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2011-01-19
History of the Autogyro - Eric Torr


History of the Autogyro

      Now that it is known how autogyros work, some of their characteristics of flight, and how those characteristics differ from airplanes and helicopters, it would be nice to know how all this developed. The early history of the autogyro is basically a history of one man, don Juan de la Cierva.

Juan de la Cierva
Photo courtesy Dr. Bruce Charnov

Cierva was born in Murcia, Spain, September 21, 1895. He was only eight years old when the Wright brothers first flew on Dec. 17, 1903. He was a young man on his way to becoming a civil engineer when they first demonstrated their machine to the rest of the world in France in 1908. Cierva was intrigued by this new technology and decided to build his own airplane. His first attempt was to rebuild a Sommer biplane. He fitted it with a new engine and made several modifications to the original airplane. When he completed the project in 1912, he named the airplane the BCD-1 El Cangrejo, Spanish for the BCD-1 Crab.

 

BCD-1 Cangrejo
Photo courtesy Dr. Bruce Charnov

The plane flew well and was considered to be the first Spanish built airplane. Cierva's second attempt was the BCD-2, a small monoplane, which he built in 1913. It did not fly as well as the BCD-1 and crashed. It was rebuilt, but crashed again. The design was abandoned. Cierva's third and final airplane design was the C-3. It was for a Spanish military competition announced in September of 1918. The C-3 was entered into the bomber division of the contest. The plane was a large tri-motor biplane, and was completed in May of 1919. It flew well, but in one of the preliminary tests the pilot flew the plane too slow and it stalled. The plane was wrecked, but the pilot escaped without serious injury. This crash disappointed Cierva, and inspired him to think of a better way to fly at low speeds. After tossing a toy helicopter from his parents balcony and studying the flight, Cierva came up with the idea of an autogyro, which he called the autogiro (Notice the spelling with an "i" instead of a "y").

      Cierva's first attempt at building an autogyro was the C.1. The C.1 had two counter-rotating rotors to provide lift and by counter-rotating to eliminate torque. A vertical control surface above the rotors was meant to provide lateral control, while a conventional tail rudder and elevators would provide control about the other axes. Unfortunately, this design never flew. Because of the interactions between the two rotors, the top spun faster than the bottom. This upset the balance in lift and torque, causing the machine to tilt to one side. However, when it was tested, in October of 1920, it did demonstrate successfully the principles of autorotation while taxiing on the ground.

      After the C.1, Cierva started work on his next design, the C.2. The C.2, was to have only one rotor, consisting of five blades, with duralumin spars. Because of difficulty in obtaining the duralumin, and because of a shortage of funds, work on the C.2 was postponed and Cierva began work on the C.3.

 

Cierva C.3 Autogyro
Photo courtesy Dr. Bruce Charnov

      The C.3 was completed in June of 1921. The C.3 had one rotor with three blades. He still had a rudder and elevator for yaw and pitch control, but for lateral control he tried collective pitch variation. This refers to changing the angle of all the different blades at the same time. However this design proved to be impractical, and the C.3 only achieved brief hops of a few inches off the ground.

      Once done with the C.3, Cierva went back to the C.2. The C.2 was finally completed early in 1922. It had similar controls to the C.3. It achieved slightly better lateral control, and short hops of a few feet above the ground, but still couldn't maintain sustained flight.

      One of the problems with Cierva's three designs up to this point was that the rotor was rigid. This created two problems. First was that it created a gyroscopic effect. As soon as the aircraft tried to move, this effect would cause the aircraft to tilt. The other problem came from unbalanced lift. As the rotor was spinning, one side would be moving the same way the aircraft was moving, increasing the relative wind speed, while the other side would be moving opposite the direction the aircraft was moving, decreasing the relative wind speed. The side with the higher relative wind speed would have a higher lift than the side with lower relative wind speed, causing the aircraft to tilt. Cierva came up with a solution to this problem while watching an opera. One of the props for the opera was a windmill with hinged blades. Cierva decided to use hinges in his rotor designs. This allowed the blades to rise and fall depending on what direction they were moving in. The blades moving with the aircraft rose because of the higher lift, but this also served to decrease their angle of attack. The blades traveling in the opposite direction of they autogyro would fall because of the lower lift, serving to increase their angle of attack. The combination of the rising and falling action, which came to be known as flapping, and the increase and decease this had on the angle of attack served to balance the lifts created on each side of the aircraft. The hinged blades also eliminated the gyroscopic effect caused by the rigid blades.

      Cierva's next design, the C.4, incorporated these hinged rotors. For lateral control, ailerons were mounted on outriggers to the side of the aircraft. Yaw and pitch control still came from a rudder and elevators. On January 17, 1923, the C.4 flew, marking the first controlled flight of an autogyro. The C.4 also demonstrated the autogyro's safety in low speed flight. On January 20, three days after its first flight, the autogiro went into a steep nose-up attitude after an engine failure at about 25-35 ft. In an airplane, this would have almost certainly resulted in an almost unrecoverable stall. But the autogyro just descended gently to the ground without damage to the machine or injury to the pilot. This low speed safety was demonstrated even more dramatically on January 16, 1925, when another design, the C.6, lost power after take-off at about 150-200 ft. The pilot was still able to turn the autogyro around and bring it in for a safe landing, with only slight damage to the machine. This maneuver would have been much more difficult in an airplane, and quite possibly could have led to a worse accident.

 

Cierva C.4 Autogyro
Photos courtesy Dr. Bruce Charnov

      Another problem with early autogyros was rotor spin-up. To achieve autorotation, the rotor had to be spun to a minimum speed before the aircraft began moving. In early autogyros, this was achieved mainly in four ways, spinning the rotor by hand if the rotor was small enough, or if it was bigger, with a team of horses, a team of people, or by connecting it to a car engine through a drive shaft. This need for an external source to spin the rotor kept the autogyro from being a self sufficient machine capable of working anywhere. Cierva's solution for this problem was to design the tail in such a way that it would deflect the slipstream from the propeller up into the rotor. This deflected wind would cause the rotor to spin up. It was achieved simply by adding flaps to the tail that angled upwards. This design was known as a scorpion tail. He tested this idea on a C.19 in 1929. The problem was that the tail did not deflect enough wind. The rotor did spun some, but not to the minimum speed needed for takeoff. A short takeoff run was still needed to spin the rotor the rest of the way. Another method used to solve the problem of rotor spin-up was, instead of connecting a drive shaft to a car, just connect it right to the autogyro's engine. The first attempt to do this was in a modified C.11 early in 1930. A drive shaft was connected to the engine through a clutch. Unfortunately, this mechanism weighed about 165 lb. and was too heavy for the autogyro to fly. An improved clutch and drive shaft system was introduced late in 1930. It was first used in April 1931 on the PCA-2, an autogyro developed by Harold Pitcairn, who had the licensing rights for Cierva's invention in the United States. The drive shaft and clutch system wasn't used on a Cierva design until almost a year later in March of 1932 on the C.19. This new design worked well on both the PCA-2 and the C.19, and became the dominant style of spin-up in all later models of autogyros where the rotor was too large to be spun by hand.

      The next major advance in autogyros came on August 5, 1931. This was the first flight of the Wilford WRK. This new autogyro replaced the hinged rotors with a rigid rotor with cyclic pitch variation. Cyclic pitch variation is a method where the pitch of the blades is changed as they spin. The pitch is lowered when they are moving in the direction of the aircraft, and raised when they are moving in the opposite direction. This does the same thing as flapping to balance the lift created by the blades. The WRK was the first autogyro to successfully fly with a rigid rotor.

      Earlier in this paper, it was stated that autogyros have the potential for vertical take off and landing. Although all the autogyros discussed so far have been capable of vertical landings at least in an emergency, they have also all needed some minimum takeoff run. But, if the rotor was powered before take off to make it spin at the minimum speed for autorotation, why not just continue to power it to a higher speed and take off from the lift created that way. That is exactly what happened. In August of 1933, experiments were begun on a C.30 in this new method of takeoff, which came to be known as a jump takeoff. These first experiments were promising, but not satisfactory. Spinning the rotor on the ground caused too much vibration, and the aircraft was only capable of making low jumps. By October 28, 1934, after over a year of experimenting and refining, the C.30 finally made a successful jump takeoff. Many later autogyros were also designed for jump takeoffs, most using the same method as the C.30. A few later autogyros had tip driven motors where either a jet or a rocket was put at the end of each rotor blade to spin the rotor that way.

 

Cierva C.30 Autogyro
Photo courtesy Dr. Bruce Charnov

      The C.30, besides being the first autogyro to make a successful jump takeoff, was notable for another aspect as well. It was the first autogyro to use direct control. Direct control was a method where the pilot tilted the rotor instead of a rudder and ailerons. This greatly simplified the control of the aircraft, as well as the design. A pilot now had one control for yaw, pitch, and roll, and designers only needed to design that one control. In the C.30 and later autogyros of comparable size, this consisted of a bar connected directly to the rotor hub that extended into the cockpit. For larger machines, the controls of the pilot were mechanically linked to the rotor hub. The C.30 also proved to be the most popular production autogyro ever designed, with more than 180 of them being built.

      On June 26, 1935, the Breguet-Dorand 314 was the first successful helicopter to fly. It incorporated many of the features developed for autogyros, such as collective and cyclic pitch control. On December 8, 1941, Igor Sikorsky's V.S.300 flew, another of the first successful helicopters. The V.S.300 was only a test aircraft, but led to the VS-316, a more refined helicopter using the same principles. The U.S. Army ordered the VS-316, and 400 of these aircraft were produced along with the R-5 and R-6, two other Sikorsky helicopters of similar design.

Why Autogyros Weren't Accepted

      At this point we can ask the question of why autogyros were never widely accepted. Just about every aviation historian has their own answers to this question, but here is this author's opinion. Early autogyros, although they had a higher speed envelope than airplanes, had a higher drag and so were not as efficient at higher speeds, and absolutely could not attain the maximum speeds of the faster airplanes. Also, the early autogyros did not have the vertical takeoff and landing capabilities that would have made them more attractive to potential buyers. When the C.30 finally demonstrated a successful jump takeoff in 1934, it was less than a year until the first successful helicopter flew, and only a few more years until the very successful Sikorsky V.S.300 and VS-316. Although helicopters had a smaller speed envelope than autogyros, they were capable of hovering, and their envelope could fill the role that airplanes couldn't. In other words, anything an autogyro could do could be done by another aircraft. Also, Cierva, who was doing most of the development of autogyros, was funding much of the development on his own. When the army ordered the VS-316, that money went in to Sikorsky's company. This gave Sikorsky the funding for development that Cierva was running out of. Without the money, Cierva just couldn't fund the research. And then, on December 9, 1936, Cierva was killed in a plane crash (a DC-2 operated by KLM). He was only 41 years old. There were other people developing autogyros, but Cierva had been one of the main driving forces behind the movement. Much was lost when he was killed.

      Another factor that kept the autogyro from being accepted was purely psychological. Even though helicopters weren't successful until 1935, they had been under development for as long as airplanes. The general public knew about helicopters, and understood the principle of a powered rotor. Autogyros had an unpowered rotor that spun due to aerodynamic forces. Most people did not understand how it worked and so did not trust it. Although it is actually safer than either helicopters or airplanes, people did not realize this. They wanted something powered.

Autogyros After Helicopters

      After helicopters flew successfully and the companies that designed them got military grants for further research, the autogyro was pretty much abandoned. Except for a few concepts and only a handful of attempts at civil designs, autogyros were kept alive only as home built aircraft, and that mostly as ultralights. Recently, there have been two companies to resurrect the idea of the autogyro, Groen Brothers and CarterCopter.

      The Groen Brothers design is the more conventional of the two. The unique innovation of the Groen Brothers machine is that it is using ram jets at the tips of its rotor blades to power them for spin up. Ram jets are not very efficient engines, but they will only need to be run for ten to fifteen seconds, so efficiency is not much of an issue. The ram jets will spin the rotor fast enough to enable the machine to take off vertically. Their autogyro will also use a collective pitch control to help reduce drag. It is being marketed to corporations that currently use helicopters, or can't quite afford helicopters, to travel from rooftops in cities. These corporations really have no need for hover, they just need to be able to take off and land vertically. The autogyro can do this faster and for less money than a helicopter. They are also trying to market it to organizations that only need low speed flight and not complete hover. In fact, most observation of stationary objects done by a helicopter is done by flying above it in slow circles, not just hovering.

