Maybe it can. I finally found someone who has spotted this parallel, straight sided thing ‘in the modern era’. https://www.google.co.uk/url?sa=t&source=web&cd=17&ved=0CCoQFjAGOApqFQoTCPnRvcGilcYCFaFp2wodLUIAzw&url=http%3A%2F%2Fcontrails.free.fr%2Ftemp%2FInverse%2520pressure%2520gradient%2520matching.pdf&ei=HaSAVbnPD6HT7QathIH4DA&usg=AFQjCNED_9aZXigA8lTXXQ2erFY0DneXvA
Buried in this article is the same re-discovery.. the author’s earliest example of this specific feature done apparently deliberately is the Bearcat (he says ‘Grumman knew something’). He can’t have noticed the Whirlwind over this side of the pond. Interestingly, it is known that Grumman did get a chance to study the one that went to the US.. but now that IS speculation!