He graduated from Massachusetts Institute of Technology (MIT) with a Bachelor of Science degree in mechanical engineering in June 1928, and stayed to teach and conduct research work in the aeronautics department.

As stipulated by Harry Guggenheim, Kelsey flew as Lieutenant Jimmy Doolittle's safety pilot during the first fully 'blind' instrument flight on September 24, 1929, showing observers that he was not in control by keeping his hands visible outside the cockpit.

[3] The following year he graduated from Primary and Advanced Flying Schools, and in 1931 he obtained his Master of Science degree in aeronautical engineering at MIT.

[1] In 1934, Kelsey was transferred to Materiel Command at Wright Field near Dayton, Ohio, and served as fighter project officer in the Engineering Section.

[6] Kelsey became frustrated by inflexible Air Corps restrictions on pursuit (fighter) aircraft which limited the weight of all guns and ammunition to 500 lbs.

Kelsey specified Allison V-1710 engines with General Electric turbo-superchargers and tricycle landing gear in both proposals, aiming for 360-mile-per-hour (580 km/h) performance, long range, the ability to climb to 20,000 feet (6,100 m) in six minutes, and very heavy armament including a cannon.

After the prototype flew, Kelsey was called to England, and handed oversight of the project off to colleagues who, in keeping with advice from the National Advisory Committee for Aeronautics (NACA), ordered the removal of turbo-superchargers from the aircraft.

[8] After Lockheed performed a series of tests and associated engineering adjustments, Kelsey took the prototype across the country on a record-breaking speed flight in February 1939.

Just short of his goal, as he was directed into the landing pattern at Mitchel Field behind three slow trainer aircraft, his prototype's carburetors iced up and the engines would not respond—they continued to idle and would not increase in power.

[12] Without the ability to add power, Kelsey fell short of the runway and belly-landed into a sand trap at a golf course, destroying the plane but suffering only minor scratches himself.

Kelsey applied full rudder and aileron at the same time, and suddenly the aircraft lost one wing and the whole tail, and entered an inverted flat spin.

[17] He formulated the specifications for the Curtiss XP-46 and placed an order for two prototypes in September 1939, hoping that the advanced aircraft would replace the P-40 Warhawk which had not demonstrated above-average fighting qualities.

Production of the new design was canceled by General Henry "Hap" Arnold as it was anticipated that a four-month delay in Curtiss fighter deliveries would be incurred by the radical change.

Kelsey's boss, Colonel Oliver P. Echols, shopped the design to the Anglo-French Purchasing Commission who were told to find an aircraft manufacturer that wasn't busy with war production.

Kelsey clarified and expedited the communication of battlefield requests back to the NAA production team such that the turnaround time of modifications was minimized.

[19] From May to July 1940 Kelsey was sent as assistant military attache for air to Europe to assess the technical progress of German, French and British fighter aircraft.

[20] In England, Kelsey determined that the threat posed to Allied convoys by German air and naval power meant that an aerial ferry route should be established over the North Atlantic so that long-range aircraft could be flown to the United Kingdom rather than shipped.

While Spaatz and Hunter remained in England, Kelsey helped a group of war refugees travel to the United States,[20] returning himself to Wright Field as chief of the Pursuit Branch in the Production Engineering Section.

[22] One famous example of these drop tanks was in Operation Vengeance, April 1943, when P-38Gs needed extra range to intercept and kill Admiral Isoroku Yamamoto.

In the spring of 1942 Kelsey was attached to the VIII Fighter Command at Dow Field near Bangor, Maine, to assist in preparing for trans-Atlantic ferry flights in support of Operation Bolero.

[24] Kelsey brought to the project the extensive support of the Air Force Flight Test Center, and began to shop the proposal around the industry.

He invited 12 aviation contractors with prior fighter aircraft experience to bid on the project: Bell, Boeing, Chance-Vought, Consolidated (Convair), Douglas, Grumman, Lockheed, Martin, McDonnell, NAA, Northrop and Republic.

[28] In carrying out the duties of the award, Kelsey appeared in March 1960 at MIT, the University of Maryland, College Park and in Los Angeles[29] to give a talk about the factors which determine the optimum size of aircraft.

Tony LeVier, Kelly Johnson and some Lightning aces shared a panel discussion with him, and Kelsey participated in interviews recalling the history of fighter development in World War II.

[31] As the occupant of the Charles A. Lindbergh Chair in Aerospace History[32] at the National Air and Space Museum, Kelsey wrote an overview of American aircraft development before and during World War II.

Kelsey compared this careful husbanding of the potential for war-making effort with the myth of Cadmus, a Phoenician prince who supposedly sowed dragon's teeth in the ground to create an instant army.