an improvised bomb sight that was lined up with the long axis of his aircraft, loaded a bomb in a canvas mail bag that was attached to the JN-4's belly, and launched a single-handed raid at treetop level, in support of a USMC unit that had been trapped by Haitian Cacos rebels. Although the JN-4 almost disintegrated in the pullout, the attack was effective and led to Sanderson in 1920 developing further dive-bombing techniques to provide Marine pilots with close aerial support to infantry comrades. Variants Although the first series of JN-4s were virtually identical to the JN-3, the JN-4 series was based on production orders from 1915 to 1919. JN-1 — possibly unofficial designation of the second Model J, which served as the prototype for the Model JN. JN-1W — Two aircraft that appear in US Navy records, which may have been confused with the Model S-4 and S-5. JN-2 — first production version, 8 built JN-3 — variant with new unequal-span wings and improved flight controls, 97 built for the RNAS (some sources indicate 91, but serial numbers total 97; 12 built in Canada) plus 2 for the US Army. The six surviving JN-2s were modified to this standard. JN-4A — production version of the JN-4, 781 built JN-4B — This version was powered by an OX-2 piston engine; 76 were built for the US Army, and nine for the US Navy. JN-4C — experimental version, only two were built JN-4 (Canadian) Canuck — Canadian-built version, 1,260 built by Canadian Aeroplanes Ltd. for the RFC in Canada/RAF in Canada and USAAC: Independently derived from the JN-3, it had a lighter airframe, ailerons on both wings, a bigger and more rounded rudder, and differently shaped wings, stabilizer, and elevators. Its use by the USAAC was curtailed as the lighter structure was claimed to cause more accidents than the US-built aircraft, although no air fatalities were attributed to the structural integrity of the type. JN-4D — improved version, adopting the control stick from the JN-4 (Canadian) 2,812 built JN-4D-2 — One prototype only, the engine mount was revised to eliminate the down thrust position. JN-4H — two-seat advanced trainer biplane with ailerons on both wings, 929 built for the US Army, notable for introducing the use of the Wright Aeronautical license-built Hispano-Suiza 8 V-8 engine for greater power and reliability JN-4HT — two-seat, dual-control trainer version JN-4HB — bombing trainer