An autogyro, or autogiro, 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 (autogiro).
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2 History 3 Bensen's design 4 Flight Controls 5 Records and Application 6 Kits 7 Warnings |
Autogyros can take off and land in short fields compared to conventional fixed-wing aircraft. They can even land straight down. 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.
They are 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.
Juan de la Cierva, a Spanish aeronaut, invented the autogyro sometime around 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-Angelis 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 autogyro was resurrected when Dr. Igor Bensen saw a captured German U-Boat's gyroglider, and was fascinated by its characteristics.
Modern autogyros, such as the Bensen B-8M gyrocopter, generally use a pusher configuration to increase visibility for the pilot. For simplicity, they 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.
The Bensen Gyrocopter (TM), the protoype of modern 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 a helicopter. It has a true wing shape. Most light gyroplane rotors are made from aluminum, though aircraft-quality birch was specified in early Bensen designs.
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 modern autogyros, including bensen's G-6, do not use controllable-vertical stabilizers at all. They are fixed.
The throttle and choke are usually levers mounted where convenient- often under the seat.
As of 2002, Wing Commander Ken Wallis, an enthusiast who has built several gyroplanes, holds 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).
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).
Many autogyros are assembled from kits.
Kits with all parts, ready to assemble, 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.General characteristics
History
Bensen's design
Flight Controls
There are only three flight controls: a control stick, rudder pedals and a throttle. Records and Application
Kits