      The CarterCopter is more of a hybrid between an airplane and an autogyro. The rotor will be spun up with a conventional drive shaft and clutch system, but the rotors will have 60 pound weights at their tips. This will cause the rotor to function as a flywheel for the jump takeoff. It also allows the rotor to be slowed down in cruise and still maintain enough rigidity from centrifugal force to be stable. Once flying, the pitch on the rotor blades will be lowered as much as possible to reduce the drag created by them to as little as possible. The lift will come from conventional airplane wings mounted on the sides of the aircraft. The company is predicting that the CarterCopter could surpass the performance of all aircraft except jet propelled airplanes and spacecraft. This includes helicopters, all previous autogyros, piston powered prop planes, and turboprop airplanes. With a turboprop engine, the craft should be able to fly 400 mph at 45,000 feet. A modified propeller version could be able to fly at 70,000 ft., while a jet powered version could fly 500 mph or more. A specially modified version of the aircraft should be able to fly 25,500 miles on one tank of gas, which would allow it to equal the Voyager's round the world flight of 1986, but with a vertical takeoff and landing. With its performance, the CarterCopter would not only be able to fill the roles the Groen Brothers would like to fill, but also those currently belonging to propeller driven aircraft. (In the interest of full disclosure, it should be stated that the author is an employee of Carter Aviation Technologies - although the CarterCopter was included in the original version of this paper while the author was still a student.)

Concluding Remarks

      Autogyros were the first successful rotary wing aircraft to fly. They marked a departure from conventional fixed wing aircraft and an attempt to fill a role that airplanes couldn't. They can fly slowly due to a phenomenon known as autorotation, where the rotor is unpowered and is made to spin by aerodynamic forces. Autorotation allowed the wings to move faster than the aircraft. Although autogyros were never widely accepted by the public, the military, nor aircraft companies, they were very important in the development of the helicopter. Many technologies essential for practical helicopters were first developed for the autogyro. If Cierva had not pursued the autogyro, it almost certainly would have delayed the development of the helicopter, maybe even for decades. After the introduction of the first successful helicopters, autogyros were largely forgotten except as kit aircraft and ultralights. Recently, two companies, Groen Brothers and CarterCopter, have brought back the autogyro using modern technologies. Neither plans to replace the helicopter entirely, only in places where low speed flight or vertical take off and landing are all that are needed. Perhaps, if these companies have their way, the future will be more kind to the autogyro than has the past.

References

About Gyroplanes. Internet Resource: http://www.saskia.com/~zlinak/about-copters.htm (No Longer Available)

Brie, Reginald. The Autogiro and How to Fly It. Bath: Pitman Press, 1934

Brooks, Peter W. Cierva Autogiros. Washington: Smithsonian Institution Press, 1988

CarterCopters, Inc. Internet Resource: http://www.cartercopters.com/

Garvey, William. "Gyrocopters Grow Up." Popular Mechanics, June 1996

The Groen Brothers Aviation Home Page. Internet Resource: http://www.groenbros.com/

Rotorcraft Page. Internet Resource: http://www.rotorcraft.com

The gyrocopter was invented by the Spanish engineer Juan de la Cierva. In 1921, he participated in a design competition to develop a bomber for the Spanish military. De la Cierva designed a three-engined aircraft, but during an early test flight, the bomber stalled and crashed. De la Cierva was troubled by the stall phenomenon and vowed to develop an aircraft that could fly safely at low airspeeds. The result was the first successful rotorcraft, which he named Autogiro in 1923.

In World War II, Germany pioneered a very small gyro glider rotor kite, the Focke-Achgelis Fa 330 "Bachstelze" (Water-wagtail), towed by U-boats to provide aerial surveillance.

The autogyro was used to calibrate the coastal radar stations during and after the Battle of Britain.

The Japanese Army developed the Kayaba Ka-1 Autogyro for reconnaissance, artillery-spotting, and anti-submarine uses. The craft was initially developed for use as an observation platform and for artillery spotting duties.

 

Gyroplane Notations (A Historical Look at the Progress of the Autogyro/Gyroplane)

1920. Juan de la Cierva, A Spanish noble with a great entreuprenarial passion to develop a stable aircraft that would not stall, begins development of the autogiro. Cierva used existing airframes and modified them with his windmilling rotor.

Cierva's first model aircraft were wingless and not very successful due to problems of controlling the rotor dynamically. Cierva continued to learn and develop the rotor. The first signs he was on the right track occurred near the end of 1922 with rotor blades made of bamboo that were allowed to free flap. Rotor blades allowed to free flap lets them raise and lower themselves dependant on the relative wind. In this manner Juan de la Cierva solved the problem of gyroscopic torque, roll stability. By developing this technology Cierva found a means to prevent the aircraft from rolling over. This technology is still used today on modern gyroplanes and was the direct link to a successful helicopter.

Cierva's model C-4 was the first airworthy autogiro and flew from Madrid on January 9, 1923. This aircraft averaged a 37 mph speed on a 110 hp radial engine. The model C-5 quickly followed the C-4. The C-5 was outfitted with a three bladed rotor versus the four bladed rotor found on the C-4. The C-5 in turn gave way to the C-6 in 1924.

In 1928 Cierva develops the C-8 and in September becomes the first rotorcraft to cross the English Channel. With all these successes, Cierva moves to England and finds the Cierva Autogiro Company. Cierva granted licenses to several airplane manufacturers in the late 20's and early 30's. Manufacturers like DeHavilland, Avro, Panall, and Westland. The development intrest faded when Cierva was killed in an airline crash in 1936.

Development did progress forward with a company called G&J Weir in Scottland. An engineering firm that started building autogiros under liscense of Cierva in 1932. Their first works evolved around the single seat C-28 but powered with a Douglas Dryad engine of 40 hp and renamed the ship Weir W.1.

The W.1 was further developed into the W.2 with "jump start" capability. Further refinement saw the introductions of the W.3 and W.4 with jump takeoff capability on a 50 hp Weir engine and two bladed rotor system.

In 1937 Weir decided to concentrate on helicopter development and succeded with the W.5. The W.5 was the first successful British helicopter and flew in June 1938.

A small company in Willowgrove PA, USA started work in 1929 as the Pitcairn Autogiro Company. Founded by Harold Pitcairn. Pitcairn had met with Cierva in the UK and made patent and license agreements to develop autogiros in the United States. This Company made several types of autogyros and later the company was changed to the G&A Aircraft Division of Firestone.

Pitcairn developed the PCA-1 based off an airplane the company made called the Pitcairn Mailwing and used the rotor system from the C-19. From the development of the PCA-1 a far more improved two seat aircraft was built designated the PCA-2. The PCA-2 was powered by a Wright 300 hp radial engine and the first certificated gyroplane in the United States. This aircraft also set an altiitude record of 18,415 feet. Twenty of these aircraft were built with several delivered to the U.S. Navy as XOP-1 for ship trials.

A smaller version of the PCA-2 was manufactureed as the PAA-1 and was powered by a 125 hp engine and four bladed rotor. The rotor had a unique control that allowed the rotor to be tilted fore and aft for increased stability. About twenty of these aircraft were also made.

The PA-18 was developed after the PAA-1, between 1932 and 1933. It is interesting to note the autogiro was priced at $6,750.00 and included pilot training.

The Pitcairn Company gave the United States it's largest gyroplane in 1932 with a cabin version in four-place arrangement, called the PA-19. The 19 was powered by a 420 Wright engine with a four bladed rotor with trim control. Trim was possible by the pilot tilting the head perpendicular to the fuselage axis. This rotor design predated a similar development the Cierva Company was to later develop in England.

The Pitcairn Company manufactured many more models over the years with final design of the PA-39. In 1941 the British Air Commission requested seven of these aircraft for evaluation for its Navy in an anti-submarine role. Unfortunately some aircraft were lost in the shipment to the United Kingdom and intrest in the project changed, resulting in the endeavor being cancelled.

In 1934 Westland built an experimental autogyro designated the C-29 with a four-place cabin. The project was cancelled due to excessive problems with resonance.

Kellet manufactured Cierva liscenced autogiros in the United States in 1934 with the two-place, folding three bladed rotor, KD-1. A small single place type was later developed and used by Eastern Airlines to carry mail. A further development of this aircraft for the United States Army was made and called the YO-06 with a 300 hp Jacobs R-915 engine. The design was to be utilized in an observation role and was built in 1942.

Kellets Autogiro's were copied in Japan with German Kobe in-line engines of 240 hp and designated Kayaba KA-1.

At this point in gyroplane history much attention was shifted from the development of gyroplanes to helicopter research and development. A notable autogyro from this period was the Rotochute that would later inspire the Bensen series of light gyrocopters.

1942, Germany. The German Navy used the Focke Achgelis Fa 330 with its submarines for reconnaissance work. The 330 had no engine as it was towed by cable from the submarine. The craft was a single seat design with three bladed rotor system. Weser Flugzeugwerk produced around 200 of the type before the close of World War II.

This note is a bit off topic but I think you will find interesting:

A great helicopter designer was German, Anton Flettner. Flettner's first model flew in 1932 and he continued to improve and make changes to his designs. When in 1939 he developed an aircraft that the German Navy took intrest. Flettner delivered 30 prototypes of the new two-place Fl 282 Kolibri that the Navy planned to use for anti-submarine reconnasissance. The first of these ships flew in 1941. The original enclosed cabin was a multi-faceted design but with time constraints many were built with an open cockpit and retained the lower plexi-glass cabin. By 1942 the 282 was in active service on operational warships. The Kolibri became the world's first military helicopter. The intermeshing rotors would later find their use in designs by Kellet and Kaman.

1947, United Kingdom. The Fairey Aviation Company develops a four seat experimental aircraft called the Fairey Gyrodyne. The gyrodyne was technically a compound aircraft. That is, it has certain properties of of flight in certain operational modes. I.E. vertical takeoffs and landings like a helicopter with power to the rotor system and cruise operation like a gyroplane, non-powered rotor. The gyrodyne was powered with a 525 hp engine that could transfer power to the anti-torque propeller and three bladed rotor. The ship set a world speed record in 1948 travelling at a speed of 124 mph. A second type was highly modified with jets on the rotor tips and first flown in 1954.

Fairey didn't stop there, development lead to a large transport based on the operational aspects learned from the Jet Gyrodyne. The new transport was designated the Fairey Rotodyne. This was definately a large compound aircraft, capable of carrying 40 passengers and a gross weight of 33,000 pounds. The four bladed rotor had a 101 feet eight inch diameter equipped with compressed air jets at the rotor tips. The spacious interior and high cruise speed of 185 mph generated much intrest in the design. The Rotodyne first flew in 1957 and on 5 January 1959 set a world record for rotary wing aircraft with a speed of 191 mph. The Royal Air Force and several commercial operators sought to exploit the design capabilities but problems aroused by noise from the tip jets and other issues within the British aeronautical industry prevented Fairey from full-scale production and the design was cancelled in 1962.

1949, France. Louis and Jacques Breguet are among the worlds most famous aircraft manufacturers but few know of their rotorcraft work. We diverse here a bit but stay with me. Louis produced one of the first helicopters in 1908 and the craft was actually able to break ground. After World War II the company, Societe Avions concentrated again on helicopters. In 1949, Louis produced his third helicopter with good market prospects and a fast cruise of 125 mph but never got beyond the prototype due to lack of funds. What is interesting here is all of Louis Breguet's helicopters were designated "Breguet Gyroplanes".

1950's/1960's, United States. Aircraft Manufacturers McDonnell and Bell started research on compound aircraft. McDonnell's prototype designated XV-1 was the genius of Austrian pioneer Friedrich von Doblhoff. First flown in 1954 this four-place pusher propeller design featured tip nozzles. In October of 1956 this incredible little ship became the first rotorcraft to reach a speed of 199 mph. Development was discontinued in 1957.

Bell took a different approach with the XV-3 convertiplane in 1955. Continued development of this technology has resulted in current application of the V-22 Osprey and 609 respectively.

Rotorcraft development had definately shifted to helicopter research especially after these compound test aircraft. The large manufacturers were designing new designs and incorporating the new turbine engines, which would bring the true life to the helicopters capabilities. If it had not been the for the accomplishments and fortitude of smaller companies to produce gyroplanes in a difficult marketplace the gyroplane may have disappeared and become a lost technology all together.

1960, The Umbaugh two place autogyro is produced in conjunction with the Fairchild Airplane Company High success of the design was expected but higher than expected production costs following the building of the intial two prototypes found restricted sales. (Note: Umbaugh/Umbaugh Company(USA)became involved in helicopter construction in the late 1950's and built the Umbaugh 18 autogyro with the Fairchild Engine and Airplane Company.)

