This is not your father's gyroplane
This is Not Your Father's Gyroplane
By Timothy OConnor, CFI
Rotorcraft were born on January 9, 1923, when Juan de la Ciervas autogyro first took to the air. All helicopters, gyroplanes, Gyrocopters, and gyrodynes owe their existence to this first autogyro and Juan de la Ciervas patented technologies. Autogyros flourished for the next several decades, enjoying great advances in technology. The autogyros of this time still hold a better safety record than any other type of production aircraft. However, Juan de la Cierva was ironically killed as a passenger in a commercial airline airplane accident.
His death is ironic because Cierva got the idea to develop the autogyro when pondering how to make airplanes safer. It left the autogyro industry ill prepared to weather the Great Depression or see significant service in the Second World War. Consequently, the commercial production autogyros didnt survive. Through Ciervas rotorcraft patents, the helicopter did survive, and as youre no doubt aware, it has become a strong and critical branch of aviation.
The autogyro was reborn in the 1960s from the hands of Dr. Igor Bensen when he used knowledge from his research of World War II autogyro technology to create and sell plans for a homebuilt autogyro. Bensens autogyro was configured as a pusher prop design which has advantages in small autogyros.
Bensen called his make of autogyros Gyrocopters and copyrighted the name for his line of aircraft. The small and inexpensive design became wildly popular, and by selling them through advertisements in Popular Mechanics magazines, hecreated what we know today as the homebuilt aircraft market.
The Bensen Gyrocopter was so well marketed and so successful that even today many people erroneously call gyroplanes and autogyros Gyrocopters, even though Bensen Aircraft Company has been out of business for many decades and few Gyrocopters are still flying. The FAA uses the term gyroplane to describe all aircraft that fly in auto-rotating flight. Purists prefer to use the term autogyro (sometimes spelled autogiro) because that was the name given to these aircraft by the inventor Juan de la Cierva. If you would like to know more about the amazing history of autogyros and the rebirth of autorotation flight, get the book From Autogiro to Gyroplane by the leading rotorcraft historian, Dr. Bruce Charnov.
Just as autogyro technology was again about to become part of mainstream aviation, it was again stunted by an ironic twist of fate. Riding the coattails of Bensens success, a number of new startup companies began producing gyroplane kits for the homebuilder market. These machines offered stylish designs, and some had two-place seating that could be used for training and sharing the unique gyroplane experience with a passenger. These companies, however, didnt produce their designs with the aid of aeronautical engineers. The new kit companies took Bensens design and bolted larger props, engines, pods, and other accessories onto these aircraft with no consideration of what effect this would have to the center of gravity and propeller thrust alignment or pitch stability.
The result was a large number of kit gyroplanes introduced into the market that had a critical flaw in their design. This critical flaw was that when these aircraft reached a certain level of pitch instability during flight they would execute a power pushover (PPO). A PPO is a fatal unrecoverable action by the gyroplane that only occurs in flawed gyro designs. The original autogyro design patents used a thrust line to center of gravity alignment, which made PPOs impossible.
This flaw cost the lives of many gyro pilots and gave the gyroplane a reputation of being a widow-maker. Its especially ironic given that from an engineering perspective a properly designed gyroplane is one of the safest, if not the safest, aircraft design you can fly, and the early autogyros have an unmatched safety record.
The manufacturers and the hobby in general took a long time to realize the existence of this flaw. You would think that you could tell an aircraft was pitch unstable by simply having an experienced pilot take it for a spin around the pattern. While this is mostly true for fixed-wing aircraft, it isnt true for gyroplanes.
Nearly all small gyroplanes use an offset gimbal rotorhead. This part has a pitch stability masking effect that hides severe and dangerous pitch instability from even the most experienced gyroplane pilots. A seriously pitch unstable gyroplane will appear to the high-time gyro pilot as a benign well-mannered flyer until the pilot exceeds the masking threshold of the rotorhead. Once the pitch masking ability of the offset gimbal is exceeded, the pilot has only moments or even seconds to correct the situation before entering the unrecoverable PPO.
The majority of the homebuilt gyroplane community is now aware of the flaw introduced into older kit designs. Virtually all new kits sold in the United States today are stable, PPO-resistant or PPO-proof designs. Unfortunately, used gyroplanes that are pitch unstable can still be found for sale in the United States, or even new in other countries. With a little research, you can find high-time gyro pilots showing hands-off flying in a dangerously flawed gyroplane design. These pilots are erroneously thinking theyre displaying the qualities of a stable gyroplane when theyre actually showing the action of their offset gimbal rotorhead design. I assume these pilots have let owner pride keep them from understanding the flaws that affect these machines, or they simply havent taken the time to update their knowledge of the sport.
The most important new development in autogyro aviation is the realization by the gyroplane community that pitch stability is critical in gyroplane design. Current designs are pitch stable and offer outstanding flight envelope safety and ease of flight.
Some gyroplane designers have made their aircraft PPO proof by returning to Ciervas center line thrust (CLT) design while others have taken a new approach by designing dynamic pitch stability into the airframe. Both design approaches have advantages and disadvantages, but more importantly they produce safe machines that are easy to learn to fly and are for all practical purposes PPO proof.
