137503
It was delivered to the United States Army Air Corps for tests on 6 October 1934 , and after modification , including fitting with a conventional fixed undercarriage , was accepted by the Air Corps .
 United States Army Air Corps, Corps
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 United States Army Air Corps, Corps