May 28, 1965. Air and Space recieves FAA type certification approval for its gyroplane and delivers the first production model to a Mr. Willis Star.This type certificated gyroplane see higher than expected build cost and it too will have limited sales.

1960, Canada. The Avian Aircraft Ltd. Founded in 1959 by Peter Payne from inception on concentrating on the design and construction of helicopters and autogyros. Avian unviels a small two-seat gyroplane in 1960 known as the Avian 2/180 Gyroplane with a ducted pusher propeller. As improvements were incorporated into the design the type was granted Civil Approval in 1967. Like the Umbaugh, high costs prevented further development.

1969, Great Britian. A small company founded by Wing-Commander K.H. Wallis called Wallis Autogyros Ltd. in 1961. Mr. Wallis wasted no time, flying his first autogyro in August of 1961. Building nine variants of single place autogyros, construction of a two-place type was started in 1969. Testing was then begun with a four bladed rotor and produced as the Wallis WA-116F.

Wing Commander Wallis flew the WA-116F on a closed circuit course and set a world speed record in 1974 travelling 416.48 miles. Wallis autogyros vary in powerplants from 72 to 160 hp. These gyroplanes have been employed in variuos mission roles from James Bond movies to research with Sperry Radar.

1971, United States. The Bensen Aircraft Corporation has been the largest manufacturer of light gyroplanes, available in kit form since the fifties. The Bensen B-8M single place gyroplane made its debut in 1971 with a 72 hp McCulloch engine, overhead control bar and tubular frame construction. This open cockpit design has inspired and trained many gyronauts over the years. Prior to and since the passing of Dr. Bensen an annual gyroplane fly-in in his honor is held in Wachula Florida.

1980, Spain. AISA- Aeronautica Industrial S.A. a company founded in 1923 with previous building experience on Cierva autogiros, set out designing its own autogyro. The design was intended for civil use with greater capacity than designs that were currently being offered by the United States and Great Britian. A Lycoming LO-540 powers the AISA Autogyro GN with a four bladed articulated rotor. The cabin is a four place design with access from both sides of the fuselage. Stub wings support twin booms and dual vertical stabilizers. Max spped is 150 mph.

1980's Kits. Outside of Bensen, Ken Brock with Brock Gyrocopter offered plans and kits for the gyroplane he regularly flew at airshows. His demonstrations showed the aviation world the versatility of the gyroplane and his kits helped more individuals build their own aircraft. Since the 80's many more kit manufacturer's have joined the ranks and offer a variety of styles that have provided the gyroplane adventure for new generations.

1990's United States. CarterCopter by Jay Carter Jr.. Mr. Carter envisioned greater rotorcraft potential by unloading the rotor system at higher airspeeds. The concept was not revolutionary but the means to do it was. By using new materials to create a high inertia rotor capable of providing a MU factor of one. An accomplishment not even achieved in helicopter design. The result is an experimental research vehile of gyroplane design called the CarterCopter. The aircraft has reached it's goal of MU1 but unfortunately the program has suffered several mishaps in landing situations with the ultimate loss of the aircraft. The reseach, technology and talent as well as motivation to develop a production version lays on the horizon for Jay. Carter needs what other gyroplane companies in the past needed-funding.

Present Kits. The modern gyroplane typically is a homebuilt of experimental nature and is available in kit or plans form. The modern gyroplane kit is a simple, safe and effective way to mass produce the gyroplpane on a semi-large scale. The kits can be found in open cockpit or enclosed cabin designs. Check out the designs on the Kits page or Kit Selection page.

The preceding information has highlighted some of the grander points in gyroplane development and it is hoped that this information wetted your appetite and intrest to further research. Certainly there have been manufacturers in many other countries with many unique designs.

The Hofstra University has some great historical data on gyroplane historythat you may find interesting.

Historic Gyroplane Aviators

Aviation Historic posters and prints

Historic Gyroplanes

In support of aviation history, the State of Florida has a very rich history. A part of that history was the first regularly scheduled passenger airline. In 1914, Mr. Tony Jannus flew from St. Petersburg to Tampa in a Benoist biplane.

2014 will mark the centennial of birth of the commercial aviation industry. Plans are under way to mark this historic event. Www.gyroplanepassion.com is proud to support the efforts of the Florida Aviation Historical Society and the Flight 2014 project.

To learn more or give your support of the event follow the links below...

Florida Aviation Historical Society

Flight 2014

History of Gyroplanes

Excerpt From

Autogiro to Gyroplane: 1923 - 2003

Dr. Bruce H. Charnov Ph.D. J.D.

Hofstra University

Juan de la Cierva was born in Murcia, Spain on September 21, 1895, and by 1908-9, had decided to make aviation his career. In 1911 he enrolled at the Civil Engineering College of Madrid (Caminos, Canales y Puertos) and in 1912 with his friends "Pepe" Barcala and Pablo Diaz constructed the first Spanish airplane, the BCD-I, known as "EI Cangrejo" - the "Red Crab", becoming the "Father of Spanish Aviation."

In 1919 Cierva produced a large three-engine bomber that, piloted by Captain Julio Rios Argiieso, crashed in its initial flight when the aircraft stalled. Pondering the crash, Cierva's brilliant insight was to see the wing differently ---aircraft stalled when the air passing over the wing failed to generate enough lift at slow speed - he reasoned that stall could be effectively eliminated if the wing itself moved independently of the aircraft. The rotor, a moving, stall-proof wing, was placed on top of a fuselage. He patented the name" Autogiro" and it flew by autorotation, "the process of producing lift with freely-rotating aerofoils by means of the aerodynamic forces resulting from an upward flow of air." As long as the Autogiro was propelled forward, air coming up through the rotor would generate lift, and should the Autogiro's motor fail, it would gently descend while air flow upward through the rotor blades.

Between 1920 - 23 Cierva progressively developed autorotation in the C.1, C.2 and C.3, but it would be his forth model that would finally conqueror the air. Cierva stated that the first flight of his CA Autogiro was on January 9, 1923 at Getafe airfield outside Madrid when ( Calvary) Lieutenant Alejandro G6mez Spencer guided the craft in taxi tests during which the craft became airborne. But most historians maintain that the first observed (and filmed) flight of C.4 took place on January 17, 1923 when G6mez Spencer flew 600 ft at a steady height of 13 ft across the field. Transferring operations to England in 1925 and forming Cierva Autogiro Ltd. on March 24,1926 with prominent Scottish industrialist James G. Weir, his brother Viscount William Weir of Eastwood and Sir Robert M. Kindersley, Cierva continued to improve the Autogiro and in early 1929 licensed the technology and rights to his patents to Harold Frederick Pitcairn of Bryn Athyn, P A.

The youngest son of John Pitcairn, co-founder of Pittsburgh Plate Glass Company, Harold was born in 1897 and took an early interest in aviation. Inspired by the first flight of the Wright brothers in 1903, he began flight training as an air cadet in the last days of WWI, and would eventually earn a pilot's license signed by Orville Wright. Pitcairn and Agnew Larsen, who he had met in pilot training, produced the classic Mailwing airmail series, but it was the Autogiro that fired their passion. In 1928 Pitcairn ordered a Cierva C.8W (the W was for the American Wright Whirlwind engine), which arrived at Pitcairn Field, Willow Grove, PA and on December 18, 1928 made the first rotary-wing flight in America piloted by Cierva pilot H. C. A. "Dizzy" Rawson, followed the next day by Pitcairn.

In early 1929, Cierva and Pitcairn negotiators agreed that the Pitcairn-Cierva Autogiro Company (PCA) would be formed in America with the rights to license Cierva's patents. Pitcairn threw himself into the development and promotion of the Autogiro - and the results of the next 16 months would earn him and his associates the Collier Trophy for the greatest aviation achievement for 1930. Pitcairn had refined Autogiro development, first learning from the C8W (which was presented to the Smithsonian on July 22, 1931), then with a series of developmental aircraft, the PCA-I, 1A and lB. (The PCA-1A is currently exhibited at the American Helicopter Museum & Education Center at the Brandywine Airport, West Chester, PA on loan from the Smithsonian). But it was the next aircraft, the PCA-2, that captivated America. An original design the PCA-2 was seen over major American cities in late 1930-early 1931 in its certification flights to much publicity and acclaim. It innovated with a clutched gearbox that briefly transmitted power to prerotate the rotor to greatly shorten the takeoff run. It would prove a crucial contribution to Autogiro development.

Cierva developed progressively more sophisticated designs with a means to tilt the rotor head and altering the pitch (angle) of each individual rotor blade, called collective and cyclic control, and, making use of Pitcairn's prerotator, achieved a "jump takeoff" capacity with the C19MkIV in 1931-32 The rotor would be spun up at zero pitch and then "snapped" into a positive angle, causing the aircraft to "jump" into air, an ability developed by Pitcairn the next year in the developmental PA-22 Autogiro. But both inventors realized that this was only a partial step in realizing the Autogiro's potential, for a significant problem remained. Even though the Autogiro could takeoff and land vertically, the wing-based control surfaces lost effectiveness at slow landing speeds. Cierva's C30 series and Pitcairn's PA-22 and Luscombe-built aluminum body PA-36, and the KD-1 series constructed by Kellett Autogiro Company of Philadelphia were engineering marvels capable of jump take-offs and direct-control without wings. But this came too late to save the Autogiro, for the world's attention was riveted on the stunning indoor demonstrations of the Focke-Achgelis Fa-61 helicopter by Hanna Reitsch in 1938.

Cierva died in the crash of a KLM DC-2 bound for Amsterdam from the airport at Croydon Aerodrome, London on December 9, 1936. Stripped of his passion, the Cierva Autogiro Company, under the engineering leadership of Dr. J.A.J. Bennett, would shift the focus of its efforts towards developing a helicopter; and even though Cierva-licensed Autogiros would be used by the British, French, Russian and Japanese forces, the Autogiro would all but disappear by the end of WWII. Few would know or remember that it was the English Cierva Rota C.30A Autogiros that would daily calibrate the coastal radars that enabled the RAF to defeat the German Luftwaffe and win the Battle of Britain. The Japanese Kellett-licensed Kayaba Ka-1A Autogiro series had virtually no impact on the war and the Russian TsAGI A7 Autogyro (not built under a Cierva license, hence not an Augtogiro), the first such aircraft specifically constructed for combat operations, faded before the might of the German onslaught as did the French aircraft built by Liore-et-Oliver and SNCASE.

Almost no one remembers the obscure British Armed Forces Experimental Establishment Malcolm Rotaplane or Rotabuggy, a modified Willys 1/4 ton "four-by-four" military truck with a seesaw "teetering" rotor and attached aircraft control surfaces. Perhaps the most ungainly flying craft ever, it was towed successfully to 1,700 ft. And even less well-known was "Project Skywards", a parallel wartime attempt in Australia to develop a flying jeep ("Fleep").

The most familiar of the WWII autorotational developments were, paradoxically, the most insubstantial, the English and German rotary kites. The Focke-Achgelis FA-330, launched from German submarines at the end of a 400 ft tether to increase target observation, is found in more museums than any other comparable craft only because the Allies captured the factory, but few of the 1943 English Rotachutes designed by Raoul Hafner survive, a one-person giro-glider designed to insert secret agents into occupied Europe from airplanes with a precision gained from use of a two-bladed teetering rotorhead that could be controlled by means of a hanging-stick control.

And so by the end of WWII the Autogiro had effectively disappeared. Pitcairn had surrendered his airfield to the military for wartime use and had the prototype PA-36 aluminum bodies cut up for scrape to aid the war effort. Kellett had renamed itself the Kellett Aircraft Company and what was left of Pitcairn's manufacturing company, becoming briefly the Firestone Glider & Autogiro Company, was effectively out of the business. The other American licensee, the Buhl Aircraft Company, had developed a single model but failed to survive the Depression. And the attempts by Philadelphia�s E. Burke Wilford, making use of patents of Germans Walter Rieseler and Walter Kreiser (rigid rotors with control achieved by means of cyclic pitch variation) had not gained engineering acceptance. And perhaps the most intriguing autorotational experiments, the pioneering convertiplane combination of a gyroplane and fixed-wing aircraft of Gerard P. Herrick ended in 1942, but not before successful mid-air conversions by test pilot George Townson in 1937 (that aircraft, the Herrick HV-2A is stored at the Paul Garber Center, Silver Hill, MD). In 1945 Dick Haymes may have crooned to Helen Forrest in I'll Buy That Dream that "we can honeymoon in Cairo in our brand new Autogiro" but there were no new Autogiros - it seemed certain that Cierva's vision would merely be a minor footnote to helicopter development, but it did survive -- it came down to a single Rotachute and a Russian immigrant - Igor Bensen. Although Harris Woods would design and fly a giro-glider in 1945, a development unknown to Bensen and forgotten by history, the popular future of autorotation lay with the charismatic, passionate Russian!

