Which is the only Bell helicopter with tandem rotors?

Short answer

The Bell HSL (Model 61), an American anti-submarine helicopter of the 1950s built by Bell Helicopter for the US Navy. It was the only tandem-rotor type designed by Bell. The prototype first flew on 3 March 1953, and only 50 examples were built.

Published: November 5, 2026 · Updated: November 5, 2026 · Edited by Above Ten Thousand · Editorial policy

Which is the only Bell helicopter with tandem rotors?

Bell HSL-1 NAN1-54

An anti-submarine helicopter for the Navy

The Bell HSL (Model 61) was an American anti-submarine helicopter of the 1950s built by Bell Helicopter for the United States Navy. It was the only tandem-rotor type designed by Bell. It was powered by a Pratt & Whitney R-2800 radial engine mounted in the rear fuselage. In June 1950 the Model 61 was announced as the winner of the competition, and three XHSL-1 evaluation aircraft were ordered.

Prototype in 1953, service in 1957

The Bell Model 61 prototype first flew on 3 March 1953; it had been designed to meet a US Navy requirement for an anti-submarine warfare helicopter. The type became obsolete during its own development and was considered unsatisfactory when it entered service in 1957. Development problems led to poor adherence to the contract schedule, and only 50 examples were built.

Delivered and stored

All of them were delivered, but after service trials and acceptance only a handful were put to use, for the development of airborne mine sweeping. The rest were delivered straight to storage and eventually struck off charge.