Tim Conver is retiring as AeroVironment Inc.’s chief executive next month and will be replaced by the current president and chief operating officer, Wahid Nawabi, the company announced Monday. Conver, who has served as chief executive for more than 20 years, will remain as chairman of the Simi Valley maker of unmanned aircraft and electric vehicle charging stations. Nawabi has been an integral part of AeroVironment for the past five years in supporting and building the company’s culture of innovation, Conver said. “He is uniquely capable and positioned to lead the next phase of AeroVironment’s growth for the benefit of our customers, employees and stockholders,” Conver said in a prepared statement. Nawabi joined AeroVironment in 2011 and became chief operating officer last year and named president in January. Prior to AeroVironment he worked in the industrial and electrical equipment manufacturing and clean technology industries. Conver became the company’s president in 1990 and was named as chief executive in 1992. During that period AeroVironment went from a privately held company to a publicly traded one. Shares closed down 63 cents, or 2.2 percent, to $27.44 on the Nasdaq.