Igor Bensen, born in 1917, was the son of a Russian agricultural scientist, Basil Mitrophan and Alexandra P. Bensen. His father was posted to Czechoslovakia in 1917 at the beginning of the Russian Revolution while the rest of the family remained behind. The Russian civil war lead to harsh times, and the Bensen family was soon reunited in Prague, far from the turmoil. At 17 Bensen was sent to the University of Louvain in Belgium, from which he received a B.S. degree.

Bensen accepted a scholarship from the Stevens Institute in New Jersey in 1937 to study mechanical engineering, graduating with honors in 1940. As an alien Bensen had been forced to turn down a job offer to work for Igor Sikorsky, and his first job was as an engineer with General Electric at the age of 23. General Electric executives took notice of Bensen's interest and assigned the young engineer to the company's helicopter development efforts.

While working on the project, Bensen flew a salvaged Kellett XR-3 in 1943, and eventually gained almost exclusive use of the surplus Autogiro. Bensen became a highly skilled Autogiro pilot, and gained a deep understanding of the dynamics and theory of autorotational flight. The USAAF had received some of the recovered FA-330 rotary kites and were experimenting with pilot George Townson, as well as a Hafner Rotachute and Bensen asked his boss to acquire the Rotachute for evaluation. The military agreed to loan the Rotachute providing that General Electric agreed not to fly it.

Bensen ignored the military's requirements and personally flew the Rotchute in tow, and launched it from the bomb rack of the XR-3. Those tests lead to the Bensen B-1, an amateur-built 120 Ib giro-glider capable of carrying a 300 Ib load, differing from thee Rotachute with the addition of nose and tail wheels, a semi-rigid rotor in place of the Rotachute's individual flapping rotor blades, and a control stick 'reverser' to allow more effective direct-control of the rotor. The crash of the B-1 led directly to the B-2 which was of an all-metal construction. The B-2 lead to the G-E Gyro-Glider in November, 1946 but little came of the G-E model. And subsequently in Schenectady, the Helicraft Equipment Company developed a 60 Ib variant of the Rotachute called the Heli-glider in 1949. An extremely simple design that flew with a 14 ft rotor that achieved 550 rpm, the lack of weight made it difficult to fly with an overhead stick control, and the project was soon abandoned.

Benson, now firmly committed to rotary flight development, joined Kaman Aircraft in 1951 where he organized and directed the research department and flew Air Force and Navy helicopters. After two years, borrowing money from his brother, Bensen left to found his own company in Raleigh, NC.

In 1953 Bensen Aircraft Corporation introduced the B-5 Gyro-Glider, a single-seat rotary--kite towed in back of a vehicle and deriving its lift from an unpowered rotor. It featured a light tubular aluminum frame resembling a cross with two pieces, a longer keel crossed by a shorter perpendicular section. A lightweight aluminum-frame web set was attached to both the keel and a reinforced metal mast extending upward from the keel. Control was initially achieved with a hanging stick control attached directly to the rotor hub that was positioned on top of the mast with a two-blade rotor. A nose wheel was attached directly to the front of the keel while landing wheels were affixed to each end of the perpendicular crosspiece. The keel, in back of he seat and mast, carried a plywood fin and rudder much as had the Rotachute. It flew well when towed by even a small automobile and did not require any license, and was relatively safe. It was also distinguished by ease of construction and the builder could either purchase a kit or build from plans. The materials were readily obtained and fabrication could be completed by the moderately skilled in 3-4 weeks. It would become the home-built B-6, and the prototype was accepted into the Smithsonian's NASM on July 22, 1965.

Bensen subsequently developed a Reynolds aluminum prototype, the B-7 Gyro-gilder which flew on June 17, 1955. From B-7 .came the B-7M (for motorized) which first flew on December 6,1955 with Bensen as pilot and Charles "Charlie" Elrod and Tim Johnson as ground crew. It weighed 188 lb. as the airframe was made of rounded aluminum tubing and had a wooden propeller attached to a 42 hp Nelson two-stroke engine, with the wooden rotor attached to a spindle type tilting head cyclic pitch rotor with a hanging control stick. Bensen called his Rotachute-derived creation a Gyrocopter, a term he subsequently trademarked. After three days of successful flight testing the B-7M crashed as its pressurized fuel tank failed. Bensen, a highly experienced Autogiro pilot, set the aircraft down in woods adjacent to his NC factory. He later ascribed the safe landing to "much luck and the good Lord's will." The B-7M, rebuilt in three days, was flying by December 17, 1955, a particularly moving experience for Benson as that was the 52nd anniversary of the Wright brothers first powered flight.. Ever aeronautical engineer and pragmatic scientist, Bensen relentlessly analyzed the flight performance of the B-7M, particularly those factors that had led to the accident, and the result was an improved control linkage to the rotor head.

The subsequent B-8M model, incorporating the improvements developed and tested in the B-7M, powered by a more powerful 72 hp McCulloch two-stroke piston engine that had been used on drones for the military, was placed into production in 1957 and became the most produced and copied aircraft design in history and provided, in kit form and plan-built, the most popular way to fly. The "Spirit of Kitty Hawk", a B-8M Gyrocopter in which Bensen had personally duplicated the Wright brothers historic first flight at Kitty Hawk on December 17, 1966, and with which he had set twelve world and national Gyrocopter speed, distance and altitude records between May 1967 and June 1968, was accepted into the Smithsonian Institution aviation collection on May 14, 1969. The Bensen, and its variants and local adaptation was to dominate the American Gyrocopter movement for almost twenty-five years.

In Europe, however, it was a different story. England's Wing Commander Kenneth H. Wallis, Scotland's Jim Montgomerie in and Finland's Jukka Tervamaki began with Bensen kits or plans, but soon modified the design, taking gyrocopter design into some very un-Bensen-like directions. Wallis, who would achieve international fame with "Little Nellie", a WA-116 autogyro, in the 1967 James Bond film You Only Live Twice, remains an honored pilot, world record holder and designer, while Tervamaki did pioneering work with composite materials (fuselage and rotor blades) and was the most significant influence on Italy's premier designer/ manufacturer Vittorio Magni.

 

But all mid-century-on attempts to revive the Autogiro failed - in 1959-60 Kellett attempted bring its aircraft back for agricultural uses to no avail, and the Pitcairn license of its 1936 AC-35 "Rotadable" Autogiro, capable of driving down the highway at 25-30 mph (stored today at the NASM Paul Garber facility) by Indiana's Skyway Engineering got no further than a prototype in the early 1960s. The most ambitious realization of Cierva's vision, the Fairey Rotodye produced under the initial direction of Dr. J.A.J. Bennett and Captain A. Graham Forsyth, flew between 1957 -1962 until cancelled by the British government in its "rationalization of the helicopter industry". The Rotodyne, a convertiplane making use of four 50 ft steel jet-tipped rotors, could take off and land as a helicopter and fly as a gyroplane carrying 42 persons at 200 mph - in 1957 with a perfect safety record. In order to conceal the amount of its funding, the only model was ordered destroyed by the British government and all that remains of this incredible aircraft are a few parts in a museum, photographs and films - had it gone into production and the USMC pursued its interest, the military might have acquired an effective vertical/ fixed-wing combination that even now remains unrealized. And the Kamov Ka-22 (The "Russian Rotodyne"), known in the Soviet Union as the Vintokrulya (Vintokryl) ("Screw Wing"), and dubbed "Hoop" by NATO, also failed to gain government acceptance after several crashes. And the Umbaugh (later Air & Space) 18A, Avian 2/180 and McCulloch J-2 2/3 place gyroplanes failed to achieve commercial acceptance despite technical sophistication and the enthusiastic belief of their backers that the world needed a gyroplane. In general, all that remained of Cierva and Pitcairn's autorotational vision were the thousands of amateur-built Gyrocopters and their variants.

        Bensen and his associates would in 1962 found the Popular Rotorcraft Association (PRA), which even today remains the world's preeminent Autogiro / auto gyro / Gyrocopter / gyroplane organization. Bensen declared in 1970 somewhat unfairly that Ken Brock had so modified the design that it could not no longer be called a Gyrocopter - Brock then called his KB2 a "gyroplane." Under Brock's presidency of the PRA (1972 -1987) gyroplane design flourished. The most notable of the new designers was Californian Martin Hollmann. His major contributions include the Sportster, the world's first successful two-seat amateur-built gyroplane trainer in 1972, and the first "ultralight" gyro plane, the "Bumble Bee", in 1983. Also significant was Bill Parsons two-seat Trainer, a Bensen B-8M with a longer keel to accommodate a second seat, dual controls and a rotor head attached by an upside-down "u" shaped tandem double mast. But it was only at the start of a new century that the Autogiro was to become the gyroplane.

Groen Brothers Aviation, headed by brothers David and Jay Groen, has developed a family of larger Hawk 4 gyroplanes targeted to the agricultural, law enforcement, package delivery and passenger shuttle service markets. Time magazine, in its November 19, 2001 issue, named the Hawk 4 as one of the best "Inventions of the Year."

The Utah Olympic Public Safety Command (UOPSC) made use of a Hawk 4 during the 2002 Olympics with a FLIR Systems, Inc. day / night observation system, a Spectrolab Inc. SX-5 search light, an Avalex Technologies flat panel display, a Broadcast Microwave Services realtime video downlink system and a law enforcement communications radio stack. GBA had succeeded in defining a reconnaissance mission where Cierva, Pitcairn, Kellett, the French, English, Germans, Russians, Japanese and even Ken Wallis had failed. Given the enthusiastic reception of the Hawk series of gyroplanes, the business acumen of the Groen brothers and their associates, it is likely that they will be successful and the Autogiro, in its newest gyroplane configurations, will achieve an acceptance that has been elusive since the PCA-2 and C.30A flew over American and European skies.

 

Groen Brothers Aviation extends their gratitude to

Dr. Bruce H. Charnov for permission to share

the proceeding excerpt from his informative

book �From Autogiro to Gyroplane.�

Bensen X-25A "Gyrocopter"

The gyroplane (or "gyrocopter" or simply "gyro") is a helicopter-airplane hybrid, offering many of the benefits of both and several of its own. Unlike a helicopter, the gyro's rotor blades are unpowered, necessitating a short roll for take-off. A major safety feature of the gyro is that if the engine fails, the craft can glide to a safe landing. Also, the gyro is less affected by high wind than typical fixed-wing aircraft and is not subject to stall. History was made in 1924 when Lt. Juan Gomez-Spencer made a flight in the world's first practical rotary-wing aircraft - the Cierva C.4. Pre-war autogiros (autogiro was a Cierva trade name) were massive aircraft that were expensive to purchase and operate, but they had considerable success in specialized roles such as mail delivery to central cities, news reporting, and the air-show circuit.

In the 1950s the Bensen Aircraft Corporation developed the novel "Gyrocopters" and "Gyrogliders." The B-7 Gyroglider, introduced in 1955, captured the public's imagination with its unprecedented simplicity of design and ease of flight. Although the B-7 had no engine and was towed into the air very much like a kite, shortly thereafter the engine-powered B-7M Gyrocopter was introduced. Bensen founded the Popular Rotorcraft Association in the 60's and his aircraft dominated the home-built rotorcraft movement into the early 1980's. The Bensen X-25 Discretionary Descent Vehicle [DRV], a revised version of the Bensen Aircraft standard B-8M gyrocopter, was tested as means for downed flyers to escape from enemy territory. The concept called for replacing the standard ejection seat with the DRV, which would enable a pilot forced to eject to fly away from the action in a controlled descent. Designed to operate like a rotorchute, following ejection and a brief period of decent, the DDVs rotor blades automatically self deployed and aerodynamic forces then rotated the blades. It came about as a result of a growing number of pilots being downed beyond the range of conventional rescue methods during the Vietnam War.

The basic X-25 was un-powered and of very basic construction, consisting of little more than an aluminium square cross sectioned structure with a single seat and four post landing gear. The X-25A & B were variations of Bensons McCulloch powered B-8M and un-powered B-8 Gyroglider. Although far more complex than the planned �one use� DDV, the X-25A and B provided both the data required to prove the feasibility of the DDV concept. The X-25A first flew in May 1968 and was proven to be feasible, but production was never funded.

