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Although many early helicopter designs held a lot of promise, there were many more that, even with modern technology and materials, likely would never have gotten off the ground.
The de Bothezat quad-rotor-configured helicopter was the first rotorcraft built for the U.S. military; it flew for the first time in October 1922 at McCook Field in Ohio. Jeff Evans Collection Photo
Todays sleek, swift, aerodynamically designed helicopters can be seen almost daily streaking through the skies, but they have a longer heritage than some might imagine: many strange and unusual designs have preceded them over the years. As far back as the mid-1800s, long before the flights of the first practical helicopters took place in the late-1930s, attempts were being made to design, construct and fly a rotary-wing vehicle. (Drawings of helicopter-like devices are known to go as far back as the late-1400s and the Chinese had even created a flying toy as long ago as 400 B.C.E.)
Early helicopters came in all shapes and sizes, with many designs driven more by ingenuity than science. Crafting a helicopter able to fly and hover under control of the pilot was a major challenge for early inventors, as there was no previous knowledge of a flying helicopter to assist the 35 or so known novice pioneers in their initial forays. A number of these inventors, however, did contribute actual science that is still relevant today, but all would suffer from the fact that the rotors and engines needed to achieve lift just werent available in the 1800s.
It was not until the 20th century that this would change, when reciprocating engines had improved enough to allow some helicopter prototypes to finally lift a pilot into the air. In 1907, Paul Cornu of France was said to have been the first to achieve un-tethered (and unsteadied) lift with a pilot, although some now have cast doubt on his claims. Regardless, the helicopters of the time that did achieve manned lift still provided the pilot with virtually no real command of the machine.
Controlling and flying the helicopter was the next problem to be tackled by rotorcraft inventors. Approximately 60 of these visionaries were known to have been working on helicopters up to 1930 or so, spawning many different directions and possibilities some plausible, some downright odd.
So, for your amusement and edification, we present a short history of five particularly unusual helicopters that were designed between the early days of rotary-wing flight in the 1920s, and the more modern era of the 1960s.
The De Bothezat Quad Rotor
In 1921, Russian-born engineer George de Bothezat began work on a rotary-wing aircraft for the United States Army Air Service in a shop he had set up at McCook Field near Dayton, Ohio. The helicopter borrowed from the designs he had originally developed in Russia in 1917, before he came to the U.S. and began working for the National Advisory Committee for Aeronautics (NACA).
De Bothezat and associate Ivan Jerome developed this first rotary-wing aircraft for the U.S. military around four variable-pitch six-bladed main rotors stationed on outriggers, and a powerplant (eventually the Bentley BR-2, 220-horsepower rotary engine) located near the center of the aircraft. The quad-rotor, single-seater also had two vertical propellers to help steer it, along with two small airscrews near the gearbox to act as regulators for the engine. The pilot controlled the helicopter using a stick, foot pedals and a co-axial-type hand wheel operating system.
The 3,700-pound de Bothezat helicopter, which ended up costing $200,000 US, made its first significant flight at McCook Field (now part of Wright-Patterson Air Force Base) on Dec. 18, 1922, rising six feet and staying aloft for one minute and 42 seconds. Two men, Art Smith, an experienced civilian fixed-wing pilot, and Maj. Thurman H. Bane, an Army fixed-wing pilot, were trained to fly the helicopter, which proved to be quite stable in continuous flight.
Although it eventually rose to 15 feet and flew with as many as three passengers, the program came to an end in 1924; the Air Service had lost interest due to the complexity and unreliability of the helicopter, and some say the temperamental nature of de Bothezat. The prototype was stored at McCook Field for some time before being taken apart. The control stick is known to reside in the Smithsonian National Air and Space Museum, and footage of early tests can be found online with some searching.
The Pitts Sky Car
During the same era as de Bothezat, John W. Pitts from Detroit, Mich., designed a helicopter with an uncommon type of rotor system. The main rotor shaft moved up and down, while its 60 rotor blades, arrayed in an umbrella shape, turned and rotated. Vanes under the rotor system moved to assist with the lift of the helicopter.
Pitts first tried his unusual rotor system on an aircraft fuselage, but this was soon rejected in favor of an airframe on wheels, without the aircraft tail capable holding a pilot. The new design weighed 2,700 pounds and was powered by a 90-horsepower Curtiss engine. Unfortunately, the so-called vertical-lift helicopter was far from successful: early tests of the bizarre-looking device in 1928 only resulted in it shaking itself up and down (in a motion one modern writer described as being reminiscent of an irate washing machine). Film clips of the tests can be seen online, generally as part of footage on the early development of helicopters.
