Boulton Paul P.71A photo from NACA-AC-199
NACA Aircraft Circular
1935-03-01
<a rel="nofollow" class="external free" href="https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930090515.pdf">https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930090515.pdf</a>