The Bird Dog is essentially a Cessna 170 with tandem seating for pilot and observer. First lights were in 1949 with the designation L-19 (for liaison). Name switched in 1962 to the O-1 for Observation. Depending on the livery used an L-19 or O-1 may be built. With a wing span of 36ft. the BMJR kit at 40.5” is a scale of 1 .125” / Ft. The kit is offered in 2 versions “dihedral” wing (Park Flyer) and “aileron” wing (Sport Scale). Dihedral is for rudder ,elevator and motor. The aileron wing has rudder, elevator, motor, ailerons and FLAPS. With 200 Watt electric power our “dihedral” model came in at 18.5 oz. and our aileron wing with “FLAPS” came in at 20.25 oz.