Developer of the first practical American helicopter. TLS signed “I. I. Sikorsky,” one page, 8.5 x 11, Vought-Sikorsky Aircraft letterhead, April 27, 1942. Sikorsky apprises George Grebenstchikoff of his company’s expansion and a current literary project, in part: “Our work here is progressing as usual, and the place is growing. Considerable progress has been made with the helicopter development. I am continuing to work on the manuscript of my next book and recently inserted, in line with your kind permission, the quotation from your letter in connection with the tragic modern situation of the world.” Accompanied by the original mailing envelope. In fine condition. R&R COA.
