I sure like my gyro, but if I could start all over again, I think I would change this and this and perhaps that. Sound familiar? It’s the curse of the real gyro nut. This malady struck me again about three years ago after having flown my Hollmann two-place gyro for about three and a half years.
We were all pleased with its performance but I wanted to add some creature comforts, wider seats and larger instrument panel. The problem with changing one thing is, it leads to other changes and finally you end up building a completely new ship from scratch.
After resigning myself to that fact, I set out to put a lot of ideas that I have been toying with into more practical form. An airframe I have always admired for its sleek looks, side-by-side seating, and light weight is the McCulloch J-2.
However, its general performance leaves something to be desired in comparison to, for instance, the Air and Space 18A. Both have 180 HP power plants, but the 18A has a much larger rotor system and excellent performance. On the down side, tandem seating which puts a large side area forward of the mast, creating yaw problems.
Also, the 18A is about 400 pounds heavier than the J-2. My first design criteria, therefore, would be to create a craft with J-2 looks, side-by-side seating with plenty of room, and 180 HP. My empty weight goal will be under 750 lbs.
For comparison, the J-2 weighs 1,000 lbs. empty and the 18A 1400 lbs. empty. Attached to the airframe a 30-foot diameter rotor will give good performance. Since my criteria calls for a 180 HP power plant, a prop diameter of six feet would be the minimum. Any smaller would not be able to use that much horsepower in an efficient manner.
Since this is a much larger prop than the Hollmann airframe is designed for, a new airframe must be created that gives not only airframe clearance but adequate ground and rotor clearance. Egad, with all those clearances the new design is 10″ higher and will not fit through the shop doors! This problem is solved through the use of a split mast.
The mast upper section can be separated from the lower section. It is reinforced in such a way that it is stronger than a one-piece mast. The reinforcement also transfers the tremendous mast bending loads present in my machine to other airframe areas generating a wholly stronger craft.
Other basic airframe changes incorporate independent hydraulic main wheel brakes, castoring nosewheel, and a longer, wider cabin for us long and wide types. The cabin sports a full VFR panel with engine/rotor tach, 360 channel comm./VOR nav radio. Pilot and passenger have an intercom which is controlled by a push-to-talk switch on the control stick.
A heavy duty prerotator designed around a gear and shaft system supplies enough oomph to kick the rotor up to about 150 RPM (about 40% of flight RPM). With a large rotor system you quickly learn to appreciate the benefits of an adequate prerotator. It can be a bear-to handle a large rotor at low RPM on a windy day.
It took me three years to finish the ship. You might think that is a long time, but remember I started with a blank sheet of paper and a bunch of half-formulated ideas. For instance, fiberglass molds had to be made from scratch some two or three times when the original idea didn’t work out.
Many a week went by with no work completed while a sticky problem was resolved. I am so grateful for the support of so many loyal friends who put up with my being a real pain-in-the-butt, pestering for ideas or just another set of cooperative hands.
I wished I was Chuck Yeager when the day came to test-fly my creation — then maybe the butterflies in my stomach would let me alone. Keep in mind that I don’t know of another gyro that weights as little (760 lbs. empty) as mine with as much brute horsepower. How this bird will react is something I have no basis of comparison for. Well, upward and onward.
I was correct in assuming this bird was different. On the initial test flights its potential displayed itself. The first flight was at greatly reduced power after many low- and high-speed taxi runs.
Ground steering is very quick and you learn to keep your feet off the brakes once the rudders become effective. The one major difference from my old Hollmann ship in takeoff is the torque generated by that 180 HP swinging a large prop. It tends to roll the ship to the right when it breaks ground.
To counter that, I must have at least 50 MPH on the clock so the rudders are at maximum efficiency. One is reminded of the World War II fighters that had to start their takeoff roll at less than full power so enough speed could be achieved for rudder effectiveness to counter engine torque.
With me (230 lbs.) and full fuel, a spectacular takeoff can be achieved using only 2300 RPM (Lycoming redlines this engine at 2700 RPM). 2300 RPM gives about 1000/FPM of climb. 2700 RPM gives 1450+/FPM and takes your breath away. At full power I can easily climb out of the traffic pattern before crossing the end of the runway. Cruise seems to be about 70-73 MPH at 2000 RPM.
With only 30 hours on the ship, I’ve not attempted higher speeds than 95 MPH. A 170 lb. passenger has a surprisingly minimal effect on performance, but I suspect that has more to do with a large power reserve that goes unused when flying solo.
The ship has flown at 1270 lbs. gross weight (that’s 515 lbs. of useful load) with no CG problems and 600+/FPM climb. Like anything else, a couple of post-test flight changes were made. Cooling a big Lycoming pusher can be a problem.
It requires a large volume of fast-moving air. The original location of the air intake proved to be wrong and too small. After cylinder head temperatures indicated a problem, we taped some wool yarn to the old intake.
Flying with the yarn quickly showed the source of the problem — air was passing over the intake rather than into it. Several alternative configurations were suggested, but which would be best? To test a possible alternative would mean creating a flight-worthy example.
I didn’t want to waste weeks on a less than optimal solution. What was needed was a full scale wind tunnel capable of housing the airframe and generating 60-70 MPH winds, which could be used to test cooling intake mockups.
Since a wind tunnel is a little hard to come by, towing the ship on its trailer without the rotors at 60 MPH should produce the same effect. Several wood and cardboard mockups were tried and the best was copied into fiberglass for permanent use. The trailer wind tunnel saved a great deal of time.
