This is the .50 Brushless Electric Motor from O.S. Motors.

FEATURES: For airplanes using a .50 size 2-stroke engine or 4-stroke .91 size
            engine
          Centrifugal fan design with angled ventilation holes draws air
            through the motor and across the windings and magnets for improved
            cooling

INCLUDES: .50 Brushless Electric Motor with Backplate, four Phillips Head
            Mounting Screws, 4mm Gold Plated Male Plugs attached to leads,
            three 4mm Female Plugs with Shrink Wrap, Prop Adapter and
            Instruction Sheet

REQUIRES: 90A brushless ESC

SPECS:    Rated Power: 1550W
          Rated Voltage: 25.9 - 29.6V
          Rated Current: 50 - 60A
          Maximum Current (10 sec): 90A
          No Load Current: 2.0A
          Phase Resistance: 27.5 miliohms
          Maximum Efficiency: 85%
          kV: 375
          Poles: 14
          Shaft Diameter: 0.23" (6mm)
          Shaft Length: 0.45" (11.5mm)
          Weight: 14.3oz (405g)
          Lead Wire Length: 4.3" (110mm)
          Length of Motor Can to Backplate: 2.3" (57.5mm)
          Diameter of Motor Can: 1.98" (50mm)
          Length/rear of Motor Can to Prop Washer: 2.9" (74mm)
          Prop Washer Diameter: 1.06" (27mm)
          Thickness of Motor Mount: 0.16" (4mm)
          Width of Motor Mount: 2.67" (68mm)
          Height of Motor Mount: 2.67" (68mm)

          Performance for this motor with different props and LiPo cells is as
            follows (all data with 100A ESC):
          Prop Size              Max Electric Current      LiPo Cells
          14 x 8                       45A                     8S
          14 x 10                      56A                     8S
          15 x 8E                      50A                     8S
          15 x 8E                      38A                     7S
          16 x 8E                      62A                     8S
          16 x 8E                      47A                     7S
          15 x 10E                     60A                     8S
          15 x 10E                     47A                     7S
          16 x 10E                     57A                     7S
          16 x 10E                     43A                     6S

COMMENTS: Nomenclature is defined as follows:
            0MA means 0.S. airplane motor
            First two digits are the rotor diameter
            Second two digits are the length of the magnets
            Last digits indicate the kV of the motor

                                                                   jxs 05/11/11
                                                                         ir/jxs