Sikorsky R-4 Sikorsky R-4 The Sikorsky R-4 is a two-seat helicopter designed by Igor Sikorsky with a single, three-bladed main rotor and powered by a radial engine. The R-4 was the world's first large-scale mass-produced helicopter and the first helicopter used by the United States Army Air Forces, the United States Navy, the United States Coast Guard and the United Kingdom's Royal Air Force and Royal Navy. In U.S. Navy and U.S. Coast Guard service, the helicopter was known as the Sikorsky HNS-1. In British service, it was known as the Hoverfly. The VS-316 was developed from the famous experimental VS-300 helicopter,
Sikorsky Cypher Sikorsky Cypher The Sikorsky Cypher and Cypher II are types of unmanned aerial vehicles developed by Sikorsky Aircraft. They are vertical takeoff and landing aircraft which use two opposing rotors enclosed in a circular shroud for propulsion. In the late 1980s, Sikorsky Aircraft flew a small UAV named "Cypher", with coaxial rotors inside a torus-shaped airframe. The torus shroud improved handling safety and helped increase lift. The first proof-of-concept Cypher was 1.75 meters (5.75 feet) in diameter and 55 centimeters (1.8 feet) tall, weighed 20 kilograms (43 pounds), and was first flown in the summer of 1988. This design was