I’m sure, though, that a lot of people on the local interstate wondered what that, crazy man is doing hanging out the back of that car watching that contraption on the trailer. It became evident that some type alternator was needed to keep the battery topped off.
The electric starter and radio quickly depleted the battery. The stock alternator weighs 20 lbs. and produces 30 amps. — very unsatisfactory. A new one was made using available parts, another four weeks invested in that side project.
The result was a unit weighing 4½ lbs. and giving 12 amps. All in all, I am very happy with my new craft. It is a truly unique machine with heart-stopping performance. I have been asked if 180 HP is too much for this type of gyro.
My answer being that 180 HP is not the ideal engine — 150 HP is — unless you set out from the beginning to build a machine whose primary purpose is performance. For the low-time gyro pilot — absolutely, unequivocally not. 180 HP in a light ship can be a handful. To all my gyro friends, good luck and good flying. Skip Tyler, Glen Cove, NY 11542.
Find more information on the Shadow Gyrocopter at Vortech.
GYROCOPTER SAFETY NOTES: THE POWER LINE MENACE
The unseen power line is the cause of many rotorcratt accidents. And most wire strikes prove fatal to the pilot. This fact was just brought home to all of us loud and clear after the tragedy in California this June of Russ Jansen, a well-known, long-time gyro enthusiast from Ridott, Illinois.
We have determined, “He simply did not see the wires.” A lot of private strips have wires across the end. In our normal flying we often fly lower than we should in unfamiliar territory.
We pilots must look for POLES. Wires are hard to see, and in a lot of positions and conditions, cannot be seen. So, we look for poles. Poles spell DANGER. The wires from poles are killers! Let’s all watch for poles and then we know there are wires that can mess up our day, and our whole life!
LEARNING TO FLY THE GYROGLIDER
NOTE: All these lessons are meant to be used in conjunction with an experienced gyro pilot as your instructor. Learning on your own may be a hazardous experience.
Your instructions in learning to fly a gyroglider are divided into 4 lessons. Your instructor will teach you one lesson at a time until he believes that you are proficient enough to proceed to the next one. You will proceed with the lessons at your own pace.
You can even complete one or more lessons in one day if your instructor feels you are up to it. It is not unusual to solo in one day; neither is it unusual to take much longer. You will not be pushed beyond your abilities.
GYRO FLIGHT LESSON: GETTING INTO THE AIR
On a dual seat gyroglider your instructor will first demonstrate the following lessons to you. Then he will allow you to lightly hold the stick and follow his movements as he does the maneuvers again.
He will then allow you to be the sole controller of the gyro while he will be there only for emergencies. Only when he is fully satisfied that you are competent to fly the gyro will he allow you to solo.
As the gyro and rotors begin to pick up speed, the lift that the rotors are producing increases. At approximately 20 mph and 300f rpm (rotors tilted full back) the gyro’s nose wheel will come off the ground and it will rock back on its tail wheel. This is a clear indication that the gyro is almost ready to fly.
There are two ways to take off from this point: (a) Keep the stick fully back and take off with the tail wheel touching last, or (b) lower the nose so that the nose wheel almost touches the ground and take off nearly level.
Method (a) will get you off the ground faster but tends to wear out the tail wheel and makes it more difficult to get the gyro level after take-off.
Method (b) results in a longer run and higher airspeed take-off, but is smoother and more controlable. This method is preferable because it is the proper way to take off in a gyrocopter and you should develop good habits as soon as possible.
With the nose wheel only off the ground, the instructor will demonstrate how to make the gyro balance on the main wheels, not touching the nose wheel or tail wheel, and let you practice this maneuver.
This helps you get a feel for the stick movements required to hold the gyro at one particular attitude, and teaches you how to keep the nose wheel just skimming the ground for a proper take-off.
Once you’ve accomplished this balancing, the tow vehicle will increase in speed and the instructor will demonstrate the take-off and flying straight and level. You will be at an altitude of approximately 5 ft., directly behind the car.
FLYING STRAIGHT AND LEVEL
As the instructor lets you practice taking off and flying straight and level, you will begin to notice some of the gyro’s handling characteristics. It is best to fly using only one hand (two hands are alright to steady the stick while on the ground, but switch to one hand when the nose wheel comes off) and a light grip because of the gyro’s sensitive controls.
A two-fisted or “death grip” on the stick can cause you to over control. You will learn how to maintain altitude by moving the stick forward or backward and staying centered behind the tow vehicle by moving the stick right or left.
The control is so sensitive that you can maintain altitude and stay directly behind the tow vehicle while not moving the stick more than 1/4 inch in any direction. Don’t let this scare you, for you will soon get used to it.
LANDING THE GYROCOPTER
Every time that the gyro takes off it is going to land, one way or another. The proper method is to bring the gyro down by easing the stick forward, until the wheels are about 1 or 2 feet off the ground.
As the tow vehicle slows down, try to hold the gyro off the ground by gently easing back on the stick, maintaining that 1-2 foot altitude. Soon you will have the stick all the way back and, as the tow vehicle continues to slow down, the gyro will settle gently to the ground.
You must be directly behind the tow vehicle at touchdown or the gyro could roll over. Once on the ground, keep the rotor tilted back (stick back) to keep the tow line tight. The tilted-back rotor acts like a brake and helps slow down the gyrocopter.
For the turn at the end of the runway, make sure the gyro has slowed as much as possible, then push the stick all the way forward so that the nose wheel has enough weight on it for good turning and braking. When the gyro is headed down the runway again, pull the stick back to get the blades spun up for another take-off.