34843
At the same time , the USAF canceled the projects for their land-based high-speed interceptor aircraft , the North American XF-108 Rapier and the Lockheed YF-12 , and left the capable AIM-47 Falcon missile at a quite advanced stage of development , but with no effective launch platform .
 USAF
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 USAF