ARTICLE DATE 1969: Stop for a moment and think back to when you were a child. Remember that little personal “flying machine” you used to daydream about? Remember the fantastic fantasies you used to come up with about how you would fly anywhere at all, easily and freely, controlling your flight through the air as if by magic?
Almost all of us have childhood memories of some imaginary flying device we wanted to have when we grew up, and yet with tens of thousands of us traversing the turbid airways these days it seems a bit ironic that none of us, without giving up many thousands of dollars, has been able to half satisfy that autistic longing we once had.
None of us, that is, except the ones of us who have discovered gyrocopters!
The gyrocopter is, quite literally, a personal-size flying machine that one can fly anywhere, easily and freely. It is a device that can be operated by nearly anyone, even without prior flight instruction. It costs little more than a new Volkswagen – and puts the fun back into flying.
The originator of the gyrocopter design is Igor Bensen, an engineer and former test pilot for General Electric who, in 1953, established the Bensen Aircraft Corporation on the outskirts of a small airport near Raleigh, North Carolina.
There, he designed and developed the B-6 gyroglider — little more than a mass of metal tubing fitted with wooden rotorblades, to be towed high in the air behind an earth-bound vehicle. In 1955, the improved B-7 model was developed, then the B-7M followed, a gyroglider fitted with a 40-hp pusher engine — a gyrocopter.
Igor Bensen went into business selling plans for his small copter. Today, the B-6 rests in peace at the Smithsonian Institute Air Museum of Washington. D.C. The Raleigh-Durham Airport is no longer small: it handles whisper-jets daily on two runways. And the business Bensen established years ago is now a full-time enterprise serving orders from customers all over the world.
The Bensen B-8 gyroglider of today is a single-seat, all-metal design. It may be built from raw materials for less than $500: however, for those home-builders who lack access to a drill press and are afraid of the word “screwdriver.” factory-finished component kits which bolt together quickly like an Erector Set may be had for some $700 more.
For an additional $600 or so, add an engine and you have instant gyrocopter. Depending upon how much work you want to do, a complete gyrocopter will run between $1500 and $3000. The aerodynamics of the gyrocopter are relatively easily understood.
In the gyroglider as well as the gyrocopter, the overhead main rotor is not powered. What does spin the rotorblades around is the passage of air upward through them, somewhat in the fashion of a pinwheel. The rotor disc is tilted hack a few degrees in flight to “catch” air.
Each blade has a certain fixed amount of pitch, which, in conjunction with the special airfoil, allows for the generation of lift as the rotor turns around. Naturally, the machine must have forward speed to keep the rotor turning, and for this reason hovering (except in strong winds) is an impossibility.
Likewise, a take-off roll is needed. Spinning of the rotor in the fashion described is called “autorotation”, and is the key to understanding what keeps a gyrocopter aloft. The autorotation concept is nearly as old as the Versaille Treaty, dating back to 1919 when it had been conceived of by the brilliant Spanish inventor – Juan de la Cicrva.
For three years de la Cierva dwelt upon the idea. The result was a strange craft called the “autogiro” — apparently, an airplane whose wings had been replaced by a single overhead rotor.
It may have been aviation’s ugly duckling, but it was also the first successful rotary-winged aircraft. De la Cierva also was the inventor of the lag and flapping hinges, or the “fully articulated” rotor. The autogiro was in fact, the precursor of the now prevalent helicopter, however unacknowledged this may be.
The Bensen rotor would be totally rigid were it not for a teeter hinge, which is a refinement on the flapping hinge. The Bensen rotor is so simply designed that both blades may be assembled or disassembled from the machine in less than ten minutes.
The gyroglider achieves forward motion (and hence, autorotation of the rotor) by being towed behind a car, truck, or other vehicle. In the case of the gyrocopter, the car and towline are replaced by a pusher engine; in most cases, a McCulloch engine. The 72-hp McCulloch engine used since 1957 on most gyrocopters of Bensen design was, originally, a drone engine manufactured for the military.
These engines were to be placed on dummy aircraft used for target practice purposes, and hence were by necessity low-cost and high-performance. Likewise, they were manufactured for a 35-hour life expectancy. When rebuilt, they provided the perfect power source for gyrocopters.
Today, McCulloch manufactures a 90-horsepower version exclusively for gyro use. Since the engine is a 2-stroker, the high octane aviation fuel it consumes must be pre-mixed with av-oil. But for only 83 pounds of weight, who wouldn’t mix oil with their gas?
Due to the gyroglider’s lack of engine weight, it is able to carry two people. As a matter of fact, it will carry four times its own weight. The gyrocopter, however, cannot carry more than one in its current configuration; but it grosses at 600 pounds, and will carry its own weight in very useful load.
Flying the gyrocopter is a breeze, in more ways than one. Controls consist of rudder pedals, throttle, and stick. (Overhead is standard; between-the-knees is available as an option.) Cyclic and collective pitch controls are no more.
This one is a hybrid and trade-off between airplane and helicopter, yet it flies like neither. The stick controls all attitudes of the overhead rotor, via direct linkages. It’s just that simple. Control action in flight is smooth and quick, but torque from the engine demands rudder response.
Still, there are no tricks to the machine, and it flies exactly like a flying machine should fly. It cannot stall. It will not spin. Vertical descents are possible, and stick control alone accomplishes almost any maneuver.
After a three or four hundred foot roll at sea level, the machine will break ground near thirty mph indicated. A gyro equipped with 72 horses climbs out at about 900 feet per minute maximum, while a 90-horsepower machine shoots skyward at over 1200 feet per minute.
