bids are invited for high-torque brushless dc motors - 750 kv class, suitable for 500-550 mm class airframes , electronic speed controllers esc - 30-45 a, compatible with 2-4 cell li-ion/ lipo power packs , autopilot module - pexhawk/ pix-series with completer peripheral kit (imu, i/o harness, connectors) , gps receiver module - m8-class or above with mounting bracket , rechargeable power packs - lithium polymer (lipo) 5000 mah & above, high-discharge rating , lower power distribution and monitoring unin - integrated pdb with voltage/ current telemetry & connectors , lower-range handheld radio controller - with integrated display mount and telemetry/ telecommand sp , composite propeller sets - 13-15 inch, carbon-reinforced matched paris , multi-rotor airframe kit - 500-550 mm class, modular composite structure total quantity : 18