Herrick made the "Balanced Rotary Engine" with documents deposited in the Nasm (BH-492000-01).

From Appendix 11: We have found more information through the NASM.

-Gerard Post Herrick (1873-1955) was a lawyer and engineer who is known to be the inventor of the convertible airplane. He founded Herrick Engine Co to commercialize his Balanced Rotary Engine.