 A SHORT HISTORY

If we except Leonardo da Vinci drawings, the history of rotary wings goes way back. In 1784, Launois and Bienvenue, two French physicians, presented to Paris Academy of Science the model of "a device with propeller that could fly". On August 21, 1907, the Breguet brothers and professor Richet would test the first 4-rotor aircraft, that was able to hoover 1 meter above the ground. Sure, it could not really fly... yet !

Just after the first World war, a few pilots found that flying these strange fixed-wings machines could be somewhat dangerous, due to their incredible ability to stall and to kill their pilots.

Some of them decided to research aircrafts that could not stall at all - therefore making flight safer. We could name there in France Henri Mignet, whose "living wing" would prove to be a safe concept for conventional aircrafts.

But, in parallel, in Spain, Juan de la Cierva took another direction: he believed that a "rotating wing" would do the trick. And it did, indeed ! Juan would become, after many trials and prototypes, the founder of the gyrocopter aircraft category. He would cross the Channel in flight in 1928.

Cierva C-4                               January 9, 1923 C-4 flight                        Juan de la Cierva

                                                                                                            (1895 - 1936)

                                          


Development of the gyrocopter continued between the two wars, both in Europe and the USA. During WWII - an often forgotten history - they saw active duty, for instance as the mean for calibrating British radars, or as trailed observers on German submarines.

In parallel, the development of the helicopter, which did not saw anything really flying until 1937, continued as well.

Mainly for psychological reasons, the helicopter would then take over the gyrocopter for a good decade - military and civils alike not really understanding how a free-rotating rotor could, much more safely than a powered one, ensure the sustentation of an aircraft.

Once past de difficult 1950's, when people started again to think about leisure and pleasure, the gyrocopter came back into further development. From the 60's to the 80's, the main improvements came from the USA, then from Europe, mainly Finland, Italy and France. Strangely, Spain somewhat forgot that De la Cierva was the finder of this aircraft.

In the meantime, many projects had been tried, ranging from leisure to transport gyrocopters. For transportation, none succeeded so far, such as the British Fairey Rotodyne. But more recent gyrocopters may change this with the time. The Groen Hawk 4 served during the Olympic games as observer, and the Carter Copter continues its development, and represents today the most advanced gyrocopter ever made with performances hard to match. Today, many official entitites use light gyrocopters in several countries.

Fairey Rotodyne                                 Groen Hawk 4                              Carter Copter

                     

The main use today of gyrocopters lies in the leisure market. Tens of thousands of pilots enjoy flying these rotating wings. The researches have made them extremely secure to fly, as these are the only aircrafts (except helicopters) that can safely land without engine on a place barely exceeding their length.

GYROCOPTER vs. HELICOPTER

One of the most difficult part to understand is how the gyrocopter differs from the helicopter. Basically, the gyrocopter has a simpler construction than the helicopter, with a simplified rotor.

On an helicopter, the rotor is powered, and ensures both lift and propulsion. The helicopter rotor is simply acting as a big variable-pitch propeller. As such, the air attacks the rotor from above, giving it its "nose down" attitude in flight (exaggerated in the drawing for demonstration purposes). The powered rotor accelerates the air mass towards the ground.


Flash animation: helicopter vs. gyrocopter

On a gyrocopter, the rotor is free (unpowered), and only ensures the lift. Propulsion is ensured by a conventional tractive or propulsive propeller. The air attacks the rotor from below, giving a slight "nose up" attitude. By fleeing trough the rotor, the air maintain its permanent rotation. This is a complex phenomenon too long to describe here.

This is known as autorotation. In an helicopter, autorotation only happens when engine quits. In a gyrocopter, autorotation is permanent, it is its natural way of flying, with our without engine.

To start the autorotation phenomenon, a gyrocopter will, when stopped on the ground before take-off, prerotates its rotor, until it reaches sufficient RPMs to ensure lift after a short roll. After that... it is automatic, and the relative wind / weight combination will ensure permanent rotation - therefore lift - for the aircraft, rotor RPMs varying automatically as needed to maintain the needed lift along all phases of the flight.

So the main differences between gyrocopters and other aircraft kinds are the following, for the same MTOW:

GYROCOPTER

HELICOPTER

FIXED WINGS / TRIKES

Cannot hoover

Can hoover

Don't try to hoover

Cannot take-off vertically

Can take-off vertically

Cannot take-off vertically

Cannot land purely vertically

Can land vertically

Cannot land vertically

 

Needs very short take-off strip

Take-off strip not needed

Needs a take-off strip

Needs its length to land

Needs its length to land

Needs a landing strip

 

Very little sensibility to turbulences

Medium sensibility to turbulences

Sensible to turbulences

Larger flight envelope than fixed wings

Larger flight envelope than fixed wings

Limited flight envelope

 

Easy to pilot

Complex to pilot

Rather easy to pilot

Excellent manoeuvrability

Superior manoeuvrability

Average manoeuvrability

 

Easy for maintenance

Relatively heavy maintenance

Relatively easy for maintenance

 

Less expensive than helicopter

Rather expensive

Slightly less expensive than gyrocopter

Needs more power than fixed-wing / trikes

Needs a lot of power

Needs less power than gyrocopter

From this comparison, it is easy to extract that, where the specific hoover and take-off capabilities of an helicopter are not needed, a gyrocopter will do the same job at only a fraction of the expense. Gyrocopter excel in the watch and camera-plateform areas, at a much lower cost than helicopters. And of course as leisure aircrafts.

The increase of power needed by the gyrocopter compared to fixed-wings / trikes comes from the fact that the free rotating rotor generates about 70% of the total drag of the aircraft - this being compensated by more power, only really needed for the take-off part of the flight.

The private gyrocopter pilot will enjoy very quiet ride in turbulent conditions, and will fly when his mates are stuck in the airfield's bar due to strong winds, with a manoeuvrability comparable to the one of an helicopter. A light two-seater gyrocopter can usually fly as slow as 40 km/h, and in excess of 160 km/h.

Of course, comparing gyrocopters to fixed-wings or trikes is difficult, as this is really a matter of taste: some prefer rotary wings, other prefer fixed- or flex-wings.

All what we can say is: if you have never tried it, just try with a professional gyrocopter instructor. You may find it addictive.

PILOTING A GYROCOPTER

In the table above, we state that piloting is easy. This in no way means that you can sit in one, and just take-off ! Just like with any other aircraft, you will have to take lessons, and learn to pilot it. Depending on your country, your Civil Aviation Authorities may request more than what we hint below.

But, due to the fact that the gyrocopter's controls are basically identical and often simpler than those of a conventional fixed-wing aircraft, a fixed-wing pilot will usually need something like 10 hours dual training to convert to gyrocopter. Someone with no prior flight experience will need the same amount of time as he would for learning to pilot a fixed-wing aircraft.

We now suggest that you take a deeper look at our Phenix, an aircraft manufactured in De la Cierva country, and a credit to his spirit.

Autogiros, Gyroplanes, & Gyrocopters

v1.0.1 / 01 dec 08 / greg goebel / public domain

* The helicopter was not the first successful rotorcraft, that honor going to the "autogiro", invented by Juan de la Cierva of Spain in the 1920s. Although there was considerable enthusiasm over the concept in the 1930s, the development of helicopters during World War II ended work on "gyroplanes", as autogiros are now known, for serious aviation roles, though they have thrived in the hobbyist market, and some companies believe that the concept has unused potential. This document gives a brief history and description of the autogiro / gyroplane.


[1] JUAN DE LA CIERVA'S AUTOGIROS
[2] THE BENSEN & WALLIS GRYOPLANES
[3] THE FAIREY ROTODYNE
[4] GROEN BROTHERS GYROPLANES
[5] COMMENTS, SOURCES, & REVISION HISTORY


[1] JUAN DE LA CIERVA'S AUTOGIROS

* Experiments with piloted rotary-wing machines went back to before the First World War, when the Frenchmen Paul Cornu and Louis Breguet, the Ukrainian Igor Sikorsky, and others built helicopters that at best could hop up off the ground, but were not capable of sustained controlled flight.

The first person to build a practical rotorcraft was Juan de la Cierva, who was born in Murcia, Spain in 1895. He acquired an engineering degree and became a pioneer of Spanish aviation, working on various aircraft projects before and into the First World War. In 1919, he was considering the crash of a bomber that had stalled when he came up with the idea of a stall-proof airplane. All he had to do was mount a free-spinning rotor above the airplane, partly or completely replacing the normal fixed wings. In forward flight, the aircraft's engine and propeller would force a draft through the rotor, generating lift -- incidentally resulting in a short takeoff -- and if the engine failed, the spinning rotor would "autorotate", spinning as the machine fell to result in a soft landing. He patented the concept, calling the machine an "autogiro".

Beginning in 1920, Cierva built a series of autogiro demonstrators, beginning with the "C.1", which didn't work. The following "C.2" and "C.3" didn't work either, but his fourth try was the charm, with the "C.4" credited as performing the first recorded successful flight of a rotary-winged machine on 17 January 1923, with Gomez Spencer at the controls. The C.4 was modified from a wartime French Hanriot fighter and still had wings for flight control.

One of the problems that Cierva had encountered with his early machines was "asymmetry of lift". If a rotary-wing machine is moving forward, the rotor blade that's moving forward generates more lift than the rotor blade that's moving backward. The result was that the machine tended to tip over. Cierva's solution was to hinge the rotor blades to the hub, allowing them a degree of travel up-and-down and back-and-forth. Although such a simple scheme sounds like it could have been a disaster, in fact the movement of the blades compensated very well, rising as they moved forward and falling as they moved back. A rotor blade at an upward angle tended to lose lift, balancing the autogiro. He stumbled onto the idea by accident while tinkering with a rubber-band-powered model, fitting the hinged rotor scheme to the C.4.

There were other difficulties to work out, in particular the problem that the fixed wings of the C.4 couldn't control the flight of the aircraft at low speeds, and Cierva hadn't figured out how to obtain flight control with the rotor system yet. He continued his research with the "C.5" of 1923, and then the "C.6 / C.6A / C.6B" of 1924, which was based an Avro 504K fighter. The C.6A was the first of the series to chance a cross-country flight, on 12 December 1924.

In the fall of 1925, Cierva demonstrated the C.6A to the British military, with the British Air Ministry interested enough to order several autogiros for evaluation. They were to be built by Avro; Cierva, backed by a group of British industrialists, decided to set up his own firm, "Cierva Autogiro LTD", in the UK to focus British interest. Along with the construction of two "C.7" autogiros by Jorge Loring in Spain, Avro built a litter of "C.8" series machines with variations in configuration for evaluation. A few were also sold on the export market.

* At this point in the story becomes more complicated as Cierva obtained licensees in a number of countries. Avro stayed with the concept, working on:

  • The "C.9", which was the first autogiro to be built from the ground up instead of being based on an existing aircraft.
  • A floatplane conversion of the C.9 called the "Hydrogiro".
  • The "C.17" series.
  • The "C.19" series, the first real production machines.
  • The two-seat "C.30" series.
  • The side-by-side seating "C.40" series.

A total of almost a hundred C.19, C.30, and C.40 machines were built by Avro, with some operated by the British Royal Air Force under the designations of "Rota Mark I", "Rota Mark IA", and "Rota Mark II" respectively. Some were also sold to the civil or export markets.

In the meantime, Cierva was working with various licensees, one of the most prominent being Harold Pitcairn of Pennsylvania. Pitcairn was an aviation enthusiast from the early days and had taken an interest in Cierva's autogiros, ordering a C.8 and flying it in 1928. It was the first operational rotary-wing aircraft to fly in the United States. Pitcairn's firm, the "Pitcairn-Cierva Autogiro (PCA) Company", gave him a platform to allow him to help refine the design, and soon he was flying a series of developmental aircraft -- beginning with the "PCA-1", followed by the "PCA-1A" and "PCA-1B". It was his fourth machine, the "PCA-2", that really captured public attention by a series of demonstration flights over US cities beginning in late 1931 and continuing into 1932.

The Kellett company of the USA also got into the autogiro business, building a series of "KD-1" machines along the lines of the Cierva C.30, one of which achieved notoriety for being used on an experimental mail run in Washington DC in 1939. Some sources also claim that a Kellett autogiro was taken on an Antarctic expedition by US Navy Admiral Richard Byrd in 1933.

The US Army was interested in autogiros and evaluated a number of Kellett machines from 1935 under the general designation of "YG-1", with the US Army Air Forces (USAAF) following up this effort during 1942 by obtaining a handful of "XO-60 / YO-60" autogiros for the battlefield observation role. The USAAF never put autogiros into combat, however, and though Kellett did modify some of their machines to more powerful "XR-2 / XR-3" prototypes, the company decided to get out of the business.

