The alleged Thrust/HP obtained by the Wright brothers in 1903 is enormous, well above what Hiram Maxim obtained in 1894
Hiram Maxim 1894
- Power delivered to the propellers = 363 HP
- Propellers thrust = 2000 - 2100 lb
Thrust/Power = 2000 to 2100 lb / 363 HP = 5.51 to 5.78 lb/HP
Wright brothers 1903
- Engine power (we do not know how much of it was delivered to the propellers) = 12 - 16 HP
- Propellers thrust = 132 - 136 lb
Thrust/Power = 132 to 136 lb / 12 to 16 HP = 8.25 to 11.33 lb/HP
From 5.78 lb/HP, the best thrust obtained by Hiram Maxim, to 8.25 lb/HP, the worst of the 1903 Wrights' flyer, there is an increase of 42%, which is enormous and comes out of nothing because the two brothers have never had a convincing story about what exactly they did to improve the thrust of their propellers to such incredible levels for 1903.
1)
"The actual horse power delivered to the screws is 363 when the engines are running at 375 revolutions per minute. Of this, we are informed by Mr. Maxim, 150 horse power are expended in slip, 133 horse power in actual lift on the aeroplanes, and 80 horse power in driving the machine, with its frames and wires, through the air. The thrust of the screws, when the machine is moored, is 2,100 lb., and when it is running it is 2,000 lb. We give these figures as they were supplied to us, omitting decimals. The total lift is something over 10,000 lb. at a speed of forty miles an hour and with the aeroplanes making an angle of about 7.25 degrees with the horizontal."
Source: Scientific American-September 15, 1894 [From Engineering, London.],
http://www.456fis.org/THE_HISTORY_OF...IRAM_MAXIM.htm
2)
"By early fall (1903), they had built the propellers that would carry them aloft. The Wright brothers did not have the instrumentation to measure actual propeller performance in flight. However, the Wright notebooks contain static thrust measurements recorded for the actual propeller pair (on Nov. 21, 28, and Dec. 17, 1903). To make these measurements, the Wrights placed the Flyer in a shed and perched it on its launch carriage. They restrained one of the lower wing tips and attached the other wing tip to a line. That line connected to "50 pounds of sand" and then to a grocer's scale, letting the brothers measure the restraining force while the machine was powered in the shed. Since the Wright Flyer had no throttle, the engine speed could not be controlled, but the notebook entries indicate that the average measured static thrust was between 132 and 136 pounds (that is, each propeller produced a thrust of between 66 and 68 pounds) when the propellers were powered at a nominal rotational speed of 350 rpm."
Source:
Mechanical Engineering "100 Years of Flight" supplement, Dec. 2003 -- "Prop-Wrights," Feature Article