EARLY INSTRUMENT FLYING DOOLITTLE 347 



1. Normal engine instruments. 



2. Magnetic compass. 



3. Earth inductor compass. 



4. Bank-and-turn indicator. 



5. Directional gyro. 



6. Artificial horizon. 



7. Airspeed indicator. 



8. Altimeter. 



9. Rate-of-climb indicator. 



10. Outside air thermometer. 



11. Vibrating reed homing range indicator. 



12. Vibrating reed marker beacon indicator. 



Considerable thought was given to the location or arrangement of 

 each instrument in order to facilitate reading and reduce pilot fatigue. 

 Fatigue led to errors, and piloting errors could not be tolerated in 

 instrument landings. The airplane, in addition to its flight instru- 

 ments, carried a KFL radio receiver, a BTL radio transmitter, two 

 6-inch Pyle National landing lights, and a parachute flare. Small 

 instruments were preferred over the more conventional larger ones 

 because, even though they were somewhat harder to read individually, 

 the small mstruments permitted more compact and logical arrange- 

 ment and were easier to read and interpret en masse. It was soon 

 determined that small instruments could be made easier to read by 

 use of broader hands with white or radium paint applied to the outer 

 half of their length. It was fomid that the instruments could be read 

 more quickly, and over a long period with less fatigue, if the arrange- 

 ment of the instruments and the position and direction of motion of 

 the indicating hands was "natural." Also any abnormality or im- 

 proper indication should be detectable automatically by a quick glance 

 at the instrument panel. This did not "solve" instrument flight but 

 did simplify it. 



A larger than customary Leece-Neville generator was installed on 

 the engine to assure an adequate and continuous electrical supply. 

 The mast-type receiving antenna, which was employed to minimize 

 directional effect, required considerable development before a tendency 

 to vibrate under certain flight conditions could be corrected. A trail- 

 ing wire antenna was used for transmission in normal flight. This 

 was reeled in and a fixed wire antenna used for transmitting when 

 landmg. 



The specialized ground equipment consisted of a radio receiver 

 and transmitter which provided voice communication with the air- 

 craft and a Kollsman sensitive altimeter with which the altimeter in 

 the airplane was synchronized by radio. In addition, there was the 

 visual homing range and the visual fan-type marker beacon previously 

 mentioned, and, of course, there was available the standard Mitchel 



