Wheelock received his commission as a Second Lieutenant in the United States Army from West Point in May 1983. He entered the U.S. Army Aviation School, Fort Rucker, Alabama in 1984 and graduated at the top of his flight class and was designated as an Army Aviator in September 1984. Subsequently served as a combat aviation Section Leader, Platoon Leader, Company Executive Officer, Battalion Operations Officer, and Air Cavalry Troop Commander in the Pacific Theater (Hawaii, Korea and the Philippines). Following a successful command, he was assigned to the Aviation Directorate of Combat Developments, Fort Rucker, Alabama, as a Research and Development Staff Engineer. He earned a Master of Science degree in Aerospace Engineering from the Georgia Institute of Technology in 1992, having completed graduate studies and independent research in the areas of hypersonic and high temperature gas dynamics, flight stability and control, and automatic control and robotics. He was selected as a member of Class 104 at the U.S. Naval Test Pilot School and upon completion was assigned as an Experimental Test Pilot with the U.S. Army Aviation Technical Test Center (ATTC). With ATTC, his flight testing was focused in the areas of tactical reconnaissance and surveillance systems in the OH-58D(I), RU-21H and C-23. His tour with ATTC culminated with his assignment as Division Chief for fixed wing testing of airborne signal and imagery intelligence systems in support of the National Program Office for Intelligence and Electronic Warfare. He is also a graduate of the Army Airborne and Air Assault Courses, the Aviation Advanced Course, the Material Acquisition Management Course, and the U.S. Army Command and General Staff College.
A dual rated Senior Army Aviator; he has logged over 2000 flight hours in 43 different rotary and fixed wing aircraft.