370462
Design considerations Angular momentum One of the problems with any single set of rotor blades is the tendency of the helicopter body to begin spinning in the opposite direction to that of the rotors once airborne .
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Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities:  
Answer:
 None