A number of companies all over the world also built Cierva autogiros:

  • Other British manufacturers built autogiros on a "onesie-twosie" basis, the most interesting being the de Havilland "C.24", which had an enclosed two-seat tandem cockpit and a Gipsy inline engine.
  • A handful of autogryos were built in France, such as the Liore-et-Olivier "C.27", which was derived from the C.19 but had an enclosed cabin.
  • A batch of C.19-type autogiros was built by Focke-Wulf in Germany under the designation of "C.20".
  • The Soviet Central Aerodynamics & Hydrodynamics Research Institute (TsAGI in its Russian acronym) built a series of autogiros, beginning with the "2-EA", which was based on the Cierva C.19 but was not constructed under license. For this reason, some sources refer to them as "autogyros" to distinguish them from true Cierva machines. The 2-EA led to the "A-4", "A-6", "A-7", "A-8", "A-12", "A-13", "A-14", and finally the "A-15", the last of the TsAGI autogiros. None were built in more than small quantities.
  • The Kayaba company of Japan built a over 200 "Ka-1" machines, based on Kellett technology, for the Japanese Imperial Army as artillery spotting platforms. Prototypes of improved "Ka-1A" and "Ka-2" machines were built as well.

* In maturity, the autogiro was a perfectly practical flying machine. Cierva had figured out how to control flight without use of fixed wings, using two innovations. The first was what is now called "cyclic pitch control", in which a set of linkages were used to change the pitch of the blades as they spun around. For example, cyclic pitch control could give a blade a high angle of attack as it moved forward to increase lift, and a low angle of attack as it moved backward, causing the aircraft to shift sideways. Other pitch configurations could be used to allow the autogiro to move forward. The second was what is now known as "collective" control, in which the pitch of all the blades were adjusted equally, with a strong pitch useful for takeoffs and landings and a shallow pitch for forward flight. The same ideas were developed at the same time by Marquis Raul Pateras Pescara, an Argentine working in Europe, and it is unclear if Cierva invented them, but he was certainly the first to incorporate them into a successful flying machine.

Pitcairn added a useful innovation of his own, the "prerotor", which coupled the engine to the rotor while on the ground, allowing the machine to achieve a "jump takeoff" once power was transferred back to the propeller. Cierva had already considered the idea but was using a rope pull starter to get the rotor up to speed.

The two-seat Cierva C.30 / Avro Rota Mark IA makes a good benchmark for the Cierva machines, the C.19 and C.40 being of roughly similar configuration aside from the seating arrangements. It had no wings; a "tadpole"-like tailfin that wrapped around the tail, with a tailplane that ended in auxiliary tailfins; a three-bladed rotor; and tandem open cockpits. It was powered by an Armstrong-Siddeley Civet 1 aircooled radial with 104 kW (140 HP).

   CIERVA C.30 / AVRO ROTA MARK IA:
   _____________________   _________________   _______________________
 
   spec                                      metric                          english
   _____________________   _________________   _______________________
 
   rotor diameter                      11.28 meters              37 feet
   fuselage length                     6.02 meters               19 feet 9 inches
   height                                    3.38 meters               11 feet 1 i nch
 
  empty weight                         555 kilograms             1,220 pounds
   max loaded weight                815 kilograms            1,800 pounds
 
   maximum speed                    175 KPH                      110 MPH / 95 KT
   ceiling                                   2,440 meters              8,000 feet
   range                                    460 kilometers            285 MI / 250 NMI
   _____________________   _________________   _______________________
 

* Although Cierva developed the autogiro into a safe and effective machine, even as the technology appeared to be ready for widespread use, events were conspiring to shoot it down. The first was the death of Cierva in the crash of a Dutch Douglas DC-2 airliner in England on 9 December 1936. The second was the flight of the first unarguably workable helicopter, the German Focke-Achgelis Fa-61, in 1938, making the autogiro seem like a half-measure and focusing work on true helicopters. The third was the outbreak of World War II in the next year, 1939, with industrial development focusing on weapons needed in the conflict.

Autogiros saw very limited use during the war. Avro Rotas were used by the RAF for radar calibration duties, with an autogiro flying from near a radar station to provide a "target" for radar observation. The Japanese pressed their Kayaba machines into service late in the war as antisubmarine warfare platforms, carrying two depth-charges each, making them likely the only autogiros ever to carry a combat load. Some Soviet TsAGI autogiros were used in the observation role during the war with the Germans.

However, by the end of the conflict, helicopter development was going full steam and Cierva's autogiro had become a curiosity at best. The Cierva company survived his death, under the direction of Dr. J.A.J. Bennett, but focused on development of helicopters. It would develop one of the first British-designed helicopters, which would become the "Sanders-Roe Skeeter" after the Cierva company was absorbed by the Sanders-Roe company. Still, Cierva had designed the world's first practical rotorcraft, and had solved a number of problems needed for helicopter development. He would not be forgotten, and work would continue, if at a low and intermittent level on his autogiros -- or "gyroplanes" as they became known in later days to avoid the Cierva trademark name.

[2] THE BENSEN & WALLIS GRYOPLANES

* There was some development of Cierva's ideas during the war, the most prominent being the German Focke-Achgelis "Fa-330 Bachstelze (Wagtail)". It was what as known as a "rotor kite" or "gyrokite" or "gyroglider", which had to be towed into the air since it lacked an engine. It looked a little like an ultralight helicopter, with a metal-tube frame, a standard aircraft tail assembly, and the pilot sitting exposed on a frame seat under a rotor. It had a three-bladed rotor with a diameter of 8.5 meters / 28 feet (7.3 meters / 24 feet in early production), and a total weight of about 72 kilograms (160 pounds).

The Fa-330 was intended to be towed by a submarine to spot targets. A few hundred were built, but it appears they were not put to much use, since German U-boat captains were reluctant to do anything that kept them from diving in a hurry to escape Allied destroyers and sub-hunter aircraft. The Fa-330 was mostly a curiosity in hindsight.

The British developed a gyrokite along much the same lines, developed by an Austrian named Raoul Hafner and called the "Rotachute". It was intended to drop paratroops or agents, but it never went into production. The British then even experimented with light ground vehicles fitted with a rotor for airdropping, but nothing came of that work either. However, the Fa-330 and the Rotachute would contribute to keeping the gyroplane alive over the longer term.

* Igor Bensen had been born to Russian parents in 1917, with his family fleeing the Russian Civil War a few years later. He went to the University of Louvain in Belgium to work towards an engineering degree, obtaining a scholarship for further studies at Stevens Institute in the United States in 1937. He graduated in 1940 and was hired by the General Electric company, which at the time was interested in helicopters and put him to work on the technology.

In 1943, Bensen got the opportunity to fly a Kellett XR-3, becoming a skilled gyroplane pilot. When he found out that the US Army Air Forces had obtained some Fa-330 rotor kites and a Hafner Rotachute, he was intrigued enough to lobby the military for use of the Rotachute -- which he flew himself, though the military had specified that it not be flown. Bensen's investigation led to development of his first gyrokite, the Bensen "B-1". It was of mixed wood-metal construction and abandoned the three-blade flapping rotor system of the Rotachute in favor of a "teetering rotor", a two-blade assembly that tilted to one side or another to deal with asymmetric lift. The B-1 crashed, leading to the all-metal "B-2", which was the basis for a "GE Gyro-Glider" that never reached the market.

In 1951, Bensen joined Kaman Aircraft Company to work on helicopters, but after two years he dropped out to form the "Bensen Aircraft Corporation" in Raleigh, North Carolina, borrowing money from his brother to set up shop. In 1953 he introduced his "B-5" gyro-glider. It could be bought complete, or as the "B-6" in kit form or just as plans. It led in turn by the summer of 1955 to the "B-7" gyro-glider, with the powered "B-7M" -- "M" for "motorized" of course -- with a 31 kW (42 HP) Nelson two-stroke piston engine driving a pusher prop following before the end of the year.

Bensen had suffered a forced but safe landing in the B-7M and did some minor redesign, resulting in the definitive "B-8" gyro-glider and "B-8M" gryoplane -- or "gyrocopter" as he trademarked it. It was in production by 1957, being sold complete, in kit form, or as plans. It would prove a popular ultralight aircraft. In 1962, Bensen helped found the Popular Rotorcraft Association (PRA) to help promote use of ultralight rotorcraft.

The B-8M was built of aluminum tubing, with a two-blade teeter rotor and an overhead cyclic control stick. It was powered by a 54 kW (72 HP) McCulloch two-stroke piston engine and could take off in about 15 meters (50 feet), and land almost vertically through autorotation. The B-8M could taxi fairly well and could be in principle driven on city streets with the rotor tied fore and aft, though despite the existence of publicity shots showing this being done, it seems likely that local police tended to have an opinion on whether this was a good idea or not.

   BENSEN B-8M GYROCOPTER:
   _____________________   _________________   _______________________
 
   spec                                      metric                             english
   _____________________   _________________   _______________________
 
   rotor diameter                      6.10 meters                  50 feet
   fuselage length                     3.45 meters                  11 feet 4 inches
   height                                    1.9 meters                    6 feet 3 inches
 
   empty weight                        112 kilograms                250 pounds
   max loaded weight                225 kilograms               500 pounds
 
   maximum speed                    135 KPH                         85 MPH / 75 KT
   ceiling                                   5,000 meters                 16,500 feet
   range                                    160 kilometers               100 MI / 85 NMI
   endurance                           90 minutes
   _____________________   _________________   _______________________
 

A pontoon-equipped variant, the "B-8MW", was also available. A "B-8V", powered by a Volkswagen flat-four aircooled engine, was offered as well, presumably to appeal to kitbuilders who had their hands on a VW engine. A B-8M and a B-8 were acquired by the US Air Force in 1968 under the designation of "X-25A" and "X-25B" respectively to investigate, ironically, the old Rotachute concept of a controlled parachute, or what the service called the "Discretionary Descent Vehicle (DDV)".

 

Igor Bensen was quite the tinkerer and obtaining a full and accurate list of every flying machine he ever built would be very difficult, but a short list of some of the highlights is interesting enough:

  • The "B-11M" was along the lines of the B-8M except that it was powered by six, count them six, 7.5 kW (10 HP) McCulloch go-kart engines.
  • The "gyro-boat" was just an ordinary small boat with a two-blade rotor that could be towed behind another boat for a low-altitude joyride.
  • Bensen did build a prototype of a true helicopter, a machine with a very general resemblance to the B-8M except for a vee tail and twin contrarotating rotors in an "eggbeater" configuration like that used by Kaman. The Bensen eggbeater didn't go into production.
  • The "B-12 Sky-Mat" was a sort of "flying platform", in the form of a large flat frame with ten rotors arranged around the edge, each driven by a 7.5 kW (10 HP) piston engine. It is hard to figure out what Bensen was thinking, but whatever it was, the Sky-Mat wasn't successful.
  • Bensen also built a "flying platform" named the "Prop-Copter" that looked like a shopping cart with props at each end, but it wasn't successful either.

* The Bensen Aircraft Corporation finally closed its doors in 1986 after over 30 years of existence. The reasons for the company's closure are unclear; there were those who claimed the teeter-bar rotor configuration was dangerously unstable, though the accident rate of the gyrocopter doesn't appear to have been particularly high by the standards of ultralight aircraft -- not in general machines recommended to the faint-hearted. However, the 1980s brought in an age of litigation that helped suppress US private aircraft manufacturers and likely didn't help Bensen's cause.

The company's exit from the marketplace hardly killed off the gyroplane, and in fact many other manufacturers were inspired by Bensen to build gyroplanes of their own. American enthusiasts included as Ken Brock -- who invented the word "gyroplane" in 1970 when Bensen got stuffy about his trademark; Martin Hollmann; and Bill Parsons. Overseas enthusiasts included Jukka Tervmaki of Finland; Vittorio Magni of Italy; Jim Montgomerie of Scotland; and Wing Commander Kenneth H. Wallis of England.

Wallis would become a particular prominent gyroplane enthusiast, setting a series of world records for the class. While some of his machines had a good resemblance to the Bensen B-8M, in development his machines were much more sophisticated in appearance, the best example being the Wallis "WA-116", which had a real fuselage with an open cockpit and an improved rotor system. The prototype performed its first flight in 1961.

In 1967 a WA-116, LITTLE NELLIE, was used in the Sean Connery James Bond move YOU ONLY LIVE TWICE. The gyroplane was fitted with an impressively dubious array of lethal armament -- including heat-seeking missiles that could do a U-turn after being fired forward and attack a pursuer, an impossibility at the time. Wallis did the honors for piloting the machine in the movie. The Wallis designs have proven an inspiration for gyroplane kit makers elsewhere.

