Naval Aircraft Factory PN-11 / P4N
The PN-11 and P4N were efforts to achieve better perfomance by combining a more streamlined hull with the biplane wings and engines of the PN-12. The new hull was longer, deeper in profile, and approximately 30% narrower in beamm. The new hull also introduced a new empenage arrangement
featuring twin fins and rudders on top of a high mounted horizontal staliliser. In 1927 BuAer ordered two aircraft with the new hull as the PN-11, with the same takeoff power as the PN-12, and the first, powered by 525 hp Pratt & Whitney R-1690 Hornet engines, was flown in October 1928, and the second, powered by 525 hp Wright Cyclone, in June 1929. Trials indicated the the PN-11, with the same power as the PN-12, had added a 2500 lb increase in useful load that could mean a 600 mile increase in
BuAer placed an order in mid-1929 for three similar aircraft as the XP2N, but changed the designation toXP4N-1 before the fisrt were accepted in December 1930. The XP4N-1 was vertually identical to the PN-11, while the othe two, both completed in March 1932 as the XP4N-2s, carried an extra 150 USG of fuel that raised the takeoff weight by 1250 lb. Although the PN-11s and P4Ns never served operationally, the new hull became a key element of new monoplane patrol boats like the XPV/P2Y and 2M/P3M.