222 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1950 



The most notable features of this machine are quite well known. 

 Briefly, they are : 



1. Flight range increased to 24 miles. 



2. Endurance increased to over 38 minutes. 



3. Catapult used for launching. 



4. Rudder operated independently. It was concurrent with, al- 

 though not attributable to, this change that the Wrights learned to 

 avoid stalls in the turn by careful use of the elevator instead of trying 

 to correct entirely with the rudder. 



PREPARING FOR THE FIRST SALE IN 1908 



The years 1906 and 1907 were devoted to intense developing and 

 testing of an airplane that would be of practical value to the United 

 States Army. In 1908 the final form of this machine w^as successfully 

 demonstrated by Orville to carry two occupants over a closed 125-mile 

 course at a speed of 42 miles per hour. 



In this machine, a new vertical engine was used to provide space for 

 the extra passenger. The hip yoke for the wing warp was replaced 

 by a hand lever, both occupants now sitting upright. The rudder con- 

 trol was not interconnected. 



The engine was now equipped with four 4%- by 4i/4-inch cylinders, 

 developing a maximum total of 39 hoursepower at 1,600 revolutions 

 per minute. The water jacket was no longer cast integral with the 

 cranl^case, there being individual thin-walled castings around each 

 of the cylinders. There was still no water cooling of the heads. Igni- 

 tion for starting and running was furnished by a "Mea" magneto 

 through high-tension cable to single spark plugs. Both the magneto 

 and the camshaft were gear-driven. 



There were two gear pumps driven by the camshaft, the first an oil 

 pump furnishing lubricant to the main bearings and the second a fuel 

 pump. Each connecting rod had a small, drilled finger scoop for its 

 lubrication. The engine was stopped by the compression release de- 

 vice used in the 1904—05 engine. An intake manifold with internal 

 baffling conducted the fuel mixture to each cylinder. Fuel was intro- 

 duced through a small jet orifice into an open air-intake tube leading 

 into the center of the intake manifold. 



CONCLUDING REMARKS 



In a paper of this length it is impossible to cover all the many 

 incidents of historical interest, the lack, it is hoped, being compen- 

 sated for by a more complete recording of the steps taken to develop 

 one of our greatest inventions from first conception to a "reduction 

 to practice" salable machine. 



