First operational US helicopter - notably used during WWII in India/Burma by the 1st Air Commando Group (Project 9) for medivac and rescue of downed aviators. Six prototypes were delivered, two were lost during operations. For a short read about this unit see
http://www.airforcehistory.hq.af.mil...onThursday.pdf .
Build is stock (1:48 scale by printing the large Army version at 50%) with the substitution of fine copper wire for extra card layers to stiffen the rotor blades. Picture above has the blades rotating the wrong direction - a bit of confusion with the instruction sheet drawings, 3-view and photos showing different arrangements. Fortunately, the rotor disk is not glued down so a quick flip will set things to right.
Yogi