2618
At the engine intake , cold air from the boundary layer below the main inlet enters the fuselage ( boundary layer suction , first tested on the Northrop X-21 ) and is mixed with hot exhaust air just before the nozzles ( similar to the Ryan AQM-91 Firefly ) .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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