The Sikorsky H-5 helicopter relied on iron bar weights to maintain its center of gravity.

Countries & Cities · Published 15 October 2026 · Updated 25 October 2026 Swipe more like this →

In short: Before modern flight controls, the pioneering Sikorsky H-5 helicopter faced a strange balancing act. To manage its center of gravity, pilots routinely carried iron bars in the cabin. If they lost these weights, they often had to improvise with rocks or fly at a crawl to stay airborne.

The Sikorsky H-5, initially designated the R-5, was a significant leap forward in rotorcraft technology. Designed to surpass the earlier R-4 model, it featured a more powerful 450-hp Wasp Junior radial engine, a larger rotor diameter, and a longer fuselage. Its first flight occurred on 18 August 1943. By the time production concluded in 1951, more than 300 examples of the various H-5 types had been manufactured, serving roles ranging from utility and rescue to the world's first commercial helicopter operations.

Despite its success, the H-5 suffered from inherent balance issues common to early tandem-seat, single-rotor machines. To compensate, the aircraft was equipped with two iron-bar weights—one of 25 lb and one of 50 lb—housed in canvas cases. Depending on the passenger load, pilots would shift these weights between the forward cabin and the baggage compartment. In high-temperature conditions, where air density reduced lift, these weights were jettisoned to save power. If the crew could not recover them, they were forced to use rocks or other makeshift ballast, or else limit their speed to a mere 25 knots.

The H-5 gained its greatest recognition during the Korean War, where it proved essential for rescuing downed pilots and evacuating wounded personnel from the front lines. Its versatility extended to extreme environments, including the Antarctic, where an HO3S-1 variant became the first helicopter to fly on the continent on Christmas Day 1946. The platform was eventually retired from active U.S. military service in 1957, having paved the way for more advanced successors like the H-19 Chickasaw.

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