[3] THE FAIREY ROTODYNE

* The Bensen gyrocopter and its descendants kept the gyroplane alive, but all efforts to develop more capable machines in the meantime failed. Attempts to revive Pitcairn and Kellett designs went nowhere. However, an attempt to build a large gyroplane, a machine much larger and more capable than anything Cierva ever seriously thought of building, proved impressive, if still a failure in the end.

The Fairey "Rotodyne" was the brainchild of the Cierva company's Dr. Bennett and Captain A. Graham Forsyth. It was a "covertiplane" or "gyrodyne", something like a small airliner with a capacity of 50 passengers, clamshell doors in the rear for cargo loading, twin Napier Eland turboprop engines providing 2,090 kW (2,800 HP) each, stubby wings, twin tailfins, and a four-blade rotor. At takeoff and landing, compressors driven by the turboprops drove air jets out the wingtips of the rotor, with the two compressors each driving two blades of the rotor to provide redundancy, but in forward flight the rotor simply spun freely, as it did in a gyroplane.

Initial work on the concept had been performed from the late 1940s using a series of relatively small "Gyrodyne" demonstrators, leading to the initial flight of the full-scale Rotodyne on 6 November 1957. It was an impressive machine, with a top speed of 320 KPH (200 MPH), and got a lot of press at the time.

   FAIREY ROTODYNE:
   _____________________   _________________   _______________________
 
   spec                                      metric                          english
   _____________________   _________________   _______________________
 
   rotor diameter                      27.43 meters              90 feet
   wingspan                               14.17 meters             46 feet 4 inches
   fuselage length                     17.88 meters             58 feet 7 inches
   height                                    6.76 meters               22 feet 1 inch
 
   empty weight                        10,000 kilograms       22,000 pounds
   max loaded weight                15,000 kilograms       33,000 pounds
 
   cruise speed                          300 KPH                     185 MPH / 160 KT
   ceiling                                    4,000 meters             12,200 feet
   range                                     725 kilometers           450 MI / 390 NMI
   _____________________   _________________   _______________________
 

A license agreement was signed with Kaman Helicopters of the US in 1958. Fairey was swallowed up by Westland the next year, but work was still proceeding on a 75-passenger stretched version powered by twin Rolls-Royce Tyne turboprops. Then the program abruptly ran out steam, with the prototype grounded in 1962 and then scrapped.

The reasons for the cancellation are still argued. The Rotodyne was very noisy, a problem commonly associated with tipjet rotorcraft, but work was underway to deal with the noise problem. The main problem seems to have been that prospective commercial and military buyers didn't materialize as expected, and so the additional development costs for the stretched capable production variant were hard to justify. Some admirers of the Rotodyne suggest that more might have been made of it if the British government had been more enthusiastic about backing the project; that is arguable, but it was an era when the British government seemed to take a perverse pleasure in killing off promising aerospace programs.

* The USSR also built a gyrodyne, the Kamov "Ka-22", in the same class as the Rotodyne, though of considerably different and arguably less elegant appearance. The Soviets called it the "Vintokyrlya (Screw Wing)", while NATO codenamed it "Hoop". It featured a turboprop on each wingtip, driving a forward propeller in flight and a rotor for takeoff; fixed landing gear; and a high-perched canopy to give the flight crew a good field of view. The boxy fuselage was apparently derived from that of the Antonov An-12 turboprop cargolifter.

The project was initiated in late 1954, before the Rotodyne had been completed and showing that the Ka-22 was not a copy of the Rotodyne, as some sources have hinted -- oblivious to the fact that while the two machines were comparable in many ways, they were also clearly different at a detail level. Initial untethered flight of the Ka-22 prototype, fitted with Kuznetsov TV-2VK turboprops, was on 15 August 1959; there were serious control problems, but they were generally resolved in the flight trials program, with a order for three preproduction machines with D-25VK turboprops placed in 1960. The machine was displayed publicly at the Tushino air show near Moscow on 9 July 1961, causing something of a sensation.

The Ka-22 set a number of records for rotorcraft. One of the four Ka-22s crashed on 28 August 1962, killing all seven crew, but the accident was traced to a manufacturing defect, not a design problem, and the program continued up to 12 August 1964, when another Ka-22 crashed, three of the crew surviving and two being killed. Enthusiasm for further work on the machine faded out; it might well have been made into something, but it was complicated, the engine and drive system proving a particular nuisance, and the Mil Mi-6 Hook heavy-lift helicopter seemed to do the job as a heavy-lift rotorcraft. The program was cancelled and advanced derivatives such as the "Ka-34" and "Ka-35" never went beyond the model stage.

[4] GROEN BROTHERS GYROPLANES

* There were other, less spectacular efforts to push gyroplane technology in the 1960s. A pair of two-seat autogiros for the commercial market, the McCulloch J-2 and the Umbaugh U-18A, were designed and received FAA certification, but less than a hundred of each were sold. For the rest of the century, gyroplanes would remain a hobbyist technology, with a number of companies selling them into that market, usually as kits.

While gyroplanes remain alive and well in the domain of hobbyists, so far they have run into a "glass ceiling" for use in general and commercial aviation. Groen Brothers Aviation (GBA) of Salt Lake City, Utah, has been working hard to break through that glass ceiling. For the last few years the company has been promoting the tidy "Hawk 4T" gyroplane, which is definitely in a league above the Bensen B-8M.

The Hawk 4T is a four-seat gyroplane with a two-bladed rotor, is powered by a Rolls-Royce 250 B17C turboshaft engine providing 336 kW (450 HP), and has a payload capacity of 545 kilograms (1,200 pounds). It follows a "Hawk 4" piston-powered demonstrator of similar configuration. As with most modern gyroplanes, the Hawk 4T's engine can spin up the rotor before takeoff, allowing the aircraft to lift off near vertically, and it can also land near vertically by autorotation.

   GBA HAWK 4T:
   _____________________   _________________   _______________________
 
   spec                                      metric                          english
   _____________________   _________________   _______________________
 
   rotor diameter                      12.8 meters                  42 feet
   fuselage length                     7.3 meters                    24 feet
   height                                    4.12 meters                  13 feet 6 inches
   max loaded weight               1,590 kilograms              3,500 pounds
 
   cruise speed                          210 KPH                        132 MPH / 115 KT
   ceiling                                    4,900 meters                 16,000 feet
   range                                     590 kilometers               365 MI / 320 NMI
   _____________________   _________________   _______________________
 

GBA believes the Hawk 4T has an edge because it provides helicopter-like utility at lower cost: gyroplanes can't do some things that helicopters can, in particular hover, but they are in principle cheaper, lighter, simpler, and have greater range and speed. The company feels that other attempts to build gyroplanes for the general and commercial market focused on machines that were too small to be particularly useful. GBA claims the Hawk 4T combines capability with economy, and is targeting civilian applications, particularly in agriculture. GBA realizes that the track record of attempts to revive the gyroplane is not encouraging, and a company official admitted: "We still have to break the credibility barrier."

* While GBA is focusing on the Hawk 4T, the company also produced a neat two-place kit-built gyroplane, the "Sparrowhawk", which is sold through the associated "American Autogyros" company. It is powered by a piston engine, has an enclosed side-by-side seating cockpit, and has proven popular, with enthusiasts making occasional appearances in Sparrowhawks at airshows across the USA.

GBA has other schemes in the works. The company has promoted a gyroplane based on a remodeled Cessna C337 Skymaster, with its rear engine removed, front engine replaced by a Rolls-Royce 250 turboprop, rotor added, wings clipped off, and tail flipped over to ensure rotor clearance. It would have a payload capacity of 900 kilograms (2,000 pounds). A demonstrator, the "Revcon 6A", was flown in 2000.

In addition, the company has promoted concepts for large gyrodynes -- or as GBA refers to them, "heliplanes" -- along the lines of the Fairey Rotodyne, with imagery envisioning conversions of twin-turboprop light cargolifters or even a Lockheed-Martin C-130 Hercules four-turboprop cargolifter, named the "Monsoon", to be used for firefighting. The big Groen gyrodynes are clearly just intriguing paper concepts for the moment, though the company has worked on the design of a combat search and rescue gyroplane for the US Defense Advanced Research Projects Agency. What can be made of GBA's efforts remains to be seen, but it would be hard-hearted not to wish them luck.

[5] COMMENTS, SOURCES, & REVISION HISTORY

* A California company named Sky Windpower has been floating an idea for an interesting application of gyrokites, flying four-rotor systems on an "H"-configuration frame up into the jet stream to generate electric power. It seems like something of a long shot but it's certainly an intriguing idea.

The proliferation of terms in this topic -- autogiros, autogyros, gyrocopters, gyroplanes, helikites, rotorkites, gyrokites, gyrodynes, rotodynes, heliplanes -- is very confusing. I have chosen to focus on the terms "gyrokite", "gyroplane" and "gyrodyne" since as far as I can see neither is trademarked, though gyroplane is a relatively modern term. Trying to trace down the precise history of different types of gyroplanes is also very confusing, and I decided to give a quick mention of most types and focus on a few of the more representative or interesting machines. Most of the data on the more obscure gyroplanes is so sketchy as to be completely untrustworthy.

* Sources include:

  • THE COMPLETE ENCYCLOPEDIA OF WORLD AIRCRAFT, edited by Paul Eden & Soph Moeng, Barnes & Noble, 2002.
  • "Hawk 4T Breathes New Life Into Gyroplanes" by William B. Scott, AVIATION WEEK, 6 November 2000, 54:56.

This document owes a good deal to a portion of "From Autogyro To Gyroplane: 1923:2003" by Dr. Bruce Charnov, which was reprinted on the Groen brothers website, a useful source of details on GBA projects.

* Revision history:

   v1.0.0 / 01 dec 06 / gvg
   v1.0.1 / 01 dec 08 / gvg / Minor cosmetic update.

 

Bensen B-8M Gyrocopter

The Bensen B-8M Gyro-Copter hangs in the National Air and Space Museum in Washington, D.C.

In 1953, Dr. Igor Bensen, an immigrant from the Russian Revolution where he had been chief research engineer of the Kaman Aircraft Corporation, established the Bensen Aircraft Corporation in Raleigh, North Carolina. He initially planned to produce commercial helicopters, but switched to the private market when he realized that the relative safety of rotary craft would be attractive to private pilots.

His first aircraft was the Bensen B-8 Gyro-Glider, which was unpowered and could be flown without a pilot license in the United States. It could be built at home from a kit that an aspiring pilot would purchase from the company or could be purchased already assembled.

His Bensen Gyro-Copter was also designed for home construction. It was first flown on December 6, 1955. The autogyro was a powered version of the Gyro-Glider and could fit in anyone's garage. The Model B-8M could also be converted from an aircraft to an automobile by simply locking its blades in place.

The most famous Gyro-Copter was the Spirit of Kitty Hawk. It received that name because it exactly duplicated the Wright brothers' first flight on its sixtieth anniversary. The aircraft also set twelve world and national autogyro speed, distance, and altitude records in May 1967 and June 1968. The aircraft held more records than any other nonmilitary rotary aircraft in the world.

Production of the Gyrocopter continued until 1987.

 

Gyrocopter - Definition

 

An autogyro (only an autogiro when made by Cierva (see below)), sometimes called a gyroplane or Gyrocopter�, is an aircraft with an unpowered rotary wing, or rotor, that resembles a helicopter. It is powered by either an engine-powered propeller or a tow cable. The movement of air past the rotor causes the lift.

The Rehler Gyrocopter (autogyro)

General characteristics

Autogyros can take off and land in short fields compared to conventional fixed-wing aircraft. They can even land straight down in some cases. When they have a jump start feature, they can jump vertically and then start flying forward so avoiding a take off run (but this does not give them a hovering ability); but this feature adds weight, complexity and expense so it is not common. If they have a variable-pitch rotor, they can flare to a soft vertical landing, using excess momentum in the rotor to perform a soft landing; this is related to the way the jump start feature is implemented.

Autogyros are notably safe. If the engine should fail, the autogyro does not stall or spin. Instead, it begins to settle like a parachute. The pilot can usually maintain some directional control by slipping the rotor.

Autogyros are neither efficient nor fast. Fixed-wing aircraft use less fuel over the same distance, helicopters usually use more.

They are typically more maneuverable than fixed-wing aircraft, but cannot hover as a true helicopter can. When helicopters became practical, autogyros were neglected for nearly thirty years. Yet they were used extensively by major newspapers to move information from city roof top to roof top.

