Sikorsky R-4

History of the Sikorsky R-4

The Sikorsky R-4 was a two-seater helicopter designed by Igor Sikorsky with a single three-blade main rotor powered by radial engines. The R-4 was the world's first mass-produced helicopter and the first helicopter to be used by the U.S. Army Air Force, U.S. Navy, U.S. Coast Guard and the RAF and Royal Navy.

In service with the U.S. Navy and U.S. Coast Guard, the helicopter was known as the Sikorsky HNS-1. When in service in the UK, it was called the Hoverfly.

After the explosion and sinking of the USS Turner in January 1944, US Coast Guard Commander Frank Erickson flew America's first rescue helicopter aboard a Sikorsky R-4 to deliver life to victims in New York City plasma. On April 22-23, 1944, Lieutenant Carter Harman of the 1st Air Commando of the U.S. Army conducted the first combat rescue using YR-4B helicopters in the China-Burma-India Theater. Harman rescued a crashed liaison pilot and his three British soldier passengers, two at a time, despite the high altitude, humidity and single passenger capacity. Another R-4 rescue on January 22-23, 1945 involved multiple stages of refueling and navigation through a passage between nearly 10,000 ft (3,000 m) mountains to a 4,500 ft (1,400 m) weather station.

Above-average altitude requires a 20-foot (6.1 m) drop to lift off.

While the R-4 was used for rescue purposes in Myanmar and China, it was also used to transport parts between floating aviation maintenance units (part of Operation Ivory Soap) in the South Pacific. On May 23, 1944, six ships went to sea, each carrying two R-4s. The ships were configured as floating repair depots for damaged Army Air Force aircraft in the South Pacific.

When not used to transport parts from one location to another, these helicopters are used for medical evacuation and other rescue missions. Helicopter pilot 2LT Louis Carle is assigned to Brigadier General Clinton W. Russell, 5th Aircraft Maintenance Unit. From June 15 to July 29, 1945, Carr and five other airmen evacuated between 75 and 80 wounded soldiers, one or two at a time, from the highlands northeast of Manila. They were the second group of helicopter pilots after Lieutenant Carter Harman, who used helicopters to evacuate the wounded during World War II. Unlike Haman, they were attacked by Japanese soldiers who tried to shoot them down with machine guns.

Their six-week deployment was the largest deployment of attack helicopters before the Korean War.

On June 15, 1945, the Fifth Air Force received a request from the 38th Infantry Division to evacuate two soldiers with head wounds 35 miles (56 km) east of Manila. Carl took a Sikorsky R-4 helicopter from his ship and landed near the front line to the surprise of soldiers who had never seen a helicopter. The helicopter was not equipped with a stretcher, and they removed a seat and placed the wounded on the plane's floor. Carl transports soldiers to the 311th General Field Hospital near Manila.

It turned out that they had been on the phone while they were away. Carl flew seven hours and conducted six evacuations on the same day.

When in service with the Royal Air Force, the R-4 was known as the Hoverfly. The Helicopter Training School was established in RAF Andover in January 1945 and was the first British military unit to be equipped with a helicopter.

Many RAF Hoverfly Mark Is were sent to the Royal Navy for training and one was used by Fairey Aviation in 1945-46 to develop rotor systems for its Gyrodyne helicopters.

Specification

Base

Year of Service

1942

Origins

United States

Crew

1

Production

131

Manufacturer

Sikorsky - USA

Carrier

Canada; UK; US

Roles

Transportation

General transport function for moving supplies/cargo or people (including casualties and VIPs) out of range.

Dimensions and Weight

Length

33.5 feet

(10.20m)

Width/span

37.7 feet

(11.50m)

Height

12.5 feet

(3.80m)

Cured weight

2,094 lbs

(950kg)

MTOW

2,646 lbs

(1,200 kg)

Wgt Difference

+551 lbs

(+250kg)

Performance

Installed:

1 x Warner R-550 piston engine, 200 hp.

Maximum speed

75 km/h

(120 km/h | 65 kn)

Maximum

7,874 feet

(2,400 m | 1 km)

Range (MPH) Subsonic: <614mph | Transonic: 614-921 | Supersonic: 921-3836 | Hypersonic: 3836-7673 | Hypersonic: 7673-19180 | Reentry: > 19030

Armor

None.

VARIANTS

XR-4 - Single prototype model; equipped with 165 hp R-500-3 series engine. YR-4A - Development model with 180 hp R-550-1 engine; larger diameter rotors for improved lift; 3 examples complete. YR-4B - US Army Formal Evaluation Development Model; 27 copies produced. R-4B - R-4 series production code; R-550-3 series engine with 200 hp; 100 copies made. XR-4C - Prototype model with 180 hp R-550-1 engine; modified rotor.

HNS-1 - The US Navy designates three YR-4B and twenty-two R-4B variants. "Hoverfly I" - British military designation for the R-4 production model; 52 examples provided. S-54 - R-4B testbed with added observer position.