Cruise speed can be anywhere between 45 and 70 miles per hour: the 90-hp B-8M will do just under 95 – flat out. A hot landing is anything over 20 miles per hour: ground roll on a good landing will be about ten feet. Taxi is a bit bumpy unless some air is let out of the tires, but ventilation is good.
The B-8M is advertised as having a 12,500-foot service ceiling, but the current world record is 15,800 feet, and the 90-hp McCulloch engine has been successfully run at over 20,000 feet. Range, based on six gallons of fuel, is estimated to be 100 miles: however this is easily increased by the addition of another fuel tank.
Is it safe? Fact has it that there has never been an in-flight failure of any Bensen-made component. Aside from this, the machine is as safe as you are. What about licensing? The gyrocopter falls under the category of “experimental.” meaning amateur-built.
That is to say, the aircraft in question must be 51 % assembled by the owner. Bensen helps a full 49% by manufacturing the rotor head, hub, and metal rotor blades — these items cannot be built by the homebuilder.
It must be stressed that the term “experimental” is not used to connote a presence of danger or structural question-ability, as all home-built flying machines must be licensed under this category.
And as usual, the machine is as safe as the builder wants it to be. It is interesting to note that the critical parts made by Bensen (the rotorblades for example) are designed and manufactured for a 25,000-hour total life expectancy — compare this with the life expectancy of a helicopter’s critical parts.
The gyroglider is technically a “kite” by FAA standards, and so falls outside the scope of current regulations. However, if tow-releases are to be done, or an engine put on the machine, then an ‘N’ number must be obtained. At present, this is a simple chore. Gyroglider pilots need not be licensed. Gyrocopter pilots, though, must hold at least a student certificate.
Gyroplane class licenses, student and private, are easily obtainable under current regulations: it is even possible to teach yourself how to fly a gyrocopter and receive a private pilot’s license (gyroplane class only) without paying a cent for instruction.
By law, a new machine’s first 75 hours of flight must be conducted within a 25-mile radius zone to be designated by the local FAA office. When logbooks meet this requirement, cross-country flights can become a reality.
These gyros, however, are mainly just fun machines, and virtually anyone can teach himself (or herself) to fly one. An eleven year old boy once soloed the gyroglider: many gyro pilots across the country are in their sixties. And for added fun, float versions of both the gyroglider and gyrocopter are available.
In 1963, the need for a national organization became apparent: thus, the Popular Rotorcraft Association came into existence. The PRA puts out its own magazine, is now international in scope, and has chapters nearly everywhere.
Since 1963, the PRA has exploded to a 9,000-strong membership gigantic international fly-in and, like the ripening of pumpkins, it is an annual event. Open to all comers, each year’s fly-in boasts a great many gyros, both gliders and copters, static display and operational.
Competitions are held, glider rides given, demonstrations staged, and fun is had by many. Regional meets are numerous and usually attract many gyros, not to mention spectators. A recent Northern California fly-in drew dozens of machines and a crowd of three thousand.
Chapters across the country usually hold one get-together every month. New developments are always in the works. An increasing number of gyro enthusiasts are fitting their machines with Volkswagen engines.
Some machines already sport small Lycomings and Continentals: even a number of Porsche adaptions are in the works. Pre-rotators are becoming more popular: this is where a means is devised to power the overhead rotor on the ground prior to take-off, making possible S/VTOL performance.
All three military services in this country have purchased Bensen gyro-gliders and gyrocopters. Even hobbyists behind the Iron Curtain are designing and building their first gyrocopters. Igor Bensen is hoping for FAA certification on his design in the near future.
This, of course, would provide copter customers with the opportunity to buy Bensen machines fully built, just like the “big” aircraft. Some believe all this to mark a new era in aviation. But those caught up in it only admit to the fun they’re having. And it should come as no surprise.
The gyrocopter appears to be the true embodiment of all those desiderata left out of current complicated flying machines. A lot can be said for the tiny gyrocopter. It’s fun. It’s different. And it seems to be the “little flying machine” we’ve all been waiting for.
THE HONDA Z50A MINI-TRAIL SPORT FLYING PRODUCT EVALUATION
Honda’s new mini-motorbike is a handy gadget to take along on those aerial excursions to unattended airports, your favorite fishing or hunting grounds, or your own fly-in fun spot. It can carry you (and in dire emergencies, a passenger) to civilization, or if you prefer, away from it. And it’s a ball to ride.
The Mini-Trail bike has folding handle bars and foot pegs, and the fuel tank vent can be closed and the carburetor bowl drained to make a leak-proof package that fits the baggage compartments of most large single-engine planes and light twins. At 108 pounds, the Mini-Trail is not likely to overtax those baggage compartments it fits.
Our test crew found that one man can load Honda’s mini-cycle into most aircraft, but two make the job easier. Since folding the handle bars is all that is required to “break down” the Mini-Trail, preparing it for carrying or riding takes little time.
Operating the Mini-Trail is simple. The throttle and front brake lever are located on the right handle bar, as on most motor bikes, the Honda features an “automatic” clutch, so shifting gears is a simple matter of moving the shift lever up or down with the left foot. The lever on the left handle bar, where the clutch lever normally goes, operates the rear brake.
Since it is very light, the Honda Mini-Trail will pull a “wheelie” quite easily if too much power is used when engaging or changing gears, or, as Honda puts it, “Due to the engine torque of this small vehicle, shifting gears while the throttle is open may cause the rider to lose control.” This characteristic is by no means uncontrollable, though, and judicious use of the throttle will prevent “wheelies.”
Honda also advises that the machine was not designed, equipped or approved for operations on public highways or roads. It has no lights or speedometer, and it is a bit too compact for road use. But it is a handy trail bike, and a lot of fun.