Latécoère 501 photo from NACA-AC-170
NACA Aircraft Circular
<a rel="nofollow" class="external free" href="https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930090473.pdf">https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930090473.pdf</a>