Hi joy ride
Old photos of propellers from the not-quite-successful airplanes of people like Samuel P. Langley, Gustave Whitehead, and Hiram Maxim all show the same primitive flaring triangular shape.
The thrust of the screws, when the machine is moored, is 2,100 lb., and when it is running it is 2,000 lb.
Trial of Maxim's Steam Flying Machine
Scientific American—September 15, 1894 [From Engineering, London.]
Not bad for 1894, 2,000+ lb of thrust out of 360 h.p. is unarguably more than sufficiently effective, regardless of later improved propeller efficiency: several years before the Wrights and thus hardly "contemporary".
No comment on the "airplane" statement of faith. I think that perusal of the near 500 submissions to this thread's discussion, plus references, will give unbiased readers an opportunity to make their own minds up.