68413
Two airframes were built , with one intended for static testing , the low-wing cantilever monoplane was of mixed construction with a one-piece two-spar wooden wing , tapering in chord and thickness , covered with plywood forward of the mainspar and the under sides with fabric covering the rest .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 None