Sikorsky S-52Sikorsky S 52 helicopter model. The Sikorsky S 52 was a utility helicopter developed by Sikorsky Aircraft in the late 1940s. It was used by the U. S. Navy, Marines, and Coast Guard. The S 52 was the first US helicopter with all metal rotor blades. A two seater, it was developed into the four seat S 52 2. It was designated HO5S 1 by the U. S. Navy and Marine Corps, HO5S 1G by the Coast Guard, and YH 18A by the Army. Mahogany wood. Scale: 1 24 Length: