanger (or canvas tent)
Fokker had designed this to replace/supplement the D VII in 1918.
It uses a thick wing both for the air foil (many biplanes use very thin wings) and because the thick wing allows for cantilever construction without bracing wires at low weight.
That was one of the primary considerations of Early aircraft design. Can they make the plane light enough to fly using the existing engines without the structure folding up in flight.
something to think about with Hawker, how good does the forward view have to be if you are using a full span leading edge slat and a full span drooping aileron in order get lift form a 114sq ft wing? You may be coming in with nose over 10 degrees high? well over 10 degrees high?