simplex 1 said: The propellers the Wright brothers said they had built in 1903 should have had an efficiency a bit over 75% to keep "Flyer I 1903" aloft during flight No. 4 on Dec. 17, 1903. This come in contradiction with the 66% efficient propellers the brothers claimed they had used in 1903. This is one discrepancy noticed by the team "Wright Experience"!
Another problem, I already mentioned, is that the efficiency obtained by the Wright Experience, for the alleged 1903 66% efficient propellers, varied between 75% and 82%. The team could not get that 66%.
What? If I understand you correctly, you're saying that YOU calculated from other Wright brother estimates re forward speed and RPM that the propellers needed to be 75% efficient. OK, let's accept that for a moment.
Even if it's true that the Wright brothers estimated that their propellers are 66% efficient, when in fact they were 75% efficient, why doesn't this simply suggest that they were a little off on their 66% estimate or in any one of their underlying estimates re speed or RPMs.
With all due respect, this is evidence of your current bias, not evidence of anything sinister from 110 years ago.