COMMENTS BY RALPH AND DON
What follows is a series of comments on various aspects of flight handling and stability as demonstrated by the prototype Gyrobee.
RESPONSE TO THROTTLE CHANGES
The Gyrobee is almost pitch-neutral with respect to throttle changes. In the case of small changes in throttle, there is essentially no observable change in pitch. In the case of major changes in the throttle setting, it will pitch up modestly with an increase in power and pitch down in a similar fashion with a reduction in power. The result is a high degree of self-regulation with respect to airspeed. With more power the machine doesn't really speed up significantly, it just climbs at a faster rate. Similarly, when reducing power, the machine maintains essentially the same trim speed but descends.
PITCH ATTITUDE IN FLIGHT
Some gyros fly with a distinctly nose-down attitude as airspeed increases. The "wheelbarrow" attitude gives you the uncomfortable feeling that you are standing on the rudder pedals. Assuming it is properly trimmed, the Gyrobee will fly with a slight positive attitude at all speeds within the flight envelope. This photo is an air-to-air shot of the Gyrobee from a hot-air balloon. At this point I was cruising past the balloon at somewhere between 40 and 45 mph.
The only exception to the slight nose-up attitude is when you are in a very steep, low-throttle descent. In this case the nose will come down a bit, usually resulting in a near-level attitude (see the final approach shot to the left), but the attitude is very constrained and quite comfortable.
PITCH DYNAMICS IN ROUGH AIR
On entering a thermal, the pitch response varies from no change (modest lift) to a very moderate pitch-up response. Almost immediately the aircraft will return to its original pitch attitude. The nose-up response is not divergent and requires no control input from the pilot for correction! That, despite the revisionist views of our current crop of "experts" is a stable response!
Thermal exit is the reverse of the entry response. In the case of a strong thermal, the nose will pitch down slightly on exit, followed by immediate recovery to the starting pitch attitude.
Response to gusts is similarly benign. Now I am quite aware that some of our "experts" feel that only constant control inputs keep low-profile gyros on an even keel. I can't speak for other designs, but in the case of the Gyrobee such assertions just are not so. During our early experience, we had been so brainwashed about the onset of PIO that we simply used the stick as a trim control in pitch and NEVER used it to counter pitch digressions. If the nose bumped up or down as a result of thermals or gusts, the stick was not used to make corrections, for the gyro itself would correct within moments. Even today, when doing long cross-country flights, both Don and I essentially "lock up" the stick in pitch by resting our right hand and arm on our right thigh. The Gyrobee simply flies steadily on, mile after mile, with no differential pitch control inputs.
PIO AND PPO
For the past eleven seasons we have flown the Gyrobee in all kinds of conditions, including thermals, storm fronts, winds over 30 mph, and at least two occasions where visual contact was lost with both the horizon and the surface. On both Rotordyne and Brock blades it has been a real pussycat. Geoff Taber (in the Gyrobee) and Jim Fields (in the Honey Bee) report similar handling with Rotor Hawk blades. In short, handling is solid and inspires confidence. This evaluation might be a delusion inspired by dumb luck if we only had a few flights logged, but we are talking about hundreds of flights and eleven seasons of experience! We are also talking about an aircraft where we taught ourselves to fly in less than a month after flying a weight-shift Quicksilver fixed-wing - probably the most easily-flown aircraft even created. Within another month we were flying cross-country flights of up to 20 miles at altitudes of 1000 to 1500 feet. If the Gyrobee were not as solid and predictable as I have suggested, what are the chances we would have survived the experience?
CONCLUSION
I will be adding "testimonial" accounts from other pilots as they become available, but it is obvious that we are quite pleased with the flight characteristics of the Gyrobee. The bottom line is simple! There are many reasons why you might choose to build or not to build a Gyrobee, but stability and handling issues need not be high on your list.