AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE 3RD INTERNATIONAL SEMINAR ON METALLURGY AND MATERIALS (ISMM2019): Exploring New Innovation in Metallurgy and Materials - Tangerang Selatan, Indonesia (23–24 October 2019)] PROCEEDINGS OF THE 3RD INTERNATIONAL SEMINAR ON METALLURGY AND MATERIALS (ISMM2019): Exploring New Innovation in Metallurgy and Materials - Design of UAV longitudinal regulator system stability due to turbulence on cloud seeding operation: A case study of Wulung PA-07