Gerard Post Herrick (1873-1955) was a lawyer and engineer who is known as the inventor of the convertible aircraft. In 1911 Herrick, a graduate of Princeton (A.B.1895) and the New York Law School (L.L.B.1897), founded the Herrick Engine Co. to market his "balanced rotary engine" concept. During World War I, he served as a captain in the Army Air Service (1918-19). After the war, Herrick developed the concept of the convertible aircraft, which could operate both as a fixed-wing airplane and as a giroplane. In late 1930, Herrick engaged F. E. Seiler, ex-chief engineer of Kellett Aircraft Corp, to assist in the design of a full-scale Vertoplane, as Herrick called his invention. After delivering a number of drawings and reports to Herrick, Seiler began work at Heath Aircraft Co. and, before his death in mid-1931, pedaled the convertible aircraft concept and the data from his work with Herrick to C. L. Stauffer, a promoter and Heath dealer. In the meantime, Ralph H. McClarren, who had met Herrick in the late 1920s at the Guggenheim School of Aeronautics and had been Seiler's assistant at Kellett, left Kellett to join Heath, where he uncovered Seiler's and Stauffer's activities.
By this time Herrick had established the Vertoplane Development Corp. of New York to finance his aircraft. Herrick contracted with Heath for the actual construction of the craft, the design of which fell to McClarren. The first aircraft, the HV-1, was ready on November 6, 1931. The test pilot, Merrill Lambert, made several successful test flights in both fixed- and rotating-wing mode, but when he attempted an in-flight transition between the two, the aircraft fell out of control and crashed. Lambert bailed out of the aircraft, but was killed when his parachute failed to open.
Post-crash analysis found no fault with the basic convertible aircraft concept and Herrick continued development work with McClarren remaining as consulting engineer. The new aircraft, the HV-2, was flight tested beginning October 31, 1936 with George Townson as test pilot. Although the aircraft flew in both fixed- and rotating-wing mode, vibrations in the rotating wing delayed the first in-flight conversion until July 30, 1937.
Herrick continued to develop the convertible airplane concept with McClarren and others, including designs with both powered and unpowered rotors, as well as a variety of configurations and power plants. In the immediate post-World War II years, he changed the company name to Convertoplane Corp. and unsuccessfully lobbied financial interests and the government for support. He remained the president of Covertoplane and stayed active in the development process until his death in 1955.