First seeing combat in Vietnam, the UH-1 Iroquois helicopter, nicknamed the Huey, became one of the most successful rotary-winged aircraft in aviation history, with more than 16,000 produced. Throughout the Vietnam War, all five branches of the United States Armed Forces and hundreds of civilian agencies used it for almost every mission, including troop transport, gunship operations, airborne battlefield command and control, troop insertion and extraction, medical evacuation, and search and rescue. It was enormously successful in Vietnam because of its ideal mix of cabin room, speed, lifting capacity, ruggedness, and service reliability. The UH-1 had an 850-shaft-horsepower gas turbine engine and was configured for up to fifteen seats or six stretchers and a medic. Vietnam veterans identify with the Huey's distinctive whop, whop, whop sound that often signaled life-saving help.