4 August 1950: During the Battle of the Pusan Perimeter, wounded soldiers were evacuated from the battlefield by helicopter for the first time when a Sikorsky H-5F of Detachment F, 3rd Emergency Rescue Squadron,¹ Air Rescue Service, United States Air Force, flew Private 1st Class Claude C. Crest, Jr., U.S. Army, from the Sengdang-ni area to an Army hospital. By the end of combat in 1953, 21,212 soldiers had been medevaced by helicopters.
Only the second military helicopter, the H-5 was frequently flown overloaded and outside of its center of gravity limits. The helicopter was not armed, though the pilot normally carried an M1911 .45-caliber semi-automatic pistol, and the crewman, a .30-caliber M1 Carbine.
The helicopter’s fuselage was 41 feet, 1¾ inches (12.541 meters) long. The main rotor had a diameter of 48 feet, 0 inches (14.630 meters) and the tail rotor diameter was 8 feet, 5 inches (2.565 meters),² giving the helicopter an overall length of 57 feet, ½ inch (17.386 meters) with rotors turning. It was 12 feet, 11–3/8 inches (3.947 meters) high. The tricycle landing gear had a wheel base of 10 feet, 1 inch (3.073 and the tread was 12 feet, 0 inches (3.658 meters). The S-51 had an empty weight of 4,050 pounds (1,837 kilograms) and maximum gross weight of 5,300 pounds (2,404 kilograms) below 1,000 feet (305 meters) MSL.³ Fuel capacity was 100 gallons (379 liters).
The H-5F had a maximum speed (VNE) of 107 knots (123 miles per hour/198 kilometers per hour). Range was 275 miles (443 kilometers). The service ceiling was 14,800 feet (4,511 meters). The absolute hover ceiling was 3,000 feet (914 meters).
¹ Reorganized as the 3rd Air Rescue Squadron 10 August 1950.
² An 8 foot, 9 inch (2.667 meter) all-metal two-blade tail rotor assembly became standard with the H-5G, and was available to retrofit earlier helicopters.
³ The maximum gross weight had to be reduced 150 pounds (68 kilograms) for each additional 1,000 feet of altitude.
© 2018, Bryan R. Swopes
On May 16th, 1950 Col. Santini of the French Air Force carried out a medevac with a Hiller 360 at Tan-Uyen in Southern Vietnam (Cochinchina in those days). Unless the British carried out any similar missions earlier in Malaya, this qualifies as the first military helicopter medevac in history. The rescue of stranded passengers from SABENA’s crashed DC4 OO-CBG in Gander in December 1946 is the very first chopper medevac.
The 1st Air Commando Group, the first helicopter combat mission, the first helicopter combat rescue.
April 1944 – Lt. Mark Harmon, US Army. WWII, Burma in Sikorsky YR-4B.
Kyron, please see This Day in Aviation for 21–25 April 1944: https://www.thisdayinaviation.com/21-april-1944/
Bryan, All the reference sources I have seen for the Wasp Jr. list it as having a 2-piece aluminum alloy crankcase and not magnesium. My source is Aircraft Engines of the World 1946 by Paul H. Wilkinson. I look foward to reading TDiA every day and enjoy very much.
Thanks, Carl, but I think I’m right on this one: My source is a data sheet from Pratt & Whitney Aircraft Engines, dated July 2, 1956. Notes on the specific model engine state that the R-985 AN-5 is for “Vertical installation. Magnesium crankcase.”
Hello Bryan. Like so many other commenters, I must tell you how much I enjoy reading your blog every day! It’s great and I appreciate your efforts.
Question for you…It seems the usual descriptions of helicopters includes the info that the advancing rotor blade is on the right side of the chopper. Is that significant? Is there an advantage to counterclockwise rotor rotation? I’m a fixed wing guy and don’t know much about rotorcraft. I’d love to read your educated info about this. Thanks!
Thank you,very much, James. Excellent question!!!! Yes, helicopters built by France and the Soviet Union have rotor systems that rotate in the opposite direction from American, British, Italian or Japanese models. It had to do with the configuration of the engines installed in the early models. (For example, the earliest Sikorsky prototypes used a radial engine mounted with the crankshaft vertical and nose facing upward.) I have flown both types and am not aware of any advantage to one over the other. Because the torque reaction to the turning main rotor is in the opposite direction, the pilot must use the tail rotor control pedals to compensate for increases and decreases in engine power and to control yaw. In a Bell JetRanger, for example, when the pilot increases engine power and collective pitch to lift off to a hover, the helicopter yaws to the RIGHT and he must push the left pedal forward, increasing the thrust produced by the tail rotor, to keep the nose pointed straight ahead. When he puts the helicopter into a descent and reduces power and collective pitch, he has to push forward on the right pedal. During flight, everything is in a constant state of change, and a pilot learns with experience to make changes in the tail rotor control pedals instinctively. Now, switch to an Aérospatiale Écureuil (known as an A-Star here in the U.S.). With the main rotor turning in the opposite direction, the torque reaction is also opposite. When the pilot increases power to lift off, the helicopter yaws to the LEFT and he must push the right pedal forward to keep the nose of the helicopter straight ahead. A pilot who has learned to fly on one system can become quite frustrated when changing to the other, because his learned “instinctive” responses are all wrong. He pushes on the wrong pedal and the yaw increases. Not having the desired effect, he pushes on the wrong pedal harder, and the helicopter goes merrily spinning off on its own. But he learns. Eventually. [In tandem rotor helicopters, the main rotors turn in opposite directions and their associated torque reactions cancel each other out.] And then there is Translating Tendency. . . The tail rotor counteracts the torque reaction of the main rotor with thrust. When the helicopter is at a stationary hover, this thrust moves the helicopter sideways. The main rotor mast of the JetRanger, as an example, actually is not vertical, but “leans” about 4° forward (to keep the cabin fairly level at cruise speed) and a little over 1° to the left to provide some built in compensation for translating tendency. (I can’t find my Pilot Transition Notebook which has the exact figures—I think that I left it in my office at my last job.) So, if the torque reaction is opposite, the tail rotor thrust must be opposite to compensate, and the translating tendency is opposite. The pilot must then move the cyclic stick in the opposite direction ever so slightly to cancel this lateral motion. . . Thank you for the question, James. It got my mind back in the cockpit for a while.
Very interesting. Thank you for your detailed and informative reply Bryan!