Some of the S-56 aircraft ordered by the Marine Corps were converted into radar patrol craft (military designation HR2S-1W), with a bulbous dielectric radome under the nose, but this transformation was unsuccessful.

G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984

The most obvious visual difference between the CH-37 and the Navy HR2S- 1W prototype was the latter's huge chin radome covering the AN/APS-20E search radar. The Navy ultimately abandoned further development of the HR2S-1W because severe airframe vibration severely degraded the radar's performance.

Photo Gallery

This is one of two Navy HR2S-1W helicopters configured for the Airborne Early Warning (AEW) role. The aircraft was not successful in the radar surveillance role mainly because of the vibration inherent in rotary-wing aircraft. A horizontal tail surface was fitted to the right side with the anti-torque tail rotor on the left side.

Technical data for HR2S-1W Engine: 2 x Pratt & WHitney R-2800-50 pistone engine, rated at 1415kW, main rotor diameter: 21.95m, fuselage length: 20.27m, height: 6.71m, take-off weight: 14060kg, max speed: 196km/h, service ceiling: 2438m, range: 354km

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