Sikorsky R-4B Hoverfly
U.S. Helicopter

R-4B.jpg (12536 bytes)  

A production R-4B on Okinawa in 1945.

Image source: Robert Kastner from WWII Pacific War Eagles by Jeff Ethell and Warren Bodie. Used with permission.

The first helicopter produced in quantity for the U.S. military forces, the Sikorsky R-4 was developed from the pre-war VS-300 model. The prototype, designated the XR-4 by the USAAF, first flew on 14 January, 1942, powered by a 165 hp Warner R-500 radial engine.

The XR-4 had a single main rotor 36 feet in diameter and a single anti-torque tail rotor. The enclosed cockpit seated two side-by-side with full dual controls. Flying controls were similar to modern helicopters with a cyclic stick, collective pitch lever and rudder pedals for control of the tail rotor.

In 1943, the engine was replaced with a Warner R-550 of 180 hp and the main rotor diameter increased to 38 feet. The same year, the XR-4 made the first landing by a helicopter on a ship at sea, the aircraft carrier USS Bunker Hill.

Given the company designation VS-316A by Sikorsky, thirty were ordered for service trials by the USAAF, three as YR-4As and 27 as YR-4Bs. After tests in both tropical and arctic conditions, three were allocated to the U.S. Coast Guard and seven were sent to the British.

The final production version was the R-4B, 100 of which were ordered in late 1943. Twenty of these went to the U.S. Navy and Coast Guard as HNS-1 for reconnaissance and air/sea rescue missions. Another 45 were supplied to Britain, where they were known as the Hoverfly Mark I.

In 1945, near the end of the war, several R-4Bs saw active service in Burma.

The Ghost Squadron's R-4B is in need of a correct engine and other powertrain components before it can be fully restored to its original condition and placed on static display.


One Pilot and Passenger
Provision for an External Litter

One Warner R-550-1/3 Engine
Air-cooled 7 cylinder Radial
200 hp @ 2,475 for Take-off
180 hp @ 2,100 Rated Power

No Armament

Max. Speed 75 mph @ Sea Level


Climb to 8,000 ft in 45 minutes
Service Ceiling 8,000 ft

Length 48' 1" including rotor
Height 12' 5"
Main Rotor Diameter 38'
Tail Rotor Diameter 7' 8"

Max. Weight 2,540 lbs
Empty Weight 2,011 lbs

Normal Range 130 miles


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