346 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1961 



Excellent cooperation was obtained from every organization and 

 individual with whom we worked. Among them were the Pioneer 

 Instrmnent Co., the Radio Corp. of America, and the Bell Telephone 

 Laboratories, which installed the modern radio transmitter and pro- 

 vided miniature earphones with molded plugs. Along with the other 

 BTL personnel, Capt. Luff Meridith and Capt. Ray Books, recently 

 retired from the Army Air Corps, were very helpful. At the Aircraft 

 Radio Corp. of Radio Frequency Laboratories, which installed the 

 excellent radio receiver. Dr. L. M. PIull, the president; Drs. A. W. 

 Parkes, F. H, Drake, and all members of the staff were most coopera- 

 tive. Assistance was also rendered by the Kollsman Instrmnent Co., 

 the Sperry Gyroscope Co., and many other industrial concerns, scien- 

 tists, engineers, and inventors. Very valuable support was received 

 from the Bureau of Standards, whose experts designed and installed 

 most of the ground and airborne radio navigation equipment. Dr. 

 Harry Diamond, of the Bureau, and his associates spent much time 

 with us and could not have been more cooperative. 



"Wliile aural signals were satisfactory for rough aerial navigation, 

 it soon became apparent that a visual indicator would be much better 

 for the precise directional control required in blind landings. To 

 meet this requirement, the Bureau of Standards, working with the 

 Airways and Radio Division of the Department of Commerce, de- 

 signed a 2-kw. semiportable two-leg range, which was used as a hom- 

 ing beacon, and a fan-type marker beacon. The homing range was 

 installed on the west side of Mitchel Field. The marker beacon sat 

 on the leg of the homing range and was located on the east side of 

 the field. 



The indicator for the homing range, carried in the airplane, was a 

 pair of juxtaposed vibrating reeds. If the plane was to the right of 

 the course, the right reed vibrated through the greater amplitude; 

 if to the left of the course, the left reed vibrated more vigorously. 

 If the plane was on course, both reeds vibrated through the same arc. 

 As the station was approached, if the amplitude of vibration became 

 too great, it could be reduced through use of a rheostat. 



As the fan-type marker beacon was approached, a single reed started 

 to vibrate. It reached maximum amplitude, then quickly dropped to 

 zero when the airplane was directly overhead, rapidly built up to 

 maximum again, and then tapered down. The homing-range indi- 

 cator also had a distinct null when the airplane Avas directly over the 

 range station. 



As the tests progressed, the instrumentation and equipment were 

 constantly improved until toward the end of 1929, during the final 

 stages of the flight tests, the following instruments and equipment 

 were carried : 