As the infrastructure for service, repair, training and building increases the number of gyrocopter users may increase. NASA is said to be exploring the use of these sporty flying machines to encourage personal air transportation for everyone.

There are three main types of autogyro: Early examples were tractor-type, meaning the engine and propeller were in the front of the aircraft, and pulled the plane forward. Such planes usually had small wings to provide better stability. Most autogyros today are pusher-type, meaning the engine and prop are mounted behind the pilot/passengers and push the plane forward. Latterly the Little Wing LW-5 (see [1] (http://www.littlewingautogyro.com/)) in the hands of Andy Keech (see [2] (http://records.fai.org/pilot.asp?from=rotorcraft&id=4246)) has taken numerous world records as well as exhibiting exemplary stability in flight.

The final type of autogyro has Vertical Take-Off or VTO capability. Aircraft(such as the Groen) with this feature have a rotor with adjustable blade pitch (like a helicopter's cyclic) and have the ability to use the engine to spin the rotor while on the ground. The rotor blades are turned flat so they produce no lift, and the engine is used to spin the rotor as fast as possible. When ready for takeoff, the engine is decoupled from the rotor and the blade pitch is set for maximum lift. The kinetic energy stored in the rotor lifts the plane a few feet off the ground, and the conventional propeller is used to give the plane horizontal airspeed before the (now unpowered) rotor speed decays too much to keep the gyroplane in the air.

History

Juan de la Cierva, a Spanish aeronaut, invented the first successful autogiro in 1923. His craft used a tractor-mounted forward propeller and engine, a rotor mounted on a mast, and a vertical stabilizer. His first three designs the C.1, C.2, and C.3, constructed by Parnall were unstable. His fourth design, the C.4, was successful.

The C-11 and some of his later designs had a power-coupling to the rotor, the so-called "jump" feature. The rotor would be sped up before the take-off roll. The coupling would be disengaged during the take-off as the airflow began to power the rotor. This allowed the craft to take off with almost no roll at all.

The C-19 was licensed to a number of manufacturers, including Harold Pitcairn in the U.S. (in 1928) and Focke-Achgelis of Germany. In 1931 Amelia Earhart flew a Pitcairn PCA-2 to a then world altitude record of 18,415 feet.

In World War II, Germany pioneered very small gyrogliders towed by submarines to provide aerial surveillance. It's reported that German gyro pilots were often forgotten in the heat of battle when the submarine dived suddenly. The Japanese also developed the Kayaba Ka-1 Autogyro for reconnaissance, artillery-spotting, and anti-submarine uses.

The autogyro was resurrected when Dr. Igor Bensen saw a captured German U-Boat's gyroglider, and was fascinated by its characteristics. At work he was tasked with the analysis of the British "Rotachute" gyro glider designed by expatriate Austrian Raoul Hafner. This led him to adapt the design for his own purposes and eventually market the B-7.

Post WW2 autogyros, such as the Bensen B-8M gyrocopter, generally use a pusher configuration for simplicity and to increase visibility for the pilot. For greater simplicity, they generally lack both variable-pitch rotors and powered rotors.

Since Bensen, a number of improved designs have been constructed. Two FAA-certified designs have been commercial failures, despite performing well.

Modern autogyros are quite frisky on the ground, and versions with brakes and tied rotors have been driven successfully in heavy automobile traffic.

Bensen's design

The Bensen Gyrocopter�, the protoype of many post WW2 gyroplanes, actually consists of three versions, the G-6, G-7 and G-8. All three were designed in both unpowered and powered forms.

The basic design is a simple frame of square aluminum or galvanized steel tubing, reinforced with triangles of lighter tubing. It is arranged so that the stress falls on the tubes, or special fittings, not the bolts. All welds or soldered structural joints should be inspected.

The rotor is on the top of the vertical mast. The outlying fixed wheels are mounted on an axle (of tubing). The front-to-back keel (more tubing) mounts the forward wheel (which casters), seat, other tubes, engine and a vertical stabilizer. Some versions mount seaplane-style floats and successfully land and take off from water.

It is common for the vertical stabilizer to drag on the ground unless it is cut away. This is also why many frames have a small wheel mounted on the back end of the keel.

The rotor is not symmetric as in some helicopters. It has a true wing shape. Most light gyroplane rotors are made from aluminum, though aircraft-quality birch was specified in early Bensen designs, and wood/steel composite is still used in the world speed record holding Wallis.

Flight Controls

There are only three flight controls: a control stick, rudder pedals and a throttle.

The Bensen pattern control stick drops down from a hinge that mounts the main rotor's bearing atop the vertical tube. The hinge lets the rotor tilt forward or backward. The hinge prevents the rotor from hitting the ground.

Since the rotor precesses like a gyroscope, exerting forward or rearward force causes the vehicle to roll left or right.

Later designs often substitute a more-complex between-legs control stick.

Another control is a simple set of rudder pedals that move the hinged back half of the vertical stabilizer. This lets the pilot keep the craft lined up in the desired direction of motion. The stabilizer is mounted behind the pusher propeller, so one can steer the craft on the ground and during takeoff. Some builders use a pushrod between the rudder bar and stabilizer. Others use cables.

Some simple autogyros, including Bensen's G-6, do not use controllable-vertical stabilizers at all. They are fixed - this works for towed gyro gliders, but not for powered gyros.

The throttle and choke are usually levers mounted where convenient- often under the seat.

Flight characteristics

Autogyros are often regarded by fixed-wing aircraft pilots as "dangerously unstable", which is certainly true if one tries to fly a autogyro using fixed-wing principles. Piloted properly, a autogyro is slightly safer than a fixed-wing aircraft because it cannot stall. A "stall" does not mean an engine-out event, it means a fixed wing aircraft is travelling too slowly for the wings to produce lift. Since the rotor of a autogyro is always spinning, it cannot stall. If forward airspeed becomes zero, the autogyro will slowly drift to the ground, rotor still spinning. A vertical landing in this manner will not critically damage most autogyros.

One weakness in certain types of autogyro is pitch instability (pitch is the tilting up or down of the craft as viewed from the front or the back). Pitch instability can be a problem because autogyros lose rotor control authority in negative-gee forces (positive-gee forces push people into their seats; negative-gee forces make people float out of them, such as driving over a hump back bridge at high speed in an automobile). Negative-gee forces "unload the rotor" and rotor control authority is lost. A flying autogyro hangs from the rotor much like an object hung from a string. As long as the plane is hanging from the rotor, stability is maintained. The instant zero or negative-gees are introduced, rotor speed begins to decay and the forces stabilizing the plane are lost.

Negative-gees can be caused by Pilot-Induced Oscillation, or PIO. PIO happens when a pilot adjusts his pitch too much too quickly, then makes a countering control input to bring the pitch back. The countering input often overcompensates, and the autogyro begins to buck like a bronco. You can see a similar effect when some learner-drivers are doing kangaroo-hops in a car with a stick shift and clutch. This is most likely at higher engine throttle settings. If the pilot continues to fight the plane, the rotor (which is flexible) can slow down due to the lack of positive G force, and can flop down and strike the spinning propeller, which destroys both and sends the autogyro into an uncontrolled fall. The way to avoid this during an incipient PIO is to apply gentle back pressure on the stick (to raise the nose in pitch) and cut engine power. Note that this is the exact opposite of what fixed-wing pilots are trained to do when in trouble, which has lead to some unfortunate accidents and the autogyro's undeserved reputation for being "dangerous".

Another danger is "bunting over" or a Power Push-Over (PPO). An autogyro's vertical airspeed (climb or sink rate) is directly coupled to airspeed. Increase forward airspeed, increase rate of climb. In order to maintain level flight at high engine throttle settings, the pilot must tilt the rotor forward to prevent climbing and maintain level flight. The rotor thus becomes more nearly horizontal, and the control stick becomes more sensitive.

Too much forward stick, and the autogyro's rotor can aim down towards the ground. When this happens, negative-gees occur, rotor speed drops too low to provide lift, and a high-thrustline autogyro is then pitched forward by the propeller thrust and tumbles end-over-end in a somersault. It is impossible to regain control after a full PPO.

Two factors can lead to pitch instability: no or too small horizontal stabilizers (h-stabs) on too short a tail and high thrustline propeller placement which destabilises the force diagram. A large h-stab, ideally in the prop wash (where the propeller blows on it) will reduce the tendency of an autogyro to bunt over as a result of improper control input by damping the control response.

If the propeller thrustline in an autogyro is high -- meaning the axis of propeller power is above the center of gravity for the aircraft -- the autogyro tends to pitch forward under sudden power application (see PPOs above, as for why this is Bad). (Unfortunately, Bensen-type autogyros have a notably high thrustline.) If the thrustline is low, the autogyro tends to pitch up under sudden power application, which is harmless. It's difficult to have a low thrustline without a really tall autogyro (such as a "Dominator" style) however, so most autogyro designs simply try to get the thrustline as low as possible though still being slightly above the center of gravity.

In spite of these dangers, most autogyros are designed to reduce them. Also, the majority of autogyro pilot training involves avoidance of PIO and PPOs.

Autogyro rotors usually feature a teeter-hinge in the middle. Picture a autogyro or helicopter from above, rotor spinning clockwise. If the aircraft is flying forward, the rotor tips on the left are traveling faster than the aircraft, while those on the right are actually going backwards relative to the craft. If the rotor blades were fixed, this would produce uneven lift -- more lift on the left side, since those blades are traveling faster. The teeter hinge on each blade lets it "flap" up and down. As the blade swings on the left, the increased speed makes it flap up with a greater angle of attack to the relative wind. This increases drag and reduces lift. As it swings to the right, it's now going slower, relative to forward speed. This reduced drag lets it flap down and get a better bite into the air, increasing lift.

Pitch is controlled by a conventional joystick coupled to the rotor. Pulling back on the stick tilts the rotor back, increasing lift and decreasing forward airspeed. Pushing forward on the stick decreases lift and increases airspeed, as long as it is not pushed much beyond horizontal (see PPO above). The planes direction is controlled by rudder pedals.

Records and Application

As of 2002, Wing Commander Ken Wallis, an enthusiast who has built several gyroplanes, holds or has held most of the type's record performances. These include the speed record of 111.7mph (186km/h), and the straight-line distance record of 543.27 miles (905km). The record picture is continually changing, and on 16/11/2002 Ken Wallis increased the speed record to 207.7 km/h - and simultaneously set another world record as the oldest pilot to set a world record! See: [3] (http://records.fai.org/pilot.asp?from=rotorcraft&id=335)

Ken Wallis also built and flew one of the most famous autogyros - "Little Nellie" - in the James Bond movie "You Only Live Twice".

Gyrocopters are often used to herd range animals. A gyrocopter 'cowboy' holds the worlds record for total hours in the air each week.

The Bensen design has also been used by hobbyists, sight-seers and scientists (for game counting).

Kits

Many autogyros are assembled from kits.

Kits with all parts, ready to assemble, are listed for US$19,550 as of 7/18/2002. This is extremely inexpensive for an aircraft. This includes an engine, the major expense. It can be reduced. Some people are clever at scrounging materials. However, scrounging increases one's construction time and program risk. Buying both the engine and rotor hub is recommended by most vendors.

Some people who actually completed an autogyro have said that it took them about a year, working in their spare time. Careful estimates place most build times at 100 to 200 hours.

Kit vendors often say that since it has relatively few parts, hobbyists can assemble it more rapidly and correctly than most fixed-wing kit aircraft. Kit vendors recommend working on it every day for an hour or two.

Warnings

Most vendors recommend that a new pilot have at least ten hours of instruction by a rated instructor in small fixed-wing aircraft, followed by at least two hours of instruction in a dual-place autogyro with an experienced instructor. An autogyro is more similar to a fixed-wing aircraft than to a helicopter. One must be able to land safely and reliably before attempting to fly any aircraft alone.

Autogyros are relatively safe, but not foolproof. There were 19 fatal autogyro accidents reported to the FAA between 1996 and 2001. Autogyros are aircraft. Do not neglect safety precautions: training, instrumentation, flight rules, preflight checklists and periodic inspections and maintenance. In the United States private and commercial pilot licenses with rotorcraft category and gyrocopter class rating are issued, or the rating is added to an existing license for other aircraft. Requirements include completing required training times, passing written exams, and successfully doing oral and practical tests. A "single place only" endorsement is issued if the in-flight test is done in a one seat aircraft.

"Learning to fly the rotor" is a vital ingredient for safe flight in an autogyro - models and rotary kites can help the learning process, and towed gyro-gliders and boom-trainers are ideal tools for this as well as being cheap to build and fly.

See also

 

 

 

 



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