THE AUTOQIRO PITCAIRN 269 



The Autogiro presents certain new problems with the undercar- 

 riage because of its ability to land vertically. Although the vertical 

 speed of descent in late models has been as low as 12 feet per second, 

 the condition of landing straight down requires longer travel of the 

 undercarriage with more sliock absorption than in the airplane. A 

 satisfactory arrangement is an oleo-pneumatic strut of very long 

 travel combined with the Goodyear air wheel. 



The stability of any flying machine is a matter of importance. At 

 slow speeds and particularly during vertical descent the Autogiro 

 is inherently and perfectly stable. This is because the center of 

 gravity is well behnv the rotor. The center of gravity is also slightly 

 ahead of the center of support. This provides longitudinal control 

 during vertical descent and gives the machine a marked tendency to 

 glide forward when the power is cut-olf. This insures directional 

 control and stability. Very slight forward speed is required for 

 lateral control and in vertical descent stability is so great that no 

 control is necessary even in rough weather. In fast forward speed 

 control and stability are similar to the airplane. 



In point of performance, the Autogiro offers some distinctly novel 

 experiences to the pilot accustomed to fixed-wing craft. There is 

 something fairly exciting about doing things which he has been 

 instructed to avoid at peril of accident. Such, for instance, as stop- 

 ping in the air, descending vertically, or even flying backward. 



When stopping or descending vertically the sensation, for an air- 

 plane pilot, is uncanny to say the least. He has been taught since his 

 earliest flying days not to lose his flying speed, but in the Autogiro 

 this results in nothing more than slow vertical descent. And then 

 if there is some wind and the machine is facing against it, the pilot 

 will have the outrageous sensation of flying backwards in relation to 

 the earth. 



Slow speed flying at low altitude is a most pleasant diversion, but it 

 is a sport attended in the airplane with great danger. In the 

 Autogiro, on the other hand, one can fly low and slowly at will, 

 observing at leisure the interesting features of the country. On 

 account of the slow speed he is able to turn to one side or the other 

 very quickly to avoid objects looming in his path; so in thick weather 

 he can grope his vfny along at lower altitude than the airplane and 

 also, on account of his slow speed, has time to see obstacles before 

 hitting them. If the engine stops he can get down into very small 

 spaces. 



Improvement in the Autogiro must be in the nature of evolution, 

 much as it came about in the airplane. To take a good exam[)le, our 

 first Mail wing plane, built about three years ago, had a high speed 

 of around 125 miles per iiour with 225 horsepower. Constant refine- 

 ment has increased this to 145 miles per hour. With N. A. C. A. cowl- 



