TLS, two pages, 8.5 x 11, The Wright Company letterhead, November 10, 1911. Letter to Lieutenant H. H. Arnold. In full: “Your letter of recent date seems to have disappeared and it is possible that it is lying at Kitty Hawk. I am answering the main points of the letter as I remember them.
The screws on the ‘B’ machine should run inside a closed shed 425 turns per minute. With an old motor in good condition they have been run more than 440 turns per minute. If the result is below 410 the motor is palpably in need of attention. Each five turns per minute indicates a difference of one horse power, but as the screws may vary a trifle after they have been out a while, a variation of five is not abnormal. The motors gain in power as they become older if well cared for, the gain at the end of the year being about three horse power. It is very important that the motor should never be run without plenty of water in the radiator, and oil in the tank. If the motor overheats the cylinders warp a trifle and a month may elapse before the motor again comes up to the old mark. Mr. Coffyn at Detroit recently carried three men and a set of hydroplanes, a total load of more than 600 lbs. above weight of machine. If you will time the motor or screws indoors and give us the result of the test last preceding the time when the water begins to boil, we can tell you whether or not the motor is allright. Always stop as soon as the water begins to boil. It is best to repeat the test several times to make sure of the results. It is very important in a new motor that the spark should not be advanced more than three inches as measured on the fly wheel. On an old motor three and one half inches is all right.
The propellers and chains have a large factor of safety and if the sudden jerks are avoided, will easily carry 25% more power than our present motors give.
I do not remember any other points upon which you wished information, but we are always pleased to have you ask for any needed information and to have you tell us from time to time what things about the machine you find unsatisfactory, or capable of being changed to afford better satisfaction.”
Intersecting folds, two through single letters of signature, uniform toning to both pages, some light soiling to edges of first page, and a few creases and wrinkles, otherwise fine condition.
In this remarkable correspondence, Wright provides detailed information on the Wright Model B Flyer, an early biplane designed by the Wright brothers in the United States in 1910. Wright carefully and explicitly explains his aircraft, including such minutia as “the screws on the ‘B’ machine should run inside a closed shed 425 turns per minute,” normal and abnormal behavior of the engine, weight limits, and the observation that “if the motor overheats the cylinders warp a trifle and a month may elapse before the motor again comes up to the old mark.” His words provide a remarkable explanation of early flight. The Wright B Flyer was eventually used to provide pilot training and reconnaissance for the US Army Signal Corps between 1911 and 1914. During this period, the Wright Company trained 115 pilots, several of whom went on to greater fame including the recipient of this letter, Henry ‘Hap’ Arnold, who at the time was assigned to a winter flying school in Augusta, Georgia. He would later write of his days as a young lieutenant and meeting Wilbur Wright. Focused on becoming an ordinance officer, Arnold was approached by a superior officer and asked if he was interested in training as a pilot. ‘In the third week of April 1911, I found myself on a train bound from New York to Dayton,’ Arnold wrote. His first flight on May 3, 1911, lasted seven minutes, with his instructor’s first remark on the flight described as ‘rough.’ A highly desirable artifact linking one of the Army’s greatest pilots and Wilbur Wright, who would die from typhoid fever six months later. Pre-certified John Reznikoff/PSA/DNA and RR Auction COA.
Terms and abbreviations used in our descriptions.