Hi</p>

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A good example of density altitude was the experience of the Wright Brothers at SIMMS Station in Ohio in the spring of 1904 and the problems they had getting the 1904 Flyer to fly. This is from a interesting book:</p>

"Kill Devil Hill Discovering the secret of the Wright Brothers" by Harry Combs and Martin Caidin. The following is from pages 238 to 240.</p>

1. On December 17, 1903 at Kitty Hawk the temperature was 34 degres F. at first time flight which produced a density altitude of 1800 feet below sea level. THe wind was also high at 27 MPH so they were able to take off with a short track as they did not have to make a long run to acelerate the plane to flying speed. Ideal flying conditions.</p>

2. The following spring at SIMMS Station in Ohio in May 1904, May 23 @ 81 degres F they struggled to take off and were not able toget the 1904 Flyer airborne because the density altitude was 2900 feet above sea level . At SIMMS Station at a stardard day, the density altitide is 815 feet. THey had alsoreduced the wing camber which reduced lift. They were not able to fly, other than short hops, thru the summer.</p>

3. As the temperature dropped later in the fall they had much better success but the main reason was that in September 1904 they constructed a catalput that gave the airplane enough acceleration to get airborne on the track as power was marginal. As the air cooled in the Autumn the flights became longer. THeir longest flight in 1904 was on December 1, which lasted 5 minutes and 8 seconds.</p>

Cheers</p>

Ray</p>