For days in late April 1944, Technical Sergeant Ed "Murphy" Hladovcak hid on a jungle ridge in Japanese-held Burma with three sick and wounded British soldiers. His Stinson L-1 had come down beside an enemy-held road, the patrols passed close enough to touch, and the jungle was far too thick for any aeroplane to land.

Then a note fluttered down from a passing aircraft. A helicopter was coming. Almost nobody in the theatre had seen one fly, and the machine on its way was a Sikorsky YR-4B: a fabric-covered, two-seat helicopter whose flight across Burma had already turned into a voyage of its own.

The pilot was Second Lieutenant Carter Harman of the 1st Air Commando Group, a Princeton-educated composer who had volunteered for "heel-e-o-copters" because he weighed less than 150 pounds. What he did next is recognised as the first combat rescue by helicopter.

The machine Sikorsky built for the Army

The Sikorsky R-4 grew directly out of Igor Sikorsky's VS-300, the wobbling test rig that proved a single main rotor and a small tail rotor could work. The Army's prototype, the XR-4, flew in January 1942 and was accepted by the Army that May. According to the National Museum of the United States Air Force, the R-4 became the world's first production helicopter and the first helicopter in USAAF service.

It was not a comfortable aircraft. The three rotor blades were wood ribs over a steel spar, covered in doped fabric, and they were hard to keep turning in the same plane. There was no rotor-speed governor, so the pilot had to match throttle to collective pitch by hand, constantly. The cyclic stick shook so hard that a 1945 newspaper report said a helicopter pilot could be spotted by his permanent case of the shakes.

The numbers were modest even by 1944 standards. The museum lists the production R-4B with a 200 hp Warner R-550 radial, a cruising speed of 65 mph, a range of 130 miles and a service ceiling of 8,000 feet. Sikorsky built 131 of the family between 1942 and 1944, for the USAAF, the US Navy and Coast Guard, and Britain's Royal Air Force and Royal Navy, which called it the Hoverfly.

Its first life-saving work came at home. In January 1944, after the destroyer USS Turner exploded and sank off New York, Coast Guard Commander Frank Erickson flew blood plasma for the casualties in an R-4, an early milestone for United States Coast Guard Aviation.

Combat was a different question, and the people who asked it first were in Burma.

Burma, the air commandos and the eggbeaters

The 1st Air Commando Group was created to support Orde Wingate's Chindits behind Japanese lines. Under Lieutenant Colonels Philip Cochran and John Alison it flew P-51 Mustangs, B-25 Mitchells, C-47s, gliders and swarms of L-1 and L-5 light aircraft. On the night of 5 March 1944 its gliders landed troops at a jungle clearing codenamed Broadway in the opening of Operation Thursday.

Cochran and Alison had also fought to get helicopters onto their roster. Harman and three other pilots shipped out with six dismantled YR-4Bs aboard C-46 transports, a two-week journey via Miami, Puerto Rico, Venezuela, Brazil, Ascension Island and Egypt to Lalaghat in India, where they arrived on 10 March 1944. Only four of the helicopters got there: one was lost with a C-46 that crashed in a storm, and another arrived missing its tail rotor.

The attrition did not stop at the airfield. During test flying at Lalaghat a YR-4B hit a power line, killing pilot Burt Powell and injuring Pete Tierney, and a third pilot, Bob Beaman, was wounded flying a fixed-wing mission. By April, Harman was the only fit helicopter pilot the group had.

He had learned on the type at Sikorsky in Connecticut only months earlier. After two and a half hours of dual instruction he became, by HistoryNet's account, the seventh Army pilot to solo a helicopter, and he finished training after 20 hours on his own.

The US Air Force Life Cycle Management Center's Out of the Hangar series on the first military combat helicopter rescue.

"Send the eggbeater to Taro"

On 21 April 1944 Hladovcak was flying three Chindits out from deep behind the lines, two of them wounded and one sick with malaria, when ground fire hit the fuel line of his L-1. He got it down in a clearing about 150 feet long beside a Japanese-held road and led the men up a ridge into the jungle, where he spread a parachute so friendly pilots could find them.

