Piasecki H-21 Workhorse

History

The Piasecki H-21 tandem rotor helicopter evolved from a series of Piasecki products starting with the HRP-1. The HRP-1 used a tandem rotor arrangement and first flew in 1945, eventually being adopted by the U.S. Navy, Marine Corps, and Coast Guard. In service since 1947, 28 examples were completed. This frame appeared in the H-21 in the late 1940s, which was modeled after the Cold Weather Rescue Service.

The U.S. Air Force ordered 32 prototypes of this type, calling them the H-21 "workhorse." Due to its distinctive shape, the H-21 - and its predecessor - earned the nickname "Flying Banana". The first flight took place in April 1952, and its design is credited to Frank Piasechi himself.

The H-21 is based on the HRP-1, but incorporates more modern elements into its design for a stronger end product. The cockpit is designed with heavy glass to improve crew visibility and is located at the very forward end of the fuselage. The fuselage was pulled aft midship, giving the cockpit a "nose-up" look, while also raising the stern - giving the H-21 its most distinctive look. At the lowest point of the fuselage are the fixed (wheeled) main landing gear legs, which remain under the nose. Each main rotor consists of three blade assemblies, and the folded center of the fuselage ensures that the main rotor blades do not interact at any time - reducing the likelihood of a fatal accident.

Their rotation is counter-rotating to reduce inherent torque and maximize control/stability. The vertical tail is located beyond the position of the rear main rotor. Internally, the H-21 has a two-person crew in the cockpit and can accommodate up to 20 fully loaded combat troops or up to 12 medical limousines and accompanying medical personnel.

Performance includes a top speed of over 130 mph and a range of up to 400 miles.

The H-21A marks an early USAF Search and Rescue (SAR) model with a 1,150 hp Curtiss-Wright R-1820-103 "Cyclone" supercharged air-cooled radial engine. The brand counted a total of 32 aircraft, followed by the "H-21B", which developed into an attack transport aircraft through 163. The engine was changed to a Wright 103 model rated at 1,425 hp for better performance. Additionally, the diameter of the main rotor blades increases as the blades are lengthened by approximately 6 inches.

The United States Air Force was soon joined by the Royal Canadian Air Force (RCAF), operating the H-21 series (A and B).

In the early 1950s, the U.S. Marine Corps was interested in the H-21, and several H-21A models were used for evaluation. In 1957, an H-21B arrived and was used as a tugboat. The H-21C is the designation for the U.S. Army under the designation "Shawnee" and is powered by the Wright 103 engine.

These were later renamed the "CH-21" model designation.

The H-21s were produced from 1952 to 1959, and they remained in service until 1967. In addition to the US and Canada, global operators include France, West Germany, Japan and Sweden. New York Airlines is in civilian form because several models of the line are designed to carry passengers.

During the Algerian War (1954-1962), the French forced their H-21C models into combat service, playing the role of gunboats, armed with rockets and machine guns, although this exposure was far from a complete success. Despite this, the helicopter continued to perform its assigned transport mission until the end of the French operation.

The U.S. H-21 fought during the Vietnam War (1955-1975) in December 1961, usually armed with trainable 7.62mm and 12.7mm machine guns for defensive purposes. However, their service in the conflict was relatively short, as the new Bell UH-1 Huey and Boeing CH-47 Chinook series helicopters were successfully deployed on the battlefield. The former excels at attack/gunships, while the latter continues the tradition of tandem rotors and is cleared for heavy transport. The war revealed several shortcomings of the H-21 designslow performance, vulnerability to ground fire, and poor handling in hot weather.

From 1964, their military service was greatly reduced.

On August 24, 1954, a U.S. Army H-21C became the first helicopter to fly non-stop to the United States. Aerial refueling made this feat possible.

In 1959, Vertol Aircraft acquired the company Piasecki, which later became Boeing Vertol. A heavy-duty H-21 version was considered, including an attached H-21 fuselage that could carry very heavy loads (the number of H-21s involved may vary depending on the weight of the cargo).

The idea has not been put into use in form.

Specification

Basic

Production

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Dimensions

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Performance

Performance

Armor

Changes