With the gyroplane community well on the mend from the PPO plague, new technologies and the promise of production-certified gyroplanes are once again developing. This article doesnt have the space for a full tour of all of the sleek, safe new gyroplane models now appearing on the market. Dont despair; you can find photos of some of the newest models on the Popular Rotorcraft Association (PRA) webpage and free EZine (www.PRA.org). In particular, youll want to look up the new machines from Genesis, Magni USA, Rotor Flight Dynamics, Xenon, and others.
Our first stop in review of new gyroplane technology is at Larry Neals company, Butterfly Aircraft LLC (www.TheButterflyllc.com/). Larry Neal is one of the most extraordinary people in the world of gyroplanes. He has brought to market some of the most innovative new technologies since the time of the original autogyros. Gyroplanes designed by Larry Neal have the option of using his G-Force landing gear that allows gyros to flair as much as 50 feet above a hard surface and land vertically without risk of a bent part or a bruised pilot. This technology has to be seen to be appreciated, so take my advice and check out the amazing videos of the G-Force landing gear on the Butterfly website and YouTube.
The Butterfly company has also produced the Super Sky Cycle, a roadable gyroplane that is a street legal motorcycle and modern flying gyroplane. The Super Sky Cycle hasnt received the press of the Terrafugia flying car, but it has put on a lot more miles in the air and on the ground!
Larry Neal is also developing a Metro Launch system for his gyroplanes. Most homebuilt gyros must roll down a runway to allow their blades to spin up for takeoff. Vertical takeoffs (known as jump-takeoffs in gyroplanes) are available in vintage and expensive models but are rarely found in homebuilt machines. The Metro Launch system promises to bring near jump-takeoff performance into the homebuilt market. Watch this video demonstration.
For our next stop on the tour of new gyroplane development, were going to look at the Sportcopter II (SCII), a U.S.-made and designed gyroplane that utilizes the latest design technology and is powered by a Lycoming IO 360. SCII has evolved over the past three years since it made its debut at EAA AirVenture Oshkosh 2007. The gyroplane was recently featured on MTVs show Megadrive. If you missed the show, you can view it on the MTV website. A smaller version of SCII will be ready for the gyroplane special light-sport aircraft (S-LSA) market as soon as the FAA approves S-LSA production gyroplanes.
While many gyroplanes are open cockpit machines, the new Sportcopter II and the new Magni Orion, an Italian design, are fully enclosed modern gyros with side-by-side seating, powered by aircraft engines. Once S-LSA gyroplanes are approved by the FAA, both of these machines will be available as factory-built, ready-to-fly aircraft.
Our last stop on our mini tour is Carter Aviation. A few years ago Carter Aviation did the impossible; they broke the Mu-1 barrier. Mu-1 (μ-1) is a relation between flight speed (mph) and rotor speed (R-rpm).Breaking the Mu-1 barrier for rotorcraft is akin to breaking the sound barrier for fixed-wing aircraft. A rotorcraft that can fly past Mu-1 has the potential to fly faster and more efficiently than any other rotorcraft on the planet. Not only is the Carter technology fast and efficient, but it also has less complexity than a tilt-rotor or other vectored thrust vehicle. This technology, known as slowed rotor compound (SR/C), combines the efficiency and speed of conventional fixed-wing aircraft with the vertical takeoff/landing and slow speed flight of helicopters and gyroplanes.
Carter Aviation has been in the news the last couple weeks announcing its progress with its new Personal Air Vehicle (PAV). The PAV incorporates several significant advances developed during the testing of Carters original proof-of-concept aircraft and is likely very close to what will become the first production aircraft using the new technology. For both the groundbreaking Mu-1 flights and the recent PAV milestone flights, the test pilot has been Larry Neal. Yes, that is the very same Larry Neal, owner of Butterfly Aircraft LLC and maker of the G-Force landing gear, Super Sky Cycle, and Metro Launch system. You can learn more about the new PAV and the significance of the Mu-1 barrier at www.CarterAviationTechnologies.com.
The vast majority of gyroplanes available today can be flown with a sport pilot certificate or as an ultralight. Kits currently available in the United States are certifiableas experimental light-sport aircraft (E-LSA) or experimental. If the FAA approves the petition for S-LSA gyroplanes, factory-built gyroplanes will quickly be available from a variety of manufacturers. If you already hold a U.S. pilot certificate, getting a sport pilot category/class add-on for gyroplanes requires only a few hours of transition training and a proficiency check. No written exam or examiner checkride is necessary.
If youre a pilot or aviation fan but havent yet taken an interest in the world of gyroplanes, now is an excellent time for you to do so. Gyroplane advances are appearing in all sectors of aviation from world record flights around the globe to new ultralight kits that can tear up the sky like a flying motorbike. Gyroplanes, even very light ones, can handle strong steady winds, land easily in a crosswind, cant enter a stall or spin, are easy to build and simple to maintain, and will land with a no-roll landing even during an engine out. There has never been a better time to take the magic carpet ride only gyros can give. For a basic introduction to gyroplanes, watch this video by Dan Donley.
Tim OConnor is a fixed-wing and gyroplane pilot, flight instructor, and author of the book You Can Afford to Be a Pilot. Tim posts to the Rotary Wing Forum under the username barnstorm2 and can be contacted through his Facebook page.