A ground rescue was impossible and so was a fixed-wing pickup. At Lalaghat, Harman received a terse order: send the eggbeater to Taro. Getting there meant a long detour north with refuelling stops, because the direct route crossed territory the Japanese held and the YR-4B carried only about two hours of fuel.

At Taro, Harman and the mechanics rigged an extra fuel tank, taken from a crashed L-1, in the cockpit above his head. He then crossed Japanese-held country at about 1,200 feet to reach Broadway on 24 April, where he took Cochran up for a ride that ended with an engine failure and an autorotation to the ground. Cochran was impressed anyway, and said so in a letter to a friend.

Heat was the real enemy. Temperatures above 100 degrees Fahrenheit, sometimes 110, cut the YR-4B's lifting power and made its engine stall, and the jungle was too dense for the running take-offs that helped in testing. Harman's answer was a risky jump take-off.

Every pound and every bit of drag mattered. Harman and Sikorsky mechanic Jimmy Phelan had loaded the cockpit with cans of fuel and strapped a stretcher to the outside of the helicopter, where it sat in the rotor downwash. Harman later said it looked like a coffin, and he had to fly against its drag to keep the aircraft straight.

One man at a time

Guided by two L-5s, Harman found a flat spot near the stranded men and landed. Hladovcak limped out of the trees, his knee and elbow battered from carrying one of the soldiers down the ridge on his back, and greeted the pilot with the words HistoryNet records: "You look like an angel."

The YR-4B could take only one passenger, so Harman flew the most seriously hurt soldier to a river sandbar where an L-5 was waiting to carry him on. He went back for a second soldier and ferried him out the same way. Then the overheated engine refused to restart, and with dark falling the rescue paused for the night while Japanese troops searched the jungle around Hladovcak and the last soldier.

A brief rain shower the next morning cooled the engine enough to start. Harman flew in for the third British soldier, then returned one last time for Hladovcak. All four men came out.

Accounts disagree on the exact dates. Wikipedia's R-4 article gives 22 to 23 April, Sikorsky's archive gives 26 to 27 April, and HistoryNet's detailed reconstruction places the pickups on 25 and 26 April 1944. Every account agrees on the essentials: one pilot, one fragile helicopter and four men carried out of enemy territory, one at a time.

The History Guy retells the 1st Air Commando Group's helicopter rescue in Burma.

What the YR-4B started

Harman flew a handful of further casualty evacuations from the Aberdeen base before the monsoon ended helicopter flying in Burma, and he was later awarded the Distinguished Flying Cross. By his own account the surviving YR-4Bs were stored at Asansol in India and, as far as he knew, abandoned there.

Elsewhere the R-4 was proving the same point. In the Philippines in June and July 1945, Second Lieutenant Louis Carle and five other pilots used R-4s to evacuate between 75 and 80 wounded soldiers from the hills northeast of Manila, sometimes under machine-gun fire. Smithsonian historian Roger Connor describes that six-week effort as the largest combat helicopter operation before the Korean War.

Harman himself went back to music. He wrote for The New York Times and Time, composed operas and children's songs, and produced records. His wartime flying was almost forgotten until he and Hladovcak were reunited at the Helicopter Association International meeting in Anaheim in 1986.

An audio programme on the first helicopter combat rescue mission from the Warriors In Their Own Words channel.

The line from his sandbar to today's rescue helicopters is direct. The 1st Air Commando Group's lineage lives on in the Armée de l'air des États-Unis's 1st Special Operations Wing, and every combat rescue crew that drops into a hostile clearing is repeating, with far better machinery, what one underweight composer did in a fabric-bladed Sikorsky in 1944.

Carter Harman died in 2007, aged 88. Hladovcak, who became a flight instructor and a licensed helicopter pilot after the war, had died in 1992. Neither man claimed to have changed warfare, but the four men who walked out of that jungle clearing would have had every reason to say so.

Sources: Wikipedia (Sikorsky R-4, Carter Harman, 1st Special Operations Wing), National Museum of the United States Air Force, HistoryNet, Sikorsky Archives, Vertical Flight Society Vertipedia, Smithsonian Air & Space (via Wikipedia)