The Kellett XR-17 Sky Crane
The Kellett Autogiro Co. (later the Kellett Aircraft Corp.) in Pennsylvania, founded by Wallace Kellett in 1929, manufactured a series of autogyros and helicopters during the 1930s and 1940s. Its most ambitious project, however, began in 1946, when the U.S. Army began looking for a large, experimental helicopter that could carry a 10,000-pound load.
Kellett Aircraft won the Armys contract and began building a pressure-jet, heavy-lift cargo helicopter known as the XR-17 Sky Crane (later designated the XH-17). Created by Kellett chief engineer Richard H. Prewitt, the ambitious design was considered the largest helicopter in the world at the time. Unfortunately, financial problems led Kellett to sell the plans and patents of the XR-17/XH-17 to the Hughes Aircraft Co. of Culver City, Calif., in 1948.
The carry-on Hughes XH-17 helicopter commenced ground testing in late-1949. The operating speed of its massive, two-bladed rotor system which had a diameter of about 130 feet was only 88 r.p.m. Powering it to that rate were two modified General Electric J35 turbojet engines, which supplied air pressure through ducts in the main rotors to burners on the rotor-blade tips.
The helicopters first flight occurred on Oct. 23, 1952, with Gale Moore at the controls. The three-seat ship had a cruising speed of up to 85 miles an hour, but a meager range of only 40 miles. The test program only lasted a few years and was eventually canceled by the military; the gigantic XH-17 was eventually dismantled and scrapped.
The De Lackner DH-4 Heli-Vector
Soon after the XH-17 disappeared, a helicopter from the opposite end of the spectrum appeared: the DH-4 Heli-Vector. Designed by L.C. McCarthy of de Lackner Helicopters, the DH-4 was one of a handful of single-seat, one-person helicopters that arose from the control system work of NACA engineer Charles Zimmerman.
With the DH-4, a lone pilot stood on a small platform above 15-foot-diameter, contra-rotating, two-bladed rotors controlling the helicopter and its 30-horsepower Mercury outboard engine by way of motorcycle handlebars and body movement. There was a pontoon beneath the center of the rotors and four additional pontoons on outriggers to help stabilize the helicopter and keep it from turning over. Its first flight occurred in January 1955; it eventually attained a maximum speed of some 75 m.p.h., with a range of 15 miles (50 miles with an auxiliary fuel tank).
The HZ-1 Aerocycle military model utilized a 55-horsepower Mercury engine with foldable outrigger arms. The U.S. Army evaluated 12 of these aircraft, along with other one-person helicopters, but the program was eventually rejected and abandoned when the craft were judged to be impracticable for military use. A single version of the HZ-1 remains and is exhibited at the U.S. Army Transportation Museum.
The Filper Research Beta 200
The final esoteric helicopter we present is the Filper Research Beta 200, a three-bladed, twin-rotor helicopter fabricated in the mid-1960s. William E. Orrs Filper Research Corp. in San Ramon, Calif., designed this curious-looking, two-seat, consumer-focused helicopter under the direction of engineer J. Ford Johnson. Unique to the design was the gyroflex rigid-rotor system, which saw a vertical rod (complete with balance weights on each end of the rod) positioned near the hub of each rotor blade.
The Beta 200 used the Continental IO-360, 210-horsepower engine mounted in the helicopters nose to power the 20-plus-foot-diameter, rotor system. Cruising speed was 120 m.p.h., and it had a range of up to 400 miles. The first flight of the Beta 200 occurred on May 22, 1966; production models were to be priced at $20,000 US.
Upgraded versions of the Beta 200 included the Beta 300, a six-seater with a retractable undercarriage, a 155-m.p.h. cruising speed and an Allison 250-C18, 317-horsepower turbine engine; and the four-seat Beta 400, with a Continental IO-520, 250-horsepower engine and 150-m.p.h. cruising speed.
Production records indicate 32 Filper Betas were manufactured, but none were ever delivered. The Beta did not receive U.S. Federal Aviation Administration certification; the company went out of business in the late-1960s.
Bob Petite is an air attack officer with the Alberta Forest Protection Division. He has over 40 years of experience working on wildfires both on the ground and in the air, utilizing air tankers and helicopters.
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